Research ArticleDistribution Microfabric and Geochemical Characteristicsof Siliceous Rocks in Central Orogenic Belt China Implicationsfor a Hydrothermal Sedimentation Model
Hongzhong Li12 Mingguo Zhai1 Lianchang Zhang1 Le Gao23
Zhijun Yang23 Yongzhang Zhou23 Junguo He23
Jin Liang23 Liuyu Zhou23 and Panagiotis Ch Voudouris4
1 Key Laboratory of Mineral Resources Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China2Guangdong Provincial Key Lab of Geological Processes and Mineral Resource Survey Guangzhou 510275 China3Department of the Earth Sciences Sun YAT-SEN University Guangzhou 510275 China4Department of Mineralogy-Petrology University of Athens Athens 15784 Greece
Correspondence should be addressed to Hongzhong Li lihongzhong01aliyuncom and Junguo He zsu iam001sinacn
Received 3 May 2014 Accepted 9 June 2014 Published 22 July 2014
Academic Editor Grzegorz Racki
Copyright copy 2014 Hongzhong Li et al This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
Marine siliceous rocks are widely distributed in the central orogenic belt (COB) of China and have a close connection to thegeological evolution and metallogenesis They display periodic distributions from Mesoproterozoic to Jurassic with positive peaksin the Mesoproterozoic CambrianmdashOrdovician and CarboniferousmdashPermian and their deposition is enhanced by the tensionalgeological settings The compressional regimes during the Jinning Caledonian Hercynian Indosinian and Yanshanian orogeniesresulted in sudden descent in their distributionThe siliceous rocks of the Bafangshan-Erlihe ore deposit include authigenic quartzsyn-depositional metal sulphides and scattered carbonatemineralsTheir SiO
2content (7108ndash9530) Ba (4245ndash5030 ppm) and
ΣREE (328ndash1975 ppm) suggest a hydrothermal sedimentation origin As evidenced by the Al(Al + Fe +Mn) ScTh (LaYb)119873 and
(LaCe)119873ratios and 120575Ce values the studied siliceous rockswere deposited in amarginal sea basin of a limited oceanWe suggest that
the Bafangshan-Erlihe area experienced high- and low-temperature stages of hydrothermal activitiesThe hydrothermal sedimentsof the former stage include metal sulphides and silica while the latter was mainly composed of silica Despite the hydrothermalsedimentation of the siliceous rocksminor terrigenous inputmagmatism and biological activity partly contributed to geochemicalfeatures deviating from the typical hydrothermal characteristics
1 Introduction
Siliceous rocks are widely distributed in the central orogenicbelt (COB) China and display a close relationship with thehydrothermal metallogenesis In the COB the distributionof siliceous rocks records the tectonic evolution of the wholeorogenic belt [1ndash4] It has been previously suggested that thesiliceous rocks were originated from hydrothermal precip-itation having a close relationship with the metallogenesisof many large hydrothermal ore deposits in China [5ndash7]especially those belonging to the SEDEX-type [8 9] Thesiliceous strata in the above hydrothermal ore deposits in
China are either ore-hosting rocks or country rocks [1 10ndash15]
The siliceous rocks of the COB and their relationshipwith the tectonic evolution andmetallogenesis are still poorlydescribed According to [16] the distribution characteristicsof siliceous rocks in the tectonic belts between two blockshave a close relationship with the tectonic evolution innerdynamic and metallogenesis [16] The relationship betweensiliceous rocks and their associated orebodies has beendiscussed by [1 4 12 17] In addition there are hydrothermalore deposits in the COB whose associated siliceous rocksare of hydrothermal genesis [1 4 17] but these ore deposits
Hindawi Publishing Corporatione Scientific World JournalVolume 2014 Article ID 780910 25 pageshttpdxdoiorg1011552014780910
2 The Scientific World Journal
Landmass
SN
SKTA
KK
CT
YZ
NQ
LowlandAral seaNeritic facies
Highland Abyssal facies
Figure 1(b)
N30∘
N60∘
(a)
Central orogenic belt
N0 300(km)
Primary tectonic sutureSecondary tectonic suture zoneAltun Tagh fault zoneBoundary of EQL and WQL
City
Wuhan
Xian
Lanzhou
Hanzhong
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC(SKC)
Figure 2
Urumqi
zone
1000 km
N34∘
E108∘ Fengtai
(b)
Figure 1 Geographical map and geological sketch of COB and the associated area ((a)mdashreconstruction map of the Middle-Permian paleo-continents [28] (b)mdashgeological framework of central orogenic belt [29 30] TA Tarim KK Karakum SN Sonnen SK Sino-Korean YZYangtze NQ Northern Qiangtang CT Cathaysian EKL Eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL WesternQinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block and DBDabie orogenic belt)
are regarded to be of orogenic type and formed during theorogeny [12] As one of the typical hydrothermal ore depositsin the COB the Bafangshan-Erlihe SEDEX deposit is a strata-bound Cu-Pb-Zn deposit with siliceous strata hosting andsurrounding ores [5] The siliceous rocks and associatedmineralisation are slightly modified during subsequent oro-genic processes [15 18 19] resulting in redistribution ofmetal sulphides in fissures as commonly observed in oro-genic type deposits [20] The characteristics of Bafangshan-Erlihe ore deposit fit to both hydrothermal sedimentary oredeposits [11] and orogenic ore deposits [12] but no obviousevidence can directly exclude metallogenic sources fromeither hydrothermal seafloor (and subseafloor) precipitationor deposition from orogenic fluidsThus the distribution andcompositional characteristics of the siliceous rocks may helpclarifying the geological evolution and metallogenesis in thearea
The Bafangshan-Erlihe SEDEX deposit is of importanceto understand the mechanism of hydrothermal water evo-lution in the paleo-ocean It is located in the Fengxian-Taibai (or Fengtai) area [5] and is characterized by closerelationships between the metallogenesis and depositionof siliceous strata Previous work [1 4] considered thesiliceous rocks of the Bafangshan-Erlihe ore deposit to be ofhydrothermal genesis however ignoring the mineralogicalcharacteristics evolution mechanism of the hydrothermalwater and relationship between these siliceous rocks andtheir associated metal sulphides In addition the mechanismof hydrothermal convection necessary for the deposition ofthe siliceous rocks remained uncertain and whether thereare similarities to the published literature [21 22] has to beconfirmedThe aimof this paper is to study the characteristicsof temporal and spatial distribution of the siliceous rocks inthe COB their microfabric and geochemical characteristicsand to present a model that incorporates the contribution
of different geological processes during the deposition ofhydrothermal silica and sulphide
2 Geological Setting andPetrological Characteristics
21 Geological Setting The COB has a complex tectonicevolution evidenced by the diversity in the eastern andwestern Qinling orogenic belts The mainland of the presentChina is originated from the matching of several Neopaleo-zoic landmasses (Figure 1(a)) These blocks are Sino-KoreanSonnen Northern Qiangtang Cathaysian Tarim Yangtzeand so forth The COB is located in the middle of Chinaand separated the Sino-Korean craton and Yangtze blockon its north and south (Figure 1(b)) This orogenic belt ismainly made up of Kunlun Qilian Qinling Dabie and Suluorogenic belts and passes through the provinces of QinghaiGansu Shanxi Henan and Anhui China in northwestdirection (Figure 1(b)) The main feature of the COB isthe Qinling collisional orogenic belt [23] The geologicalevolution of theQingling orogenic belt can be divided into theformation of Precambrian basement from Neoarchaean toMesoproterozoic (Ar
3-Pt2) evolution of plate tectonics from
Neoproterozoic to Middle Triassic (Pt3-T2) and intraconti-
nental orogeny from Mesozoic (Late Triassic) to Cenozoic(Mz(T
3)-Kz) [24] Although thewhole ocean basin ofwestern
Qinling starts from the Early Cambrian rift basin and endsup with the Triassic orogeny [25] the tectonic diversityof geological evolution contributed to the subdivision of awestern section and an eastern section within the Qinlingorogenic belt [26 27] The three tectonic cycles of opening-closing for the western Qinling are Early Cambrian sim EarlyDevonianMiddle Devonian sim Late Carboniferous and EarlyPermian sim Late Triassic [27] while the two tectonic phasesof opening-closing for eastern Qinling are Early Cambrian
The Scientific World Journal 3
Xiangzihe-Huangbaiyuan fault
Xiushiyan-Guanyinxia faultWangjialeng-Erlangba fault
Daohuigou-Tuoliyuan fault
tluafuokgnaiJ-gnailnaiduiJ
Hanzhong
Baoji
Taibai
North Chinaplate
Fengxian
Taibai igneous rock
N
Guji
Hekou
Fengxian
XinghongpuGuchaheJiudianliang
Guochang
YinjiabaXiba igneous rock
Wangjialeng
Bafangshan-Erlihe area
Erlangping
Xiangzihe
Jiangkou
Geological boundury
FaultSynclinorum
Pb-Zn ore deposit
Mesozoic igneous rock
Triassic microclastic rock
Cretaceous clastic rock
Permian phyllite limestone carbonaceous siliceous rock
Devonian clastic rock carbonate rock siliceous rock
Precambrian volcanic rock and sedimentary rock
Carboniferous phyllite limestone siliceous rock
Silurian clastic rock siliceous limestone phyllite slate
0 10(km)
Figure 3
106∘ 107∘ 108∘
33∘
34∘
Lueyang
Figure 2 Geological sketch-map of the Fengxian-Taibai ore concentration area (after-[33])
sim Late Silurian and Early Devonian sim Late Triassic [26]It is considered that the ocean basin of the COB is neriticin the Middle Permian [28] but whether there is a similargeographical pattern in the Devonian will be examinedthrough the present study of the siliceous rocks from theFengtai area
The Fengtai metallogenic area is located in the centralpart of the western Qinling orogenic belt In the Fengtaimetallogenic area (Figure 2) there are many polymetallic oredeposits in the Bafangshan-Erlihe Bijiashan DengjiashanQiandongshan Yinmusi Shoubanya and Fengya areas Thetectonic frame is trending in NW direction as expressedby the Guchahe-Yinjiaba multiple downfolds and largefaults (eg Xiushiyan-Guanyinxia Wangjialeng-Erlangbaand Daohuigou-Tuoliyuan faults)The Fengtai area is locatedin the pull-apart basin of the northern region of Qinlingmicroplate whose southern and northern boundaries areLiuba peel thrust faults and the Shangzhou-Danfeng faultrespectively Additionally it is a secondary basin controlledby cross-basin synfaults [31] which are named Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyanzhenfaults [1 32]
There is a diversity of sedimentary strata in the Fengtaiarea The siliceous rocks associated with the metallogenesisof the Bafangshan-Erlihe ore deposit are mainly concen-trated in the Middle-Upper Devonian strata (Figure 2) TheMiddle-Upper Devonian strata include clastic rocks of theWangjialeng Formation carbonate rocks of the GudaolingFormationmetamorphic debris with interlayers of carbonaterocks of the Xinghongpu Formation and fine-grained clasticrocks of Jiuliping Formation
N
Bafangshan ore segment
Erlihe ore segment
Strata boundry
Fault
Pb-Zn orebody withorehosted siliceous rock
Cu orebody withorehosted siliceous rock
Diorite dyke
AB
C
Concealed orebody
0 200(m)
D3
D2
D3x22 phyllite limestone
D3x11 siliceous rock
D3x21 chlorite-sericite phyllite
D2g2 carbonate rockD3x1
1 phyllite
D3x12 sericite phyllite
A998400
B 998400
C998400
Figure 3 Geologicalmap of the Bafangshan-Erlihe area (after-[33])
22 Geology of Ore Deposit The Bafangshan-Erlihe oredeposit is one of the significant hydrothermal ore depositsin the Fengtai metallogenic area located in the northwesternFengtai basin (Figure 1) The strata belong to the MiddleDevonian Gudaoling Formation (D2) and to the UpperDevonian Xinghongpu Formation D3 (Figure 3)
The Upper Devonian Xinghongpu Formation is made upof clastic rocks (siltstones and sandstones) with some foliated
4 The Scientific World Journal
limestones [32 34] The strata of the Xinghongpu Formationare divided into three different lithological sections as followsthe first section of the Xinghongpu Formation includesarenaceous phyllite the second section of the XinghongpuFormation is comprised of carbon-bearing phyllite andsericitic phyllite the third section is mainly composed ofbanded lamellar limestone and calcitic-sericitic-phyllite Inthe bottom of the first section there are ferrodolomitesericitic phyllite and siliceous rocks which were the countryrocks of the Cu-Pb-Zn orebody
The Middle Devonian Gudaoling Formation occupiesthe entire Bafangshan-Erlihe ore deposit (Figure 3) Thisformation extends downward to the lower part beneath theearthrsquos surface to make up the core of the Bafangshan-Erliheanticlinal This formation is divided into two parts the firstpart is a clastic series including sandstones and shales and thesecond part is composed of carbonate rocks
The hydrothermal sedimentary sequence is located inthe interface between the Middle Devonian Gudaoling For-mation and the Upper Devonian Xinghongpu FormationThis sedimentary sequence is composed of siliceous rockssiliceous ferrodolomites silicified limestones and lime-stonesThe stratumof the siliceous rocks ranging from 1m to30m belongs to the ore-bearing strataThere are boudinagedsiliceous rocks and aggregates of siliceous ankerite in the ore-bearing strata The siliceous rocks are exposed on the surfaceat the Bafangshan areawhereas they extend downwards to theErlihe area In addition some of the orebodies are hosted inlimestones or ferrodolomites
The Bafangshan-Erlihe ore region is intensively foldedand faulted (Figure 3) The Cu-Pb-Zn orebodies are con-trolled by the Bafangshan-Erlihe anticline There are twotypes of faults the normal faults striking NNE-SSW andNNW-SSE are widely distributed across the study area withan angle of dip of 70∘ the compression-shear faults strikingEW with hades ranging from 48∘ to 73∘The area is character-ized by a weak magmatic activity related to the emplacementof some dikes along NE-striking normal faults The dykesinclude quartz-porphyries and quartz-diorite-porphyries
23 Distribution of Orebody The Cu-Pb-Zn ore depositsin the Bafangshan-Erlihe area are controlled by anticlines(Figure 3) [32 34] The Bafangshan-Erlihe ore deposit isdivided into two segments which are located in the Bafang-shan and Erlihe areas Because of denudation at the top ofthe anticlines the orebodies of the Bafangshan segment areexposed at the surface In the core of the anticlines the orestrata are distributed with the shape of an irregular circlearound the limestone They stretch eastward and becomeunderground toward the Erlihe ore area In the Erlihe areathe orebodies are concealed at a depth of up to 800 metersThe proven orebodies are mostly developed on the arch bendof the anticlines in longitudinal profile (Figures 3 and 4)Orebodies are stratabound and generally contact with theadjoining country rocks conformably The primary orebodyis consistent with the construction of the anticlines and it ismore than 2300 meters in length and ranges from 100 metersto 300 meters in width [34] On the incline the primary
Pb-Zn ore body with ore-hosted siliceous rockCu ore body with ore-hosted siliceous rock
Discontiguous siliceous rock some parts feebly mineralized
1700m
1700m1800m
1800m
1700m
1600m
1500m
1400m
289 ∘45 998400
199∘45998400
A-A998400
B-B998400
C-C998400
Figure 4 Cross-sections of ore body and siliceous rock in theBafangshan-Erlihe Cu-Pb-Zn ore deposit For location see Figure 3(After-[12])
orebodies stretch downwards and becomenarrower fromeastto west
There are obvious horizontal and vertical mineralizationcharacteristics (Figure 4) At the Bafangshan ore deposit theore grade decreases with depth [34 35] thus all copper leadand zinc are distributed in the upper part of the depositAlong strike the Bafangshan ore deposit generally extendsfrom east to west and can be grouped into the east middleand west parts without clear mineralization boundariesbetween them [35] The eastern part is characterized bymineralised zones of copper lead and zinc dominated bychalcopyrite sphalerite and galena respectively The middlepart is mainly composed of lead and zinc sulphides (eggalena and sphalerite) The main mineralization in the west-ern part consists of chalcopyrite with traces of galena andsphalerite
24 Petrological Characteristics In the Bafangshan-Erlihe oredeposit mineralization is hosted in siliceous rock and fer-rodolomite breccias The breccias are cemented by chalcopy-rite (Figure 5(a)) galena sphalerite and pyrite Some of theferrodolomite-bearing siliceous rocks are oxidised and dis-play alternating layers of siliceous rocks and ferrodolomites(Figure 5(b)) The ores exhibit brecciated stockwork andlamellar structures The pure siliceous rocks without min-eralisation are grey compacted and hard with brecciatedmassive (Figure 5(c)) and banded structures (Figure 5(b))Microscopically the siliceous rocks are composed of finelycrystalline quartz forming close-packed or interlocking tex-tures (Figure 5(d)) which are similar to slightly recrystallizedsiliceous rocks of hydrothermal genesis [36] Minor idiomor-phic carbonateminerals are also present in the siliceous rocks(Figure 5(e)) In addition there are also some recrystallizedquartz grains with much larger grain sizes (Figure 5(f))surrounded by the finely crystalline quartz grains in thematrix
The Scientific World Journal 5
Chalcopyrite
Covelline
(a)
Ferrodolomite
Silica
(b)
(c)
04mm
(d)
Calc
02mm
(e)
QtzRQtzR
QtzR
04mm
(f)
Figure 5 Ores and siliceous rocks from the Bafangshan-Erlihe ore deposit ((a) copper ore (b) ferrodolomite-bearing siliceous rocks withlamellar structures the lamellae of the ferrodolomite were oxidised (c) pure siliceous rock (d) finely crystalline siliceous rock under parallelnicols (e) idiomorphic calcite in parallel nicols (f) recrystallized quartz in crossed nicols Calc-Calcite QtzR-recrystallized quartz)
3 Samples and Experiments
During the pretreatment processes fresh samples (includingore-hosting siliceous rocks and pure siliceous rocks with-out mineralization) of Bafangshan-Erlihe polymetallic oredeposit were selected cleaned in ultrapure water dried andthen divided into two groups namely one polished into thinsections (le003mm) and the other crushed into grains of03 cm-equivalent spherical diameter in a clean corundumjaw-breaker A subsample from the latter group was selectedcleaned redried and ground to 0075mm diameter particlesin an agate ball mill (NO XQN-500x4) Additionally all the
ore-hosting siliceous rocks were repeatedly separated fromthe ore to ensure their purification
The pretreatment and analysis of each samplersquos majorelements were carried out in Guilinrsquos Research Instituteof Geology and Mineral Resource Test Centre and theresults are shown in Table 1 The SiO
2content was analysed
by potassium hexafluorosilicate titration to an accuracy ofbetween 1 and 15 The Al
2O3constituents were analysed
with ultraviolet spectrophotometry (to contents below 1by mass using instrument type UV-120-02 at an accu-racy of 05 to 1) or by EDTA titration (for contentsabove 1 to an accuracy of 15) The Na
2O K2O and
6 The Scientific World Journal
Table1Major
elementanalysis
data(
)for
siliceous
rocksfrom
Bafang
shan-Erlihe
area
NO
Descriptio
nof
samples
SiO
2TiO
2Al 2O
3Fe
2O3
FeO
MnO
MgO
CaO
Na 2O
K 2O
P 2O
5LO
ITo
tal
FE001
Siliceous
rock
with
outm
ineralization
7108
000
054
019
108
008
088
1384
001
007
006
1213
9996
FE002
Siliceous
rock
with
outm
ineralization
8916
006
226
010
096
006
077
179
003
057
002
310
9887
FE003
Siliceous
rock
with
outm
ineralization
8113
001
057
023
238
010
147
625
001
011
003
749
9978
FE00
4Siliceous
rock
with
outm
ineralization
7557
007
196
028
388
012
189
586
003
057
003
885
9911
FE005
Siliceous
rock
with
outm
ineralization
7564
000
019
049
407
013
225
686
001
005
000
975
9943
FE00
6Siliceous
rock
with
outm
ineralization
7456
022
555
051
240
011
135
606
007
161
006
748
9997
FE007
Siliceous
rock
with
outm
ineralization
8308
006
173
058
264
008
117
409
002
045
002
576
9968
FE008
Siliceous
rock
with
outm
ineralization
9530
005
098
006
118
012
028
117
015
010
001
059
9997
FB001
Siliceous
rock
with
outm
ineralization
8240
007
288
018
218
010
288
256
004
085
005
464
9883
FB002
Siliceous
rock
with
outm
ineralization
8127
009
400
386
178
012
106
164
007
109
009
526
10033
FB003
Siliceous
rock
with
outm
ineralization
8688
003
123
017
233
012
118
328
002
032
006
496
10058
FB00
4Siliceous
rock
with
outm
ineralization
8884
008
212
065
048
002
050
356
008
066
005
361
10065
FB005
Siliceous
rock
with
outm
ineralization
8192
013
387
246
185
005
133
346
007
108
004
454
10080
FB00
6Siliceous
rock
with
outm
ineralization
9204
004
215
035
166
008
113
072
006
068
006
176
10073
Aver
mdash8410
007
218
069
183
009
114
401
005
059
004
515
9994
lowastlowastSamples
ofFB
001toFB
006arefrom
literature[
1]
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
2 The Scientific World Journal
Landmass
SN
SKTA
KK
CT
YZ
NQ
LowlandAral seaNeritic facies
Highland Abyssal facies
Figure 1(b)
N30∘
N60∘
(a)
Central orogenic belt
N0 300(km)
Primary tectonic sutureSecondary tectonic suture zoneAltun Tagh fault zoneBoundary of EQL and WQL
City
Wuhan
Xian
Lanzhou
Hanzhong
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC(SKC)
Figure 2
Urumqi
zone
1000 km
N34∘
E108∘ Fengtai
(b)
Figure 1 Geographical map and geological sketch of COB and the associated area ((a)mdashreconstruction map of the Middle-Permian paleo-continents [28] (b)mdashgeological framework of central orogenic belt [29 30] TA Tarim KK Karakum SN Sonnen SK Sino-Korean YZYangtze NQ Northern Qiangtang CT Cathaysian EKL Eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL WesternQinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block and DBDabie orogenic belt)
are regarded to be of orogenic type and formed during theorogeny [12] As one of the typical hydrothermal ore depositsin the COB the Bafangshan-Erlihe SEDEX deposit is a strata-bound Cu-Pb-Zn deposit with siliceous strata hosting andsurrounding ores [5] The siliceous rocks and associatedmineralisation are slightly modified during subsequent oro-genic processes [15 18 19] resulting in redistribution ofmetal sulphides in fissures as commonly observed in oro-genic type deposits [20] The characteristics of Bafangshan-Erlihe ore deposit fit to both hydrothermal sedimentary oredeposits [11] and orogenic ore deposits [12] but no obviousevidence can directly exclude metallogenic sources fromeither hydrothermal seafloor (and subseafloor) precipitationor deposition from orogenic fluidsThus the distribution andcompositional characteristics of the siliceous rocks may helpclarifying the geological evolution and metallogenesis in thearea
The Bafangshan-Erlihe SEDEX deposit is of importanceto understand the mechanism of hydrothermal water evo-lution in the paleo-ocean It is located in the Fengxian-Taibai (or Fengtai) area [5] and is characterized by closerelationships between the metallogenesis and depositionof siliceous strata Previous work [1 4] considered thesiliceous rocks of the Bafangshan-Erlihe ore deposit to be ofhydrothermal genesis however ignoring the mineralogicalcharacteristics evolution mechanism of the hydrothermalwater and relationship between these siliceous rocks andtheir associated metal sulphides In addition the mechanismof hydrothermal convection necessary for the deposition ofthe siliceous rocks remained uncertain and whether thereare similarities to the published literature [21 22] has to beconfirmedThe aimof this paper is to study the characteristicsof temporal and spatial distribution of the siliceous rocks inthe COB their microfabric and geochemical characteristicsand to present a model that incorporates the contribution
of different geological processes during the deposition ofhydrothermal silica and sulphide
2 Geological Setting andPetrological Characteristics
21 Geological Setting The COB has a complex tectonicevolution evidenced by the diversity in the eastern andwestern Qinling orogenic belts The mainland of the presentChina is originated from the matching of several Neopaleo-zoic landmasses (Figure 1(a)) These blocks are Sino-KoreanSonnen Northern Qiangtang Cathaysian Tarim Yangtzeand so forth The COB is located in the middle of Chinaand separated the Sino-Korean craton and Yangtze blockon its north and south (Figure 1(b)) This orogenic belt ismainly made up of Kunlun Qilian Qinling Dabie and Suluorogenic belts and passes through the provinces of QinghaiGansu Shanxi Henan and Anhui China in northwestdirection (Figure 1(b)) The main feature of the COB isthe Qinling collisional orogenic belt [23] The geologicalevolution of theQingling orogenic belt can be divided into theformation of Precambrian basement from Neoarchaean toMesoproterozoic (Ar
3-Pt2) evolution of plate tectonics from
Neoproterozoic to Middle Triassic (Pt3-T2) and intraconti-
nental orogeny from Mesozoic (Late Triassic) to Cenozoic(Mz(T
3)-Kz) [24] Although thewhole ocean basin ofwestern
Qinling starts from the Early Cambrian rift basin and endsup with the Triassic orogeny [25] the tectonic diversityof geological evolution contributed to the subdivision of awestern section and an eastern section within the Qinlingorogenic belt [26 27] The three tectonic cycles of opening-closing for the western Qinling are Early Cambrian sim EarlyDevonianMiddle Devonian sim Late Carboniferous and EarlyPermian sim Late Triassic [27] while the two tectonic phasesof opening-closing for eastern Qinling are Early Cambrian
The Scientific World Journal 3
Xiangzihe-Huangbaiyuan fault
Xiushiyan-Guanyinxia faultWangjialeng-Erlangba fault
Daohuigou-Tuoliyuan fault
tluafuokgnaiJ-gnailnaiduiJ
Hanzhong
Baoji
Taibai
North Chinaplate
Fengxian
Taibai igneous rock
N
Guji
Hekou
Fengxian
XinghongpuGuchaheJiudianliang
Guochang
YinjiabaXiba igneous rock
Wangjialeng
Bafangshan-Erlihe area
Erlangping
Xiangzihe
Jiangkou
Geological boundury
FaultSynclinorum
Pb-Zn ore deposit
Mesozoic igneous rock
Triassic microclastic rock
Cretaceous clastic rock
Permian phyllite limestone carbonaceous siliceous rock
Devonian clastic rock carbonate rock siliceous rock
Precambrian volcanic rock and sedimentary rock
Carboniferous phyllite limestone siliceous rock
Silurian clastic rock siliceous limestone phyllite slate
0 10(km)
Figure 3
106∘ 107∘ 108∘
33∘
34∘
Lueyang
Figure 2 Geological sketch-map of the Fengxian-Taibai ore concentration area (after-[33])
sim Late Silurian and Early Devonian sim Late Triassic [26]It is considered that the ocean basin of the COB is neriticin the Middle Permian [28] but whether there is a similargeographical pattern in the Devonian will be examinedthrough the present study of the siliceous rocks from theFengtai area
The Fengtai metallogenic area is located in the centralpart of the western Qinling orogenic belt In the Fengtaimetallogenic area (Figure 2) there are many polymetallic oredeposits in the Bafangshan-Erlihe Bijiashan DengjiashanQiandongshan Yinmusi Shoubanya and Fengya areas Thetectonic frame is trending in NW direction as expressedby the Guchahe-Yinjiaba multiple downfolds and largefaults (eg Xiushiyan-Guanyinxia Wangjialeng-Erlangbaand Daohuigou-Tuoliyuan faults)The Fengtai area is locatedin the pull-apart basin of the northern region of Qinlingmicroplate whose southern and northern boundaries areLiuba peel thrust faults and the Shangzhou-Danfeng faultrespectively Additionally it is a secondary basin controlledby cross-basin synfaults [31] which are named Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyanzhenfaults [1 32]
There is a diversity of sedimentary strata in the Fengtaiarea The siliceous rocks associated with the metallogenesisof the Bafangshan-Erlihe ore deposit are mainly concen-trated in the Middle-Upper Devonian strata (Figure 2) TheMiddle-Upper Devonian strata include clastic rocks of theWangjialeng Formation carbonate rocks of the GudaolingFormationmetamorphic debris with interlayers of carbonaterocks of the Xinghongpu Formation and fine-grained clasticrocks of Jiuliping Formation
N
Bafangshan ore segment
Erlihe ore segment
Strata boundry
Fault
Pb-Zn orebody withorehosted siliceous rock
Cu orebody withorehosted siliceous rock
Diorite dyke
AB
C
Concealed orebody
0 200(m)
D3
D2
D3x22 phyllite limestone
D3x11 siliceous rock
D3x21 chlorite-sericite phyllite
D2g2 carbonate rockD3x1
1 phyllite
D3x12 sericite phyllite
A998400
B 998400
C998400
Figure 3 Geologicalmap of the Bafangshan-Erlihe area (after-[33])
22 Geology of Ore Deposit The Bafangshan-Erlihe oredeposit is one of the significant hydrothermal ore depositsin the Fengtai metallogenic area located in the northwesternFengtai basin (Figure 1) The strata belong to the MiddleDevonian Gudaoling Formation (D2) and to the UpperDevonian Xinghongpu Formation D3 (Figure 3)
The Upper Devonian Xinghongpu Formation is made upof clastic rocks (siltstones and sandstones) with some foliated
4 The Scientific World Journal
limestones [32 34] The strata of the Xinghongpu Formationare divided into three different lithological sections as followsthe first section of the Xinghongpu Formation includesarenaceous phyllite the second section of the XinghongpuFormation is comprised of carbon-bearing phyllite andsericitic phyllite the third section is mainly composed ofbanded lamellar limestone and calcitic-sericitic-phyllite Inthe bottom of the first section there are ferrodolomitesericitic phyllite and siliceous rocks which were the countryrocks of the Cu-Pb-Zn orebody
The Middle Devonian Gudaoling Formation occupiesthe entire Bafangshan-Erlihe ore deposit (Figure 3) Thisformation extends downward to the lower part beneath theearthrsquos surface to make up the core of the Bafangshan-Erliheanticlinal This formation is divided into two parts the firstpart is a clastic series including sandstones and shales and thesecond part is composed of carbonate rocks
The hydrothermal sedimentary sequence is located inthe interface between the Middle Devonian Gudaoling For-mation and the Upper Devonian Xinghongpu FormationThis sedimentary sequence is composed of siliceous rockssiliceous ferrodolomites silicified limestones and lime-stonesThe stratumof the siliceous rocks ranging from 1m to30m belongs to the ore-bearing strataThere are boudinagedsiliceous rocks and aggregates of siliceous ankerite in the ore-bearing strata The siliceous rocks are exposed on the surfaceat the Bafangshan areawhereas they extend downwards to theErlihe area In addition some of the orebodies are hosted inlimestones or ferrodolomites
The Bafangshan-Erlihe ore region is intensively foldedand faulted (Figure 3) The Cu-Pb-Zn orebodies are con-trolled by the Bafangshan-Erlihe anticline There are twotypes of faults the normal faults striking NNE-SSW andNNW-SSE are widely distributed across the study area withan angle of dip of 70∘ the compression-shear faults strikingEW with hades ranging from 48∘ to 73∘The area is character-ized by a weak magmatic activity related to the emplacementof some dikes along NE-striking normal faults The dykesinclude quartz-porphyries and quartz-diorite-porphyries
23 Distribution of Orebody The Cu-Pb-Zn ore depositsin the Bafangshan-Erlihe area are controlled by anticlines(Figure 3) [32 34] The Bafangshan-Erlihe ore deposit isdivided into two segments which are located in the Bafang-shan and Erlihe areas Because of denudation at the top ofthe anticlines the orebodies of the Bafangshan segment areexposed at the surface In the core of the anticlines the orestrata are distributed with the shape of an irregular circlearound the limestone They stretch eastward and becomeunderground toward the Erlihe ore area In the Erlihe areathe orebodies are concealed at a depth of up to 800 metersThe proven orebodies are mostly developed on the arch bendof the anticlines in longitudinal profile (Figures 3 and 4)Orebodies are stratabound and generally contact with theadjoining country rocks conformably The primary orebodyis consistent with the construction of the anticlines and it ismore than 2300 meters in length and ranges from 100 metersto 300 meters in width [34] On the incline the primary
Pb-Zn ore body with ore-hosted siliceous rockCu ore body with ore-hosted siliceous rock
Discontiguous siliceous rock some parts feebly mineralized
1700m
1700m1800m
1800m
1700m
1600m
1500m
1400m
289 ∘45 998400
199∘45998400
A-A998400
B-B998400
C-C998400
Figure 4 Cross-sections of ore body and siliceous rock in theBafangshan-Erlihe Cu-Pb-Zn ore deposit For location see Figure 3(After-[12])
orebodies stretch downwards and becomenarrower fromeastto west
There are obvious horizontal and vertical mineralizationcharacteristics (Figure 4) At the Bafangshan ore deposit theore grade decreases with depth [34 35] thus all copper leadand zinc are distributed in the upper part of the depositAlong strike the Bafangshan ore deposit generally extendsfrom east to west and can be grouped into the east middleand west parts without clear mineralization boundariesbetween them [35] The eastern part is characterized bymineralised zones of copper lead and zinc dominated bychalcopyrite sphalerite and galena respectively The middlepart is mainly composed of lead and zinc sulphides (eggalena and sphalerite) The main mineralization in the west-ern part consists of chalcopyrite with traces of galena andsphalerite
24 Petrological Characteristics In the Bafangshan-Erlihe oredeposit mineralization is hosted in siliceous rock and fer-rodolomite breccias The breccias are cemented by chalcopy-rite (Figure 5(a)) galena sphalerite and pyrite Some of theferrodolomite-bearing siliceous rocks are oxidised and dis-play alternating layers of siliceous rocks and ferrodolomites(Figure 5(b)) The ores exhibit brecciated stockwork andlamellar structures The pure siliceous rocks without min-eralisation are grey compacted and hard with brecciatedmassive (Figure 5(c)) and banded structures (Figure 5(b))Microscopically the siliceous rocks are composed of finelycrystalline quartz forming close-packed or interlocking tex-tures (Figure 5(d)) which are similar to slightly recrystallizedsiliceous rocks of hydrothermal genesis [36] Minor idiomor-phic carbonateminerals are also present in the siliceous rocks(Figure 5(e)) In addition there are also some recrystallizedquartz grains with much larger grain sizes (Figure 5(f))surrounded by the finely crystalline quartz grains in thematrix
The Scientific World Journal 5
Chalcopyrite
Covelline
(a)
Ferrodolomite
Silica
(b)
(c)
04mm
(d)
Calc
02mm
(e)
QtzRQtzR
QtzR
04mm
(f)
Figure 5 Ores and siliceous rocks from the Bafangshan-Erlihe ore deposit ((a) copper ore (b) ferrodolomite-bearing siliceous rocks withlamellar structures the lamellae of the ferrodolomite were oxidised (c) pure siliceous rock (d) finely crystalline siliceous rock under parallelnicols (e) idiomorphic calcite in parallel nicols (f) recrystallized quartz in crossed nicols Calc-Calcite QtzR-recrystallized quartz)
3 Samples and Experiments
During the pretreatment processes fresh samples (includingore-hosting siliceous rocks and pure siliceous rocks with-out mineralization) of Bafangshan-Erlihe polymetallic oredeposit were selected cleaned in ultrapure water dried andthen divided into two groups namely one polished into thinsections (le003mm) and the other crushed into grains of03 cm-equivalent spherical diameter in a clean corundumjaw-breaker A subsample from the latter group was selectedcleaned redried and ground to 0075mm diameter particlesin an agate ball mill (NO XQN-500x4) Additionally all the
ore-hosting siliceous rocks were repeatedly separated fromthe ore to ensure their purification
The pretreatment and analysis of each samplersquos majorelements were carried out in Guilinrsquos Research Instituteof Geology and Mineral Resource Test Centre and theresults are shown in Table 1 The SiO
2content was analysed
by potassium hexafluorosilicate titration to an accuracy ofbetween 1 and 15 The Al
2O3constituents were analysed
with ultraviolet spectrophotometry (to contents below 1by mass using instrument type UV-120-02 at an accu-racy of 05 to 1) or by EDTA titration (for contentsabove 1 to an accuracy of 15) The Na
2O K2O and
6 The Scientific World Journal
Table1Major
elementanalysis
data(
)for
siliceous
rocksfrom
Bafang
shan-Erlihe
area
NO
Descriptio
nof
samples
SiO
2TiO
2Al 2O
3Fe
2O3
FeO
MnO
MgO
CaO
Na 2O
K 2O
P 2O
5LO
ITo
tal
FE001
Siliceous
rock
with
outm
ineralization
7108
000
054
019
108
008
088
1384
001
007
006
1213
9996
FE002
Siliceous
rock
with
outm
ineralization
8916
006
226
010
096
006
077
179
003
057
002
310
9887
FE003
Siliceous
rock
with
outm
ineralization
8113
001
057
023
238
010
147
625
001
011
003
749
9978
FE00
4Siliceous
rock
with
outm
ineralization
7557
007
196
028
388
012
189
586
003
057
003
885
9911
FE005
Siliceous
rock
with
outm
ineralization
7564
000
019
049
407
013
225
686
001
005
000
975
9943
FE00
6Siliceous
rock
with
outm
ineralization
7456
022
555
051
240
011
135
606
007
161
006
748
9997
FE007
Siliceous
rock
with
outm
ineralization
8308
006
173
058
264
008
117
409
002
045
002
576
9968
FE008
Siliceous
rock
with
outm
ineralization
9530
005
098
006
118
012
028
117
015
010
001
059
9997
FB001
Siliceous
rock
with
outm
ineralization
8240
007
288
018
218
010
288
256
004
085
005
464
9883
FB002
Siliceous
rock
with
outm
ineralization
8127
009
400
386
178
012
106
164
007
109
009
526
10033
FB003
Siliceous
rock
with
outm
ineralization
8688
003
123
017
233
012
118
328
002
032
006
496
10058
FB00
4Siliceous
rock
with
outm
ineralization
8884
008
212
065
048
002
050
356
008
066
005
361
10065
FB005
Siliceous
rock
with
outm
ineralization
8192
013
387
246
185
005
133
346
007
108
004
454
10080
FB00
6Siliceous
rock
with
outm
ineralization
9204
004
215
035
166
008
113
072
006
068
006
176
10073
Aver
mdash8410
007
218
069
183
009
114
401
005
059
004
515
9994
lowastlowastSamples
ofFB
001toFB
006arefrom
literature[
1]
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 3
Xiangzihe-Huangbaiyuan fault
Xiushiyan-Guanyinxia faultWangjialeng-Erlangba fault
Daohuigou-Tuoliyuan fault
tluafuokgnaiJ-gnailnaiduiJ
Hanzhong
Baoji
Taibai
North Chinaplate
Fengxian
Taibai igneous rock
N
Guji
Hekou
Fengxian
XinghongpuGuchaheJiudianliang
Guochang
YinjiabaXiba igneous rock
Wangjialeng
Bafangshan-Erlihe area
Erlangping
Xiangzihe
Jiangkou
Geological boundury
FaultSynclinorum
Pb-Zn ore deposit
Mesozoic igneous rock
Triassic microclastic rock
Cretaceous clastic rock
Permian phyllite limestone carbonaceous siliceous rock
Devonian clastic rock carbonate rock siliceous rock
Precambrian volcanic rock and sedimentary rock
Carboniferous phyllite limestone siliceous rock
Silurian clastic rock siliceous limestone phyllite slate
0 10(km)
Figure 3
106∘ 107∘ 108∘
33∘
34∘
Lueyang
Figure 2 Geological sketch-map of the Fengxian-Taibai ore concentration area (after-[33])
sim Late Silurian and Early Devonian sim Late Triassic [26]It is considered that the ocean basin of the COB is neriticin the Middle Permian [28] but whether there is a similargeographical pattern in the Devonian will be examinedthrough the present study of the siliceous rocks from theFengtai area
The Fengtai metallogenic area is located in the centralpart of the western Qinling orogenic belt In the Fengtaimetallogenic area (Figure 2) there are many polymetallic oredeposits in the Bafangshan-Erlihe Bijiashan DengjiashanQiandongshan Yinmusi Shoubanya and Fengya areas Thetectonic frame is trending in NW direction as expressedby the Guchahe-Yinjiaba multiple downfolds and largefaults (eg Xiushiyan-Guanyinxia Wangjialeng-Erlangbaand Daohuigou-Tuoliyuan faults)The Fengtai area is locatedin the pull-apart basin of the northern region of Qinlingmicroplate whose southern and northern boundaries areLiuba peel thrust faults and the Shangzhou-Danfeng faultrespectively Additionally it is a secondary basin controlledby cross-basin synfaults [31] which are named Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyanzhenfaults [1 32]
There is a diversity of sedimentary strata in the Fengtaiarea The siliceous rocks associated with the metallogenesisof the Bafangshan-Erlihe ore deposit are mainly concen-trated in the Middle-Upper Devonian strata (Figure 2) TheMiddle-Upper Devonian strata include clastic rocks of theWangjialeng Formation carbonate rocks of the GudaolingFormationmetamorphic debris with interlayers of carbonaterocks of the Xinghongpu Formation and fine-grained clasticrocks of Jiuliping Formation
N
Bafangshan ore segment
Erlihe ore segment
Strata boundry
Fault
Pb-Zn orebody withorehosted siliceous rock
Cu orebody withorehosted siliceous rock
Diorite dyke
AB
C
Concealed orebody
0 200(m)
D3
D2
D3x22 phyllite limestone
D3x11 siliceous rock
D3x21 chlorite-sericite phyllite
D2g2 carbonate rockD3x1
1 phyllite
D3x12 sericite phyllite
A998400
B 998400
C998400
Figure 3 Geologicalmap of the Bafangshan-Erlihe area (after-[33])
22 Geology of Ore Deposit The Bafangshan-Erlihe oredeposit is one of the significant hydrothermal ore depositsin the Fengtai metallogenic area located in the northwesternFengtai basin (Figure 1) The strata belong to the MiddleDevonian Gudaoling Formation (D2) and to the UpperDevonian Xinghongpu Formation D3 (Figure 3)
The Upper Devonian Xinghongpu Formation is made upof clastic rocks (siltstones and sandstones) with some foliated
4 The Scientific World Journal
limestones [32 34] The strata of the Xinghongpu Formationare divided into three different lithological sections as followsthe first section of the Xinghongpu Formation includesarenaceous phyllite the second section of the XinghongpuFormation is comprised of carbon-bearing phyllite andsericitic phyllite the third section is mainly composed ofbanded lamellar limestone and calcitic-sericitic-phyllite Inthe bottom of the first section there are ferrodolomitesericitic phyllite and siliceous rocks which were the countryrocks of the Cu-Pb-Zn orebody
The Middle Devonian Gudaoling Formation occupiesthe entire Bafangshan-Erlihe ore deposit (Figure 3) Thisformation extends downward to the lower part beneath theearthrsquos surface to make up the core of the Bafangshan-Erliheanticlinal This formation is divided into two parts the firstpart is a clastic series including sandstones and shales and thesecond part is composed of carbonate rocks
The hydrothermal sedimentary sequence is located inthe interface between the Middle Devonian Gudaoling For-mation and the Upper Devonian Xinghongpu FormationThis sedimentary sequence is composed of siliceous rockssiliceous ferrodolomites silicified limestones and lime-stonesThe stratumof the siliceous rocks ranging from 1m to30m belongs to the ore-bearing strataThere are boudinagedsiliceous rocks and aggregates of siliceous ankerite in the ore-bearing strata The siliceous rocks are exposed on the surfaceat the Bafangshan areawhereas they extend downwards to theErlihe area In addition some of the orebodies are hosted inlimestones or ferrodolomites
The Bafangshan-Erlihe ore region is intensively foldedand faulted (Figure 3) The Cu-Pb-Zn orebodies are con-trolled by the Bafangshan-Erlihe anticline There are twotypes of faults the normal faults striking NNE-SSW andNNW-SSE are widely distributed across the study area withan angle of dip of 70∘ the compression-shear faults strikingEW with hades ranging from 48∘ to 73∘The area is character-ized by a weak magmatic activity related to the emplacementof some dikes along NE-striking normal faults The dykesinclude quartz-porphyries and quartz-diorite-porphyries
23 Distribution of Orebody The Cu-Pb-Zn ore depositsin the Bafangshan-Erlihe area are controlled by anticlines(Figure 3) [32 34] The Bafangshan-Erlihe ore deposit isdivided into two segments which are located in the Bafang-shan and Erlihe areas Because of denudation at the top ofthe anticlines the orebodies of the Bafangshan segment areexposed at the surface In the core of the anticlines the orestrata are distributed with the shape of an irregular circlearound the limestone They stretch eastward and becomeunderground toward the Erlihe ore area In the Erlihe areathe orebodies are concealed at a depth of up to 800 metersThe proven orebodies are mostly developed on the arch bendof the anticlines in longitudinal profile (Figures 3 and 4)Orebodies are stratabound and generally contact with theadjoining country rocks conformably The primary orebodyis consistent with the construction of the anticlines and it ismore than 2300 meters in length and ranges from 100 metersto 300 meters in width [34] On the incline the primary
Pb-Zn ore body with ore-hosted siliceous rockCu ore body with ore-hosted siliceous rock
Discontiguous siliceous rock some parts feebly mineralized
1700m
1700m1800m
1800m
1700m
1600m
1500m
1400m
289 ∘45 998400
199∘45998400
A-A998400
B-B998400
C-C998400
Figure 4 Cross-sections of ore body and siliceous rock in theBafangshan-Erlihe Cu-Pb-Zn ore deposit For location see Figure 3(After-[12])
orebodies stretch downwards and becomenarrower fromeastto west
There are obvious horizontal and vertical mineralizationcharacteristics (Figure 4) At the Bafangshan ore deposit theore grade decreases with depth [34 35] thus all copper leadand zinc are distributed in the upper part of the depositAlong strike the Bafangshan ore deposit generally extendsfrom east to west and can be grouped into the east middleand west parts without clear mineralization boundariesbetween them [35] The eastern part is characterized bymineralised zones of copper lead and zinc dominated bychalcopyrite sphalerite and galena respectively The middlepart is mainly composed of lead and zinc sulphides (eggalena and sphalerite) The main mineralization in the west-ern part consists of chalcopyrite with traces of galena andsphalerite
24 Petrological Characteristics In the Bafangshan-Erlihe oredeposit mineralization is hosted in siliceous rock and fer-rodolomite breccias The breccias are cemented by chalcopy-rite (Figure 5(a)) galena sphalerite and pyrite Some of theferrodolomite-bearing siliceous rocks are oxidised and dis-play alternating layers of siliceous rocks and ferrodolomites(Figure 5(b)) The ores exhibit brecciated stockwork andlamellar structures The pure siliceous rocks without min-eralisation are grey compacted and hard with brecciatedmassive (Figure 5(c)) and banded structures (Figure 5(b))Microscopically the siliceous rocks are composed of finelycrystalline quartz forming close-packed or interlocking tex-tures (Figure 5(d)) which are similar to slightly recrystallizedsiliceous rocks of hydrothermal genesis [36] Minor idiomor-phic carbonateminerals are also present in the siliceous rocks(Figure 5(e)) In addition there are also some recrystallizedquartz grains with much larger grain sizes (Figure 5(f))surrounded by the finely crystalline quartz grains in thematrix
The Scientific World Journal 5
Chalcopyrite
Covelline
(a)
Ferrodolomite
Silica
(b)
(c)
04mm
(d)
Calc
02mm
(e)
QtzRQtzR
QtzR
04mm
(f)
Figure 5 Ores and siliceous rocks from the Bafangshan-Erlihe ore deposit ((a) copper ore (b) ferrodolomite-bearing siliceous rocks withlamellar structures the lamellae of the ferrodolomite were oxidised (c) pure siliceous rock (d) finely crystalline siliceous rock under parallelnicols (e) idiomorphic calcite in parallel nicols (f) recrystallized quartz in crossed nicols Calc-Calcite QtzR-recrystallized quartz)
3 Samples and Experiments
During the pretreatment processes fresh samples (includingore-hosting siliceous rocks and pure siliceous rocks with-out mineralization) of Bafangshan-Erlihe polymetallic oredeposit were selected cleaned in ultrapure water dried andthen divided into two groups namely one polished into thinsections (le003mm) and the other crushed into grains of03 cm-equivalent spherical diameter in a clean corundumjaw-breaker A subsample from the latter group was selectedcleaned redried and ground to 0075mm diameter particlesin an agate ball mill (NO XQN-500x4) Additionally all the
ore-hosting siliceous rocks were repeatedly separated fromthe ore to ensure their purification
The pretreatment and analysis of each samplersquos majorelements were carried out in Guilinrsquos Research Instituteof Geology and Mineral Resource Test Centre and theresults are shown in Table 1 The SiO
2content was analysed
by potassium hexafluorosilicate titration to an accuracy ofbetween 1 and 15 The Al
2O3constituents were analysed
with ultraviolet spectrophotometry (to contents below 1by mass using instrument type UV-120-02 at an accu-racy of 05 to 1) or by EDTA titration (for contentsabove 1 to an accuracy of 15) The Na
2O K2O and
6 The Scientific World Journal
Table1Major
elementanalysis
data(
)for
siliceous
rocksfrom
Bafang
shan-Erlihe
area
NO
Descriptio
nof
samples
SiO
2TiO
2Al 2O
3Fe
2O3
FeO
MnO
MgO
CaO
Na 2O
K 2O
P 2O
5LO
ITo
tal
FE001
Siliceous
rock
with
outm
ineralization
7108
000
054
019
108
008
088
1384
001
007
006
1213
9996
FE002
Siliceous
rock
with
outm
ineralization
8916
006
226
010
096
006
077
179
003
057
002
310
9887
FE003
Siliceous
rock
with
outm
ineralization
8113
001
057
023
238
010
147
625
001
011
003
749
9978
FE00
4Siliceous
rock
with
outm
ineralization
7557
007
196
028
388
012
189
586
003
057
003
885
9911
FE005
Siliceous
rock
with
outm
ineralization
7564
000
019
049
407
013
225
686
001
005
000
975
9943
FE00
6Siliceous
rock
with
outm
ineralization
7456
022
555
051
240
011
135
606
007
161
006
748
9997
FE007
Siliceous
rock
with
outm
ineralization
8308
006
173
058
264
008
117
409
002
045
002
576
9968
FE008
Siliceous
rock
with
outm
ineralization
9530
005
098
006
118
012
028
117
015
010
001
059
9997
FB001
Siliceous
rock
with
outm
ineralization
8240
007
288
018
218
010
288
256
004
085
005
464
9883
FB002
Siliceous
rock
with
outm
ineralization
8127
009
400
386
178
012
106
164
007
109
009
526
10033
FB003
Siliceous
rock
with
outm
ineralization
8688
003
123
017
233
012
118
328
002
032
006
496
10058
FB00
4Siliceous
rock
with
outm
ineralization
8884
008
212
065
048
002
050
356
008
066
005
361
10065
FB005
Siliceous
rock
with
outm
ineralization
8192
013
387
246
185
005
133
346
007
108
004
454
10080
FB00
6Siliceous
rock
with
outm
ineralization
9204
004
215
035
166
008
113
072
006
068
006
176
10073
Aver
mdash8410
007
218
069
183
009
114
401
005
059
004
515
9994
lowastlowastSamples
ofFB
001toFB
006arefrom
literature[
1]
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
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[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
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[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
4 The Scientific World Journal
limestones [32 34] The strata of the Xinghongpu Formationare divided into three different lithological sections as followsthe first section of the Xinghongpu Formation includesarenaceous phyllite the second section of the XinghongpuFormation is comprised of carbon-bearing phyllite andsericitic phyllite the third section is mainly composed ofbanded lamellar limestone and calcitic-sericitic-phyllite Inthe bottom of the first section there are ferrodolomitesericitic phyllite and siliceous rocks which were the countryrocks of the Cu-Pb-Zn orebody
The Middle Devonian Gudaoling Formation occupiesthe entire Bafangshan-Erlihe ore deposit (Figure 3) Thisformation extends downward to the lower part beneath theearthrsquos surface to make up the core of the Bafangshan-Erliheanticlinal This formation is divided into two parts the firstpart is a clastic series including sandstones and shales and thesecond part is composed of carbonate rocks
The hydrothermal sedimentary sequence is located inthe interface between the Middle Devonian Gudaoling For-mation and the Upper Devonian Xinghongpu FormationThis sedimentary sequence is composed of siliceous rockssiliceous ferrodolomites silicified limestones and lime-stonesThe stratumof the siliceous rocks ranging from 1m to30m belongs to the ore-bearing strataThere are boudinagedsiliceous rocks and aggregates of siliceous ankerite in the ore-bearing strata The siliceous rocks are exposed on the surfaceat the Bafangshan areawhereas they extend downwards to theErlihe area In addition some of the orebodies are hosted inlimestones or ferrodolomites
The Bafangshan-Erlihe ore region is intensively foldedand faulted (Figure 3) The Cu-Pb-Zn orebodies are con-trolled by the Bafangshan-Erlihe anticline There are twotypes of faults the normal faults striking NNE-SSW andNNW-SSE are widely distributed across the study area withan angle of dip of 70∘ the compression-shear faults strikingEW with hades ranging from 48∘ to 73∘The area is character-ized by a weak magmatic activity related to the emplacementof some dikes along NE-striking normal faults The dykesinclude quartz-porphyries and quartz-diorite-porphyries
23 Distribution of Orebody The Cu-Pb-Zn ore depositsin the Bafangshan-Erlihe area are controlled by anticlines(Figure 3) [32 34] The Bafangshan-Erlihe ore deposit isdivided into two segments which are located in the Bafang-shan and Erlihe areas Because of denudation at the top ofthe anticlines the orebodies of the Bafangshan segment areexposed at the surface In the core of the anticlines the orestrata are distributed with the shape of an irregular circlearound the limestone They stretch eastward and becomeunderground toward the Erlihe ore area In the Erlihe areathe orebodies are concealed at a depth of up to 800 metersThe proven orebodies are mostly developed on the arch bendof the anticlines in longitudinal profile (Figures 3 and 4)Orebodies are stratabound and generally contact with theadjoining country rocks conformably The primary orebodyis consistent with the construction of the anticlines and it ismore than 2300 meters in length and ranges from 100 metersto 300 meters in width [34] On the incline the primary
Pb-Zn ore body with ore-hosted siliceous rockCu ore body with ore-hosted siliceous rock
Discontiguous siliceous rock some parts feebly mineralized
1700m
1700m1800m
1800m
1700m
1600m
1500m
1400m
289 ∘45 998400
199∘45998400
A-A998400
B-B998400
C-C998400
Figure 4 Cross-sections of ore body and siliceous rock in theBafangshan-Erlihe Cu-Pb-Zn ore deposit For location see Figure 3(After-[12])
orebodies stretch downwards and becomenarrower fromeastto west
There are obvious horizontal and vertical mineralizationcharacteristics (Figure 4) At the Bafangshan ore deposit theore grade decreases with depth [34 35] thus all copper leadand zinc are distributed in the upper part of the depositAlong strike the Bafangshan ore deposit generally extendsfrom east to west and can be grouped into the east middleand west parts without clear mineralization boundariesbetween them [35] The eastern part is characterized bymineralised zones of copper lead and zinc dominated bychalcopyrite sphalerite and galena respectively The middlepart is mainly composed of lead and zinc sulphides (eggalena and sphalerite) The main mineralization in the west-ern part consists of chalcopyrite with traces of galena andsphalerite
24 Petrological Characteristics In the Bafangshan-Erlihe oredeposit mineralization is hosted in siliceous rock and fer-rodolomite breccias The breccias are cemented by chalcopy-rite (Figure 5(a)) galena sphalerite and pyrite Some of theferrodolomite-bearing siliceous rocks are oxidised and dis-play alternating layers of siliceous rocks and ferrodolomites(Figure 5(b)) The ores exhibit brecciated stockwork andlamellar structures The pure siliceous rocks without min-eralisation are grey compacted and hard with brecciatedmassive (Figure 5(c)) and banded structures (Figure 5(b))Microscopically the siliceous rocks are composed of finelycrystalline quartz forming close-packed or interlocking tex-tures (Figure 5(d)) which are similar to slightly recrystallizedsiliceous rocks of hydrothermal genesis [36] Minor idiomor-phic carbonateminerals are also present in the siliceous rocks(Figure 5(e)) In addition there are also some recrystallizedquartz grains with much larger grain sizes (Figure 5(f))surrounded by the finely crystalline quartz grains in thematrix
The Scientific World Journal 5
Chalcopyrite
Covelline
(a)
Ferrodolomite
Silica
(b)
(c)
04mm
(d)
Calc
02mm
(e)
QtzRQtzR
QtzR
04mm
(f)
Figure 5 Ores and siliceous rocks from the Bafangshan-Erlihe ore deposit ((a) copper ore (b) ferrodolomite-bearing siliceous rocks withlamellar structures the lamellae of the ferrodolomite were oxidised (c) pure siliceous rock (d) finely crystalline siliceous rock under parallelnicols (e) idiomorphic calcite in parallel nicols (f) recrystallized quartz in crossed nicols Calc-Calcite QtzR-recrystallized quartz)
3 Samples and Experiments
During the pretreatment processes fresh samples (includingore-hosting siliceous rocks and pure siliceous rocks with-out mineralization) of Bafangshan-Erlihe polymetallic oredeposit were selected cleaned in ultrapure water dried andthen divided into two groups namely one polished into thinsections (le003mm) and the other crushed into grains of03 cm-equivalent spherical diameter in a clean corundumjaw-breaker A subsample from the latter group was selectedcleaned redried and ground to 0075mm diameter particlesin an agate ball mill (NO XQN-500x4) Additionally all the
ore-hosting siliceous rocks were repeatedly separated fromthe ore to ensure their purification
The pretreatment and analysis of each samplersquos majorelements were carried out in Guilinrsquos Research Instituteof Geology and Mineral Resource Test Centre and theresults are shown in Table 1 The SiO
2content was analysed
by potassium hexafluorosilicate titration to an accuracy ofbetween 1 and 15 The Al
2O3constituents were analysed
with ultraviolet spectrophotometry (to contents below 1by mass using instrument type UV-120-02 at an accu-racy of 05 to 1) or by EDTA titration (for contentsabove 1 to an accuracy of 15) The Na
2O K2O and
6 The Scientific World Journal
Table1Major
elementanalysis
data(
)for
siliceous
rocksfrom
Bafang
shan-Erlihe
area
NO
Descriptio
nof
samples
SiO
2TiO
2Al 2O
3Fe
2O3
FeO
MnO
MgO
CaO
Na 2O
K 2O
P 2O
5LO
ITo
tal
FE001
Siliceous
rock
with
outm
ineralization
7108
000
054
019
108
008
088
1384
001
007
006
1213
9996
FE002
Siliceous
rock
with
outm
ineralization
8916
006
226
010
096
006
077
179
003
057
002
310
9887
FE003
Siliceous
rock
with
outm
ineralization
8113
001
057
023
238
010
147
625
001
011
003
749
9978
FE00
4Siliceous
rock
with
outm
ineralization
7557
007
196
028
388
012
189
586
003
057
003
885
9911
FE005
Siliceous
rock
with
outm
ineralization
7564
000
019
049
407
013
225
686
001
005
000
975
9943
FE00
6Siliceous
rock
with
outm
ineralization
7456
022
555
051
240
011
135
606
007
161
006
748
9997
FE007
Siliceous
rock
with
outm
ineralization
8308
006
173
058
264
008
117
409
002
045
002
576
9968
FE008
Siliceous
rock
with
outm
ineralization
9530
005
098
006
118
012
028
117
015
010
001
059
9997
FB001
Siliceous
rock
with
outm
ineralization
8240
007
288
018
218
010
288
256
004
085
005
464
9883
FB002
Siliceous
rock
with
outm
ineralization
8127
009
400
386
178
012
106
164
007
109
009
526
10033
FB003
Siliceous
rock
with
outm
ineralization
8688
003
123
017
233
012
118
328
002
032
006
496
10058
FB00
4Siliceous
rock
with
outm
ineralization
8884
008
212
065
048
002
050
356
008
066
005
361
10065
FB005
Siliceous
rock
with
outm
ineralization
8192
013
387
246
185
005
133
346
007
108
004
454
10080
FB00
6Siliceous
rock
with
outm
ineralization
9204
004
215
035
166
008
113
072
006
068
006
176
10073
Aver
mdash8410
007
218
069
183
009
114
401
005
059
004
515
9994
lowastlowastSamples
ofFB
001toFB
006arefrom
literature[
1]
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
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[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
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[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
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[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
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[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
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[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
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[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
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[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
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[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 5
Chalcopyrite
Covelline
(a)
Ferrodolomite
Silica
(b)
(c)
04mm
(d)
Calc
02mm
(e)
QtzRQtzR
QtzR
04mm
(f)
Figure 5 Ores and siliceous rocks from the Bafangshan-Erlihe ore deposit ((a) copper ore (b) ferrodolomite-bearing siliceous rocks withlamellar structures the lamellae of the ferrodolomite were oxidised (c) pure siliceous rock (d) finely crystalline siliceous rock under parallelnicols (e) idiomorphic calcite in parallel nicols (f) recrystallized quartz in crossed nicols Calc-Calcite QtzR-recrystallized quartz)
3 Samples and Experiments
During the pretreatment processes fresh samples (includingore-hosting siliceous rocks and pure siliceous rocks with-out mineralization) of Bafangshan-Erlihe polymetallic oredeposit were selected cleaned in ultrapure water dried andthen divided into two groups namely one polished into thinsections (le003mm) and the other crushed into grains of03 cm-equivalent spherical diameter in a clean corundumjaw-breaker A subsample from the latter group was selectedcleaned redried and ground to 0075mm diameter particlesin an agate ball mill (NO XQN-500x4) Additionally all the
ore-hosting siliceous rocks were repeatedly separated fromthe ore to ensure their purification
The pretreatment and analysis of each samplersquos majorelements were carried out in Guilinrsquos Research Instituteof Geology and Mineral Resource Test Centre and theresults are shown in Table 1 The SiO
2content was analysed
by potassium hexafluorosilicate titration to an accuracy ofbetween 1 and 15 The Al
2O3constituents were analysed
with ultraviolet spectrophotometry (to contents below 1by mass using instrument type UV-120-02 at an accu-racy of 05 to 1) or by EDTA titration (for contentsabove 1 to an accuracy of 15) The Na
2O K2O and
6 The Scientific World Journal
Table1Major
elementanalysis
data(
)for
siliceous
rocksfrom
Bafang
shan-Erlihe
area
NO
Descriptio
nof
samples
SiO
2TiO
2Al 2O
3Fe
2O3
FeO
MnO
MgO
CaO
Na 2O
K 2O
P 2O
5LO
ITo
tal
FE001
Siliceous
rock
with
outm
ineralization
7108
000
054
019
108
008
088
1384
001
007
006
1213
9996
FE002
Siliceous
rock
with
outm
ineralization
8916
006
226
010
096
006
077
179
003
057
002
310
9887
FE003
Siliceous
rock
with
outm
ineralization
8113
001
057
023
238
010
147
625
001
011
003
749
9978
FE00
4Siliceous
rock
with
outm
ineralization
7557
007
196
028
388
012
189
586
003
057
003
885
9911
FE005
Siliceous
rock
with
outm
ineralization
7564
000
019
049
407
013
225
686
001
005
000
975
9943
FE00
6Siliceous
rock
with
outm
ineralization
7456
022
555
051
240
011
135
606
007
161
006
748
9997
FE007
Siliceous
rock
with
outm
ineralization
8308
006
173
058
264
008
117
409
002
045
002
576
9968
FE008
Siliceous
rock
with
outm
ineralization
9530
005
098
006
118
012
028
117
015
010
001
059
9997
FB001
Siliceous
rock
with
outm
ineralization
8240
007
288
018
218
010
288
256
004
085
005
464
9883
FB002
Siliceous
rock
with
outm
ineralization
8127
009
400
386
178
012
106
164
007
109
009
526
10033
FB003
Siliceous
rock
with
outm
ineralization
8688
003
123
017
233
012
118
328
002
032
006
496
10058
FB00
4Siliceous
rock
with
outm
ineralization
8884
008
212
065
048
002
050
356
008
066
005
361
10065
FB005
Siliceous
rock
with
outm
ineralization
8192
013
387
246
185
005
133
346
007
108
004
454
10080
FB00
6Siliceous
rock
with
outm
ineralization
9204
004
215
035
166
008
113
072
006
068
006
176
10073
Aver
mdash8410
007
218
069
183
009
114
401
005
059
004
515
9994
lowastlowastSamples
ofFB
001toFB
006arefrom
literature[
1]
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
6 The Scientific World Journal
Table1Major
elementanalysis
data(
)for
siliceous
rocksfrom
Bafang
shan-Erlihe
area
NO
Descriptio
nof
samples
SiO
2TiO
2Al 2O
3Fe
2O3
FeO
MnO
MgO
CaO
Na 2O
K 2O
P 2O
5LO
ITo
tal
FE001
Siliceous
rock
with
outm
ineralization
7108
000
054
019
108
008
088
1384
001
007
006
1213
9996
FE002
Siliceous
rock
with
outm
ineralization
8916
006
226
010
096
006
077
179
003
057
002
310
9887
FE003
Siliceous
rock
with
outm
ineralization
8113
001
057
023
238
010
147
625
001
011
003
749
9978
FE00
4Siliceous
rock
with
outm
ineralization
7557
007
196
028
388
012
189
586
003
057
003
885
9911
FE005
Siliceous
rock
with
outm
ineralization
7564
000
019
049
407
013
225
686
001
005
000
975
9943
FE00
6Siliceous
rock
with
outm
ineralization
7456
022
555
051
240
011
135
606
007
161
006
748
9997
FE007
Siliceous
rock
with
outm
ineralization
8308
006
173
058
264
008
117
409
002
045
002
576
9968
FE008
Siliceous
rock
with
outm
ineralization
9530
005
098
006
118
012
028
117
015
010
001
059
9997
FB001
Siliceous
rock
with
outm
ineralization
8240
007
288
018
218
010
288
256
004
085
005
464
9883
FB002
Siliceous
rock
with
outm
ineralization
8127
009
400
386
178
012
106
164
007
109
009
526
10033
FB003
Siliceous
rock
with
outm
ineralization
8688
003
123
017
233
012
118
328
002
032
006
496
10058
FB00
4Siliceous
rock
with
outm
ineralization
8884
008
212
065
048
002
050
356
008
066
005
361
10065
FB005
Siliceous
rock
with
outm
ineralization
8192
013
387
246
185
005
133
346
007
108
004
454
10080
FB00
6Siliceous
rock
with
outm
ineralization
9204
004
215
035
166
008
113
072
006
068
006
176
10073
Aver
mdash8410
007
218
069
183
009
114
401
005
059
004
515
9994
lowastlowastSamples
ofFB
001toFB
006arefrom
literature[
1]
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 7
MgO constituents were analysed by atomic absorption spec-troscopy (instrument type HITACHI Z-5000 to an accuracyof 1) The CaO was analysed by atomic absorption spec-troscopy (for contents below 10 using a HITACHIZ-5000instrument with an accuracy of 1) or by EDTA titrationmethod (for contents above 10 at an accuracy of 15)The P
2O5was analysed by ultraviolet spectrophotometry
(for contents below 1 using instrument type UV-120-02 with an accuracy of between 05 and 1) The TiO
2
and MnO constituents were analysed by inductively cou-pled plasma optical emission spectrometry (ICP-OES) withinstruments iCAP 6300 RADIAL and iCAP 6301 RADIALwith accuracies between 05 and 15 The FeO andFe2O3contents were obtained by potassium dichromate
titrationAn inductively coupled plasma mass spectrometer (ICP-
MS Instrument Model PE Elan6000) with an analyticalaccuracy of 1 to 3 was used to test for trace and rareearth elementsThe test solutionwas prepared by acid-solubledissolution and the experiment was performed in accordancewith standard protocols Samples weighing 100mg wereplaced in a sealed Teflon container and lmL of concentratedHF and 03mLof 1 1HNO
3were added Following ultrasonic
oscillation the samples were placed on a hot plate at 150∘Cand then evaporated to dryness remixed with the sameamount of HF and HNO
3 and heated under confinement
for a week (at approximately 100∘C) After evaporationand dissolution in 2mL of 1 1 nitric acid the sample wasadded to an Rh internal standard diluted to 12000th ofits original concentration and tested in the PE Elan6000ICP-MS
Pretreatment for Raman spectroscopy and X-ray diffrac-tion (XRD) analyses was performed in the GuangdongProvincial Key Laboratory of Geological Processes andMineral Resource Survey Raman analysis was performedin the State Key Laboratory of Geological Processes andMineral Resources where the Renishaw RM-1000 inviamicroconfocal instrument was used for the Raman exper-iments with excitation by the 5145 nm line of an Ar+laser Raman spectra were recorded to a resolution of1 cmminus1 from 50 cmminus1 to 1800 cmminus1 An XRD analysis wascarried out in the laboratory of the College of Chemistryand Chemical Engineering of Sun Yat-Sen University XRDdata were collected with an X-ray powder diffractometer(instrument type DMax-2200 vpc) in reflection focusinggeometry mode (Cu K120572 radiation 40 kV30mA scanningspeed 012 s per step step length 002∘ continuous scanningmode) Over a range of 5∘ le scanning angle le 100∘ thedata were postprocessed by JADE-50 software based on theeight highest peaks for the identification of several mineraltypes
The Scanning Electron Microscope (SEM) and EnergyDisperse Spectroscopy (EDS) analysis were carried out by theState Key Laboratory of Chinarsquos University of GeosciencesThe ring scanning electron microscopy instrument was aQuanta 200F environmental scanning electron microscopy-energy spectrum-electron backscatter diffraction system(SEM-EDS) with a resolution of 35 nm and a magnificationof 7 to 1000000
0
10
20
30
40
O D C P JGeological period
Num
ber o
f loc
ality
Pt2 Pt3 120598 S T
Jinni
ng m
ovem
ent
Cale
doni
an m
ovem
ent
Her
cyni
an m
ovem
ent
Indo
sinia
n m
ovem
ent
Yans
han
mov
emen
t
Figure 6 Column diagram of number for localities of siliceousrocks in the COB (data were calculated from literatures [32 37ndash40])
4 Analytical Results
41 Distribution Characteristics The COB trending in aNW direction mainly includes the provinces of QinghaiGansu Shanxi Henan and Anhui China (Figure 1(b)) Inthe present study the numbers and localities of siliceousrocks were calculated from these five provinces based onlocation and formation as themain parametersThe localitiesof the siliceous rocks were calculated from the regional geol-ogy of Zhejiang Jiangxi Hunan Guangdong and Guangxiprovinces [32 37ndash40] In locations where there is a uniformdistribution of siliceous rocks within diverse strata thesesiliceous rocks were separated on the basis of Formation unitAdditionally the Precambrian strata were divided intoMeso-proterozoic and Neoproterozoic (Sinian) strata according tothe literatures [32 37ndash40]
411 Temporal Distribution In theCOB themarine siliceousrocks display a periodic quantitative distribution fromMeso-proterozoic to Jurassic There were positive peaks of theirdistribution number in the Mesoproterozoic Cambrian simOrdovician and Carboniferous sim Permian (Figure 6) Thehighest distribution of siliceous rocks occurs during theMesoproterozoic possibly related with the sustained break-up of Columbia supercontinent with a relatively long geolog-ical history [41 42] The distribution numbers of siliceousrocks increased suddenly at the beginning of Cambrianwhich quite agreed with the beginning of collapse of theQinling orogenic belt [27] Another sudden increase intheir distribution number started from the beginning ofCarboniferous which agreed well with the extensional tec-tonic setting of the whole Qinling orogenic belt [26 27]FromMesoproterozoic to Jurassic there were several suddendecreases in the distribution number of the siliceous rocks
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
8 The Scientific World Journal
which started from the beginning of Sinian Permian andTriassic respectively In the previous study [16 37ndash40]the cratonisation of Rodinia continent took place betweenMesoproterozoic and Neoproterozoic and was contributedby the Jinning orogenyTheCaledonian orogeny took place inLate Silurian in accordance with the decline in distributionnumber of siliceous rocks in Silurian Additionally there wasa sudden decrease in their distribution number in Triassicwhich is in accordance with the Hercynian orogeny at theend ofDevonianDuring the geological evolution ofCOB theextensional tectonics of different tectonic cycles started fromthe beginning of Cambrian and Middle Devonian [26 27]which quite agreed with the sudden increase in distributionnumbers of siliceous rocks Collision of continental platesduring the Jinning Caledonian and Hercynian movementsresulted in compressional regimes and a sudden decrease indistribution numbers of siliceous rocks The siliceous rocksfaded away since theHercynianmovements at the end of Per-mian as well as in the following Indosinian and Yanshanianmovements The marine siliceous rocks disappeared sincethe end of Jurassic due to the regression of the whole COBThus the geological setting was tensional in the tectonic erasof Caledonian (from Sinian to Late Silurian) and Hercynian(fromDevonian to Late Permian) periods when the siliceousrocks had the largest distribution number with the widestdistribution On contrary the Jinning Caledonian Hercy-nian Indosinian and Yanshanian movements contributedto compressional setting and resulted in negative peaks ofdistribution numbers for the siliceous rocks with smallerdistribution scale According to this the widest distributionsof siliceous rocks agreed with the tensional setting whereasthe decreasing numbers of siliceous rock were attributed bythe compressional settings Previous studies show there isperiodic distribution of the siliceous rocks in the Qinlingorogenic belt [25] which quite agree with the present studySo the siliceous rocks were preferential to develop morewidely in tensional settings in the COB and decreasedquantitatively due to the compressional settings
412 Spatial Distribution The siliceous rocks were mainlylocated in the border area of suture zones (Figure 7) Thesiliceous rocks are widely distributed in the central areaof China mainly within the COB and its adjacent areas(Figure 7) Because there was a clear geological diversitybetween eastern and western Qinling orogenic belt [26 27]the COB was divided into eastern section (including easternQinling and Dabie orogenic belts) and western section(including western Kunlun Qilian and Western Qinlingorogenic belts) The siliceous rocks are widely distributedin the Precambrian strata of the COB without a cleardiversity between eastern and western sections (Figure 8(a))In the Eopaleozoic strata (Figure 8(b)) the siliceous rocksare extensively distributed mainly in the eastern COB Thedistribution of Neopaleozoic siliceous rocks is relatively weak(Figure 8(c)) mainly in the western COB Finally the Meso-zoic siliceous rocks was very weakly and sporadically dis-tributed in both eastern and western sections (Figure 8(d))According to the aforementioned the siliceous rocks are
Central orogenic belt
Gansu
N0 300(km)
Primary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Qinghai
Shanxi HenanAnhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DB
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
YZB
NCC (SKC)
1000 km
N34∘
E108∘
Figure 7 Spatial distribution of total siliceous rocks in the COB(EKL eastern Kunlun M-SQ Middle-South Qilian NQ NorthQilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Datasources [32 37ndash40])
variously distributed in time and space along the COB theyare concentrated along the suture zones mainly extending inCaledonian and Hercynian strata in the eastern and westernsections of COB respectively During tectonic evolutionthe suture zones underwent extensional stress with manynormal faults facilitating magma emplacement and transportof hydrothermal fluids [16 43] In the COB siliceous rockswith a more preponderant distribution became youngerfrom the eastern section to the western section which ispossibly attributed to the compressional setting of the easternsection and tensional setting of the western section due tothe Neopaleozoic expanding of the paleo-tethys ocean [27]Additionally the collisional orogeny during the Indosinianand Yanshanian movements contributed to compressionalsettings and therefore resulted in the quantitative reduce ofsiliceous rocks in the Mesozoic In summary the siliceousrocks were mainly developed in tensional settings with apreferential distribution next to the suture zones
42 Major and Trace Elements Geochemical information(eg major- trace- and rare earth element data) of the anal-ysed siliceous rocks from the Bafangshan-Erlihe ore depositas well as the data from [1] used to examine their sedimentarydepositional environment genesis and geological context issummarized below
(1) The major elemental analysis results and geochemicalindices for the siliceous rocks are listed in Tables 1 and 2 Thegeochemical characteristics of major elements indicated thefollowing
(a) A hydrothermal genesis of the siliceous rocks issuggested according to themajor element characteristics withtheir formation process influenced by biological activitiesThe SiO
2content of the siliceous rocks ranges from 7108
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
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[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
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[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 9
Table2Major
elem
entsandrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
SiA
lMnO
TiO
2K 2
ON
a 2O
SiO
2(K
2O+N
2O)
SiO
2Al 2O
3Fe
2O3FeO
SiO
2MgO
Al(Fe
+Al
+Mn)
Al(Al+
Fe)
Al 2O
3(A
l 2O3
+Fe
2O3)
FeTi
(Fe+
Mn)Ti
Al 2O
3TiO
2
FE001
11560
4598
538
85639
13114
018
8114
022
023
074
97208
103145
32494
FE002
3485
096
1962
1491
03954
011
11579
058
059
096
2209
2332
3654
FE003
12568
717
862
6490
314258
009
5523
013
013
072
25088
26014
4264
FE00
43402
172
1962
12638
3860
007
3994
024
024
088
7829
8051
2863
FE005
35465
7852
877
135798
40234
012
3366
003
003
028
350366
360504
11271
FE00
61183
048
2363
4451
1342
021
5535
056
057
092
1698
1760
2542
FE007
4240
143
2059
17490
4811
022
7089
027
027
075
7013
7198
2958
FE008
8537
259
064
3873
89685
005
34653
033
035
094
3548
3883
2185
FB001
2522
143
2125
9258
2861
008
2861
045
046
094
4337
4521
4114
FB002
1791
133
1557
7006
2032
217
7667
034
034
051
7567
7740
4444
FB003
6226
400
1600
25553
7063
007
7363
024
025
088
1072
911245
4100
FB00
43694
025
825
12005
4191
135
1776
8057
058
077
1726
1758
2650
FB005
1866
038
1543
7123
2117
133
6159
039
039
061
4052
4102
2977
FB00
63774
200
1133
12438
4281
021
8145
042
043
086
6400
6659
5375
Aver
5427
528
1381
2696
76156
044
13670
036
037
082
13205
13887
5620
lowastlowastSamples
FB001toFB
006fro
mliterature[1]
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
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The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
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2multiple
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[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
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[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
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[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
10 The Scientific World Journal
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(a)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(b)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(c)
Central orogenic beltPrimary tectonic suture zoneSecondary tectonic suture zoneAltun Tagh fault zone
Boundary of EQL and WQLSiliceous rockCityProvincial boundary
Gansu
N
Qinghai
ShanxiHenan
Anhui
Wuhan
XianLanzhou
HanzhongHefei
EKL
NQ
WQLEQL
SL
M-SQ
DBYZB
NCC (SKC)
0 300(km)
Beijing
Chengdu
UrumqiHarbin
YZ
NCC (SK)TA
CT
1000 km
N34∘
E108∘
(d)
Figure 8 Distribution of siliceous rocks in central orogenic belt of China ((a) Precambrian (b) Eopaleozoic (c) Neopaleozoic (d)Mesozoic EKL eastern Kunlun M-SQ Middle-South Qilian NQ North Qilian WQL Western Qinling EQL Eastern Qinling SKC Sino-Korean craton YZB Yangtze block DB Dabie orogenic belt Data sources [32 37ndash40])
to 9530 with an average of 8410 The SiAl ratios rangebetween 1183 and 12568 which are lower than that of puresiliceous rock with ratios usually in the range from 80 to1400 [46] The Al(Al + Fe + Mn) ratios range from 003 to058 which are consistent with that of typical hydrothermalsiliceous rock of below 04 [47] Taking into account thatMgO is depleted in modern ocean ridges and was zero inthe hydrothermal water at 350∘C from the East Pacific [48]the MgO content of the analysed siliceous rocks (015 to288 ) is higher than that of pure hydrothermal siliceousrocks In addition the (Fe + Mn)Ti ratios of the siliceousrock varies from 1559 to 103145 which is consistent withthat of typical hydrothermal sediments (higher than 20 plusmn 5[49]) The Fe
2O3FeO ratios range from 001 to 217 and are
lower than that of the siliceous rocks of hydrothermal genesis
(typically 051 [50]) These characteristics as well as the asso-ciated geochemical discrimination diagrams of Al
2O3-SiO2
(Figure 9(a)) and Mn-Al-Fe (Figure 9(b)) strongly supporttheir genesis by hydrothermal sedimentation Moreover thesiliceous rocks plotted in the Fe
2O3FeO-SiO
2Al2O3and
SiO2(K2O + Na
2O)-MnOTiO
2diagrams indicated biologi-
cal influences during their formation processes (Figures 9(c)and 9(d))
(b) The siliceous rocks of the Bafangshan-Erlihe oredeposit were formed in a marginal sea basin According to[54] the Al(A1 + Fe + Mn) ratios of siliceous rocks arediverse depending upon sedimentary processes and theydecrease from 0619 in the continental margin to 0319 inoceanic basins or islands with a lower value 000819 atthe mid-ocean ridge This gradual reduction showed the
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 11
Non hydrotherm
al sed
imentat
ion
Hyd
roth
erm
al se
dim
enta
tion
Deep sea sedimentation
0 4 8 120
20
40
60
80
100
16 20
I
III
II
SiO2
()
Al2O3 ()
(a)
Mn
Al
FeHydrothermal sedimentary siliceous rocks
Biologically depositedsiliceous rocks
I
II
(b)
0 1 2 3 4 50
100
200
300
Biologically depositedsiliceous rocks
Hydrothermal sedimentarysiliceous rocks
I
II
SiO2
Al 2
O3
Fe2O3FeO
(c)
00
2
4
6
8
Hydrothermal sedimentarysiliceous rocks
Biologically depositedsiliceous rocks
I
II
200 400 600SiO2(K2O + Na2O)
MnO
TiO
2
(d)
Figure 9 Major element discrimination diagrams supporting hydrothermal and biological processes for the genesis of siliceous rocks of theBafangshan-Erlihe area (After (a)mdash[51] (b)mdash[52] (c) (d)mdash[53])
progressive influences of hydrothermal precipitation TheAl(Al + Fe + Mn) ratios of the studied siliceous rocks rangefrom 003 to 059 which are approximately equal to that ofsiliceous rocks from ocean basins or continental marginsThe contents of terrigenous Al and Ti are higher at thecontinental margin and they decrease with distance fromthe marginal sea The MnOTiO
2ratios range from 025 to
4598 which is higher than that of typical samples at thecontinental margin with ratios below 05 at the continentalmargin [52] In addition the Al(Al + Fe) ratios range from
003 to 059 which is lower than that of the bedded siliceousrocks along the continental margin [48] The Al
2O3(Al2O3
+ Fe2O3) ratios range from 051 to 096 which is close to
that of typical siliceous rock from marginal seas [53] Theabove characteristics agreewith the associated discriminationdiagram (Figure 10)
(c) There was no obvious volcanic activity during theprecipitation of hydrothermal silicaTheK
2ONa2Oratios for
the analysed siliceous rocks range from 064 to 2363 whichis much higher than that of the siliceous rocks deposited
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
12 The Scientific World Journal
01
10
100
1000
Mid ocean ridge
Marginal sea
Pelagic region
02 04 06 08 10
Fe2O3T
iO2
Al2O3(Al2O3 + Fe2O3)
Figure 10 Fe2O3TiO2versus Al
2O3(Al2O3+ Fe2O3) discrimina-
tion diagram indicating the formation environment of the siliceousrocks of the Bafangshan-Erlihe area (After [53])
by submarine volcanism [48] The SiO2(K2O + Na
2O)
ratios of the siliceous rocks ranged from 4451 to 85639which is much higher than that of the siliceous rocks fromchemical deposition related to volcanic eruptions [55] TheSiO2Al2O3ratios and the SiO
2MgO ratios range from 1342
to 14258 and from 2861 to 64933 respectively which ismuchhigher than that of siliceous rock related to magmatism withSiO2Al2O3lt 137 [14] The SiO
2MgO ratios range from
2861 to 64933 which is much higher than that of typicalsiliceous rocks related to magmatism [14] Despite the factthat there was no obvious volcanic activity during theirformation process some analysed siliceous rocks plot in thecategory related to volcanism (in Figure 11)Thismay indicatea magmatic contribution related to the deep faults
(2) The analytical results of trace elements are listed inTable 3 Trace element geochemistry indicates the following
(a) The siliceous rocks were originated from hydrother-mal precipitationThe Ba content of the siliceous rock rangesfrom 4245 ppm to 50300 ppmwith an average of 19664 ppmand is between that of the MORB (1200 ppm [57 58])and the crustal rocks (707 ppm [59]) The U ranges from007 ppm to 153 ppm with an average of 048 ppm whichis also between that of the MORB (010 ppm [57 58]) andthe crustal rocks (130 ppm [59]) These values are similarto those of hydrothermal sedimentary siliceous rocks andcontrast from those from terrestrial sediment [60]The UThratios range from 007 to 491 which is slightly lower thanthat of hydrothermal sediments [61] The BaSr ratios rangefrom 014 to 2597 which is in accordance with that ofhydrothermal siliceous rocks (BaSr gt 1 [62]) Additionally ahydrothermal genesis of the siliceous rocks is supported from
Biologically depositedsiliceous rocks
Volcanogenicsiliceous rock
105
105
104
104
103
103102
102 106
Al2O3 (times10minus6)
Na 2
O +
K2O
(times10
minus6)
Figure 11Major element discrimination diagram indicating biolog-ical and volcanic processes for the genesis of the Bafangshan-Erlihearea (After-[56])
Non hydrothermalsedimentation
Hydrothermal sedimentation MnFe
I
II
(Cu + Co + Ni) times 10
Figure 12 Trace element discrimination diagram indicating mostlyhydrothermal genesis for siliceous rocks from the Bafangshan-Erlihe area (After-[63])
the discrimination diagram of Mn-(Cu + Co + Ni) times 10-Fe(Figure 12)
(b) The siliceous rocks were deposited in a continentalabyssal environment The ScTh ratios of the siliceous rocksrange from 010 to 1385 which agree well with that of thesiliceous rocks formed in the continental margin [61] TheUTh ratios range from 007 to 491 which denote a deposi-tional environment that was remote from the mainland [61]TheV(V +Ni) ratios range from 009 to 072 which suggeststhat the deposition occurred in an oxygen-rich environmentwith V(V +Ni) lt 046 [64]The SrBa ratios range from 004to 695 with an average of 095 which indicate an abyssal seaor stagnant shallow sea [65] In the discrimination diagram
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
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[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
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[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
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[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
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[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
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[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
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[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
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[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
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[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
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[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
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[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
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[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 13
Table3Tracee
lementanalysis
result(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
NO
ScTi
VCr
Mn
Co
Ni
CuZn
Ga
Ge
RbSr
ZrNb
CsBa
Hf
TaPb
ThU
YTiV
VY
UTh
ScTh
V(V
+Ni)
VC
rNiC
oSrBa
FE001
108
2668
336
526
42330
098
357
1109
4493
042
194
221
1614
014
0009
101
21400
003
000
1467
093
007
792
793
042
007
116
049
064
363
075
FE002
094
29300
1207
1276
17230
2176
2901
361
4873
0407
1423
1640
1782
2463
155
118
12680
020
007
163520
099
021
082
2428
1479
021
094
029
095
133
014
FE003
008
9310
381
1546
74810
196
848
784
6658
045
607
450
6167
2625
109
071
21420
011
003
2545
030
011
186
2442
205
036
025
031
025
432
029
FE00
416
04312
01538
1703
39850
1753
2435
11140
775760
349
1428
2418
2962
379
039
073
3190
0053
011
103520
143
153
220
2804
699
107
112
039
090
139
009
FE005
166
1014
01216
1095
121900
318
475
14030
42680
206
318
1153
12410
1345
300
018
4245
008
002
195340
012
017
1009
834
121
143
1385
072
111
150
292
FE00
6005
5972
890
896
20340
129
1270
476
1243
030
004
209
35600
1058
080
064
5123
006
001
4870
024
120
340
671
262
491
020
041
099
987
695
FE007
091
26020
1071
1136
49600
1729
1668
1576
0316540
184
817
1333
3300
314
019
021
8051
026
006
88590
095
042
187
2430
574
044
096
039
094
096
041
FE008
104
60090
1383
1524
34550
292
996
4518
12490
228
064
462
7208
1570
141
117
33050
025
013
4873
053
019
403
4345
344
037
197
058
091
341
022
FE00
9015
11010
777
2034
17030
505
880
37640
mdash313
729
712
1063
1337
090
080
2478
0016
003
986580
082
096
049
1417
1576
117
018
047
038
174
004
FE010
147
31270
1305
2367
4894
04348
4874
769100
2210
015
1520
1283
3596
708
036
042
7060
064
009
mdash14
1021
261
2396
500
015
104
021
055
112
051
FE011
114
4113
01370
1668
1473
014320
14530
2099
021410
291
1228
2352
1036
1207
054
026
1596
0029
009
42310
137
032
112
3002
1220
023
083
009
082
101
006
FE012
004
11300
682
2436
2177
0355
1001
3274
113410
125
817
661
1937
1012
100
239
50300
021
003
23550
042
039
081
1658
837
093
010
041
028
282
004
Aver
085
23444
1013
1517
4192
32185
2686
72365
124138
197
679
1075
7767
1180
094
081
19664
023
006
147015
079
048
310
2102
655
097
188
040
073
276
104
lowastmdashoutwith
detectionlim
itsof
theinstrum
ent
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
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[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
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[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
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[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
14 The Scientific World Journal
00
20
40
60
80
Mid ocean ridge
Marginal sea
Ocean basin
1000 2000 3000
V (times
10minus6)
Ti (times10minus6)
Figure 13 Trace element discrimination diagram demonstratingformation environment at a marginal sea basin for the siliceousrocks of the Bafangshan-Erlihe area (After-[46])
of Ti-V the siliceous rocks plot into the category of marginalsea (Figure 13)
(c)There was slight influence from themaficmagmatismAccording to [64] the VCr gt 2 and NiCo gt 4 reflectan anoxic depositional environment while the VCr lt 2and NiCo lt 4 indicates an oxygen-rich depositional envi-ronment The VCr ratios of the analysed siliceous rocksrange from 025 to 111 which indicate that the depositionalenvironment was oxygen-rich The NiCo ratios range from096 to 987 which indicate either an oxygen-rich deposi-tional environment or a participation of mafic magmatism[64] The presence of mafic magmatic activity could alsocontribute to the high Cr content in the siliceous rocks [66]According to the ScTh UTh and SrBa ratios the VCr andNiCo ratios were probably influenced by the mafic magmarather than an aerobic environmentThe associatedmagmaticactivity should be related to the deep faults such as Fengxian-Fengzhen-Shanyang and Jiudianliang-Zhenan-Banyan faults[1 32 34] Although there was no volcanic activity during thedeposition process (Figure 11) the deep faults in the Fengtaiarea could also have provided favorable conditions for themafic magmatism to affect hydrothermal convection
(3) The analytical results of the rare earth element areshown in Table 4 and they indicated the following
(a)The siliceous rocks originated fromhydrothermal pre-cipitation with slight influences from terrigenous materialsThe ΣREE values of the siliceous rocks range from 328 ppmto 1975 ppm with an average of 983 ppm which is consistentwith that of siliceous rocks of hydrothermal sedimentarygenesis [67] Normalized by the PAAS [44] (Figures 14(a)and 14(b)) the siliceous rocks are divided into two groupsOne group is tilted to the left with positive Eu anomalies andslightly weak Ce negative anomalies (Figure 14(a)) which is
consistent with those of siliceous rocks with hydrothermalgenesis The other group is similar to that of the non-hydrothermal siliceous rock with negative Eu anomalies(Figure 14(b)) but does not support the nonhydrothermalgenesis because of their inclination to the left Because theocean basin was insufficiently wide to prevent the terrestrialmaterials from influencing the original sedimentation pro-cess the REE were only slightly affected by the terrestrialinput with negative Eu anomalies (Figure 14(b))
(b) The siliceous rocks were deposited in a marginal seabasin The (LaYb)
119873ratios of the analysed siliceous rocks
range from 010 to 152 similarly to that of siliceous rockdeposited in the basin of the marginal sea [68] The 120575Cevalues of siliceous rocks are typically 029 at the mid-oceanridge increasing gradually to 055 in the ocean basin andrange from 090 to 130 in the marginal sea next to thecontinent [68 69] In this study the present 120575Ce values (from080 to 092) are consistent with those of siliceous rocksdeposited in the basin of a marginal sea [69] The (LaCe)
119873
ratios of siliceous rocks are typically 1 when deposited inmarginal seas [53] which reflect the influences of terrigenousinput [70]The (LaCe)
119873ratios of the analysed samples range
from 085 to 146 which coincides with that of siliceous rockfrom marginal seas [53] Also the (LaLu)
119873ratios (from 013
to 137) from the analysed siliceous rocks are approximatelyequal to that of siliceous rock deposited in marginal seas[67] The hydrothermal diagenesis is represented by a Eu-positive anomaly [71] whose 120575Eu value generally decreasesfrom 135 at the mid-ocean ridge to 102 at 75 km from themid-ocean ridge [53 67] The 120575Eu values (from 028 to 184)of the analysed rocks did not match that of the siliceous rockformed at the mid-ocean ridge [69] In the Al
2O3(Al2O3
+ Fe2O3)-(LaCe)
119873discrimination diagram (Figure 15) the
siliceous rocks plot in and next to the marginal sea field
43 Raman Spectroscopy Raman analysis was performed onthe points (A rarr G) as shown in the microphotographs ofFigures 16(a) and 16(b) The micrographs illustrate deformedquartz grains and carbonate minerals The ellipses in Figures16(a) and 16(b) represent the straining ellipse for granularquartz formation which was analysed in parallel (A B andE) and oblique crossing (C to G) directions in relation to themacroaxis In the Raman analysis the points were analysed insitu in certain directions (the direction in parallel with pointsA B and E while the oblique crossing direction includingpoints C D E F and G) The spectral configurations forall the points are discussed elsewhere [15] As shown in thespectrogram of the analysis points (ArarrG) (Figure 16(c))the peaks are mainly caused by the SindashO bond of quartzand the CO
3
2minus ion of carbonate mineral In Figure 16(c) thepeaks at 464 cmminus1 exhibit 120572-quartz according to previouswork [72] and they were treated as a characteristic Ramanshift In addition the peaks at 1112 cmminus1 were also controlledby the SindashO bond according to previous studies [73ndash75]There are remarkable scattering peaks at 1091 cmminus1 andthey fall into the overlapping range of the antisymmetricvibration peak (from 1010 cmminus1 to 1125 cmminus1) of SindashO and theR vibration peak of the V-band for CO
3
2minus (from 1050 cmminus1
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
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[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
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[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
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[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 15
Table4RE
Eanalysisresults
(times10minus6 )andrelated
geochemicalindicesfor
siliceous
rocksfrom
theB
afangshan-Erlih
earea
No
LaCe
PrNd
SmEu
Gd
TbDy
YHo
ErTm
YbLusumRE
E120575Ce120575Eu
(LaCe)119873
(LaYb
) 119873(LaLu
) 119873FE
001
309
646
086
349
086
038
112
023
136
792
027
075
011
068
010
1975
092
184
100
033
037
FE002
225
320
030
089
015
002
015
002
015
082
003
010
002
013
002
743
090
072
146
133
127
FE003
062
136
019
092
026
007
026
005
033
186
006
018
003
019
003
455
091
128
095
024
027
FE00
4339
553
059
194
032
005
032
006
038
220
009
025
004
029
005
1329
090
068
128
086
083
FE005
091
222
037
194
078
021
112
025
159
1009
034
088
012
065
008
1145
088
105
085
010
013
FE00
618
8321
040
161
033
006
035
006
036
340
007
019
003
017
002
872
085
077
122
084
101
FE007
181
301
034
127
029
002
028
006
033
187
007
021
004
025
004
802
089
028
125
053
050
FE008
224
458
060
249
056
019
058
010
058
403
012
037
006
041
006
1293
091
158
102
041
040
FE00
9072
137
018
082
017
002
016
002
009
049
002
004
001
004
001
366
087
063
110
144
136
FE010
285
474
053
202
048
005
046
008
050
261
011
035
005
039
007
1266
089
047
125
054
047
FE011
351
553
054
160
020
001
019
003
017
112
004
014
002
017
003
1217
093
015
132
152
137
FE012
070
124
014
057
013
002
013
002
012
081
003
008
001
009
002
328
091
060
117
055
053
Aver
200
354
042
163
038
009
043
008
050
310
010
029
004
029
004
983
090
084
116
072
071
ndash119873representn
ormalized
byPA
AS[44]120575Ceand120575Cec
omefrom
[45]120575Ce=
CeCelowast
=Ce 119873
(La119873timesPr119873)1
2and120575Eu
=Eu
Eulowast
=Eu119873(Sm119873timesGd 119873
)12
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
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[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
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The Scientific World Journal 23
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[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
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[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
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[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
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[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
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[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
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[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
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[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
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[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
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[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
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[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
16 The Scientific World Journal
Sam
ple
PAA
S
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
10
1
10minus1
10minus2
10minus3
10minus4
(a)
La Pr Eu Tb Y Er Yb
(Pm
)
Ce
Nd
Sm Gd
Dy
Ho
Tm Lu
Sam
ple
PAA
S
10
1
10minus1
10minus2
10minus3
10minus4
(b)
Figure 14 PAAS normalized REE pattern for siliceous rocks from the Bafangshan-Erlihe area
0 02 040
1
2
3
4
Mid ocean ridge
Marginal sea
Deep sea
06 08 1Al2O3(Al2O3 + Fe2O3)
(La
Ce)
N
Figure 15 Al2O3(Al2O3+ Fe2O3) minus (LaCe)
119873discrimination
diagram for siliceous rock of the Bafangshan-Erlihe area (After-[53])
to 1090 cmminus1) According to the Raman shift of calcite [76]and other carbonate minerals [77] the peaks at 1091 cmminus1should be attributed by the vibration of the V
1-zone for the
carbonate ions (CO3
2minus) Additionally the peaks at 1091 cmminus1are in accordance with the weak peak of the V
4-zone at
722 cmminus1 for carbonate ions which are similar to peaks ofankerite In the spectrograms two weak peaks at 840 cmminus1and 1186 cmminus1 could have originated from the metamorphicreaction between silica and carbonate which exhibit sym-metric and antisymmetric stretching vibration peaks for SindashOndashR and they are too weak to accurately estimate The
peaks at 1608 cmminus1 which are attributed to the CndashC bondin benzene rings came from the organic gum used in theexperiment The weak peaks at 280 cmminus1 falling into therange of silicate mineral scattering peaks [78 79] could havearisen from the metamorphic reaction between silica andcarbonate There are peaks on curves C to G for both quartzand carbonate minerals in the spectrogram (Figure 16(c))This phenomenon demonstrates the carbonate compositioninfiltrating the quartz through the discontinuous portioncaused by stress during orogeny In addition the degree ofinfiltration increases from the edge to the centre of the quartzgrain [15]
The crystallinity and degree of order for the quartz grainsincreased during recrystallization [80 81] which could bedenoted by the Gaussian best-fit to the characteristic Ramanpeaks at 464 cmminus1 for the quartz grains [82 83] Figure 17suggests a Gaussian fitting for the characteristic Raman shiftsat 464 cmminus1 from points C to G In the Gaussian fitting thefull width at half maximum (FWHM) values ascends fromthe centre outwards in concert with the crystallinity anddegree of order but abruptly descends at the edge closest tothe carbonate periphery According to previous work [80]the crystallinity increases during the upper evolution of thequartz minerals from the centre to the quartz edge Basedon this finding the FWHM values ascend from the centreoutwards meaning that the decline in crystallinity mightbe a result of the autorecrystallisation of quartz The abruptincrease in crystallinity exists at the edge of quartz and thisshould be contributed by the fluids during orogeny
According to Figure 18 the Gaussian fitting of character-istic Raman shifts at 464 cmminus1 indicates discrepancies in adirection parallel to themacroaxis In Figure 16(b) the pointsof A B and E lay parallel to the macroaxis of the quartzgrains and their FWHM values also showed some slightdiscrepancies According to the discrepancy in the FWHMvalue there are slight deviations of crystallinity parallel to themacroaxis of the straining ellipse These deviations should
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 17
FG
20120583m
(a)
A
B
CDE
20120583m
(b)
Inte
nsity
(au
)
200
1608
1186
11121091
840
722
464
280
(G)(F)
(E)(D)
(C)(B)(A)
400 600 800 1000 1200 1400 1600 1800Raman shift (cmminus1)
(c)
Figure 16 Points of Raman analysis for siliceous rocks of Bafangshan-Erlihe areaMicrophotographs in Figures 16(a) and 16(b) under parallelnicols
450
1800
2000
2200
2400
2600
2800
3000
3200
3400
70727476788082
Inte
nsity
(au
)
Points
455 460 465 470 475 480 485
G-FWHM= 709F-FWHM = 793E-FWHM = 707D-FWHM = 721C-FWHM = 708
FWH
M(c
mminus1)
C D E F G
Raman shift (cmminus1)
Figure 17 Gaussian fitting to characteristic Raman shift of quartzin siliceous rock from Bafangshan-Erlihe area
relate to external factors during orogeny such as the stressfield and fluid effectsTherefore there are overall geochemicalstabilities for the siliceous rocks with slight changes in thecrystallinity
44 XRD X-ray powder diffraction (Figures 19(a) and 19(b))of the pure siliceous rock indicates quartz as the majormineral Trace impurities such as carbonate and clay min-erals are concealed in the analytical results There are two
1200
1400
1600
1800
2000
2200
2400
66687072747678808284
Inte
nsity
(au
)
Points
A-FWHM = 761
B-FWHM = 720
E-FWHM = 707
FWH
M(c
mminus1)
A B E
450 455 460 465 470 475 480 485Raman shift (cmminus1)
Figure 18 Gaussian fitting to a characteristic Raman shift forsiliceous rock of the Bafangshan-Erlihe area
types of quartz in the siliceous rocks (Figure 19(b)) One(Qtz) is hexagonal with space group P3
121(152) the crystal
cell parameters of which were 119886 = 119887 = 4913 A 119888 =5405 A and 119885 = 3 that is identical to those of standard120572-quartz The other (Qtzs) is rhombohedral having shortercrystal cell parameters and is similar to a quartz with spacegroup P312(149) as noted elsewhere [15 18] The crystal cellparameters were 119886 = 119887 = 4903 A 119888 = 5393 A and 119885 = 3
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
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[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
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[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
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[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
18 The Scientific World Journal
20
0500
1000150020002500300035004000450050005500600065007000
Inte
nsity
(au
)
40 60 802120579 (∘)
2120579=2088d=425
2120579=2668d=334
2120579=3090d=289
2120579=3658d=245
2120579=3950d=228 2120579=4032d=224
2120579=4248d=213 2120579
=5535d=166
2120579=5998d=154
2120579=6404d=145
2120579=6776d=138
2120579=6832d=137
2120579=7350d=129
2120579=7569d=126
2120579=7770d=123
2120579=8148d=118
2120579=8384d=115
2120579=7592d=125
2120579=7992d=120
2120579=4584d=198
2120579=5016d=182
2120579=5491d=167
(a)In
tens
ity (a
u)
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
2
20 40 60 802120579 (∘)
QtzQtzs
n Overlap
(b)
Figure 19 XRD diagram for siliceous rock of the Bafangshan-Erlihe area
The crystal cell parameters should be similar under uni-form crystallizing environments and evolutionary processesAccording to previous work changes in crystal cell param-eters can be effected by four factors as follows temperature[84] stress [85] transformation into different crystal forms[86 87] and isomorphous substitution [88] In this studycrystal cell parameter shortening was possibly controlled bythe primary factors of temperature and stress during theevolution of the COB while the other factors could only havelengthened the cell parameters
45 SEM In the Electron Back Scatter Diffraction (EBSD)images of mineralized siliceous rock (Figure 20(a)) there arethree principal phases namely quartz carbonate mineral(calcite or dolomite) and metal sulphides (such as galenasphalerite or pyrite) The quartz particles of low crystallinityoccupy the main body of the siliceous rocks while thecarbonates and metal sulphides are scattered with dissemi-nated distribution (Figures 20(a) and 20(b)) The carbonateparticles (Figure 20(c)) and pyrite (Figure 20(d)) sometimesshow idiomorphic crystals which indicates that they wereoriginated from primary sedimentation Metal sulphideswere probably deposited at the end of high-temperaturesedimentation Although the siliceous rocks were involvedin subsequent orogeny (Figure 20(b)) the metal sulphidesare mainly disseminated without fracture-filling distribution(Figures 20(a) to 20(c)) Although the distribution of metalsulphides retained the primary characteristics of sedimentarygenesis a few metal sulphides with fracture-filling distribu-tion might have been affected by the orogeny These typesof metal sulphides are distributed near the weaker part ofthe siliceous rocks such as the fissures of the quartz and thecarbonate mineral (Figure 20(b)) Therefore it is suggestedthat the silica and metal sulphides were simultaneously
deposited and the metal sulphides are also precipitationproducts of hydrothermal sedimentation The dominantminerals show low automorphism which is attributed bytheir rapid deposition with insufficient time to crystallize andgrow
5 Discussion
51 Mineralogical and Geochemical Evolution The studiedsiliceous rocks underwent mineralogical adjustments withmaintenance of geochemical stability In nature elevatedtemperatures and pressures result in deformation of differentrocks [89] The quartz grains show plastic deformationunder the strain rate of 0sim10minus13s and temperature of 300∘C[90] Microscopically we observed recrystallized quartz withlarger grain size in the siliceous rocks withoutmineralizationwhich exhibits directional arrangement to some extent In theRaman analysis the FWHM values of characteristic peaks(next to 464 cmminus1) showed inhomogeneity in the degree ofcrystallinity in diverse directionsThis indicated that the crys-tallinity is different in the microareas of an individual quartzgrain As shown in the XRD analysis the recrystallizationof quartz was witnessed by the shortening cell parameterof quartz grains Thus the recrystallization of quartz isevidenced by both XRD analysis and Raman in situ analysisAlthough the quartz underwent clear recrystallisation underthe influences of temperature and stress during the orogeny(according to [91]) these changes could only account forfabric changes It is demonstrated that the degrees of orderin silica minerals may increase without exterior influence[76] and that geochemical stability of the total rocks canbe still maintained with increasing crystallinity degree [80]For the studied siliceous rocks there is a high consistency tothe hydrothermal genesis model based on the geochemical
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 19
Carb
Ms
150120583m
(a)
Carb
Ms
150120583m
(b)
Carb
50120583m
(c)
Pyr
30120583m
(d)
Figure 20 EBSD images for siliceous rock of the Bafangshan-Erlihe area (Carb carbonate mineral Ms metal sulphide Pyr pyrite)
and microfabric characteristics as well as the geochemicaldiscrimination diagrams of formation environment Ourstudy suggests that there is high stability for the originalgeochemical characteristics of the siliceous rocks and thatthese were maintained without any change in the total rocks
52 Genesis of Siliceous Rocks It is suggested here that thesiliceous rocks in Central Orogenic Belt China and theBafangshan-Erlihe ore districts are hydrothermal precipi-tates The siliceous rocks in addition to clay rock clastic andcarbonate rocks are the most widely distributed sedimentaryrock in this orogenic belt [3 19 92] and their formationis previously attributed to biogenesis [93] metasomatosis(or silicification) [94 95] or chemical deposition [49 96]On a large scale the sedimentary siliceous rocks couldhardly be deposited in the marine environment with onlyterrigenous silica contribution The high purity and largequantity of silica consumed for the deposition of the siliceousrocks could not be completely caused by any terrigenousand nonhydrothermal deposition system [97ndash99] This sup-ports the idea that the massive sedimentary siliceous rockswere originated from hydrothermal precipitation accordingto [100] The pure siliceous rocks could only have beendeposited if the silica was present at a higher concentration
in solution than other chemical components resulting inhigh deposition rates of silica and favouring deposition ofsiliceous rocks instead of other sediments (carbonate clayand metallic minerals) [16] In this way high rates of puresilica accumulation would develop without interference fromother sediments Terrigenous silica is difficult to precipitateduring themigration process because of its very low solubility[101] Even if there was rapid precipitation of silica at a lowconcentration it was still difficult to deposit the siliceoussediments at a large scale with high purity after long-termand sustained transportation or other extreme conditions[99] Furthermore the SiO
2was extremely low in the normal
seawater and this could contribute to a low deposition rate[16 97] while the quartz grains would grow better andbigger due to the adequate crystallizing time The quartzgrains in the siliceous rocks from the Bafangshan-Erlihe areaseem to have insufficient crystallization and growth whichis in contrast to quartz originated from the deposition ofterrigenous silica with a low deposition rate The micropho-tographs and EBSD indicate the silica minerals exhibitedlow-degree crystallinity which was in accordance with thetypical siliceous rocks of hydrothermal genesis [36] Duringthe hydrothermal precipitation the quartz grains could notfully crystallise at high deposition rates of silica and they
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
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[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
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[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
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[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
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[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
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rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
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2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
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[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
20 The Scientific World Journal
therefore showed close-packed structures as a consequenceof their rapid accumulation of the silica
The ore-bearing siliceous rocks of Bafangshan-Erlihe areawere considered to be of hydrothermal genesis also on thebase of their geochemical characteristics Some geochem-ical indices such as the average Ba (19664 ppm) ΣREEvalues (983 ppm) and ratios of Al(Al + Fe + Mn) (036)FeTi (33544) (Fe + Mn)Ti (34780) and BaSr (807)all suggest their genesis through hydrothermal depositionIn the geochemical discrimination diagrams the siliceousrocks fall into the category of hydrothermal genesis andthis is in agreement with their REE patterns Therefore itis considered that the siliceous rocks were deposited from aconvective hydrothermal system within a crustal extensionalsetting On the other hand the MgO ΣREE SiAl andUTh of several samples disagree with the hydrothermalcharacteristics and indicate that the sedimentary systemswere affected by the input of nonhydrothermalmaterials (egterrigenous and biological substances) The contribution ofterrigenousmaterials is strongly supported by the presence ofdetrital zircons in the siliceous rocks [12] Microorganismscarrying terrigenous substances were also involved in theprecipitation process of the hydrothermal silica and resultedin the observed fluctuations fromnormal hydrothermal char-acteristics Therefore the ore-bearing siliceous rocks in theBafangshan-Erlihe area were originated from hydrothermalprecipitation with some additional influence from terrige-nous and biological sources
53 Depositional Environment of Siliceous Rocks The sili-ceous rocks of the Bafangshan-Erlihe area were deposited ina limited basin of a marginal sea They were conformablydeposited over the Middle Devonian marine limestonewhich indicates their deposition in a marine environmentwith deep to shallower water The geochemical indicessuch as the Al(Al + Fe + Mn) Al
2O3(Al2O3+ Fe2O3)
ScTh (LaYb)119873 (LaCe)
119873 and (LaLu)
119873 demonstrate
that the siliceous rocks were deposited in a marginal seabasin in coincidance with the geochemical discrimina-tion diagrams The K
2ONa2O SiO
2(K2O + Na
2O) and
SiO2Al2O3ratios are significantly higher than those of
volcanism-related siliceous rocks and indicate that therewas no obvious volcanic activity during the formation pro-cess However magmatic bodies emplaced at depth andunder extensional conditionsmay have caused hydrothermalconvection through deep faults by providing heat in thesystem The associated magma was mafic according to theVCr and NiCo ratios The V(V + Ni) ratios indicate thatthe sedimentation conditions were slighlty oxidative whichshould reflect intermingling with terrigenous substances Inprevious studies [102ndash104] it has been suggested that theocean basin of the COB was width-limited and narrowwhich strongly supports the input of terrigenous materialsduring the hydrothermal precipitation In agreement with theprevious studies [102 104] a deposition of siliceous rocks inrelatively shallow seawater is also supported by the fact thatthese rocks are located on top of carbonate rocks ofGudaolingFormation According to the geochemical characteristics
NCYZ WQL
Basement of pre-devonian
Silica
MagmaConvective sea water
Pb-Zn-Cu sulfide silica
Tensional stressSea water
N
Terrigenous input
Middle devoniangudaoling formation
Sea water Sea water
Hydrothermal water withsulfides and (or) silica
Hydrothermal chimney
1205903
1205903
1205903
Figure 21 Hydrothermal precipitation model of the Bafangshan-Erlihe area (YZ Yangtze block WQL western Qinling block NCNorth China block)
and the presence of detrital zircons in the siliceous rocks[12] terrigenous materials participated in the sedimentationprocess of hydrothermal silica The hydrothermal activityattracted many elements with an affinity to silicon [105]and this attraction might induce the biological productionwithin a large population of organisms [106 107] Theseorganisms can carry nonhydrothermal substances because oftheir long-distance activities and needs for special elementssuch as phosphorus [108] Under this situation the organismswhich were involved in the sedimentation process exhibitalso terrigenous characteristics and their dead bodies andcatabolites have been deposited together with hydrothermalsediments according to [106] Both terrigenous material andbiological activities partly contributed to the formation ofthe siliceous rocks as may be expected to be the case ina geological setting of a limited ocean basin [102ndash104] Byexpanding previous studies that the COB was neritic faciesduring the Middle Permian [28] this work suggests that thewhole COB was a limited ocean basin with deep to shallowerseawater neritic facies since the Middle Paleozoic
54 Hydrothermal Model The hydrothermal sedimentationat the Bafangshan-Erlihe area was controlled by the exten-sional tectonic setting during Devonian times and under-went different stages with diverse contribution of hydrother-mal fluids (Figure 21) In general the entire process ofhydrothermal activity experienced an evolution from high-temperature precipitation of sulphide to low-temperatureprecipitation of silica (see below)Within the broad spectrumof exhalative-inhalative deposits the two end-members forexample sedimentary exhalative deposit (SEDEX) [109 110]and volcanogenic massive sulphide deposit (VMS) [111 112]are diverse in respect to their country rocks and ore-hosting rocks as well as their fluid origin and characteris-tics According to published literatures [113 114] sulphide-bearing hydrothermal solution exhaled at the initial stagesof hydrothermal activity under high temperatures followedby exhalation of the silica-enriched hydrothermal waters ata lower temperature with low dissolving capacity Therefore
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
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[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
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[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
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[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
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[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 21
the silica rich hydrothermal water and sulphide-bearinghydrothermal solutions belonged to part of an evolvinghydrothermal system Previous studies delineate two modelsfor the formation of SEDEX deposits one considers tec-tonic activity and the geothermal gradient during sedimentcompaction (diagenesis) as the key factors for ore elementmigration in a highly saline formational brine while theother considers hydrothermal fluids generated from seawaterconvection driven by a magma chamber intruding intosediments and synsedimentary fault activity as key factors inmineralization [115ndash118] According to the VCr and NiCoratios and discrimination diagrams the siliceous rocks aswell as the metal sulphides of the Bafangshan-Erlihe oredeposit were originated from the convection of hydrother-mal water Similarly other trace elements could have beenintroduced from the hydrothermal water to form ore deposits(according to [8 9]) In the Bafangshan-Erlihe region the seabasin was formed as a result of the extensional tectonics (egrifting) Normal basin-bounding faults related to the exten-sional tectonic setting near the suture zones could facilitateemplacement of magmas as proposed by [16] The exten-sional tectonics could also provide a favorite environment todrive the hydrothermal convection [43] The hydrothermalwater moved upward along the syn-sedimentary fracturesin the Bafangshan-Erlihe area precipitating hydrothermalsediments on the seafloor within the basin after mixing withcold seawater
During the final stages of magmatic activity high tem-perature hydrothermal water with high potential solubilityand dissolution of silica were analogous to those precip-itating modern metal sulphide chimneys (black smokers)[119] In the ores from the Bafangshan-Erlihe Cu-Pb-Zn oredeposit [120] the isotopic 206Pb204Pb (from 1802 to 1815)207Pb204Pb (from 1556 to 1581) and 208Pb204Pb (from 3799to 3866) are similar to those of modern oceanic sedimentswhich suggest their sources from both the upper crust andmantle In addition the 12057534S values of sulphides range from603permil to 1186permil and indicate a genesis of sulphides bysulphate reduction from seawaterThese isotope geochemicalcharacteristics strongly support the hypothesis that the oreswere deposited in a marine context during hydrothermalconvection as also evidenced by the distribution of metalsulphides in the ore-bearing siliceous rocks Furthermore theorebodies were located at the bottom of the siliceous rockswhich suggests that their precipitation predates that of silicaand took place at the onset of the hydrothermal activity athigher temperatures
A decrease in silica solubility at lower temperaturesresulted in precipitation of pure silica Since the solubilityof silica is higher than that of metal sulphides at lowtemperatures [113] pure silica could only deposit at a relativelow temperature At this time the hydrothermal precipi-tation process was akin to that of colder silica-enrichedhydrothermal water (white chimney) [114] Previous studiesdemonstrated that SiO
2solubility in the seawater at 150∘Cwas
600 ppm [100] while it was ten times higher at 200∘C than50∘C [121] Therefore the hydrothermal fluid was capable todissolve silica and other trace elements from the sedimentary
strata and became silica-enriched By discharging on theseafloor the silica-rich hydrothermal fluid mixed with thecold seawater and the temperature dropped to cause silicaprecipitation as a consequence of SiO
2oversaturation [122]
The hydrothermal- and tectonic activities were con-temporaneous at the Bafangshan-Erlihe area Following thehydrothermal activity deposition of the clastic rock forma-tion (later metamorphosed to phyllites) and limestones tookplace The hydrothermal system contributed to the precipita-tions of metal sulphide and siliceous rocks with geochemicalcharacteristics of hydrothermal genesis Terrigenous mate-rial magmatism and biological activity resulted in somegeochemical deviation compared with classic hydrothermalsediments but without changing the hydrothermal charac-teristics of the whole sedimentary formation
6 Conclusions
(1) Siliceous rocks of the Bafangshan-Erlihe ore deposit wereoriginated from hydrothermal precipitation In micropho-tographs andEBSD images the lowdegree of crystallinity andclose-packed quartz grain texture indicates their hydrother-mal genesis The SiO
2content varies from 7108 to 9530
with an average of 8410 The hydrothermal genesis of thesiliceous rocks is witnessed by the Al(Al + Fe + Mn) ratioranging from 003 to 058 (Fe +Mn)Ti ranging from 1559 to103145 Ba ranging from 4245 ppm to 50300 ppm and ΣREEvalues ranging from 328 ppm to 1975 ppm
(2) Siliceous rocks of the Bafangshan-Erlihe region weredeposited in marginal sea basin according to the geochem-ical discrimination diagrams Additional geochemical dataindicating that the deposition environment was a basin ofa marginal sea are Al(Al + Fe + Mn) ratios ranging from003 to 058 ScTh ratios ranging from 010 to 1385 (LaYb)
119873
ratios ranging from 010 to 152 (LaCe)119873ratios ranging from
085 to 146 and (LaLu)119873ratios ranging from 013 to 137
(3) The siliceous rocks in the Central Orogenic BeltChina had a periodic distribution in geological history andwere mainly developed under periods of continental riftingThere were three depositing phases for the marine siliceousrocks with broader distribution from Mesoproterozoic toJurassic The periods for the positive peaks of distributionnumber were Mesoproterozoic Cambrian simOrdovician andCarboniferous sim Permian During the Caledonian (fromSimian to Late Silurian) and Hercynian (from Devonianto Late Permian) periods the siliceous rocks are widelydistributed as a result of extentional tectonics favoring theirformation The Jinning Caledonian Hercynian Indosinianand Yanshanian orogenies contributed to compressionalsetting and resulted in a sudden decrease in distributionnumbers of siliceous rock
(4) Hydrothermal fluids ascended along syn-sedimentaryfaults in the Bafangshan-Erlihe area discharging hydrother-mal sediments on the seafloor after mixing with cold seawa-ter The hydrothermal activity of the Bafangshan-Erlihe oredeposit evolved from initial high-temperature towards latelow-temperature stages High-temperatured hydrothermalsediments include metal sulphides and silica while low-temperature sediments were mainly composed of silica
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
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[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
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The Scientific World Journal 23
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[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
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[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
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[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
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[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
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[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
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[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
22 The Scientific World Journal
Apart from the hydrothermal sedimentation terrigenousinput magmatism and biological activity partly contributedto some geochemical indicators deviating from typicalhydrothermal characteristics
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This study was financially supported by the Natural ScienceFoundation of China (Grant 41303025) the 973 Programof China (Grant 2012CB406601) the Natural Science Foun-dation of China (Grants 41373025 and 41273040) and theSubject and Special Fund of theMinistry of Science andTech-nology of the State Key Laboratory of Geological Processesand Mineral Resources (Grant GPMR200804) Professor GRacki Y Watanabe and Professor M Santosh are greatlyacknowledged for their helpful and constructive commentson the manuscript Professor G Racki is especially thankedfor the editorial handling of the paper
References
[1] W Fang F Liu R Hu and Z Huang ldquoThe characteristics anddiagenetic-metalogenic pattern for cherts and siliceous fer-rodolomitites from Fengtai apart-pull basin Qinling orogenrdquoActa Petrologica Sinica vol 16 no 4 pp 700ndash710 2000
[2] S Feng H Zhou C Yan Y Peng X Yuan and J He ldquoGeo-chemical characteristics of hydrothermal cherts of erlangpinggroup in east qinling and their geologic significancerdquo ActaSedmentological Sinica vol 25 no 4 pp 564ndash573 2007
[3] C Zhang D Zhou G Lu J Wang and RWang ldquoGeochemicalcharacteristics and sedimentary environments of cherts fromKumishi ophiolitic melange in southern Tianshanrdquo Acta Petro-logica Sinica vol 22 no 1 pp 57ndash64 2006
[4] H Li Y Zhou Z Yang et al ldquoGeochemical characteristics andtheir geological implications of cherts from Bafangshan-Erlihearea in Western Qinling Orogenrdquo Acta Petrologica Sinica vol25 no 11 pp 3094ndash3102 2009
[5] G Tu Geochemistry of the Stratabound Ore Deposits in Chinavol 1 Science Beijing China 1984
[6] J Mao Z Zhang J Yang G Zuo and D Ye The Metallo-genic Series and Prospecting Assessment of Copper Gold Ironand Tungsten Polymetallic ore Deposits in the West Sector ofthe Northern Qilian Mountains Geological Publishing HouseBeijing China 2003
[7] D Fan T Zhang and J Ye Chinese Black Rock Series and Rel-evant Ore Deposits Science Publishing House Beijing China2004
[8] N Tribovillard T J Algeo T Lyons and A Riboulleau ldquoTracemetals as paleoredox and paleoproductivity proxies an updaterdquoChemical Geology vol 232 no 1-2 pp 12ndash32 2006
[9] S E Calvert and T F Pedersen ldquoChapter fourteen elementalproxies for palaeoclimatic and palaeoceanographic variabilityin marine sediments interpretation and applicationrdquo Develop-ments in Marine Geology vol 1 pp 567ndash644 2007
[10] S Qi ldquoDevonian hydrothermal sedimentary Pb-Zn deposits inQinling mountainsrdquo Journal of Changan University vol 15 no1 pp 27ndash34 1993
[11] S Qi and Y Li ldquoThe metallogenic series related to exhalativesedimentation in devonian metallogenic belt south QinlingrdquoJournal of Xirsquoan College of Geology vol 19 no 3 pp 19ndash26 1997
[12] R T Wang F L Li E H Chen J Z Dai C A Wang and X FXu ldquoGeochemical characteristics and prospecting prediction ofthe Bafangshan-Erlihe large lead-zinc ore deposit Feng CountyShaanxi Province Chinardquo Acta Petrologica Sinica vol 27 no 3pp 779ndash793 2011
[13] C Xue J Ji L Zhang D Lu H Liu and Q Li ldquoThe Jingtieshansubmarine exhalative-sedimentary iron-copper deposit inNorth Qilian mountainrdquo Mineral Deposits vol 16 no 1 pp21ndash30 1997
[14] F Zhang ldquoThe recognition and exploration significance ofexhalites related to Pb-Zn mineralizations in devonian forma-tions in qinling mountainsrdquo Geology and Prospecting vol 25no 5 pp 11ndash18 1989
[15] H Li Z Yang Y Zhou et al ldquoMicrofabric characteristics ofcherts of Bafangshan-Erlihe Pb-Zn ore field in the westernQinling orogenrdquo Earth Science vol 34 no 2 pp 299ndash306 2009
[16] H Li M Zhai L Zhang et al ldquohe distribution and compositioncharacteristics of siliceous rocks from Qinzhou Bay-HangzhouBay Joint Belt SouthChina constraint on the tectonic evolutionof plates in South ChinardquoThe ScientificWorld Journal vol 2013Article ID 949603 25 pages 2013
[17] C XueDevonian Hydrothermal Sedimentation in Qinling XirsquoanMap Press Xirsquoan China 1997
[18] H Li Y Zhou Z Yang et al ldquoDiagenesis and metallogenesisevolution of chert in west Qinling orogenic belt a case fromBafangshan-Erlihe Pb-Zn ore depositrdquo Journal of JilinUniversity(Earth Science Edition) vol 41 no 3 pp 715ndash723 2011
[19] H Li Y Zhou Z Yang et al ldquoA study of micro-area com-positional characteristics and the evolution of cherts fromBafangshan-Erlihe Pb-Zn ore deposit in Western Qinling Oro-genrdquo Earth Science Frontiers vol 17 no 4 pp 290ndash298 2010
[20] YChenHChen Y Liu et al ldquoProgress and records in the studyof endogenetic mineralization during collisional orogenesisrdquoChinese Science Bulletin vol 45 no 1 pp 1ndash10 2000
[21] S Vearncombe M E Barley D I Groves N J McNaughtonE J Mikucki and J R Veancombe ldquo326 Ga black smoker-typemineralization in the Strelley Belt Pilbara CratonWesternAustraliardquo Journal of the Geological Society vol 152 no 4 pp587ndash590 1995
[22] H Ohmoto and M B Goldhaber ldquoSulfur and carbon isotoperdquoin Geochemistry of Hydrothermal Ore Deposits H L BarnesEd pp 517ndash612 John Wiley amp Sons New York NY USA 3rdedition 1997
[23] G Zhang B Zhang and X Yuan Qinling Orogen and Conti-nental Dynamics Science Beijing China 2001
[24] G Zhang Y Dong and A Yao ldquoThe crustal compositionsstructures and tectonic evolution of the Qinling orogenic beltrdquoGeology of Shanxi vol 15 no 2 pp 1ndash14 1997
[25] R Zeng S Liu C Xue and J Gong ldquoEpisodic-fluid processand effect of diagenesis and mineralization in evolution ofpaleozoic basins in SouthQinlingrdquo Journal of Earth Sciences andEnvironment vol 29 no 3 pp 234ndash239 2007
[26] W Yang ldquoOpening and closing history in east Qinling areardquoEarth Science vol 12 no 5 pp 487ndash493 1987
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 23
[27] J Liu M Zheng J Liu Y Zhou X Gu and B Zhang ldquoGeo-tectonic evolution and mineralization zone of gold deposits inwesternQinlingrdquoGeotectonica etMetallogenia vol 21 no 4 pp307ndash314 1997
[28] X GeWMa J Liu S Ren and S Yuan ldquoProspect of researcheson regional tectonics of Chinardquo Geology in China vol 40 no 1pp 61ndash73 2013
[29] J Ren Y Chen B Niu Z Liu and F Liu Tectonic Evolution andMineralization of the Continental Lithosphere in Eastern Chinaand Adjacent Regions Science Beijing China 1990
[30] M G Zhai and M Santosh ldquoMetallogeny of the North ChinaCraton link with secular changes in the evolving EarthrdquoGondwana Research vol 24 no 1 pp 275ndash297 2013
[31] K McClay and T Dooley ldquoAnalog modeling of pull-apartBasinsrdquo AAPG Bulletin vol 81 no 11 pp 1804ndash1826 1997
[32] Shanxi Bureau of Geology and Mineral Resources RegionalGeology of Shanxi Province Geological Publishing HouseBeijing China 1989
[33] Q Hu Y Wang R Wang J Li J Dai and S Wang ldquoOre-forming time of the Erlihe Pb-Zn deposit in the Fengxian-Taibaiore concentration area Shaanxi Province evidence from theRb-Sr isotopic dating of sphaleritesrdquoActa Petrologica Sinica vol28 no 1 pp 258ndash266 2012
[34] M Tian X Yuan Y Zhang and L Wang ldquoDiscussion of geo-logical prospecting in Erlihe Pb -Zn deposit FengxianrdquoMineralResources and Geology vol 18 no 2 pp 134ndash138 2004
[35] R Lv and H Wei ldquoThe geological characteristics and geneticinvestigation of Bafangshan stratabound polymetallic ores inShanxi provincerdquo Journal of Changrsquoan University vol 12 no 4pp 10ndash17 1990
[36] Y Zhou ldquoSedimentary geochemical characteristics of chertsof Danchi basin in Guangxi Provincerdquo Acta SedimentologicaSinica no 3 pp 75ndash83 1990
[37] Qinghai Bureau of Geology and Mineral Resources RegionalGeology of Qinghai Province Geological Publishing HouseBeijing China 1991
[38] Gansu Bureau of Geology and Mineral Resources RegionalGeology of Gansu Province Geological Publishing House Bei-jing China 1989
[39] Henan Bureau of Geology and Mineral Resources RegionalGeology of Henan Province Geological Publishing House Bei-jing China 1989
[40] Anhui Bureau of Geology and Mineral Resources RegionalGeology of Anhui Province Geological Publishing House Bei-jing China 1987
[41] G-C Zhao Y-HHe andM Sun ldquoTheXionger volcanic belt atthe southern margin of the North China Craton petrographicand geochemical evidence for its outboard position in thePaleo-Mesoproterozoic Columbia Supercontinentrdquo GondwanaResearch vol 16 no 2 pp 170ndash181 2009
[42] M l Cui L C Zhang B L Zhang and M T Zhu ldquoGeochem-istry of 178 Ga A-type granites along the Southern margin ofthe North China Craton implications for Xiongrsquoer magmatismduring the break-up of the supercontinent Columbiardquo Interna-tional Geology Review vol 55 no 4 pp 496ndash509 2013
[43] H Li Y Zhou L Zhang et al ldquoStudy on geochemistry anddevelopment mechanism of Proterozoic chert from XiongrsquoerGroup in southern region of North China Cratonrdquo ActaPetrologica Sinica vol 28 no 11 pp 3679ndash3691 2012
[44] S M Mclennan ldquoRare earth elements in sedimentary rocksinfluences of provenance and sedimentary processesrdquo Reviewsin Mineralogy vol 21 pp 169ndash200 1989
[45] S R Taylor and S M McLennan The Continental Crust ItsComposition and Evolution Blackwell Scientific PublicationsOxford UK 1985
[46] R W Murray M R B T Brink D C Gerlach G P RussIII and D L Jones ldquoRare earth major and trace elementcomposition of Monterey and DSDP chert and associated hostsediment assessing the influence of chemical fractionationduring diagenesisrdquo Geochimica et Cosmochimica Acta vol 56no 7 pp 2657ndash2671 1992
[47] K Bostrom and M N A Peterson ldquoThe origin of aluminum-poor ferromanganoan sediments in areas of high heat flow onthe East Pacific RiserdquoMarine Geology vol 7 no 5 pp 427ndash4471969
[48] R Sugisaki and T Kinoshita ldquoMajor element chemistry ofthe sediments on the central Pacific Transect Wake to TahitiGH80-1 cruiserdquo in Geological Survey of Japan Cruise Report AMizuno Ed vol 18 no 293ndash312 1982
[49] P A Rona ldquoHydrothermal mineralization at oceanic ridgesrdquoCanadian Mineralogist vol 26 pp 431ndash465 1988
[50] G Zhang and H Cai ldquoDiscussion on Origin of Dachang poly-metallic ore deposit in Guangxi Provincerdquo Geological Reviewvol 33 no 5 pp 426ndash436 1987
[51] P G Spry and L T Bryndzia Regional Metamorphism of OreDeposits and Genetic Implications VSP Utrecht The Nether-lands 1990
[52] MAdachi K Yamamoto andR Sugisaki ldquoHydrothermal chertand associated siliceous rocks from the northern Pacific theirgeological significance as indication od ocean ridge activityrdquoSedimentary Geology vol 47 no 1-2 pp 125ndash148 1986
[53] R W Murray ldquoChemical criteria to identify the depositionalenvironment of chert general principles and applicationsrdquoSedimentary Geology vol 90 no 3-4 pp 213ndash232 1994
[54] M Baltuck ldquoProvenance and distribution of tethyan pelagic andhemipelagic siliceous sediments pindos mountains GreecerdquoSedimentary Geology vol 31 no 1 pp 63ndash88 1982
[55] Z Tang and Y Zeng ldquoPetrology geochemistry and origin ofcherts in the uraniferous formations Middle Silurian WestQinling rangerdquo Acta Petrologica Sinica no 2 pp 62ndash71 1990
[56] D Wang ldquoCharacteristics and origin of siliceous rocks fromYarlung Zangbo deep fracture in Tibet Chinardquo in TibetanPlateau Comprehensive Survey Group of Chinese Academy ofScience Sedimentary Rocks in South Tibet pp 1ndash86 SciencePress Beijing China 1981
[57] S S Sun ldquoLead isotopic study of young volcanic rocks frommid-ocean ridge ocean islands and island arcsrdquo PhilosophicalTransactions of the Royal Society of London vol A297 no 1431pp 409ndash445 1980
[58] A D Saunders and J Tarney ldquoGeochemical characteristics ofbasaltic volcanism within back-arc basinrdquo in Marginal BasinGeology B P Kokelaar and M F Howells Eds pp 59ndash76 TheGeological Society London UK 1984
[59] B L Weaver and J Tarney ldquoEmpirical approach to estimatingthe composition of the continental crustrdquo Nature vol 310 no5978 pp 575ndash577 1984
[60] V Marchig H Gundlach P Moller and F Schley ldquoSomegeochemical indicators for discrimination between diageneticand hydrothermal metalliferous sedimentsrdquo Marine Geologyvol 50 no 3 pp 241ndash256 1982
[61] G H Girty D L Ridge C Knaack D Johnson and R K Al-Riyami ldquoProvenance and depositional setting of paleozoic chertand argillite Sierra Nevada Californiardquo Journal of SedimentaryResearch vol 66 no 1 pp 107ndash118 1996
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
24 The Scientific World Journal
[62] J M Peter and S D Scott ldquoMineralogy composition and fluid-inclusionmicrothermometry of seafloor hydrothermal depositsin the Southern Trough of Guaymas Basin Gulf of CaliforniardquoCanadian Mineralogist vol 26 pp 567ndash587 1988
[63] K Bostrom T Kraemer and S Gartner ldquoProvenance and accu-mulation rates of opaline silica Al Ti Fe Mn Cu Ni and Coin Pacific pelagic sedimentsrdquo Chemical Geology vol 11 no 1-2pp 123ndash148 1973
[64] KM Yarincik RWMurray TW Lyons L C Peterson andGH Haug ldquoOxygenation history of bottomwaters in the CariacoBasin Venezuela over the past 578000 years Results fromredox-sensitive metals (Mo V Mn and Fe)rdquo Paleoceanographyvol 15 no 6 pp 593ndash604 2000
[65] S Sun Q Zhang and Q Qin ldquoSedimentary geochemistrysignificance of SrBa-VNirdquo inNewExploration ofMineral Rockand Geochemistry Z Ouyang Ed pp 128ndash130 EarthquakePublishing House Beijing China 1993
[66] Y Sui GWu and C Qi ldquoMafic-ultramafic rock association andthe mineralization-forming specialization of Cr-Ni depositrdquoJournal of Jiling University vol 34 no 2 pp 201ndash205 2004
[67] R W Murray M R Buchholtz Ten Brink D C Gerlach G PRuss III and D L Jones ldquoRare earth major and trace elementsin chert from the Franciscan Complex and Monterey GroupCalifornia assessing REE sources to fine-grained marine sed-imentsrdquo Geochimica et Cosmochimica Acta vol 55 no 7 pp1875ndash1895 1991
[68] R W Murray M R Buchholtz Ten D L Brink D C Gerlachand P G Russ ldquoRare earth elements as indicators of differentmarine depositional environments in chert and shalerdquo Geologyvol 18 no 3 pp 268ndash271 1990
[69] R W Murray M R Buchholtzten Brink H J Brumsack DC Gerlach and G P Russ III ldquoRare earth elements in JapanSea sediments and diagenetic behavior of CeCelowast results fromODP Leg 127rdquo Geochimica et Cosmochimica Acta vol 55 no 9pp 2453ndash2466 1991
[70] H Elderfield R Upstill-Goddard and E R Sholkovitz ldquoTherare earth elements in rivers estuaries and coastal seas and theirsignificance to the composition of ocean watersrdquo Geochimica etCosmochimica Acta vol 54 no 4 pp 971ndash991 1990
[71] A Michard F Albarede G Michard J F Minster andJ L Charlou ldquoRare-earth elements and uranium in high-temperature solutions from east pacific rise hydrothermal ventfield (13 ∘N)rdquo Nature vol 303 no 5920 pp 795ndash797 1983
[72] J F Scott and S P S Porto ldquoLongitudinal and transverse opticallattice vibrations in quartzrdquo Physical Review vol 161 no 3 pp903ndash910 1967
[73] Y Ke and H Dong Analysis Chemistry The Third VolumeAnalysis spectrum Chemical Industry Press Beijing China 2ndedition 1998
[74] M Ostroumov E Faulques and E Lounejeva ldquoRaman spec-troscopy of natural silica in Chicxulub impactite MexicordquoComptes Rendus Geoscience vol 334 no 1 pp 21ndash26 2002
[75] M Yoshikawa K Iwagami N Morita T Matsunobe and HIshida ldquoCharacterization of fluorine-doped silicon dioxide filmby Raman spectroscopyrdquo Thin Solid Films vol 310 no 1-2 pp167ndash170 1997
[76] B Y Lynne K A Campbell J N Moore and P R LBrowne ldquoDiagenesis of 1900-year-old siliceous sinter (opal-Ato quartz) at Opal Mound Roosevelt Hot Springs Utah USArdquoSedimentary Geology vol 179 no 3-4 pp 249ndash278 2005
[77] S Bernard K Benzerara O Beyssac et al ldquoExceptional preser-vation of fossil plant spores in high-pressure metamorphic
rocksrdquo Earth and Planetary Science Letters vol 262 no 1-2 pp257ndash272 2007
[78] P Xu R Li Y Wang Z Wang and Y Li Raman Spectrum inthe Earth Science Shanxi Science and Technology Press XirsquoanChina 1996
[79] F Pan X Yu X Mo et al ldquoRaman active vibrations of alumi-nosilicatesrdquo Spectroscopy and Spectral Analysis vol 26 no 10pp 1871ndash1875 2006
[80] Y Zhou W Fu Z Yang et al ldquoMicrofabrics of chert fromYarlung Zangbo Suture Zone and southern Tibet and its geo-logical implicationsrdquo Acta Petrologica Sinica vol 22 no 3 pp742ndash750 2006
[81] H Li M Zhai L Zhang et al ldquoStudy on microarea character-istics of calcite in late archaean BIF fromWuyang area in southmargin of north China craton and its geological significancesrdquoSpectroscopy and Spectral Analysis vol 33 no 11 pp 3061ndash30652013
[82] TArguirov TMchedlidzeVDAkhmetov et al ldquoEffect of laserannealing on crystallinity of the Si layers in SiSiO
2multiple
quantum wellsrdquo Applied Surface Science vol 254 no 4 pp1083ndash1086 2007
[83] B Champagnon G Panczer C Chemarin and B Humbert-Labeaumaz ldquoRaman study of quartz amorphization by shockpressurerdquo Journal of Non-Crystalline Solids vol 196 pp 221ndash226 1996
[84] M A Carpenter E K H Salje A Graeme-Barber B WruckM T Dove and K S Knight ldquoCalibration of excess thermody-namic properties and elastic constant variations associated withthe 120572 larrrarr 120573 phase transition in quartzrdquoAmericanMineralogistvol 83 no 1-2 pp 2ndash22 1998
[85] B Olinger and P M Halleck ldquoThe compression of 120572 quartzrdquoJournal of Geophysical Research vol 81 no 32 pp 5711ndash57141976
[86] S Shen and Z Li Materials Technology of Minerals and RocksChina University of Geosciences Press Wuhan China 2005
[87] D Ge H Tian and R Zeng Oryctognosy Concise TutorialGeological Press Beijing China 2006
[88] O W Florke B Kohler-Herbertz K Langer and I TongesldquoWater in microcrystalline quartz of volcanic origin agatesrdquoContributions to Mineralogy and Petrology vol 80 no 4 pp324ndash333 1982
[89] G Hirth and J Tullis ldquoDislocation creep regimes in quartzaggregatesrdquo Journal of Structural Geology vol 14 no 2 pp 145ndash159 1992
[90] M Stipp H Stunitz R Heilbronner and S M Schmid ldquoTheeastern Tonale fault zone a ldquonatural laboratoryrdquo for crystalplastic deformation of quartz over a temperature range from250to 700∘Crdquo Journal of Structural Geology vol 24 no 12 pp 1861ndash1884 2002
[91] C W Passchier and R A J Trouw Microtectonics SpringerBerlin Germany 2nd edition 2005
[92] Y Zhou W Fu Z Yang et al ldquoGeochemical characteristicsof Mesozoic chert from Southern Tibet and its petrogenicimplicationsrdquoActa Petrologica Sinica vol 24 no 3 pp 600ndash6082008
[93] F Han and R W Harrison ldquoEvidence for exhalative origin forrocks and ores of the Dachang tin polymetallic field the ore-bearing formation and hydrothermal exhalative sedimentaryrocksrdquoMineral Deposits vol 8 no 2 pp 25ndash40 1989
[94] S Zhang T Li and L Wang ldquoGeochemistry and genesis of thechangkeng large superlarge gold silver deposit guangdongprovincerdquoMineral Deposits vol 17 no 2 pp 125ndash134 1998
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
The Scientific World Journal 25
[95] H Liang H Yu P Xia and X Wang ldquoCharacteristics and gen-esis of Changkeng gold-hosting siliceous rock in the rimof southwestern Sanshui Basin middle Guangdong ProvinceChinardquo Geochimica vol 38 no 2 pp 195ndash201 2009
[96] E C Dapples ldquoSilica as an agent in diagenesisrdquo in Diagenesisin Sediments G Larsen and G V Chilingar Eds Diagenesis inaediments pp 323ndash342 Diagenesis in Sediments Amsterdam1967
[97] J Liu and M Zhen ldquoNew origin of siliceous rocksmdashhydro-thermal sedimentationrdquo Acta Geologica Sichuan vol 11 no 4pp 251ndash254 1991
[98] C Feng and J Liu ldquoThe investive actuslity and mineralizationsignificance of chertsrdquoWorld Geology vol 20 no 2 pp 119ndash1232001
[99] H Li Chert sedimentary system and its indications on tectonicevolution petrogenesis and mineralization in northern andsouthern margins of Yangtze Platform China [PhD thesis] SunYat-Sen University GuangZhou China 2012
[100] K B Krauskopf ldquoFactors controlling the concentrations ofthirteen rare metals in sea-waterrdquo Geochimica et CosmochimicaActa vol 9 no 1-2 pp 1ndash32 1956
[101] S E Calvert ldquoSedimentary geochemistry of siliconrdquo in SiliconGeochemistry and Biogeochemistry S R Aston Ed pp 143ndash186Academic Press London UK 1983
[102] G Zhang Q Meng and S Lai ldquoTectonics and structure ofQinling orogenic beltrdquo Science inChinaB vol 25 no 9 pp 994ndash1003 1995
[103] Q Meng G Zhang Z Yu and Z Mei ldquoLate Paleozoicsedimentation and tectonics of rift and limited ocean basin atsouthern margin of the Qinlingrdquo Science China Earth Sciencesvol 26 pp 28ndash33 1996
[104] S Lai G Zhang and X Pei ldquoGeochemistry of the Pipasiophiolite in the Mianlue suture zone South Qinling and itstectonic significancerdquo Geological Bulletin of China vol 21 no8-9 pp 465ndash470 2002
[105] K A Kormas M K Tivey K von Damm and A TeskeldquoBacterial and archaeal phylotypes associated with distinctmineralogical layers of a white smoker spire from a deep-seahydrothermal vent site (9∘N East Pacific Rise)rdquo EnvironmentalMicrobiology vol 8 no 5 pp 909ndash920 2006
[106] G Racki and F Cordey ldquoRadiolarian palaeoecology and radio-larites is the present the key to the pastrdquo Earth Science Reviewsvol 52 no 1ndash3 pp 83ndash120 2000
[107] Y Furukawa and S E OrsquoReilly ldquoRapid precipitation of amor-phous silica in experimental systems with nontronite (NAu-1)and Shewanella oneidensis MR-1rdquoGeochimica et CosmochimicaActa vol 71 no 2 pp 363ndash377 2007
[108] Y Li K O Konhauser D R Cole and T J Phelps ldquoMineralecophysiological data provide growing evidence for microbialactivity in banded-iron formationsrdquo Geology vol 39 no 8 pp707ndash710 2011
[109] IM Samson andM J Russell ldquoGenesis of the silvermines zinc-lead barite deposit Ireland fluid inclusion and stable isotopeevidencerdquo Economic Geology vol 82 no 2 pp 371ndash394 1987
[110] D R Cooke S W Bull R R Large and P J McGoldrickldquoThe importance of oxidized brines for the formation of Aus-tralian Proterozoic stratiform sediment-hosted Pb-Zn (sedex)depositsrdquo Economic Geology vol 95 no 1 pp 1ndash18 2000
[111] R W Hutchinson ldquoVolcanogenic sulfide deposits and theirmetallogenic significancerdquo Economic Geology vol 68 no 8 pp1223ndash1246 1973
[112] J KMortensen B VHall T Bissig et al ldquoAge and paleotectonicsetting of volcanogenic massive sulfide deposits in the Guerreroterrane of central Mexico constraints from U-Pb Age and Pbisotope studiesrdquo Economic Geology vol 103 no 1 pp 117ndash1402008
[113] S Wu Study of Hydrothermal Chimneys in the Mariana TroughChina Ocean Press Beijing China 1995
[114] Z Hou F Han L Xia et al Modern and Ancient Subma-rineHydrothermalMineralized Activities Geological PublishingHouse Beijing China 2003
[115] J W Lydon ldquoChemical parameters controlling the origin anddeposition of sediment-hosted stratiform lead-zinc depositsrdquo inShort Course in Sediment Hosted Stratiform Lead-Zinc DepositsD F Sangster Ed pp 175ndash250 Mineralogical Association ofCanada Victoria Canada 1983
[116] M J Russell ldquoMajor sediment-hosted zinc + lead depositsformation from hydrothermal convection cells that deependuring crustal extensionrdquo in Short Course in Sediment HostedStratiform Lead-Zinc Deposits D F Sangster Ed pp 251ndash282Mineralogical Association of Canada Victoria Canada 1983
[117] D L Huston B Stevens P N Southgate P Muhling and LWyborn ldquoAustralian Zn-Pb-Ag ore-forming systems a reviewand analysisrdquo Economic Geology vol 101 no 6 pp 1117ndash11572006
[118] D L Leach D C Bradley D Huston S A Pisarevsky R DTaylor and S J Gardoll ldquoSediment-hosted lead-zinc depositsin earth historyrdquo Economic Geology vol 105 no 3 pp 593ndash6252010
[119] FN Spiess KCMacdonald TAtwater et al ldquoEast PacificRisehot springs and geophysical experimentsrdquo Science vol 207 no4438 pp 1421ndash1433 1980
[120] S Qi Y Li Z Zeng W Liang H Wei and X Ning Lead-Zinc (Copper) Deposits of SEDEX Type in Qinling MountainsGeological Publishing House Beijing China 1993
[121] H D Holland ldquoGangue minerals in hydrothermal systemrdquo inGeochemistry of Hydrothermal Ore Deposits H L Barners Edpp 382ndash436 John Wiley amp Sons New York NY USA 1967
[122] P A Rona K Bostrom and S Epstein ldquoHydrothermal quartzvug from the Mid-Atlantic Ridgerdquo Geology vol 8 no 12 pp569ndash572 1980
Top Related