This article appeared in a journal published by Elsevier. The attachedcopy is furnished to the author for internal non-commercial researchand education use, including for instruction at the authors institution

and sharing with colleagues.

Other uses, including reproduction and distribution, or selling orlicensing copies, or posting to personal, institutional or third party

websites are prohibited.

In most cases authors are permitted to post their version of thearticle (e.g. in Word or Tex form) to their personal website orinstitutional repository. Authors requiring further information

regarding Elsevier’s archiving and manuscript policies areencouraged to visit:

http://www.elsevier.com/copyright

Author's personal copy

Oxidation zonation within the Emeishan large igneous province: Evidencefrom mantle-derived syenitic plutons

J. Gregory Shellnutt a,⇑, Yoshiyuki Iizuka b

a Department of Earth Sciences, National Taiwan Normal University, 88 Tingzhou Road Section 4, Taipei 11677, Taiwanb Institute of Earth Sciences, Academia Sinica, 128 Academia Road Section 2, Nankang, Taipei 11529, Taiwan

a r t i c l e i n f o

Article history:Received 29 November 2011Received in revised form 18 March 2012Accepted 19 March 2012Available online 3 April 2012

Keywords:Metaluminous syeniteA-type granitoidZr saturation thermometryOxygen fugacityEmeishan large igneous province

a b s t r a c t

The mantle-derived felsic plutonic rocks of the Emeishan large igneous province consist of peralkalineand metaluminous varieties. The peralkaline rocks appear to be formed by fractional crystallization ofmafic magmas whereas the metaluminous plutonic rocks appear to be derived by partial melting ofunderplated mafic rocks. The metaluminous Woshui pluton is 259.6 ± 0.5 Ma and contains alkali feldspar,clinopyroxene, magnesiohornblende, titanite, magnetite and quartz and was relatively volatile- and traceelement-rich and had an initial magmatic temperature of �720 �C ± 20 2r. The metaluminous Huangcaopluton is slightly younger (258.9 ± 0.7 Ma), contains alkali feldspar, fayalite, ferrosillite, ferrohornblende,quartz, magnetite and ferrohedenbergite, is volatile-poor and likely had higher magmatic temperatures(P850 �C). The mineral assemblages and trace element compositions (i.e. Eu/Eu� > 1, high V/Sc, high V/Ga) suggest relatively oxidizing magmatic conditions (i.e. fO2 P 0 FMQ) for the two plutons. The primarychemical differences between the two plutons are their volatile content and source fertility. Neighboringthe metaluminous plutons is a peralkaline pluton which also shows evidence for relatively oxidizingmagmatic conditions whereas other mantle-derived granitic plutons to the north and south show evi-dence for reducing conditions. The syenitic magmas within the central part of the Panxi region werelikely oxidized due to variability of the oxidation state of the original source material and thereforethe region may represent an ‘oxidized zone’ within the Emeishan large igneous province.

� 2012 Elsevier Ltd. All rights reserved.

1. Introduction

Many continental large igneous provinces (LIPs) are composedprimarily of mafic rocks (Coffin and Eldholm, 1994; Jerram andWiddowson, 2005; Sheth, 2007; Bryan and Ernst, 2008). The basal-tic rocks of LIPs can reveal important information on the source,structure and geological environment of their formation (Pearceand Cann, 1973; Kress and Carmichael, 1991; Smith and Asimow,2005; Herzberg and Asimow, 2008). Equally important, althoughvolumetrically minor, are the silicic plutonic rocks of LIPs. Thesilicic plutonic rocks of Phanerozoic mafic-LIPs are rarely exposedbecause they are often found beneath the thick piles of flood bas-alts or within the unexposed stable craton in which they intruded.Magmatic conditions such as the relative oxidation state, volatilecontent, pressure and temperature can be deduced using mineralchemistry and whole rock geochemical data and can thereforeprovide important information on their origin as well as the mag-matic conditions within a LIP (Buddington and Lindsley, 1964;Frost et al., 1988; Frost and Lindsley, 1992; Pang et al., 2008,2010; Wang et al., 2008). Constraining the magmatic conditions

within a LIP can help to understand the origin of mineral deposits,magma–country rock interactions and possibly the source condi-tions (Ganino et al., 2008; Zhou et al., 2008; Shellnutt et al.,2009a; Pang et al., 2010).

Exposed within the central part of the Late Permian Emeishanlarge igneous province (ELIP) are numerous silicic plutonic rockswhich have diverse origins. For example the peralkaline graniticrocks appear to be derived by fractional crystallization of mantlederived mafic magmas whereas some metaluminous and peralu-minous granitoids are mixtures of crustal and mafic melts (Luoet al., 2007; Shellnutt and Zhou, 2007; Shellnutt et al., 2009a,2011a; Shellnutt and Jahn, 2010; Xu et al., 2008; Zhong et al.,2007, 2009). There are at least two metaluminous plutons whichare isotopically similar to the peralkaline rocks indicating that theyoriginated from the same mantle-derived source (Shellnutt andZhou, 2007, 2008). However, in spite of the similar isotopic compo-sitions, the metaluminous plutons have different trace elementcompositions which suggest they evolved differently from theperalkaline rocks. The principle chemical differences between themetaluminous plutons and the peralkaline plutons is their Eu/Eu�

values and primitive mantle normalized incompatible elementpatterns (Shellnutt et al., 2011b). The Eu/Eu� values of the metalu-minous rocks is >1 whereas in the peralkaline rocks their valueis <1. The difference in Eu/Eu� values is significant because it

1367-9120/$ - see front matter � 2012 Elsevier Ltd. All rights reserved.http://dx.doi.org/10.1016/j.jseaes.2012.03.011

⇑ Corresponding author. Fax: +886 2 2933 3315.E-mail address: jgshelln@ntnu.edu.tw (J.G. Shellnutt).

Journal of Asian Earth Sciences 54–55 (2012) 31–40

Contents lists available at SciVerse ScienceDirect

Journal of Asian Earth Sciences

journal homepage: www.elsevier .com/locate / jseaes

Author's personal copy

implies that the two rocks cannot be generated by the same pro-cess. For example, fractionation of feldspar from a mafic parentalmagma would produce a residual liquid composition with a Eu/Eu� < 1. Furthermore, Shellnutt and Iizuka (2011) suggested thatthe relative oxidation state of the peralkaline granitic rocks werevariable. The Panzhihua and Taihe silica-saturated peralkalinegranitic plutons show evidence of a relative reduced mineralassemblage (e.g. aenigmatite and ilmenite) whereas the Baimasilica-saturated peralkaline syenitic pluton shows evidence of arelatively oxidized mineral assemblage (e.g. titanite, magnetiteand quartz). It is unclear why the peralkaline rocks show evidencefor contrasting oxidation states but it could be due to country rockinteractions, original source magma conditions or it could beintrinsic to the specific region of the ELIP which the granitoidsformed.

The two mantle-derived metaluminous plutons, Woshui andHuangcao, are located in the same area as the Baima peralkalinesyenitic pluton. The positive chondrite normative Eu-anomaliesof the metaluminous plutons suggest that they may have been rel-atively oxidized magmas (Weill and Drake, 1973; Drake, 1975).The new mineral chemistry and geochemical data of the Woshuiand Huangcao mantle-derived metaluminous silicic plutons pre-sented in this study confirm that there are specific regions withinthe central part of the Inner Zone of the ELIP that have unique mag-matic characteristics, e.g. relatively oxidized conditions.

2. Background geology

The ELIP is exposed over an area of �0.3 � 106 km2 primarily insouthwestern China with correlative units within the Tibetan

plateau (e.g. Songpan-Ganze terrane) and northern Vietnam (Aliet al., 2005) (Fig. 1). The basaltic rocks are volumetrically the larg-est component of the ELIP with total thickness ranges from 0.2 to5.0 km whereas the picrites, basaltic-andesites, trachytes andrhyolites are volumetrically minor (Song et al., 2001, 2006; Xuet al., 2001, 2010; Xiao et al., 2004; Fan et al., 2008; Hanski et al.,2010; Shellnutt and Jahn, 2010; Anh et al., 2011). The ELIP canbe broadly subdivided into three approximately concentric zoneswhich correspond to crustal thickness (Xu et al., 2004). The InnerZone has the thickest crust which progressively thins to the Outerzone. The structural zonation of the ELIP is attributed to underplat-ing of the Yangtze Block by the Emeishan mantle plume head.Within the Inner Zone there are numerous mafic–ultramafic intru-sions which contain Fe–Ti–V oxide deposits or Ni–Cu sulfidedeposits many of which are located between the cities of Panzhi-hua and Xichang (Panxi) (Zhou et al., 2008; Shellnutt et al.,2011a). Also exposed within the Panxi region are numerous gra-nitic plutons. The granitic plutons rocks have diverse origins assome are derived from basaltic magmas or partial melting of thecrust or mixing between crustal-derived magmas and basalticmagmas (Shellnutt et al., 2011b).

The granitic rocks of the ELIP range in composition from peralu-minous to peralkaline (Shellnutt et al., 2011b). The peraluminousgranitic rocks are considered to be derived primarily by partialmelting of the crust (Shellnutt and Zhou, 2007; Zhong et al.,2007). In contrast the peralkaline rocks are considered to bederived by fractional crystallization of mantle derived mafic mag-mas which resemble Emeishan basalts (Shellnutt et al., 2009a,2011a; Shellnutt and Jahn, 2010). The origins of the metaluminousrocks are more complicated. Some metaluminous granitic rocks

Mesozoic-Quaternarystrata

Basalts

Palaeozoic strata

Neoproterozoic complexes(Kangding granitoids)

Gabbroic intrusions

EL

IP

Peralkaline Granitoids

Xichang

27 20´ No

26 40´ No

102 00´ Eo

26 40´ No

102 00´ Eo

27 20´ No

N

Miyi

30 km

HuangcaoPluton

BaimaPluton

Metaluminous Granitoids

102 30´ Eo

102 30´ Eo

Panzhihua

Peraluminous Granitoids

Kunlun-Tibet Domain

Yangtze Block

Hong Kong

North China Craton

Cathay

sian B

lock

Paleo-AsianOrogenic Belt

Beijing

Emeishan

Taipei

Panxi region

PanzhihuaPluton

WoshuiPluton

TaihePluton

Fig. 1. Simplified geological map of the Panzhihua-Xi Chang region (Panxi) showing the location and distribution of Late Permian granitic rocks.

32 J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40

Author's personal copy

represent mingling or mixing between basaltic magmas and crus-tally derived felsic magmas however there are a few which appearto be derived from mafic magmas with little or no crustal assimi-lation (Luo et al., 2007; Shellnutt and Zhou, 2007, 2008; Zhonget al., 2007; Xu et al., 2008; Shellnutt et al., 2011a). The Woshuiand Huangcao syenitic plutons are two examples of metaluminoussyenites which have isotopic characteristics similar to the peralka-line granitic rocks and show little evidence of crustal assimilation(e.g. Nb/U > 45, Th/NbPM < 1.6, ISr = 0.7043–0.7068, eNd(T) = + 1.5to +3.1). They are referred to as mantle-derived because they arethe products of differentiation of mantle-derived mafic magmas.

The Woshui pluton is located to the east of the Baima igneouscomplex (BIC) and is dated at 259.6 ± 0.5 Ma whereas the Huang-cao pluton is located to the west of the BIC and is dated at258.9 ± 0.7 Ma (Shellnutt et al., 2012). The metaluminous plutonshave similar whole rock Sr–Nd radiogenic and zircon Hf isotopicvalues as the Emeishan flood basalts and the peralkaline plutonsof the Panxi region (i.e. ISr = 0.7044–0.7068; Nd(T) = +1.5 to +3.2).

3. Petrography

3.1. Woshui syenite

The syenites in Woshui consist of alkali feldspar which has ser-rated boundaries and angular to sub-round shapes. The alkali feld-spar varies in size from 2 cm to <0.1 cm and comprises �80% of themineral mode and shows perthite, microcline perthite and micro-perthite exsolution textures. Amphibole (�15 vol.%) is the princi-ple mafic mineral interstitial to the feldspar and often formsclusters with Fe–Ti oxides and clinopyroxene. The angular shapeand size (6 1 cm) of the amphibole is determined by cleavageplanes and the space between the earlier formed crystals. Com-monly within the cluster of amphibole and clinopyroxene are small(60.1 cm), irregularly shaped magnetite and ilmenite (�2 vol.%)which host small euhedral apatite crystals (<1 vol.%). There areaccessory amounts of zircon, chevkinite and titanite.

3.2. Huangcao syenites

The Huangcao syenites are fresh, medium to coarse grained andcomposed primarily of alkali feldspar (�75–80 vol.%), clinopyrox-ene (<10 vol.%) and fayalite (65 vol.%). Other accessory mineralsinclude ilmenite (62 vol.%), magnetite (62 vol.%), and apatite(61 vol.%), plagioclase (61 vol.%), quartz (61 vol.%), amphibole(61 vol.%), sulfides (61 vol.%), biotite (61 vol.%) and ferrosillite(<1 vol.%). Typically, mafic, oxide and sulfide minerals form clus-ters interstitial to the feldspars, although it is common to have asingle independent mafic silicate, oxide or sulfide mineral. Theabundance of hypersolvus feldspar and Fe-rich silicate mineralssuggests the rock was dry or had very little H2O content when itformed.

4. Method and data processing

A total of eight syenite samples, three from the Woshui pluton(GS03-113, -117, -118) and five from the Huangcao pluton (GS03-123, -125, -127, -137, -139), were selected for analyses. Quantita-tive mineral analysis was carried out by a field emission electronprobe microanalyzer (FE-EPMA: JEOL JXA-8500F) equipped withfive wavelength dispersive spectrometers (WDS) at the Instituteof Earth Sciences, Academia Sinica in Taipei. Secondary electronand backscattered electron images were used to guide the analysison target positions of minerals. A 2 lm defocused beam was usedat an accelerating voltage of 12 kV and a beam current of 5 nA. Themeasured X-ray intensities were corrected by ZAF method. For sil-

icates and oxides analyses, the standards and diffracting crystalsused are as follows: wollastonite for Si with TAP and for Ca withPET crystal, rutile for Ti with PET, corundum for Al with TAP, chro-mium oxide for Cr with PET, fayalite for Fe with LiF, tephroite forMn with PET, pyrope for Mg with TAP, albite for Na with TAP, adu-laria for K with PET, apatite for P with PET, sodalite for Cl with PET,and fluorite for F with TAP. The X-ray peak counting time for eachelement is 10 s and both upper- and lower-side background count-ing times are 5 s each.

For the analysis of apatite, the experimental conditions were asfollows: a 2 lm defocused beam, an accelerating voltage of 12 kVand a beam current of 6 nA. The standards and diffracting crystalsare fluorite for F with LDE1, apatite for Ca and P with PET, rutile forTi with PET, hematite for Fe with LiF, and jadeite for Na with TAP.The peak and the backgrounds counting time for F and S are 10 sand 5 s, respectively; and for Ca, Na, Fe and Ti are 20 s and 10 s,respectively.

The WinAmphcal program, based on the nomenclature andclassification scheme of amphiboles by the International Mineral-ogical Association (IMA), was used to classify and process theamphibole data (Leake et al., 2004; Yavuz, 2007). The structuralformulae are calculated based on minimum Fe3+, 13eCNK, tetrahe-dral Si and Al = 8, and 23 oxygen atoms. All of the mineral data canbe found in the online Supplementary data Table S1.

5. Results

5.1. Calcic amphiboles

The calcic amphiboles from the Woshui syenites are more vari-able in composition than the Huangcao syenites and are classifiedas magnesiohornblende or edenite. The TiO2 (0.1–1.8 wt.%), Al2O3

(0.9–6.6 wt.%), TFeO (11.9–16.1 wt.%), MgO (12.2–15.4 wt.%), CaO(8.5–12.7 wt.%), Na2O (0.2–2.9 wt.%) and K2O (0.1–1.1 wt.%) allshow significant variability. The F content of the amphiboles is moreconsistent and all but three analyses range from 0.9 to 1.8 wt.%.

The calcic amphiboles from the Huangcao pluton are classifiedas either ferro-hornblende or ferro-edenite but both have similarcompositions with MgO (3.9–4.7 wt.%), CaO (8.9–10.7 wt.%), TFeO(27.7–29.9 wt.%) and TiO2 (0.8–2.1 wt.%). In contrast with theamphiboles of the Woshui syenites, the halogen content of theHuangcao amphiboles is low with F between 0.1 and 0.4 wt.%and Cl between 0.1 and 0.5 wt.%.

5.2. Clinopyroxene

The clinopyroxene from the Woshui syenites classify as diop-side–augite within the pyroxene quadrilateral and have composi-tions of Wo41–47En31–38Fs19–27 whereas the clinopyroxene fromthe Huangcao syenites fall within the augite-hedenbergite fieldwith compositions distinctly more Fe-rich ranging from Wo36–

48En12–18Fs38–49 and best described as ferrohedenbergite (Fig. 2).Both types of clinopyroxenes have similar range in minor elementssuch as TiO2 (<0.6 wt.%), Al2O3 (<0.7 wt.%) and MnO (1.2–1.9 wt.%)although the diopside-augites have higher Na2O (0.9–1.7 wt.%)content than ferrohedenbergites Na2O (<0.8 wt.%). In terms of theirbulk compositions the clinopyroxenes within Woshui and Haung-cao syenites are nearly antithetical with respect to their Mg and Fecontents.

5.3. Ferrosillite

Orthopyroxene was found and analyzed in a few samples fromthe Huangcao pluton. Although it is not unusual for orthopyroxeneto be found in rocks of this nature it is still not very common and

J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40 33

Author's personal copy

represents < 1 vol.%. The orthopyroxene crystal have low contentsof Al2O3 (<0.75 wt.%), TiO2 (<0.2 wt.%) and CaO (<1.5 wt.%). Thecrystals have compositional range of Fs73–80Rh3–5En13–22.

5.4. Fayalite

Fayalite is only observed within the Huangcao pluton and is al-most pure end-member composition as it has a narrow composi-tional range of Fa94–98. Silica ranges from 29.9 to 30.9 wt.% withMnO from 3.5 to 5.8 wt.% and MgO from 0.9 to 2.2 wt.%. There ap-pears to be no systematic variation of any major elements in thefayalite.

5.5. Titanite

Titanite is observed only within the Woshui syenites. Some ofthe analyses sum to <97 wt.% which is likely related to the amountof trace elements within some of the titanite as it can contain sig-nificant quantities of LREE, Y and high field strength elements (e.g.Nb, Hf, Zr, U) (Sahama, 1946; Higgins and Ribbe, 1976; Ribbe,1980). The total iron content as expressed as Fe3+ is variable andranges from 1.3 wt.% to 5.2 wt.%. The higher values (>3 wt.%) ofFe2O3 wt.% are unusual as most reported titanite compositionsare < 3 wt.% (Ribbe, 1980; Deer et al., 1997a; Della Ventura andBellatreccia, 1999; Frost et al., 2000). The titanite which have thehighest Fe2O3 wt.% tend to have the lowest TiO2 wt.%. The trace ele-ments (e.g. REE, Zr, Nb, Y) of the titanite are variably concentratedbetween 0.4 wt.% and 5.8 wt.%. The F content is also variable andcan be as high as 1.0 wt.%.

5.6. Apatite

The apatite from the Woshui and Huangcao syenites is fluorine-rich and contains from 3.6 wt.% to 6.0 wt.% and from 4.0 wt.% to5.7 wt.%, respectively. The Cl (<0.2 wt.%) and TFeO (<0.8 wt.%)concentrations are low. There does not appear to be a substantialcompositional difference between the apatites from the twoplutons.

5.7. Ilmenite and magnetite

The ilmenite from the Woshui syenites have variable TiO2

(46.1–52.3 wt.%), TFeO (40.4–46.7) and MnO (4.2–7.4 wt.%) con-tents and low concentrations of Al2O3 (<0.4 wt.%). The ilmenitefrom the Huangcao syenites contains have similar compositionswith 49.7–51.6 wt.% TiO2, 43.7–47.2 wt.% TFeO, 2.1–5.3 wt.% MnOand trace MgO (<0.1 wt.%). The MnO content of the ilmenite fromboth rocks is high but similar to those of evolved felsic intrusions(O’Neill et al., 1989). The magnetite from both plutons is nearlypure end-member with TiO2 < 2.1 wt.% and total Fe between 89.1and 95.9 wt.%. There are trace amounts of Al2O3 (<0.8 wt.%),Cr2O3 (<0.2 wt.%), MnO (<0.6 wt.%) and MgO (<0.3 wt.%).

6. Discussion

6.1. Magmatic temperature estimates

The initial magmatic temperature of some metaluminous gra-nitic rocks can be determined by zircon saturation thermometry(Watson and Harrison, 1983; Hanchar and Watson, 2003; Milleret al., 2003). The calculated averaged M ([Na + K + 2Ca]/[Al � Si])value of the Woshui (M = 1.9 ± 0.04 2r) pluton is within the rangespecified by Watson and Harrison (1983) for reliable results how-ever the Huangcao pluton is not (M = 2.0 ± 0.07 2r). The calculatedtemperatures (TZr �C) for the Woshui syenites range from 620oC to810oC with an average value of 720 �C ± 20 2r (Fig. 3a). The tem-perature estimate is consistent with the inheritance-rich ‘cold’granites of Miller et al. (2003) however there is no geochemicalevidence to suggest that the Woshui pluton is derived from thecrust or has assimilated substantial amounts of crustal material(Shellnutt and Zhou, 2007; Shellnutt et al., 2009b). Therefore weconclude that the TZr �C estimate may represent the initial magmatemperature of the Woshui pluton but that it is not, geneticallyspeaking, similar to the inheritance granitoids as defined by Milleret al. (2003).

Since the Huangcao syenites do not have appropriate M valuesfor zircon saturation thermometry, alternative thermometers arerequired. The rocks contain ilmenite, magnetite, orthopyroxeneand clinopyroxene and therefore may be suitable for differentmineral-based geothermometers. The ilmenite–magnetite geo-thermometer produces a range of temperatures from 340 �C to560 �C at a pressure of 1 kbar with a mean value of �460 �C

enstatite ferrosillitePigeonite

Augitediopside

hedenbergite

En Fs

Wo

Fig. 2. Classification of the pyroxenes from the Woshui and Huangcao plutons(modified from Morimoto et al., 1988). Circles from Woshui, squares fromHuangcao.

Woshui Huangcao600

650

700

750

800

850

900

T ( C)Zr

o

720

C20

o

CPX-OPX

300

400

500

600

Woshui Huangcao

Tem

pera

ture

( C

)o

460C o

510

Co

(a)

(b)

Ilmenite-Magnetite

GS03-125GS03-127

Tem

pera

ture

( C

)o

Fig. 3. Temperature estimates of the Woshui and Huangcao plutons. (a) Range of Zrsaturation thermometry estimate of the Woshui pluton and clinopyroxene-ortho-pyroxene equilibrium temperatures of the Huangcao pluton using QUILF (Andersonet al., 1993). (b) Ilmenite–magnetite equilibrium temperatures using QUILF.

34 J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40

Author's personal copy

(Fig. 3b). The temperature estimates are too low to be magmatictemperatures as rocks with similar compositions are thought tohave temperatures of around 900 �C and we conclude that theylikely represent re-equilibration temperatures (Bohlen et al.,1980; Clemens et al., 1986; Anderson et al., 1993). Using theprogram QUILF of Anderson et al. (1993), we calculated the two-pyroxene temperatures. Anderson et al. (1993) recommended thatat least one factor among pressure, cpx composition and opx com-position be allowed to vary in order to minimize the effects of pres-sure sensitivity of the two-pyroxene geobarometers in the QUILFcalculations. For our calculation we fixed the pressure at 1 kbarand the cpx composition and allowed the opx composition to vary.We do not have constraints on the pressure of the Huangcao plutonalthough we believe it is shallow (<3 kbar) as evident from theperthitic alkali feldspar, fayalite + quartz, and the fact that itintruded the Baima gabbro–syenite complex which is thought tobe emplaced at shallow (e.g. 1 kbar) crustal levels (Bohlen et al.,1980; Shellnutt et al., 2009a). The highest temperatures which passthe ‘test reactions’ of QUILF have equilibration temperatures, i.e.the temperature which the two pyroxenes were in equilibrium,of 850 �C in sample GS03-127 (opx = B-45; cpx = A-21) and830 �C in sample GS03-125 (opx = B-21; cpx = B-20). The maxi-mum two-pyroxene temperatures are not the magmatic tempera-tures but indicate that cpx and opx may have been in equilibriumat temperatures P 850 �C and therefore the magmatic tempera-tures were likely higher than the Woshui pluton (Fig. 3a).

6.2. Magmatic oxidation states

The oxidation state of a parental magma can be estimated fromsome mineral assemblages, e.g. ilmenite and magnetite or titanite–quartz–magnetite (Buddington and Lindsley, 1964; Anderson et al.,1993; Wones, 1989). In the absence of full equilibrium mineralassemblages, partial mineral assemblages and trace element chem-istry may be indicative of the oxidation of the magma from whichthey crystallized (Wones, 1989; Takagi, 2004; Lee et al., 2010).

The Woshui syenites contain titanite-quartz-magnetite assem-blage which suggests fO2 conditions at or more oxidizing thanthe FMQ buffer (Wones, 1989; Xirouchakis and Lindsley, 1998).The ilmenite-magnetite pairs indicate sub-solidus temperatures(390 �C to 590 �C) and the calculated average oxidation state rela-tive to the FMQ buffer (DFMQ) is 1.66, indicating that at least thefinal stages of the magma were likely oxidized (Fig. 4a). There isfurther support for oxidized conditions, namely the bulk rock posi-tive Eu-anomalies and the titanite compositions. The Eu/Eu� valuesare between 1.1 and 1.9 with an average of 1.45 ± 0.1 2r (Fig. 4b).Positive Eu-anomalies are known within granitic rocks and is often,but not always, attributed to oxidized magmatic conditions asthere will be a preference for Eu3+ over Eu2+ in the liquid (Weilland Drake, 1973; Drake, 1975). The Eu/Eu� values and the rela-tively high Sr and Ba content also imply that the parental magmasdid not fractionate calcic-plagioclase or alkali feldspar because theresulting magma would have low (<1) Eu/Eu� values, low Sr andlow Ba contents. The titanite compositions may also indicate rela-tively high oxidation state. Most iron, although not all, containedwithin titanite is expected to be Fe3+ due to its substitution withTi or Al in the Ti-site of the crystal lattice (Ribbe, 1980; Frostet al., 2000). The high total Fe2O3 content of the rock may reflecta higher oxidation state. For example the titanite from the peralka-line Taihe and Panzhihua granitic plutons typically have low(<3.5 wt.%) total Fe2O3 in contrast with the Baima syenites whichhave total Fe2O3 up to 5.8 wt.%. The Baima syenites are consideredto have formed at or above the FMQ buffer whereas the Taihe andPanzhihua plutons are considered to have formed below the FMQbuffer (Shellnutt and Iizuka, 2011). Therefore, we conclude thelikely explanation for the high Eu/Eu� values and the titanite–

quartz–magnetite assemblage is that the parental magma wasoxidized (i.e. FMQ P 0).

The oxidation state of the Huangcao pluton on the other hand isless clear. The occurrence of both magnetite and ilmenite and anaverage Eu/Eu� value of 1.30 ± 0.1 2r suggests fO2 P FMQ althoughrocks with the QUILF assemblage (quartz–ulvospinel–ilmenite–fayalite) are thought to have fO2 < FMQ (Frost and Lindsley,1992; Frost and Frost, 1997; Frost et al., 1999). The Huangcao sye-nites however do not contain ulvospinel but rather nearly pureend-member magnetite with all crystals having TiO2 < 2.1 wt.%and the majority with <1 wt.%. The average calculated equilibriumfO2 conditions based on ilmenite and magnetite pairs isDFMQ = 2.4 but these conditions are likely sub-solidus equilibra-tion conditions and not necessary magmatic conditions (Fig. 4).Given the presence of magnetite and the high Eu/Eu� values, wesuggest that the magmatic fO2 conditions were likely above theFMQ buffer.

Some major and trace elements, such as V and Fe, are sensitiveto oxidation of their host magma, whereas other elements, e.g. Scand Ga, are insensitive. Lee et al. (2010) showed that Zn/FeT shouldbe lower in oxidize magmas than in reduced magmas. FurthermoreVT/Sc or VT/Ga should have higher values in oxidized magmas thanin relatively reducing conditions. Fig. 5 shows the VT/Sc and VT/Ga

0.0 0.5 1.0 1.5 2.0 2.5.01

.1

1

10

*aB /

aB

Eu / Eu*

Metaluminous

Peralkaline

WoshuiHuangcao

BaimaPanzhihuaTaihe

500 550 600-1

0

+1

+2

+3

QMF

Temperature ( C)o

U-3

U-4

U-5

U-10

I-95I-97

I-94

I-92(a)

(b)

Fig. 4. Oxidation state from mineral assemblages and geochemical data. (a)Temperature and oxidation equilibrium results for the ilmenite and magnetitefrom the Woshui and Huangcao plutons (fields from Frost et al., 1988). U = ulvos-pinel, I = ilmenite. DFMQ = log fO2 � log fO2(FMQ). (b) The Ba-anomaly versus theEu/Eu� value of the mantle-derived granitic rocks of the Panxi region. Ba/Ba� = [2 � BaPM/(RbPM + ThPM)] and Eu/Eu� = [2 � EuN/(SmN + GdN)] where PM = nor-malized to primitive mantle and N = normalized to chondrites of Sun andMcDonough (1989).

J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40 35

Author's personal copy

ratios of the mantle-derived A-type granitoids of the ELIP. TheBaima peralkaline syenites, Woshui syenites and Huangcao sye-nites have higher VT/Sc and VT/Ga ratios than the Panzhihua andTaihe peralkaline granites. The trace element ratios are consistentwith the interpretation that the Panzhihua and Taihe granites hadrelatively reducing fO2 conditions as compared to the Baima sye-nites (Shellnutt and Iizuka, 2011). Given that the Huangcao andWoshui syenites have higher VT/Sc and VT/Ga ratios, high Eu/Eu�

values and their mineral assemblages (e.g. magnetite bearing),we conclude that their magmas were likely oxidized (i.e.FMQ P 0).

6.3. Fluorine content of the amphiboles

Amphiboles are important reservoirs of magmatic volatiles (e.g.OH, Cl, F) in plutonic rocks and their composition or type (e.g. so-dic, calcic or sodic-calcic) is related to temperature, oxygen fugac-ity (fO2) and alkalinity (Charles, 1977; Mitchell, 1990; King et al.,2000; Scaillet and MacDonald, 2001, 2003). Fluorine is an impor-tant constituent element in some granitic rocks and can greatlyinfluence the melting temperature of rocks, magmatic oxidationstate and trace element partitioning within magmas (Manning,1981; Keppler, 1993; Taylor and Fallick, 1997). Therefore knowingthe F-content of a rock is helpful in identifying potential petrolog-ical processes which may influence the evolution of magmaticrocks.

Within the Woshui syenites, amphiboles comprise �15 vol.% ofthe mineral mode whereas in the Huangcao syenites amphibolerepresent �1 vol.%. The amphiboles from the Woshui pluton aremagnesiohornblende whereas the amphiboles from the Huangcaopluton are ferrohornblendes. Other than apatite, amphibole is theprimary F-bearing mineral in both rocks and volumetrically moreabundant. The magnesiohornblendes have an average of�1.3 wt.% F compared to �0.2 wt.% F for the ferrohornblendes.Based on the model volume of apatite (observed to be �0.5 vol.%for both plutons) and amphibole, the bulk rock F estimates forthe Woshui and Huangcao plutons would be 0.21 wt.% and0.02 wt.% respectively. It is difficult to say if the estimates are rep-resentative of the parental magma because F is incompatible andvery mobile but we suggest that the order of magnitude differencebetween the F content of the amphiboles is indicative of themagmatic conditions when they crystallized and thus there wasa substantial difference between the initial bulk magmatic F con-tent of the two plutons during their development.

The Woshui pluton has an average TZr �C temperature estimateof �720oC ± 20 2r which is lower than the maximum two-pyrox-ene temperature estimates for the Huangcao pluton (i.e.830–850 �C). The difference in temperature may be related to thevolatile content. Manning (1981) showed that at 1 kbar, the Qz–Ab–Or system will melt at 730 �C in the absence of F whereas itwould melt at 690 �C with 1% F. The average F content of thehornblendes from the Woshui syenites is an order of magnitudehigher than the hornblendes from the Huangcao syenites suggest-ing the parental magma F content was higher in the Woshui plu-ton. The difference in F content of the parental magmas could bean important factor that explains why the Woshui syenites havelower temperature estimates than the Huangcao syenites. Keppler(1993) showed that F can enrich a magma in high field strengthelements (e.g. Nb, Ta, Hf, Ti, Zr). The Woshui pluton has higheraveraged concentrations of all of the trace elements including thehigh field strength elements (Fig. 6). Water content of both plutonswas probably low due to the presence of perthitic feldspar and lowvolatile (e.g. OH) amphiboles (Table S1). We suggest that the differ-ences in the temperature estimates and the concentration of traceelements are likely related to the initial concentration of F in theWoshui and Huangcao plutons.

6.4. Oxidation zonation within the Inner Zone of the ELIP?

The mantle-derived metaluminous plutons of the ELIP intrudedeither side of the Baima igneous complex (BIC) in the central partof the Panxi region. The Panxi region is located in the center ofthe Inner Zone of the ELIP which corresponds to a crustal thicknessof �60 km (Xu et al., 2004). Shellnutt and Iizuka (2011) identifiedthe titanite-quartz-magnetite assemblage and Mg-rich richteritewithin the peralkaline quartz syenites of the BIC and suggestedthat it represents fO2 conditions equal to or greater than theFMQ buffer. There are two other peralkaline alkali feldspar graniteslocated to the north and south of the Baima region which containsaenigmatite, ilmenite and Fe-rich richterite and were interpretedto have formed under relatively reducing (i.e. FMQ < 0) conditions.All three peralkaline granitoids are thought to formed by fractionalcrystallization of Emeishan basaltic magmas and that the differ-ences between the formation of the syenitic rocks and the graniticrocks was due to a combination of magmatic oxidation state andparental magma composition (Shellnutt et al., 2011a). The identifi-cation of the Woshui and Huangcao plutons also showing evidencefor oxidized magmatic conditions indicates that this region of theELIP may have been preferentially oxidized. It would seem thatthe relatively ‘oxidized’ Baima region is bookended by two rela-tively ‘reduced’ peralkaline granitic plutons.

.01 .1 1 10.01

.1

1

10

aG/

VT

V /ScT

Metaluminous

Peralkaline

WoshuiHuangcao

BaimaPanzhihuaTaihe

Higher ƒO2

Lower ƒO2

Fig. 5. VT/Ga versus VT/Sc of the mantle-derived granitic rocks of the Panxi region.Rocks with higher ratios may be indicative of an oxidized magma (Lee et al., 2010).T = total.

.1

1

10

100

1000

Cs Rb Ba Th U Ta Nb La Ce Sr Nd Hf Zr Sm Ti Tb Y

Sam

ple

/ Pri

miti

ve M

antle

WoshuiHuangcao

Fig. 6. Primitive mantle normalized incompatible element diagram showing therelatively enriched nature of the Woshui compared to the Huangcao pluton.Normalizing values of Sun and McDonough (1989). Whole rock data from Shellnuttand Zhou (2007, 2008).

36 J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40

Author's personal copy

It is uncertain why there would be differences in the oxidationstate of the magmas within the Panxi region however it could bedue to either heterogeneities within the magma source or to coun-try rock–magma interactions. There is conflicting evidence for therelative oxidation state of mantle derived magmas in general asmany basaltic rocks indicate fO2 conditions at or near the FMQbuffer and yet some mantle xenoliths show evidence for fO2 condi-tions near the IW buffer (Mathez, 1984; Lee et al., 2005, 2010). Thedifferences in the oxidation state may be due to degassing of car-bon-rich phases at low pressure, the nature of their source regions,magmatic differentiation or fluid flux (Mathez, 1984; Carmichael,1991; Lee et al., 2005; Frost and McCammon, 2008). Since theparental magmas of the mantle-derived peralkaline and metalumi-nous rocks of the ELIP are thought to be similar to the Emeishanmafic rocks we calculate the possible fO2 conditions of the Emei-shan basalts with both Fe2+ and Fe3+ reported and using the meth-od of Kress and Carmichael (1991). The results indicate that theEmeishan basalts have an average DFMQ value of +0.1 (Fig. 7). Ifthis value represents the oxidation state of the basaltic magmasthan the observation of the titanite–quartz–magnetite assemblagein the Baima and Woshui plutons and the positive Eu-anomalies of

the metaluminous plutons are consistent with the oxidation calcu-lation and we would expect ‘oxidizing’ assemblages in the mantle-derived ELIP granitoids. However, the aenigmatite-ilmenite assem-blage in the Panzhihua and Taihe peralkaline plutons suggestsrelatively reducing conditions (FMQ < 0) (Lindsley, 1971; Whiteet al., 2005). Therefore either the DFMQ estimate is incorrect orthat country rock-magma interactions prevented the Panzhihuaand Taihe peralkaline plutons from becoming oxidized. The latterinterpretation does not seem to hold because Ganino et al.

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.50

5

10

15

20

25

30Fr

eque

ncy

FMQ

Emeishan basaltsN = 100

FMQ = +0.1AVG

Fig. 7. Range of calculated fO2 values of the Emeishan basalts using the method ofKress and Carmichael (1991).

0 1 2 30.0

0.1

0.2

0.3

tO

eF/Og

M3

2

Na O/K O2 2

Slope = 0.18N = 34r' = 0.71

BaimaWoshuiHuangcao

Fig. 8. Variation trend of MgO/Fe2O3t versus Na2O/K2O of the Woshui andHuangcao plutons. The trend line suggests a chemical evolution within the Baimaperalkaline syenites whereas the Woshui and Huangcao plutons show data clustersindicative of partial melting. Whole rock data from Shellnutt and Zhou (2007, 2008)and Shellnutt et al. (2009a).

16

17

18

19

)%t

w(Ol

A3

2

60 61 62 63 64 6510.0

10.5

11.0

11.5

12.0

)%t

w(O

K+

Oa

N2

2

SiO (wt%)2

0.0

0.5

1.0

1.5

2.0

)%t

w(Og

M

P = 2 kbarH O = 2.0 wt%

O = FMQ 02

2

P = 2 kbarH O = 2.0 wt%O = FMQ 02

2

(a)

(b)

(c)

60 61 62 63 64 65

SiO (wt%)2

60 61 62 63 64 65

SiO (wt%)2

Fig. 9. Results of partial melt modeling using MELTS. The modeled trends suggestthat a volatile-rich magma similar to an Emeishan basalt could be the source of theWoshui pluton. The models assuming pressure = 2 kbar, H2O = 2.0 wt.%, fO2 = FMQ 0and a starting composition similar to sample CH02-10 of Song et al. (2006).

J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40 37

Author's personal copy

(2008) suggested that CO2 released from the marble and dolostonewall rock of the Panzhihua gabbroic intrusion may have increasedthe oxidation state of the parental magma to FMQ + 1.5 which en-able the formation of the oxide deposit. The elevated oxidationstate interpreted for the Panzhihua gabbro may be correct but itmeans that the oxidation state dropped to below the FMQ bufferby the time the granitic residual liquid formed. A similar modelmay be applicable to the Taihe gabbro-granite complex becauseit is compositionally similar to the Panzhihua complex but it doesnot explain why the elevated fO2 conditions persisted during thecrystallization of the Baima syenite nor for the formation of themetaluminous plutons.

If CO2-enrichement is required to increase the oxidation state ofthe parental magmas of the Panxi-oxide deposits, as suggested byGanino et al. (2008), then the Baima rocks are difficult to explain.Unlike the Panzhihua complex there is no clear contact relation-ship between carbonate rocks and the rocks of the Baima Complexand yet peralkaline quartz syenites with titanite-magnetite-quartzformed instead of peralkaline alkali feldspar granites withaenigmatite-ilmenite. Given the similarities between the layeredgabbroic rocks of the Panzhihua, Taihe and Baima it is reasonableto suggest they had similar magmatic conditions but why the Pan-zhihua and Taihe granitic rocks ended up with a reducing assem-blage and the Baima syenitic rocks with an oxidized assemblageis less obvious. There does not appear to be a clear reason for thevariability of the oxidation states of the mantle-derived plutonsof the Panxi region but it is possible that magma source heteroge-neity may have been a factor rather than country rock-magmainteractions and that the Panzhihua and Taihe gabbro-granite com-plexes may have been more reducing than previously believed. Incomparison, the metaluminous syenites are thought to have

formed by partial melting of underplated mafic rocks but are thesame age as the Baima complex suggesting the magmas did notspend enough time in the crust to become oxidized. We thereforeconclude that the elevated oxidation conditions are likely to beintrinsic to the Baima region.

6.5. Emplacement model of the metaluminous syenites

The Woshui and Huangcao plutons have very different mineralassemblages, temperature estimates and F content and yet thereare many similarities between the two syenites (i.e. Eu/Eu� values,normalized trace element patterns; high VT/Sc and VT/Ga ratios). Inthis section we bring together the available data in order to presenta possible emplacement model for the Woshui and Huangcaoplutons.

The Woshui and Huangcao plutons are thought to originate bypartial melting of underplated basaltic rocks which were injectedinto the crust during the eruption of the Emeishan basalts (Shell-nutt and Zhou, 2007, 2008). Their whole rock radiogenic Sr–Ndand zircon Hf isotopic data are indistinguishable from the Emei-shan mafic and felsic rocks and there is limited evidence for crustalassimilation (Shellnutt and Zhou, 2007, 2008; Shellnutt et al.,2009b). Fractional crystallization is ruled out as a process to formthe metaluminous syenites because they have positive primitivemantle normalized Ba-anomalies and chondrite normalizedEu-anomalies which indicates that feldspar did not fractionate. Incontrast the isotopically similar and spatially associated Baimaperalkaline pluton has negative anomalies of Ba and Eu (Shellnuttet al., 2009a). The comparison is exemplified in Fig. 8 which showsthe distinct trends of the three plutons. The Woshui and Huangcaoplutons show data clusters whereas the Baima pluton shows a

Mesozoic-Quaternarystrata

Basalts

Palaeozoic strata

Gabbroic intrusionsE

LIP

Peralkaline Granitoids

27 20´ No

26 40´ No

30 km

Metaluminous Granitoids

Peraluminous Granitoids

Kunlun-Tibet Domain

Yangtze Block

Hong Kong

North China Craton

Cathay

sian B

lock

Paleo-AsianOrogenic Belt

Beijing

ELIP

Taipei

Panxi region

Xichang

102 00´ Eo

102 00´ Eo

N

102 30´ Eo

102 30´ Eo

Panzhihua

TaihePluton

HuangcaoPluton Woshui

Pluton

PanzhihuaPluton

BaimaPluton

iyiM iyiM

oxidized zone

O2< FMQ 0

O FMQ 02

O2<

FMQ

0

O2<

FM

Q0

Fig. 10. Simplified geological map of the Panxi region showing the area which is interpreted to be relatively oxidized (FMQ P 0).

38 J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40

Author's personal copy

clear positive correlation between the Mg/Fe ratio and Na/K ratio.Partial melting was modeled for the Woshui pluton using the pro-gram MELTS and starting material similar to hydrated Emeishanbasalt (Ghiorso and Sack, 1995; Smith and Asimow, 2005). Sincethe original parental material is unknown it is impossible to verifythe exact starting composition however the best guessed composi-tion produces results which have reasonable agreement withknown compositions from the Woshui pluton (Fig. 9).

We suggest that after mafic magmas were injected into thecrust at �260 Ma some of them reach the surface and erupted asthe Emeishan flood basalts whereas others reached shallow levelsand differentiated into the Fe–Ti oxide bearing gabbro-granitoidcomplexes. The ELIP mafic magmas are likely to be derived bylow degrees of partial melting and are at or near the FMQ buffer(Fig. 10). Some basaltic magmas may have stalled at shallow tomid-crustal levels 625 km (Xu et al., 2004). Repeated injection ofbasaltic magmas may have induced partial melting of the under-plated (i.e. stalled) mafic rocks. The Woshui pluton was likelyderived from a more volatile- and trace element-rich source andthus required lower initial temperatures to melt. The Huangcaopluton on the other hand was emplaced shortly after the Woshuipluton and was likely volatile- and trace element-poor andrequired higher temperatures to melt. Crustal assimilation andfractional crystallization may have played a role in the furtherchemical evolution of each pluton however we suggest that thoseprocesses were not significant.

7. Conclusion

The mantle-derived metaluminous plutons of the Panxi regionhave mineral assemblages and trace element compositions indica-tive of relatively oxidizing conditions (e.g. fO2 P 0 FMQ). The dif-ferences in the major compositions of the two plutons are likelyrelated to their volatile content and source fertility. The Woshuipluton is older and was likely volatile- and trace element-richand required lower temperatures to melt underplated Emeishan-related mafic rocks whereas the Huangcao pluton is younger, vol-atile-poor, likely required higher temperatures to melt and had arelatively ‘depleted’ trace element source. The recognition of threerelatively oxidizing syenitic rocks within the same area may be dueto variability of the oxidation state of the original source materialfor the Emeishan basalts. The central part of the Inner Zone of theELIP in the Baima region may represent an oxidized zone.

Acknowledgements

We would like to thank Kwan-Nang Pang and Georg Zellmer fortheir comments on an earlier draft of this manuscript and the com-ments of J.G. Liou, Donggao Zhao and an anonymous reviewer. JGSwould like to thank E. William Shellnutt for his encouragement andsupport over the years. This study was supported by National Sci-ence Council of Taiwan grant #100-2116-M-003-006 to JGS and#97-2116-M-001-008 to YI.

Appendix A. Supplementary material

Supplementary data associated with this article can be found, inthe online version, at http://dx.doi.org/10.1016/j.jseaes.2012.03.011.

References

Ali, J.R., Thompson, G.M., Zhou, M.-F., Song, X.Y., 2005. Emeishan large igneousprovince, SW China. Lithosphere 79, 475–489.

Anderson, D.J., Lindsley, D.H., Davidson, P.M., 1993. QUILF: a pascal program toassess equilibria among Fe–Mg–Mn oxides, pyroxenes, olivine, and quartz.Computers and Geoscience 19, 1333–1350.

Anh, T.V., Pang, K.-N., Chung, S.-L., Lin, H.-M., Hoa, T.T., Anh, T.T., Yang, H.-.J., 2011.The Song Da magmatic suite revisited: A petrologic, geochemical and Sr–Ndisotopic study on picrites, flood basalts and silicic volcanic rocks. Journal ofAsian Earth Sciences 42, 1341–1355.

Bohlen, S.R., Essene, E.J., Boettcher, A.L., 1980. Reinvestigation and application toolivine-quartz-orthopyroxene barometry. Earth and Planetary Science Letters47, 1–10.

Bryan, S.E., Ernst, R.E., 2008. Revised definition of Large Igneous Provinces (LIPs).Earth-Science Reviews 86, 175–202.

Buddington, A.F., Lindsley, D.H., 1964. Iron–titanium oxide minerals and syntheticequivalents. Journal of Petrology 5, 310–357.

Carmichael, I.S.E., 1991. The redox states of basic and silicic magmas: a reflection oftheir source regions? Contributions to Mineralogy and Petrology 106, 129–141.

Charles, R.W., 1977. The phase equilibria of intermediate compositions of thepseudobinary Na2CaMg5Si8O22(OH)2-Na2CaFe5Si8O22(OH)2. American Journal ofScience 277, 594–625.

Clemens, J.D., Holloway, J.R., White, A.J.R., 1986. Origin of an A-type granite:experimental constraints. American Mineralogist 71, 317–324.

Coffin, M.F., Eldholm, O., 1994. Large igneous provinces: crustal structure,dimensions and external consequences. Reviews of Geophysics 32, 1–36.

Deer, W.A., Howie, R.A., Zussman, J., 1997a. Rock Forming Minerals Volume 1A:Orthosilicates. Geological Society of London. 919 p.

Della Ventura, G., Bellatreccia, F., 1999. Zr- and LREE-rich titanite from Tre Croci,Vico Volcanic complex (Latium, Italy). Mineralogical Magazine 63, 123–130.

Drake, M.J., 1975. The oxidation state of europium as an indicator of oxygenfugacity. Geochimica et Cosmochimica Acta 39, 55–64.

Fan, W., Zhang, C., Wang, Y., Guo, F., Peng, T., 2008. Geochronology andgeochemistry of Permian basalts in western Guangxi Province, southwestChina: evidence for plume–lithosphere interaction. Lithos 102, 218–236.

Frost, C.D., Frost, B.R., 1997. Reduced rapakivi-type granites: the tholeiiteconnection. Geology 25, 647–650.

Frost, B.R., Lindsley, D.H., 1992. Equilibria among Fe–Ti oxides, pyroxenes, olivine,and quartz: Part II. Application. American Mineralogist 77, 1004–1020.

Frost, D.J., McCammon, C.A., 2008. The redox state of Earth’s mantle. AnnualReviews of Earth and Planetary Sciences 36, 389–420.

Frost, B.R., Lindsley, D.H., Anderson, D.J., 1988. Fe–Ti oxide-silicate equilibria:assemblages with fayalitic olivine. American Mineralogist 73, 727–740.

Frost, C.D., Frost, B.R., Chamberlain, K.R., Edwards, B.R., 1999. Petrogenesis of the1.43 Ga Sherman batholith, SE Wyoming, USA: a reduced rapakivi-typeanorogenic granite. Journal of Petrology 40, 1771–1802.

Frost, B.R., Chamberlain, K.R., Schumacher, J.C., 2000. Sphene (titanite): phaserelations and role as a geochronometer. Chemical Geology 172, 131–148.

Ganino, C., Arndt, N.T., Zhou, M.-F., Gaillard, F., Chauvel, C., 2008. Interaction ofmagma with sedimentary wall rock and magnetite ore genesis in the Panzhihuamafic intrusion, SW China. Mineralium Deposita 43, 677–694.

Ghiorso, M.S., Sack, R.O., 1995. Chemical mass transfer in magmatic processes IV. Arevised and internally consistent thermodynamic model for the interpolationand extrapolation of liquid-solid equilibria in magmatic systems at elevatedtemperatures and pressures. Contributions to Mineralogy and Petrology 119,197–212.

Hanchar, J.M., Watson, E.B., 2003. Zircon saturation thermometry. Reviews inMineralogy and Geochemistry 53, 89–112.

Hanski, E., Kamenetsky, V.S., Luo, Z.-Y., Xu, Y.-G., Kuzmin, D.V., 2010. Primitivemagmas in the Emeishan large igneous province, southwestern China andnorthern Vietnam. Lithos 119, 75–90.

Herzberg, C., Asimow, P.D., 2008. Petrology of some oceanic island basalts:PRIMELT2.XLS software for primary magma calculation. Geochemistry,Geophysics, Geosystems 9. http://dx.doi.org/10.1029/2008GC002057.

Higgins, J.B., Ribbe, P.H., 1976. The crystal chemistry and space groups of naturaland synthetic titanites. American Mineralogist 61, 878–888.

Jerram, D.A., Widdowson, M., 2005. The anatomy of Continental Flood BasaltProvinces: geological constraints on the processes and products of floodvolcanism. Lithos 79, 385–405.

Keppler, H., 1993. Influence of fluorine on the enrichment of high field strengthtrace elements in granitic rocks. Contributions to Mineralogy and Petrology 114,479–488.

King, P.L., Hervig, R.L., Holloway, J.R., Delaney, J.S., Dyar, M.D., 2000. Partitioning ofFe3+/Fetotal between amphibole and basanitic melt as a function of oxygenfugacity. Earth and Planetary Science Letters 178, 97–112.

Kress, V.C., Carmichael, I.S.E., 1991. The compressibility of silicate liquidscontaining Fe2O3 and the effect of composition, temperature, oxygenfugacity and pressure on their redox states. Contributions to Mineralogyand Petrology 108, 82–92.

Leake, B.E., Woolley, A.R., Arps, C.E.S., Birch, W.D., Burke, E.A.J., Ferraris, G., Grice,J.D., Hawthorne, F.C., Kisch, H.J., Krivovichev, V.G., Schumacher, J.C., Stephenson,N.C.N., Whittaker, E.J.W., 2004. Nomenclature of amphiboles: additions andrevisions to the International Mineralogical Association’s amphibolenomenclature. European Journal of Mineralogy 16, 191–196.

Lee, C.-T.A., Leeman, W.P., Canil, D., Li, Z.-X., 2005. A similar V/Sc systematics inMORB and arc basalts: implications for the oxygen fugacities of their mantlesource regions. Journal of Petrology 46, 2313–2336.

Lee, C.-Y., Luffi, P., Le Roux, V., Dasgupta, R., Albarede, F., Leeman, W., 2010. Theredox state of arc mantle using Zn/Fe systematics. Nature 468, 681–685.

J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40 39

Author's personal copy

Lindsley, D.H., 1971. Synthesis and preliminary results on the stability ofaenigmatite (Na2Fe5TiSi6O20). Carnegie Institute of Washington, AnnualReport 1969–70, 188–190.

Luo, Z., Xu, Y., He, B., Shi, Y., Huang, X., 2007. Geochronologic and petrochemicalevidence for the genetic link between the Maomaogou nepheline syenites andthe Emeishan large igneous province. Chinese Science Bulletin 52, 949–958.

Manning, D.A.C., 1981. The effect of fluorine on liquidus phase relationships in thesystem Qz-Ab-Or with excess water at 1 kb. Contributions to Mineralogy andPetrology 76, 206–215.

Mathez, E.A., 1984. Influence of degassing on oxidation states of basaltic magmas.Nature 310, 371–375.

Miller, C.F., McDowell, S.M., Mapes, R.W., 2003. Hot and cold granites? Implicationsof zircon saturation temperatures and preservation of inheritance. Geology 31,529–532.

Mitchell, R.H., 1990. A review of the compositional variation of amphiboles inalkaline plutonic complexes. Lithos 26, 135–156.

Morimoto, N., Fabries, J., Ferguson, A.K., Ginzburg, I.V., Ross, M., Seifert, F.A.,Zussman, J., Aoki, K., Gottardi, G., 1988. Nomenclature of pyroxenes. Mineralogyand Petrology 39, 55–76.

O’Neill, H.St.C., Pownceby, M.I., Wall, V.J., 1989. Activity-composition relations inFeTiO3–MnTiO– ilmenite solid solutions from EMF measurements at 1050–1300 K. Contributions to Mineralogy and Petrology 103, 216–222.

Pang, K.-N., Zhou, M.-F., Lindsley, D., Zhao, D., Malpas, J., 2008. Origin of Fe–Ti oxideores in mafic intrusions: evidence from the Panzhihua intrusion, SW China.Journal of Petrology 49, 295–313.

Pang, K.-N., Zhou, M.-F., Qi, L., Shellnutt, G., Wang, C.Y., Zhao, D., 2010. Flood basalt-related Fe–Ti oxide deposits in the Emeishan large igneous province, SW China.Lithos 119, 123–136.

Pearce, J.A., Cann, J.R., 1973. Tectonic setting of basic volcanic rocks determinedusing trace element analyses. Earth and Planetary Science Letters 19, 290–300.

Ribbe, P.H., 1980. Titanite. Reviews in Mineralogy 5, 137–154.Sahama, Th.G., 1946. On the chemistry of the mineral titanite. Bulletin de la

Commission Geologique de Finlande 24, 88–120.Scaillet, B., Macdonald, R., 2001. Phase relations of peralkaline silicic magmas and

petrogenetic implications. Journal of Petrology 42, 825–845.Scaillet, B., Macdonald, R., 2003. Experimental constraints on the relationships

between peralkaline rhyolites of the Kenya rift valley. Journal of Petrology 44,1867–1894.

Shellnutt, J.G., Iizuka, Y., 2011. Mineralogy from three peralkaline granitic plutons ofthe Late Permian Emeishan large igneous province (SW China): evidence forcontrasting magmatic conditions of A-type granitoids. European Journal ofMineralogy 23, 45–61.

Shellnutt, J.G., Jahn, B.-M., 2010. Formation of the Late Permian Panzhihua plutonic-hypabyssal-volcanic igneous complex: implications for the genesis of Fe–Tioxide deposits and A-type granites of SW China. Earth and Planetary ScienceLetters 90, 509–519.

Shellnutt, J.G., Zhou, M.-F., 2007. Permian peralkaline, peraluminous andmetaluminous A-type granites in the Panxi district, SW China: theirrelationship to the Emeishan mantle plume. Chemical Geology 242, 286–316.

Shellnutt, J.G., Zhou, M.-F., 2008. Permian, rifting related fayalite syenite in thePanxi region, SW China. Lithos 101, 54–73.

Shellnutt, J.G., Zhou, M.-F., Zellmer, G.F., 2009a. The Permian Baima IgneousComplex (SW China): the role of Fe–Ti oxide crystallization in the formation ofA-type granitoids with implication for the Daly gap. Chemical Geology 259,204–217.

Shellnutt, J.G., Wang, C.Y., Zhou, M.-F., Yang, Y., 2009b. Zircon Lu-Hf isotopiccompositions of A-type granites of the Emeishan large igneous province (SWChina): evidence for an enriched mantle source. Journal of Asian Earth Science35, 45–55.

Shellnutt, J.G., Wang, K.-L., Zellmer, G.F., Iizuka, Y., Jahn, B.-M., Pang, K.-N., Qi, L.,Zhou, M.-F., 2011a. Three Fe–Ti oxide ore-bearing gabbro-granitoid complexesin the Panxi region of the Emeishan large igneous province, SW China. AmericanJournal of Science 311, 773–812.

Shellnutt, J.G., Jahn, B.-M., Zhou, M.-F., 2011b. Crustal-derived granites in thePanzhihua region, SW China: implications for felsic magmatism in theEmeishan Large Igneous province. Lithos, 145–157.

Shellnutt, J.G., Denyszyn, S., Mundil, R., 2012. Precise age determination of maficand felsic intrusive rocks from the Permian Emeishan large igneous province(SW China). Gondwana Research. http://dx.doi.org/10.1016/j.gr.2011.10.009.

Sheth, H.C., 2007. ‘Large igneous provinces (LIPs)’: definition, recommendedterminology, and a hierarchial classification. Earth-Science Reviews 85, 117–124.

Smith, P.M., Asimow, P.D., 2005. Adiabat_1ph: a new public front-end to the MELTS,pMELTS, and pHMELTS models. Geochemistry, Geophysics, Geosystems 6.http://dx.doi.org/10.1029/2004GC000816.

Song, X.Y., Zhou, M.-F., Hou, Z.Q., Cao, Z.M., Wang, Y.L., Li, Y., 2001. Geochemicalconstraints on the mantle source of the upper Permian Emeishan continentalflood basalts, southwestern China. International Geology Review 43, 213–225.

Song, X.-Y., Zhou, M.-F., Keays, R.R., Cao, Z.-M., Sun, M., Qi, L., 2006. Geochemistry ofthe Emeishan flood basalts at Yangliuping, Sichuan, SW China: implications forsulfide segregation. Contributions to Mineralogy and Petrology 152, 53–74.

Sun, S.S., McDonough, W.F., 1989. Chemical and isotopic systematics of oceanicbasalts: implications for mantle composition and processes. In: Saunders, A.D.,Norry, M.J. (Eds.), Magmatism in the Ocean Basins, vol. 42. Geological Society ofLondon Special Publication, pp. 313–435.

Takagi, T., 2004. Origin of magnetite and ilmenite-series granitic rocks in the Japanarc. American Journal of Science 304, 169–202.

Taylor, R.P., Fallick, A.E., 1997. The evolution of fluorine-rich felsic magmas: sourcedichotomy, magmatic convergence, and the origins of topaz granite. Terra Nova9, 105–108.

Wang, C.Y., Zhou, M.-F., Zhao, D., 2008. Fe–Ti–Cr oxides from the Permian Xinjiemafic-ultramafic layered intrusion in the Emeishan large igneous province, SWChina: crystallization from Fe- and Ti-rich basaltic magmas. Lithos 102, 198–217.

Watson, E.B., Harrison, T.M., 1983. Zircon saturation revisited: temperature andcomposition effects in a variety of crustal magma types. Earth and PlanetaryScience Letters 64, 295–304.

Weill, D.F., Drake, M.J., 1973. Europium anomaly in plagioclase feldspar:experimental results and semiquantitative model. Science 180, 1059–1060.

White, J.C., Ren, M., Parker, D.F., 2005. Variation in mineralogy, temperature, andoxygen fugacity in a suite of strongly peralkaline lavas and tuffs, Pantelleria,Italy. The Canadian Mineralogist 43, 1331–1347.

Wones, D.R., 1989. Significance of the assemblage titanite + magnetite + quartz ingranitic rocks. American Mineralogist 74, 744–749.

Xiao, L., Xu, Y.G., Mei, H.J., Zheng, Y.F., He, B., Pirajno, F., 2004. Distinct mantlesources of low-Ti and high-Ti basalts from the western Emeishan large igneousprovince, SW China: implications for plume–lithosphere interaction. Earth andPlanetary Science Letters 228, 525–546.

Xirouchakis, D., Lindsley, D.H., 1998. Equilibria among titanite, hedenbergite,fayalite, quartz, ilmenite, and magnetite: experiments and internally consistentthermodynamic data for titanite. American Mineralogist 83, 712–725.

Xu, Y., Chung, S.L., Jahn, B.M., Wu, G., 2001. Petrologic and geochemical constraintson the petrogenesis of Permian–Triassic Emeishan flood basalts insouthwestern China. Lithos 58, 145–168.

Xu, Y.G., He, B., Chung, S.L., Menzies, M.A., Frey, F.A., 2004. Geologic, geochemical,and geophysical consequences of plume involvement in the Emeishan flood-basalt province. Geology 32, 917–920.

Xu, Y.-G., Luo, Z.-Y., Huang, X.-L., He, B., Xiao, Xie, L.-W., Shi, Y.-R., 2008. Zircon U–Pband Hf isotope constraints on crustal melting associated with the Emeishanmantle plume. Geochimica et Cosmochimica Acta 72, 3084–3104.

Xu, Y.-G., Chung, S.-L., Shao, H., He, B., 2010. Silicic magmas form the Emeishan largeigneous province, southwest China: petrogenesis and their link with the end-Guadalupian biological crisis. Lithos 119, 47–60.

Yavuz, F., 2007. WinAmphcal: a Windows program for the IMA-04 amphiboleclassification. Geochemistry, Geophysics, Geosystems 8. http://dx.doi.org/10.1029/2006GC001391.

Zhong, H., Zhu, W.G., Song, X.Y., He, D.F., 2007. SHRIMP U–Pb zircon geochronology,geochemistry, and Nd-Sr isotopic study of contrasting granites in the Emeishanlarge igneous province, SW China. Chemical Geology 236, 112–137.

Zhong, H., Zhu, W.-G., Hu, R.-Z., Xie, L.-W., He, D.-F., Liu, F., Chu, Z.-Y., 2009. ZirconU–Pb age and Sr–Nd–Hf isotope geochemistry of the Panzhihua A-type syeniticintrusion in the Emeishan large igneous province, southwest China andimplications for growth of juvenile crust. Lithos 110, 109–128.

Zhou, M.-F., Arndt, N.T., Malpas, J., Wang, C.Y., Kennedy, A.K., 2008. Two magmaseries and associated ore deposit types in the Permian Emeishan large igneousprovince, SW China. Lithos 103, 352–368.

40 J.G. Shellnutt, Y. Iizuka / Journal of Asian Earth Sciences 54–55 (2012) 31–40