Intermediate Sulfidation Epithermal Pb-Zn-Cu (±Ag-Au ...

JOURNAL GEOLOGICAL SOCIETY OF INDIAVol.80, October 2012, pp.563-578

0016-7622/2012-80-4-563/$ 1.00 © GEOL. SOC. INDIA

Intermediate Sulfidation Epithermal Pb-Zn-Cu (±Ag-Au)Mineralization at Cheshmeh Hafez Deposit,

Semnan Province, Iran

BEHZAD MEHRABI and MAJID GHASEMI SIANI

Department of Geology, Faculty of science, Tarbiat Moallem University, Tehran, IranEmail: [email protected]

Abstract: The Cheshmeh Hafez epithermal base metal deposit is located in Troud-Chah Shirin mountain range in theAlborz magmatic belt of northern Iran. In this area, the Eocene volcanism and associated mineralization are controlledby NW-SE trending Anjilo and Troud major faults. Geological units are composed of porphyritic andesite, andesiticbasalt, dacite, rhyodacite, trachyandesite and basalt, which are typically high-K igneous rocks transitional to shoshonites.Alteration in Cheshmeh Hafez area comprise of propylilitization, sericitization, argillization and silicification.Mineralization consists of three stages. Stage 1, quartz, carbonate with early pyrite I and chalcopyrite assemblages.Stage 2, the main stage of sulfide deposition, comprises early euhedral galena I followed by galena II and sphalerite,then galena III, chalcopyrite, tetrahedrite, pyrite II, bornite and digenite. Stage 3 involves the deposition of quartz andcalcite barren veins with minor pyrite. The average assays from 12 channel samples of Cheshmeh Hafez veins are 0.15g/t Au, 3.23 g/t Ag, 4.47 wt % Pb, 2.64 wt % Cu, and 1.73 wt % Zn. Fluid inclusion homogenization temperatures (Th)in quartz fall within the range of 140º-280ºC with salinities ranging from 4.7 to 18 wt. % NaCl equivalent. Comparisonof Th versus ice melting (Tmice) values indicates fluid dilution.

Keywords: Pb-Cu-Zn Mineralization, Cheshmeh Hafez deposit, Fluid inclusion, Alteration, Geochemistry, Iran.

INTRODUCTION

The Cheshmeh Hafez poly-metal deposit is located inthe Troud-Chah Shirin mountain range of the Alborzmagmatic belt (AMB) (Fig. 1a) (Aghanabati, 2003). Theregional geochemical exploration project from 1990 to 1996by Geological Survey of Iran (1995) covered 42,000 km2 innorth-central Iran, producing 26 maps at a scale 1:100,000,including the Troud-Chah Shirin mountain range (1995).Based on the survey, five districts were recommended fordetailed Pb-Zn-Cu-An-Ag prospecting, and CheshmehHafez district was one of these promising districts. Thoughthe mineralization in two other districts (Gandy andAbolhassani) described previously by Shamanian (2003),and classified as poly-metal intermediate sulfidationepithermal system based on wall-rock alteration,geochemistry and vein alteration assemblages, but no workhas been undertaken at the Cheshmeh Hafez deposit.Therefore we focused on the Cheshmeh Hafez deposit. TheCheshmeh Hafez deposit, is situated approximately 22 km(14 miles) northeast of the Moaleman town and ~ 300 kmeast of Tehran (Fig.1b). This paper is mainly focused on theCheshmeh Hafez deposit, which is located at 35º25'N and

54º50' E in the area. The Cheshmeh Hafez district contain asmall abandoned (Pb-Cu-Zn) mine. Mining in CheshmehHafez district commenced in 1949 and continued until theearly 1967. Modern exploration program at the CheshmehHafez district has been conducted by the Iranian mineralresearch and application Co. (IMRA), through a projectentitled ‘The Geology and Geochemistry of the CheshmehHafez Pb-Zn-Cu-Ag-Au mineralization from 2002 to 2008.The goal of the present investigation is to propose a geneticmodel for polymetallic mineralization in the CheshmehHafez area, based on geology, alteration, geochemistry andfluid inclusion data. The enhancement of criteria forexploration of epithermal deposits in the Troud-Chah Shirinmountain range is an additional aim of this study.

SAMPLING AND ANALYTICAL METHODS

In the course of exploration program for Pb-Cu-Zn inthe Cheshmeh Hafez district, 280 samples from mineralizedveins and altered host rock exposures were collected forgeochemical survey. 150 samples were also taken from tendiamond drill holes (total 930 m). Samples were analyzed

JOUR.GEOL.SOC.INDIA, VOL.80, OCT. 2012

564 BEHZAD MEHRABI AND MAJID GHASEMI SIANI

for major and selected trace elements by AAS (Varian, spectrAA, 55B) and ICP-MS techniques at Zar Kavan Co. of Iran,and ACME Lab. of Canada (Group 1T-MS), respectively.Samples for mineralogical studies were taken from host,altered and mineralized rocks. Ninety-six polished thin-sections were prepared to determine the parageneticrelationships among the ore minerals and to characterizethe hydrothermal alteration assemblages. Mineral sampleswere analysed by optical microscopy (Zeiss, Axioplan2),X-Ray diffraction (XRD, Philips Expert-Pro), X-Rayfluorescence (WD-XRF, Philips PW2404) and scanningelectron microscopy (SEM-EDS, Tescan-VEGA).Microthermometric determinations were carried on 10doubly polished thin-sections from quartz veins using aLinkam, THM 600 freezing-heating stage in the TarbiatMoallem University. The precision of the temperaturemeasurements was less than ±1ºC for heating and ±0.3 ºCfor freezing.

REGIONAL GEOLOGY

The Alborz magmatic belt is situated in northern Iranwith an E-W orientation, and subdivided into eastern andwestern parts (Fig. 1a). The western part consists of andesiticto dacitic lava and granitoid bodies with calc-alkaline affinity(Moayyed, 2001, Azizi and Jahangiri, 2008), whereas theeastern part consists of mafic and acidic tuffs and mafic lava

with an alkaline to shoshonitic affinity (Azizi and Jahangiri,2008). The Troud-Chah Shirin range lies in the easternportion of the Alborz magmatic belt (AMB), and forms anuplifted block bounded by the Troud fault in the south andthe Anjilo fault in the north (Fig.1b). Distribution of theTertiary igneous rocks shows that the western portion ofAMB merges with another Tertiary magmatic belt (Fig.1a),the Urmieh-Dokhtar zone (UDZ), which runs parallel to themain northwest-trending Zagros thrust (MZT) (Stocklin,1968). The Troud-Chah Shirin range located at AMB andis characterized by thick accumulations of early to middleEocene submarine green tuffs (equivalent to the KarajFormation), followed by the late Eocene, to possibly earlyOligocene, submarine to subaerial lava flows which locallyinclude nepheline-normative and shoshonitic rocks. Silica-saturated volcanic rocks are exposed locally.

The Troud-Chah Shirin volcano-plutonic chain, whichextends over 100 km along a NE-SW trend, hosts manymineral deposits, particularly epithermal base metal veins.In addition to Cheshmeh Hafez (Cu-Pb-Zn), otheroccurrences (Fig. 1b) include Abolhassani (Pb-Zn-Ag-Au),Gandy (Au-Ag-Pb-Zn), Chalo (Cu-Au) and Chah Messi(Cu). Other types of deposits in this range include placergold (Baghu-Darestan) and MVT type deposits (Khanjar).The Baghu-Darestan gold placer is located at 10 kmnorthwest of the district, and it is probably the product ofweathering of nearby quartz sulfide veins hosted by andesitic

Fig.1. (a) Location map of two main Tertiary volcanic belts of Iran: The NW- trending Urmieh- Dokhtar zone (UDZ) which runs parallelto the main Zagros Thrust (MZT), and the Alborz magmatic belt (AMB) in northern Iran, that subdivided to E. Alborz and W.Alborz. (b) The major exposed rock unit of the Troud (T) includes the Paleogene volcano- plutonic complex, and major epithermaland other types of mineralization occurrences in the Troud-Chah Shirin mountain range. CH, Cheshmeh Hafez (Pb-Cu-Zn); GA,Gandy (Au-Ag-Pb-Zn); AB, Abolhassani (Pb-Zn-Ag-Au); CL, Chalo (Cu-Au); CM, Cah Messi (Cu); BG, Baghu-Darestan (Au)and KH, Khanjar (Pb-Zn) deposits.


INTERMEDIATE SULFIDATION EPITHERMAL Pb-Zn-Cu MINERALIZATION, SEMNAN PROVINCE, IRAN 565

volcanic rocks. Khanjar deposit is a Pb-Zn deposit hostedby carbonate rocks in the west of the district (Fig.1b). TheTroud-Chah Shirin range consists mainly of igneous rocksof Tertiary age, although there are also scattered outcropsof metamorphosed Paleozoic and Mesozoic rocks. Peakmagmatic activity occurred from the middle to possibly lateEocene and has been divided into three stages, fromoldest to youngest (Hushmandzadeh et al. 1978) include:(1) explosive volcanic activity represented by rhyolitic torhyodacitic tuffs and locally andesitic lava flows, withsubordinate marls, tuffaceous marlstones, and sandstones;

(2) lava flows and pyroclastic rocks of andesite,trachyandesite and basaltic andesite composition and;(3) subordinate dacitic-rhyodacitic rocks and hypabyssalintrusive rocks.

DEPOSIT GEOLOGY

Host Rocks and Geological Setting

Outcrops in the Cheshmeh Hafez deposit from the oldestto youngest comprises of (1) pyroclastic rocks include thin-bedded siltstones, tuffaceous sandstone, conglomerate and

Fig.2. Geological maps of the Cheshmeh Hafez and Ghardane Toto districts.



marl of lower Eocene age; (2) andesitic, basaltic andesiteand trachy-andesitic flows of middle to late Eocene, and(3) rhyo-dacitic and dacitic domes are the youngest rocksin the district, which are Oligocene or younger in age(Fig. 2). Mineralization in the Cheshmeh Hafez deposit ishosted by andesite, trachy-andesite, rhyo-dacite and dacite.

Whole-rock major element analyses of 25 samples fromvolcanic and subvolcanic rocks were analyzed by PhilipsPW2404WD-XRF at the Tehran Tarbiat Moallem Universityin order to depict theh petrochemical characteristics andtectonic setting. The trace and rare earth elements analysiswere carried out in the ACME laboratories, Vancouver,Canada (Tables 1 and 2) using ICP-MS (Group 1T-MS)technique. The rocks (Figs. 3 and 4) are characterized byhigh K2O contents (up to 5.8 wt.%), high average K2O/Na2O

ratios (0.7), and high average Ce/Yb ratios (20.3), whichare typical of high-K igneous rocks of transitional toshoshonitic series (Muller et al. 1992; Pearce, 1982). Therelatively high CaO concentrations of the rocks (up to 12.1wt.%) reflect their derivation from fertile upper mantlematerial (Schmidt et al. 2000) that was metasomaticallyenriched during subduction processes (Kennedy et al. 1990).Spidergram for volcanic rocks from Cheshmeh Hafez(Fig. 5) shows negative anomaly for Nb, Ti and Zr elements,and high concentrations of large ion litophile elements andlow concentration of high field strength elements, typicalof arc igneous rocks (Muller et al. 1992; Pearce and Peate,1995). These data indicate that the investigated volcanicrocks were developed in a volcanic-arc environment, whichare consistent with the other studies on the tectonic settingof the Alborz magmatic belt (Alavi, 1996; Hassanzadehet al. 2002).

Structure

Four fault systems were identified in the CheshmehHafez district based on field observation and Rose diagramschemas (Fig. 6a). Most of the poly-metal veins depositedin the district are mainly bounded by N-S faults and fracturessystem (60º SW) (Fig. 6b), while the Gardaneh Toto veinsin the northern part are mainly bounded by NE-SW faultsystems. The Other fault system is NW-SE trending set whichis insignificant (Fig. 6a). Brown and white barren carbonateveins were mainly confined to E-W fault system. This faultsystem is younger than the others. Structural patterns aremainly controlled by two principal strike-slips faults, theAnjilo in the north and the Troud in the south, both withnortheast trend.

Fig.3. Total alkali vs. SiO2

biaxial plot (TAS plot) of selectedsamples ranging from basalt through andesitic totrachyandesite (Wilson, 1989).

Fig.4. K2O vs. SiO

2 biaxial plot, (Peccerillo and Taylor, 1997), is

illustrating the potassic composition of investigatedsamples.

Fig.5. Primitive mantle-normalized spidergram for volcanic rocksfrom the Cheshmeh Hafez deposit (normalization afterMcDonough and Sun, (1995). The patterns with apparentlows at Nb, Ti, and Zr, are typical of subduction zone arcmagmas.



Table.2. Sample analyses from the Cheshmeh Hafez district. Major oxides were analyzed by XRF at the Tarbiat Moallem University (Iran), and other elements were analyzed byICP-MS at ACME Labs (Canada)

Sample Detection 87CH-1 87CH-2 87CH-3 87CH-4 87CH-5 87CH-6 87CH-7 87CH-8 87CH-9 87CH-10 87CH-11 87CH-12 87CH-13 87CH-14limit andesite basalt andesite andesite andesite andesite basalt basaltic- andesite basalt basaltic- trachy- trachy- basalt

Andesite Andesite Andesite Andesite

SiO2 0.05% 50.50 49.26 51.60 51.60 56.44 54.30 50.91 50.72 50.92 51.24 47.50 53.44 54.44 47.77(wt %)TiO2 0.05% 0.90 0.78 0.80 1.10 0.77 0.60 0.80 10.70 0.80 1.59 0.90 0.72 0.70 0.60Al2O3 0.03% 16.30 15.45 16.96 16.60 14.22 13.70 16.30 13.82 14.15 11.50 14.50 14.41 15.40 11.93Fe2O3

(t) 0.03% 8.00 11.40 8.10 7.90 9.29 5.70 12.00 8.45 11.27 11.59 8.30 9.09 9.00 10.73MnO 0.03 % 0.70 0.20 0.40 0.30 0.16 0.10 0.13 0.24 0.14 0.16 0.20 0.14 0.15 0.19MgO 0.03% 11.20 10.10 2.10 1.30 4.00 1.10 7.04 6.11 6.73 3.75 7.60 7.80 6.20 5.39CaO 0.02% 4.32 5.00 8.10 4.50 6.00 8.10 5.10 4.88 5.87 11.18 8.30 8.18 5.80 12.10Na2O 0.02% 1.80 1.50 2.00 0.40 2.50 2.40 3.50 1.46 2.65 2.61 1.90 1.33 2.10 1.07K2O 0.02% 3.03 1.10 5.70 5.80 2.70 3.40 1.10 2.46 1.30 0.19 1.90 1.00 1.10 0.95P2O5 0.02% 0.70 0.14 0.80 0.60 0.12 0.30 0.19 0.25 0.21 0.24 0.30 0.15 0.17 0.24LOI 3.50 5.20 2.20 8.50 2.96 7.80 3.77 2.25 5.60 5.60 7.30 3.22 3.50 8.40Total 100.95 100.13 98.76 98.60 99.16 100.9 100.84 101.34 97.03 99.65 98.70 99.48 98.56 99.37

PpmAu 0.1 ppm <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 0.30 <0.10 <0.10 <0.10 <0.10 <0.10Ag 20.00 ppb 5458.00 1811.00 85.00 2906.00 19.50 24.40 20.80 32.00 410.00 14.20 18.00 22.20 11.40 10.10As 0.2 ppm 3.40 15.10 6.40 106.60 3.10 4.00 26.70 15.20 16.90 8.20 11.80 12.70 2.70 74.20Ba 1.0 ppm 2.71 23.00 441.00 622.00 515.00 58.00 492.00 932.00 94.00 409.00 432.00 837.00 1204.00 19.00Bi 0.04 ppm 0.33 4.23 0.06 0.08 0.04 5.68 <0.04 0.07 0.41 0.18 0.03 0.13 0.10 0.37Co 0.2 ppm 18.90 10.80 14.80 26.50 29.60 18.40 20.80 20.00 16.10 20.40 22.00 15.80 6.90 2.80Cr 1.0 ppm 31.00 14.00 44.00 44.00 45.00 14.00 29.00 27.00 14.00 39.00 28.00 27.00 17.00 11.00Ni 0.1 ppm 12.80 9.40 15.80 19.50 24.40 20.80 32.00 14.20 8.90 18.00 22.20 11.40 10.10 5.40Nb 0.04 ppm 4.57 0.74 7.09 5.99 6.56 1.27 4.11 4.32 0.55 7.00 6.45 6.90 2.97 1.44Rb 0.1 ppm 69.50 12.30 90.40 100.50 50.50 18.10 108.90 148.40 9.90 71.60 62.90 81.50 102.30 21.90Sb 0.02 ppm 1.60 16.05 0.92 6.39 0.97 3.36 4.21 1.75 15.12 1.02 0.94 1.91 1.43 0.48Sc 0.1 ppm 13.90 2.00 19.00 14.40 25.50 6.90 13.60 14.80 1.80 17.80 10.90 11.20 13.40 4.90Sn 0.1 ppm 0.70 0.60 1.10 1.20 1.20 0.40 0.80 0.80 0.40 1.00 1.00 1.30 0.60 0.10Sr 1.0 ppm 142.00 38.00 334.00 80.00 766.00 29.00 202.00 204.00 55.00 406.00 448.00 143.00 334.00 215.00Th 0.1 ppm 3.80 0.50 4.20 2.60 5.00 0.80 1.60 3.30 0.40 4.80 4.10 4.30 1.90 0.70U 0.1 ppm 1.10 0.50 1.00 1.80 1.50 0.50 0.70 1.10 0.60 1.30 1.10 1.20 0.60 0.50Zn 0.2 ppm 158.60 559.80 102.50 >10000 90.10 195.70 441.30 197.70 65.00 107.30 134.40 180.60 169.70 16.80Pb 0.02 ppm 36.01 7320.00 18.34 >10000 36.71 13.75 273.00 85.90 280.70 32.44 47.67 21.09 40.86 34.34V 1.0 ppm 124.00 30.00 222.00 195.00 274.00 52.00 185.00 160.00 35.00 215.00 150.00 119.00 137.00 68.00Y 0.1 ppm 20.00 2.60 16.20 5.90 18.70 3.00 8.03 12.70 2.70 18.00 14.30 11.80 13.10 22.40Cu 0.02 ppm 4504.00 2496.00 103.50 746.30 39.98 >10000 49.86 121.60 772.10 528.00 12.58 1319.00 77.22 200.70Mn 2.0 ppm 3722.00 897.00 1737.00 381.00 1001.00 318.00 2000.00 3375.00 2265.00 1003.00 1111.00 1731.00 6380.00 6712.00Fe% 0.02 % 5.69 2.97 4.60 4.67 5.90 8.94 5.51 5.03 4.11 4.86 4.68 5.16 3.58 4.11Mg% 0.02 % 2.71 0.05 1.13 1.03 1.89 0.53 0.55 2.24 0.05 2.37 1.10 0.89 0.73 0.20

REELa 0.1 ppm 16.00 2.00 14.07 9.06 19.30 11.10 7.40 14.20 1.80 17.50 15.70 12.10 29.30 20.00Ce 0.02 ppm 34.30 4.16 33.76 17.57 38.52 16.14 17.41 27.19 4.68 37.40 31.37 27.86 46.75 73.33Nd 0.1 ppm 25.50 2.80 22.00 12.80 22.50 5.90 10.80 16.50 3.60 20.50 16.30 15.30 23.00 30.60Sm 0.1 ppm 5.50 0.50 4.40 2.60 4.40 1.10 2.40 2.80 0.80 4.10 3.01 2.90 3.70 7.30Eu 0.1 ppm 1.80 0.20 1.20 0.50 1.30 0.30 0.60 0.80 0.30 1.00 0.80 0.70 1.60 2.40Hf 0.02 ppm 1.95 0.28 2.45 1.48 3.15 0.38 1.51 2.08 0.11 2.70 2.98 2.36 1.12 0.11Yb 0.1 ppm 1.60 0.20 1.70 0.80 1.90 0.30 0.90 1.40 0.20 1.60 1.40 1.10 1.00 0.90Lu 0.1 ppm 0.20 <0.10 0.20 0.10 0.30 <0.10 0.10 0.20 <0.10 0.30 0.20 0.20 0.20 0.10Er 0.1 ppm 1.60 0.30 1.70 0.80 2.20 0.30 1.00 1.40 0.20 1.80 1.50 1.20 1.10 1.30

Table.1. Selected analysis from the Cheshmeh Hafez veins (AAS method in Zar Kavan. CO)

Samples Detection Ch-tr-17 Ch-tr-18 Ch-tr-84 Ch-74 Ch-tr-10 Ch-87-po Ch-87 Ch-88 Ch-tr-50 Ch-tr-80 Ch-tu-95 Ch-99Limit

Pb (%) 0.01% 13.00 4.91 10.00 0.91 8.00 11.70 2.97 0.04 0.41 0.98 0.88 0.25

Cu (%) 0.01% 0.98 2.00 17.16 3.13 0.95 3.30 0.97 0.80 0.02 0.02 1.00 1.40

Zn (%) 0.01% 0.62 1.23 4.13 1.51 4.22 3.56 4.42 0.07 0.10 0.35 0.26 0.39

Au (ppm) 0.05ppm 0.06 0.33 0.70 0.16 0.10 0.09 0.03 0.03 .002 .008 0.04 0.28

Ag (ppm) 0.05ppm 8.30 8.10 3.50 0.39 0.80 4.80 2.00 0.90 0.95 0.37 0.23 8.50

Mo (ppm) 0.05ppm 20.70 14.30 14.90 17.80 0.50 1.00 8.89 1.40 2.80 14.90 0.86 19.00

Cd (ppm) 0.05ppm 153.00 17.00 16.50 3.60 1.90 5.00 64.00 5.00 2.40 2.20 12.00 13.50



Wall Rock Alteration

Hydrothermal alteration is intense adjacent to veins andis 2 m wide, but variable intensity of hydrothermal alterationis noticed in scattered outcrops. Hydrothermal alterationincludes silicification, sericitization, argillization andpropylitization. The propylitic alteration occupies the outermost part of the deposit, whereas the silicic alteration isfound in the inner part of the deposit and is commonlyassociated with ore minerals. Gemmell (2006) argued thatin the mafic-hosted systems the distal propylitic alterationis well developed compare to the felsic-host systems. In theCheshmeh Hafez district, propylitic alteration is morewidespread than other types of alteration. Propyliticalteration consists of chlorite, epidote and minor albite(Fig. 7c). Silicification in Cheshmeh Hafez ore body is inthe form of pervasive replacement and veins and veinlets.Silicified rock is characterized by equigranular micro-crystalline quartz, sericite, illite, hematite and sulfideminerals (Fig.7a). Sericitic alteration usually consists ofsericite, quartz (Fig.7b) and ankerite which was identifiedby X-ray diffraction analysis. Plagioclase phenocrysts arealmost completely replaced by fine-grained carbonate andwhite mica. Argillic alteration zones, next to quartz-basemetal veins are dominated by kaolinite, and chlorite withminor mixed layer illite/smectite minerals (Fig. 7a and d).

Ore Bodies and Ore Mineralogy

The Cheshmeh Hafez Pb-Zn-Cu-Ag-Au vein deposit ishosted by the Eocene andesitic to dacitic volcanic rockswith open space filling and replacement textures (Fig. 8a).Mineralized zones were studied in two old tunnels, namelyCheshmeh Hafez and Gardaneh Toto, where the mineralizedarea are exposed. The Cheshmeh Hafez vein have strike

and dip of N10° to 20° E and 50° to 60° SW respectively,with 30 to 150 m length. Thickness ranges from 0.5 to7 m. The Gardaneh Toto vein has strike and dip of N30° to45° E and 30° to 40° SW respectively, with 20 to 120 mlength. The veins consist mainly of quartz, calcite andsulfides such as galena, sphalerite, pyrite, chalcopyrite, tetra-hedrite, bornite and digenite. Supergene minerals arechalcocite, covellite, cerussite, malachite and Fe-oxy-hydroxides

Ore and gangue mineral assemblages identified inCheshmeh Hafez deposit are typical of intermediate-sulfidation epithermal deposits including quartz, calcite,chalcopyrite, pyrite, sphalerite, galena, tetrahedrite, digenite,and bornite which are associated with illite and illite-smectitemixed-layer clays (e.g., Einaudi et al. 2003 and Kouzmonov,et al. 2009). Pyrite is one of the most common and earliest-formed sulfides in the Cheshmeh Hafez deposit. Pyrite Ioccurs as euhedral crystals accompanied with chalcopyritewithin early quartz-carbonate filled fractures in stage 1.Pyrite II occurs as subhedral to anhedral crystalsaccompanied with galena III and chalcopyrite (stage 2c).Galena is generally the second most abundant sulfide mineralin these veins. Galena I occurs as euhedral crystals in stage2a, and in most cases, galena II appears to have co-precipitated with sphalerite (stage 2b). Galena III filledfractures and co-precipitated with chalcopyrite, bornite,digenite and tetrahedrite. Sphalerite in Cheshmeh Hafez isvery Fe-poor (0.4 to 0.8 wt. % Fe or 0.6 to 1.1 FeS mol %).In some parts of the deposit chalcopyrite replaces pyritealong crystal boundaries and fractures. The chalcopyrite is,in turn, replaced by secondary chalcocite, covellite andgoethite. Minor bornite and digenite occurs at the edge ofchalcopyrite grains in some samples (stage 2c). Einaudi et

Fig.6. Rose diagrams for the fault/joint (a) and mineralized veins (b).



al, (2003) suggested, albeit with caution, that the FeS mol%content of sphalerite coexisting with pyrite or pyrrhotite atintermediate-sulfidation states should range from 0.2 to 1%.The FeS contents of sphalerite in intermediate-sulfidationepithermal Pb–Zn–Cu-Ag–Au deposits (Gandy andAbolhassani) in the Eocene arc of the Troud-Chah Shirinmountain range in northern Iran (near to Cheshmeh Hafezdeposit) ranged from 0.8 to 1.6 mol% (Shamanian et al.2003). The FeS contents of Cheshmeh Hafez depositsphalerite (0.6 to 1.1 mol% FeS) is comparable to those ofthe Troud-Chah Shirin intermediate-sulfidation epithermalPb–Zn–Cu-Ag–Au deposits (Gandy and Abolhassanideposits), and Sahinli and Tespih Dere intermediate-sulfidation epithermal Pb–Zn–Ag–Au deposits in Lapseki /Western Turkey (Yilmaz et al. 2010). The mineral

paragenesis of the vein mineralization can be divided intostage 1, stage 2 – main sulfide stage and stage 3 – supergenestage (Fig. 9). The stage 1 alteration is represented byepidote, chlorite (clinochlore), calcite and quartz with pyriteI and chalcopyrite. Main sulfide stage is characterized bydeposition of medium and coarse-grained quartz, initiallyeuhedral galena I (Fig. 8b) followed by galena II andsphalerite (Fig. 8e), and finally galena III, pyrite II,chalcopyrite, tetrahedrite, bornite and digenite weredeposited in main sulfide stage (Fig. 8f). The alterationassemblage accompanying main sulfide stage is muscovite/illite and montmorillonite whereas ankerite–dickite–kaolinite may have formed in the later part of main sulfidestage and/or during the supergene stage. Stage 3 involvesthe deposition of quartz and calcite barren veins with minor

Fig.7. (a) Plagioclase phenocrysts replaced by kaolinite, and chlorite in argillic alteration, and silicification alteration (si). (b) Plagioclasephenocrysts replaced by fine-grained carbonate and white mica due to sericitic alteration. (c) Propylitic alteration consists ofsericite (altered plagioclase) and chlorite (chl). (d) Pyroxene phenocrysts replaced by kaolinite, and chlorite. (pl, plagioclase;

py, pyroxene; chl, chlorite; si, silicification alteration; Ser, sericite).



Fig.8. Veins outcrop (a), Reflected light photomicrographs (b, c, d and f), and backscattered electron image (e) of quartz-sulfide veins.(a) Mineralized vein in andesitic host rocks. (b) Euhedral galena I (stage 2, a) which altered to cerussite from rim. c) Recrystalizedgalena II during later tectonic events exhibit moderately deformed arrays of triangular cleavage pits. (d) Fractured pyrite I inmineralized veins, as result of post mineralization deformation event. (e) Galena II and sphalerite of stage 2, b. (f) Galena III,pyrite II and chalcopyrite (stage 2, c). (Ga, galena; Sph, sphalerite; Qa, quartz; Py, pyrite; Cpy, chalcopyrite; Cer, cerussite)



pyrite. The supergene mineral assemblage consists ofchalcocite, covellite, cerussite, malachite and Fe-oxy-hydroxides.

Moderately deformed arrays of triangular cleavage pitsare commonly present within galena (Fig. 8c), suggestingthat galena has undergone some deformation withoutcomplete recrystallization during later tectonic events.Subsequently, the Cheshmeh Hafez mineral systemunderwent moderate deformation resulting in folding of thehost rock sequence, evident by faulting of some mineralized

veins, resulting in fracturing of pyrite (Fig. 8d) andchalcopyrite and deformation of galena.

GEOCHEMISTRY

Sampling of altered rocks in this study provides theopportunity to investigate possible systematic variations inprecious and base metals, REE, minor element and majoroxides in hydrothermal altered volcanic rocks that host theCheshmeh Hafez deposit. The element content of the hostrocks, and the ore veins were analyzed at ACME analyticallaboratories (Canada) by ICP-MS methods (Group 1T-MS).Data for all samples are presented in Table 1 and 2. Theaverage assay varies from 12 channel samples (present inTable 1) collected across the width (10-70 cm) of theCheshmeh Hafez and Gardaneh Toto veins are 0.15 g/t Au,3.23 g/t Ag, 4.47 wt % Pb, 2.64 wt% Cu, and 1.73 wt% Zn.Geochemical relationship between base metal and Au-Agelements from mineralized epithermal quartz veins arepresented in Table 3 and Fig.10.

In the Cheshmeh Hafez district, Pb correlates positivelywith Zn (r= 0.94), Cd (r= 0.88), and Cu (r= 0.59), and ascorrelates positively with Sb (r= 0.35). Geochemical zoningis partly developed along main ore veins. Along the axis ofthe veins Zn, Pb and Cu increase and Ag and Au decreasetowards the north. The highest Pb and Zn values werefound in samples from Gardaneh Toto in northern part, andhighest Cu and Au-Ag were found in samples fromCheshmeh Hafez veins in southern part. Geochemical

Table 3. Matrix of correlations between measured variable for Cheshmeh Hafez data

Au Ag Cu Pb Zn As Sb Cd Bi Mo Ba Rb Sr Co Sn Nb K2O SiO

2MgO CaO Na

2O La

La -0.30 -0.26 0.15 0.45 0.20 0.81 0.08 -0.17 0.05 0.02 0.02 0.95 0.35 0.84 0.80 0.71 0.94 -0.85 0.85 0.84 0.74

Na2O -0.23 -0.60 -0.22 -0.57 -0.80 -0.44 -0.21 -0.15 -0.05 -0.15 0.03 -0.22 0.27 -0.01 -0.36 0.08 -0.42 0.16 0.29 0.42

CaO -0.15 -0.56 -0.17 -0.50 -0.46 -0.02 -0.44 -0.17 -0.26 -0.14 0.31 -0.10 0.30 0.10 0.03 0.30 -0.36 0.18 -0.36

MgO -0.11 0.04 -0.16 0.02 -0.34 -0.23 0.61 -0.19 0.01 -0.12 -0.21 -0.02 0.16 -0.32 0.30 0.08 -0.42 -0.40

SiO2

0.25 -0.54 -0.13 -0.50 -0.22 -0.31 -0.42 -0.15 -0.13 -0.05 -0.29 0.07 0.30 -0.06 0.17 0.13 0.15

K2O -0.25 0.43 -0.02 0.09 0.32 -0.37 0.01 0.14 0.26 0.04 -0.01 0.08 -0.17 0.22 -0.05 0.01

Nb -0.31 -0.21 0.28 -0.13 -0.10 0.10 -0.24 -0.18 -0.75 0.03 0.37 0.09 0.41 0.44 0.40

Sn -0.31 0.04 -0.44 -0.04 0.21 0.15 -0.54 -0.18 -0.70 0.00 0.15 0.67 0.64 0.13

Co -0.33 0.26 0.04 0.16 0.13 0.05 0.08 -0.20 -0.28 0.01 0.68 -0.13 -0.30

Sr -0.10 -0.34 0.79 -0.45 -0.36 -0.19 -0.82 -0.02 -0.73 -0.04 -0.06 0.64

Rb -0.20 0.05 -0.49 -0.23 0.19 0.10 -0.64 -0.14 -0.53 0.07 -0.34

Ba -0.21 0.08 -0.13 0.41 0.13 0.22 0.29 0.11 -0.22 0.07

Mo -0.17 0.20 -0.05 0.11 0.20 0.09 -0.08 -0.06 0.05

Bi -0.05 0.28 0.53 0.18 0.09 -0.32 0.48 -0.03

Cd 0.15 0.33 0.78 0.88 0.75 0.17 0.15

Sb 0.22 0.30 0.47 0.76 0.42 0.38

As 0.10 0.13 0.17 0.56 0.57

Zn 0.13 -0.40 0.66 0.94

Pb 0.11 -0.38 0.59

Cu 0.10 -0.26

Ag 0.23

Au

Fig.9. Paragenetic sequence of sulfide and gangue minerals at

Cheshmeh Hafez deposit

Post ore/

Supergen

Stage 3

Stage 2 (Main sulfide stage)

a b c

Stage 1

Mineral

Quartz

Pyrite

Chalcopyrite

Galena

Sphalerite

Bornite

Tetrahedrite

Digenite

Calcite

Fe-oxy-hydroxides

Covellite

Chalcosite

Malachite

Cerussite



anomalies of wall rock around the veins in the CheshmehHafez were determined over an area of 1 km2. Allelements show a log normal distribution and indicateenrichment and Pb, Zn and Cu. Both linear and clusteranalysis, not reported here, show positive correlationbetween Zn and Ag and between Cu and Pb. Geochemicaldistribution of elements show good spatial correlationwith the distribution of exposed veins and alterationzones.

FLUID INCLUSIONS

Morphology and Petrography of Fluid Inclusions

Fluid inclusion studies were carried out on 10 doublypolished sections chosen from different veins at CheshmehHafez. Fluid inclusions in sphalerite crystals are very smalland are not suitable for study, whereas, quartz crystalcontains inclusions suitable for study. Based on the criteriaof (Rodder, 1984; Shepherd et al. 1985), morphology and

Fig.10. Log plot of concentrations of Pb-Zn, Zn-Cu, Pb-Cu, Ag-Zn, Ag-Pb, Ag-Cu in the Cheshmeh Hafez. Altered host rock samples

(Circles), and Mineralized vein samples (squares).



petrographic characteristics of the fluid inclusions wererecorded at room temperature. Primary, pseudosecondaryand secondary inclusions were identified which are mostlyaqueous liquid rich with no daughter minerals. Mostinclusions are two phase (L+V) at room temperature (Fig.11a). The size of fluid inclusions ranges from 5 to 25 µmand are elliptical, irregular, tabular and rod in shape (Figs.11c and d). Primary fluid inclusions occur in growth zonesparallel to crystal faces, as single inclusions or as isolatedassemblages of inclusions. The latter are randomlydistributed. Pseudosecondary inclusions as trail are observedalong sealed micro fractures (Fig. 11b).

Homogenization Temperature and Salinities

Fluid inclusions in the poly-metalic veins wereinvestigated at Tehran Tarbiat Moallem University (Iran).Reproducibility was within ±0.3 and ±1ºC for Tmice and Thvalues, respectively. Homogenization and ice-meltingtemperatures were obtained for 80 fluid inclusions in tensamples, and are summarized in Table 4. No clathrate

formation was observed in any of the fluid inclusions duringfreezing. Homogenization temperature (Th) of primaryinclusions ranges from 140-280ºC, with peaks at about180ºC and 250ºC (Fig. 12a). The salinity was calculatedfrom the Tmice values according to Bodnar (1993) equation.The salinity of the fluid inclusion range is from 4.7 to18 wt.% NaCl equivalent (Fig. 12b). Eutectic temperaturesare between -18.8° and -21.6º C for most samples, indicatingan H2O-NaCl composition. A diagram of the Th versussalinity of all the fluid inclusions (Fig.13) reveals theexistence of two fluids; (1) moderate-salinity fluidinclusions, of 4.7 to 8 wt.% NaCl equivalent and (2) fluidinclusions with salinities higher than 10 and up to 18 wt.%NaCl equivalent., that are postulated to represent differentmineralizing fluids, possibly dominated by meteoric andmagmatic fluids, respectively. Th versus Tmice diagramshows a large variation indicating linear dilution trend.Limited homogenization data were also obtained forsecondary calcite (data not presented) (barren stage), in rangeof 100° to 190 ºC (mean, 160 ºC, N=25). Determinations

Fig.11. Photomicrographs showing the distribution pattern of fluid inclusions in quartz from Cheshmeh Hafez deposit (a) primary fluidinclusion (L+V) in quartz (Qz); (b) trailed of fluid inclusions along sealed microfractures (pseudosecondary fluid inclusions;(c and d) shape of observed fluid inclusion.



made on secondary inclusions in quartz show that thehomogenization temperatures are very close to those ofcalcite.

DISCUSSION

Characteristics of Hydrothermal Fluids and Depths ofFormation

Homogenization temperatures versus salinity data forprimary fluid inclusions in quartz are plotted in Fig. 14. Inorder to understand the characteristics of hydrothermal fluidsat Cheshmeh Hafez, the results have been compared withother hydrothermal deposits containing lead, zinc, copperand some precious metal (Roedder, 1977; Olad and Morton,1985; Sawkins, 1990). The high-salinity and high-temperature values of the inclusions from the porphyrycopper deposits suggest that a fluid of probable magmaticorigin circulated in the porphyry systems, or magmatic andmeteoric fluids were mixed (Arribas et al. 1995). It is clearthat the salinity values could have been associated with amagma source, but they could also have been generated byheated basinal brines. The Cheshmeh Hafez quartz samplespartly yield microthermometry data similar to those of

hydrothermal Pb-Zn-Cu-Bi deposit at Bulancak (Sawkins,1990), and the Pb-Zn-Cu-Au-Ag deposit at Mayflower(Olade and Morton, 1985).

Some authors (Roedder, 1984; Bodnar, 1985; Muchez,2002) distinguish different types of epithermal ore deposits,a gold-rich type (1-8 wt.% NaCl equivalent), and a silver,base metal-rich type with higher salinity. For example, atFresnillo (Simmons, 1988) and other Mexican deposits(Albinson, 2001), salinity ranges are from ~ 5 to 20 wt.%NaCl equivalent, or even higher. Salinity determinationsindicate that quartz-hosted fluid inclusions at CheshmehHafez veins vary from 4.5 to 18 wt.% NaCl equivalent. TheCheshmeh Hafez samples (Table, 1) have average Ag/Auratios of ~28 and Pb+Zn contents with average of 6.8 wt%(Fig. 15), consistent with the maximum salinity at CheshmehHafez (18 wt. % NaCl equivalent). Such a relationshipbetween silver and base metal ores with relatively highersalinities and gold-silver ores with lower salinities has beenpreviously noted by Henley (1985) and later confirmed bySimmons (1988, 1991) and Albinson (2001) for Mexicanepithermal deposits.

The depth of formation below the paleowater table canbe estimated from hydrostatic boiling point curves (Hass,

Table 4. Microthermometric data of fluid inclusion from poly-metallic veins. Homogenization temperature Th; Eutectictemperature Te; Final ice melting temperature Tm

ice; Number of analyses n; not- measurable n.m.

Sample Mineral Inclusion type Th range Te Tmice Salinity(°C) °(c) range (wt%)

NaCl equiv

87-Ch-68 Quartz Primary 140-235 -19.6 to -20.5 -5 to -13.2 7.8 to 17.5(Three samples) (n=23) (n=19)

87-Ch- Tu Quartz Primary 160-260 -19.8 to -21.6 -2.9 to -8.2 4.7 to 12(Three samples) (n=22) (n=18)

87-Ch-23 Quartz Primary 157-255 -18.8 to -21.1 -4 to -14.3 6.2 to 18.0(Three samples) (n=26) (n=20)

87-Ch-33S Quartz Secondary 140-190 n.m n.m n.m(One sample) (n=10)

Fig.12. (a) Histograme of homogenization temperatures and (b) salinity of fluid inclusions in the Cheshmeh Hafez deposit.



1971), assuming hydrostatic pressure. However, because ofthe lack of evidence for boiling, such an estimate will providea minimum value. The average temperature of the secondgroup in the histogram, which represents an intermediate250°C, ~15 wt. % salinity fluid (Fig. 12), was fitted to the15 wt.% calculated boiling curve. The 25 wt.% boiling curveis also shown for reference. Based on the fluid compositions

it is suggested that the mineralization occurred at moderateepithermal depths in this district, with the present surfacebeing at a minimum of 380 m below the paleowater(Fig. 16).

Ore Deposit Model

Important features of the Cheshmeh Hafez mineralsystem include a Pb-Zn-Cu (Ag-Au-Bi-Sb-Mo)mineralization, open space filling and replacement texturesincluding crustiform banding, vugs with comb quartz, anore assemblage of pyrite, galena, sphalerite, chalcopyrite,tetrahedrite, bornite and digenite and alteration assemblages,typical of epithermal systems with average Ag/Au ratios of~ 28 and Pb+Zn contents with average of 6.8 wt.%. Gemmell(2004) compared the key features of intermediate-sulfidationand low-sulfidation epithermal systems. Important featuresof intermediate-sulfidation epithermal system include;(1) a pyrite, sphalerite, galena, tetrahedrite, chalcopyrite oreassemblages; (2) silver and base metal rich with high silverto gold ratios (10-1500); (3) the economic mineralizationoccurs over a wide vertical range of 300-800 m; (4) a greaterabundance of sulfide minerals (5-20 vol.%) compared tolow-sulfidation systems; (5) the presence of crustiformbanding and comb quartz; (6) Zn-Pb-Cu-Ag-Au with minorMo, As, and Sb metal signature; and (7) a proximal alterationassemblage that includes sericite but adularia is generallyuncommon (Sillitoe and Hedenquist, 2003; Gemmel, 2004;Dowens, 2006). Many of these features are present withinthe Cheshmeh Hafez epithermal system i.e., (1) a pyrite,sphalerite, galena, tetrahedrite, chalcopyrite, bornite anddigenite ore assemblages; (2) base metal rich with Ag/Au~28;

Fig.13. Homogenization temperature (Th) vs. salinity for fluidinclusions in quartz of the Cheshmeh Hafez poly-metalicdeposit, showing intermittent injection of mineralizing

brine that was subsequently diluted.

Fig.14. Homogenization temperatures (Th) versus salinity forprimary fluid inclusions. Data from porphyry copperdeposits, Providencia, Mississippi valley type, Mayflowerand Bulancak are from (Sawkins, 1990; Olade and Morton,1985; Akande et al, 1988). Diagonal grid lines show fluiddensities in gm/cm3 from the system NaCl-H

2O (Hass,

1970). Inclusions in Cheshmeh Hafez quartz occupy arange of 140-280 °C and 4.7-18 (wt% NaCl equivalent)which is shared by data from the Mayflower, Bulancakand Providencia deposits containing lead-zinc and copper.

Fig.15. Ternary diagram showing relative precious and base metalcontents of the Cheshmeh Hafez deposit (averages of veinsfrom Table 3). Ranges for Mexican epithermal deposits

are shown for comparison after Albinson, (2001).



(3) moderate depth of formation i.e. 380 m below thepaleowater table; (4) alteration assemblage; (5) Pb-Zn-Cu(Ag-Au-Bi-Sb-Mo) elements. Based on the aforementionedfeatures, the Cheshmeh Hafez mineral system is classifiedas an intermediate-sulfidation deposit (Hedenquist et al.2000; Einaudi et al. 2003; and Sillitoe and Hedenquist,2003). Intermediate-sulfidation epithermal system sharesmany of the sulfide assemblage’s characteristic of high-sulfidation systems, with the exception of enargite-bearingassemblages and the high Ag/Au ratio (Einaudi, 2003).Enargite has not been observed at Cheshmeh Hafez.Furthermore, alteration assemblages characteristic of high-sulfidation epithermal deposits, such as quartz-alunite,quartz-pyrophyllite and; or quartz-dickite Sillitoe and(Hedenquist, 2003), are not present at Cheshmeh Hafezdistrict. Low-sulfidation epithermal system tends to haveadularia, smectite and illite-bearing alteration assemblages.Presence of sericite (fine-grained muscovite) in CheshmehHafez district rather than adularia or quartz-alunite, quartz-pyrophyllite is characteristic of intermediate-sulfidationepithermal systems. Arsenopyrite is rare in intermediate-sulfidation epithermal deposits and is more characteristicsof low-sulfidation epithermal deposits. Arsenopyrite is notpresent in Cheshmeh Hafez district.

The host units and veins at Cheshmeh Hafez erodedafter the deposition, and resulted in the development ofextensive supergene mineralization. In the Cheshmeh

Hafez, geochemical data (Table 2) presents someinformation about the source of the metals. At CheshmehHafez, the base metal content of the host rock namelyandesitic, trachy-andesite, andesitic basalt and basalt ishigh. These geochemical results suggest that the hostrocks could have been an important source of metal for thesulfide veins, although the veins could also have beenderived from a magmatic fluid enriched in Pb-Zn and Cu.Silver and base metal transport in the epithermalenvironment is dominated by chloride complexes (Sewardand Barnes, 1997; Palyanova, 2008). These complexes aremore important for silver and base metal transport ratherthan for gold, under the relatively reduced, neutral pHconditions (Seward and Barnes, 1997) that characterizedthe epithermal systems of Cheshmeh Hafez. In contrast, theAu (HS) 2- bisulfide complex is most important species forgold transportation in the epithermal environment (Benningand Seward, 1996; Seward and Barnes, 1997), and thus goldtransport is not affected by salinity in the same way as silverand base metals. Boiling and mixing are the two principalphysical processes affecting mineral deposition inhydrothermal systems (Giggenbach and Stewart, 1982).Boiling occurs in the up flow of most high permeabilitysystems, whereas linear thermal profiles are common on themargins (due to mixing or low permeability; Hedenquist etal.1992). The relationship between fluid inclusion Th andTmice data from the Cheshmeh Hafez district clearly showsa trend of strong dilution due to the mixing of hot salinefluid with a cooler less saline fluid. Considering theparagenetic sequence of mineralization, and the systematicvariation of Th and Tmice between fluid inclusionassemblages in individual crystals of quartz from theCheshmeh Hafez district, it appears that the high-salinityfluid was periodically injected and mixed with lower salinityfluid over short periods of time. The main mechanism ofbase metal mineralization at Cheshmeh Hafez may have beendilution and cooling caused by the mixing of brines withthe more dilute solutions. The lack of fluid inclusionevidence for boiling does not preclude this mechanism.Indeed, abundant occurrence of muscovite and illiteassemblage within the proximal alteration zone suggest thatboiling conditions may have existed at the Cheshmeh Hafezepithermal system. Presence of lower and higher salinityfluids in the same deposit has also been noted in the silverand base metal deposits of Fresnillo district (Simmons, 1991)and in other intermediate-sulfidation epithermal deposits ofMexico (Albinson, 2001). High-salinity brines may evolvein a magmatic environment (Simmons, 1991; Albinson,2001).

The presence of illite, muscovite as alteration minerals

Fig.16. Fluid inclusion data from Cheshmeh Hafez (all samples)plotted on boiling point for depth curves of H

2O–NaCl (15

wt % NaCl equiv). The curves of pure H2O and 25 wt

percent NaCl are shown for reference from Haas, (1971).Cheshmeh Hafez data is fitted at 250 ºC Th values of the15 wt percent NaCl curve.



adjacent to mineralized veins suggests that the mineralizingfluid were weakly acidic to near neutral. In summary, basemetal mineralization of the Cheshmeh Hafez deposit appearsto have been caused by periodic introduction of a high-salinity fluid, with clear evidence of mixing between thisfluid with fluid of moderate salinity.

CONCLUSIONS

At Cheshmeh Hafez, Pb-Zn-Cu-Ag-Au veins occurredalong the major faults, and the general morphology,paragensis and the location of the mineralization arestructurally controlled. The Cheshmeh Hafez poly-metalsystem is related to calc-alkaline magmatism of the Tertiaryage. Host rocks are mainly Tertiary andesitic, trachy-andesite, rhyo-dacitic and dacitic.

The mineral paragenesis of the vein mineralization canbe subdivided into stage 1, main sulfide stage 2, and stage 3supergene stage. The stage 1 alteration is represented byepidote, chlorite (clinochlore), calcite and quartz with pyriteI and chalcopyrite. Main sulfide stage is characterized bydeposition of medium and coarse-grained quartz, initiallyeuhedral galena I, followed by galena II and sphalerite,followed finally by the deposition of galena III, pyrite II,chalcopyrite, tetrahedrite, bornite and digenite. Stage 3involves the deposition of quartz and calcite barren veinswith minor pyrite. The supergene mineral assemblageconsists of chalcocite, covellite, cerussite, malachite and Fe-oxy-hydroxides.

The district is dominated by base metal mineralizationand gold is relatively low in the veins. Base metal sulfides

within the Cheshmeh Hafez veins were deposited duringperiodic injection of high- temperature metalliferous brines.Dilution and cooling were the main precipitation mechanismat Cheshmeh Hafez, caused by the mixing of brines withthe more dilute fluids. The mineralogy of ore, gangue, andalteration products combined with fluid inclusion data fromCheshmeh Hafez indicates an intermediate-sulfidationepithermal mineralization and share characteristics withthose of major districts in Mexico, western United States,and Peru. The presence of geochemical anomalies andoccurrence of ores in the abandoned mines (Fig. 1b) withsimilar epithermal characteristics suggests that the Troud-Chah Shirin mountain range is prospective for precious andbase metal epithermal deposits. The recognition of alterationand sulfide mineralogy at a deposit-scale may provideinitiatives for exploring intermediate-sulfidation epithermaldeposits. The Troud-Chah Shirin mountain range is animportant exploration target, as the area may have thepotential at depth for high-grade veins, particularly wherethere is evidence for the presence of relatively low salinityhydrothermal systems. In addition, the presence of othertypes of deposits indicates that this region has potential forvariety of volcanic-hosted mineralization. Much of theepithermal mineral potential of this area, and the adjacentregions remain unexplored.

Acknowledgement: This study was financially supportedby Iranian mineral research and application (IMRA) Co.,for their assistance in the analytical aspects; we would liketo thank, Mr. Hedayati and Mr Eghbali.

References

AGHANABATI, A. (2003) Geology of Iran. Geol. Surv. Iran, pp.123-147.

AKANDE, S.O., HORN, E.E. and REUTEL, C. (1988) Mineralogy, fluidinclusion and genesis of the Arufu and Akwana Pb-Zn-Fmineralization, middle Benue Trough, Nigeria. Jour. AfricanEarth Sci., v.7, pp.167-180.

ALAVI, M. (1991) Tectonic Map of Middle East. Geol. Surv. Iran.ALBINSON, T., NORMAN, D.I. COLE, D. and CHOMIAK, B. (2001)

Controls on formation of low-sulfidation epithermal depositsin Mexico: Constrains from fluid inclusion and stable isotopedata. Soc. Econ. Geol., Spec. Publ. no.8, pp.1-32.

ARRIBAS, A., CUNNINGHAM, C.G., RYTUBA, J.J., RYE, R.O., KELLY,W.C., PODWYSOCKI, M.H., MCKEE, E.H. and TOSDAL, R.M.,(1995) Geology, geochronology, fluid inclusion and isotopegeochemistry of the Rodalquilar Au alunite deposits, Spain.Econ. Geol., v.90, pp.795-822.

AZIZI, H. and JAHANGIRI, A. (2008) Cretaceous subduction-relatedvolcanism in the Northern Sanandaj Sirjan zone, Iran. Jour.Geodyn, v.45, pp.178-190.

BARNES, H.L. (Ed.), (1979) Solubility’s of ore minerals. Geochem-istry of hydrothermal ore deposits. Wiley, NY, pp.404-460.

BENNING, L.G. and SEWARD, T.M. (1996) Hydrosulfide complexingof Au in hydrothermal solutions from 150 to 400 ºC and 500 to1500 bars, Geochim. Cosmochim. Acta, v.60, pp.1849–1871.

BODNAR, R.J. (1993) Revised equation and table for determiningthe freezing point depression of H2O-NaCl solutions, Geochim.Cosmochim. Acta, v.57, pp.683-684.

COLLINS, P.L.F. (1979) Gas hydrate in CO2-bearing fluid inclusionsand the use of freezing data for estimation of salinity. Econ.Geol., v.74, pp.1435-1444.

COOKE, D.R. and SIMMONS, S.F. (2000) Characteristics and genesis ofepithermal gold deposits. Rev. Econ. Geol., v.13, pp.221-244.

DOWNES, P.M. (2006) Yerranderie a Late Devonian Silver–Gold–Lead intermediate sulfidation epithermal district, EasternLachlan Orogen, New South Wales, Australia: ResourceGeology, v.57, pp.1-23.

EINAUDI, M.T., HEDENQUIST, J.W. and INAN, E.E., (2003) Sulfidationstate of fluids in active and extinct hydrothermal systems:



Transitions from porphyry to epithermal environments. Soc.Econ. Geol. Spec. Publ., no.10, pp.285-313.

GEMMELL, J.B. (2004) Low and intermediate-sulfidation epithermaldeposits, ARC- AMIRAP, Australia, pp.57-63.

GEMMEL, B. (2006) Exploration implication of hydrothermalalteration associated with epithermal Au-Ag deposits, ARC-AMIRAP 588, pp.1-5.

GEOLOGICAL SURVEY OF IRAN (1995) Explanatory text of geochemicalmap of Moaleman (6960), Report No. 9, v.1, 33 p.

GIGGENBACH, W.F. and STEWART, M.K. (1982) Processes controllingthe isotopic composition of steam and water discharges fromsteam vents and steam-heated pools in geothermal areas:Geothermics, v.11, pp.71-80.

GRANCEA, L. and BAILLY, L. (2002) Fluid evolution in the BaiaMare epithermal gold- poly-metalic district. Carpathians,Romania, Mineralium Deposita, pp.630-647.

HAAS, J.L. (1971) The effect of salinity on the maximum thermalgradient of a hydrothermal system at hydrostatic pressure:Econ. Geol., v.66, pp.940-946.

HASSANZADEH, J., GHAZI, A.V. AXEN, G. and GUEST, B. (2002)Oligomiocene mafic-alkaline magmatism in north andnorthwest of Iran: Evidence for the separation of the Alborzfrom the Urumieh-Dokhtar magmatic arc. Geol. Soc. Amer.Abs. with Program, v.34, no.6, p.331.

HEDENQUIST, J.W., ARRIBAS R., A. and GONZALEZ-URIEN, E. (2000)Exploration for epithermal gold deposits: Reviews in Econ.Geol., v.13, pp.245-277.

HUSHMANDZADEH, A.R., ALAVI NAINI, M. and HAGHIPOUR, A.A.(1978) Evolution of geological phenomenon in Troud area:Geol. Surv. Iran, Report No.H5, 136 p (in Persian).

JIMENEZ, F.A., YUMEL, G.P. and MAGLAMBAYAN, V.B. (2002) Shallowto near- surface, vein type epithermal gold mineralization at Lalabin the Sibutad gold deposit, Zambanaga Del North, Mindanao,Philippines. Jour. Asian Earth Sci., v.21, pp.119-133.

KENNEDY, A.K., GROVE, T.L. and JOHNSON, R.W. (1990)Experimental and major element constraints on the evolutionof lavas from Lihir Island, Papua New Guinea. Contrib.Mineral. Petrol., v.104, pp.722-734.

KOUZMANOV, K., MORITZ, R., VON QUADT, A.V., CHIARADIA, M.,PEYTCHEVA, I., FONTIGNIE, D., RAMBOZ, C. and BOGDANOV, K.(2009) Late Cretaceous porphyry Cu and epithermal Cu– Auassociation in the Southern Panagyurishte District, Bulgaria:the paired Vlaykov Vruh and Elshitsa deposits. MineraliumDeposita, v.44, pp.611-646.

MOAYYED, M. (2001) Geochemistry and petrology of volcano-plutonic bodies in Tarum area, PhD thesis (in Persian), p.256.

MULLER, D., ROCK, N.M.S. and GROVES, D.I. (1992) Geochemicaldiscrimination between shoshonitic and potassic volcanic rocksin different tectonic settings, a pilot study. Mineral. Petrol.,v.46, pp.259-289.

OLADE, M.A. and MORTON, R.D. (1985) Origin of lead-zincmineralization in the Southern Benue Trough, Nigeria-fluidinclusion and trace element studies. Mineralium Deposita, v.20,pp.76-80.

ORGAN, Y. and GULTEKIN, A. (2004) Geology, mineralogy and fluidinclusions data from the Arapucan Pb-Zn-Cu-Ag deposit,

Canakle, Turkey. Jour. Asian Earth Sci., v.25, pp.629-642.PALYANAOVA, G. (2008) Physicochemistry modeling of the coupled

behavior of gold and silver in hydrothermal processes, goldfineness, Au/Ag ratios and their possible implications. Chem.Geol., v.255, pp.399-413.

PEARCE, J.A. (1982) Trace element characteristics of lavas fromdestructive plate boundaries. In: R.S. Thorpe (Ed.), Wiley,New York, pp.525-548.

PEARSE, J.A. and PEATE, D.W. (1995) Tectonic implications of thecomposition of the volcanic arc magmas. Annual Revi. EarthPlanet. Sci., v.23, pp.251-285.

ROEDDER, E. (1972) Composition of fluid inclusions. USGS Prof.Paper Jj-440, p.164.

ROEDDER, E. (1984) Fluid inclusions: Reviews in Mineralogy,v.12, 644p.

SAWKINS, F.J. (1990) Metal deposits in relation to plate tectonics.Springer, New York, 461p.

SEWARD, T.M. and BARNES, H.L. (1997) Metal transport byhydrothermal ore fluids. In: H.L. Barnes (Ed.) Geochemistryof hydrothermal ore deposits. New York, John Wiley and Sons,pp.435-486.

SCHMIDT, G., PALME, H. KRATZ, K.L. and KURAT, G. (2000). Arehighly siderophile elements ZPGE, Re and Au, fractionatedin the upper mantle of the earth, new results on peridotitesfrom Zabargad, Chem. Geol., v.163, pp.167-188.

SHAMANIAN, H., GEFFREY, W., HEDENQUIST, J., HATORI, K. andGHADERI, M. (2003) The Gandy and Abolhassani epithermalprospects in the Alborz magmatic arc, Semnan province,Northern Iran. Econ. Geol., v.99, pp.691-712.

SHEPHERD, T.J., RANKIN, A.H. and Alderton, D.H.M. (1985)A practical guides to fluid inclusion studies. Blackie Press,239p.

SILLITOE, R.H. and HEDENQUIST, J.W. (2003) Linkages betweenvolcano-tectonic settings, Ore-fluid compositions andepithermal precious metal deposits. Soc. Econ. Geol., Spec.Publ., No.10, pp.315-343.

SIMMONS, S.F., GEMMELL, B. and SAWKINS, F.J. (1988) The SantoNino silver-lead-zinc vein, Fresnillo district, Zacatecas,Mexico: Part II. Physical and chemical nature of ore-formingsolutions: Econ. Geol., v.83, pp.1619-1641.

SIMMONS, S.F. (1991) Hydrothermal implications of alteration andfluid inclusion studies in the Fresnillo district, Mexico:Evidence for a brine reservoir and a descending water tableduring the formation of hydrothermal Ag-Pb-Zn ore bodies.Econ. Geol., v.86, pp.1579-1601.

SIMMONS, S.F., WHITE, N.C. and JOHN, D.A. (2005) Geologicalcharacteristics of epithermal precious and base metal deposits,Econ. Geol. 100th Anniversary Volume, Soc. Econ. Geologists,Littleton, CO, pp.485-522.

STOCKLIN, J. and NABAVI, M.H. (1973) 1/250000 Sheet Tectonicmap of Iran, Geological Survey of Iran.

STOCKLIN, J. (1968) Structural history and Tectonic of Iran, a review,Amer. Assoc. Petrol Geol. Bull., v.52, pp.1229-1258.

WILKINSON, J.J. (2001) Fluid Inclusion in hydrothermal ore deposit,Lithos 55, 229-272.

WILSON, M. (1989) Igneous petrogenesis, Unwin Hyman, 466p.

(Received: 19 May 2010; Revised form accepted: 7 June 2011)

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