Journal of Economic Geology

179-202

Authors: Mohammad Ali Jazi, Mohammad Hassan Karimpour and Azadeh Malekzadeh Shafaroudi

Introduction
The Baqoroq Cu-Zn-As deposit is located northeast of the town ofAnarak in Isfahan province, in theeast central areaof Iran. Copper mineralization occursin upper cretaceous carbonate rocks.Studyof thegeologyof the Nakhlak area, the location ofa carbonate-hosted base metaldeposit, indicatesthe importance of stratigraphic, lithological and structural controls in the placement of this ore deposit. (Jazi et al., 2015).Some of the most world’s most important epigenetic, stratabound and discordant copperdeposits are the carbonate hosted Tsumeb and Kipushi type deposits,located in Africa. The Baqoroq deposit is believed to be of this type.

Materials and methods
In the current study, fifty rock samples were collected from old tunnels and surface mineralization. Twenty-two thin sections, ten polished sections and four thin-polished sections were prepared for microscopic study. Ten samples were selected for elemental analysis by ICP-OES (Inductively coupled plasma optical emission spectrometry) by the Zar Azma Company (Tehran) and AAS (Atomic absorption spectrometry) at the Ferdowsi University of Mashhad. Seven doubly polished sections of barite mineralization were prepared for microthermometric analysis. Homogenization and last ice-melting temperatures were measured using a Linkam THMSG 600 combined heating and freezing stage at Ferdowsi University of Mashhad. Sulfur isotopes of five barite samples were determined by the Iso-Analytical Ltd. Company of the UK. The isotopic ratios are presented in per mil (‰)notation relative to the Canyon Diablo Troilite.

Results
The upper Cretaceoushost rocks of the Baqoroq deposit include limestone, sandstone, and conglomerate units. Mineralization is controlled by two main factors: lithostratigraphy and structure. Epigenetic Cu-Zn mineralizationoccurs in ore zones as stratabound barite and barite-calcite veins and minor disseminated mineralization. Open space filling occurred as breccia matrix, crustification banding,andbotryoidaltexture. The host rock has undergone dolomitization alteration Hypogene minerals include chalcopyrite, pyrite, sphalerite, galena, enargite, barite, and calcite. Supergene minerals include malachite, azurite, covellite, chrysocolla, chalcocite, cerussite, smithsonite, native copper and iron oxide minerals. Sulfantimonides and sulfardenides are abundant in low- and moderate temperature stages of the deposit, while bismuth sulfides generally occur in higher temperature ores, according to Malakhov, 1968.
Analysis of rich ore samples indicates copper is the most abundant heavy metal in the ore (average 20.28 wt%), followed by zinc (average ~ 1 wt%) and arsenic (average ~ 1 wt%), respectively. Thepresence of many trace elements in the ore, such as Sb, Pb, Ag and V, are very important. Element pairs such as Ag-Cu, Zn-Cd, Zn-Sb, Fe-V and Pb-Mo are correlated with each other. The Baqoroq ore minerals are rich in As, Sb and poor in Bi. Highamountsof antimony usually occur in a low temperature stage (Marshall and Joensuu, 1961). Malakhov (1968) suggested thata high Sb/Biratio in the ore indicates a low temperature of formation for the Baqoroq deposit. Sulfide mineralization fluids were found to have homogenization temperatures between 259 and 354°C and salinities between 8.37 and 13.18 wt% NaCl eq. Surface water apparently diluted theore-bearing fluids in the final stages and deposited sulfide-freecalcite veins at relatively low temperatures (78 to 112 °C) and low salinities (3.59 to 6.07 wt% NaCl eq.).
The δ34S values of barite of the Baqoroq deposit range from +13.1 to +14.37‰from whichδ34S values of ore fluids were calculated to vary between -8.57‰ and -7.23‰. Sulfur within natural environments is derived ultimately from either igneous or seawater sources (Ohmoto and Rye, 1979). Barite δ34S values of Baqoroq deposit lie within the range of Cretaceous-age oceanic sulfate values. The reduction of sulfate to sulfide couldhave been caused either by bacterial sulfate reduction or by nonbacterial sulfate reduction through a reaction with organic materialin the sedimentary rocks (thermochemical sulfate reduction). However, the narrow range of δ34S and positive values indicates that they were not produced by bacterial sulfate reduction.Partial thermochemical reduction of sulfates has apparently produced light sulfurvalues (~ 21‰ lighter) and it has been effective inthe deposition of ore minerals. Organic matter occurs as graphite in the Baqoroq formation in proximity of Baqoroq deposit (Cherepovsky et al., 1982).

Discussion
Epigenetic, stratabound and discordant Cu-Zn-As mineralization in the Baqoroq deposit occurs as open space filling of upper Cretaceous rocks. Host rock is partially dolomitized by ascending warm, saline fluids. Seawater sulfates were the source of the sulfidesulfur and the sulfate in the barite. The reduced sulfur was generated by partial thermochemical reduction and it was effective inthe deposition ofthe ore minerals. Based onthe evidence of carbonate host rocks, the absence of igneous activity, the open space filling texture, mineralogy, dolomite alteration, ore geochemistry (As and Sb high content and absence of Bi), microthermometric data of ore bearing fluid and sulfur isotope values, the Baqoroq deposit is very similar to the carbonate hosted copper deposits in Africa and in particular the Tsumeb deposit in Namibia. The Baqoroqdepositmay have been produced bymetamorphicfluids during orogenyrelated to theclosureof the Neo-Tethys ocean.

References
Cherepovsky, N., Plyaskin, V., Zhitinev, N., Kokorin, Y., Susov, M., Melnikov, B. and Aistov, L., 1982. Report on detailed geological prospecting in Anarak area (Central Iran) Nakhlak locality. Geological Survey of Iran and Technoexport Company, Tehran. Report 14, 196 pp.
Jazi, M.A., Karimpour, M.H., Malekzadeh, A. and Rahimi, B., 2015. Stratigraphic, lithological and structural controls in placement of Nakhlak deposit (northeast of Esfahan). Advanced Applied Geology, 15(1): 59-75. (in Persian with English abstract)
Malakhov, A.A., 1968. Bismuth and antimony in galena as indicators of some conditions of ore formation. Geochemistry International, 7(11): 1055-1068.
Marshall, R.R. and Joensuu, O., 1961. Crystal habit and trace element content of some galena. Economic Geology, 56(4): 758-771. Ohmoto, H. and Rye, R.O., 1979. Isotopes of sulphur and carbon. In: H.L. Barnes (Editor), Geochemistry of Hydrothermal Ore Deposits. Wiley-Interscience, New York, pp. 509-567.

225-241

Authors: Fereshteh Bayat and Ghodrat Torabi

Introduction
The occurrence of blueschist metamorphic facies is believed to mark the existence of former subduction zones. This facies is represented in the main constituents of subduction-accretion complexes, where it occurs in separate tectonic sheets, imbricated slices, lenses, or exotic blocks within a serpentinite mélange (Volkova et al., 2011). The evidence of the presence and maturity of Paleo- Tethys oceanic crust in the CEIM (define this) in Paleo-Tethys branches, subduction and collision has been studied by various authors (Bagheri, 2007; Zanchi et al., 2009; Bayat and Torabi, 2011; Torabi 2011). Late Paleozoic blueschists have recognized in the western part of the CEIM (e. g. Anarak, Chupanan and Turkmeni) in linear trends. Metamorphic rocks of the Turkmeni area (SE of Anarak) are composed of blueschist and meta-greywacke and are situated along the Turkmeni-Ordib fault associated with Paleozoic rock units and serpentinized peridotite bodies. Turkmeni blueschist and meta-greywackes have not been studied by previous workers.
The Turkmeni blueschists consist of albite, winchite, actinolite and epidote. Granoblastic, nematoblastic and lepidoblastic are main textures in these rocks. Winchite is found in the matrix and around epidote grains. This sodic-calcic amphibole serves as an index mineral in blueschist facies. Actinolite and epidote formed during retrograde metamorphism of blueschists in the greenschist facies. The mineral assemblage of albite, epidote, chlorite and phengite ± garnet is present in meta-greywackes in the Turkmeni blueschists. Veins of garnet, muscovite, quartz and opaque minerals are extensive in these rocks. Epidote and chlorite formed in meta-greywackes by retrograde metamorphism in the greenschist facies. The aim of the present study is to determine the petrological and geochemical characteristics, P-T condition of blueschists and meta-greywackes, as well as the geotectonic setting of primary basaltic rocks of the Turkmeni blueschists.

Material and methods
This study is based on field observations and petrographical and analytical studies. Satellite images and a geological map were prepared. About 20 thin sections were supplied for petrological studies. Mineral chemical analyses were carried out by a JEOL JXA-8800R electron probe micro-analyzer (EPMA) at the Cooperative Center of Kanazawa University, Japan. The analyses were performed under an accelerating voltage of 15 kV and a beam current of 15 nA with 3µm probe beam diameter. The Fe3+ contents of minerals were estimated by assuming ideal mineral stoichiometry. The representative mineral compositions are given in Tables 1-3. Major oxides, rare earth elements (REE) and trace elements of five blueschists samples were analyzed by the ICP-MS method (Kanpanzhouh Research Company, Tehran, Iran) of the SGS laboratory of Canada. Whole rock chemical data are presented in Table 4.

Results and discussion
Petrographical and geochemical characteristics of Turkmeni blueschists reveal that they were derived from a similar mantle source and underwent analogous melt extraction and post magmatism occurrences. According to the trace and rare earth elements contents, the protolith of blueschists should be formed by crystallization of tholeiitic basalt and have sub-alkali basalt nature. Blueschists have LREE values more than HREE. High amounts and evident variations of LIL elements are obvious. Negative anomalies of HFSE such as Nb, Hf, Zr and Ti are evident in Turkmeni blueschist. REE trends of these rocks resemble as the back arc basin basalts. Based on the Nb/La ratio and REE contents, the original magma has been generated by low to medium degree of partial melting of a lithospheric mantle spinel lherzolite. Geochemical characteristics and normalized diagrams reveal that primary magma of protolith has been nature near to IAB and E-MORB. The related processes to subduction of Paleo-Tethys oceanic crust led to mantle enrichment and carbonate metasomatism. The Paleo-Tethys Ocean spreading in CEIM commenced in Late Ordovician and terminated in the Late Paleozoic-Triassic. Association of meta-greywackes with blueschist and LILE/HFSE contents shows that Paleo-Tethys oceanic crust subduction zone at Turkmeni region was been immature. Mineral chemistry and assemblages of the blueschists and meta-greywackes units reveal that they suffered different metamorphic evolution: (M1) greenschist metamorphism by existence of actinolite and albite in basaltic rocks, and then they passed a prograde metamorphism in the blueschist facies by existence of winchites (M2) which is followed by a retrograde metamorphism P-T condition in the greenschist facies (M3). Variscan tectono-metamorphism occurrence has been main metamorphic phase in Anarak region and it has led to metamorphism in blueschist facies of Turkmeni rocks.

Acknowledgments
The authors wish to thank the University of Isfahan University for financial supports.

Reference
Bagheri, S., 2007.The exotic Paleo-tethys terrane in Central Iran: new geological data from Anarak, Jandaq and Posht-e-Badam areas. Ph.D. thesis, Faculty of Geosciences and Environment. University of Lausanne, Switzerland, 208 pp.
Bayat, F. and Torabi, G., 2011. Alkaline lamprophyric province of Central Iran, Island Arc, 20(3): 386-400.
Torabi, G., 2011. Late Permian blueschist from Anarak ophiolite (Central Iran, Isfahan province), a mark of multi-suture closure of the Paleo-Tethys ocean. Revista Mexicana de Ciencias Geológicas, 28(3): 544-554.
Volkova, N.I., Travin, A.V. and Yudin, D.S., 2011. Ordovician blueschist metamorphism as a reflection of accretion-collision events in the Central Asian orogenic belt. Russian Geology and Geophysics, 52(1): 72-84.
Zanchi, A., Zanchetta, S., Garzanti, E., Balini, M., Berra, F., Mattei, M. and Muttoni, G., 2009. The Cimmerian evolution of the Nakhlak – Anarak area, Central Iran, and its bearing for the reconstruction of the history of the Eurasian margin. Geological Society, London, Special Publications, 312: 261-286.

259-276

Authors: Mohammad Ali Rajabzadeh and Fatemeh Al Sadi

Introduction
Worldwide, Ni-Cu and PGE magmatic sulfide deposits are confined to the lower parts of stratiform mafic and ultramafic complexes. However, ophiolite mafic and ultramafic complexes have been rarely explored for sulfide deposits despite the fact that they have been extensively explored and exploited for chromite. Sulfide saturation during magmatic evolution is necessary for sulfide mineralization, in which sulfide melts scavenge chalcophile metals from the parent magma and concentrate them in specific lithological zones. The lack of exploration for sulfides in this environment suggests that sulfide saturation is rarely attained in ophiolite-related magmas. Some ophiolites, however, contain sulfide deposits, such as at Acoje in Philippines, and Cliffs in Shetland, U.K. (Evans, 2000; Naldrett, 2004). The Faryab ophiolite complex in southern Kerman Province, the most important mining area for chromite deposits in Iran, is located in the southwest part of the Makran Zone. Evidence of sulfide mineralization has been reported there by some authors (e.g. Rajabzadeh and Moosavinasab, 2013). This paper discusses the genesis of sulfides in the Faryab ophiolite using mineral chemistry of the major mineral phases in different rocks of the ophiolite column in order to determine the possible lithological location of sulfide deposits.

Materials and methods
Seventy three rock samples from cumulate units were collected from surficial occurrences and drill core. The samples were studied using conventional microscopic methods and the mineralogy confirmed by x-ray diffraction. Electron microprobe analysis was carried out on different mineral phases in order to determine the chemistry of the minerals used in the interpretation of magma evolution in the Faryab ophiolite.
Lithologically, the Faryab ophiolite complex is divided into two major parts: the northern part includes magmatic rocks and the southern part is comprised of rocks residual after partial melting of the upper mantle. Sulfide mineralization in the complex is confined to cumulate rocks in northern part of ophiolite column. The mineralization is olivine-rich clinopyroxene and wehrlite. Petrographic investigation of sulfides in host ultramafics indicated two sulfide generations. In the first generation, primary magmatic sulfides occurred as interstitial disseminations, generally as anhedral grains. In the second generation, sulfides formed as veinlets along host rock fractures. The primary sulfides include pyrrhotite, pentlandite, and secondary digenite and pyrite. The primary sulfide content increases with increasing size and amount of clinopyroxene in host rocks. Associated chromian spinels in host ultramafics display disseminated and massive textures.

Discussion
Generally, mineralization in ophiolites is controlled by two major steps: a) partial melting of upper mantle rocks and b) crystal fractionation in a magma chamber (Rajabzadeh and Moosavinasab, 2013). The chemical compositions of the analyzed minerals were then used in estimating the conditions in these two steps. The composition of chromian spinel corresponds to chromite of boninitic melts formed in supra-subduction zone environments. Boninitic melts are produced at high degrees of partial melting of mantle peridotites in the presence of water (Edwards et al., 2002). Silicates of the host rocks are mainly clinopyroxene (diopside and augite) of the composition Wo47.50 En45.48 Fs3.4, olivine Fo92 and orthopyroxene (enstatite - bronzite) of En85 to En88. The main host ultramafic rocks of sulfides are wehrlite and clinopyroxenite, indicating that the sulfide saturation occurred during magmatic evolution of these rocks. This suggests that sulfide mineralization will occur in the northern part the ophiolite. The sulfide grains are anhedral, amoeboidal in shape, and appeared as disseminated interstitial phases, indicating that they were trapped as liquid phases during increase in sulfur fugacity and decrease in FeO content and temperature of crystallization of clinopyroxene-rich rocks (Talkington et al., 1984; Von Gruenewaldt et al., 1990). Nickel-rich pentlandite is the main sulfide in the Faryab complex. The composition of this is mineral is consistent with the crystallization in an equilibrium condition (Song et al., 2008). The sulfide may have been introduced from external sources during upward movement and emplacement of parent magma.

Acknowledgments
The authors are grateful to the Research Council of Shiraz University for financially supporting this study.

References
Edwards, S.J., Pearce, J.A. and Freeman, J., 2002. New insights concerning the influence of water during the formation of podiform chromitite. Geological Society of America, Special Paper, 349 (3) 139-147.
Evans, A.M., 2000. Ore geology and industrial minerals. An Introduction. Black well Pub, Oxford, London, 389 pp.
Naldrett, A.J., 2004. Magmatic Sulfide Deposits: Geology, Geochemistry and Exploration. Springer, New York, 727 pp.
Rajabzadeh, M.A., Moosavinasab, Z., 2013. Mineralogy and distribution of Platinum-Group-Minerals (PGM) and other solid inclusions in the Faryab ophiolitic chromitites, Southern Iran. Mineralogy and Petrology, 107 (6): 943-962.
Song, X., Zhou M., Tao Y., and Xia, J., 2008. Controls on the metal compositions of magmatic sulfide deposits in the Emeishan large igneous province, SW China. Chemical Geology, 253 (1-2): 38-49.
Talkington, R.W., Watkinson, D.H, Whittaker P.J., Jones P.C., 1984. Platinum group minerals and other solide inclusions in chromite of ophiolitic complexes: occurrences and petrological significance. Tschermakes Mineralogische und Petrographische Mitteilungen, 32 (4): 285-301.
Von Gruenewaldt, G., Dicks, D., Wet J. and Horsch, H., 1990. PGE mineralization in the western sector of the Eastern Bushveld complex. Mineralogy and Petrology, 42 (1): 71-95.

307-325

Authors: Arash Gorabjeiri Puor and Mohsen Mobasheri

Introduction
The Mahour exploration area is a polymetallic system containing copper, zinc and silver. The mineralization can be seen in two forms of veins and disseminations. This area is structurally within the Lut block, west of Deh-salm Village. Recent exploration work and studies carried out by geologists on this volcanic-plutonic area of Lut demonstate its importance indicating new reserves of copper, gold, and lead and zinc.
Several articles have been published on the Mahour deposit in recent years, including work on fluid inclusions (Mirzaei et al., 2012a; Mirzaei et al., 2012b).
The present report aims at completion of previous studies on Mahour. During the course of this research, the IP/RS geophysical methods were used to locate the extent and depth of sulfide veins in order to locate drill sites. The IP/RS method has been used extensively worldwide in locating sulfide mineralization at deposits such as Olympic Dam in Australia (Esdale et al., 1987), Hishikari epithermal gold deposit in Kagoshima, Japan (Okada, 1995) and Cadia-Ridgeway copper and gold deposit in New South Wales, Australia (Rutley et al., 2001).

Materials and Methods
1. Determination of mineralogy of ore and alteration by examination of 70 thin sections and 45 polished sections.
2. Compilation of geological and mineralization maps of the studied area at a scale of 1:1000.
3. Geological, alteration, mineralization and trace element geochemical studies of 6 drill holes.
4. IP/RS measurements for 2585 points on a rectangular grid with profile intervals of 50 meters and electrode intervals of 20 meters.
5. Interpretation of IP/RS results.

Discussion
The Mahour area is covered by a volcanic sequence of basalt, andesite, dacite, rhyolite and pyro-clastics. During the Late Eocene through Early Oligocene this volcanic complex was intruded by several diorite and quartz-diorite bodies, which were responsible for mineralization of the area. Mineralized veins hosted by dacite show NNE trends with 85 t0 90° dips, and which are accompanied by argillic, silicic, quartz-sericite-pyrite and propylitic alteration zones. The primary minerals include pyrite, chalcopyrite, sphalerite, galena, tetrahedrite, and quartz along with supergene minerals such as malachite, atacamite, azurite and goethite. High anomalies of copper (up to 103062 ppm), zinc (up to 213520 ppm) and silver (up to 1988 ppm) are present in the studied area.
The IP/RS surveys were carried out on profiles perpendicular to the veins. The chargeability levels reached 40 msce, indicating the presence of sulfide minerals in the area. Two especially anomalous resistivity zones, high and low, were detected within the deposit. The high resistivity zone, up to 350 ohm.m, occurs along geophysical profiles in association with less-crushed zones, whereas the low anomaly zone is related to highly crushed zones.
The geophysical anomalies agree with drilling results indicating zones of highest mineralization.

Results
Generally, the chargeability surveys have clearly revealed two anomalous zones: one in the northeast and the other in the southwest of the studied area. Six holes have been drilled through these anomalous zones and geochemical samples taken at intervals of 1 meter in each hole. Most of the anomalies are associated with quartz-sericite-pyrite, silicification and chloritic alteration as well as the intense distribution of secondary iron oxides.
Geochemical results from the drill holes show the highest anomalies as follows:
GBH-1, 78-92 m, 246-281 m GBH-3 20-40 m and 133-152 m
GBH-7 20-32 m and 57-65m
PB-1 85-94 m. and 133-140 m
PD-1. 50-55 m, 298-301 m and 360-365 m
PA-1 48-57 m, 152-161 m and 212-218 m

References
Esdale, D.J., Pridmore, D.F., Coggen, J.H., Muir, P.M., Williams, P.K. and Fritz, F.P., 1987. Olympic Dam deposite- Geophysical case history. Journal of the Australian Society of Exploration Geophysics, 18(2): 47- 49. Mirzaei Rayni, R., Ahmadi, A. and Mirnejad, H., 2012a. The origin of ore-forming fluids in the Mahour polymetal ore deposit, using electron microprobe data and sulfur isotopes, East of Lut block, Central Iran. Journal of Petrology, 3(10): 1-12. (in Persian with English abstract)
Mirzaei Rayni, R., Ahmadi, A. and Mirnejad, H., 2012b. Study of mineralogy and fluid inclusions in the Mahour polymetal ore deposit, East of Lut block, Central Iran. Iranian Journal of Crystallography and Mineralogy, 20(2): 307-318.(in Persian)
Okada, K., 1995. Geophysical exploration for epithermal gold deposits: Case studies from the Hishikari gold mine, Kagoshima, Japan. Journal of the Australian Society of Exploration Geophysics, 26(3): 78- 83.
Rutley, A., Oldenburg, D.W. and Shekhtman, R., 2001. 2-D and 3-D IP/resistivity inversion for the interpretation of Isa-style targets. Journal of the Australian Society of Exploration Geophysics, 32(4): 156-159.

343-367

Authors: Mohammad Maanijou, Masoumeh Vafaei Zad and Farhad Aliani

Introduction
The Ahangaran Pb-Ag deposit is located in the Hamedan province, west Iran, 25 km southeast of the city of Malayer . . The deposit lies in the strongly folded Sanandaj-Sirjan tectonic zone, in which the ore bodies occur as thin lenses and layers. The host rocks of the deposit are Early Cretaceous carbonates and sandstones that are unconformably underlain by Jurassic rocks. Ore minerals include galena, pyrite, chalcopyrite, pyrrhotite and supergene iron oxide minerals. Gangue minerals consist of barite, dolomite, chlorite, calcite and quartz. The mineralization occurs as open-space fillings, veins, veinlets, disseminations, and massive replacements. Alteration consists of silicification, sericitization, and dolomitization. In this study, we carried out studies of mineralogy, microthermometry of fluid inclusions and sulfur isotopes to determine the source of sulfur and the physico-chemical conditions of formation.

Materials and methods
Seventy samples of different host rocks, alteration, and mineralization were collected from surface outcrops and different tunnels. Twenty of the samples were prepared for mineralogical studies at Tarbiat Modarres University in Tehran and 25 for petrological studies at the University of Bu-Ali Sina. Fluid-inclusion studies were done on 5 samples of quartz and calcite at Pouya Zamin Azin Company in Tehran using a Linkam THM 600 model heating-freezing stage (with a range of -196 to 480ºC). The accuracy and precision of the homogenization measurements are about ±1°C. Salinity estimates were determined from the last melting temperatures of ice, utilizing the equations by Bodnar and Vityk (1994) and for CO2 fluids using equations by Chen (1972). Nine samples of sulfides and barite were crushed and separated by handpicking under binocular microscope and powdered with agate mortar and pestle. About one gram of each sample was sent to the Stable Isotope and ICP/MS Laboratory of Queen’s University, Canada for sulfur isotope analysis. The sulfur isotopes in sulfides and sulfates were run on a Thermo Finnigan Delta Plus XP IRMS mass spectrometer. The analytical uncertainty for δ34S is ±0.2‰.

Results and Discussion
The main types of fluid inclusions in quartz and calcite are as follows: I: dominant liquid + less vapor (L+V); II: dominant vapor + less liquid (V + L); III: liquid + vapor+ CO2 (L+V+CO2 )(L+V)); IV: CO2 (L+V); V: liquid + vapor + sylvite (L+V+Sy). Homogenization temperatures of primary fluid inclusions indicate that mineralization occurred at temperatures ranging from 130 to 320 °C (ave., 200°C) and their salinites range from 10 to 15 wt % NaCl equiv. The temperatures and salinities of the mineralizing fluids of the Ahangaran deposit are similar to the Irish type Zn-Pb deposits, and suggest a similar origin. The δ34S values of pyrite and galena are within the range of -25.5 to +11.6 ‰ and -6.3 to -8.5 ‰, respectively and for barite are in the range of 26 to 27.2 ‰. These values indicate that the δ34SH2S values of fluids in that deposited the pyrite and galena are within the range of -6.4 to-2.9 ‰ and 9.4 to 27.9 ‰, respectively. The δ34S values of marine sulfate were 13 to 20 ‰ during the Cretaceous (Hoefs, 2009). The δ34S values of barite are near to that of marine sulfate in the Cretaceous which indicate that the sulfate of the barite may have a marine origin. On the other hand, the δ34SH2S values of galena lie within a narrow range, suggesting that the main source of sulfur may be from thermochemical sulfate reduction (TSR).

Acknowledgments
In this research, we thank Sormak Mines Company for its support during field work. We also thank Sormak Mines Managers, especially Mr. Khakbaz for his cooperation and support of this research. Parts of this research were supported by the research department of Bu-Ali Sina University. We also wish to express our appreciation of the isotopic analyses by Queen's University, Canada.

References
Bodnar, R.J. and Vityk, M.O., 1994. Interpretation of microthermometric data for H2O-NaCl fluid inclusion. In: B. De Vivo and M.L. Fezzotti (Editors), Fluid inclusions in minerals, Methods and Applications. Virginia Tech, Blacksburg, pp. 117-130.
Chen, H.S., 1972. The thermodynamics and composition of carbon dioxide hydrate. M.Sc. Thesis, Syracuse University, Syracuse, New York, 67 pp.
Hoefs, J. (translated by Alirezaei, S.), 2009. Stable Isotope Geochemistry. Springer Verlag, Berlin, 332 pp. (in Persian)

385-402

Authors: Alireza Zarasvandi, Babak Samani, Houshang Pourkaseb, Zahra Khorsandi and Yaghoub Jalili

Introduction
Two main principal aspects for the genesis of porphyry copper deposits have been determined. The first genetic model concerns the petrologic and geochemical processes and the other relates the genesis to crustal deformation and geodynamic conditions (Kesler, 1997). Recent studies (e.g., Padilla Garza et al., 2001) show that the generation and emplacement of porphyry copper deposits may not only be dependent on magmatic and hydrothermal processes, but also that the regional and local tectonic setting plays an important role. Therefore in determining the suitable setting for emplacement of copper and other porphyry intrusions, determination of location of partial melting of the lower crust, generation of batholiths, and their volatile-rich derivative intrusions in the crust seems to be necessary (Carranza and Hale, 2002). Almost all porphyry copper deposits in Iran are located in the Urumieh-Dokhtar magmatic belt. These deposits show distinct spatial and temporal relationship with Miocene granodiorite plutonic rocks emplaced along strike slip faults (Mehrabi et al., 2005). Accordingly, the tectonic setting of ore deposits seem to be the most important factor for regional exploration of porphyry copper systems (Vearncombe and Vearncombe, 1999). There are several methods for analysis of distribution of ore deposits. In this research the role of structural control in the spatial distribution of porphyry deposits has been studied using Fry and Fractal methods. Here, the Fry method is used as a complementary method for Fractal analysis.

Materials and methods
Fry analysis is a self-adaptive method that is used for point objects. Fry analysis offers a visual approach to quantify the spatial trends in groups of point objects. Fry analysis can also be used to search for anisotropies in the distribution of point objects. More specifically it can be used to investigate whether a distribution of point objects occurs along linear trends, and whether such linear trends occur at a characteristic spacing. There is 37 and 42 copper point's index in the Khezr-Abad and Shar-B-Babak areas. The Fry patterns of copper index for two areas were determined with application of Dot Proc software. Fractal analysis is another technique for determination of regional distribution of faults. In this research the fractal dimension of joints and faults was determined in different locations using box-counting fractal method and drawing the logarithmic graphs.

Results
- The major faults show NW/SE trends in the Khezr-Abad area. They have a similar trend with Dehshir-Baft fault. Other sets of faults show NE/SW trend. These faults are younger than the Dehshir-Baft and release sinistral sense of shear.
- Intrusion of two intrusive bodies leads to the accumulation of strike-slip faults in the vicinity of intrusive rocks. In this region faults and joints mainly show NW/SE and NE/SW trends.
- The results of Fry analysis show that the mineralization in the Khezr-Abad occurred in the Cretaceous (and younger) rocks with NE/SW and NW/SE orientations. In the other words, these areas of mineralization are mainly related to the secondary faults or (P faults) in the pull basins and cross cutting points of these faults which have similar strike with the Dehshir-Baft fault. NE/SW mineralization is probably related to the tensional stress direction or faults having the general trends of central Iran structures.
- The calculations of fractal dimension show that the southeastern parts of the Khezr Abad have higher amounts of fractal dimension (Db= 1.7002). Also there is a relatively higher copper index in this part, indicating a logical relation between fault structures and mineralization.
-The generated maps indicate that the mineralization in the Shahr-e-Babak area occurred at the intersection of faults and volcanic system and the Fry analysis shows a NE/SW and NW/SE trend of ore concentration.
- Northwestern parts of the Share-e-Babak show higher fractal dimension (Db= 1.748) that occurs in the areas with more volcanic rocks and copper indexes.
- Results show that the porphyry copper mineralization mainly occurs near the great faults and related to the fault structures and shear zones in the Urumieh-Dokhtar structural zone. In the other word fault lineaments are the main factors in the local concentration of the ore deposits.

Discussion
The Study of geometry and mechanism of faults related to porphyry copper deposits is very important for determining the suitable location of ore concentration (Zarasvandi, 2004). For example, shear zones, pull apart basins, and step over along the strike slip faults are proper locations for concentration of porphyry ore deposits (Carranza and Hale, 2002). In this research the Khezr-Abad and Shahr-e-Babak areas have been studied. Plotted rose diagrams show the main role of the Dehshir-Baft shear zone for generating the joints and faults in the KhezrAbad area. In this area faults with NNW/SSE and NW/SE trends are the main direction of ore concentration. They are mainly related to the Dehshir-Baft fault. NE/SW faults show sinistral sense of shear and generally are younger than before mentioned sets. Finally the latest fault sets show N/S trend. The Shahre-e-Babak area is mainly dominated with Eocene igneous rocks. Volumetrically, andesite units are more abundant. Rose diagrams represent the existence of two main conjugate fault sets with NW/SE and NE/SW trends. The main copper indexes are located in the intersection of volcanic rocks with these two fault sets. Also the results of Fractal analyses reveal the higher Fractal dimension in the Northwestern part of the Shahr-e-Babak area. In the other words the most density of joint and faults occurred in this region.

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