Geology and geochemistry of the Choran porphyry-epithermal Cu-Au deposit in the Dehej-Sarduveyeh subzone, Urumieh-Dokhtar magmatic arc

Document Type : Research Article

Authors

1 Professor, Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

2 Ph.D. Student, Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

3 Assistant Professor, Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

4 Associate Professor, Department of Geology, Faculty of Earth Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran

5 Associate Professor, Faculty of Earth Sciences, Shahrood University of Technology, Shahrood, Iran

Abstract

Introduction
Iran hosts numerous porphyry and epithermal ore deposits which have mostly been formed at discrete time periods within different tectonic assemblages. Porphyry and epithermal ore deposits are considered to be the important sources of base metals in Iran. Well-known porphyry deposits include the Sarcheshmeh, Meiduk, Sungun, (Shahabpour and Kramers, 1987; Hezarkhani and Williams, 1998; Taghipour et al., 2008), and well-known epithermal deposits include the Sari Gunay, Chah Zard, Touzlar, and Narbaghi (Richards et al., 2006, Kouhestani et al., 2012, Heidari et al., 2018). The Choran deposit exists in the Urumieh-Dokhtar Magmatic Belt (UDMB). This deposit is located in the southern part of the Cenozoic Urumieh-Dokhtar Magmatic Belt, 70 km SW of Bardsir city, SE Iran. In this area, mineralization is associated with Oligocene - Miocene quartz diorite and granodiorite intrusions emplaced within Eocene volcanic–pyroclastic sequences. This study has focus on the spatial and temporal relationships between the porphyry and epithermal styles of mineralization in this area. 
Materials and methods
A camp was set up in the field and sampling was performed during the 2017-2018. During the field observations, 286 rock samples were collected from the outcrops and drill core, and 67 thin sections were prepared and studied using a polarizing microscope in the Shahid Chamran University of Ahvaz. In order to correctly characterize the chemical composition of silicates (plagioclase and biotite), samples with least traces of alteration have been selected. The chemical composition of plagioclase and biotite were determined on the carbon coated thin section samples using an Electron Probe Micro Analyzer (EPMA). All the analyses were conducted at the Montanuniversitat Leoben, Austria using a superprobe Jeol JXA 8200 instrument.
 
Results
Based on drill core logging and petrographic studies, mineralization in the Choran deposit is mainly accompanied with granodiorite intrusions. Overall, both hypogene and supergene mineralizations have been identified in the study area. The hypogene mineralization mainly occurs as disseminated blebs and veins which consist of pyrite, arsenopyrite and chalcopyrite with minor amounts of sphalerite. The supergene mineralizations that involve chalcocite and covellite. The first generation of hydrothermal veins (A-type) are characterized by assemblages of quartz + K-feldspar ± magnetite occurring roughly in the potassic alteration. This is followed by B-type veins characterized by assemblages of quartz + pyrite + chalcopyrite + feldspar ± biotite ± magnetite ± calcite. Type C veinlets (1 mm to 5 cm width) contain quartz + pyrite ± chalcopyrite and exhibit an intense stockwork texture in the potassic and phyllic alteration zones. The supergene sulfide zone is dominated by chalcopyrites and it is completely or partly replaced by chalcocite, digenite, and covellite. The hydrothermal alteration consisting of sodic-potassic, potassic, phyllic alunite and kaolinite are associated with granodiorite and quartz diorite intrusions. The result of EPMA analyses showed that all of the plagioclases in granodiorite and quartz diorite are consistently of andesine type. Based on the diagram of Al / (Ca + Na + K) (a.p.f.u) vs. An%, (Williamson et al., 2016) plagioclase samples of granodiorite intrusions plot collectively in the field of fertile calc-alkaline rocks associated with porphyry mineralization, while the quartz diorite samples are mostly plotted in the barren field. The results of biotite analyses indicate that all biotites of granodiorite and quartz diorite intrusions are of Mg-biotite type. The amounts of IV (F), IV (Cl), and IV (F/Cl) in the biotites of quartz diorite and granodiorite are between (2.28 to 4.08), (-5.62 to -5.52), (7.87 to 9.64) and (2.03 to 2.45), (- 5.81 to - 5.66), (7.74 to 8.18), respectively.
 
 
Discussion
Most of the characteristics of the Choran Cu-Au deposit, i.e. geological setting, textural and structural, mineralogical with alteration features, are analogous to that of porphyry systems having high-sulphidation epithermal lithocap (Hedenquist et al., 1998; Muntean, 2001; Sillitoe, 2010).
 
Acknowledgements
This research was made possible by a grant (No: SCU.EG98.582) from the office of vice-chancellor for research and technology, Shahid Chamran University of Ahvaz. We acknowledge their support. The fifth author expresses his appreciation to the University of Shahrood Grant Commission for research funding.

Keywords


Ague, J.J. and Brimhall, G.H., 1988. Magmatic arc asymmetry and distribution of anomalous plutonic belts in the batholiths of California: effects of assimilation, cratonal thickness and depth of crystallization. GSA Bulletin, 100(1): 912–927. https://doi.org/10.1130/0016-7606(1988)100<0912:MAAADO>2.3.CO;2
Ahmadian, J., Haschke, M., McDonald, I., Regelous, M., Ghorbani, M., Emami, M. and Murata, M., 2009. High magmatic flux during Alpine–Himalayan collision: constraints from the Kal-e-Kafi complex, central Iran. Geological Society of America Bulletin, 121(5–6): 857– 868. https://doi.org/10.1130/B26279.1
Alavi, M., 1994. Tectonics of the Zagros orogenic belt of Iran: new data and interpretations. Tectonophysics, 229(3–4): 211–238. https://doi.org/10.1016/0040-1951(94)90030-2
Almeev, R.R. and Ariskin, A.A., 1996. Mineralmelt equilibria in a hydrous basaltic system: computer modeling. Geochemistry International, 34(7): 563–573. Retrieved Swptember 1, 1996 from https://www.academia.edu/17785119/MineralMelt_Equilibria_in_a_Hydrous_Basaltic_System_Computer_Modeling
Asadi, S., Moore, F. and Zarasvandi, A., 2014. Discriminating productive and barren porphyry copper deposits in the southeastern part of the central Iranian volcanoplutonic belt, Kerman region, Iran: a review. Earth-Science Reviews, 138(3): 25–46. https://doi.org/10.1016/j.earscirev.2014.08.001
Ayati, F., Yavuz, F., Noghreyan, M., Haroni, H.A. and Yavuz, R., 2008. Chemical characteristics and composition of hydrothermal biotite from the Dalli porphyry copper prospect, Arak, central province of Iran. Mineralogy and Petrolology, 94(1): 107–122. https://doi.org/10.1007/s00710-008-0006-5
Berberian, M. and King, G.C., 1981. Towards a paleogeography and tectonic evolution of Iran. Canadian Journal of Earth Sciences, 18(2): 210–265. https://doi.org/10.1139/e81-019
Berberian, F., Muir, I.D., Pankhurst, R.J. and Berberian, M., 1982. Late Cretaceous and early Miocene Andean-type plutonic activity in northern Makran and Central Iran. Journal of the Geological Society, 139(5): 605–614. https://doi.org/10.1144/gsjgs.139.5.0605
Boomeri M., Nakashima K. and Lentz, DR., 2010. The Sarcheshmeh porphyry copper deposit, Kerman, Iran: A mineralogical analysis of the igneous rocks and alteration zones including halogen element systematic related to Cu mineralization processes. Ore Geology Reviews, 38(5): 367–381. https://doi.org/10.1016/j.oregeorev.2010.09.001
Brimhall, G.H. and Crerar, D.A., 1987. Ore fluids, Magmatic to supergene, in thermodynamic modeling of geological materials. Reviews in Mineralogy and Geochemistry, 17(1): 235–321. https://doi.org/10.1515/9781501508950-010
Chang, Z., Hedenquist, J.W., White, N.C., Cooke, D. R., Roach, M., Deyell, C.L. and Cuison, A. L., 2011. Exploration tools for linked porphyry and epithermal deposits: Example from the Mankayan intrusion-centered Cu-Au district, Luzon, Philippines. Economic Geology, 106(8): 1365–1398. https://doi.org/10.2113/econgeo.106.8.1365
Deer, W.A., Howie, R.A. and Zussman, J., 1992. An Introduction to the Rock Forming Minerals, Second Longman Editions. Longman, London, 696 pp. https://doi.org/10.1180/DHZ
Franchini, M., McFarlane, C., Maydagán, L., Reich, M., Lentz, D.R., Meinert, L. and Bouhier, V., 2015. Trace metals in pyrite and marcasite from the Agua Rica porphyry-high sulfidation epithermal deposit, Catamarca, Argentina: Textural features and metal zoning at the porphyry to epithermal transition. Ore Geology Reviews, 66(3): 366–387. https://doi.org/10.1016/j.oregeorev.2014.10.022
Gregory, M.J., 2017. A fluid inclusion and stable isotope study of the Pebble porphyry copper-gold-molybdenum deposit, Alaska. Ore Geology Reviews, 80(5): 1279–1303. https://doi.org/10.1016/j.oregeorev.2016.08.009
Hedenquist, J., 2000. Exploration for Epithermal Gold deposits. Society of Exploration Geophysicists Reviews, 13(1): 245–277. https://doi.org/10.5382/Rev.13
Hedenquist, J.W., Arribas, A., J.r. and Reynolds, T.J., 1998. Evolution of an intrusion-centered hydrothermal system: Far Southeast-Lepanto porphyry and epithermal Cu-Au deposits, Philippines. Economic Geology, 93(4): 373–404. https://doi.org/10.2113/gsecongeo.93.4.373
Heidari, M., Zarasvandi, A., Rezaei, M., Raith, J. and Saki, A., 2018. Physicochemical Attributes of Parenta Magma in Collisional Porphyry Copper Systems; Using Biotite Chemistry, Case Study: Chahfiruzeh Porphyry Copper Deposit. Journal of Economic Geology, 10(2): 561–586. https://doi.org/10.22067/ECONG.V10I2.65652
Hezarkhani, A. and Williams, A.E., 1998. Controls of alteration and mineralization in the Sungun porphyry copper deposit, Iran: evidence from fluid inclusions and stable isotopes. Economic Geology, 93(5): 651–670. https://doi.org/10.2113/gsecongeo.93.5.651
Hosini, Z., Ghaemi, J. and Mohbi, A., 1994. Geological map of Sirzan, scale 1:250,000. Geological Survey of Iran.
Khan nazer, N.H., 1995. Geological map of Chargonbad, scale 1:100,000. Geological Survey of Iran.
Kirkham, R.V. and Dunne, K.P., 2000. World distribution of porphyry, porphyry-associated skarn, and bulk-tonnage epithermal deposits and occurrences, Natural Resources Canada, Geological Survey of Canada, Open File, Volume 3792, Part 1, 87 pp. https://doi.org/10.4236/ojg.2018.86035
Kouhestani, H., Ghaderi, M., Zaw, Khin., Meffre, S. and Emami, M.H., 2012. Geological setting and timing of the Chah Zard breccia-hosted epithermal gold–silver deposit in the Tethyan belt of Iran. Mineral Deposita, 47(4): 425–440. https://doi.org/10.1007/s00126-011-0382-3
 Lalonde, A.E. and Bernard, P., 1993. Composition and color of biotite from granites: two useful Properties in the characterization of plutonic suites from the Hepburn internal zone of Wopmay orogeny, Northwest Territories. The Canadian Mineralogist, 31(1): 203–217. Retrieved March 03, 1993 from https://pubs.geoscienceworld.org/canmin/article abstract/31/1/203/12452/Composition-and-color-of-biotite-from-granites-two?redirectedFrom=fulltext
Munoz, J.L., 1984. F–OH and Cl–OH exchange in micas withapplications to hydrothermal ore deposits. In: S.W. Bailey (Editor), Micas. Mineralogical Society of America Reviews in Mineralogy, Volune 13, pp. 469–493. Retrieved January 01, 1984 from https://pubs.geoscienceworld.org/canmin/article-abstract/31/1/203/12452/Composition-and-color-of-biotite-from-granites-two?redirectedFrom=fulltext
Muntean. J., 2001. Porphyry-Epithermal Transition: Maricunga Belt, Northern Chile. Economic Geology, 96(4): 743–772. https://doi.org/10.2113/gsecongeo.96.4.743
Nachit, H., Ibhi, A.B., Abia, El-H., El Hassan, A. and Ben Ohoud, M., 2005. Discrimination between primary magmatic biotites, reequilibrated biotites, and neoformed biotites. Comptes Rendus Geoscience, 337(16): 1415–1420. https://doi.org/10.1016/j.crte.2005.09.002
Pletchov, P.Y. and Gerya, T.V., 1998. Effect of H2O on plagioclase-melt equilibrium. Experiment in Geosciences, 7(2): 7–9. https://doi.org/10.2138/am.2012.4100
Pourkaseb, H., Zarasvandi1, A., Saed, S. Davoudian Dehkordy, A., 2017. Magmatic-hydrothermal fluid evolution of the Dalli porphyry Cu-Au deposit; using Amphibole and Plagioclas mineral chemistry. Journal of Economic Geology, 9(1): 73–92. (in Persian with English abstract)  https://doi.org/10.22067/ECONG.V9I1.51704
Putirka, K.A., 2005. Igneous thermometers and barometers based on plagioclase plus liquid equilibria: tests of some existing models and new calibrations. American Mineralogist, 90(2–3): 336–346. https://doi.org/10.2138/am.2005.1449
Richards, J.P., Spell, T., Rameh, E., Razique, A. and Fletcher, T., 2012. High Sr/Y magmas reflect arc maturity, high magmatic water content, and porphyry Cu ± Mo ± Au potential: examples from the Tethyan arcs of Central and Eastern Iran and Western Pakistan. Economic Geology, 107(3): 295–332. https://doi.org/10.2113/econgeo.107.2.295
Richards, J.P., Wilkinson, D. and Ullrich, T., 2006. Geology of the Sari Gunay epithermal gold deposit, northwest Iran. Economic Geology, 101(8): 1455–1496. https://doi.org/10.2113/econgeo.107.2.295
Shafiei, B., 2012. Discrimination between productive and non-productive granitoid intrusions in Kerman porphyry copper belt: Results of preliminary petrographic studies. Journal of Advanced Applied Geology, 2(1): 1–7. Retrieved August 01, 2012 from https://aag.scu.ac.ir/article_11549.html?lang=en
Shafiei, B., Haschke, M. and Shahabpour, J., 2009. Recycling of orogenic arc crust triggers porphyry Cu mineralization in Kerman Cenozoic arc rocks, southeastern Iran. Mineralium Deposita, 44(3): 265–281. https://doi.org/10.1007/s00126-008-0216-0
Shafiei, B. and Shahabpour, J., 2008. Gold distribution in porphyry copper deposits of Kerman region, Southeastern Iran. Journal of Sciences, Islamic Republic of Iran, 19(3): 247–260. Retrieved November 01, 2008 from https://jsciences.ut.ac.ir/article_31898_d85486b4c0968032c431d13c3a137f20.pdf
Shahabpour, J. and Kramers, J.D., 1987. Lead isotope data from the Sar-Cheshmeh porphyry copper deposit, Iran. Mineralium Deposita, 22(4): 278–281. https://doi.org/10.1007/BF00204520
Sillitoe, R.H., 2010. Porphyry copper systems. Economic Geology, 105(1): 3–41. https://doi.org/10.2113/gsecongeo.105.1.3
Taghipour, N., Aftabi, A. and Mathur, R., 2008. Geology and Re-Os Geochronology of Mineralization of the Miduk Porphyry Copper Deposit, Iran. Resource Geology, 58(18): 143–160. https://doi.org/10.1111/j.1751-3928.2008.00054.x
Takin, M., 1972. Iranian geology and continental drift in the Middle East. Nature, 235(53): 147–150. https://doi.org/10.1038/235147a0 
Teiber, H., Scharrer, M., Marks, M.A.W., Arzamastsev, A.A., Wenzel, T. and Markl, G., 2015. Equilibrium partitioning and subsequent re-distribution of halogens among apatite–biotite–amphibole assemblages from mantle-derived plutonic rocks. Complexities revealed. Lithos, 220(223): 221–237. https://doi.org/10.1016/j.lithos.2015.02.015
Tischendorf, G., Gottesmann, B., Förster, H.J. and Trumbull, R.B., 1997. On Li-bearing micas: Estimating Li from electron microprobe analyses and an improved diagram for graphical representation. Mineralogical Magazine, 61(1): 809–834. https://doi.org/10.1180/minmag.1997.061.409.05
Whitney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-formingminerals. American Mineralogist, 95(1): 185-187. https://doi.org/10.2138/am.2010.3371
Williamson, B.J., Herrington, R.J. and Morris, A., 2016. Porphyry copper enrichment linked to excess aluminium in plagioclase. Nature Geoscience, 9(3): 237–241. https://doi.org/10.1038/ngeo2651
Willmore, C.C., Boudreau, A.E. and Kruger, F.J., 2000. The halogen geochemistry of the Bushveld Complex, Republic of South Africa: implications for chalcophile element distribution in the lower and critical zones. Journal of Petrology, 41(10): 1517–1539. https://doi.org/10.1093/petrology/41.10.1517
Yavuz, F., 2003. Evaluating micas in petrologic and metallogenic aspect: Part II – Applications using the computer program Mica+. Computers and Geosciences, 29(10): 1215–1228. https://doi.org/10.1016/S0098-3004(03)00143-2
Zarasvandi, A., Liaghat, S. and Zentilli, M., 2005. Geology of the Darreh-Zerreshk and Ali-Abad porphyry copper deposits, central Iran. International Geology Review, 47(6): 620–646. https://doi.org/10.2747/0020-6814.47.6.620
Zarasvandi, A., Rezaei, M., Raith, J.G., Pourkaseb, H., Asadi, S., Saed, M. and Lentz, D.R., 2018. Metal endowment reflected in chemical composition of silicates and sulfides of mineralized porphyry copper systems, Urumieh-Dokhtar magmatic arc, Iran. Geochimica et Cosmochimica Acta, 223(36): 36–59. https://doi.org/10.1016/j.gca.2017.11.012
CAPTCHA Image