Hydrothermal Fluid evolution in the Dalli porphyry Cu-Au Deposit: Fluid Inclusion microthermometry studies

Document Type : Research Article

Authors

• Alireza Zarasvandi ¹
• Fateme Asadi ¹
• Houshang Pourkaseb ¹
• Farhad Ahmadnejad ²
• Hassan Zamanian ²

¹ Shahid Chamran University of Ahvaz

² Lorestan

10.22067/econg.v7i2.38447

Abstract

Introduction
A wide variety of world-class porphyry Cu deposits occur in the Urumieh-Dohktar magmatic arc (UDMA) of Iran.The arc is composed of calc-alkaline granitoid rocks, and the ore-hosting porphyry intrusions are dominantly granodiorite to quartz-monzonite (Zarasvandi et al., 2015). It is believed that faults played an important role in the emplacement of intrusions and subsequentporphyry-copper type mineralization (Shahabpour, 1999). Three main centers host the porphyry copper mineralization in the UDMA: (1) Ardestan-SarCheshmeh-Kharestan zone, (2) Saveh-Ardestan district; in the central parts of the UDMA, hosting the Dalli porphyry Cu-Au deposit, and (3) Takab-Mianeh-Qharahdagh-Sabalan zone. Mineralized porphyry coppersystems in the UDMA are restricted to Oligocene to Mioceneintrusions and show potassic, sericitic, argillic, propylitic and locally skarn alteration (Zarasvandi et al., 2005; Zarasvandi et al., 2015). In the Dalli porphyry deposit, four hydrothermal alteration zones, includingpotassic, sericitic, propylitic, and argillic types have been described in the two discrete mineralized areas, namely, northern and southern stocks. Hypogenemineralization includes chalcopyrite, pyrite, and magnetite, with minor occurrences of bornite.Supergene activity has produced gossan, oxidized minerals and enrichment zones. The supergene enrichment zone contains chalcocite and covellite with a 10-20 m thickness. Mineralization in the northern stock is mainly composed of pyrite and chalcopyrite. The aim of this study is the investigation and classification of hydrothermal veins and the constraining of physicochemical compositions of ore-forming fluids using systematic investigation of fluid inclusions.

Materials and methods
Twenty samples were collected from drill holes. Thin and polished sections were prepared from hydrothermal veins of thepotassic, sericitic and propylitic alteration zones. Samples used for fluid inclusion measurements were collected from drill cores DH01, DH02, DH06, and DH07, and outcrop samples. Microthermometric data were obtained by freezing and heating of fluid inclusions on a Linkam THMSG600 mounted on an Olympus microscope at Lorestan University.

Results
1) Five main veintypes were identified, belonging to three stages of mineralization:type (I): barren quartz, type (II): quartz + pyrite + chalcopyrite ± bornite ± chalcocite ± covelite, type (III): quartz + magnetite ± chalcopyrite, type (IV): K-feldspar± quartz ± chalcopyrite, type (V): chlorite + biotite.
2) Seven groups of fluid inclusionswere observed: (IA) liquid-rich mono-phase, (IB) vapor-rich mono-phase, (IIA) liquid-rich two-phase (liquid + vapor), (IIB) vapor-rich two-phase (vapor + liquid), (IIIA) high salinity simple fluids (liquid + vapor + halite), (IIIB) high salinity opaque mineral-bearing fluids (liquid + vapor + halite + pyrite + chalcopyrite + hematite), (IIIAB) multi-phase fluids (liquid + vapor + halite + sylvite + hematite + magnetite + pyrite + chalcopyrite ± erythrosiderite)
3) Multiphase fluid inclusions with predominant homogenization temperatures 420 to 620˚C and predominant salinities 70 to 75 wt.%NaCl, are thought to be the early fluids involved in mineralization.
4) The coexistence of high saline liquid and vapor rich fluid inclusions (IIIAB, IIIB, IIIA and IIA types) resulted either from fluid entrapment during the boiling process or the co-presence of two immiscible fluids generated from the magma.
5) Dalliporphyry Cu-Au deposit was formed in a magmatic-meteoric system.

Discussion
Two conventional thermometric procedures, freezing and heating, were employed for the measurement of temperature of homogenization and approximate salinity. Freezing was conducted mainly for halite-under saturated inclusions (types IIA and IIB), to measure the initial melting temperature (Te) and the last melting point (Tmice), whereas heating was carried out on the halite-bearing inclusions (types IIIA, IIIB and IIIAB). Based on the microthermometric results, the Dalli fluid inclusions can be divided into two distinct groups: (1) medium-high temperature, hypersaline (Types IIIA, IIIB and IIIAB) and (2) low-medium temperature, low salinity group (Types IIA and IIB). Type IIB inclusions, which homogenize to the vapor phase and have a relatively low cooling rate, provide a fairly good estimate of entrapment pressure (Roedder and Bodnar, 1980). Based on the pressure estimated for the Dalli deposit, mineralization likely occurred at depth of 0.6-1.1 km. The calculated depth is coincident with the estimated mineralization depths of the porphyry deposits in the world (Pirajno, 2009). Fluid inclusions with a wide range of vapor and liquid ratios are abundant in all of the Dalli samples. This represents heterogeneous trapping of liquid and vapor. The coexistence of inclusions with different volumes of vapor contents, which homogenize either to liquid (Th(L-V)) or vapor (Th(V-L)), are interpreted as an evidence for the prevailing wide range of physico-chemical conditions during the cooling history of ore-forming fluid at the Dalliporphyry Cu-Au deposit. The boiling process is documented by the abundance of heterogeneously trapped fluid inclusions with extremely variable liquid to vapor ratios (Ahmad and Rose, 1980).

Acknowledgements
We thank of ShahidChamran University of Ahvaz for their support and moreover, Lorestan University for microthermometric studies.

References
Ahmad, S.N. and Rose, A.W., 1980. Fluid inclusions in porphyry and skarn ore at Santa Rita, New Mexico. Economic Geology, 75(3): 229–250.

Pirajno, F., 2009. Hydrothermal processes and mineral systems. Geological Survey of Western Australia. Springer, 1250 pp.

Roedder, E. and Bodnar R.J., 1980. Geologic pressure determinations from fluid inclusion studies, Annu. Review Earth Planet, 8(6): 263–301.

Shahabpour, J., 1999. The role of deep structures in the distri bution of some major ore deposits in Iran, NE of the Zagros thrust zone. Journal of Geodynamics, 28(3): 237-250.

Zarasvandi, A., Liaghat, S. and Zentilli, M., 2005. Porphyry Copper Deposits of the Urumieh-Dokhtar Magmatic Arc, Iran, Super Porphyry Copper and Gold deposits. A global perspective PGC publishing Adelaide, 2(4): 441-452.

Zarasvandi, A., Rezaei, M., Sadeghi, M., Lentz, D., Adelpour, M. and Pourkaseb, H., 2015. Rare earth element signatures of economic and sub- economic porphyry copper systems in Urumieh–Dokhtar Magmatic Arc (UDMA), Iran. Ore Geology Reviews, 70(3): 407-423.

Keywords

• magmatic arc
• Dalli
• hydrothermal
• Alteration
• porphyry Cu-Au
• fluid inclusion

20.1001.1.20087306.1394.7.2.6.0

---

References

Afshooni, S.Z., Mirnejad, H., Esmaeily, D. and Asadi, H.H., 2013. Mineral chemistry of hydrothermal biotite from the Kahang porphyry copper deposit (NE Isfahan), Central Province of Iran. Ore Geology Reviews, 54(1): 214–232.

Ahmad, S.N. and Rose, A.W., 1980. Fluid inclusions in porphyry and skarn ore at Santa Rita, New Mexico. Economic Geology, 75(3): 229–250.

Ahmadian, J., Haschke, M., McDonald, I., Regelous, M., Ghorbani, M., Emami, R. 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.

Alfons, M., Kerkhof, V. and Ulrich, F.H., 2001. Fluid inclusion petrography. Lithos, 55(1-4): 27–47.

Alizadeh, S.B. and Hezarkhani, A., 2014. Hydrothermal evolution of Darrehzar porphyry copper deposit, Iran: evidence from fluid inclusions. Arabian Journal of Geoscienes, 7(4): 1463–1477.

Asadi, S., Moore, F. and Fattahi, N., 2012. Fluid inclusion and stable isotope constraints on the genesis of the Jian copper deposit, Sanandaj-Sirjan metamorphic zone, Iran. Geofluids, 13(1): 66-81.

Asadi, S., Moore, F., Zarasvandi, A. and Khosrojerdi, M., 2013. First report on the occurrence of CO2-Bearing fluid inclusions in the Meiduk porphyry copper deposit, Iran: implications for mineralization processes in a continental collision setting. Geologos, 19(4): 301-320.

Asadi Haroni, H., 2008. First Stage Drilling Report on (Dalli Porphyry Cu-Au Prospect, Central Province of Iran). Technical of Iran, Isfahan, Report 1, 24 pp.

Asadi Haroni, H., Fathianpour, N., Tabatabai, H. and Heydari, E., 2009. Final report of exploratory processing in (Dalli Cu-Au deposite). Industry and Mines Organization of Markazi province, Arak, Report 4, 157 pp.

Ayati, F., Yavuz, F., Asadi, H.H., Jeremy, P. and Jourdan, R., 2013. Petrology and geochemistry of calc-alkaline volcanic and subvolcanic rocks, Dalli porphyry copper–gold deposit, Markazi Province, Iran. International Geology Review, 55(2): 158-184.

Ayati, F., Yavuz, F., Noghreyan, M., Asadi, H.H. and Yavuz, R., 2008. Chemical characteristics and composition of hydrothermal biotite from the Dalli porphyry copper prospect, Arak, central province of Iran. Miner Petrology, l 94(1-2): 107-122.

Bodnar, R.J., 1993. Revised equation and table for determining the freezing point depression of H2O-NaCl solutions. Geochimistry, 57(3): 683–684.

Bodnar, R.J., 2003. Reequilibration of fluid inclusions, in Samson. Geological Associa-tion of Canada short course series, 32(3-4): 213–231.

Burnham, C.W., 1985. Energy release in subvolcanic environments: implications for breccia formation. Economic Geolology, 80(6): 515–522.

Calagari, A.A., 2004. Fluid inclusion studies in quartz veinlets in porphyry copper deposit at Sungun, East – Azarbaidjan, Iran. Journal of Asian Earth Sciences, 23(2): 179-189.

Cline, J.S. and Bodnar, R.J., 1991. Can economic porphyry copper mineralization be generated by a typical calc-alkaline melt. Geophysics, 96(5): 8113–8126.

Cline, J.S. and Bodnar, R.J., 1994. Experimental determination of the PVTX properties of 30 wt% NaCl-H2O using synthetic fluid inclusions. Geophysics, 57(5): 4230–4236.

Cooke, D.R., Hollings, P. and Walshe, J.L., 2005. Giant Porphyry Deposits: Characteristics, Distribution, and Tectonic Control. Economic Geology, 100(5): 801-818.

Cunningham, C.G., 1978. Pressure gradients and boiling as mechanisms for localizing ore in porphyry systems. Journal of Research of the US Geological Survey, 6(6): 745-754.

Daneshjou, M., 2014. Investigation of Geology, Geochemistry and genetic model of the Dalli Cu-Au porphyry deposit, Delijan, Markazi province. M.Sc. Thesis, Shahid Chamran University, Ahvaz, Iran, 141 pp. (in Persian with English abstract)

Darabi, G.F., Ghavami, R.R. and Asadi, H.H., 2013a. Alteration, zoning model, and mineralogical structure considering lithogeochemical investigation in Northern Dalli Cu–Au porphyry. Geosciences, 6(12): 4821-4831.

Darabi, G.F., Ghavami, R.R., Khalo, K.R., Asadi, H.H. and Seyedrahimi, N.M., 2013b. Interpretation of lithogeochemical and geophysical data to identify the buried mineralized area in Cu-Au porphyry of Dalli-Northern Hill. Arabian Journal of Geoscienes, 6(11): 4499-4509.

Drummond, S.E. and Ohmoto, H., 1985. Chemical evolution and mineral deposition in boiling hydrothermal systems. Economic Geology, 80(1): 126-147.

Emami, M.H., 1991. Explanatory text of the Qom, Geological Quadrangle Map, scale 1:250,000. Geological Survey of Iran.

Forster, H., 1978. Mesozoic- Cenozoic Metallogenesis in Iran. Geological Society, 135(4): 443-455.

Ghorbani, M.R. and Bezenjani, R.N., 2011. Slab partial melts from the metasomatizing agent to adakite, Tafresh Eocene volcanic rocks, Iran, Island Arc. Economic Geology, 20(2): 188-202.

Gustafson, L.B. and Hunt, J.P., 1975. The porphyry copper deposit at El Salvador, Chile. Economic Geology, 70(2): 857−912.

Hezarkhani, A., 2005. Mineralogy and fluid inclusion investigations in the Reagan Porphyry System, Iran, the path to an uneconomic porphyry copper deposit. Journal of Asian Earth Sciences, 27(5): 1–15.

Hezarkhani, A., 2006. Hydrothermal evolution of the Sar-Cheshmeh porphyry Cu–Mo deposit, Iran: Evidence from fluid inclusions. Journal of Asian Earth Sciences, 28(4-6): 409–422.

Hezarkhani, A., 2009. Hydrothermal fluid geochemistry at the Chah-Firuzeh porphyry Copper deposit, Iran: Evidence from fluid inclusions. Journal of Geochemical Exploration, 101(3): 254-264.

John, D.A., Ayuso, R.A., Barton, M.D., Blakely, R.J., Bodnar, R.J., Dilles, J.H., Gray, F., Graybeal, F.T., Mars, J.C., McPhee, D.K., Seal, R.R., Taylor, R.D. and Vikre, P.G., 2010. Porphyry Copper Deposit Model. Scientific Investigations Report, USGS, 169 pp.

Liu, J., Wu, G., Li, Y., Zhu, M. and Zhong, W., 2012. Re–Os sulfide (chalcopyrite, pyrite and molybdenite) systematics and fluid inclusion study of the Duobaoshan porphyry Cu (Mo) deposit, Heilongjiang Province, China. Journal of Asian Earth Sciences, 49(3): 300–312.

Masterman, G.J., Cooke, D.R., Berry, R.F., Walshe, J.L., Lee, A.W. and Clark, A.H., 2005. Fluid chemistry, structural setting, and emplacement history of the Rosario Cu-Mo porphyry and Cu-Ag-Au epithermal veins, Collahuasi district, northern Chile. Economic Geology, 100(2): 835−862.

Mohajjel, M. and Proohan, N., 2005. Geometry and kinematics of the Qom-Zefreh fault system and its significence in transpression tectonics. Geoscienes, 12(56): 72-83.

Morales, S.R., Both, R.A. and Golding, S.D., 2002. A fluid inclusion and stable isotope study of the Moonta copper–gold deposits, South Australia: evidence for fluid immiscibility in a magmatic hydrothermal system. Geology, 192(3-4): 211–226.

Nateghi, A. and Hezarkhani, A., 2013. Fluid inclusion evidence for hydrothermal fluid evolution in the Darreh-Zar porphyry copper deposit, Iran. Journal of Asian Earth Sciences, 73(2-3): 240–251.

Nuo, Li., Ulrich, T., Chen, Y.J., Thomsen, T.B., Pease, V. and Pirajno, F., 2012. Fluid evolution of the Yuchiling porphyry Mo deposit, East Qinling, China. Ore Geology Reviews, 48(4): 442–459.

Pirajno, F., 2009. Hydrothermal processes and mineral systems. Geological Survey of Western Australia. Springer, 1250 pp.

Pollard, P.J. and Taylor, R.G., 2002. Paragenesis of the Grasberg Cu-Au deposit, Irian Jaya, Indonesia: Results from logging section 13. Mineralium Deposita, 37(1): 117−136.

Richards, J.P., 2003. Tectono-Magmatic Precursors for Porphyry Cu-(Mo-Au) Deposit Formation. Economic Geology, 98(8): 1515-1533.

Roedder, E. and Bodnar R.J., 1980. Geologic pressure determinations from fluid inclusion studies, Annu. Review Earth Planet, 8(6): 263–301.

Rusk, B.G., Reed, M.H., 2008. Fluid Inclusion Evidence for Magmatic-Hydrothermal Fluid Evolution in the Porphyry Copper-Molybdenum Deposit at Butte, Montana. Economic Geology, 103(2): 307–334.

Saremi, F., 2014. Hydrothermal alteration mapping using combination of the ASTER data and spectroscopic minerals in the Dalli porphyry Cu-Au deposit, Delijan, Markazi province. M.Sc. Thesis, Shahid Chamran University, Ahvaz, Iran, 142 pp. (in Persian with English abstract)

Shafiei, B. and Shahabpour, J., 2008. Gold Distribution in Porphyry Copper Deposits of Kerman Region, Southeastern Iran. Journal of Sciences, 19(4): 247-260.

Shahabpour, J., 1999. The role of deep structures in the distri‌bution of some major ore deposits in Iran, NE of the Zagros thrust zone. Journal of Geodynamics, 28(3): 237-250.

Shahabpour, J., 2005. Tectonic evolution of the orogenic belt in the region located between Kerman and Neyriz. Journal of Asian Earth Sciences, 24(4): 405-417.

Shahabpour, J., 2007. Island-arc affinity of the central Iranian Volcanic Belt. Journal of Asian earth sciences, 30(5-6): 652-665.

Shelton, K.L., 1983. Composition and origin of ore-forming fluids in a carbonate-hosted porphyry copper and skarn deposit, a fluid inclusion and stable isotope study of Mines Gaspe Quebec. Economic Geology, 78(8): 387–421.

Shen, P., Shen, Y., Wang, J., Zhu, H., Wang, L. and Meng, L., 2010. Methane-rich fluid evolution of the Baogutu porphyry Cu–Mo–Au deposit, Xinjiang, NW China. Chemical Geology, 275(1-2): 78–98.

Siahcheshm, K., Calagari, A.A. and Abedini, A., 2014. Hydrothermal evolution in the Maher-Abad porphyry Cu–Au deposit, SW Birjand, Eastern Iran: Evidence from fluid inclusions. Ore Geology Reviews, 58(5): 1–13.

Sillitoe, R.H., 1979. Some Thoughts on Gold-Rich Porphyry Copper Deposits. Mineral Deposita, 14(2): 161-174.

Sillitoe, R.H., 2010. Porphyry Copper Systems. Economic Geology, 105(3): 3-41.

Spencer, R.J., Moleller, N. and Weare, J.H., 1990. The prediction of mineral solubilities in natural waters: a chemical equilibrium model for the Na-K-Ca-Ma-Cl-SO4-H2O-system at temperatures below 25°C. Geochimistry, 54(5): 575–590.

Sterner, S.M., Hall, D.L. and Bodnar, R.J., 1988. Synthetic fluid inclusions V, Solubility relations in the system NACl-KCl-H20 under vapor-saturated conditions. Geochimistry, 52(2-3): 989–1005.

Stocklin, J. and Setudinia, A., 1972. Location map of the Dalli deposit, scale 1:100,000. Geological Survey of Iran.

Ulrich. T., Gunther, D. and Heinrich, C.A., 2002. The Evolution of a porphyry Cu-Au deposites, Based on LA-ICP-MS Analysis of Fluid Inclusions: Bajo de la Alumbrera. Economic Geology, 96(4): 1743-1774.

Verdel, C., Wernicke, B.P., Hassanzadeh, J. and Guest, B., 2011. A Paleogene extensional arc flare-up in Iran. Tectonics, 30(5): 421-454.

Wilkinson, J.J., 2001. Fluid inclusions in hydrothermal ore deposits. Lithos, 55(3-4): 229-272.

Wilson, J.W., Kesler, S.E., Cloke, P.L. and Kelley, W.C., 1980. Fluid inclusion geochemistry of the Granisle and Bell porphyry copper deposits, British Columbia. Economic Geology, 75(2): 45–61.

Yong, F.Y., Li, N. and Chen, Y.J., 2012. Fluid inclusion study of the Nannihu giant porphyry Mo–W deposit, Henan Province, China: Implications for the nature of porphyry ore- fluid systems formed in a continental collision setting. Ore Geology Reviews, 46(3): 83–94.

Zarasvandi, A., Liaghat, S., Lentz, D. and Hossaini, M., 2013. Characteristics of Mineralizing Fluids of the Darreh-Zerreshk and Ali-Abad Porphyry Copper Deposits, Central Iran, Determined by Fluid Inclusion Microthermometry. Resource Geology, 63(2): 188–209.

Zarasvandi, A., Liaghat, S. and Zentilli, M., 2005. Porphyry Copper Deposits of the Urumieh-Dokhtar Magmatic Arc, Iran, Super Porphyry Copper and Gold deposits. A global perspective PGC publishing Adelaide, 2(4): 441-452.

Zarasvandi, A., Liaghat, S., Zentilli, M. and Reynolds, P.H., 2007. 40Ar/39Ar Geochronology of Alteration and Petrogenesis of Porphyry Copper-Related Granitoids in the Darreh-Zerreshk and Ali-Abad area, Central Iran. Exploration and Mining Geology, 16(2-3): 11–24.

Zarasvandi, A., Rezaei, M., Sadeghi, M., Lentz, D., Adelpour, M. and Pourkaseb, H., 2015. Rare earth element signatures of economic and sub- economic porphyry copper systems in Urumieh–Dokhtar Magmatic Arc (UDMA), Iran. Ore Geology Reviews, 70(3): 407-423.