Fluid inclusion and sulfur stable isotope evidence for the origin of the Ahangran Pb-Ag deposit

Document Type : Research Article

Authors

• Mohammad Maanijou
• Masoumeh Vafaeizad
• Farhad Aliani

Bu-Ali Sina

10.22067/econg.v7i2.25816

Abstract

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)

Keywords

• Pb-Ag
• fluid inclusion
• Sulfur stable isotopes
• Irish type

20.1001.1.20087306.1394.7.2.9.3

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References

Aghanabati, A., 2006. The Geology of Iran. Geological Survey of Iran, Tehran, 707 pp. (in Persian)

Ahmad, S.N. and Rose, A.W., 1980. Fluid inclusions in porphyry and skarn ores at Santa Rita, New Mexico. Economic Geology, 75(2): 229-250.

Anderson, G.M., 2008. The mixing hypothesis and the origin of Mississipi Valley-type ore deposits. Economic Geology, 103(8): 1683-1690.

Anderson, R., Graham, G.M., Royce, A.J. and Fallic, A.E., 2004. Metamorphic and basin fluids in quartz-carbonate-sulphide veins in the SW Scottish Highlands, a stable isotope and fluid inclusion study. Geofluids, 4(2): 85-169.

Bäuerle, G., Bornemann, O., Mauthe, F. and Michalzik, D., 2000. Origin of stylolites in Upper Permian Zechstein anhydrite (Gorleben Salt Dome, Germany). Journal Sedimentary Research, 70(3): 726-737.

Bodnar, R., 1983. A method of Calculating fluid inclusion volumes based on vapor bubble diameters and P-V-T-X properties of inclusion fluid. Economic Geology, 78(3): 535-542.

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.

Boni, M., Balassone, G. and Iannace, A., 1996. Base metal ores in the Lower Paleozoic of southwestern Sardinia. In: D.F. Sangster (Editor), Carbonate-hosted Lead–Zinc Deposits. Society of Economic Geologist Special Publication, Michigan 4, pp. 18–28.

Burruss, R.C., 1981. Analysis of phase equilibria in C-O-H-S fluid inclusions. In: L.S. Hollister and M.L. Crawford (Editors), Mineralogical Association of Canada Short Course in Fluid Inclusion: Applications to Petrology. Royal Ontario Museum, Toronto 6, pp. 39-74.

Calagari, A.A., 2003. Stable isotope (S, O, H and C) studies of the phyllic and potassic–phyllic alteration zones of the porphyry copper deposit at Sungun, East Azarbaidjan, Iran. Journal of Asian Earth Sciences, 21(7): 767–780.

Chen, H.S., 1972. The thermodynamics and composition of carbon dioxide hydrate. M.Sc. Thesis, Syracuse University, Syracuse, New York, 67 pp.

Collins, P.L.F., 1979. Gas hydrates in CO2-bearing fluid inclusions and the use of freezing data for estimation of salinity. Economic Geology, 74(6): 1435-1444.

Conrad, M.E., Petersen, U. and O, Neil, J.R., 1992. Evolution of an Au-Ag producing hydrothermal system: the Tayoltita mine, Durango, Mexico. Economic Geology, 87(6): 1451-1474.

Diamond, L.W., 1994. Salinity of multivolatile fluid inclusions determined from clathrate hydrate stability. Geochimica et Cosmochimica Acta, 58(1): 19-41.

Eldridge, C.S., Williams, N. and Walshe, J.L., 1993. Sulfur isotope variability in sediment-hosted massive sulfide deposits as determined using the ion microprobe shrimp shrimp: II. A study of the HYC deposit at McArtur River, Northern Territory, Australia. Economic Geology, 88(1): 1-26.

Flugel, E., 2004. Microfacies of Carbonate Rocks. Springer-Verlag, Germany, 976 pp.

Giuliani, G., Cheilletz, A., Arboleda, C., Carrillo, V., Rueda, F. and Baker, J.H., 1995. An evaporitic origin of the parent brines of Colombian emeralds: fluid inclusion and sulphur isotope evidence. European Journal of Mineralogy, 7(1): 151-165.

Guilbert, J.M. and Park, C.F., 1986. The geology of ore deposits. William H. Freeman and Company, New York, 985 pp.

Haas, J. L., 1971. The effect of salinity on the maximum thermal gradient of a hydrothermal system in hydrostatic pressure. Economic Geology, 66(6): 940-946.

Hedenquist, J.W. and Henley, R.W., 1985. The importance of CO2 on freezing point measurements of fluid inclusion, Evidence from active geothermal systems and implications for epithermal ore deposition. Economic Geology, 80(5): 1379-1406.

Hitzman, M.W. and Beaty, D.W., 1996. The Irish Zn–Pb–(Ba) orefield. In: D.F. Sangster (Editor), Carbonate-Hosted Lead–Zinc Deposits. Society of Economic Geologist Special Publication, Michigan 4, pp. 112-143.

Hoefs, J., 1997. Stable Isotope Geochemistry. Springer, NewYork, 201 pp.

Hoefs, J., 2004. Stable Isotope Geochemistry. Springer Verlag, Berlin, 244 pp.

Hoefs, J. (translated by Alirezaei, S.), 2009. Stable Isotope Geochemistry. Springer Verlag, Berlin, 332 pp. (in Persian)

Jafarian, B. and Zamani, P., 2006. Geological map of Malayer, scale 1:100,000. Geological Survey of Iran, Tehran, 707 pp. (in Persian)

Kesler, S.E., 1996. Appalachian Mississippi valley-type deposits: paleoaquifers and brine provinces. In: D.F. Sangster (Editor), Carbonate-Hosted Lead–Zinc Deposits. Society of Economic Geologist Special Publication, Michigan 4, pp. 29-57.

Kesler, S.E., 2005. Ore-Forming Fluids. Elements, 1(1): 13-18.

Koptagel, O., Ulusoy, U. and Efe, A., 2005. A study of sulphur isotopes in determining the genesis of Goynuk and Celaldagi Desandre Pb–Zn deposits, eastern Yahyali, Kayseri, Central Turkey. Journal of Asian Earth Sciences, 25(2): 279-289.

Li, Y.B. and Liu, J.M., 2006. Calculation of sulfur isotope fractionation in sulfides. Geochimica et Cosmochimica Acta, 70(7): 1789-1795.

Momenzadeh, M., 1988. The exploration of Ahangaran deposit, phase one, with 1:5000 and 1:1000 geological map. Ministry of Mines and Metals, Tehran, 107 pp. (in Persian with English abstract)

Momenzadeh, M., Shafighi, S., Rastad, E. and Amstutz, G.C., 1979. The Ahangaran lead-silver Deposits, SE-Malayer, west central Iran. Mineralium Deposita, 14(3): 323-341.

Ohmoto, H., 1972. Systematics of sulfur and carbon isotopes in hydrothermal ore deposits. Economic Geology, 67(4): 551-579.

Ohmoto, H. and Goldhaber, M.B., 1997. Sulfur and carbon isotopes. In: H.L. Barnes (Editor), Geochemistry of Hydrothermal Ore Deposits. John Wiley and Sons, New York, pp. 517-611.

Ohmoto, H. and Rye, R.O., 1979. Isotope of sulfur and carbon. In: H.L. Barnes (Editor), Geochemistry of Hydrothermal Ore Deposits. John Wiley and Sons, New York, pp. 509-567.

Pirajno, F., 2009. Hydrothermal processes and mineral system. Springer Science, New York, 1273 pp.

Ramdohr, P., 1980. The ore mineral and their intergrouth. Pergoman press, Berlin, 1207 pp.

Ranjbaran, M., 1991. Sedimentary environment and diagenesis of carbonate rocks containing lead and zinc in Ahangaran mine, Malayer. M.Sc. Thesis, Tehran University, Tehran, Iran, 137 pp. (in Persian with English abstract)

Roedder, E., 1963. Studies of fluid inclusions Π: freezing data and their interpretation. Economic Geology, 58(2): 167-211.

Roedder, E., 1976. Fluid inclusion evidence on the genesis of ores in sedimentary volcanic rocks. In: K.H. Wolf (Editor), Hanndbook of strata- bound and stratiform ore deposits, Geochemical studies. Elsevier, Amsterdam, 2, pp. 67-110.

Rollinson, H.R., 1995. Using Geochemical Data: Evaluation, Presentation and Interpretation. Longman Group, United Kingdom, 344 pp.

Rouxel, O., Shanks, W.C., Bach, W. and Edwards, K.J., 2008. Integrated Fe and S isotope study of seafloor hydrothermal vents at East Pacific Rise 9–10 N. Chemical Geology, 252(3-4): 214-227.

Samson, I., Anderson, A. and Marshall, D., 2003. Fluid Inclusion: Analysis and Interpretation. Mineralogical Association of Canada Short Course 32, Vancouver, 374 pp.

Scott, A.M. and Watanabe, Y., 1988. Extreme boiling model for variable salinity of the Hokko low-sulphidation epithermal gold prospect, south-western Hokkaido, Japan. Mineralium Deposita, 33(6): 568-578.

Simmons, S.F. and Browne, P.R.L., 1997. Saline fluid inclusions in sphalerite from the Broalands-Ohaaki geothermal system: a coincidental trapping of fluid being boiled toward dryness. Economic Geology, 92(4): 485-486.

Simmons, S.F., Gemmel, J.B. and Sawkins, F.J., 1988. The Santo Nino Silver-lead-zinc veins, Fresnillo district, Zacatecas, Mexico, part 2. Physical and chemical nature of ore-forming fluids. Economic Geology, 83(8): 1619-1642.

Sterner, S.M. and Bodnar, R.J., 1991. Synthetic fluid inclusion; X. Experimental determination of P-V-T-X properties in the CO2-H2O system to 6 kb and 700 °C. American Journal of Science, 291(1): 1-54.

Sverjensky, D.A., 1984. Oil field brine as ore-forming solutions. Economic Geology, 79(1): 23-37.

Takenouchi, S. and Kennedy, G., 1965. Dissociation pressures of the phase CO2.5 H2O. Geology, 73(2): 383-390.

Whitney, D.L. and Evans, B.W., 2010. Abbreviations for names of rock-forming minerals. American Mineralogist, 95(1): 185-187.

Wilkinson, J.J., 2001. Fluid inclusion in hydrothermal ore deposites. Lithos, 55(1): 229-272.

Yang, K. and Bodnar, R.J., 2004. Orthomagmatic origin for the Ilkwang Cu-W breccia-pipe deposit, southeastern Kyongsang Basin, South Korea. Journal of Asian Earth Sciences, 24(2): 259-270.

Zamanian, H., 1993. Mineralogy, paragenesis and genesis of lead and silver of Ahangaran, Malayer. M.Sc. Thesis, Tarbiat Moalem University, Tehran, Iran, 280 pp. (in Persian with English abstract)