Situated about 130 km northeast of Tabriz (northwest Iran), the Mazra’eh Shadi deposit is in the Arasbaran metallogenic belt (AAB). Intrusion of subvolcanic rocks, such as quartz monzodiorite-diorite porphyry, into Eocene volcanic and volcano-sedimentary units led to mineralisation and alteration. Mineralisation can be subdivided into a porphyry system and Au-bearing quartz veins within andesite and trachyandesite which is controlled by fault distribution. Rock samples from quartz veins show maximum values of Au (17100 ppb), Pb (21100 ppm), Ag (9.43ppm), Cu (611ppm) and Zn (333 ppm). Au is strongly correlated with Ag, Zn and Pb. In the Au-bearing quartz veins, factor group 1 indicates a strong correlation between Au, Pb, Ag, Zn and W. Factor group 2 indicates a correlation between Cu, Te, Sb and Zn, while factor group 3 comprises Mo and As. Based on Spearman correlation coefficients, Sb and Te can be very good indicator minerals for Au, Ag and Pb epithermal mineralisation in the study area. The zoning pattern shows clearly that base metals, such as Cu, Pb, Zn and Mo, occur at the deepest levels, whereas Au and Ag are found at higher elevations than base metals in boreholes in northern Mazra’eh Shadi. This observation contrasts with the typical zoning pattern caused by boiling in epithermal veins. At Mazra’eh Shadi, quartz veins containing co-existing liquid-rich and vapour-rich inclusions, as strong evidence of boiling during hydrothermal evolution, have relatively high Au grades (up to 813 ppb). In the quartz veins, Au is strongly correlated with Ag, and these elements are in the same group with Fe and S. Mineralisation of Au and Ag is a result of pyrite precipitation, boiling of hydrothermal fluids and a pH decrease.
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Barnes H.L. 1979. Solubilities of ore minerals. [In:] H.L Barnes (Ed). Geochemistry of hydrothermal ore deposits 2nd ed. John Wiley & Sons New York. pp 404-410.
Bodnar R.J. 1993. Revised equation and table for determining the freezing point depression of H2O-NaCl solutions. Geochimca et Cosmochimica Acta 57 683-684.
Browne P.R.L. 1978. Hydrothermal alteration in active geothermal fields. Annual Reviews of Earth and Planetary Science 6 229-250.
Browne P.R.L. & Ellis. A.J. 1970. The Ohaki-Broadlands hydrothermal area New Zealand: Mineralogy and related geochemistry. American Journal of Science 269 97-131.
Buchanan L.J. 1981. Precious Metal Deposits Associated with Volcanic Environments in the Southwest: In Relations of Tectonics to Ore Deposits in the Southern Cordillera. Geological Society of Arizona Digest 14 237-262.
Cole D.R. & Drummond S.E. 1986. The effect of transport and boiling on Ag/Au ratios in hydrothermal solutions: a preliminary assessment and possible implications for the formation of epithermal precious metal ore deposits. Journal of Geochemical Exploration 25 45-79.
Davis C. 1986. Statistics and Data Analysis in Geology. John Wiley & Sons New York. 640 pp.
Dreier J.E. 2005. The Environment of vein Formation and Ore Deposition in the Purisima-Colon Vein System Pachuca Real del Monte District Hidalgo Mexico. Economic Geology 100 1325 - 1347.
Grancea L. Bailey L. Leroy J. Banks D. Marcoux E. Milési J.P. Cuney M. André A.S. Istvan D. & Fabre C. 2002. Fluid evolution in the Baia Mare epithermal gold/polymetallic district Inner Carpathians Romani. Mineral Deposita 37 630-647.
Hedenquist J.W. Arribas A.R. & Gonzalez-Urien E. 2000. Exploration for epithermal gold deposits. Reviews in Economic Geology 13 245-277.
Henley R.W. Brown K.L. 1985. A practical guide to the thermodynamics of geothermal fluids and hydrothermal ore deposits. Reviews in Economic Geology 2 25-44.
Howarth R.I. 1993. Statistics and Data Analysis in Geochimical Prospecting. [In:] G.J.S Govett (Ed). Handbook of Exploration Geochemistry. Elsever Amsterdam. 2 44-75.
Krauskopf K.B. 1979. Introduction to geochemistry. 2nd ed. McGraw-Hill Kogakushu New York. 617pp.
McLemore V.T. 2008. Geochemistry and statistical analyses of epithermal veins at the Carlisle and Center mines Steeple Rock District. New Mexico USA. Arizona Geological Society Digest 22 485-496.
Nabavi M. 1976. An Introduction to the Geology of Iran. Geological Society of Iran Teheran. (in Persian). 109 pp.
Nie N.H. Hull C.H. & Jenkins J.G. Steinbrenner K. & Bent P.H. 1975. Statistical package for the Social Sciences. McGraw-Hill Book Co New York 675 pp.
Pokrovski G.S. Borisova Yu.A. & Harrichoury J.C. 2008. The effect of sulfur on vapor- liquid fractionation of metals in hydrothermal systems. Earth and Planetary Science Letters 266 345-362.
Radmard K. Zamanian H. Hosseinzadeh M.R. & Ahmadi Khalaj A. 2017. Geochemistry and hydrothermal evolution of the Mazraeh Shadi-Hizehjan precious and base metal deposit northeastern Tabriz Iran. Journal of Mineralogy and Geochemistry 194-3 227-250.
Rassi R. & Afzal P. 2015. Correlation between Au Lithogeochemical Anomalies and Fault-density using Geostatistical and Fractal Modeling in Sharaf Abad-Hizehjan Area NW Iran. Universal Journal of Geoscience 3 51-58.
Sillitoe R.H. 1999. Styles of high-sulfidation gold silver and copper mineralization in porphyry and epithermal environments. [In:] Weber G. (Ed.): Pacrim ’99 Congress Bali Indonesia. Proceedings. Australasian Institute of Mining and Metallurgy Parkville 29-44.
Sillitoe R.H. & Hedenquist J.W. 2003. Linkage between volcanotectonic settings ore-fluid compositions and epithermal precious- metal deposits. Society of Economic Geologist Special Publication 10 315-343.
Simmons S.F. & Browne P.R.L. 2000. Hydrothermal minerals and precious metals in the Broadlands-Ohaaki geothermal system: Implications for understanding low-sulfidation epithermal environments. Economic Geology 95 971-999.
Tuysuz N. & Yaylali G. 2005. Geostatistics. Karadenis Technical University Publication 220 400 pp.