Bahman Mokhtarzadeh Mohammadi; Hashem Bagheri
Volume 2, Issue 5 , June 2011, , Pages 1-18
Abstract
The Meskani ore deposit is located in the Central Iran and Anarak-Khur metamorphic area. Microscopic studies were conducted on polished, thin polished and double polished thin sections ...
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The Meskani ore deposit is located in the Central Iran and Anarak-Khur metamorphic area. Microscopic studies were conducted on polished, thin polished and double polished thin sections of quartz and calcite minerals from ore bearing veins. Chalcocite, Nickeline, Chalcopyrite, Rammelsbergite and Malachite were recognized which Nickeline is surrounded by Rammelsbergite representing deposition of nickel and increasing of arsenide in ore bearing solutions. Most of the studied fluid inclusions are from liquid rich two phases (L + V) type. Genetically, primary types were selected for this study. Based on freezing studies, calculated temperature of last melting point (Tlm) is from -1.6 to -18.5 °C that is equal to 2-22.5 % wt eq. NaCl. Heating studies, have revealed a homogenization temperature (TH) range of 130-160 °C. Homogenization temperature - salinity binary plots show two distinct fluids that can represent two different phases of mineralization or two distinct different sources of ore bearing fluids. Probably one of them represents volcanogenic ore bearing fluid and the other represents basinal brine ore bearing solution. The geochemical analysis of collected samples from different parts of Meskani ore deposit, elements including Co, Ni, Cu, Zn, Pb, Th, U, Zr and Sr were determined among of them Co, Cu, Ni and U are the most important. Scatter diagrams of these elements were plotted and their correlations determined. Results of these analyses revealed that the average of U, Th, Ni, Cu are 269, 26, 452, 10786 ppm, respectively. Another interesting feature is the inverse correlation between U content and Th/U ratio. This feature represents that high U content in these rocks is not related to magmatic differentiation. In contrast of vein samples, there is not any correlation between U, Cu and Ni changes in country rock samples. This is one of the specific characteristics of shoshonites and andesites that represent these elements have not been originated from country rocks. The geochemical and petrographical studies have shown that country rocks are mainly shoshonitic in composition.
