Mineralogy, mineral chemistry and sulfur isotope geochemistry of the Baharieh copper deposit (NE Kashmar): implications for ore genesis

The Baharieh copper deposit with an approximately tonnage 1 million tons of copper ore, is located in the Khorasan Razavi Province and 30 km of northeastern of the Kashmar. Based on subdivision structural geology of the Iran, the deposit is situated in the Sabzevar zone and Taknar complex. The mineralization as stratabound nature in an ore-horizon with an approximately length of 200 m and E-W trending occurs in middle Eocene andesitic to rhyolitic-tuff. Chalcopyrite and pyrite are the main sulfide minerals which accompanies with accessory minerals such as bornite, galena, sphalerite, covelline, chalcocite, malachite and hematite. Based on evidence of the electron probe micro analysis (EPMA) detected the maximum gold and silver contents 0.21 and 0.1 ppm in chalcopyrite, respectively and the maximum silver content is 0.14 ppm in galena. According to mineral chemistry studies, pyrite of the Baharieh deposit obtained the average ratio Co/Ni=2.71, which can be indicate its hydrothermal source. According to the results of the geo-thermometry of the Sb/Bi ratio in the galena and geochemistry of sphalerite (high concentration of Cd with an average value of 9220 ppm and low Zn/Cd=67.54) physico-chemical and thermodynamic conditions of the ore-bearing fluid in the Baharieh deposit has been concordant with average-temperature hydrothermal-magmatic deposits. The variation ranges of δ34S isotopic in the chalcopyrite and pyrite samples are varies between -7.3 to 0.5 ‰.