Geology, mineralogy, geochemistry and genesis of the Kuh-Mil copper (gold) deposit, Northeast Saveh, Markazi province
Subject Areas :Mohammad Kazem Ghiasi zadeh 1 , Masoud Alipour-Asll 2 , S.M. Meshkani 3
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Keywords: Intermediate-sulfidation epithermal, Cu (Au) deposit, Kuh-Mil, Saveh,
Abstract :
The Kuh-Mil copper (gold) deposit is located 25 km northeast Saveh and in the middle part of Urmia-Dokhtar magmatic arc. Volcanic and pyroclastic rocks such as andesite, trachyandesite, andesite basalt with Middle- Late Eocene age are outcropped in this area. The Late Eocene hypabyssal quartz monzodiorite to monzodiorite intrusive rocks have been injected into the volcanic rocks. The calc-alkaline igneous rocks are classified as I-type granitoids, and are related to the magmatic arcs in the active continental margin and collisional zones. Mineralization is mainly observed as vein- veinlets, breccia and rarely disseminated forms in intrusive and volcanic rocks. Primary ore minerals include chalcopyrite (main ore mineral), pyrite, specularite and hematite, and secondary types include chalcocite, covellite, malachite, goethite and limonite. Alteration zones are propylitic, argillic, phyllic (quartz, sericite ± pyrite), silicic, iron oxide, tourmalinization and carbonate alteration. In the altered rocks, SiO2, K2O, Rb, Zr, Nb, Ta, U, Th, and light rare earth elements (LREEs) are enriched, while the rest of the major oxides, Ba, Sr, Cs, and heavy REEs show depletion. In the Kuh-Mil mineralization system, Cu has a good positive geochemical correlation with Au, Ag, Bi, Cd, and As. The homogenization temperature and salinity of fluid inclusion in quartz vary from 115 ºC to 200 ºC (average 164 ºC) and from 2.68 to 24.67 (average 20.25) wt.% NaCl equivalent, respectively. Based on the homogenization temperature and salinity, the trapping pressure of fluid inclusions is estimated to be less than 10 bars, and depth of placement is less than 500 meters. The Kuh-Mil Cu (Au) mineralization system is classified in the category of intermediate- sulfidation epithermal deposits.