Geology and mineralization of the NE Narbaghi epithermal Cu (Au-Ag) deposit (Saveh)

The mineralization of Cu (Au-Ag) NE Narbaghi is located in the middle part of the Urumieh-Dokhtar magmatic arc, adjacent to the Kuh-Pang and Narbaghi Cu deposits. The main rock units include Eocene volcano-sedimentary rocks and subvolcanic Oligo-miocene that their location is related to strike-slip faults in shallow sedimentary basins. Hydrothermal alteration includes silicification, argillic (intermediate-rarely advanced), propylitic, sericitic, carbonatization and sulfidization. Mineralization is directly related to fractures and relatively long veins (<400 with average width of 1m) with breccia, disseminate and vein-veinlet textures. These veins often include quartz, sericite, siderite and chalcopyrite, bornite, chalcocite, pyrite, covelite and rarely sulfosalts such as tennantite and tetrahedrite. This system starts with different types of alteration in the form of white–quartz veins and continues with hydrothermal breccia and infiltration of siliceous-sulfide fluids. Copper has the highest correlations with zinc, silver, arsenic and gold. Mineralization forms at 240-145° C and salinity of 20 to 30 wt.% NaCl. The coexistence of liquid-rich two-phase fluids and single-phase vapor refers to the boiling process and the reduction of temperature and pressure drop. Accordingly, this system provides evidence of intermediate sulfidation epithelial systems in the magmatic arc. The magmatic fluid in the presence of permeable structures and mixing with peripheral fluids is probable cause copper-gold precipitation together with siderite.