Verifying Muteh Gold Deposit as an Intrusion Related Gold System (IRGS)

The Muteh gold deposit located in the center of Sanandaj-Sirjan Zone (SSZ) in western Iran. Gold mineralization is related to series of quartz and quartz-sulfide veins, lenses and veinlets, cutting the Neoprotrozoic crystalline basement rocks, along a NW-SE trending shear zone. Gold mineralization is closely associated with hydrothermal alteration along the ductile shear zones, with a typical greenschist facies assemblage of quartz+sericite+chlorite+albite, plus sulfidation and silicification alteration zones adjacent to ore body. Ore minerals include; pyrite, chalcopyrite, emplectite (Cu-Bi sulfide), arsenopyrite, pyrrhotite, bismuth, gold and subordinate galena and sphalerite. Native gold occurs in the quartz veins and adjacent to wall rocks as inclusions in the second generation of pyrite and chalcopyrite in form of fracture fillings within rim or around euhedral to subhedral coarse pyrite. Fluid inclusions in quartz veins contain carbonic, aqueous-carbonic and aqueous types in the Chah-Khatoon and Senjedeh gold mines. Homogenization temperature of CO2 (ThCO2) in carbonic inclusion is between 12.6 to 27.3 ̊C. Aqueous-carbonic fluid inclusions show salinities of 2.3 to 12.5 NaCl eq. wt% and total homogenization of 145.6 to 304.2 ̊C. The aqueous fluid inclusions, based on association with auriferous and barren veins categorized as; 1) salinity of 2.1 to 15.2 NaCl eq. wt% and total homogenization of 212.2 to 297.6◦C in auriferous quartz-sulfide veins, and 2) salinity of 16.2 to 28.2 NaCl eq. wt% and total homogenization of 147.4.2 to 245.6◦C in barren quartz veins. While most of aforementioned characteristics of the Muteh deposit are consistent with orogenic (mesothermal) gold deposit, but features such as genetic linkage with tectonic evolution of lithospheric mantle through upper crust with the tectono-magmatic history of SSZ accompanied with extensional structure setting, ore geology style, alteration assemblages, mineral chemistry, vertical elemental zonation and fluid inclusions characteristics presented in this research, it may inferred that gold mineralization in the Muteh deposit can be favored as an reduced intrusion related gold system (IRGS).