Ore mineralogy and fluid inclusions constraints on genesis of the Muteh gold deposit (western Iran)

Abstract

The Muteh gold deposit (NE of Golpaygan) in the central part of intrusive-metamorphic belt of Sanandaj-Sirjan zone comprises NW-SE trending gold-quartz vein occurred in metamorphic complex. Gold mineralization is associated with quartz veins that formed during regional deformation across the mylonitic zones in metamorphic rocks of predominantly meta-volcanic, gneiss and schist. The sulfidation (pyritization) and silicification hydrothermal alteration as the main alteration adjacent to ore body and the quartz-sulfide veins with sulfide content of variable from 10 to 60% is dominated by pyrite, chalcopyrite, emplectite, arsenopyrite and minor content of galena and sphalerite. Native gold in the quartz veins occurs as the inclusion in pyrite and chalcopyrite and fracture fillings within pyrite. Pyrite of the late assemblage (py2) shows a range of 0.03 to 0.31 wt.% Au and 0.00 to 0.26 wt.% As and chalcopyrite have content of Au (up to 0.30 wt.%), As (up to 0.12 wt.%), and Hg (up to 0.15 wt.%) were detected in chemical composition. Fluid inclusion (FI) shows that three types of FI include CO2-rich or carbonic FI have homogenization temperatures of CO2 (average 19.9°C), aqueous-carbonic FI (average salinities of 7.4 wt.%NaCl eq.