Mineralogy and economic geology of Cheshmeh Hafez polymetal deposit, Semnan Province, Iran

The Cheshmeh Hafez polymetal deposit is located in Troud – Chahshirin mountain range in Southeastern Damghan. In this province, the volcanism and associated mineralization are closely related to major faults Anjilo and Troud with NW-SE trend. The exposed rocks in the study area consist of volcano clastic sequence of sandstone, tuff, volcano breccias and mostly andesitic and andesitic- basalt flows at Cheshmeh Hafez district. Alteration in Cheshmeh Hafez area is consisting of Proplilitization, Sericitization, Argillic alteration and Silicification. Mineralization occurred in three district stages; 1) quartz, carbonate with early pyrite and chalcopyrite assemblages; 2) the main stage of sulfide deposition, comprises early euhedral galena followed by galena and sphalerite, then galena, chalcopyrite, tetrahedrite, pyrite, bornite and digenite, and 3) quartz and calcite barren veins with minor pyrite and chalcopyrite. The average assays from 12 samples of Cheshmeh Hafez veins are; 0.15 g/t Au, 3.23 g/t Ag, 4.47 wt % Pb, 2.64 wt % Cu, and 1.73 wt % Zn. Fluid- inclusion homogenization temperatures (Th) in quartz fall within range of 140º-300º with salinities ranging from 4.7 to 18 wt. % NaCl equivalent. Comparison of Th versus final ice melting (Tmice) values indicates the occurrence of fluid mixing process. In order to evaluate extent of mineralization in depth, IP and RS techniques were used, which indicate the presence of mineralization in depth.