Geochemistry, Alteration and Mineralization of Gold in Shanegh Area, Delijan,Isfahan

The Shanegh area is located in central part of Sanandag-Sirjan zone، 28km southeast of Delijan. Rock units exposing in the area consists of sedimentary (carbonate، sandstone، siltstone) volcano- sedimentary (andesite to andesitic tuff، tuff) and intrusive host rocks. The volcano- sedimentary units thought to be of Eocene to Quaternary ages which have been intruded by plutonic units. The main host rocks are monzonite، quartz monzonite، andesite and diorite. The host rocks have been altered by pervasive hydrothermal fluids. The alterations are sericitization، kaolinitization، carbonatization and silicification. The host rocks are characterized by fault or shear zones، vein systems، stockwork and dyke mineralization. Ore mineral assemblages are pyrite، chalcopyrite، Fe-oxide and Fe-hydroxides. We did not find gold minerals in our microscopic studies but the gold has been found in the lithogeochemical exploration. The results show that maximum grade of gold in some veins is about 2760 ppb and the mean grade of gold about 80 ppb. Comparing shanegh area main characteristics with epithermal gold deposits، shanegh area has the most similarities with epithermal gold mineralization; therefore، it is considered to be of this type.