Exploratory geochemistry studies of heavy minerals, stream sediments and rock in Asbkhan region, Heris, northwest Iran

The study area is located in the south of Qushadagh mountain range, in the north of Asbkhan village, Heris township. In terms of structural geology of Iran, this area is located in the main zone of Central Iran and Alborz-Azerbaijan sub-zone. The geological units of the region are including Eocene igneous and pyroclastic rocks with combination of andesitic, trachyandesitic, basaltic, tuffic and ignembritic. The semi-deep intrusive mass with Oligocene age, with the combination of quartz diorite, diorite and quartz monzonite in the form of stock and dyke is exposed in the area. Under the influence of hydrothermal processes originating from this intrusive mass and infiltration of fluids through the sedimentary-volcanic units of the Middle Eocene, extensive alterations (sericitic, medium argillic, propylitic and siliceous) have been taken place in the region. Preliminary results of geochemical studies of stream in the region led to the identification of several areas with grade 1, 2 and 3 anomalies of heavy minerals. The most important heavy minerals identified, include hematite, goethite, magnetite, pyrite-oxide, pyrite and zircon, These minerals and have closely relation to the alteration zones and veins mineralization. The conformity of the geochemical halos map with the geostructure and alteration map of the region shows a very high correlation between these regions and possibly the important role of faults and joints in the occurrence of alteration zones and abnormal regions. Anomaly maps and geostatistical analyzes performed on the findings in stream sediments and heavy minerals show that the enrichment of Ag, Au, Mo, Cu, As, Pb, Sb and Zn elements is higher than the background and the Au, Ag, Cu, As and Pb elements can be used as trace elements for epithermal gold reserves.