Evaluation of geological and geochemical exploration data of Alishar copper index and determination of its mineralization type

Alishar index with high potential to Cu-Au mineralization is located in Urumieh-Dokhtar magmatic belt and in Arak province. Geological units of the area consists mainly of andesitic, Trachyandesitic-basaltic andesite lava, andesite to basaltic andesite tuff and rhyolitic to dacitic tuff which is affected by hydrothermal solutions so the igneous rock units display some kinds of alterations such as phyllic, propylitic, argilic and silicic alterations as well as iron oxide (hematite, goethite) and copper mineralization. Plentiful silicified and mineralized veins and veinlets is a favorable environment for gold mineralization. High correlation between Cu and Fe can be explained by the presence of chalcopyrite and correlation between Au, As and Bi are attributed to substitutions in Cu, Bi minerals and arsenopyrite. Multivariate statistical analyses have demonstrated three stages in mineralization in the area. The first stage shows: Cu, Au, Ag, Bi, Mn, Co and Zn; the second stage includes: Fe, Sb and the last stage comprises as, Cd and Mo enrichment. The evidences comprising host rock composition, ore minerals, alteration types, tectonic regime, geochemical analysis results and high correlation between Fe, Cu and Au and also elevation in concentration of these elements demonstrates that Alishar mineralization is similar to IOCG.