Alteration and mass balance of igneous rocks in the Taktelar area, northwest of Zahedan, SE Iran

The Taktelar area is located in 140 Km northwest of Zahedan city in the Sistan Suture Zone. In this area Eocene flysch-like rocks such as shale, siltstone and sandstone are intruded and extruded by Oligocene-Miocene plutonic, extrusive and sub-volcanic rocks. The igneous rocks are dacite, andesite, and diorite porphyry and are mainly altered. The mineralization in the Taktelar area occurs as dissemination and vein types in sub-volcanic and sedimentary rocks. The disseminated mineralization is characterized with wide formation of pyrite with or without Cu minerals and vein mineralization includes malachite, galena and Au-bearing silicic veins. The hydrothermal alterations are potassic, phyllic, tourmalinitic, argillic, silicic and propylitic. The result of mass change calculation shows enrichments of SiO2 and depletion of other elements in phyllic alteration zone. In argillic alteration zone, contents of As, Mo, Zn, and Pb were enriched and other elements were depleted or were not changed. The alteration zones with quartz stockwork veins and enrichment of SiO2 and K2O have the most enrichment of Cu and Mo. The behavior of the elements in the propylitic alteration zone is different and generally increasing of the main elements is more significant. The ore-making elements have more enrichment in samples with silica veins so that the highest enrichment of copper and molybdenum occurs in rocks with higher SiO2 and K2O and quartz veins. Generally, in most altered zones, contents of copper, molybdenum, lead, zinc and arsenic show enrichment and rare earth elements show depletion. Light rare earth elements show more depletion than heavy rare earth elements, indicating their more mobility in hydrothermal systems.