Geology, petrography and geochemistry of volcanic rocks and granitoid intrusions in Churan gold and copper deposit (northeast Sirjan)

The Churan gold and copper deposit located 70 km northeast of Sirjan in the Dehaj-Sarduyeh structural subzone of the Urumieh -Dokhtar magmatic arc. Lithologically, the area mainly consists of the Middle Eocene volcanic rocks with dominant andesite to andesite-basalt crosscutting by the intrusive rocks and quartz dioritic to granodioritic dykes belonging to the Oligocene-Miocene time. The host granitoid rocks are classified as meta-aluminous I-type granitoid with high potassium calc-alkaline affinity dominated by plagioclase, biotite, hornblende, alkali feldspar, quartz and apatite, zircon, and opaque as accessory minerals. The rocks under study are characterized by large ion lithophile element (LILE) enrichment, high field strength element (HFSE) depletion, and high LREE/HREE ratios. On tectonomagmatic discrimination diagrams, the Churun granitoids are scattered on active continental margins to post-collisional fields. Mineralization occurred as gold and copper-bearing quartz vein and veinlets in the quartz diorite intrusive. Hydrothermal alterations associated with the mineralization contain silicification, sulfidation, tourmalinization, and sericitization. Ore mineral assemblages in the deposit consist of pyrite, arsenopyrite, chalcopyrite, bornite, sphalerite, galena, covellite, malachite, and iron hydroxides. The mineralization criteria as well as the spatial relationship between ore-bearing veins and alteration zones granite-granodiorite intrusion suggest that gold mineralization in the investigated area is related to granite-granodiorite emplacement and likely originated from those rocks.