Mineralogy, structure texture and geochemistry‌ of Fadiheh Cu-Au mineral occurrence, northwestern Torbat Heydariyeh

Fadiheh copper-gold prospect area in northwest of Torbat-e Heydariyeh in Khorasan Razavi Province is located in the central part of the Khaf-Kashmar-Bardaskan magmatic belt. This area includes outcrops of Eocene volcanic-pyroclastic units with felsicـintermediate nature. The lavas are andesite and latite, and pyroclastic units include rhyodacitic tuff, andesitic lithic tuff and ignimbrite. Intrusive rocks consist of hornblende monzogranite, synogranite, pyroxene diorite porphyry and quartz monzonite porphyry. Mineralization has structural control and formed as vein-veinlets in accordance with the main trend of NW-SE and NE-SW faults in the region. Mineralization veins have generally N45 ° -75 ° E and N15 ° -30 ° W trending, 2 to 25 m length and 0.2 to 2 m width. The most important veins in the area include quartz + specularite ± pyrite and quartz + specularite ± chalcopyrite. The host rocks are pyroxene diorite porphyry, quartz monzonite porphyry and hornblende monzogranit. The structure and texture of mineralization includes vein-veinlet, open space filling, breccia, secondary replacement, colloform and disseminated. The alteration associated with veins are silicification and chloritization. The propylitic, silicification, chloritization and argillic alteration zones are observed within host rocks and other units in the area. Primary mineralization are specularite, chalcopyrite, pyrite and galena and secondary minerals are malachite, chalcocite, covellite, goethite, hematite, limonite, azurite and chrysocolla. Maximum of geochemical anomalies in veins are up to 5% Cu, up to 3% Pb, 50 g/t Ag, 100 g /t As and up to 791 ppb Au. The geological setting, lithology, mineralogy of mineralized veins, structure and texture, extent and type of alteration zones show that the mineralization in Fadiheh prospect area is iron-oxide copper-gold (IOCG) type.