معدن فیروزه نیشابور: نخستین کانی سازی مس- طلا- اورانیم- عناصر نادر خاکی سبک نوع IOCG در ایران

Abstract

Neyshabour turquoise mine is located in northwest of Neyshabour, southern Quchan volcanic belt. Eocene andesite and dacite forming as lava and pyroclastic rocks cover most of the area. Subvolcanic diorite to syenite porphyry (granitoids of magnetite series) intruded the volcanic rocks. Both volcanic and subvolcanic rocks are highly altered. Four types of alteration are recognized including: silicification, argillic, calcification and propylitic. Silicification is dominant followed by argillic alteration. Mineralization is present as stockwork, disseminated and hydrothermal breccia. Hypogene minerals are pyrite, magnetite, specularite, chalcopyrite, and bornite. Secondary minerals are turquoise, chalcocite, covellite, and iron oxides. A broad zone of gossan has developed in the area. Oxidized zone has a thickness of about 80 m. Mineralized samples show high anomalies of Cu, Au, Zn, As, Mo, Co, U, LREE, Nb, and Th. Both aeromagnetic and radiometric (U and Th) maps show very strong anomalies (10 × 5km) within the mineralized area. Based on geology, alteration, mineralization, geochemistry, and geophysics, Neyshabour turquoise mine is a large Iron oxide Cu-Au-U-LREE (IOCG) mineralized system. In comparison with other IOCG deposits, it has some similarities with Olympic Dam (Australia) and Candelaria (Chile). In comparison with Qaleh Zari and Kuh Zar mines, Neyshabour turquoise mine is the first Iron oxide Cu-Au-U-LREE (IOCG) mineralized system discovered in Iran.