Geology, Mineralization, and Geochemistry of the Nik Pey Mineral Occurrence, West of Torbat-e-Jam, Khorasan Razavi Province: Evidence for Iron Oxide-Copper-Gold (IOCG)

The Nik Pey prospect area is located in northeastern Iran, within Khorasan Razavi province, along the Khaf-Kashmar Magmatic Belt (KKMB). This belt has a high potential for the formation of iron oxide-copper-gold (IOCG) deposits and magnetite-related mineralization. The lithology of the area includes sedimentary units such as conglomerate, sandstone, siltstone, and limestone; pyroclastic units such as andesitic lithic tuff and andesitic tuff, volcanic units like andesite and dacite, as well as metamorphic units such as phyllite. Several subvolcanic intrusive bodies with dioritic, quartz dioritic, quartz monzodioritic, monzodioritic, and monzonitic compositions have intruded these units. These subvolcanic units are predominantly porphyritic in texture and contain primary minerals such as plagioclase, alkali feldspar, hornblende, and biotite. Field and petrographic observations reveal widespread hydrothermal alterations, including chloritization, propylitic, sericitic, carbonate, and silicification types, which are further subdivided based on intensity and mineral assemblages. Mineralization mainly occurs in association with moderate to intense chloritization-silicification, propylitic, and propylitic-silicification alteration zones. Mineralization is predominantly hosted within hornblende diorite porphyry and hornblende monzodiorite porphyry intrusions, and is structurally controlled, primarily localized along vein and veinlet systems. The primary ore minerals include specularite, magnetite, chalcopyrite, and pyrite, along with secondary minerals such as goethite, hematite, chalcocite, and malachite. Vein-veinlet types are classified into four main groups: specularite-rich, specularite ± quartz, specularite + magnetite ± chalcopyrite, and chalcopyrite ± pyrite ± specularite. Geochemical analyses show high concentrations of copper (492-48152 ppm), iron (4-19 wt%), and gold (up to 1854 ppb). These results, along with geological and mineralogical evidence, suggest a high potential for IOCG-type mineralization in the Nik Pey prospect area.