Mineral chemistry of porphyry indicator minerals in Kuh-e-Kapout Cu porphyry deposit, Kerman Cenozoic Magmatic Arc: Petrogenetic and exploration implications

The Kuh-e-Kapout porphyry copper deposit is located at the south end of the Kerman Cenozoic Magmatic Arc in the Jebal-Barez area. This article presents a first-time study on the evolution and origin of the magmatic-hydrothermal system associated with porphyry mineralization in this deposit. This deposit is affected by Jebal-Barez-type granitoids, which exhibit weak mineralization properties in PCDs. Using tools such as porphyry indicator minerals can help recognize the process that led to mineralization in this deposit. Based on electron probe micro-analyzer data from Biotite, plagioclase, and amphibole as indicator minerals, the physicochemical conditions of the hydrothermal-magmatic system associated with mineralization have been determined. This deposit is hosted in an arc-related, shallow calc-alkaline intrusive complex with a quartz diorite composition. In the study of drill cores, the central parts exhibit potassic alteration linked to copper sulfide mineralization veins, which includes potassium-rich phases of hydrothermal biotite and potassium feldspar that replace primary ferromagnesian minerals. This alteration transitions into a superimposed phyllic zone, characterized by increased sericitization of feldspars and mostly the presence of quartz±pyrite±Chalcopyrite veins. In the upper parts of the drill cores, advanced argillic alteration is indicated by fine-grained sulfides, sericite, and fluorite. Quartz diorite in the phyllic alteration zone intruded by an unmineralized microdiorite dike. Research on indicator minerals in quartz diorite and microdiorite, particularly in the potassic mineralizing zone in quartz diorite intrusion, provided insights into the physicochemical conditions of ore formation condition: biotites on the Fe/(Fe + Mg)-Al^IV diagram are plotted in the phlogopite field, indicating the Mg-biotite type, which is associated with I-type granitoid. These data show the mantle-crust mixture source for quartz diorite with mineralized properties. Biotite and calcic amphibole geochemistry exhibiting calc-alkaline affinity with subduction-related orogeny for the quartz diorite and microdiorite porphyries. Based on biotite and amphibole geochemistry, the oxygen fugacity of the magmatism is estimated to have a range of high (HM) to moderate (NNO) characteristics, respectively. The ratio of log f(H₂O)/f(HF) > 1 and log f(H₂O)/ f(HCl) > 1 based on biotite geochemistry indicates the mineralized fluid was relatively water-rich. Data points of Plagioclase from quartz diorite and microdiorite plotted on the Na₂O + K₂O + CaO (wt%)-SiO₂ diagram, are between anorthite and albite. The excess Al in these data does not result from alteration and resulted from a magma with high PH₂O. Biotite chemistry indicates that mineralization in the quartz diorite magmatism occurred within a relatively closed system in the potassic alteration zone. Mineralization was observed as vines with a predominance of chalcopyrite and pyrite. The biotite chemistry from the analyzed samples is in good agreement with the results of biotite chemistry from other fertile deposits in UDMA, in terms of mineralization conditions and physicochemical inferred results. Generally, the silicate geochemistry in this study indicates physicochemical attributes of the Kuh-e-Kapout magmatic-hydrothermal system similar to those of other UDMA Cu porphyry deposits.