Study on mineralization at Jian copper deposit, Fars province, using petrographical and geochemical data

Jian Cu deposit is hosted by Surian volcano-sedimentary complex of Permo-Triassic age on the eastern edge of the Sanandaj-Sirjan metamorphic zone at a distance of 195 km from Shiraz، southwestern Iran. The complex consists mainly of metabasalt، chlorite-quartz schist، chlorite-muscovite schist، mica schist and graphite schist. Pyrite is the most important sulfide and chalcopyrite is the major Cu-bearing mineral occurring as disseminated grains and veinlets in host chlorite-quartz schist and chlorite-muscovite schist. Chondrite-normalized REE pattern of metabasalt with La/LuN=2/9 indicates mantle tholeiitic basalt as the source of metamorphosed igneous rocks. Geochemical data on the metabasalts، especially the content of immobile elements (e. g.، Ti) and High Field Strength Elements (HFSE) (e. g.، Zr، Nb and Y)، show low degree of partial melting for parental magma with E-MORB affinity. Chloritic، silicification and minor sericitic assemblages are the main alteration types associated with the Jian Cu deposit. The Y/Ho ratio of Cu ores varies from 29. 9 to 32. 5، indicating the important role of sea water in the mineralizing system. Petrographical and geochemical data indicate that the Jian Cu deposit was formed as volcano-sedimentary hosted massive sulfide. The Ishikawa alteration index (AI) in association with chlorite-carbonate-pyrite index (CCP) is useful for the geochemical exploration of Cu deposits in the study area.