Investigation of the mineralogical, petrographical and geochemical properties of the Göksel (Hayrat-Trabzon) Cu-Fe skarn mineralization

Göksel Cu-Fe skarn mineralization is located in the Göksel district from the Hayrat county of the Trabzon city. Hamurkesen (Liassic), Berdiga (Upper Jurassic-Lower Cretaceous), Çatak (Late Cretaceous) formations and Kaçkar Granitoid (Late Cretaceous-Eocene (?)) find from basement to upper. The Kaçkar Granitoid cuts all these units and skarn mineralization has occurred at the limestone contacts of the Berdiga. The youngest unit in the studied area is Cretaceous-Eocene (?) dykes. While pyroxene, garnet, epidote and magnetite were less abundant in the endoskarn zone, these minerals were more abundant in the exoskarn zone. Mineral paragenesis of the skarn mineralization form magnetite, pyrite, pyrrhotite, sphalerite, chalcopyrite, galenite, hematite, arsenopyrite, manganese, molybdenite, sphene, rutile, ilmenite, mechanite (vallerite,), wolframite, silver and tellurite. Granitoids associated with the skarn mineralization are found to be in calc-alkaline and metaluminium character and are generally similar to volcanic arc granitoids it is thought to be post-collisional granitoids. The garnets in the study area were in the composition of andradite and grossular andradite, and the pyroxenes were hedenbergite, diopside and hedenbergitic diopside. The compositions of these minerals matched the Cu and Fe deposits classes. According to the fluid inclusion studies in the primary origin and two-phases (liquid+gas) inclusions of garnet and epidote from the exoskarn zone, the homogenization temperature and salinity of the garnet are from 340 to 434 oC and 7.9 to 11.5 % NaCl (equivalent salinity), respectively and homogenization temperature of the epidote is from 287 to 312 oC. Skarn-forming fluids are thought to originate from NaCl-CaCl2 composition fluids.