Iron oxide-copper +/- gold deposits in Turkish Tethyan collage

Abstract

Iron oxide-copper-gold (IOCG) deposits define a group of diverse, epigenetic Cu-Au deposits to which several economically important deposits belong, and these are very limited in Tethyan-Eurasian metallogenic belt. As a part of this belt, Turkey is a host to several IOCG deposits formed in post-collisional settings related to subduction of NeoTethyan ocean beneath the Eurasian plate. The present work evaluates the IOCG potential of Turkey by studying three iron oxide-rich deposits from two different regions: (1) central Anatolian post-collisional setting and (2) western Anatolian extensional province. The study covers alteration, mineralogy, geochemistry, fluid inclusion characteristics, and geochronology of these deposits. The geological features of the deposits in Hasancelebi, Divrigi and Samli regions are comparable to the IOCG deposits elsewhere. The investigations in Turkey revealed that some of the iron-oxide mineralizations occur in metasomatized magmatic rocks that underwent a pervasive alkaline metasomatism. Early-distal alteration is typically characterized by extensive sodic +/- calcic mineral assemblages, chiefly scapolite +/- albite-garnet-diopside- actinolite. The potassic alteration products are K-feldspar and phlogopite/biotite or sericite, and the calcic alteration assemblages are dominated by diopside-hedenbergite, and garnet. The magnetite mineralization is commonly associated with potassic zones, while the copper-gold mineralization is associated with late stage sericitic alterations and carbonated rocks mainly along structural discontinuities. The host rocks and alterations are confined to crustal scale regional strike-slip and normal faults. The deposits were formed in post-collisional, late orogenic extensional settings related to subduction of Southern NeoTethyan ocean beneath Eurasian plate during late Cretaceous to Miocene period.