Exploration at the Kuscayiri Au (Cu) prospect and its implications for porphyry-related mineralization in western Turkey

The Kuscayiri An (Cu) deposit is localized along EW-trending linear silica-quartz structures or pods within altered Lower Miocene volcanics that are underlain by medium to high level Mesozoic granodiorite intrusions. The deposit is characterized by disseminated or fracture-controlled pyrite (up to 12%), variable amounts of silicification, hematite-pyrite matrix breccias produced by intense fracturing of siliceous rocks and moderate to weak saccharoidal to crystalline quartz stringer stockwork veining in small breccia pipes. An early quartz-sericite alteration event was focused along the EW-trending structures and resulted in the precipitation of pyrite. A later, more spatially extensive, advanced argillic alteration event overprinted the quartz-sericite event. The highest gold content is restricted to the high-temperature portion of the alteration zone characterized by stockwork or replacement quartz associated with sericite-pyrite-alunite-pyrophyllite. Trace gold and associated magnetite, arsenopyrite, realgar, specular hematite and chalcopyrite also occur within the smectite-illite/smectite-kaolinite-chlorite alteration facies. During the Tertiary, widespread subaerial to subaqueous arc volcanism developed in western Turkey, and numerous occurrences of high/low suflidation epithermal systems are associated with major NW-SE extensional deformation. The resultant NE-SW-trending grabens appear to be highly favorable host environments for the formation of porphyry-related gold-copper systems. The Kuscayiri mineralization may represent a lithocap with Au (Cu), the top of one such system yet to be discovered, (C) 2002 Elsevier Science B.V. All rights reserved.