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

Abstract

The Kuscayiri Au (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 sulfidation 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.