Genesis and source of ore-forming hydrothermal fluids in Efemçukuru (Menderes-İzmir) epithermal gold deposit

The Efemçukuru Gold Mine, located in the Western Tethys Metallogenic Belt, is in the Western Anatolia Extension Zone. The Mine, which is located in Seferihisar Uplift that consists of Late Cretaceous Bornova Flysch Zone bounded two side by Seferihisar and Orhanlı strike-slip fault zones, comprise mainly of Kestanebeleni and Kokarpınar multi-phase intermediate sulfidation epithermal vein systems. Kestanebeleni which is being operated, Kokarpinar which is in advanced exploration stage and the other epithermal veins which are in exploration stage are hosted by schist, phyllite and hornfels of the Bornova Flysch. Mineralization was formed in listric structures strikes WNW, dip mostly 30-450 toward the NNE, and strikes NNW and dip mostly 45-650 towards the ENE. NNW-oriented relay ramps related to WNW-oriented structures were filled by ore-bearing hydrothermal fluids and formed rich ore bodies. Protholith of the hornfels in the center of the Mineralization is the pelitic-psammatic rocks of the Bornova Flysch. The hornfels formation and the following hydrothermal activity is considered a result of buried intrusive. Three sets of rhyolite dikes with NNW dipping (25-55) and WNW-striking, which is coeval with Miocene Cumaovası Volcanics, shows important influences on the structural control of the mineralization. Non-economic disseminated and vein type mineralization are comprised of pyrite-pyrrhotite-galena-sphalerite-chalcopyrite-magnetite-hematite, which is related to calc-silicate (quartz-chlorite-epidote-amphibole-feldspar) alteration in and around hornfels and cut by epithermal veins of the late hydrothermal phase. Rhodonite, rhodochrosite, quartz, calcite and sulfide (pyrite, galena, sphalerite and chalcopyrite) minerals are the main gangue minerals of the vein type mineralization. In addition, clay mineral predominated alteration assemblages, are in association with the late phase hydrothermal fluid. Gold is observed in the sulfide minerals and / or in free form. Fluid inclusion studies from quartz yields homogenization temperatures in a range between 99 and 309°C with salinities between 0.8 and 4.8 wt.% NaCl equivalent which is similar to those of Kestanebeleni vein.