Geological & Structural properties of the Öksüt High Sulfidation Epithermal Gold Deposit South-Central Anatolia (Turkey)

The Öksüt high-sulfidation gold deposit is located in south-central Turkiye along the Asia minor segment of the Tethyan mineral-belt. The deposit is situated in the Miocene age Develidag volcanic complex on the eastern margin of the Sultansazligi pull-apart basin. The Sultansazligi basin formed by transtensional Miocene deformation along the northeast trending Ecemis fault zone, which is part of the tectonic release structural system that developed in south central Anatolia in response of the collision of the Arabian plate with the accreted blocks of Anatolia. In the area of the Öksüt deposit, the Develidag volcanics consist mostly of medium-K andesitic to basaltic lava flows and related flow breccias with a calc-alkaline affinity.  The stratigraphy generally dips moderately in a westward direction. Multiple centers of high sulfidation mineralization are present across the property, however the main control on zones hosting economics grades of gold mineralization is an approximately three-kilometer north-northwest trending structural zone. This trend forms an acute angle to the structural margin of the adjacent Sultansazligi basin which trends NNE.There are four distinct centers of mineralization along the zone which are oriented roughly perpendicular to the main NNW structure trend. Economic resources that are currently being mined are hosted in the two central zones (Keltepe&Güneytepe). Mineralization in the system consists of three broader zones, a deeper hypogene zone consisting of pyrite and enargite, a supergene enrichment containing a mixture of pyrite and chalcocite, and a near surface oxide zone with local isolated areas of mixed oxide and sulfide material.  Drilling has traced pervasive oxidation to depth of over 300 meters below surface.  Currently economic mineralization is limited to the oxide zone which is mined by open pit methods and processed by heapleaching.  Intramineral breccias are the dominant host for mineralization with lessor amounts of mineralization trending subparallel to bedding and indicating an element of local stratigraphic control. Drilling has traced intramineral breccias over a vertical interval exceeding 600 meters.  Alteration also exhibits a very distinct zonation. At depth drilling has cut phlogopite +/- chlorite, overprinted by white mica and crosscut by locally abundant anhydrite. This grades upward through a white mica dominated zone into the nearer surface oxide zone.  Intervals of silicified intramineral breccia in a pyrophyllite-alunite +/- white mica or kaolinite altered matrix are interpreted to be structurally feeder zones to the near surface high-sulfidation mineralization. In the near surface oxide environment economic gold mineralization occurs in a complex overlapping domains of mixed argillic to advanced argillic mineral assemblages where kaolinite, montmorillonite, or alunite +/- silica and pyrophyllite can locally be the dominate alteration mineral. Alunite occurs in both crystalline hypogene and more aphanitic supergene forms with jarosite. Pyrophyllite, alunite +/- topaz or jarosite occur with a mottled or patchy silica also form distinct alteration zones at multiple levels in the both the oxide and sulfide zones. Zones of more pervasive silicification are commonly associated with white mica or kaolinite in the oxide zone.  Near surface iron oxides consist mostly of hematite and goethite.