Mineralogy, geochemistry, fluid inclusion, and stable sulfur isotope investigation of the Terziali shear-related orogenic gold deposit (Central Anatolia, Turkey): implications for ore genesis and mineral exploration

Abstract

The Terziali gold mineralization is located within the Central Anatolian Crystalline Complex and represents one of the significant gold occurrences in central Turkey. This gold mineralization is emplaced along the Demirli Thrust Zone striking northwest-southeast with a southwest dip. The hanging wall of this thrust zone consists of Carboniferous metasedimentary rocks, whereas the footwall rocks is dominated by a Permian-aged marble. The metamorphic rocks are intruded by the upper Cretaceous-Paleocene cayagzi syenite, and the mineralization is mainly hosted by breccia cements and clasts, and fine-grained grayish fracture fill quartz veins. This study reports new geochemical, mineralogical, fluid inclusion, and S stable isotope data from the Terziali gold mineralization in order to better understand its ore genesis. The mineralization is constituted of dravite, quartz, sericite/fuchsite, and carbonate in the proximal alteration zone, whereas the distal alteration zone in the Terziali is characterized by silicification along the thrust contact. The ore mineralogy is mainly composed of disseminated pyrite, Fe-oxides, and lesser amounts of chalcopyrite and arsenopyrite, and minor to trace gold. In relation to the first and second mineralization stages, the Terziali mineralization presents compatible homogenization temperatures (Th degrees C) range between 336-248 degrees C and 245-178 degrees C, and the mineralized fluids were observed over two phases of relatively low salinity and high salinity average: 2.2 and 21.8 wt% NaCl equ. with an average of 10.3 wt% NaCl equivalent, respectively. Further, the sulfur isotope delta S-34 compositions from the Terziali mineralization range from 5.6 to - 12.1 parts per thousand (mean value of - 8.8 parts per thousand) and indicate the involvement of magmatic and sedimentary sourced solutions. The overall geochemical, mineralogical, and stable isotope data reported here indicate that the Terziali gold mineralization exhibits similar characteristics with shear-related orogenic gold deposits, and this finding can be also indicative for the presence of similar systems in Central Anatolia and the western Tethyan Belt.