Geologic, mineralogic, geochemical and genetic studies of Arzular (Gümüşhane) Gold Deposit Northeast-Turkey

Arzular mineralization (Gümüşhane, NE Turkey) has emplaced as fault-controlled into NE-SW trending and NW dipping, and also about EW trending and North dipping fractures within the Eocene aged Alibaba Formation. The main mineralizations have developed along a N70E trending fracture zone in Kuzdağı Sırtı area. Ore-bearing silica veins exhibit 0.1-0.3 m thicknesses and do not show continuity in the field. Cavity-filling and banded structures are widely observed in mineralizations. The main ore minerals consist of galena, sphalerite, pyrite, chalcopyrite and tetrahedrite, and also trace amounts of gold.Mineral chemistry analyses indicate that pyrite contains low Co and Ni values, Zn displays a negative correlation with Cu and Fe in chalcopyrites, Fe behaves similarly with Cd and Mn in sphalerites and there is an ion exchange between Zn and Fe. In addition, it was determined that all fahlerz minerals are tetrahedrite in composition and silver does not exist in galenas except tetrahedrites.Quartz, sericite, K-Feldspar, kaoline, Fe chlorite, albite, Mg chlorite and epidote are most common alteration minerals from ore towards wall rock. Zr, Hf, Nb, Al and Ti are immobile elements in the profiles that laid out along a line perpendicular to the vein. Relative (%) and net (g/100g) mass change calculations done considering these immobile elements indicated mass gains in 1, 3 and 5 numbered profiles, mass losses in 2 and 4 numbered profiles.Homogenezation temperatures measured from fluid inclusions are between 130°C -295 °C in quartz and 90°C -133°C in sphalerites. In NaCl±KCl±MgCl2-H2O system, ore-forming fluids have salinities between 0.7 and 12.4 wt. % NaCl eq and densities between 0.79 and 0.97 g/cm3. These values reveal that minerilazations were generated in an epithermal system. Sulphur isotope analysis results obtained from pyrite, galena and sphalerite minerals are between -1.2 ? and 3 ?, marking magmatic origin for sulphur. The average heat of formation was calculated as between 244°C and 291°C by sulphur isotope thermometry. Oxygen and hydrogen isotope values are between 15.0 ?-16.7 ? and -87 ? -91 ?, respectively.