Geochronology, geochemistry, genesis and geodynamic evolution of porphyry intrusions and associated porphyry-epithermal polymetallic mineralization in the area of kiziltoprak tepe (Gümüşhane, kd Türkiye)

The aim of this thesis is to shed light on the timing, conditions, and origin of the Kızıltoprak Tepe mineralization (Yağmurdere, Gümüşhane) associated with a complex magmatic-hydrothermal system, along with elucidating the evolution of magmatic and hydrothermal events within this system. For this purpose, a multidisciplinary analytical approach, including various geochronological, geochemical, and isotopic analyses alongside field and laboratory studies, has been applied. Geological, mineralogical, geochemical, and isotopic data indicate that the mineralization (molybdenite Re-Os: ~43 Ma) is associated with middle-late Eocene (zircon U-Pb: ~45-40 Ma) calc-alkaline/metaluminous, adakite-like and Mg-rich andesitic-dacitic porphyries. These ore-bearing porphyries were derived from a hybrid melt formed by assimilation and/or mixing processes of metasomatized mantle-derived Mg-rich basaltic melts with lower crust in a slab break off-related tectonic setting, and then their evolution in a water and oxygen-rich magma chambers under shallow crustal conditions. Based on the ore-related data, it is concluded that the mineralization occurred in two main stages: (i) an early stage characterized by a porphyry Au±(Cu-Mo)-type and (ii) a late stage marked by an epithermal-type with intermediate sulphidation including base (Pb-Cu-Zn) and precious metals-rich (Au, Ag, As, Sb, Bi, Te) ores; and also that the hydrothermal fluids are predominantly of magmatic origin with variable temperatures and salinities.