Petrographical, geochemical and petrological investigation of the Kiliçkaya (Bayburt) granitoid

In this study, mineralogical-petrographical composition, mineral chemistry and whole-rock geochemical characteristics of Kılıçkaya Granitoid in the Kılıçkaya (Bayburt) area were determined, and the evolution and origin of plutonic rocks were investigated. The studied area located on the northern zone in the eastern Pontide. The basement is represented by Eocene aged andesite and pyroclastics. This unit are cut by the Eocene Kılıçkaya Granitoid and are overlie uncorformably by Quaternary alluvium. The granitoid rocks are medium to coarse grained, and composed of plagioclase, ortoclase, quartz, hornblende, biotite, apatite, zircon and opaque minerals. The Kılıçkaya Granitoid is elipse shaped, and settled approximately in an area of 18 km2. It consists of diorite, granodiorite and tonalite, and includes abundant wall-rock xenoliths and dioritic mafic magmatic enclaves (MME). The Kılıçkaya Granitoid shows disequilibrium textures showing magma mixing. The Kılıçkaya granitoid is generally I-type, high-K calc-alkaline character, and has high SiO2 (58-67 wt.%) contents. The samples has metalüminous characters and enriched in large ion lithofile elements. Chondrite normalized REE patterns are concave shaped (LaN/YbN=17.14-8.72), and show slightly negative Eu-anomalies (EuN/Eu*=0.64–0.91). Major and trace element variations indicate significant role of plagioclase, hornblende and Fe-Ti oxide fractionation during the evolution of rocks. All these properties, low (Al2O3)/(MgO+FeOT), K2O/Na2O, ASI, (Na2O+K2O)/(FeOT+MgO+TiO2), (Al2O3)/(FeOT+MgO+TiO2) and high (CaO+FeOT+MgO+TiO2), (Na2O+K2O)/(FeOT+MgO+TiO2), (Al2O3+FeOT+MgO+TiO2) values indicate that magma generation by dehydration melting of an amphibolite-type lower crustal component with additional input of a subcontinental lithospheric mantle component.