Petrographical, geochemical and petrological investigation of the gündoğdu and boğali granitoids (NE-Turkey)

Geochemical and petrological features of the Upper Cretaceous Gündoğdu and Upper Cretaceous-Lower Paleocene Bulbous Granitoids, which are located in the eastern Black Sea Mountains in the eastern Pontide Tectonic Union, are evaluated in this study. The Gündoğdu Granitoid samples are composed of quartz, plagioclase (An2.67-90.42), orthoclase (Or65.00-99.00), amphibole (Mg#: 0.63-0.74) and opaque minerals. The specimens of the Boğalı Granitoid are composed of orthoclase (Or75.20-96.30), quartz, plagioclase (An11.42-66.28), amphibole, biotite (Mg#: 0.73-1.00) and opaque minerals. According to the geochemical data, Gündoğdu Granitoid is characterized by high K and calc-alkaline and I type, whereas Boğalı Granitoid has high K-shoshonitic, calc-alkaline and I type properties. The directions observed in the Harker's diagrams show that the differentiation of plagioclase ± hornblende ± biotite ± magnetite, Ti-oxide and apatite plays an important role in the development of rocks belonging to both of the granitoids. The parent rocks and enclave samples of Gündoğdu and Boğalı Granitoids show considerable enrichment in the large-ion lithophile elements (LILE) and the high field strength elements (HFSE) in the trace element variation diagrams normalized to the primitive mantle. In the variation diagrams normalized to the chondrite of the samples, the light rare earth elements (LREE) are enriched more than the heavy rare earth elements (HREE). It can be assumed that the magma forming granitoids, which tectonically resemble arc granitoids, develops from a hybrid primary magma formed by mafic under-crust-derived melt and sub-continental lithospheric mantle-derived melts.