Petrogenesis and tectonic importance of miocene granites (Ağri-East Anatolia)

Eastern Anatolian Accretion Complex have a huge magmatic activity during Late Cenozoic period. The magmatic activity shows basic geochemical signature. In the region, this research Project aims to explain source characteristics and geodynamic setting of the Demirkapı and Bezirhane plutons. The plutons are made up of granite, syenite, monzonite, quartz monzonite and gabbro. They are rich in mafc microgranular enclaves. The LA-ICP-MS zircon U-Pb age data reveal that Demirkapı pluton crystallized at ages between 22.16  0.20 an 22.86  0.17 Ma and Bezirhane pluton; 22.82  0.19 and 23.33  0.12 Ma. The plutons are of metaluminous to peraluminous and belongs to low-k calc-alkaline to shoshonitic series. The basic Sr-Nd isotope modeling displays that the hybrid magma is generated by mixing of 70-75% of the lower crustal-derived melt with  30-25% of the mantle-derived melt at depths (5-6 km) of lower crust. Then the hybrid melt ascended to shallower crustal level and underwent a limited fractionation process to generate a variety of rock types of the I-type plutons. All the data combined with regional background, we suggest that the plutons were originated in back-arc extensional phase of subduction environment during Early Miocene in the region.