Crystal fractionation of adakitic magmas in the crust-mantle transition zone: Petrology, geochemistry and U-Pb zircon chronology of the Seme adakites, eastern Pontides, NE Turkey

► This is the first comprehensive study on the Seme adakites exposed in the southern part of the eastern Pontides orogenic belt. ► Based on major, trace and REE geochemistry, we demonstrate that high-pressure fractional crystallization process played an important role in the petrogenesis of the Seme adakitic magmas. ► We also present new zircon U-Pb geochronology in order to determine precise timing of the adakitic activity in the Seme area. ► We also discuss the geodynamic models suggested by Dilek et al. (2010), Karsli et al. (2010) and Topuz et al. (2005) for the origin of eastern Pontide adakitic rocks in the light of our detailed field, geochemical, isotopic and geochronological data obtained from 137 adakitic bodies exposed seven different domains in entire eastern Pontide orogenic belt. ► We claim that the eastern Pontide adakitic rocks were generated by slab window processes during ridge subduction in a south-dipping subduction zone.