Geochemistry of the Middle Miocene Collision-related Yamadagi (Eastern Anatolia) Calc-alkaline Volcanics, Turkey

Major, trace element and K-Ar age determinations are reported for a suite from the Yamadagi volcanics in the Eastern Anatolia. The exposed rocks mainly consist of medium-potassium calc-alkaline basaltic andesites, andesites and dacites. Petrographical data exhibit disequilibrium mineral textures, such as resorption of the ferromagnesian phases, clinopyroxene-mantled orthopyroxene, and sieve-textured plagioclases. The Yamadagi volcanics have a calkalkaline character, and trace element characteristics exhibit that the volcanics resemble subduction zone volcanics and/or volcanics assimilated by continental crust. K/Ar age determinations show that the Yamadagi volcanics were formed during the 12 +/- 0.5 - 15 +/- 0.5 Ma time interval. Geochemical characteristics of these volcanics can be attributed to complex petrogenetic processes, including magma mixing and crustal assimilation along with fractional crystallization.