Geochemical and sr-nd-pb isotope characteristics of the miocene to pliocene volcanic rocks from the Kandilli (Erzurum) area, Eastern Anatolia (Turkey): ımplications for magma evolution in extension-related origin

Abstract

This paper presents Sr-Nd-Pb isotopic and whole-rock geochemical data of Miocene to Pliocene volcanic rocks in the Eastern Anatolia (Turkey) aiming to unravel their sources and evolutionary history. The wide compositional range of lavas and pyroclastics includes basaltic andesite, basaltic trachyandesite, trachyandesite, andesite and trachydacite. These calc-alkaline volcanics are enriched in large ion lithophile elements and light rare earth elements and depleted in the high field strength elements. Sr-Nd isotope data indicate low values, for Sr-87/Sr-86((i)) (0.70432-0.70464) and high values for Nd-143/Nd-144((i)) (0.51272-0.51282). Further, these data are within the mantle array of the isotope ratio diagram. The lead (Pb) isotopic compositions (Pb-206/Pb-204((i)) = 18.33 to 18.62, Pb-207/Pb-204((i)) = 15.51 to 15.60, Pb-208/Pb-204((i)) = 38.10 to 38.45) reveals the presence of an enriched source. The main petrological processes involved fractional crystallization and the mixing of at least two fractionated magmas having same source characteristics. All evidence supports the findings that the Kandilli volcanic rocks were derived from a partial melting of the both spinet and garnet bearing subcontinental lithospheric mantle, which had been previously metasomatized by mostly fluids derived from subducted slab during the collisional and post-collisional extension-related geodynamic setting in the Eastern Anatolia region of Turkey.