Geochemical and Pb-Sr-Nd isotopic constraints indicating an enriched-mantle source for late Cretaceous to early Tertiary volcanism, Central Anatolia, Turkey

Abstract

Bulk-rock major, trace, and REE geochemistry and Pb-Sr-Nd isotopic compositions identify mantle sources involved in the genesis of volcanic rocks of the Upper Cretaceous-Lower Tertiary Ulukisla Formation, Camard-Ulukisla Basin, Nigde Province, central Anatolia. Incompatible trace-element patterns exhibit a large Nb-Ta trough and strong enrichment of LILE such as Ba, Th and U, and LREE, which indicate a subduction-zone signature. Trace-element ratios are compatible with a subcontinental lithospheric source. Isotopic data demonstrate the presence of an EMII-like protolith (Sr-87/Sr-86 = 0.707242-0.707582, Nd-143/Nd-144 0.512336-0.512390, Pb-206/Pb-204 = 18.70-18.917, Pb-207/Pb-204 = 15.716-15.796, Pb-208/Pb-204) 39.157-39.45). These geochemical and isotopic data indicate the derivation of the studied volcanic rocks from an enriched subcontinental mantle source, modified by earlier subduction events. This petrogenetic conclusion is compatible with a geodynamic setting of post-collisional extension for the Camard-Ulukisla Basin.