Petrogenesis of pillow lavas based on mineralogical and geochemical data in the eastern part of Sabzevar ophiolite

Sabzevar ophiolitic pillow lavas contain variolitic, porphyritic with microlitic matrix, intersertal and amygdaloidal textures and include plagioclase, clinopyroxene (augite-diopside), olivine, amphibole (magnesiohastingsite) and opaque minerals. The chemical composition of clinopyroxenes show a calc-alkaline magmatic series and a tectonic environment within plate alkaline basalts. Geochemically, these rocks are divided into two groups. Group 1 is basically calc-alkaline andesite with low TiO2 and group 2 is alkali basalt with high TiO2. N-MORB normalized trace elements diagram shows that group 1 is enriched in Th, U, La and depletion in Ta, Nb, Ti and group 2 is enriched in Th, Ta and Nb. Calc-alkaline rocks have produced in a subducted tectonic environment by a continental crust and erupted southwards on the Turan plate. In contrast, alkaline rocks formed within plate oceanic and then tectonically accreted in the forearc setting.