Whole-rock and mineral chemistry of mafic cumulates from the Low-Ti ophiolite in the southern part of Kahramanmaras, Turkey

Abstract

A Late Cretaceous dismembered ophiolite unit in the south of Kahramanmaras belongs to the Peri-Arabian ophiolite belt in southern Turkey. The ophiloitic rocks include, from bottom to top, metamorphic sole (plagioclase-amphibole schist and plagioclase amphibolite), mantle tectonites (serpentinized dunite and harzburgite), ultramafic cumulates (mainly websterite), mafic cumulates (olivine gabbro, gabbro, and olivine gabbronorite), and isotropic gabbros (olivine gabbronorite). The whole-rock geochemistry of the cumulates suggests that they can mainly be classified as Low-Ti ophiolite and derived from an island arc tholeiitic magma source. Chondrite normalized REE and N-MORB normalized multielement patterns and tectonomagmatic discrimination diagrams show that fractional crystallization was important during the formation of the cumulate rocks. The presence of highly magnesian olivines (Fo78.24–81.89), clinopyroxenes (Mg#71.46–85.82), and orthopyroxenes (Mg#62.63–87.18) as well as highly calcic plagioclases (An81.88–97.40) in the mafic cumulates indicates a subduction-related tectonic environment. The geochemical, petrographical, and field data suggest that the ophiolitic rocks in the studied region formed in a suprasubduction zone environment in the southern branch of Neotethys in the Late Cretaceous.