Composition and petrology of mantle peridotites of the SE Anatolian orogenic belt ophiolites: Geochemistry of major oxide, trace element, mineral chemistry and Fe, Mg and Os isotopes

Kızıldağ, Koçali and Guleman Ophiolites are the most important ophiolitic massifs of the Southeastern Anatolian Orogenic Belt. The investigation of ophiolitic rocks in this belt is key to explaining the tectonic evolution of Neo-Tethys southern branch in Mesozoic. This study is very important for the determination of the partial melting, melt-rock interaction, metasomatism events and tectonic environment of ophiolites in upper mantle. Therefore, after petrographic studies, geochemical analysis of whole rock main oxide, trace and Lanthanum Group Elements, Os, Fe-Mg isotope analysis performed on whole rock and minerals. The mantle peridotites from the investigated ophiolites are generally represented by high spinel Cr# values, with the Al2O3, CaO and TiO2 contents are depleted compared to the primitive mantle. Geochemical data indicate that the mantle peridotites of the relevant ophiolites are highly depleted, and were formed in forearc region of supra-subduction zone. The enrichments seen in some of the Large Ion Lithophile Elements, High Field Strength Elements and Platinum Group Elements are due to the metamomism of the slab-derived fluids to the mantle wedge. Some Guleman peridotites 187Os/188Os values are higher than primitive mantle, which are explained by the addition of radiogenic Os derived from the sediments in subducting slab. High Fe isotope values are a result of fluids derived from subducted slab increasing the oxygen fugacity. The investigated ophiolites, formed in supra-subduction zone with a northward subduction in the southern branch of Neo-Tethys in the Upper Cretaceous, and overlaid the Arabian plate to the south at the end of the Cretaceous. Keywords: Kızıldağ-Koçali-Guleman Ophiolites, Mantle Peridotites, Partial Melting, Geochemistry, Os Isotope, Fe-Mg Isotope