Mid-ocean ridge and supra-subduction geochemical signatures in spinel–peridotites from the Neotethyan ophiolites in SW Turkey: Implications for upper mantle melting processes

The Lycian and Antalya ophiolite complexes in SW Turkey represent fragments of oceanic lithosphere emplaced following the closure of the Neotethys Ocean during the Late Cretaceous. The peridotites from both of these ophiolites have compositions ranging from relatively undepleted lherzolites to highly depleted harzburgites and display a diverse suite of geochemical signatures indicative of both anhydrous, mid-ocean ridge (MOR)-type and hydrous, supra-subduction zone (SSZ)-type melting regimes. Whole-rock major and trace element systematics and mineral chemistry indicate that the MOR- and SSZ-type peridotites represent the residues from 5–9% and 13–25% of mantle melting, respectively, and display evidence for a multi-stage evolution of an oceanic lithosphere. Olivine–orthopyroxene–spinel equilibria indicate that the clinopyroxene-bearing, MOR-type peridotites are moderately reduced with their oxygen fugacity (fO2) ranging from −2.22 to −1.44 log units relative to the FMQ (fayalite–magnetite–quartz) buffer and are similar to abyssal peridotites, while more refractory, SSZ-type harzburgites and dunites (