Depletion and refertilization of the Tethyan oceanic upper mantle as revealed by the early Jurassic Refahiye ophiolite, NE Anatolia—Turkey

article i nfo We present new whole-rock major and trace element, Re-Os isotope and mineral chemistry data for the upper mantle peridotites and mafic rocks in the Rehafiye ophiolite in NE Anatolia (Turkey), and discuss their signifi- cance for the mantle evolution in Neotethys. The Refahiye peridotites include clinopyroxene (cpx)-rich and cpx-poor harzburgites. Assuming an initial fertile mantle composition, the cpx-rich harzburgites have a limited range of Cr-spl Cr# (33-38), implying 14-18% melt extraction. However, TiO2 contents of the Cr-spl in these rocks are too high (up to 0.24wt.%) to explain their Ti concentrations with a simple melt extraction model in a mid-ocean ridge (MOR) setting, and suggest re-crystallization from an impregnating fertile melt. The interstitial phases of cpx in these samples have high TiO2 (up to 0.40wt.%) and Na2O (up to 0.25wt.%) contents. They also contain interstitial pargasitic amphibole with TiO2 contents varying between 0.69 and 0.88wt.%. These textures and the mineral chemistry data indicate refertilization of the previously depleted, MOR-type peridotites by percolating hydrous melts. The whole-rock REE partial melting modeling is consistent with slightly lower degrees of mantle melting (~12-14%)compared to the melt extraction degrees obtained from the Cr-spl compo- sitions(~15%).Chromianspinel(Cr-spl)phasesinthecpx-poorharzburgitesshowawidervariationofCr#,rang- ing between 57 and 75, and reflect 30-40% of partial melting. In contrast, the whole-rock geochemistry of these rocks represents slightly lower degrees of partial melting, varying between 30 and 35%. The enrichment of TiO2 contentsoftheCr-spl(upto0.20wt.%)insomeofthecpx-poorharzburgitescanbeexplainedbytheirinteraction