Petrological characteristics of Kızıldağ (Hatay, SW-Turkey) ophiolite, melt-rock interaction and metasomatizm effects in a supra-subduction zone setting

The Kızıldağ ophiolite (Turkey) in the eastern Mediterranean region is a remnant of the oceanic lithosphere that was formed in Southern Neotethys Ocean. We establish some mantle harzburgites, which are represented by distinct chemical and petrographic characteristics. All types of harzburgites have similar spinel Cr#, although the enriched ones have higher TiO2 (0.12-0.57 wt.%) compositions than depleted harzburgites (0.02-0.17 wt.%). Chondrite-normalized rare earth element (REE) patterns of clinopyroxenes (cpx) from the depleted harzburgites show ultra-depleted light REE (LREE) ([Lu/La] N >10) compositions and similarities to the cpx from the oceanic peridotites of normal ridge segments. The cpxs are also enriched in hydrophile elements (e.g., B, Li, U) and depleted in high field strength elements (HFSE e.g., Zr, Nb and Ta). The spinel and cpx REE compositions suggest two melting processes in garnet and spinel stability fields. The heavy rare earth element (HREE) compositions of cpx, combined with the melting models indicate a first stage melting in presence of garnet (~10%) and a second stage melting in spinel field (15%) with a total 25% partial melting rate for the mantle harzburgites of the Kızıldağ ophiolite. Impregnation and melt-mantle interaction traces indicate a supra-subduction zone (SSZ) setting, where LREE and Ti-rich melts and fluids interacted with previously depleted peridotites. Overall, the data show that the Kızıldağ ophiolite possibly represents a multi-stage evolution in MOR and SSZ settings.