Geochemistry, geochronology and tectonic significance of igneous rocks outcropping in the region between Osmaniye and Kahramanmaraş in the Emanos mountains

The Amanos ophiolite is located on the NE edge of the Arabian platform. It is represented by an incomplete ophiolite sequence, tectonically on the top of the Arabian platform, from bottom to top, namely an ophiolitic mélange, metamorphic sole, mantle tectonites and cumulates. The mantle tectonites contain chromitite occurences surrounded by dunitic envelopes and are cut by individual diabase dykes at different structural levels. Contact relationship between ophiolitic units is tectonic. The Paleozoic clastic sequence, which forms the basis of the Arabian platform in the Amanos Mountains, is unconformably overlain by Mesozoic platform carbonates. Four different mélange types in the study area such as sedimentary mélange, serpentinite matrix mélange, heterogeneous mélange and mud diapir are exist. Amphibolites belonging to the metamorphic sole at the base of the Amanos ophiolite are similar in origin to island arc tholeiites (IAT). These rocks underwent metamorphism in the intra-oceanic subduction zone during the Late Cretaceous (Zircon U-Pb: 94.60±6.62 Ma) at 548 to 571 oC temperature and 4.1 to 5.8 kbar pressure. Whole rock major-trace element and mineral chemistry analyses of mantle peridotites suggest two-stage partial melting; firstly 15-18% partial melting of fertile oceanic mantle (lherzolite) peridotites in the mid-ocean ridge environment during the Late Triassic-Lower Cretaceous period, and secondly ≥25% partial melting of depleted peridotites (harzburgite) in the fore-arc environment in the Late Cretaceous. Chromium spinels in chromitites from the depleted harzburgites are represented by high Cr# (76.65) and TiO2 (%0.21) values and boninitic magma interacted during their genesis. Whole rock parent-trace and mineral chemistry contents of cumulate gabbro and isolated diabase dyke rocks indicates that they are derived from both boninitic magmatism derived from the fore-arc environment and alkaline magmatism from an enriched mantle source resulting from subduction roll-back or rupture of the subducting plate. Lower Miocene basaltic volcanism is the product of both tholeiitic and alkaline magma. Volcanics were formed due to partial melting of the enriched mantle source (garnet and spinel) for alkaline (3-4%) and for tholeiitic-alkaline (8-10%) products. All these events occurred during the opening-closing stages of the S. Neotethyan ocean in the Late Triassic-Miocene period.