U-Pb and Sm-Nd geochronology of the Kizildag (Hatay, Turkey) ophiolite: implications for the timing and duration of suprasubduction zone type oceanic crust formation in the southern Neotethys

The Kizildag (Hatay) ophiolite in Turkey represents remnants of the southern Neotethyan ocean and is characterized by a complete ocean lithospheric section. It formed in a fore-arc setting above a N-dipping intraoceanic subduction zone, and represents the undeformed, more northerly part of the same thrust sheet that also forms the Baer-Bassit ophiolite to the south. The ophiolite was emplaced southwards from the southerly Neotethyan ocean in Maastrichtian time. U-Pb and Sm-Nd dates are used to constrain the crystallization age and duration of magmatic activity of the Kizildag ophiolite. U-Pb dating yielded ages of 91.7 +/- 1.9 Ma for a plagiogranite and 91.6 +/- 3.8 Ma for a cumulate gabbro. The cumulate gabbro also yielded a Sm-Nd isochron age of 95.3 +/- 6.9 Ma. The measured ages suggest that the oceanic crust of the Kizildag ophiolite formed in a maximum time period of 6 Ma, and that the plagiogranite may have formed later than the gabbroic section. The U-Pb zircon ages from the Kizildag ophiolite and the cooling age of a metamorphic sole beneath the Baer-Bassit ophiolite are indistinguishable within the analytical uncertainties. This indicates the presence of young and hot oceanic lithosphere at the time of intraoceanic subduction/thrusting in the southern Neotethys. The U-Pb zircon ages from the Kizildag, the Troodos and the Semail ophiolites overlap within analytical uncertainties, suggesting that these ophiolites are contemporaneous and genetically and tectonically related within the same Late Cretaceous southern Neotethyan ocean.