Origin of Refahiye ophiolite (NE Erzincan)

The study area, situated in Üzümlü-Çayırlı (Erzincan) region, is characterized by pre-Permian Yoncayolu formation, Permian Çayderesi limestone, Jurassic-Cretaceous Hozbirikyayla formation, tectonically overlying Refahiye ophiolitic melange and unconformably overlying cover sediments, namely Lower-Middle Eocene Gülandere formation and Miocene Kemah formation. Except volcanics, the Refahiye ophiolite in the study area displays an intact ophiolite stratigraphy from bottom to top. Whereas the volcanics are found in melange unit. The base of the Refahiye ophiolite is represented by variably serpentinized harzburgite and dunite. Well preserved ultramafic (dunite, wehrlite, clinopyroxenite) to mafic (gabbro) cumulate rocks rest tectonically on the tectonites. Isotropic gabbros (gabbro, diorite), sheeted dikes (diabase) and plagiogranites constitute the upper part of the Refahiye ophiolite. The volcanic rocks are basaltic in composition and variably altered. On the basis of geochemical analysis, the isotropic gabbros and sheeted dikes were derived from both tholeiitic and boninitic magmas whereas the volcanic were derived from tholeiitic and alkaline magmas. The rocks, derived from tholeiitic and boninitic magmas, were formed in a fore-arc (suprasubduction zone) setting as a result of north deeping intraoceanic subduction zone in the northern branch of Neotethys since late Cretaceous. The alkaline volcanic rocks are not related to the ophiolite formation. But they are more seamount type in origin.