Geochemistry and Geochronology of Orthogneisses in the Derbent (Alaşehir) Area, Eastern Part of the Ödemiş-Kiraz Submassif, Menderes Massif: Pan-African Magmatic Activity

Authors: ERSİN KORALAY, O. ÖZCAN DORA, FUKUN CHEN, MUHARREM SATIR, OSMAN CANDAN

Abstract: Pan-African basement rocks and the Palaeozoic cover series of the Menderes Massif are exposed around Derbent (Alaşehir) in the eastern part of the Ödemiş-Kiraz submassif. Garnet-mica schists of the Pan-African basement are intruded by the protoliths of orthogneisses and Triassic leucocratic orthogneisses. This study focuses on the geochronology and geochemistry of orthogneisses related to the Pan-African evolution of the Menderes Massif in latest Proterozoic time. Geochemical data suggest that the orthogneisses were derived from S-type, peraluminous, syn- to post-collisional granitoids of calc-alkaline affinity. Zircon grains from the orthogneisses, which are euhedral with typical igneous morphologies, were dated by the Pb-Pb evaporation method. Single zircon ages of two samples yielded 207Pb/206Pb ages of 561.5±1.8 Ma and 570.5±2.2 Ma. These ages are interpreted as the time of protolith emplacement of the orthogneisses. This major magmatic episode of the Menderes Massif can be attributed the Pan-African Orogeny which was related to the closure of the ocean basins and amalgamation of East and West Gondwana.

Keywords: orthogneiss, geochemistry, Pb-Pb zircon dating, Pan-African, Menderes Massif, Turkey

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