TURKISH JOURNAL OF EARTH SCIENCES, cilt.13, sa.1, ss.37-61, 2004 (SCI-Expanded)
Pan-African basement rocks and the Palaeozoic cover series of the Menderes Massif are exposed around Derbent (Alasehir) in the eastern part of the Odemis-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 Pb-207/Pb-206 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