Geochemical and geochronological evidence for Early Triassic calc-alkalinemagmatism in the Menderes Massif, western Turkey

Pan-African basement rocks and a Paleozoic cover series, which were intrude d by the protoliths of Leucocratic orthogneisses, have been recognized in t he Menderes Massif, located in the western part of the Alpine orogenic belt of Turkey. This geochemical and geochronological study focuses on the evol ution of the Menderes Massif at the end of Paleozoic time. Geochemical data suggest that the crustally derived leucocratic orthogneisses have chemical composition typical of calc-alkaline and S-type granite. Zircon grains whi ch are euhedral with typical igneous morphologies were dated by the Pb-207/ Pb-206 evaporation method. Single-zircon dating of three samples yielded me an Pb-207/Pb-206 ages of 246 +/-5, 241 +/-5 and 235 +/-6 Ma. These ages are interpreted as the time of protolith emplacement in Triassic. Geological a nd geochronological data suggest that leucocratic granites were emplaced in a period following a metamorphic event related to the closure of the Paleo -Tethys. The leucocratic granites were metamorphosed during the Alpine orog enesis and transformed into orthogneisses. The similar Triassic magmatic ev ent at 233 +/-2 Ma was also occurred. using single-zircon evaporation metho d, from granitic gneisses which rest upon the migmatites with tectonic cont acts in Naxos, Cycladic complex. This indicates that the Menderes Massif an d Cycladic complex had a common pre-Early Triassic magmatic evolution.