Menderes masifi, Ödemiş-Kiraz asmasifi'nin doğusunda yer alan granitic gnaysların ve lökokratik ortognaysların jeolojisi, jeokimyası ve jeokronolojisi: Pan-Afrikan ve triyas magmatik aktiviteleri

Geological evidence, geochemical compositions and geochronological constraints for a variety rock types from the eastern part of the Ödemiş-Kiraz Submassif of the Menderes Massif are presented and interpreted for the geotectonic evolution of the Menderes Massif. The rock succession of the Derbent and Demirhan areas, in the eastern part of the Ödemiş-Kiraz Submassif of the Menderes Massif is made up of nappe stack. In the vicinity of Derbent, the rock succession of metamorphic series can be divided into four nappe units. In ascending order, the lower, middle and upper nappe units are represented by internal imbrication of the Pan-African basement series. The uppermost nappe units belonging to the Paleozoic-Mesozoic cover series rests tectonically upon the upper nappe units of the Pan-African basement. These metamorphic rocks of the Menderes Massif displaying typical nappe structure, tectonically overlain by unmetamorphosed ophiolitic rocks. Furthermore, in the Demirhan area, metapelites of cover series are overlain by a nappe unit which completely consists of Pan-African orthogneisses. Pan-African basement series consisting of metapelites and phyllites were intruded by the granitic protoliths of orthogneisses. Furthermore, the Pan-African basement rocks and the Paleozoic cover series were also intruded by the granitic precurser of leucocratic orthogneisses. The geological evidences prove the granitic origin of these both orthogneisses. They show original intrusive contact relationship with the country rocks. Geochemical compositions indicate that the protoliths of Pan-African orthogneisses were calc-alkaline, peraluminous, S-type, syn- to post-tectonic granites and granodiorites. Geochemical data also reveal that the crustully derived leucocratic orthogneisses were peraluminous, S-type granites with calc-alkaline affinity. IVThe SEM and CL photomicrographs demonstrate that the analysed zircon populations in Pan-African orthogneisses have distinct magmatic zoning and typical igneous morphology. The 207Pb/206Pb ages of 561.5±1.8 and 570.5±2.2 Ma are interpreted as the intrusion ages of protoliths of the Pan-African orthogneiss. The geological and geochronological data suggest that the granitic protoliths of these orthogneisses were emplaced in a period following a high grade metamorphic event related to the Pan- African orogeny. Zircon grains of leucocratic orthogneisses which are identified as euhedral crystals with typical igneous morphology by SEM and CL studies were dated by the single zircon 207Pb/206Pb evaporation method. Single zircon dating of three leucocratic orthogneiss samples yielded mean ages of 234.9±5.8, 241.1±5.2 and 245.7±4.6 Ma. The geological and geochronological evidence indicate that the leucocratic orthogneisses were intruded into the Pan- African basement and Paleozoic cover series during the Early-Middle Triassic time most probably related to the closure of Paleotethys. Based on the tectonic setting and ages of the syn- to post- tectonic leucocratic orthogneiss, it can be suggested that the closure of the Paleotethys at around Eastern Mediterranean might be taken place during the Latest Permian time. Intrusion of protoliths of the Triassic leucocratic orthogneisses into both of the Pan-African basement and Paleozoic cover units reveals that these two units were tectonically juxtaposed prior to Triassic time.