Dechipering the evolution of the Sahili and Turgutlu granites, Menderes Massif, western Turkey using the electron microprobe, ion microprobe and cathodoluminescence

The Menderes Massif, western Turkey is a large scale metamorphic core complex. This study focuses on determining the timing of movement along one of the main exhumation mechanisms of the Menderes Massif: the Alasehir Detachment. To address the timing of extension, granodiorites samples (S-type, peraluminous) were collected from two outcrops along the Alasehir detachment, located near the towns Salihli and Turgutlu. Monazite (CeLaTh)PO4 within the granites were dated in situ (in thin section) with an ion microprobe using Th-Pb iotopes. To better understand the monazites ages x-ray element maps, geochemical data and cathodoluminescence (CL) images of the dated samples were obtained.;Th-Pb ages range from the Late to Early Miocene, which indicate that the massif has undergone multiple stages of extension. The CL images provided evidence of fluid flow that indicate dissolution/reprecipitation reactions and document a multistage tectonic history. Geochemical data suggests that the Salihli and Turgutlu granites may have been generated under a compressional regime due to north dipping subduction of the Eastern Mediterranean floor along the Hellenic trench. The major and trace element geochemistry show differences between the two granites; which could indicate that the Salihli and Turgultu granites do in fact have different sources, degree of alteration and interaction with fluids, duration and number of tectonic events experienced by the granites, even their P-T history. Data (ages, CL imagery, and geochemistry) collected from the monazites in the Salihli and Turgutlu granites for this study has been reported here and indicate consistency with extension initiating in the Menderes Massif due to subduction roll back. However, problems do arise in linking the ages from the granites to a specific tectonic event due to presence of complex textures, generations of mineral growth, and multiple episodes of deformation.