Late Cenozoic cooling history of the central Menderes Massif: timing of the Büyük Menderes detachment and the relative contribution of normal faulting and erosion to rock exhumation

Wölfler A, Glotzbach C, Heineke C, Nilius N.-P, Hetzel R, Hampel A, Akal C, Dunkl I, Christl M.

Zusammenfassung

Based on new thermochronological data and 10Be-derived erosion rates from the southern part of the central Menderes Massif (Aydın block) in western Turkey, we provide new insights into the tectonic evolution and landscape development of an area that undergoes active continental extension. Fission-track and (U-Th)/He data reveal that the footwall of the Büyük Menderes detachment experienced two episodes of enhanced cooling and exhumation. Assuming an elevated geothermal gradient of ~50 °C/km, the first phase occurred with an average rate of ~0.90 km/Myr in the middle Miocene and the second one in the latest Miocene and Pliocene with a rate of ~0.43 km/Myr. The exhumation rates between these two phases were lower and range from ~0.14 to ~0.24 km/Myr, depending on the distance to the detachment. Cosmogenic nuclide-based erosion rates for catchments in the Aydın block range from ~0.1 to ~0.4 km/Myr. The similarity of the erosion rates on both sides of the Aydın block (northern and southern flank) indicate that a rather symmetric erosion pattern has prevailed during the Holocene. If these millennial erosion rates are representative on a million-year timescale they indicate that, apart from normal faulting, erosion in the hanging wall of the Büyük Menderes detachment fault did also contribute to the exhumation of the metamorphic rocks.