Rheological stratification and spatial variations in the effective elastic thickness of the lithosphere underneath the central Anatolian region, Turkey

Abstract

In this study, the regional components of global model EGM08 Bouguer anomalies obtained by low pass filtering were inverted to map the geometries of Moho and Lithosphere-Asthenosphere Boundary (LAB) of the central Anatolian region. It was determined the Moho and LAB depths in the region to be 35.8–41.2 km and 67–91 km, respectively. The results from rheological modeling indicate mechanical decoupling of the crust and uppermost lithospheric mantle in eastern part and coupling in the western part of the study area. We also compare the rheological stratification with the focal depth distribution of earthquakes to examine the possible discrepancies between the brittle-ductile transition zone and the maximum depths of earthquakes along the selected profiles. The spatial variations of effective elastic thicknesses (EET) of the lithosphere have been estimated from the strength of the crust and lithospheric mantle by implying deformation gradient at Moho and LAB. The EET values vary in the range of 19–24.3 km. Although the EET values are relatively high in the eastern part of the region, lower EET values are directly underlain by thinned lithosphere of northwestern and southwestern part of central Anatolian region. We also analyze the crustal rheologies obtained from the lithospheric strength by delineating the pattern of crustal seismic activities.