STRUCTURAL EVOLUTION OF NORMAL FAULTS CONTROLLING THE NORTHERN AND SOUTHERN MARGINS OF THE CENTRAL MENDERES METAMORPHIC CORE COMPLEX, WESTERN TURKEY
2D seismic profiles in the Alaºehir and Buyuk Menderes Grabens show well developed rollover structures indicating that the sediments in the two grabens were folded and faulted as the central Menderes metamorphic core complex formed during the Cenozoic Crustal extension in western Turkey. The Miocene sedimentary succession on the hanging wall of the Alaºehir and Buyuk Menderes Detachment Surfaces contain two sets of normal faults that are younger than the Detachment Surfaces. The first set dip 35-50 degrees to the north and south, respectively. The second and the youngest set dip 60-75 degrees north and south, respectively. The rollover structures in the Alaºehir and Buyuk Menderes Grabens also contain superimposed folds with N20E to N30E striking fold axial planes. The Alaºehir Detachment surface also contains a well developed Turtleback fault surface similar in its geometry to the Death Valley Turtleback surfaces in southwestern Basins and Ranges. The Turtleback is a folded detachment surface with a northerly trending fold axial plane parallel to the superimposed folds.
The evidence outlined above suggest that both Alasehir and Buyuk Menderes Detachment surfaces were formed as oppositely dipping high angle normal faults and then were rotated to shallower angle due to flexural bending/rolling hinge processes that were effective during the Cenozoic exhumation of the Central Menderes Metamorphic Core Complex.