SIGNIFICANCE OF MULTI-GENERATION EXTENSIONAL FAULTING AND ROTATIONAL DEFORMATION IN THE LATE CENOZOIC ALASEHIR SUPRADETACHMENT BASIN EVOLUTION, WESTERN ANATOLIA (TURKEY)

Intrabasinal structure and sedimentary record of the Alasehir supradetachment basin (ASDB) provide critical information on the kinematics and dynamics of the Late Cenozoic extensional deformation in western Anatolia. The ~E-W-trending ASDB bisects the Menderes metamorphic core complex (MMC) and takes an important role on its exhumation history. We classify four different fault generations controlling the deposition, internal deformation, and overall basin geometry in the ASDB. The Alasehir detachment fault (F1) is a N-dipping low-angle normal fault separating high-grade metamorphic rocks of the MMC and syn-extensional Salihli granitoid from the Early Miocene-Quaternary basin fill in the hanging wall. N-dipping, low-angle normal faults (F2) within the basin fill and footwall rocks mimic F1 and display a complex crosscutting relationship with high-angle normal faults (F3) along the southern section of the ASDB. Some F3 faults locally offset F1, whereas they are cut by F2 faults at some localities. Basin-parallel F3 faults result in modification of dip angles due to back-tilting and block-rotation mechanisms. N-S-trending deep valleys usually formed as surface expressions of the basin-perpendicular, oblique-slip, high-angle scissor faults (F4). We define 6 scissor fault blocks along the southern section of the ASDB and document orientation changes occurred due to rotational deformation related to F4 faulting. High-resolution satellite images show orthogonal F4 faults blocks accommodating differential uplift and extension rates. Alignment of the Quaternary cinder cones and eruptive centers in the northern section mostly coincides with the intersections of F3 and F4 faults. The Quaternary basalt flows in the Kula volcanic field also appear to follow the orientation of N-S-striking fractures. Crosscutting relationships of four fault generations indicate that high-angle normal faulting was a continuous mode of extension during the late Cenozoic. Local unconformities developed as a result of differential extension and block uplift within the basin. There is no evidence for large-scale contractional folding and for significant changes in the stress regime during the evolution of the ASDB, ruling out the possibility of a pulsed-extension history in the region.