Morphotectonics of Kid drainage basin, Southeastern Sinai: A landscape evolution coeval to Gulf of Aqaba – Dead Sea rifting

Abstract

The Pleistocene fluvio-tectonic conditions have shaped the landscapes of Sinai Peninsula through development of small sedimentary traps following preexisting lineaments. In the Gulf of Aqaba region, orientation of these lineaments with respect to the Pleistocene stress field develops strike-slip simple and dip-slip pure extensional shear models that induced rifting of the Gulf of Aqaba – Dead Sea fault system. The Beida and Nabq grabens are two major rift-related depressions at the southwestern coast of the Gulf of Aqaba region. Both grabens are landscapes that received alluvial sediments of the Kid drainage basin (KDB), which is one of the largest drainage systems in the western region of the Gulf of Aqaba fault-scarp. The Beida graben is formed at a horse tail structure next to Abiad and Kid faults, while the Nabq graben is a pull-apart structure formed as onshore continuation of the Dakar deep. The geometry and origin of these landscapes are the intrinsic themes of this study to investigate the morphotectonic evolution of the KDB terrain within the tectonic framework of the Gulf of Aqaba – Dead Sea rift.The hanging terraces and canyons being at higher elevations on the Gulf of Aqaba fault-scarp; and the accumulation of younger alluvial fans, talus cones and bajada on its footslope indicate that the KDB landscape is basically shaped; and evolutionary modified by hinterland uplifting of the Gulf of Aqaba region. Hence, two morphotectonic evolution periods of the KDB terrain coincide with the early NE- and late NNE-trending extensional Pleistocene axes. The early period started with deposition of the older alluvial fan sediments that emerged at the outlet of KDB, and partially buried the Gulf of Aqaba fault-scarp. Subsequent hinterland uplifting revived the Gulf of Aqaba fault-scarp with development of hanging alluvial and bed-rock terraces; and the older alluvial fan sediments are uplifted on the footwall of southward-dipping normal faults whose hanging-wall received sediments of younger alluvial fans. Nature of the sediments constituting the Quaternary paleolakes and rift-related depressions, and their structural settings in Sinai, indicate that the Sinai terrain is basically shaped by crustal uplifting of the southern Sinai massif with severe rifting at the Gulf of Aqaba region.