Exhumed fault scarps and drainage modification as proxies of neotectonics at the Abu Dabbab area, Eastern Desert, Egypt

Abstract

The basement rocks, Neogene sediments and Quaternary alluvial deposits in the Abu Dabbab area, Eastern Desert of Egypt, are deformed by N-S, NE-SW, NW-SE and E-W trending faults. Complex cross-cutting relationships show a complicated history of initiation and reactivation of these faults. The recent fault scarps demonstrate different morphologies, modes of formation and relative ages. Recurrent, step and successively reactivated faulting was likely responsible for the exhumation and neo-formation of the fault scarps. Capture, deep incision, offset and reversal in flow direction of streams are the main drainage modifications induced by active faults. The concealed and active faults are associated with high drainage density anomalies. Segmentation phenomenon is common for all fault trends. Microearthquakes are concentrated at the intersection zones of faults and caused by upper crustal strike-slip, oblique-slip, reverse and normal faults. The paleostresses are not consistent with the present-day stress fields. The present-day NE-SW extension across the Red Sea combined with a local multidirectional tension led to reactivation of old faults and initiation of new fault trends.