Tectono-sedimentary development of early syn-rift sediments during rift-initiation: the Southern Duwi Sub-basin, West Quseir, NW Red Sea, Egypt

This work uses integrated sedimentological and sequence stratigraphy, as well as the impact of allocyclic controls, to investigate the tectono-sedimemtary development of the early syn-rift sequences during rift-initiation at the Southern Duwi half-graben, NW Red Sea, Egypt. The sedimentary fill records a succession dating from Late Oligocene to Early Miocene ( Nakheil and Abu Ghusun formations) and is subdivided into 19 lithofacies organized in major 4 facies associations (FA1 to FA4). These facies associations are arranged in four depositional sequences (DSQ-1 to DSQ-4); these are related to four distinct stages in the history of the early syn-rift evolution of the subbasin. DSQ-1 and DSQ-2, which contain fluvial and lake deposits, are thickest in the centres of small isolated, hangingwall depocentres that developed in response to growth of the two basin-bounding fault segments. DSQ-3 marks the onset of widespread fluvio-lacustrine sedimentation, deposited in a longitudinal, shallow hanging wall depocentre. DSQ-4 is represented by lake dolomite and fan-delta deposits. Facies architecture and the evolution of depositional patterns were controlled by the growth and linkage of a segmented normal fault zone Two main stages are recorded: the folding stage and the coexisted surface-faulting and folding stage. Vertical variations of textural and mineralogical characteristics of these deposits are attributed to provenance from which these detritus were derived. Additionally, the overall evolution of the sequence was palaeclimatically controlled, indicating that the evolution of North African monsoons and drifting were responsible for a general increase in global warming and drying trends.