Tectono-geomorphological evolution of the Northern Red Sea margins

The geodynamic evolution of continental rifts and rifted margins influences petroleum prospectivity. Rift studies have tended to focus on offshore domains, whilst a more holistic approach would also consider sub-aerial data, providing information on rift flank uplift, drainage evolution and sediment routing. The Neogene northern Red Sea rift allows examination of the interaction between geodynamics, tectonics and geomorphology. Here, its tectono-geomorphic evolution is assessed by integrating drainage inverse modelling, drainage analysis, low-temperature thermochronology and structural mapping. On the margin scale, inverse modelling shows an early uplift (~22-15 Ma) in the southern part of the northeastern Red Sea and northern Gulf of Suez margins, and a later uplift (~14-0 Ma) along the northeastern Red Sea/Gulf of Aqaba, Sinai and northern Egyptian Red Sea margins. A smaller scale (20-30 km) study using low-temperature thermochronology and structural mapping reveals that pre-existing structures of suitable orientation do not all show resolvable reactivation during Red Sea rifting. The present-day drainage records the interplay of basement heterogeneities, rift-related uplift and later uplift. North-directed pre-rift drainage was modified forming transfer, hangingwall and footwall catchments. Later uplift reorganised drainage by reversal and capture, changing catchment sizes and relocating catchment outlets. The early uplift is interpreted to have been driven by rifting with possible mantle support and the later uplift was driven largely by transform tectonics and dynamic support by mantle flow. The catchment distribution indicates that early northern Red Sea rifting was accommodated by SW-dipping faults, with polarity changing further north into, and within, the Gulf of Suez. This study benefits from the integration of several datasets, and highlights rift geodynamic complexity and the necessity to integrate surface and subsurface data to constrain sediment pathways for petroleum exploration.