Structural Setting and Tectonic Evolution of the Gulf of Suez, NW Red Sea and Gulf of Aqaba Rift Systems

Abstract

Crustal separation of Arabia from Africa formed a NNW-SSE oriented continental rift in the Gulf of Suez and Red Sea and a NNE-SSW oriented transform in the Gulf of Aqaba. The three regions typically form triple junction at the southern tip of Sinai Peninsula, with the Gulf of Suez form the failed arm. Continental rifting started in the late Oligocene and continued afterwards. Four mega-half grabens of opposite tilt directions are recognized in the Suez Rift and the northwestern part of the Red Sea. Pre-rift structures controlled the locations and orientations of the accommodation zones between these mega-half grabens. The onset of rifting is marked by the deposition of Oligocene red beds followed by Early Miocene basaltic volcanicity in the form of dikes (mostly oriented NNW-SSE) as well as sills and flows. Deposition of the proper syn-rift sediments started in the Aquitanian with a phase of slow tectonic subsidence followed by a phase of rapid subsidence at ~20 Ma. This phase was followed by another phase of slow tectonic subsidence at ~17 Ma that lasted to the Recent time in the Suez Rift marking its abandonment and onset of movement on the Dead Sea Transform. Movement on the Dead Sea Transform aborted extension in the Suez Rift and led to continued opening of the Red Sea Basin. Being close to the Red Sea and the Dead Sea Transform, the southernmost part of the Suez rift witnessed another phase of rapid tectonic subsidence during the last 10 million years. Continued rotation of tilted fault blocks in the southern part of the Suez rift and in the NW Red Sea led to decrease in the dip angles of the main-bounding faults where they got locked and dissected by younger (second-generation) faults. The total slip on the Dead Sea Transform is 105–107 km leading to increase in the width of the Red Sea. The northern part of the Red Sea has highly attenuated continental crust as far south as the Zabargad Fracture Zone whereas seafloor spreading took place in the central and southern parts of the Red Sea. Left lateral slip on the Dead Sea Transform led to opening of the Gulf of Aqaba as a series of connected pull-apart grabens between the overlapping ends of left-lateral strike-slip faults. Total subsidence of these pull-apart basins is in the order of 4–5 km.