Structure, sedimentation, and basin dynamics during rifting of the Gulf of Suez and north-western Red Sea

Abstract

The Gulf of Suez formed as the northern segment of the late Oligocene-early Miocene Red Sea rift. Rare occurrences of basaltic dikes that cut and flows that are interstratified with the oldest syn-rift strata, a basal red bed sequence (Abu Zenima-Nakheil formations), suggest that rifting had initiated prior to ∼25 Ma. The oldest palaeontologically datable strata are of Aquitanian age (Nukhul Fm.), and are older than ∼21 Ma. Nearby basal strata in north-west Saudi Arabia are Chattian age (∼27 Ma). Apatitie fission-track data suggest that the earliest phase of Gulf of Suez and northern Red Sea rifting may have begun ∼34 Ma, but there is no dated sedimentary record of this. The areal distribution of the basal syn-rift units was largely controlled by the geometry and timing of movement of the early rift-fault system, which was strongly influenced by pre-existing structures in the Pan-African basement complex. In the early Burdigalian, the Gulf of Suez and northern Red Sea entered a period of rapid subsidence and increase in marine water depths, resulting in the widespread deposition of Globigerina marls (Rudeis and Kareem formations) in axial areas. Fault density decreased during the Burdigalian to Langhian, and most extension was accommodated by movement on a few large, basin- or block-bounding faults. By the Serravalian, connection between the Gulf of Suez and Mediterranean basins became restricted and sedimentation rapidly changed to laterally continuous evaporites (Belayim and South Gharib Formations). In the late Tortonian, renewed influx of normal marine water occurred from the southern Red Sea, and deposition switched to mixed evaporite-marginal marine settings (Zeit Fm.). The Zeit sediments differentially loaded the underlying South Gharib massive salt, driving diapirism and intra-sediment slump faulting that were generally focused along Middle Miocene fault trends. Basinal sedimentation patterns during the Messinian, Pliocene and Quaternary were largely controlled by the geometry of the evolving salt ridges. Subsidence became increasingly focused along the axis of the rift during this time.