Tectono-Stratigraphic Development of the Neogene Gulf of Suez Rift Basin

Mark Richardson, Michael A. Arthur

Subsidence analysis (backstripping) was carried out on a series of wells from the Gulf of Suez and northern Red Sea region of Egypt in order to examine the interplay between tectonic events, basin subsidence, sedimentation, and sea level changes in a young, developing ocean basin and continental margin. Using constraints on chronostratigraphy and paleodepth from various sources combined with stratigraphic and structural information from industry wells and other geophysical sources, it has been possible to compile the data necessary to perform geohistory analyses throughout the region.

Major subsidence due to crustal thinning began ~25 Ma, with sedimentation initially occurring in isolated subbasins. These earliest sediments record the transition from continental to marine depositional environments. Subsequently during early and middle Miocene time, subsidence was rapid and uniform along and across the entire rift basin. Open marine sedimentation occurred across all structural regimes. There is no evidence of south-to-north propagation in the timing of rifting in the northern Red Sea-Gulf of Suez basin. The mid-Clysmic tectonic event (16.5 Ma) resulted in structural rearrangement of the rift basin and uplift of the rift shoulders. Rapid subsidence continued as global sea level fell, producing a series of prograding, siliciclastic fan-deltas as the rift margins. At ~ 5.5 Ma, opening of the Suez rift was terminated, and tectonic subsidence decreased dramatically in the southern rift and ceased entirely in the northern rift. Tensional plate motion probably was transferred from the Gulf of Suez to sinistral strike-slip movement on the Dead Sea transform at this time. The quiescence in subsidence, combined with a lowered global sea level, resulted in the deposition of a thick (up to 4 km) series of evaporites almost exclusively within the central trough of the rift from the middle to latest Miocene. The accumulation of such a thick sequence of sediments during a phase of decreased tectonic subsidence is interpreted as a "filling-in" of the rift topography which developed during the earlier period of rapid subsidence and rift-shoulder uplift.

A rapid global sea level rise concomitant with a subsequent pulse of increased tectonic activity in the latest Miocene-earliest Pliocene returned the rift to dominantly marine conditions.

AAPG Search and Discovery Article #91032©1988 Mediterranean Basins Conference and Exhibition, Nice, France, 25-28 September 1988.