Sedimentation and Early Rift Development in the Northwest Red Sea and Gulf of Suez

B. H. Purser, F. Orszag-Sperber, J. C. Plaziat

Late Oligocene and early Miocene strike-slip and vertical displacement created a system of structural depressions and highs which strongly influenced the localization of continental, protorift sediments. Alluvial fans prograded along grabens, generally oriented obliquely to the rift axis. These initial sediments, together with underlying prerift basement, were subsequently deformed, the resulting system of structural highs and lows influencing the mineralogy and geometry of the succeeding lower Miocene marine sediments. Lows oriented obliquely with respect to the rift axis continued to function as depocenters for siliciclastic marine-fan sedimentation. Other half-grabens oriented parallel to the axis trapped detritals, permitting carbonate sedimentation along the seaward ide of the adjacent blocks. Carbonates accumulated as reefs concentrated along the margins of small structural platforms and as spectacular talus deposits on nearby flanks. These slope deposits prograded at variable rates which depend on both the angle and its orientation with respect to the onshore paleocurrent direction. The relationship between tectonic blocks and contemporaneous sedimentation, relatively intimate during the early phases, gradually becomes more remote as the carbonate slopes prograde asymmetrically with respect to the initial structural axes.

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