Print this pageTemporal and Spatial Tectonic Controls on Stratal Architecture In a Marine-Dominatsd Rift Basin; Gulf of Suez, Egypt
WESCOTT, WILLIAM A., DAG NUMMEDAL
The character of Miocene synrift deposits filling the Suez Rift is dependent upon where in the rift sedimentation occurred and the stage of rift evolution during deposition. During the earliest phase of rift initiation numerous, small halt-grabens developed and deposition was dominated by northward flowing, axial fluvial systems. Locally, small alluvial fans formed along the footwall margins. With increased subsidence the basin was inundated from the north by marine waters forming estuarine and ultimately open-marine environments. During the clysmic stage of rifting many of the smaller faults became inactive and extension transferred to a few incipient rift-bounding faults resulting in increased subsidence and uplift of the rift shoulders. Initial response to clysmic rifting was relative sediment starvation in the basinal centers because of rearrangement of drainages feeding the rift. Ramp margins of asymmetric half-grabens became the sites of prograding Gilbert-type deltas and associated shallow marine deposits. Sedimentation in the deeper basins was dominated by turbidite and submarine fan deposition. Talus cones that eventually evolved into fan deltas formed along footwall margins. Topographic lows at rift transfer zones became the sites of major coarse-clastic input.
Maximum extension was accompanied by isostatic rebound resulting in a shallowing of the rift. Cessation of active rifting was marked by regional thermal subsidence resulting in a period of overall transgression punctuated by relatively high frequency depositional cycles caused by minor tectonic adjustments and1or sealevel changes. The post-rift stage was characterized by continued thermal and compactional subsidence and dominated by evaporite deposition.