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Syn-Rift Stratigraphy and its Record of Structural Evolution in the Central Suez Rift, Egypt


 David A. Pivnik1, Jay Thorseth1, Mohamed Ramzy2

(1) BP, Houston, TX (2) Gulf of Suez Petroleum Co, Cairo, Egypt

 We used syn-rift stratigraphy to determine the evolution of major normal-fault bounded structural blocks in the central Suez Rift, Egypt. For each block, we used the difference between hanging wall and footwall gross-interval thickness for each biostratigraphically defined syn-rift sequence as a proxy for fault displacement during deposition of that sequence.

Sequence-20 (Mheiherrat Fm.), generally recognized as the “rift-climax” stage, saw maximum sediment thickness, sandstone thickness, sedimentation rate, fault-displacement and fault-displacement rate. These parameters generally decrease in the overlying syn-rift sequences, and in the underlying Sequence-10 (Nukhul Fm., early rifting).

Point sources for coarse-clastic material were located at both ends of the Morgan transfer zone, which separates the region into 2 dip provinces (SW dipping faults north of the transfer zone, NE dipping faults to the south). The two point sources were established and also peaked during Sequence-20 deposition, but their contribution of coarse sediment to the basin was episodic.

Bald high blocks, which were raised above sea-level during or soon after deposition, occur near the rift margins, but also in the basin center during early (Sequence-10) and late (Sequence-55, Belayim Fm.) rifting. High displacement-rate faults generally occurred near the basin margins, except for during Sequence-10 deposition, when they were distributed throughout the basin, and during Sequence-55 deposition, when the highest displacement rate fault was in the basin center.