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

By

 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.