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.