Rift Border Fault
System Evolution and Impact on
Sedimentation, Southwestern Gulf of Suez, Egypt
By
Mohamed S. Ahmed1, Adel Sehim1
(1) Cairo University, Cairo, Egypt
The Gulf of Suez is a major petroliferous basin in Egypt. Poor seismic
attributes of sequences underlying thick Miocene salts gave importance in
studying the surface structural architecture and rift-sedimentation aiming at
reaching better subsurface image. The Southwestern rift-segment is selected in
this study where numerous hydrocarbon fields exist in vicinity and few works are
published. Detailed field analysis and mapping revealed multi-storied fault
developments in time and space with variable impact on sedimentation.
Two major interbasinal accommodation zones are delineated with extension in
basement rocks of the rift shoulder as Precambrian shear zones and
imbricate-thrust system. The rift border fault
system bounds the rift and is
represented by linked short segments of 4-7 km long. Several
fault
-segments
propagated in one direction showing maximum displacement at one
fault
tip.
Hard-linkage transfer faults connect
fault
tips of variable magnitudes.
Differential evolution of fault
-segments had a great impact on
rift-sedimentation. Entrapment of early-rift sediments adjacent to some faults
indicates early-rift
fault
development whereas divergent sedimentary-wedging
away from other faults refers to deposition on flexure-zone above a blind
fault
.
Deposition of younger sequences adjacent to
fault
planes prove later
fault
-ruptures.
The differential fault
development and along-strike displacement variations
are reflected on the rift shoulder paleoslopes. Channel reservoir clastics
derived from the shoulder into the rift basin across
trap
-door transfer faults.