The East African Rift and Gulf of Suez Rift are examples of continental rift systems in Africa. The East African Rift involves the separation of the Nubian and Somalian tectonic plates, while the Gulf of Suez Rift is part of the Red Sea Rift system. In the Gulf of Suez, extension has generated normal faults that form half-grabens, and stratigraphy can be divided into pre-rift, syn-rift, and post-rift sequences based on the timing of deposition relative to rifting events. The syn-rift strata show evidence of growth faulting and soft sediment deformation during the active phase of rifting.

1. East African Rift
BY: MOHAMMED ELSAYED

2.  East African
Rift
• Is one of the geologic wonders of the world.
• The Nubian Plate makes up most of Africa, while the
smaller plate that is pulling away has been named the
Somalian Plate.
• These two plates are moving away form each other and
also away from the Arabian plate to the north.
• The point where these three plates meet in the Afar
region of Ethiopia forms what is called a triple-junction

4.  The Gulf of
Suez rift
• The Red Sea occupies part of a large rift valley in the
continental crust of Africa and Arabia.
• This break in the crust is part of a complex rift system
that includes the East African Rift System.
• To the north, the Red Sea bifurcates into the Gulfs of
Suez and Aqaba, with the Sinai Peninsula in between.
• The Gulf of Suez rift is a Neogene continental rift .
• In the Red Sea, the amount of extension decreases
northwards into the Gulf of Suez.

5. • This extension was compensated by collapse of large tilted blocks along major NW-oriented
(Clysmic) fault system.
• The structure of the Gulf of Suez region is governed by extensional normal faults that strike
northwest, forming a complex array of tilted half grabens and asymmetric horsts of which
the crests represent a major hydrocarbon exploration target.
• The faults can be divided into two major sets based on trend.
The first set is longitudinally parallel to the axis of the rift created in an extensional
regime during the Neogene.
The second consists of transverse faults with dominant N–S to NE–SW trends.
• Two major accommodation zones separate these three province and extend in NE
directions.
• These are the Zaafarana transfer zone in the north and the Morgan transfer zone in the
south.

8. Tectono sedimentary models of rift
basins:
the Gulf of Suez and the Northern
Red Sea

9. • The geometry of the rift is shown that the pure shear model is applicable
for these areas.

10. Classification of rift basin stratigraphy

11. The lithostratigraphic units in the Gulf of Suez can be subdivided into three
megasequences:
• prerift succession (pre-Miocene or Paleozoic–Eocene),
• synrift succession (Oligocene–Miocene), and
• postrift succession (post-Miocene or Pliocene–Holocene).

12.  Stratigraphic Response to different Geotectonic Rift- Basin
Models
 Pre-rift strata
• Strata deposited prior to rifting according to the paleo-environment .
• The upper surface of the pre-rift strata is the syn-rift unconformity or a superimposed post-rift
unconformity according to the geotectonic evolution of the basin.
• The pre-rift sedimentary cover is unconformably overlaying the Precambrian basement.
• Pre-rift cover varies from about 2000 m in the northern Gulf of Suez to 400- 800 m in the south.

13. Syn-rift unconformity (SRU)
• The unconformity between pre-rift and syn-rift strata.
• The syn-rift unconformity is generated prior to and during rifting and so
underlies syn-rift strata.

15. Syn-rift strata
• Sediments deposited in the active fault-controlled depocentres of the evolving rift.
• The strata can show growth into the active fault.
• Show a syn-depositional fault movement.
• These movements generate soft sediment deformation structures and seismites are
earthquake-deformed layers .
• The term has also applied to soft sediment deformation structures including sand volcano,
sand blows, and clastic dikes.

16. Post-rift unconformity (PRU)
• Erosional surface that marks the base of strata deposited during thermal or
post-rift subsidence phase of a basin.

17. Post-rift strata
• Strata deposited during post-rift subsidence.
• These sediments gradually bury any remaining rift-related topography of the basin and fill
the cooling controlled expanding accommodation space.
• Increase in density of lithosphere and astenosphere, load of sediment and water all have a
large effect on the postrift subsidence rate i.e. occurs spatially wider than the subsidence
induced by mechanical extension.
• Quaternary sediments represent the main post-rift exposures in the Suez rift.

18. Thankyou