Opening History and Structural Evolution of the Northern Red Sea Based on Integration of Outcrop, Well and Seismic Data: Implications to Hydrocarbon Exploration

By

 William Bosworth¹, David A. Smith², Kenneth W. Carlson², Janine J. Barnard², Mahmoud F. Raslan²

(1) Marathon International Petroleum, Ltd, London, United Kingdom (2) Marathon Oil Company, Houston, TX

 The opening of the Red Sea occurred in three phases: 1) formation of Early Miocene half-graben linked by accommodation zones, strongly influenced by pre-existing basement fabrics. 22-24 Ma old dikes and fault kinematics indicate that the extension direction was N55E (rift orthogonal). 2) development of a triple junction at the southern end of the Gulf of Suez at 12-14 Ma. The new extension direction was N15E (oblique rifting), parallel to the Gulf of Aqaba transform. Massive halite was deposited throughout most of the basin due to closure of the seaway connection to the Mediterranean. 3) Latest Miocene to Recent formation of an axial bathymetric trough underlain by highly extended and magmatised continental crust. The axial trough is segmented by incipient fracture zones that parallel the Gulf of Aqaba, as at Zabargad Island. Individual segments of the axial trough are slightly oblique to the Miocene rift trend in response to the rotation of the regional extension direction. Salt ridges formed along both margins of the Red Sea, trapping post-salt sediments in rim-synclinal basins. This resulted in a starved axial region, where the salt maintained a sub-horizontal upper surface despite extensive faulting at depth. Large areas of both margins are collapsing into the deeper basin via gravity faults that detach within the Miocene salt. The hydrocarbon systems operating in the northern Red Sea are within the Early Miocene section. Hence, a key to exploration lies in separating the effects of phase one deformation from those of the younger events listed above.