The Northern Red Sea - a model for rifting leading to continental break-up
Authors: McClay Ken , Bosworth Bill , Khalil Samir , Ligi Marco , Stockli Danny 
Published: March 2021

&lt;p&gt;The Gulf of Suez and the Northern Red Sea form the northwestern sector of the Afro-Arabian rift system. &amp;#160;Studies of outstanding outcrops of rift fault systems and syntectonic strata integrated with sub-surface data together with thermo-chronological studies indicate that the Gulf of Suez - Northern Red Sea rift system initiated at around the Oligocene to Miocene transition (24 to 23 Ma). &amp;#160;A regional NW-SE trending Oligocene-Miocene (~23 Ma) alkali basalt dike swarm and basalt flows near Cairo, appears to mark the onset of crustal-scale extension and continental rifting. &amp;#160;These dikes and scarce local flows, are interbedded with the oldest siliciclastic syn-rift strata (Aquitanian Nukhul Fm.), and are associated with the oldest recognized extensional faulting in the Red Sea. &amp;#160;Bedrock thermochronometric results from the Gulf of Suez and both margins of the Red Sea also point to a latest Oligocene onset of major normal faulting and rift flank exhumation and large-magnitude early Miocene extension along the entire length of the Red Sea rift. &amp;#160;The early phase of rifting produced complex, discontinuous fault patterns with very high rates of fault block rotation, distinct sub-basins with alternating regional dip domains separated by well-defined accommodation zones. &amp;#160;Sedimentary facies were laterally and vertically complex and dominated by marginal to shallow marine siliciclastics of the Abu Zenima, Nukhul and Nakheil Formations. &amp;#160;Neotethyan faunas appeared throughout all of the sub-basins at this time. &amp;#160;During the Early Burdigalian (~20 Ma) tectonically-driven subsidence accelerated and was accompanied by a concordant increase in denudation and uplift of the rift shoulders. &amp;#160;The intra-rift fault networks coalesced into through-going structures and extension became progressively more focused along the rift axis. &amp;#160;This reconfiguration resulted in more laterally continuous depositional facies and the moderate-to-deep marine deposits of the Rudeis, Kareem and Ranga Formations.&lt;br&gt;At the early Middle Miocene (~14 Ma) onset of the left-lateral Gulf of Aqaba transform fault system marked dramatic changes in rift kinematics and sedimentary depositional environments. &amp;#160;The Gulf of Suez became isolated from the active northern Red Sea rift, with a switch from orthogonal to oblique rifting and to hyperextension in the northern Red Sea. &amp;#160;The previous open marine seaway was replaced by an extensive evaporitic basin along the entire length of the rift from the central Gulf of Suez to Yemen/Eritrea. &amp;#160;In Egypt these evaporites are ascribed to the Belayim, South Gharib, Zeit and Abu Dabbab Formations. &amp;#160;Evaporite deposition continued to dominate until the end of the Miocene (~5 Ma) when a subaerial unconformity developed across most of the basins. With the onset of seafloor spreading in the southern Red Sea, Indian Ocean marine waters re-entered through the Bab el Mandab in the earliest Pliocene and re-established open marine conditions. &amp;#160;In the northern Red Sea well and seismic data demonstrate that continental crust extends at least several tens of kilometers offshore. &amp;#160;The northern Red Sea is a highly extended non-volcanic rift and true, laterally integrated sea-floor spreading has not yet developed.&lt;/p&gt;