Abstract
This paper presents a robust kinematic model that describes northern Red Sea and Gulf of Suez rifting and the development of marginal extensional half-graben sub-basins (ESB). A combination of Landsat Enhanced Thematic Mapper Plus (ETM+) and structural data was used to provide model constraints on the development of rift segments and ESB in the active rift zones. Structural analysis shows rotation and change in strike of rift-bounding faults. The model describes the northern Red Sea region as a poly-phase rift system initiated by late Oligocene (30 - 24 Ma) orthogonal rifting and the development of marginal ESB (now inland ESB), followed by oblique rifting and flank uplift during the early Miocene (24 - 18 Ma). The oblique rifting fragmented the rift depression into segments separated by oblique-slip accommodation within reactivated Pan-African (ca. 600 Ma) fracture zones, resulting in the development of antithetic faults and an en-echelon distribution of inland ESB. The current phase of rifting was instigated by the development of the Dead Sea Transform in response to increased northeasterly extension during the middle Miocene (ca. 18 Ma). The model explains the widening of the Red Sea rift during the last phase more than the Gulf of Suez rift by developing more antithetic faults and formation of offshore ESB, and deepening the rift depression.
Highlights
It is generally accepted that the Red Sea Rift was initiated during the late Oligocene and early Miocene about 30 Ma [1,2]
[6] Makris and Rhim suggested the Red Sea was formed by left lateral strike-slip motion along pre-existing zones of crustal weakness in late Oligocene-early Miocene times that produced pull-apart basins off Egypt and the Sudan, followed by seafloor spreading in the central part of the Red Sea and subsequently propagating to the south [6]
Our interpretation is based on several key observations: 1) Zaafarana accommodation is represented by the intersection between a NE-SW right-oblique fault with downthrow to the north and the bounding fault; 2) it represents the northern end of basement rock exposure on both sides of the Gulf of Suez and juxtaposes pre-rift and syn-rift sediments against the basement rocks; 3) kinematically, right-lateral movement on this NE-SE oblique-slip fault accompanied by the NE-SW extension could account for the development of southwesterly dips in the Suez rift segment, and northeasterly dips in the Gharib rift segment; 4) the coastal extensional sub-basins (ESB) switched their depocenters from east to west; and 5) the dominant fault trend in the Gulf of Suez region is NE-SW (Figures 5 and 6)
Summary
It is generally accepted that the Red Sea Rift was initiated during the late Oligocene and early Miocene about 30 Ma [1,2]. Bohannon et al challenged the diffuse extension model on the grounds that it required unrealistic rates of extension in the lower crust, and suggested a passive rifting model where early rifting resulted from a detachment fault that extended from near the surface on the western rift shoulder to the middle crust beneath the eastern rift shoulder [5]. According to their model, lithospheric mantle beneath the detachment rose and spread by ductile lateral extension, leading to a thinned shallow crust that evolved into a seafloor spreading center.
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