The timing of uplift, volcanism, and rifting peripheral to the Red Sea: A case for passive rifting?

Abstract

Prior to the formation of the Red Sea the northeastern Afro/Arabian continent had low relief and was largely below sea level from the Late Cretaceous to the early Oligocene. The events leading to the formation of the Red Sea followed the sequence (1) alkaline volcanism and rifting beginning about 30–32 Ma affecting a narrow linear zone in the continent, (2) rotational block faulting and detachment faulting, well underway by 25 Ma, (3) gabbro and diorite magmatism, andesite to rhyolite volcanism, and fine‐grained nonmarine sedimentation in the rift between 20 and 25 Ma, (4) fine‐grained marine sedimentation in the rift as the early shelves started to subside in the middle Miocene, and (5) uplift of the adjacent continents (about 3 km) and subsidence of the shelves (about 4 km) between 13.8 and 5 Ma. The youth of the uplift is suggested by 44 fission track dates on apatites from rocks of the Proterozoic Arabian Shield that range in age from 13.8 to 568 Ma. The youngest of these ages, coupled with the present high relief along the Arabian escarpment and published heat flow measurements, indicate that 2.5–4 km uplift has occurred in the last 13.8 m.y. The sequence volcanism/rifting followed by uplift leads to our adoption of a passive mantle model for rift origin. Models that require uplift to create the rift are rejected, because of the late uplift. We advocate a model of lithospheric extension caused by two‐dimensional plate stress over those requiring tractional drag at the base of the lithosphere caused by vigorous flow in the asthenosphere. It is acknowledged that traction models could explain the observed data, but they imply a rigid, static lithosphere and seem to require a link between the direction of flow in the asthenosphere and plate motions. Neither requirement is necessary in the extension model. The rift starts with mechanical extension in a narrow zone of lithosphere between 25–32 Ma in our model. The thinned lithosphere is replaced by upwelling asthenosphere and by rocks from the adjacent deep continental lithosphere which flow into the rift. Ductile flow of the deep continental lithosphere is accelerated by partial melting as rocks flow upward toward the rift axis. Once partially melted, rocks formerly part of the continental lithosphere join the upwelling asthenosphere, resulting in a rapid erosion of the lithospheric mantle beneath the continent near the rift edge. The resulting density decrease explains the uplift. We think that the Red Sea began as a consequence of changing plate geometries resulting from the collision of India and Eurasia. After the collision, the segment of the Owens fracture zone north of the Carlsberg Ridge became locked, forcing the northeast corner of Afro/Arabia to rotate with the Indian plate away from the rest of Africa.

Unraveling rift margin evolution and escarpment development ages along the Dead Sea fault using cosmogenic burial ages

“…Uplifted rift 597 shoulders are recognized in rifts of various ages (e.g. Bloom, 1998;Hutchinson et al, 1992; 598 Bohannon et al, 1989). Furthermore, the memory of uplifted rift margins from a time of 599 significant tectonic activity still persists along most continental passive margins (van der Beek 600 and Braun, 1999; Gilchrist and Summerfield, 1994;Beaumont et al, 2000).…”

Numerical modeling of the development of southeastern Red Sea continental margin

“…In fact, the migration and flow of hydrocarbon are genetically related to and controlled by the tectonic stress, rock fabrics, and process of faulting (Finkbeiner et al, 2001). Geomorphological and structural observations from recent Quaternary faults of Wajid sandstone (Figure 15), Farasan islands, and Wadis areas as well as raised coral terraces suggest several active faults and uplifting blocks diverted major rivers and produced highlands along the RSCM (Merghelani and Gallanthine, 1980;Barazangi, 1981;Bohannon, 1986;Bohannon et al, 1989). Surface expressions of faults and folding over the sedimentary sequences are the good indicators of multiphase evolution of the margin.…”

“…Oligocene continental rifting began with extension, subsidence, normal faulting and sedimentation associated with episodic and segmented movement of Arabian peninsula away from Africa. Magmatic expansion resulted in igneous emplacements, and isostatic rebound caused the rift to undergo uplift and local erosion into the rapidly subsiding and tilting basins (Pallister, 1987;Bohannon et al, 1989;Kaliwoda et al, 2007). At depth, RSCM is underlain by a thick Cenozoic sedimentary wedge over oceanic-continental transitional zone.…”

“…Based on the present day (0 Ma) two-dimensional vertical seismic section adopted from Mooney et al (1985) (Figure 3) and using the models of Bohannon (1986), Bohannon et al (1989), Bohannon and Eittrein (1991) and Makris and Rhim (1991), simplified model geometry for the first time of extension for 28 Ma (EM1) and for the uplift time 18 Ma (EM2) were constructed ( Figure 4). Five brittle rock layers were identified from the seismic section for EM3.…”

“…High thermal gradients along the margin form an area for good hydrocarbon potential. RSCM is characterized by occurrences of thin sediments with significant onshore uplift and tectonic subsidence as well as the zone of high seismicity and active faults related to extending lithosphere (Bohannon, 1986;Giraud et al, 1986;Hempton, 1987;Pallister, 1987;Voggenreiter et al, 1988;Bohannon et al, 1989;Davison et al, 1994;Johnson, 1998;Hayashi, 2006, 2007). Several generations of active faults, block faulting and listric normal faults created by the volcanic eruptions strongly suggests regional uplift and tilting (Pallister, 1987;Davison et al, 1994;Kaliwoda et al, 2007).…”