Evolution of a volcanic rifted margin: Southern Red Sea, Ethiopia

Wolfenden, E.; Ebinger, C. J.; Yirgu, Gezahegn; Renne, Paul R.; Kelley, Simon P.

doi:10.1130/b25516.1

Cited by 236 publications

(301 citation statements)

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“…The synrift volcanic geology of the western Afar margin shows that during the period 25-7 Ma, extension and volcanism in the southern Red Sea rift migrated 40-50 km westward of the main border fault; the morphology and spatial extent of lava flows suggest that intrusion and volcanism localised to narrow magmatic segments akin to those that are currently active in the MER Wolfenden et al, 2005) (Fig. 2).…”

Section: Localisation Of Strainmentioning

confidence: 99%

“…The geology of the southern Red Sea margin suggests that by 20-25 Ma, strain had shifted to narrow rift axial zones characterised by basaltic fissural eruptions and faults with metre-scale offsets (Wolfenden et al, 2005) (Fig. 2).…”

Section: Along-rift Variations In the Southern Red Sea Rift Of Afarmentioning

confidence: 99%

“…2). Over time, the locus of extension and magmatism has migrated eastwards overall in the Red Sea rift system Wolfenden et al, 2005), leaving a suite of near surface volcanic rocks that young towards the Quaternary-Recent axial magmatic segments where faulting and magmatism is now localised (e.g., Barberi and Varet, 1977;Manighetti et al, 2001) (Fig. 1).…”

Section: Localisation Of Strainmentioning

confidence: 99%

“…1). Geochronological constraints in Ethiopia suggest rifting began 29-31 Ma on the western Afar margin (e.g., Ayalew et al, 2006;Wolfenden et al, 2005) ( Fig. 3), approximately coeval with~35 Ma faulting along large portions of the Gulf of Aden (Leroy et al, 2010) (Fig.…”

Section: Rift Initiationmentioning

confidence: 99%

“…Simplified structural map of southern Afar and northern Main Ethiopian rift (modified after Keir et al, 2011b). Annotated dates showing the age of the onset of rifting estimated from 40 Ar/ 39 Ar dates on synrift volcanic rocks Ukstins et al, 2002;Wolfenden et al, 2004Wolfenden et al, , 2005. Thin gray lines are Pliocene age faults, and thin black lines are Quaternary-Recent faults along the rift axis.…”

Section: Rift Initiationmentioning

confidence: 99%

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The development of extension and magmatism in the Red Sea rift of Afar

et al. 2013

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Despite the importance of continental breakup in plate tectonics, precisely how extensional processes such as brittle faulting, ductile plate stretching, and magma intrusion evolve in space and time during the development of new ocean basins remains poorly understood. The rifting of Arabia from Africa in the Afar depression is an ideal natural laboratory to address this problem since the region exposes subaerially the tectonically active transition from continental rifting to incipient seafloor spreading. We review recent constraints on along-axis variations in rift morphology, crustal and mantle structure, the distribution and style of ongoing faulting, subsurface magmatism and surface volcanism in the Red Sea rift of Afar to understand processes ultimately responsible for the formation of magmatic rifted continental margins. Our synthesis shows that there is a fundamental change in rift morphology from central Afar northward into the Danakil depression, spatially coincident with marked thinning of the crust, an increase in the volume of young basalt flows, and subsidence of the land towards and below sea-level. The variations can be attributed to a northward increase in proportion of extension by ductile plate stretching at the expense of magma intrusion. This is likely in response to a longer history of localised heating and weakening in a narrower rift. Thus, although magma intrusion accommodates strain for a protracted period during rift development, the final stages of breakup are dominated by a phase of plate stretching with a shift from intrusive to extrusive magmatism. This late-stage pulse of decompression melting due to plate thinning may be responsible for the formation of seaward dipping reflector sequences of basalts and sediments, which are ubiquitous at magmatic rifted margins worldwide.

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Section: Localisation Of Strainmentioning

confidence: 99%

Section: Along-rift Variations In the Southern Red Sea Rift Of Afarmentioning

confidence: 99%

Section: Localisation Of Strainmentioning

confidence: 99%

Section: Rift Initiationmentioning

confidence: 99%

Section: Rift Initiationmentioning

confidence: 99%

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The development of extension and magmatism in the Red Sea rift of Afar

et al. 2013

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Receiver function constraints on crustal seismic velocities and partial melting beneath the Red Sea rift and adjacent regions, Afar Depression

et al. 2014

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The Afar Depression is an ideal locale for the investigation of crustal processes involved in the transition from continental rifting to oceanic spreading. To provide relatively high resolution images of the crust beneath the Red Sea rift (RSR) represented by the Tendaho graben in the Afar Depression, we deployed an array of 18 broadband seismic stations in 2010 and 2011. Stacking of about 2300 receiver functions from the 18 and several nearby stations along the ∼200 km long array reveals an average crustal thickness of 22 ± 4 km, ranging from ∼17 km near the RSR axis to 30 km within the overlap zone between the Red Sea and Gulf of Aden rifts. The resulting anomalously high V p ∕V s ratios decrease from 2.40 in the southwest to 1.85 within the overlap zone. We utilize theoretical V p and melt fraction relationships to obtain an overall highly reduced average crustal V p of ∼5.1 km/s. The melt percentage is about 10% beneath the RSR while the overlap zone contains minor quantities of partial melt. The observed high V p ∕V s values beneath most of the study area indicate widespread partial melting beneath the southwest half of the profile, probably as a result of gradual eastward migration of the RSR axis. Our results also suggest that the current extensional strain in the lower crust beneath the region is diffuse, while the strain field in the upper crust is localized along narrow volcanic segments. These disparate styles of deformation imply a high degree of decoupling between the upper and lower crust.

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The protracted development of focused magmatic intrusion during continental rifting

et al. 2014

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The transition from mechanical thinning toward focused magmatic intrusion during continental rifting is poorly constrained; the tectonically active Main Ethiopian Rift (MER) provides an ideal study locale to address this issue. The presence of linear magmatic-tectonic belts in the relatively immature central MER may indicate that the transition from mechanical to magmatic rifting is more spatially distributed and temporally protracted than has previously been assumed. Here we examine lava geochemistry and vent distribution of a Pliocene-Quaternary linear magmatic chain along the western margin of the central MER-the Akaki Magmatic Zone. Our results show limited variability in parental magma that evolve in a complex polybaric fractionation system that has not changed significantly over the past 3 Ma. Our results suggest the following: (1) channeling of plume material and the localization of shear-or topography-induced porosity modulates melt intrusion into the continental lithosphere. (2) Pre-existing lithospheric structures may act as catalysts for intrusion of magmas into the lithospheric mantle. (3) The midcrustal to upper crustal strain regime dictates the surface orientation of volcanic vents. Therefore, although linear magmatic belts like those in the central MER may young progressively toward the rift axis and superficially resemble oceanic style magmatism, they actually represent prebreakup magmatism on continental crust. The oldest linear magmatic belts observed seismically and magnetically at the edge of the ocean basins thus may not, as is often assumed, actually mark the onset of seafloor spreading.

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Evolution of a volcanic rifted margin: Southern Red Sea, Ethiopia

Cited by 236 publications

References 49 publications

The development of extension and magmatism in the Red Sea rift of Afar

The development of extension and magmatism in the Red Sea rift of Afar

Receiver function constraints on crustal seismic velocities and partial melting beneath the Red Sea rift and adjacent regions, Afar Depression

The protracted development of focused magmatic intrusion during continental rifting

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