Upper mantle P-wave speed variations beneath Ethiopia and the origin of the Afar hotspot

Benoit, M. H.; Nyblade, A.; VanDecar, J. C.

doi:10.1130/g22281.1

Cited by 116 publications

(135 citation statements)

References 19 publications

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“…[2001] and Benoit et al [2006], as well as several global models [Romanowicz and Gung, 2002;Montelli et al, 2004] show that its origin could be tracked down to at least the transition zone, though its connection with the so-called south African superplume is controversial [Davaille et al, 2005].…”

Section: Surface Wave Tomographic Resultsmentioning

confidence: 99%

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Montagner¹,

Marty²,

Stutzmann³

et al. 2007

Geophysical Research Letters

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International audienceThe relationship between intraplate volcanism and continental tectonics has been investigated for North and East Africa using a high resolution three-dimensional anisotropic tomographic model derived from seismic data of a French experiment “Horn of Africa” and existing broadband data. The joint inversion for seismic velocity and anisotropy of the upper 400 km of the mantle, and geochemical data reveals a complex interaction between mantle upwellings, and lithosphere. Two kinds of mantle upwellings can be distinguished: The first one, the Afar “plume” originates from deeper than 400 km and is characterized by enrichment in primordial 3He and 3He/4He ratios higher than those along mid-ocean ridges (MOR). The second one, associated with other Cenozoic volcanic provinces (Darfur, Tibesti, Hoggar, Cameroon), with 3He/4He ratios similar to, or lower than MOR, is a consequence of shallower upwelling. The presumed asthenospheric convective instabilities are oriented in an east-west direction, resulting from interaction between south-north asthenospheric mantle flow, main plume head and topography on the base of lithosphere

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Section: Surface Wave Tomographic Resultsmentioning

confidence: 99%

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Montagner¹,

Marty²,

Stutzmann³

et al. 2007

Geophysical Research Letters

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“…In the case of Ethiopia, transition zone thickness, determined by receiver function analysis, shows evidence for thinning compared to the global mean; Cornwell et al (2011) cited this as evidence for high temperatures at transition zone depths, and thus connectivity between shallow low velocities imaged tomographically in Ethiopia (e.g., Bastow et al, 2008;Benoit et al, 2006;Debayle et al, 2001;Hansen et al, 2012;Pasyanos and Nyblade, 2007) and the superplume in the lower mantle beneath.…”

Section: Evidence From Broadband Seismologymentioning

confidence: 99%

“…The consensus emerging from recent studies in Ethiopia is that it is underlain by a broad low velocity anomaly, not a traditional narrow mantle plume (e.g., Bastow et al, 2008;Benoit et al, 2006;Cornwell et al, 2011;Hansen et al, 2012;Ritsema et al, 2010) (Fig. 5).…”

Section: Implications For the Thermochemical State Of The Ethiopian Mmentioning

confidence: 99%

“…In recent years, major geoscientific experiments in Ethiopia such as the Ethiopia-Kenya Broadband Seismic Experiment (EKBSE; e.g., Benoit et al, 2006) and the Ethiopia Afar Geoscientific Lithospheric Experiment (EAGLE; e.g., have facilitated increasingly high resolution imaging of the Ethiopian mantle. Seismic tomographic studies on the global-to-regional scale, however, have revealed a broad (~500 km-wide)~3% slow shear wave-speed anomaly that originates at the core-mantle boundary beneath southern Africa and extends toward the base of the lithosphere somewhere beneath Ethiopia (e.g., Grand, 2002;Li et al, 2008;Ritsema and Allen, 2003;Ritsema et al, 2010;Simmons et al, 2007): the African superplume (Figs.…”

Section: Evidence From Broadband Seismologymentioning

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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“…In particular, deep seismic structure beneath different segments of EARS was investigated in various seismic studies. Regional travel-time tomography by Benoit et al (2006) shows presence of a single plume beneath the Ethiopia. Results of SKS-splitting analysis (Hansen et al, 2006) and tomography Park et al (2007Park et al ( , 2008 suggested presence of the channeled mantle flow from the Afar hot spot.…”

Section: East African Rift System: Plumes or Convective Flows?mentioning

confidence: 99%

Multiscale Seismic Tomography Imaging of Volcanic Complexes

Koulakov¹

2012

Updates in Volcanology - A Comprehensive Approach to Volcanological Problems

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Upper mantle P-wave speed variations beneath Ethiopia and the origin of the Afar hotspot

Cited by 116 publications

References 19 publications

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

Mantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa

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

Multiscale Seismic Tomography Imaging of Volcanic Complexes

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