Mantle flow, dynamic topography, and rift-flank uplift of Arabia

Daradich, A.; Mitrovica, J. X.; Pysklywec, R. N.; Willett, Sean D.; Forte, A. M.

doi:10.1130/g19661.1

Cited by 133 publications

(102 citation statements)

References 25 publications

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“…4 and 5). These global-scale models have subsequently been used in geodynamic models that successfully predict the amplitude and wavelength of plateau uplift in the region (e.g., Daradich et al, 2003;Forte et al, 2010;Moucha and Forte, 2011), consistent with evidence from U-Th/He thermochronometry data that indicate broad-scale plateau uplift began in the interval 20-30 Ma (Pik et al, 2003).…”

Section: Evidence From Broadband Seismologymentioning

confidence: 97%

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: Evidence From Broadband Seismologymentioning

confidence: 97%

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

et al. 2013

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“…Surface waves as well as regional waveform modeling indicate that on average the Arabian shield crust is 40 -45 km thick, slightly thicker than the average crust for most shields on earth [22][23][24]. Also, slower-than-average P and S velocities were found in the uppermost mantle beneath the western part of the shield [25,26], indicating the upper mantle is anomalously hot and is possibly associated with the uplift of the Arabian shield [26,27]. The low velocity anomaly was found to extend from the Red Sea eastward into the interior of the shield and to be confined to depths shallower than 410 km [26].…”

Section: Introductionmentioning

confidence: 97%

Crustal structure of the Arabian plate: new constraints from the analysis of teleseismic receiver functions

Aldamegh¹,

Sandvol²,

Barazangi³

2005

Earth and Planetary Science Letters

136

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We also employed a grid search waveform modeling technique to estimate the crustal velocity structure for seven stations. A jackknife re-sampling approach was used to estimate errors in the grid search results for three stations. In addition to our results, we have also included published receiver function results from two temporary networks in the Arabian shield and Oman as well as three permanent GSN stations in the region.The average crustal thickness of the late Proterozoic Arabian shield is 39 km. The crust thins to about 23 km along the Red Sea coast and to about 25 km along the margin of the Gulf of Aqaba. In the northern part of the Arabian platform, the crust varies from 33 -37 km thick.However, the crust is thicker (41 -53 km) in the southeastern part of the platform. There is a dramatic change in crustal thickness between the topographic escarpment of the Arabian shield and the shorelines of the Red Sea. We compared our results in the Arabian shield to nine other Proterozoic and Archean shields that include reasonably well-determined Moho depths, mostly based on receiver functions. The average crustal thickness for all shields is 39 km, while the average for Proterozoic shields is 40 km, and the average for Archean shields is 38 km. We found the crustal thickness of Proterozoic shields to vary between 33 and 44 km, while Archean shields vary between 32 and 47 km. Overall, we do not observe a significant difference between Proterozoic and Archean crustal thickness. 3We observed a dramatic change in crustal thickness along the Red Sea margin that occurs over a very short distance. We projected our results over a cross section extending from the Red Sea ridge to the shield escarpment and contrasted it with a typical Atlantic margin. The transition from oceanic to continental crust of the Red Sea margin occurs over a distance of about 250 km, while the transition along a typical portion of the western Atlantic margin occurs at a distance of about 450 km. This important new observation highlights the abruptness of the breakup of Arabia. We argue that a preexisting zone of weakness coupled with anomalously hot upper mantle could have initiated and expedited the breakup.

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“…It is difficult to explain this topography by isostatic compensation due to thickness and density variations, given the known crustal and lithospheric structure of Africa. Instead, it is now commonly accepted that mantle flow driven by density anomalies in the mantle acts to dynamically support the excess elevation in Africa (Lithgow-Bertelloni & Silver 1998) and may even explain the uplift of the western margin of the Arabian craton (Daradich et al 2003).…”

Section: Dynamic Topography and The African Super-plumementioning

confidence: 99%

Why is Africa rifting?

Kendall

Lithgow‐Bertelloni

2016

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Continental rifting has a fundamental role in the tectonic behaviour of the Earth, shaping the surface we live on. Although there is not yet a consensus about the dominant mechanism for rifting, there is a general agreement that the stresses required to rift the continental lithosphere are not readily available. Here we use a global finite element model of the lithosphere to calculate the stresses acting on Africa. We consider the stresses induced by mantle flow, crustal structure and topography in two types of models: one in which flow is exclusively driven by the subducting slabs and one in which it is derived from a shear wave tomographic model. The latter predicts much larger stresses and a more realistic dynamic topography. It is therefore clear that the mantle structure beneath Africa plays a key part in providing the radial and horizontal tractions, dynamic topography and gravitational potential energy necessary for rifting. Nevertheless, the total available stress (c. 100 MPa) is much less than that needed to break thick, cold continental lithosphere. Instead, we appeal to a model of magma-assisted rifting along pre-existing weaknesses, where the strain is localized in a narrow axial region and the strength of the plate is reduced significantly. Mounting geological and geophysical observations support such a model. Gold Open Access:This article is published under the terms of the CC-BY 3.0 license.

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Mantle flow, dynamic topography, and rift-flank uplift of Arabia

Cited by 133 publications

References 25 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

Crustal structure of the Arabian plate: new constraints from the analysis of teleseismic receiver functions

Why is Africa rifting?

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