Preferential rifting of continents: A source of displaced terranes

Vink, Gregory E. van der; Morgan, W. Jason; Zhao, Wenquan

doi:10.1029/jb089ib12p10072

Cited by 201 publications

(79 citation statements)

References 15 publications

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“…The rheology of the lithosphere beneath the Afar Depression is weakened by one or more mantle plumes (Ebinger and Sleep, 1998;White and McKenzie, 1989) though the origin and present day location of the plume remains controversial. This propagation of the Red Sea and Gulf of Aden rifts into Afar is in good agreement with the hypothesis that rifting occurring close to the boundary between continental and oceanic crust preferentially forms on continental crust because of its rheological weakness (Vink et al, 1984;Mü ller et al, 2001).…”

Section: Introductionsupporting

confidence: 71%

The August 2002 earthquake sequence in north Afar: Insights into the neotectonics of the Danakil microplate

Ayele

Stuart

Bastow

et al. 2007

Journal of African Earth Sciences

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In August 2002, there was high seismic activity in Afar concentrated at the plateau margin of the northern Ethiopian rift east of Mekele, near the western part of the Danakil microplate. The spatial and temporal distributions of this seismic activity over four weeks indicate the NNW propagation of the Gulf of Aden rift across the Afar Depression towards the western Ethiopian plateau. Fault plane solutions for six larger earthquakes from the August 2002 sequence are estimated from moment tensor inversion of local broadband waveform data. The results show only normal faulting on NNW trending and NE dipping faults, which agree with tectonics of the area and distribution of aftershocks. No strike-slip component is observed in any of our fault plane solutions or those of other workers including Harvard CMT solutions in the region. Such motion would be indicative of oblique-slip deformation between the Nubian plate and the Danakil microplate consistent with counter-clockwise rotation of the microplate. Hypocentral depths of well-constrained events are 5-7 km, which is the approximate elastic plate thickness in the Main Ethiopian rift, possibly indicating the depth to the brittle-ductile transition zone in this part of the Afar Depression. The shallowness of the depth estimates agree with the macroseismic reports available from a wide area in northern Ethiopia. Potential future shallow crustal deformation may cause significant loss of human life and damage to property in the densely populated highland region around Mekele unless measures are taken in improving building standards. The b-value for this sequence is estimated to be 0.66 using a least squares fit, while it is 0.67 ± 0.16 from a maximum-likelihood approach. This estimated b-value is low or the frequency of occurrence of relatively larger magnitude events is high indicating that it is a highly stressed region as evidenced by the recent increase of the seismicity in the area.

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Section: Introductionsupporting

confidence: 71%

The August 2002 earthquake sequence in north Afar: Insights into the neotectonics of the Danakil microplate

Ayele

Stuart

Bastow

et al. 2007

Journal of African Earth Sciences

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“…Jackson 2002), where the mantle is the strongest part of the lithosphere. In contrast, oceanic lithosphere is stronger because it lacks a thick quartz-rich crust, which can explain why rifting is more common in the continental lithosphere (Vink et al 1984). This model is not universally accepted and arguments have been made that the strength of the lithosphere is controlled by a single seismogenic crustal layer (Maggi et al 2000;Jackson 2002).…”

Section: Strength Of the Continental Lithospherementioning

confidence: 98%

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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“…If proven to be a continental fragment, it would provide unique global information on the relative strength of continental and oceanic lithosphere. The olivine rheology of the oceanic lithosphere is estimated to be three times stronger than typical continental lithosphere [34]. Juxtaposed oceanic and continental lithosphere in a tensional stress field would be weakest landward of the continental shelf edge [35] and the Lomonosov Ridge may have formed as a result of this mechanism.…”

Section: Objectivesmentioning

confidence: 99%

Expanding the Cenozoic paleoceanographic record in the Central Arctic Ocean: IODP Expedition 302 Synthesis

Backman

Moran

2009

Open Geosciences

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Abstract:The Arctic Coring Expedition (ACEX) proved to be one of the most transformational missions in almost 40 year of scientific ocean drilling. ACEX recovered the first Cenozoic sedimentary sequence from the Arctic Ocean and extended earlier piston core records from ∼1.5 Ma back to ∼56 Ma. The results have had a major impact in paleoceanography even though the recovered sediments represents only 29% of Cenozoic time. The missing time intervals were primarily the result of two unexpected hiatuses. This important Cenozoic paleoceanographic record was reconstructed from a total of 339 m sediments. The wide range of analyses conducted on the recovered material, along with studies that integrated regional tectonics and geophysical data, produced surprising results including high Arctic Ocean surface water temperatures and a hydrologically active climate during the Paleocene Eocene Thermal Maximum (PETM), the occurrence of a fresher water Arctic in the Eocene, ice-rafted debris as old as middle Eocene, a middle Eocene environment rife with organic carbon, and ventilation of the Arctic Ocean to the North Atlantic through the Fram Strait near the early-middle Miocene boundary. Taken together, these results have transformed our view of the Cenozoic Arctic Ocean and its role in the Earth climate system.

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Preferential rifting of continents: A source of displaced terranes

Cited by 201 publications

References 15 publications

The August 2002 earthquake sequence in north Afar: Insights into the neotectonics of the Danakil microplate

The August 2002 earthquake sequence in north Afar: Insights into the neotectonics of the Danakil microplate

Why is Africa rifting?

Expanding the Cenozoic paleoceanographic record in the Central Arctic Ocean: IODP Expedition 302 Synthesis

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