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The protracted development of the continent–ocean transition in Afar

The protracted development of the continent–ocean transition in Afar
The protracted development of the continent–ocean transition in Afar
Continental breakup and the transition to seafloor spreading is characterized by extensional faulting, thinning of the lithosphere and, at magmatic margins, voluminous intrusive and extrusive magmatism1, 2, 3, 4. It is difficult to discriminate between different mechanisms of extension and magmatism at ancient continental margins because the continent–ocean transition is buried beneath thick layers of volcanic and sedimentary rocks5, 6 and the tectonic activity that characterized breakup has ceased. Instead, the timing of these mechanisms is inferred from theoretical models or from the geological record preserved at the fully developed, ancient rifted margins1, 5, 7, 8. Ongoing rifting in Ethiopia offers a unique opportunity to address these problems because it exposes subaerially the transition between continental rifting towards the south and seafloor spreading further northward. Here we synthesize constraints on the spatial and temporal evolution of magmatism and extension in Ethiopia. We show that although intrusion of magma maintains crustal thickness during the early stages of the continent–ocean transition, subsidence of the margin below sea level, and eruption of voluminous basalt flows, is initiated by late-stage thinning of the heavily intruded, weakened plate just before the onset of seafloor spreading. We thus conclude that faulting, stretching and magma intrusion are each important, but at different times during breakup.
1752-0894
248-250
Bastow, Ian D.
7a2698d0-d535-4462-a9a9-0e3293d2d667
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Bastow, Ian D.
7a2698d0-d535-4462-a9a9-0e3293d2d667
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

Bastow, Ian D. and Keir, Derek (2011) The protracted development of the continent–ocean transition in Afar. Nature Geoscience, 4 (4), 248-250. (doi:10.1038/ngeo1095).

Record type: Article

Abstract

Continental breakup and the transition to seafloor spreading is characterized by extensional faulting, thinning of the lithosphere and, at magmatic margins, voluminous intrusive and extrusive magmatism1, 2, 3, 4. It is difficult to discriminate between different mechanisms of extension and magmatism at ancient continental margins because the continent–ocean transition is buried beneath thick layers of volcanic and sedimentary rocks5, 6 and the tectonic activity that characterized breakup has ceased. Instead, the timing of these mechanisms is inferred from theoretical models or from the geological record preserved at the fully developed, ancient rifted margins1, 5, 7, 8. Ongoing rifting in Ethiopia offers a unique opportunity to address these problems because it exposes subaerially the transition between continental rifting towards the south and seafloor spreading further northward. Here we synthesize constraints on the spatial and temporal evolution of magmatism and extension in Ethiopia. We show that although intrusion of magma maintains crustal thickness during the early stages of the continent–ocean transition, subsidence of the margin below sea level, and eruption of voluminous basalt flows, is initiated by late-stage thinning of the heavily intruded, weakened plate just before the onset of seafloor spreading. We thus conclude that faulting, stretching and magma intrusion are each important, but at different times during breakup.

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Published date: March 2011
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 180899
URI: https://eprints.soton.ac.uk/id/eprint/180899
ISSN: 1752-0894
PURE UUID: 0c4035bc-c906-4907-9c68-c4382086e13d
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 12 Apr 2011 10:46
Last modified: 06 Jun 2018 12:31

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Contributors

Author: Ian D. Bastow
Author: Derek Keir ORCID iD

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