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Crustal structure of the rifted volcanic margins and uplifted plateau of Western Yemen from receiver function analysis

Crustal structure of the rifted volcanic margins and uplifted plateau of Western Yemen from receiver function analysis
Crustal structure of the rifted volcanic margins and uplifted plateau of Western Yemen from receiver function analysis
We analyse P-wave receiver functions across the western Gulf of Aden and southern Red Sea continental margins in Western Yemen to constrain crustal thickness, internal crustal structure and the bulk seismic velocity characteristics in order to address the role of magmatism, faulting and mechanical crustal thinning during continental breakup. We analyse teleseismic data from 21 stations forming the temporary Young Conjugate Margins Laboratory (YOCMAL) network together with GFZ and Yemeni permanent stations. Analysis of computed receiver functions shows that (1) the thickness of unextended crust on the Yemen plateau is ?35?km; (2) this thins to ?22?km in coastal areas and reaches less than 14?km on the Red Sea coast, where presence of a high-velocity lower crust is evident. The average Vp/Vs ratio for the western Yemen Plateau is 1.79, increasing to ?1.92 near the Red Sea coast and decreasing to 1.68 for those stations located on or near the granitic rocks.

Thinning of the crust, and by inference extension, occurs over a ?130-km-wide transition zone from the Red Sea and Gulf of Aden coasts to the edges of the Yemen plateau. Thinning of continental crust is particularly localized in a <30-km-wide zone near the coastline, spatially co-incident with addition of magmatic underplate to the lower crust, above which on the surface we observe the presence of seaward dipping reflectors (SDRs) and thickened Oligo-Miocene syn-rift basaltic flows. Our results strongly suggest the presence of high-velocity mafic intrusions in the lower crust, which are likely either synrift magmatic intrusion into continental lower crust or alternatively depleted upper mantle underplated to the base of the crust during the eruption of the SDRs. Our results also point towards a regional breakup history in which the onset of rifting was synchronous along the western Gulf of Aden and southern Red Sea volcanic margins followed by a second phase of extension along the Red Sea margin.
Broad-band seismometers, Continental margins: divergent, Large igneous provinces, Kinematics of crustal and mantle deformation, Africa
0956-540X
1673-1690
Ahmed, A.
29a81242-835e-4661-bffd-3831f02ee2b6
Tiberi, C.
f70f72f0-9696-4ccc-844e-05a2448eebcf
Leroy, S.
20b13993-6c5e-4b3f-9e21-5d048439ef26
Stuart, G.W.
42655128-f55d-42a7-afd8-7a2fca1c01a3
Keir, D.
5616f81f-bf1b-4678-a167-3160b5647c65
Sholan, J.
3307ab28-39b2-4b53-874e-d816b5905468
Khanbari, K.
3b7e33b9-bb14-49e4-aa0e-e9cfe7c544d1
Al-Ganad, I.
2ebda730-f6ce-4100-891d-06725e079bc7
Basuyau, C.
ddeaa5c6-f1d0-4cdb-8688-b21a130ccb0b
Ahmed, A.
29a81242-835e-4661-bffd-3831f02ee2b6
Tiberi, C.
f70f72f0-9696-4ccc-844e-05a2448eebcf
Leroy, S.
20b13993-6c5e-4b3f-9e21-5d048439ef26
Stuart, G.W.
42655128-f55d-42a7-afd8-7a2fca1c01a3
Keir, D.
5616f81f-bf1b-4678-a167-3160b5647c65
Sholan, J.
3307ab28-39b2-4b53-874e-d816b5905468
Khanbari, K.
3b7e33b9-bb14-49e4-aa0e-e9cfe7c544d1
Al-Ganad, I.
2ebda730-f6ce-4100-891d-06725e079bc7
Basuyau, C.
ddeaa5c6-f1d0-4cdb-8688-b21a130ccb0b

Ahmed, A., Tiberi, C., Leroy, S., Stuart, G.W., Keir, D., Sholan, J., Khanbari, K., Al-Ganad, I. and Basuyau, C. (2013) Crustal structure of the rifted volcanic margins and uplifted plateau of Western Yemen from receiver function analysis. Geophysical Journal International, 193 (3), 1673-1690. (doi:10.1093/gji/ggt072).

Record type: Article

Abstract

We analyse P-wave receiver functions across the western Gulf of Aden and southern Red Sea continental margins in Western Yemen to constrain crustal thickness, internal crustal structure and the bulk seismic velocity characteristics in order to address the role of magmatism, faulting and mechanical crustal thinning during continental breakup. We analyse teleseismic data from 21 stations forming the temporary Young Conjugate Margins Laboratory (YOCMAL) network together with GFZ and Yemeni permanent stations. Analysis of computed receiver functions shows that (1) the thickness of unextended crust on the Yemen plateau is ?35?km; (2) this thins to ?22?km in coastal areas and reaches less than 14?km on the Red Sea coast, where presence of a high-velocity lower crust is evident. The average Vp/Vs ratio for the western Yemen Plateau is 1.79, increasing to ?1.92 near the Red Sea coast and decreasing to 1.68 for those stations located on or near the granitic rocks.

Thinning of the crust, and by inference extension, occurs over a ?130-km-wide transition zone from the Red Sea and Gulf of Aden coasts to the edges of the Yemen plateau. Thinning of continental crust is particularly localized in a <30-km-wide zone near the coastline, spatially co-incident with addition of magmatic underplate to the lower crust, above which on the surface we observe the presence of seaward dipping reflectors (SDRs) and thickened Oligo-Miocene syn-rift basaltic flows. Our results strongly suggest the presence of high-velocity mafic intrusions in the lower crust, which are likely either synrift magmatic intrusion into continental lower crust or alternatively depleted upper mantle underplated to the base of the crust during the eruption of the SDRs. Our results also point towards a regional breakup history in which the onset of rifting was synchronous along the western Gulf of Aden and southern Red Sea volcanic margins followed by a second phase of extension along the Red Sea margin.

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More information

Published date: June 2013
Keywords: Broad-band seismometers, Continental margins: divergent, Large igneous provinces, Kinematics of crustal and mantle deformation, Africa
Organisations: Geology & Geophysics

Identifiers

Local EPrints ID: 353090
URI: https://eprints.soton.ac.uk/id/eprint/353090
ISSN: 0956-540X
PURE UUID: ca4e213b-ba7a-45bb-815c-47ff23135981
ORCID for D. Keir: ORCID iD orcid.org/0000-0001-8787-8446

Catalogue record

Date deposited: 28 May 2013 08:20
Last modified: 20 Jul 2019 00:44

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