Crustal structure of the Ethiopian Northwestern Plateau and central Afar from receiver function analysis
Crustal structure of the Ethiopian Northwestern Plateau and central Afar from receiver function analysis
In magma-rich continental rifts extension by magma intrusion is thought to accommodate much of the extension. We aim to constrain major melt reservoirs in the crust during magma-rich rifting by applying P-to-S receiver functions (RFs) using legacy teleseismic data having magnitudes Mb > 6.0 and epicentral distances ranging from 30° to 90° and collected between the years 2000 and 2013 in 17 temporary broadband stations in Ethiopia and Eritrea. The majority of the NW Plateau crust shows fast Vs of ∼4–4.7 km/s with localized slow Vs (3.2 km/s) and high Vp/Vs (1.85–2.0) in the mid-crust (∼10–25 km depth). The seismic velocity beneath the Afar crust is fairly homogeneous except beneath the current locus of strain at the magmatic segments, which have a relatively fast Vs. (∼4.5 km/s) at a shallow (∼6–14 km) depth underlain by slower Vs. (<3.2 km/s) and high Vp/Vs (2.0) at lower crustal depths (∼20–25 km). The Moho is sharp beneath most of the plateau stations and more gradational beneath Afar with estimated values of 36–44 km in the NW plateau and 26–30 km in Afar. The results point towards the presence of partial melt in localized places in the mid-crust beneath the NW plateau, and in the lower crust beneath the west of Afar, and particularly focused in the lower crust beneath the magmatic segments in Afar. The results suggest that the lower crust is an important melt reservoir for rift-related magmatic processes. The presence of melt in the NW plateau crust is more difficult to explain but is potentially linked to the broad extension of the plateau, or lateral migration of melt from the rift.
AFAR, Northwest Plateau, crustal structure, gradational moho, partial melt, receiver function
Kibret, Birhanu A.
353b131c-0ca4-4063-9c62-60a407d0c862
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
15 May 2023
Kibret, Birhanu A.
353b131c-0ca4-4063-9c62-60a407d0c862
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Kibret, Birhanu A., Ayele, Atalay and Keir, Derek
(2023)
Crustal structure of the Ethiopian Northwestern Plateau and central Afar from receiver function analysis.
Frontiers in Earth Science, 11, [1170907].
(doi:10.3389/feart.2023.1170907).
Abstract
In magma-rich continental rifts extension by magma intrusion is thought to accommodate much of the extension. We aim to constrain major melt reservoirs in the crust during magma-rich rifting by applying P-to-S receiver functions (RFs) using legacy teleseismic data having magnitudes Mb > 6.0 and epicentral distances ranging from 30° to 90° and collected between the years 2000 and 2013 in 17 temporary broadband stations in Ethiopia and Eritrea. The majority of the NW Plateau crust shows fast Vs of ∼4–4.7 km/s with localized slow Vs (3.2 km/s) and high Vp/Vs (1.85–2.0) in the mid-crust (∼10–25 km depth). The seismic velocity beneath the Afar crust is fairly homogeneous except beneath the current locus of strain at the magmatic segments, which have a relatively fast Vs. (∼4.5 km/s) at a shallow (∼6–14 km) depth underlain by slower Vs. (<3.2 km/s) and high Vp/Vs (2.0) at lower crustal depths (∼20–25 km). The Moho is sharp beneath most of the plateau stations and more gradational beneath Afar with estimated values of 36–44 km in the NW plateau and 26–30 km in Afar. The results point towards the presence of partial melt in localized places in the mid-crust beneath the NW plateau, and in the lower crust beneath the west of Afar, and particularly focused in the lower crust beneath the magmatic segments in Afar. The results suggest that the lower crust is an important melt reservoir for rift-related magmatic processes. The presence of melt in the NW plateau crust is more difficult to explain but is potentially linked to the broad extension of the plateau, or lateral migration of melt from the rift.
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feart-11-1170907
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Accepted/In Press date: 2 May 2023
Published date: 15 May 2023
Additional Information:
Funding Information:
We appreciate the IRIS Data Management Center’s assistance (IRIS DMC). Likewise, author would like to express my profound gratitude to Prof. Robert Herrmann for familiarizing the scientific community with his software package “Computer Program for Seismology.” We would also like to thank Zwaan () for archiving the earthquake epicenters in Afar. Finally, we would like to thank Addis Ababa University for giving me the chance to perform this study. The seismic station network in Ethiopia is financially supported by the International Science Program (ISP) of Uppsala University. The authors want to express their sincere appreciation to all the reviewers, editors, and editorial staff for their invaluable contributions and support.
Funding Information:
Addis Ababa University funded the research project. DK’s time on the work was supported by Natural Environment Research Council under NERC Grant NE/L013932/1, and the Ministero dell’Università e della Ricerca (MiUR) through PRIN grant 2017P9AT72.
Publisher Copyright:
Copyright © 2023 Kibret, Ayele and Keir.
Keywords:
AFAR, Northwest Plateau, crustal structure, gradational moho, partial melt, receiver function
Identifiers
Local EPrints ID: 477820
URI: http://eprints.soton.ac.uk/id/eprint/477820
PURE UUID: 937a903c-d62e-472a-8d23-9e7b90add9d0
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Date deposited: 15 Jun 2023 16:45
Last modified: 06 Jun 2024 01:49
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Author:
Birhanu A. Kibret
Author:
Atalay Ayele
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