Quantitative analysis of faulting in the Danakil Depression rift of Afar: the importance of faulting in the final stages of magma-rich rifting
Quantitative analysis of faulting in the Danakil Depression rift of Afar: the importance of faulting in the final stages of magma-rich rifting
Magmatic intrusion and faulting both accommodate crustal extension in magma-rich rifts. However, quantitative constraints on the contribution of faulting to total extension and along-rift variations of faulting during the final stages of break-up are lacking. We targeted the Danakil Depression (Afar, Ethiopia) to conduct a quantitative, high-resolution study of fault activity and interaction in a magma-rich rift near break-up. Quantitative analysis of >500 rift axis faults, identified using remote sensing data (satellite imagery, DEMs), shows an increase in fault density, length and connectivity away from magmatic segments. Kinematic and earthquake focal mechanism data demonstrate a transition from transtensional opening in the northern and central sub-regions of the rift to oblique opening in the southern Giulietti Plain and Tat-Ali sub-regions. Oblique opening is attributed to the along-axis step between the Erta-Ale and Harak sub-regions. Integration of seismic reflection and borehole data with the mapped faults shows that extension is primarily accommodated by magmatism within the rift center, with faulting more significant toward the ends of the rift. ∼30% of crustal extension is accommodated by axial faulting in areas of low magmatism, highlighting the importance of faulting even in the final stages of magma-rich rifting. Comparing our findings with spreading ridge morphology and structure, relevant due to the rift maturity and extensive magmatism, we conclude that the Danakil Depression is in a transitional stage between continental rifting and seafloor spreading. Spatial changes in the importance of faulting and magmatism in accommodating extension, alongside rift morphology, resemble the relationships observed along spreading ridges.
East African rift system, extensional faulting, magma-rich continental rifting, remote sensing
Hurman, Gareth L.
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Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Bull, Jonathan M.
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Mcneill, Lisa C.
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Booth, Adam D.
5788b24a-862c-4497-9bd8-bffcceba92c3
Bastow, Ian D.
7a2698d0-d535-4462-a9a9-0e3293d2d667
June 2023
Hurman, Gareth L.
12774b16-c9cc-4d5c-abb1-4dc4d802925a
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Bull, Jonathan M.
974037fd-544b-458f-98cc-ce8eca89e3c8
Mcneill, Lisa C.
1fe6a1e0-ca1a-4b6f-8469-309d0f9de0cf
Booth, Adam D.
5788b24a-862c-4497-9bd8-bffcceba92c3
Bastow, Ian D.
7a2698d0-d535-4462-a9a9-0e3293d2d667
Hurman, Gareth L., Keir, Derek, Bull, Jonathan M., Mcneill, Lisa C., Booth, Adam D. and Bastow, Ian D.
(2023)
Quantitative analysis of faulting in the Danakil Depression rift of Afar: the importance of faulting in the final stages of magma-rich rifting.
Tectonics, 42 (6), [e2022TC007607].
(doi:10.1029/2022TC007607).
Abstract
Magmatic intrusion and faulting both accommodate crustal extension in magma-rich rifts. However, quantitative constraints on the contribution of faulting to total extension and along-rift variations of faulting during the final stages of break-up are lacking. We targeted the Danakil Depression (Afar, Ethiopia) to conduct a quantitative, high-resolution study of fault activity and interaction in a magma-rich rift near break-up. Quantitative analysis of >500 rift axis faults, identified using remote sensing data (satellite imagery, DEMs), shows an increase in fault density, length and connectivity away from magmatic segments. Kinematic and earthquake focal mechanism data demonstrate a transition from transtensional opening in the northern and central sub-regions of the rift to oblique opening in the southern Giulietti Plain and Tat-Ali sub-regions. Oblique opening is attributed to the along-axis step between the Erta-Ale and Harak sub-regions. Integration of seismic reflection and borehole data with the mapped faults shows that extension is primarily accommodated by magmatism within the rift center, with faulting more significant toward the ends of the rift. ∼30% of crustal extension is accommodated by axial faulting in areas of low magmatism, highlighting the importance of faulting even in the final stages of magma-rich rifting. Comparing our findings with spreading ridge morphology and structure, relevant due to the rift maturity and extensive magmatism, we conclude that the Danakil Depression is in a transitional stage between continental rifting and seafloor spreading. Spatial changes in the importance of faulting and magmatism in accommodating extension, alongside rift morphology, resemble the relationships observed along spreading ridges.
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Tectonics - 2023 - Hurman - Quantitative Analysis of Faulting in the Danakil Depression Rift of Afar The Importance of
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Accepted/In Press date: 16 May 2023
e-pub ahead of print date: 26 May 2023
Published date: June 2023
Additional Information:
Funding Information:
GH acknowledges support from PhD studentship funded by the Natural Environmental Research Council (Grant NE/S007210/1). DK was supported by NERC Grant NE/L002531/1 and Italian MIUR PRIN project 2017P9AT72. We thank Quality Seismic Consultancy Limited for provision of the seismic reflection and borehole data.
Publisher Copyright:
© Wiley Periodicals LLC. The Authors.
Keywords:
East African rift system, extensional faulting, magma-rich continental rifting, remote sensing
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Local EPrints ID: 477965
URI: http://eprints.soton.ac.uk/id/eprint/477965
ISSN: 0278-7407
PURE UUID: c4120842-c165-424c-b508-c04b9044fdc1
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Date deposited: 19 Jun 2023 16:30
Last modified: 20 Nov 2024 02:58
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Author:
Adam D. Booth
Author:
Ian D. Bastow
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