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Strain accommodation by intrusion and faulting in a rift linkage zone: evidences from high-resolution topography data of the Afrera Plain (Afar, East Africa)

Strain accommodation by intrusion and faulting in a rift linkage zone: evidences from high-resolution topography data of the Afrera Plain (Afar, East Africa)
Strain accommodation by intrusion and faulting in a rift linkage zone: evidences from high-resolution topography data of the Afrera Plain (Afar, East Africa)
At mature magma-rich continental rifts, extension focuses along discrete axial segments where magmatism and diking are important in accommodating plate divergence. However, the role of magma in influencing the deformation at rift–rift offsets is still unclear as direct observations are rare. Here, we exploited high-resolution Pléiades-1 tri-stereo imagery to produce the first 1 m Digital Elevation Model of the Afrera Plain linkage zone between the Erta Ale and Tat Ali magmatic segments in Northern Afar. We carried out a detailed structural analysis of both tectonic and magmatic features in the area and observed different trends and kinematics of these features. Magmatic features at Afrera strike N160°E ± 5°E, similar to the Erta Ale segment and perpendicular to the extension direction. Conversely, tectonic features fall into two families of ∼NW-SE- and ∼NS-striking oblique faults with right-lateral and left-lateral components, respectively, as shown by Riedel shears. We interpret the extension direction of tectonic features using observed opening of fractures, previous seismic, and InSAR-based fault models and from that expected for the mapped conjugate fault pattern. While the results show scatter in the range of N46°E–N68°E, it is similar within error to the regional extension direction. The simplest model that explains our data is that in the linkage zone there is both extensional and shear strain. The dikes accommodate only extension, while conjugate oblique faults accommodate extension and shear strain. Our study shows that both magmatism and faulting are important during rift segment interaction and linkage.
Afar, DEM, Pleiades-1, rift systems, transfer zone
0278-7407
La Rosa, Alessandro
3443c440-23fe-437e-b908-80f6b923c4ba
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Hurman, Gareth L.
12774b16-c9cc-4d5c-abb1-4dc4d802925a
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
La Rosa, Alessandro
3443c440-23fe-437e-b908-80f6b923c4ba
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Hurman, Gareth L.
12774b16-c9cc-4d5c-abb1-4dc4d802925a
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

La Rosa, Alessandro, Pagli, Carolina, Hurman, Gareth L. and Keir, Derek (2022) Strain accommodation by intrusion and faulting in a rift linkage zone: evidences from high-resolution topography data of the Afrera Plain (Afar, East Africa). Tectonics, 41 (6), [e2021TC007115]. (doi:10.1029/2021TC007115).

Record type: Article

Abstract

At mature magma-rich continental rifts, extension focuses along discrete axial segments where magmatism and diking are important in accommodating plate divergence. However, the role of magma in influencing the deformation at rift–rift offsets is still unclear as direct observations are rare. Here, we exploited high-resolution Pléiades-1 tri-stereo imagery to produce the first 1 m Digital Elevation Model of the Afrera Plain linkage zone between the Erta Ale and Tat Ali magmatic segments in Northern Afar. We carried out a detailed structural analysis of both tectonic and magmatic features in the area and observed different trends and kinematics of these features. Magmatic features at Afrera strike N160°E ± 5°E, similar to the Erta Ale segment and perpendicular to the extension direction. Conversely, tectonic features fall into two families of ∼NW-SE- and ∼NS-striking oblique faults with right-lateral and left-lateral components, respectively, as shown by Riedel shears. We interpret the extension direction of tectonic features using observed opening of fractures, previous seismic, and InSAR-based fault models and from that expected for the mapped conjugate fault pattern. While the results show scatter in the range of N46°E–N68°E, it is similar within error to the regional extension direction. The simplest model that explains our data is that in the linkage zone there is both extensional and shear strain. The dikes accommodate only extension, while conjugate oblique faults accommodate extension and shear strain. Our study shows that both magmatism and faulting are important during rift segment interaction and linkage.

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Accepted/In Press date: 18 May 2022
e-pub ahead of print date: 24 May 2022
Published date: June 2022
Keywords: Afar, DEM, Pleiades-1, rift systems, transfer zone

Identifiers

Local EPrints ID: 457954
URI: http://eprints.soton.ac.uk/id/eprint/457954
ISSN: 0278-7407
PURE UUID: bce63545-6c13-4f04-948a-e3b0d5a8dfc4
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

Catalogue record

Date deposited: 23 Jun 2022 17:15
Last modified: 24 Jun 2022 01:43

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Contributors

Author: Alessandro La Rosa
Author: Carolina Pagli
Author: Derek Keir ORCID iD

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