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Evolution of the Alu-Dalafilla and Borale volcanoes, Afar, Ethiopia

Evolution of the Alu-Dalafilla and Borale volcanoes, Afar, Ethiopia
Evolution of the Alu-Dalafilla and Borale volcanoes, Afar, Ethiopia

The Danakil depression marks a progressive change from continental rifting in Afar to seafloor spreading further north in the Red Sea. Extension and volcanism in this incipient spreading centre is localised to the ~70-km-long, 20-km-wide active Erta Ale volcanic segment. Here, we combine remote sensing and major element geochemical analysis to determine the structure and composition of three volcanoes on the Erta Ale Volcanic Segment: the Alu dome, the Dalafilla stratovolcano and the Borale stratovolcano. We investigate the evolution and compositional variation within and between these volcanic complexes. Our results show that most flows are sourced from scoria cones and fissures, representing in total 15 phases of volcanism that occurred within four major eruptive stages, most likely occurring in the last 80 thousand years (kyr). The first stage represents large-scale fissure volcanism, comprising submarine basaltic phases. Stage two involves basaltic fissure volcanism around Alu. The third stage is dominated by trachy-andesite to rhyolitic volcanism from the volcanic edifices of Alu, Dalafilla and Borale and the fourth by a resumption of small-scale basaltic/trachybasalt fissure systems. Geochemical modelling indicates a paucity of crustal assimilation and mixing within the sub-volcanic magmatic system. Spatial analysis of volcanic cones and fissures within the area indicate the presence of a cone sheet and ring faults. The fissures are likely fed by sills connecting the magma source with the volcanic edifices of Alu and Borale. Our results reveal the cyclic nature of both eruption style and composition of major volcanic complexes in rift environments, prior to the onset of seafloor spreading.

Afar, Basaltic volcanism, Fissures, Rifting
0377-0273
Watts, Emma Jade
5385ca5b-e177-402d-b373-7d71637ee1e6
Gernon, Thomas
658041a0-fdd1-4516-85f4-98895a39235e
Taylor, Rex N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Siegburg, Melanie
b4801eca-cd00-401b-8cb0-a21da9754c42
Jarman, Jasmin
6c1f529b-f889-4233-9952-3ef936b9caa3
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Gioncada, Anna
498799a3-7cf3-469a-89cc-6bdf1c7deaac
Watts, Emma Jade
5385ca5b-e177-402d-b373-7d71637ee1e6
Gernon, Thomas
658041a0-fdd1-4516-85f4-98895a39235e
Taylor, Rex N.
094be7fd-ef61-4acd-a795-7daba2bc6183
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Siegburg, Melanie
b4801eca-cd00-401b-8cb0-a21da9754c42
Jarman, Jasmin
6c1f529b-f889-4233-9952-3ef936b9caa3
Pagli, Carolina
290edb22-712b-4563-a868-af4c21fdb6b0
Gioncada, Anna
498799a3-7cf3-469a-89cc-6bdf1c7deaac

Watts, Emma Jade, Gernon, Thomas, Taylor, Rex N., Keir, Derek, Siegburg, Melanie, Jarman, Jasmin, Pagli, Carolina and Gioncada, Anna (2020) Evolution of the Alu-Dalafilla and Borale volcanoes, Afar, Ethiopia. Journal of Volcanology and Geothermal Research, 408, [107094]. (doi:10.1016/j.jvolgeores.2020.107094).

Record type: Article

Abstract

The Danakil depression marks a progressive change from continental rifting in Afar to seafloor spreading further north in the Red Sea. Extension and volcanism in this incipient spreading centre is localised to the ~70-km-long, 20-km-wide active Erta Ale volcanic segment. Here, we combine remote sensing and major element geochemical analysis to determine the structure and composition of three volcanoes on the Erta Ale Volcanic Segment: the Alu dome, the Dalafilla stratovolcano and the Borale stratovolcano. We investigate the evolution and compositional variation within and between these volcanic complexes. Our results show that most flows are sourced from scoria cones and fissures, representing in total 15 phases of volcanism that occurred within four major eruptive stages, most likely occurring in the last 80 thousand years (kyr). The first stage represents large-scale fissure volcanism, comprising submarine basaltic phases. Stage two involves basaltic fissure volcanism around Alu. The third stage is dominated by trachy-andesite to rhyolitic volcanism from the volcanic edifices of Alu, Dalafilla and Borale and the fourth by a resumption of small-scale basaltic/trachybasalt fissure systems. Geochemical modelling indicates a paucity of crustal assimilation and mixing within the sub-volcanic magmatic system. Spatial analysis of volcanic cones and fissures within the area indicate the presence of a cone sheet and ring faults. The fissures are likely fed by sills connecting the magma source with the volcanic edifices of Alu and Borale. Our results reveal the cyclic nature of both eruption style and composition of major volcanic complexes in rift environments, prior to the onset of seafloor spreading.

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Watts 2020 inpress - Accepted Manuscript
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Accepted/In Press date: 14 October 2020
e-pub ahead of print date: 24 October 2020
Published date: 15 December 2020
Additional Information: Funding Information: This research was funded by the Natural Environmental Research Council [grant number NE/L002531/1 ]. T.M.G was supported by a Natural Envrionmental Research Council grant [NE/R004978/1]. We acknowledge the use of rocks from the Afar Repository of the University of Pisa, Italy ( http://repositories.dst.unipi.it/index.php/home-afar ). D.K., C.P., and A.G., are funded by 2017 PRIN project - protocol MIUR : 2017P9AT72 PE10 . C.P. acknowledges support by the University of Pisa grant PRA_2018_19. We thank Laura De Dosso for her help with the Afar Repository samples. Publisher Copyright: © 2020 The Authors
Keywords: Afar, Basaltic volcanism, Fissures, Rifting

Identifiers

Local EPrints ID: 444612
URI: http://eprints.soton.ac.uk/id/eprint/444612
ISSN: 0377-0273
PURE UUID: 7d442f6c-35c4-4ab1-ab6f-710a045e399b
ORCID for Emma Jade Watts: ORCID iD orcid.org/0000-0001-6823-395X
ORCID for Thomas Gernon: ORCID iD orcid.org/0000-0002-7717-2092
ORCID for Rex N. Taylor: ORCID iD orcid.org/0000-0002-9367-0294
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 27 Oct 2020 19:55
Last modified: 27 Oct 2022 04:01

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Contributors

Author: Emma Jade Watts ORCID iD
Author: Thomas Gernon ORCID iD
Author: Rex N. Taylor ORCID iD
Author: Derek Keir ORCID iD
Author: Melanie Siegburg
Author: Jasmin Jarman
Author: Carolina Pagli
Author: Anna Gioncada

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