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Widespread hydration of the back arc and the link to variable hydration of the incoming plate in the lesser antilles from rayleigh wave imaging

Widespread hydration of the back arc and the link to variable hydration of the incoming plate in the lesser antilles from rayleigh wave imaging
Widespread hydration of the back arc and the link to variable hydration of the incoming plate in the lesser antilles from rayleigh wave imaging
Subduction zone dynamics are important for a better understanding of natural hazards, plate tectonics, and the evolution of the planet. Despite this, the factors dictating the location and style of volcanism are not well-known. Here we present Rayleigh Wave imaging of the Lesser Antilles subduction zone using the ocean bottom and land seismic data collected as a part of the VoiLA experiment. This region is an important global endmember that represents a slow (<19 mm/yr) convergence rate of old (80–120 Ma), Atlantic lithosphere formed at a slow spreading ridge. We image the fast slab, the fast-overriding plate and the slow mantle wedge across the entire arc. We find slow velocity anomalies (∼4.1 km/s) in the mantle wedge directly beneath the arc with local minima beneath Dominica/Martinique, Montserrat and the Grenadines. We observe that slow velocities in the wedge extend 200 km into the back arc west of Martinique. The slowest mantle wedge velocity anomaly is more muted than several global wedges, likely reflecting the lower temperatures and less partial melt predicted for the Antilles. Subducted fracture zones and plate boundaries are a potential source of hydration, since they are located near the anomalies, although not directly beneath them. To match our observations, geodynamic models with a broadly hydrated mantle wedge are required, which can be achieved via deep hydration of the slab, and fluid release further into the back arc. In addition, 3-D flow and melt migration or ponding are required to explain the shape and location of our anomalies.
Rayleigh wave, Caribbean Plate, tomography, VOILA, Lesser Antilles, subduction
1525-2027
Harmon, Nicholas
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Rychert, Catherine A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Goes, Saskia
8da1004a-3f5b-44c9-9889-046c5b6c537e
Maunder, Benjamin
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Collier, Jenny
04a0fcc8-caeb-4f08-a967-a19e57d1a5e1
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Lynch, Lloyd
2bdb7db0-2d2f-4fea-8806-d55abdde888b
Rietbrock, Andreas
e4656f22-06be-40fe-8f98-7f88c351c434
Group, the VoiLA Working
c3b9d95b-8232-419e-a98a-85800133cf5c
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Rychert, Catherine A.
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Goes, Saskia
8da1004a-3f5b-44c9-9889-046c5b6c537e
Maunder, Benjamin
5e0a81b5-3b82-4183-8d08-682f6d18b96e
Collier, Jenny
04a0fcc8-caeb-4f08-a967-a19e57d1a5e1
Henstock, Timothy
27c450a4-3e6b-41f8-97f9-4e0e181400bb
Lynch, Lloyd
2bdb7db0-2d2f-4fea-8806-d55abdde888b
Rietbrock, Andreas
e4656f22-06be-40fe-8f98-7f88c351c434
Group, the VoiLA Working
c3b9d95b-8232-419e-a98a-85800133cf5c

Harmon, Nicholas, Rychert, Catherine A., Goes, Saskia, Maunder, Benjamin, Collier, Jenny, Henstock, Timothy, Lynch, Lloyd, Rietbrock, Andreas and Group, the VoiLA Working (2021) Widespread hydration of the back arc and the link to variable hydration of the incoming plate in the lesser antilles from rayleigh wave imaging. Geochemistry, Geophysics, Geosystems, 22 (7), [e2021GC009707]. (doi:10.1029/2021GC009707).

Record type: Article

Abstract

Subduction zone dynamics are important for a better understanding of natural hazards, plate tectonics, and the evolution of the planet. Despite this, the factors dictating the location and style of volcanism are not well-known. Here we present Rayleigh Wave imaging of the Lesser Antilles subduction zone using the ocean bottom and land seismic data collected as a part of the VoiLA experiment. This region is an important global endmember that represents a slow (<19 mm/yr) convergence rate of old (80–120 Ma), Atlantic lithosphere formed at a slow spreading ridge. We image the fast slab, the fast-overriding plate and the slow mantle wedge across the entire arc. We find slow velocity anomalies (∼4.1 km/s) in the mantle wedge directly beneath the arc with local minima beneath Dominica/Martinique, Montserrat and the Grenadines. We observe that slow velocities in the wedge extend 200 km into the back arc west of Martinique. The slowest mantle wedge velocity anomaly is more muted than several global wedges, likely reflecting the lower temperatures and less partial melt predicted for the Antilles. Subducted fracture zones and plate boundaries are a potential source of hydration, since they are located near the anomalies, although not directly beneath them. To match our observations, geodynamic models with a broadly hydrated mantle wedge are required, which can be achieved via deep hydration of the slab, and fluid release further into the back arc. In addition, 3-D flow and melt migration or ponding are required to explain the shape and location of our anomalies.

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Published date: 8 June 2021
Additional Information: https://doi.org/10.1029/2021GC009707
Keywords: Rayleigh wave, Caribbean Plate, tomography, VOILA, Lesser Antilles, subduction

Identifiers

Local EPrints ID: 450325
URI: http://eprints.soton.ac.uk/id/eprint/450325
ISSN: 1525-2027
PURE UUID: 5826288c-936e-4b12-b37f-f2f5ce93b67c
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X
ORCID for Timothy Henstock: ORCID iD orcid.org/0000-0002-2132-2514

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Date deposited: 23 Jul 2021 16:30
Last modified: 24 Jul 2021 01:42

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Contributors

Author: Nicholas Harmon ORCID iD
Author: Saskia Goes
Author: Benjamin Maunder
Author: Jenny Collier
Author: Lloyd Lynch
Author: Andreas Rietbrock
Author: the VoiLA Working Group

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