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Imaging slab-transported fluids and their deep dehydration from seismic velocity tomography in the Lesser Antilles subduction zone

Imaging slab-transported fluids and their deep dehydration from seismic velocity tomography in the Lesser Antilles subduction zone
Imaging slab-transported fluids and their deep dehydration from seismic velocity tomography in the Lesser Antilles subduction zone
Volatiles play a pivotal role in subduction zone evolution, yet their pathways remain poorly constrained. Studying the Lesser Antilles subduction zone can yield new constraints, where old oceanic lithosphere formed by slow-spreading subducts slowly. Here we use local earthquakes recorded by the temporary VoiLA (Volatile recycling in the Lesser Antilles) deployment of ocean-bottom seismometers in the fore- and back-arc to characterize the 3-D seismic structure of the north-central Lesser Antilles subduction zone. Along the slab top, mapped based on seismicity, we find low Vp extending to 130–150 km depth, deeper than expected for magmatic oceanic crust. The slab's most prominent, elevated Vp/Vs anomalies are beneath the fore- and back-arc offshore Guadeloupe and Dominica, where two subducted fracture zones lie with the obliquely subducting boundary between Proto-Caribbean and Equatorial Atlantic lithosphere. These structures, therefore, enhance hydration of the oceanic lithosphere as it forms and evolves and the subsequent dehydration of mantle serpentinite when subducted. Above the slab, we image the asthenosphere wedge as a high Vp/Vs and moderate Vp feature, indicating slab-dehydrated fluids rising through the overlying cold boundary layer that might induce melting further to the west. Our results provide new evidence for the impact of spatially-variable oceanic plate formation processes on slab dehydration and mantle wedge volatile transfer that ultimately impact volcanic processes at the surface, such as the relatively high magmatic output observed on the north-central islands in the Lesser Antilles.
Lesser Antilles, fluids, mantle wedge, seismic velocity, slab, subduction
0012-821X
Bie, Lidong
092bb01f-2f9e-4376-8933-fb3b221cd72f
Hicks, Stephen
036d1b3b-bb7a-4a22-b2ce-71618a1723a3
Rietbrock, Andreas
9fbc63af-9a9a-4dfe-a389-83d92b5f4cc2
Goes, Saskia
8da1004a-3f5b-44c9-9889-046c5b6c537e
Collier, Jenny
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Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
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Maunder, Benjamin
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The VoiLA Consortium
Bie, Lidong
092bb01f-2f9e-4376-8933-fb3b221cd72f
Hicks, Stephen
036d1b3b-bb7a-4a22-b2ce-71618a1723a3
Rietbrock, Andreas
9fbc63af-9a9a-4dfe-a389-83d92b5f4cc2
Goes, Saskia
8da1004a-3f5b-44c9-9889-046c5b6c537e
Collier, Jenny
04a0fcc8-caeb-4f08-a967-a19e57d1a5e1
Rychert, Catherine
70cf1e3a-58ea-455a-918a-1d570c5e53c5
Harmon, Nicholas
10d11a16-b8b0-4132-9354-652e72d8e830
Maunder, Benjamin
5e0a81b5-3b82-4183-8d08-682f6d18b96e

The VoiLA Consortium (2022) Imaging slab-transported fluids and their deep dehydration from seismic velocity tomography in the Lesser Antilles subduction zone. Earth and Planetary Science Letters, 586, [117535]. (doi:10.1016/j.epsl.2022.117535).

Record type: Article

Abstract

Volatiles play a pivotal role in subduction zone evolution, yet their pathways remain poorly constrained. Studying the Lesser Antilles subduction zone can yield new constraints, where old oceanic lithosphere formed by slow-spreading subducts slowly. Here we use local earthquakes recorded by the temporary VoiLA (Volatile recycling in the Lesser Antilles) deployment of ocean-bottom seismometers in the fore- and back-arc to characterize the 3-D seismic structure of the north-central Lesser Antilles subduction zone. Along the slab top, mapped based on seismicity, we find low Vp extending to 130–150 km depth, deeper than expected for magmatic oceanic crust. The slab's most prominent, elevated Vp/Vs anomalies are beneath the fore- and back-arc offshore Guadeloupe and Dominica, where two subducted fracture zones lie with the obliquely subducting boundary between Proto-Caribbean and Equatorial Atlantic lithosphere. These structures, therefore, enhance hydration of the oceanic lithosphere as it forms and evolves and the subsequent dehydration of mantle serpentinite when subducted. Above the slab, we image the asthenosphere wedge as a high Vp/Vs and moderate Vp feature, indicating slab-dehydrated fluids rising through the overlying cold boundary layer that might induce melting further to the west. Our results provide new evidence for the impact of spatially-variable oceanic plate formation processes on slab dehydration and mantle wedge volatile transfer that ultimately impact volcanic processes at the surface, such as the relatively high magmatic output observed on the north-central islands in the Lesser Antilles.

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Accepted/In Press date: 6 April 2022
e-pub ahead of print date: 15 April 2022
Published date: 15 May 2022
Additional Information: Funding Information: This work was funded under Natural Environment Research Council (NERC) Grant Number NE/K010611/1. The authors thank the ?German Instrument Pool for Amphibian Seismology,? hosted by the Alfred Wegener Institute Bremerhaven, for providing the ocean-bottom seismometers and temporary island seismometers, and University of California, San Diego (UCSD) (Scripps) for providing additional ocean-bottom seismometers. The authors thank the captain, John Leask, officers, crew, and science party members who sailed on RRS James Cook cruise JC 133 and JC149 (Collier, 2017). Funding Information: This work was funded under Natural Environment Research Council (NERC) Grant Number NE/K010611/1 . The authors thank the “German Instrument Pool for Amphibian Seismology,” hosted by the Alfred Wegener Institute Bremerhaven, for providing the ocean-bottom seismometers and temporary island seismometers, and University of California, San Diego (UCSD) (Scripps) for providing additional ocean-bottom seismometers. The authors thank the captain, John Leask, officers, crew, and science party members who sailed on RRS James Cook cruise JC 133 and JC149 ( Collier, 2017 ). Publisher Copyright: © 2022 The Author(s) Copyright: Copyright 2022 Elsevier B.V., All rights reserved.
Keywords: Lesser Antilles, fluids, mantle wedge, seismic velocity, slab, subduction

Identifiers

Local EPrints ID: 456903
URI: http://eprints.soton.ac.uk/id/eprint/456903
ISSN: 0012-821X
PURE UUID: 9d1f3f4e-602b-4638-a916-20d88bbb8187
ORCID for Stephen Hicks: ORCID iD orcid.org/0000-0002-7476-3284
ORCID for Nicholas Harmon: ORCID iD orcid.org/0000-0002-0731-768X

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Date deposited: 16 May 2022 16:42
Last modified: 09 Nov 2022 02:42

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Contributors

Author: Lidong Bie
Author: Stephen Hicks ORCID iD
Author: Andreas Rietbrock
Author: Saskia Goes
Author: Jenny Collier
Author: Nicholas Harmon ORCID iD
Author: Benjamin Maunder
Corporate Author: The VoiLA Consortium

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