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

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Title: Imaging slab-transported fluids and their deep dehydration from seismic velocity tomography in the Lesser Antilles subduction zone
Authors: Bie, L
Hicks, S
Rietbrock, A
Goes, S
Collier, J
Rychert, C
Harmon, N
Maunder, B
Item Type: Journal 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.
Issue Date: 15-May-2022
Date of Acceptance: 6-Apr-2022
URI: http://hdl.handle.net/10044/1/96657
DOI: 10.1016/j.epsl.2022.117535
ISSN: 0012-821X
Publisher: Elsevier BV
Start Page: 117535
End Page: 117535
Journal / Book Title: Earth and Planetary Science Letters
Volume: 586
Copyright Statement: /© 2022 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/)
Sponsor/Funder: Natural Environment Research Council (NERC)
Funder's Grant Number: NE/K010743/1
Keywords: Geochemistry & Geophysics
02 Physical Sciences
04 Earth Sciences
Publication Status: Published
Article Number: 117535
Appears in Collections:Earth Science and Engineering



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