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

Bie, Lidong, Hicks, Stephen, Rietbrock, Andreas, Goes, Saskia, Collier, Jenny, Rychert, Catherine, Harmon, Nicholas, Maunder, Benjamin and , 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. ISSN 0012-821X

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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.

Item Type: Article
Additional Information: Acknowledgments: 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).
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: LivePure Connector
Date Deposited: 20 Apr 2022 15:30
Last Modified: 24 May 2022 14:55
URI: https://ueaeprints.uea.ac.uk/id/eprint/84700
DOI: 10.1016/j.epsl.2022.117535

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