Nagaya, T, Walker, AM orcid.org/0000-0003-3121-3255, Wookey, J et al. (3 more authors) (2016) Seismic evidence for flow in the hydrated mantle wedge of the Ryukyu subduction zone. Scientific Reports, 6. 29981. ISSN 2045-2322
Abstract
It is widely accepted that water-rich serpentinite domains are commonly present in the mantle above shallow subducting slabs and play key roles in controlling the geochemical cycling and physical properties of subduction zones. Thermal and petrological models show the dominant serpentine mineral is antigorite. However, there is no good consensus on the amount, distribution and alignment of this mineral. Seismic velocities are commonly used to identify antigorite-rich domains, but antigorite is highly-anisotropic and depending on the seismic ray path, its properties can be very difficult to distinguish from non-hydrated olivine-rich mantle. Here, we utilize this anisotropy and show how an analysis of seismic anisotropy that incorporates measured ray path geometries in the Ryukyu arc can constrain the distribution, orientation and amount of antigorite. We find more than 54% of the wedge must consist of antigorite and the alignment must change from vertically aligned to parallel to the slab. This orientation change suggests convective flow in the hydrated forearc mantle. Shear wave splitting analysis in other subduction zones indicates large-scale serpentinization and forearc mantle convection are likely to be more widespread than generally recognized. The view that the forearc mantle of cold subduction zones is dry needs to be reassessed.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © The Author(s), 2016. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ |
Keywords: | Structural geology; Seismology; Geodynamics; Geophysics |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Inst of Geophysics and Tectonics (IGT) (Leeds) |
Funding Information: | Funder Grant number NERC NE/K008803/1 NERC NE/M000044/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 21 Jul 2016 10:13 |
Last Modified: | 20 May 2019 14:30 |
Published Version: | https://doi.org/10.1038/srep29981 |
Status: | Published |
Publisher: | Nature Publishing Group |
Identification Number: | 10.1038/srep29981 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:102706 |
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