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Geophysical implications of Izu–Bonin mantle wedge hydration from chemical geodynamic modeling

Hebert, Laura B. and Gurnis, Michael (2010) Geophysical implications of Izu–Bonin mantle wedge hydration from chemical geodynamic modeling. Island Arc, 19 (1). pp. 134-150. ISSN 1038-4871. doi:10.1111/j.1440-1738.2009.00688.x.

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Using two-dimensional dynamic models of the Northern Izu–Bonin (NIB) subduction zone, we show that a particular localized low-viscosity (η_(LV) = 3.3 × 10^(19) − 4.0 × 10^(20) Pa s), low-density (Δρ ~ −10 kg/m^3 relative to ambient mantle) geometry within the wedge is required to match surface observations of topography, gravity, and geoid anomalies. The hydration structure resulting in this low-viscosity, low-density geometry develops due to fluid release into the wedge within a depth interval from 150 to 350 km and is consistent with results from coupled geochemical and geodynamic modeling of the NIB subduction system and from previous uncoupled models of the wedge beneath the Japan arcs. The source of the fluids can be either subducting lithospheric serpentinite or stable hydrous phases in the wedge such as serpentine or chlorite. On the basis of this modeling, predictions can be made as to the specific low-viscosity geometries associated with geophysical surface observables for other subduction zones based on regional subduction parameters such as subducting slab age.

Item Type:Article
Related URLs:
Gurnis, Michael0000-0003-1704-597X
Additional Information:© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Asia Pty Ltd. Received 16 August 2008; accepted for publication 16 March 2009. The authors thank P. Antoshechkina, P. Asimow, and C. Hall for collaboration with the GyPSM-S modeling effort, and L. DiCaprio and E. Tan for helpful discussions and technical advice. Special thanks to S. Honda and H. Iwamori for very helpful reviews, and to editor Y. Tamura. Support was provided through the Tectonics Observatory by the Gordon and Betty Moore Foundation. This is Contribution Number 106 of the Tectonics Observatory and 10018 of the Division of Geological and Planetary Sciences, California Institute of Technology.
Group:Seismological Laboratory
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:geoid; gravity; GyPSM-S; Izu-Bonin; low-viscosity channel; topography
Issue or Number:1
Record Number:CaltechAUTHORS:20100315-153841139
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:17739
Deposited By: Tony Diaz
Deposited On:22 Mar 2010 03:25
Last Modified:08 Nov 2021 23:38

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