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Fluid source-based modeling of melt initiation within the subduction zone mantle wedge: Implications for geochemical trends in arc lavas

Hebert, Laura Baker and Asimow, Paul D. and Antoshechkina, Paula (2009) Fluid source-based modeling of melt initiation within the subduction zone mantle wedge: Implications for geochemical trends in arc lavas. Chemical Geology, 266 (3-4). pp. 297-310. ISSN 0009-2541.

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The GyPSM-S (Geodynamic and Petrological Synthesis Model for Subduction) scheme couples a petrological model with a 2-D thermal and variable viscosity flow model to describe and compare fundamental processes occurring within the subduction mantle wedge, including the development of a low-viscosity channel (LVC) (Hebert et al., 2009, Earth and Planetary Science Letters, v. 278, p. 243–256). Here we supplement the basic coupled model result with more sophisticated treatments of trace element partitioning in the fluid phase and melt transport regimes. We investigate the influences of slab fluid source lithology and fluid transport mechanisms on melt geochemistry, the implications of mantle source depletion related to fluid fluxing, and potential melt migration processes. This study describes two model cases that can be compared to geochemical datasets for the Izu–Bonin intra-oceanic subduction system and the Central Costa Rican part of the Central American arc. We find that there is a progression of geochemical characteristics described in studies of cross-arc and along-arc lavas that can be approximated assuming (i) limited fluid–rock interaction within the mantle wedge and (ii) that melt migration preserves the spatial distinction among melts initiated in different areas of the wedge. Specifically, volcanic front lavas have significant contributions from shallower slab fluid sources, and rear-arc lavas have significant contributions from deeper slab fluid sources. Evidence for limited fluid–rock interaction could imply either a rapid fluid transport mechanism or a fluid-dominated trace element budget within the LVC. Although we do not include a back-arc in these models, interpretations of the results lead to several potential mechanisms to explain hydrous inputs to back-arc source regions.

Item Type:Article
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URLURL TypeDescription
Asimow, Paul D.0000-0001-6025-8925
Antoshechkina, Paula0000-0002-3358-5186
Additional Information:© 2009 Elsevier. Received 30 August 2008; revised 15 April 2009; accepted 15 June 2009. Editor: D.B. Dingwell. Available online 25 June 2009. he authors would like to thank C. Hall and M. Gurnis for collaboration in the GyPSM-S modeling effort. We additionally thank editors Paul Hall, Stephanie Escrig and D.B. Dingwell. Very helpful reviews were provided by James Conder and an anonymous reviewer. Support was provided through the Tectonics Observatory by the Gordon and Betty Moore Foundation.
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Subject Keywords:Costa Rica; Izu–Bonin; Subduction; Volcanic front; Cross-arc trends; GyPSM-S
Issue or Number:3-4
Record Number:CaltechAUTHORS:20091022-152025976
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:16465
Deposited By: George Porter
Deposited On:22 Oct 2009 22:53
Last Modified:29 Oct 2019 19:46

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