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Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges

Title: Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges.
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Name(s): Manthilake, Geeth, author
Bolfan-Casanova, Nathalie, author
Novella, Davide, author
Mookherjee, Mainak, author
Andrault, Denis, author
Type of Resource: text
Genre: Text
Date Issued: 2016-05
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: Mantle wedge regions in subduction zone settings show anomalously high electrical conductivity (similar to 1 S/m) that has often been attributed to the presence of aqueous fluids released by slab dehydration. Laboratory-based measurements of the electrical conductivity of hydrous phases and aqueous fluids are significantly lower and cannot readily explain the geophysically observed anomalously high electrical conductivity. The released aqueous fluid also rehydrates the mantle wedge and stabilizes a suite of hydrous phases, including serpentine and chlorite. In this present study, we have measured the electrical conductivity of a natural chlorite at pressures and temperatures relevant for the subduction zone setting. In our experiment, we observe two distinct conductivity enhancements when chlorite is heated to temperatures beyond its thermodynamic stability field. The initial increase in electrical conductivity to similar to 3 x 10(-3) S/m can be attributed to chlorite dehydration and the release of aqueous fluids. This is followed by a unique, subsequent enhancement of electrical conductivity of up to 7 x 10(-1) S/m. This is related to the growth of an interconnected network of a highly conductive and chemically impure magnetite mineral phase. Thus, the dehydration of chlorite and associated processes are likely to be crucial in explaining the anomalously high electrical conductivity observed in mantle wedges. Chlorite dehydration in the mantle wedge provides an additional source of aqueous fluid above the slab and could also be responsible for the fixed depth (120 +/- 40 km) of melting at the top of the subducting slab beneath the subduction-related volcanic arc front.
Identifier: FSU_libsubv1_wos_000380073000012 (IID), 10.1126/sciadv.1501631 (DOI)
Keywords: crust, fluid, gpa, magnetite, pressures, resistivity, southwestern japan, stability, subduction zone, temperatures
Publication Note: The publisher’s version of record is available at http://www.dx.doi.org/10.1126/sciadv.1501631
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000380073000012
Owner Institution: FSU
Is Part Of: Science Advances.
2375-2548
Issue: iss. 5, vol. 2

Choose the citation style.
Manthilake, G., Bolfan-Casanova, N., Novella, D., Mookherjee, M., & Andrault, D. (2016). Dehydration of chlorite explains anomalously high electrical conductivity in the mantle wedges. Science Advances. Retrieved from http://purl.flvc.org/fsu/fd/FSU_libsubv1_wos_000380073000012