On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone
Abstract Seismic anisotropy mainly originates from the crystallographic preferred orientation (CPO) of minerals deformed in the convective mantle flow. While fabric transitions have been previously observed in experiments, their influence on large‐scale anisotropy is not well‐documented. Here, we im...
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| Format: | Article |
| Language: | English |
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Wiley
2025-03-01
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| Series: | Geochemistry, Geophysics, Geosystems |
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| Online Access: | https://doi.org/10.1029/2024GC011827 |
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| author | John Keith Magali Christine Thomas Estelle Elisa Ledoux Yann Capdeville Sébastien Merkel |
| author_facet | John Keith Magali Christine Thomas Estelle Elisa Ledoux Yann Capdeville Sébastien Merkel |
| author_sort | John Keith Magali |
| collection | DOAJ |
| description | Abstract Seismic anisotropy mainly originates from the crystallographic preferred orientation (CPO) of minerals deformed in the convective mantle flow. While fabric transitions have been previously observed in experiments, their influence on large‐scale anisotropy is not well‐documented. Here, we implement 2D geodynamic models of intra‐oceanic subduction coupled with mantle fabric modeling to investigate the combined effect of pressure (P)‐and water‐dependent microscopic flow properties of upper mantle and upper transition zone (UTZ) minerals, respectively, on large‐scale anisotropy. We then compare our anisotropy models with anisotropic tomography observations across the Honshu subduction zone. Our results for the upper mantle correlate well with observations, implying that the P‐dependence of olivine fabrics is sufficient to explain the variability of anisotropy. Meanwhile, a dry UTZ tends to be near‐isotropic whereas a relatively wet UTZ could produce up to 1% azimuthal and ∼2% radial anisotropy. Because water facilitates CPO development, it is therefore likely a requirement to explain the presence of anisotropy in the transition zone close to subducting slabs. |
| format | Article |
| id | doaj-art-2bb53ae46fda4e138b92f782acf1e0bb |
| institution | OA Journals |
| issn | 1525-2027 |
| language | English |
| publishDate | 2025-03-01 |
| publisher | Wiley |
| record_format | Article |
| series | Geochemistry, Geophysics, Geosystems |
| spelling | doaj-art-2bb53ae46fda4e138b92f782acf1e0bb2025-08-20T02:10:38ZengWileyGeochemistry, Geophysics, Geosystems1525-20272025-03-01263n/an/a10.1029/2024GC011827On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction ZoneJohn Keith Magali0Christine Thomas1Estelle Elisa Ledoux2Yann Capdeville3Sébastien Merkel4Institute of Geophysics University of Münster Münster GermanyInstitute of Geophysics University of Münster Münster GermanyDepartment of Geology and Geophysics University of Utah Salt Lake City UT USALaboratoire de Planétologie et Géodynamique CNRS UMR 6112 Université de Nantes Nantes FranceUniversité de Lille CNRS INRAE Centrale Lille UMR 8207—UMET—Unité Matériaux et Transformations Lille FranceAbstract Seismic anisotropy mainly originates from the crystallographic preferred orientation (CPO) of minerals deformed in the convective mantle flow. While fabric transitions have been previously observed in experiments, their influence on large‐scale anisotropy is not well‐documented. Here, we implement 2D geodynamic models of intra‐oceanic subduction coupled with mantle fabric modeling to investigate the combined effect of pressure (P)‐and water‐dependent microscopic flow properties of upper mantle and upper transition zone (UTZ) minerals, respectively, on large‐scale anisotropy. We then compare our anisotropy models with anisotropic tomography observations across the Honshu subduction zone. Our results for the upper mantle correlate well with observations, implying that the P‐dependence of olivine fabrics is sufficient to explain the variability of anisotropy. Meanwhile, a dry UTZ tends to be near‐isotropic whereas a relatively wet UTZ could produce up to 1% azimuthal and ∼2% radial anisotropy. Because water facilitates CPO development, it is therefore likely a requirement to explain the presence of anisotropy in the transition zone close to subducting slabs.https://doi.org/10.1029/2024GC011827transition zonewadsleyiteolivinetexturesubductionanisotropy |
| spellingShingle | John Keith Magali Christine Thomas Estelle Elisa Ledoux Yann Capdeville Sébastien Merkel On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone Geochemistry, Geophysics, Geosystems transition zone wadsleyite olivine texture subduction anisotropy |
| title | On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone |
| title_full | On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone |
| title_fullStr | On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone |
| title_full_unstemmed | On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone |
| title_short | On the Influence of Pressure, Phase Transitions, and Water on Large‐Scale Seismic Anisotropy Underneath a Subduction Zone |
| title_sort | on the influence of pressure phase transitions and water on large scale seismic anisotropy underneath a subduction zone |
| topic | transition zone wadsleyite olivine texture subduction anisotropy |
| url | https://doi.org/10.1029/2024GC011827 |
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