Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing.
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| Title: | Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing. |
|---|---|
| Authors: | Audet, Pascal, Bostock, Michael G., Christensen, Nikolas I., Peacock, Simon M. |
| Source: | Nature. 1/1/2009, Vol. 457 Issue 7225, p76-78. 3p. 1 Diagram, 1 Graph, 1 Map. |
| Subjects: | Subduction zones, Geodynamics, Ocean bottom, Research methodology, Scientific observation, Poisson's ratio, Paleoseismology, Core-mantle boundary |
| Abstract: | Water and hydrous minerals play a key part in geodynamic processes at subduction zones by weakening the plate boundary, aiding slip and permitting subduction—and indeed plate tectonics—to occur. The seismological signature of water within the forearc mantle wedge is evident in anomalies with low seismic shear velocity marking serpentinization. However, seismological observations bearing on the presence of water within the subducting plate itself are less well documented. Here we use converted teleseismic waves to obtain observations of anomalously high Poisson’s ratios within the subducted oceanic crust from the Cascadia continental margin to its intersection with forearc mantle. On the basis of pressure, temperature and compositional considerations, the elevated Poisson’s ratios indicate that water is pervasively present in fluid form at pore pressures near lithostatic values. Combined with observations of a strong negative velocity contrast at the top of the oceanic crust, our results imply that the megathrust is a low-permeability boundary. The transition from a low- to high-permeability plate interface downdip into the mantle wedge is explained by hydrofracturing of the seal by volume changes across the interface caused by the onset of crustal eclogitization and mantle serpentinization. These results may have important implications for our understanding of seismogenesis, subduction zone structure and the mechanism of episodic tremor and slip. [ABSTRACT FROM AUTHOR] |
| Copyright of Nature is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.) | |
| Database: | Psychology and Behavioral Sciences Collection |
| FullText | Links: – Type: pdflink Text: Availability: 0 |
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| Header | DbId: pbh DbLabel: Psychology and Behavioral Sciences Collection An: 35886894 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Audet%2C+Pascal%22">Audet, Pascal</searchLink><br /><searchLink fieldCode="AR" term="%22Bostock%2C+Michael+G%2E%22">Bostock, Michael G.</searchLink><br /><searchLink fieldCode="AR" term="%22Christensen%2C+Nikolas+I%2E%22">Christensen, Nikolas I.</searchLink><br /><searchLink fieldCode="AR" term="%22Peacock%2C+Simon+M%2E%22">Peacock, Simon M.</searchLink> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Nature%22">Nature</searchLink>. 1/1/2009, Vol. 457 Issue 7225, p76-78. 3p. 1 Diagram, 1 Graph, 1 Map. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Subduction+zones%22">Subduction zones</searchLink><br /><searchLink fieldCode="DE" term="%22Geodynamics%22">Geodynamics</searchLink><br /><searchLink fieldCode="DE" term="%22Ocean+bottom%22">Ocean bottom</searchLink><br /><searchLink fieldCode="DE" term="%22Research+methodology%22">Research methodology</searchLink><br /><searchLink fieldCode="DE" term="%22Scientific+observation%22">Scientific observation</searchLink><br /><searchLink fieldCode="DE" term="%22Poisson's+ratio%22">Poisson's ratio</searchLink><br /><searchLink fieldCode="DE" term="%22Paleoseismology%22">Paleoseismology</searchLink><br /><searchLink fieldCode="DE" term="%22Core-mantle+boundary%22">Core-mantle boundary</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: Water and hydrous minerals play a key part in geodynamic processes at subduction zones by weakening the plate boundary, aiding slip and permitting subduction—and indeed plate tectonics—to occur. The seismological signature of water within the forearc mantle wedge is evident in anomalies with low seismic shear velocity marking serpentinization. However, seismological observations bearing on the presence of water within the subducting plate itself are less well documented. Here we use converted teleseismic waves to obtain observations of anomalously high Poisson’s ratios within the subducted oceanic crust from the Cascadia continental margin to its intersection with forearc mantle. On the basis of pressure, temperature and compositional considerations, the elevated Poisson’s ratios indicate that water is pervasively present in fluid form at pore pressures near lithostatic values. Combined with observations of a strong negative velocity contrast at the top of the oceanic crust, our results imply that the megathrust is a low-permeability boundary. The transition from a low- to high-permeability plate interface downdip into the mantle wedge is explained by hydrofracturing of the seal by volume changes across the interface caused by the onset of crustal eclogitization and mantle serpentinization. These results may have important implications for our understanding of seismogenesis, subduction zone structure and the mechanism of episodic tremor and slip. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Nature is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.) |
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| RecordInfo | BibRecord: BibEntity: Identifiers: – Type: doi Value: 10.1038/nature07650 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 3 StartPage: 76 Subjects: – SubjectFull: Subduction zones Type: general – SubjectFull: Geodynamics Type: general – SubjectFull: Ocean bottom Type: general – SubjectFull: Research methodology Type: general – SubjectFull: Scientific observation Type: general – SubjectFull: Poisson's ratio Type: general – SubjectFull: Paleoseismology Type: general – SubjectFull: Core-mantle boundary Type: general Titles: – TitleFull: Seismic evidence for overpressured subducted oceanic crust and megathrust fault sealing. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Audet, Pascal – PersonEntity: Name: NameFull: Bostock, Michael G. – PersonEntity: Name: NameFull: Christensen, Nikolas I. – PersonEntity: Name: NameFull: Peacock, Simon M. IsPartOfRelationships: – BibEntity: Dates: – D: 01 M: 01 Text: 1/1/2009 Type: published Y: 2009 Identifiers: – Type: issn-print Value: 00280836 Numbering: – Type: volume Value: 457 – Type: issue Value: 7225 Titles: – TitleFull: Nature Type: main |
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