H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones.
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| Title: | H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones. |
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| Authors: | Labrousse, L.1,2 loic.labrousse@upmc.fr, Duretz, T.3, Gerya, T.4 |
| Source: | Earth & Planetary Science Letters. Oct2015, Vol. 428, p151-161. 11p. |
| Subjects: | Subduction zones, Continental crust, Exhumation, High pressure (Technology), Rock mechanics |
| Abstract: | We present two-dimensional numerical models of plate subduction and collision inspired by the Scandinavian Caledonian orogeny to investigate the possible impact of continental crust partial melting on the exhumation of ultra-high pressure metamorphic rocks. Three possible reactions were tested: low temperature solidus representing H 2 O-fluid-saturated partial melting, and two end-member reaction curves for dehydration melting. Thermo-mechanical effects of partial melting were implemented as (1) a viscosity decrease as a determined rheologically critical melt percentage was reached (here 0.1), (2) a change in effective heat capacity and adiabatic heating/cooling accounting for a latent heat term in the heat equation. Among the 3 tested reactions, only H 2 O-fluid-saturated partial melting drastically modifies the collision dynamics from the non-melting reference model holding all other parameters constant. A substantially low general viscosity truncation (here 10 17 Pa s) is needed to properly resolve the effect of partial melting on deep collision processes. Low temperature melting indeed induces the development of a low viscosity buoyant plume prior to slab detachment, where migmatites exhume from UHP conditions at rates and with pressure–temperature paths similar to the natural values acknowledged for the Norwegian Caledonides. High temperature melting has no drastic influence on early collision dynamics. While positive buoyancy remains the first order driver for the exhumation of buried continental rocks, exhumation initiates in these cases with eduction subsequent to slab detachment. Melting and formation of a migmatite plume can later occur along decompression path while continental crust undergoes thermal reequilibration at temperatures above 900 °C. Some of the partially molten material can also relaminate in the overriding plate rather than exhume within the collision zone. Even if minor in terms of amount of magma produced, H 2 O-fluid-saturated partial melting at UHP conditions could therefore have a dramatic rheological effect and actually limits continental rocks subduction and facilitates their exhumation. [ABSTRACT FROM AUTHOR] |
| Copyright of Earth & Planetary Science Letters is the property of Elsevier B.V. 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.) | |
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| Header | DbId: egs DbLabel: Engineering Source An: 108965735 AccessLevel: 6 PubType: Academic Journal PubTypeId: academicJournal PreciseRelevancyScore: 0 |
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| Items | – Name: Title Label: Title Group: Ti Data: H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones. – Name: Author Label: Authors Group: Au Data: <searchLink fieldCode="AR" term="%22Labrousse%2C+L%2E%22">Labrousse, L.</searchLink><relatesTo>1,2</relatesTo><i> loic.labrousse@upmc.fr</i><br /><searchLink fieldCode="AR" term="%22Duretz%2C+T%2E%22">Duretz, T.</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Gerya%2C+T%2E%22">Gerya, T.</searchLink><relatesTo>4</relatesTo> – Name: TitleSource Label: Source Group: Src Data: <searchLink fieldCode="JN" term="%22Earth+%26+Planetary+Science+Letters%22">Earth & Planetary Science Letters</searchLink>. Oct2015, Vol. 428, p151-161. 11p. – Name: Subject Label: Subjects Group: Su Data: <searchLink fieldCode="DE" term="%22Subduction+zones%22">Subduction zones</searchLink><br /><searchLink fieldCode="DE" term="%22Continental+crust%22">Continental crust</searchLink><br /><searchLink fieldCode="DE" term="%22Exhumation%22">Exhumation</searchLink><br /><searchLink fieldCode="DE" term="%22High+pressure+%28Technology%29%22">High pressure (Technology)</searchLink><br /><searchLink fieldCode="DE" term="%22Rock+mechanics%22">Rock mechanics</searchLink> – Name: Abstract Label: Abstract Group: Ab Data: We present two-dimensional numerical models of plate subduction and collision inspired by the Scandinavian Caledonian orogeny to investigate the possible impact of continental crust partial melting on the exhumation of ultra-high pressure metamorphic rocks. Three possible reactions were tested: low temperature solidus representing H 2 O-fluid-saturated partial melting, and two end-member reaction curves for dehydration melting. Thermo-mechanical effects of partial melting were implemented as (1) a viscosity decrease as a determined rheologically critical melt percentage was reached (here 0.1), (2) a change in effective heat capacity and adiabatic heating/cooling accounting for a latent heat term in the heat equation. Among the 3 tested reactions, only H 2 O-fluid-saturated partial melting drastically modifies the collision dynamics from the non-melting reference model holding all other parameters constant. A substantially low general viscosity truncation (here 10 17 Pa s) is needed to properly resolve the effect of partial melting on deep collision processes. Low temperature melting indeed induces the development of a low viscosity buoyant plume prior to slab detachment, where migmatites exhume from UHP conditions at rates and with pressure–temperature paths similar to the natural values acknowledged for the Norwegian Caledonides. High temperature melting has no drastic influence on early collision dynamics. While positive buoyancy remains the first order driver for the exhumation of buried continental rocks, exhumation initiates in these cases with eduction subsequent to slab detachment. Melting and formation of a migmatite plume can later occur along decompression path while continental crust undergoes thermal reequilibration at temperatures above 900 °C. Some of the partially molten material can also relaminate in the overriding plate rather than exhume within the collision zone. Even if minor in terms of amount of magma produced, H 2 O-fluid-saturated partial melting at UHP conditions could therefore have a dramatic rheological effect and actually limits continental rocks subduction and facilitates their exhumation. [ABSTRACT FROM AUTHOR] – Name: AbstractSuppliedCopyright Label: Group: Ab Data: <i>Copyright of Earth & Planetary Science Letters is the property of Elsevier B.V. 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: 10.1016/j.epsl.2015.06.016 Languages: – Code: eng Text: English PhysicalDescription: Pagination: PageCount: 11 StartPage: 151 Subjects: – SubjectFull: Subduction zones Type: general – SubjectFull: Continental crust Type: general – SubjectFull: Exhumation Type: general – SubjectFull: High pressure (Technology) Type: general – SubjectFull: Rock mechanics Type: general Titles: – TitleFull: H2O-fluid-saturated melting of subducted continental crust facilitates exhumation of ultrahigh-pressure rocks in continental subduction zones. Type: main BibRelationships: HasContributorRelationships: – PersonEntity: Name: NameFull: Labrousse, L. – PersonEntity: Name: NameFull: Duretz, T. – PersonEntity: Name: NameFull: Gerya, T. IsPartOfRelationships: – BibEntity: Dates: – D: 15 M: 10 Text: Oct2015 Type: published Y: 2015 Identifiers: – Type: issn-print Value: 0012821X Numbering: – Type: volume Value: 428 Titles: – TitleFull: Earth & Planetary Science Letters Type: main |
| ResultId | 1 |
