The subductability of continental lithosphere: the before and after story

The temporal evolution of internal forces in a collision environment controls first-order characteristics such as convergence rate, slab dip, subduction stall, and slab breakoff, amongst others. Foremost among these forces are the positive buoyancy provided by the subduction of felsic continental ma...

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Autores: Afonso, Juan Carlos, Zlotnik, Sergio|||0000-0001-9674-8950
Tipo de recurso: artículo
Fecha de publicación:2011
País:España
Institución:Universitat Politècnica de Catalunya (UPC)
Repositorio:UPCommons. Portal del coneixement obert de la UPC
Idioma:inglés
OAI Identifier:oai:upcommons.upc.edu:2117/81857
Acceso en línea:https://hdl.handle.net/2117/81857
https://dx.doi.org/10.1007/978-3-540-88558-0_3
Access Level:acceso abierto
Palabra clave:Geophysica
Geofísica
Classificació AMS::86 Geophysics
Àrees temàtiques de la UPC::Matemàtiques i estadística::Anàlisi numèrica::Modelització matemàtica
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spelling The subductability of continental lithosphere: the before and after storyAfonso, Juan CarlosZlotnik, Sergio|||0000-0001-9674-8950GeophysicaGeofísicaClassificació AMS::86 GeophysicsÀrees temàtiques de la UPC::Matemàtiques i estadística::Anàlisi numèrica::Modelització matemàticaThe temporal evolution of internal forces in a collision environment controls first-order characteristics such as convergence rate, slab dip, subduction stall, and slab breakoff, amongst others. Foremost among these forces are the positive buoyancy provided by the subduction of felsic continental material and the negative buoyancy associated with the slab. In this work we use fully dynamic thermomechanical models coupled with thermodynamic/petrological formalisms to study the evolution of these forces during a continent–arc/microcontinent collision and their influence on the large-scale dynamics of the system. Two distinctive features of our models that allow a self-consistent assessment of collision dynamics are: (1) the use of a new thermodynamic database valid up to ~25–30 GPa that includes most of the major phases relevant to continental subduction, and (2) a fully dynamic approach in which no velocities are imposed to either force or stop subduction. The former allows realistic computations of the buoyancy forces driving the system as a function of P-T-composition. The latter assures that computed velocities emerge self-consistently in our simulations in response to the balance between internal forces in our numerical domain. The main results from our experiments can be summarized as follows. (1) The delamination of the lithospheric mantle after a short episode of continental subduction is a viable scenario to end continental subduction; the associated evolution of convergence is comparable to those proposed for real collision setting. (2) We corroborate previous results showing that the main control on the dynamics and final configuration (type of slab breakoff) of the collision is the rheology and composition of the continental crust; strong mafic crusts favor deep subduction and recycling of significant volumes of continental material, while soft felsic crusts preclude them. (3) Subducted continental crust remains buoyant with respect to the surrounding mantle down to depths of ~250–300 km, thus allowing exhumation of deeply subducted crust as long as a detachment from the slab occurs. (4) Realistic compositional stratifications in the continental lithospheric mantle exert only a modest influence on the overall evolution of the collision system. (5) Subducted continental crust to depths >250–300 km becomes significantly denser than the surrounding mantle due to the appearance in the solid assemblage of high-density phases such as hollandite and stishovite; this provides extra negative buoyancy to the slab and precludes the exhumation of crustal components. This supports the idea of the existence of a “depth of no return” for continental material at around 250 km depth.Peer Reviewed20112011-01-0120162016-01-22journal articlehttp://purl.org/coar/resource_type/c_6501AMhttp://purl.org/coar/version/c_ab4af688f83e57aainfo:eu-repo/semantics/articleapplication/pdfhttps://hdl.handle.net/2117/81857https://dx.doi.org/10.1007/978-3-540-88558-0_3reponame:UPCommons. Portal del coneixement obert de la UPCinstname:Universitat Politècnica de Catalunya (UPC)Inglésengopen accesshttp://purl.org/coar/access_right/c_abf2http://creativecommons.org/licenses/by-nc-nd/3.0/es/info:eu-repo/semantics/openAccessoai:upcommons.upc.edu:2117/818572026-05-27T15:37:01Z
dc.title.none.fl_str_mv The subductability of continental lithosphere: the before and after story
title The subductability of continental lithosphere: the before and after story
spellingShingle The subductability of continental lithosphere: the before and after story
Afonso, Juan Carlos
Geophysica
Geofísica
Classificació AMS::86 Geophysics
Àrees temàtiques de la UPC::Matemàtiques i estadística::Anàlisi numèrica::Modelització matemàtica
title_short The subductability of continental lithosphere: the before and after story
title_full The subductability of continental lithosphere: the before and after story
title_fullStr The subductability of continental lithosphere: the before and after story
title_full_unstemmed The subductability of continental lithosphere: the before and after story
title_sort The subductability of continental lithosphere: the before and after story
dc.creator.none.fl_str_mv Afonso, Juan Carlos
Zlotnik, Sergio|||0000-0001-9674-8950
author Afonso, Juan Carlos
author_facet Afonso, Juan Carlos
Zlotnik, Sergio|||0000-0001-9674-8950
author_role author
author2 Zlotnik, Sergio|||0000-0001-9674-8950
author2_role author
dc.subject.none.fl_str_mv Geophysica
Geofísica
Classificació AMS::86 Geophysics
Àrees temàtiques de la UPC::Matemàtiques i estadística::Anàlisi numèrica::Modelització matemàtica
topic Geophysica
Geofísica
Classificació AMS::86 Geophysics
Àrees temàtiques de la UPC::Matemàtiques i estadística::Anàlisi numèrica::Modelització matemàtica
description The temporal evolution of internal forces in a collision environment controls first-order characteristics such as convergence rate, slab dip, subduction stall, and slab breakoff, amongst others. Foremost among these forces are the positive buoyancy provided by the subduction of felsic continental material and the negative buoyancy associated with the slab. In this work we use fully dynamic thermomechanical models coupled with thermodynamic/petrological formalisms to study the evolution of these forces during a continent–arc/microcontinent collision and their influence on the large-scale dynamics of the system. Two distinctive features of our models that allow a self-consistent assessment of collision dynamics are: (1) the use of a new thermodynamic database valid up to ~25–30 GPa that includes most of the major phases relevant to continental subduction, and (2) a fully dynamic approach in which no velocities are imposed to either force or stop subduction. The former allows realistic computations of the buoyancy forces driving the system as a function of P-T-composition. The latter assures that computed velocities emerge self-consistently in our simulations in response to the balance between internal forces in our numerical domain. The main results from our experiments can be summarized as follows. (1) The delamination of the lithospheric mantle after a short episode of continental subduction is a viable scenario to end continental subduction; the associated evolution of convergence is comparable to those proposed for real collision setting. (2) We corroborate previous results showing that the main control on the dynamics and final configuration (type of slab breakoff) of the collision is the rheology and composition of the continental crust; strong mafic crusts favor deep subduction and recycling of significant volumes of continental material, while soft felsic crusts preclude them. (3) Subducted continental crust remains buoyant with respect to the surrounding mantle down to depths of ~250–300 km, thus allowing exhumation of deeply subducted crust as long as a detachment from the slab occurs. (4) Realistic compositional stratifications in the continental lithospheric mantle exert only a modest influence on the overall evolution of the collision system. (5) Subducted continental crust to depths >250–300 km becomes significantly denser than the surrounding mantle due to the appearance in the solid assemblage of high-density phases such as hollandite and stishovite; this provides extra negative buoyancy to the slab and precludes the exhumation of crustal components. This supports the idea of the existence of a “depth of no return” for continental material at around 250 km depth.
publishDate 2011
dc.date.none.fl_str_mv 2011
2011-01-01
2016
2016-01-22
dc.type.none.fl_str_mv journal article
http://purl.org/coar/resource_type/c_6501
AM
http://purl.org/coar/version/c_ab4af688f83e57aa
dc.type.openaire.fl_str_mv info:eu-repo/semantics/article
format article
dc.identifier.none.fl_str_mv https://hdl.handle.net/2117/81857
https://dx.doi.org/10.1007/978-3-540-88558-0_3
url https://hdl.handle.net/2117/81857
https://dx.doi.org/10.1007/978-3-540-88558-0_3
dc.language.none.fl_str_mv Inglés
eng
language_invalid_str_mv Inglés
language eng
dc.rights.none.fl_str_mv open access
http://purl.org/coar/access_right/c_abf2

http://creativecommons.org/licenses/by-nc-nd/3.0/es/
dc.rights.openaire.fl_str_mv info:eu-repo/semantics/openAccess
rights_invalid_str_mv open access
http://purl.org/coar/access_right/c_abf2

http://creativecommons.org/licenses/by-nc-nd/3.0/es/
eu_rights_str_mv openAccess
dc.format.none.fl_str_mv application/pdf
dc.source.none.fl_str_mv reponame:UPCommons. Portal del coneixement obert de la UPC
instname:Universitat Politècnica de Catalunya (UPC)
instname_str Universitat Politècnica de Catalunya (UPC)
reponame_str UPCommons. Portal del coneixement obert de la UPC
collection UPCommons. Portal del coneixement obert de la UPC
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