Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology
Autor(a) principal: | |
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Data de Publicação: | 2012 |
Outros Autores: | , , , , |
Tipo de documento: | Artigo |
Idioma: | eng |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10174/5440 |
Resumo: | New U–Pb and 40Ar–39Ar geochronology and structural data from high- tomedium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U–Pb age of 465±14Ma (Middle Ordovician) measured on migmatite from the Coimbra–Cordoba shear zone is interpreted as the age of protolith crystallization. This age determination revises the information contained in the geological map of Portugal, in which these rocks were considered to be Proterozoic in age. This paper describes the evolution of Variscan wrench tectonics related to the development of shear zones, exhumation of deep crustal rocks and emplacement of magma in the Ossa-Morena Zone basement. In the Coimbra–Cordoba shear zone (transpressional), migmatites were rapidly exhumed from a depth of 42.5km to 16.6km over a period of ca. 10Ma in the Viséan (ca. 340–330Ma), indicating oblique slip exhumation rates of 8.5 to 10.6mm/yr (Campo Maior migmatites) and 3.2mm/yr (Ouguela gneisses) respectively. In the Évora Massif, the gneisses of the Boa Fé shear zone (transtensional) were exhumed from 18.5 to 7.4km depth in the period ca. 344–334Ma (Viséan), with exhumation oblique slip rates of 2.8 to 4.2mm/yr. At the same time, the Early Carboniferous basins of SW Iberia were filled by turbidites and olistoliths, composed mostly of Devonian rocks. The presence of olistoliths indicates significant tectonic instability during sedimen- tation with large-scale mass movement, probably in the form of gravity slides. Deformation and metamor- phism dated at 356±12Ma, 321±13Ma and 322±29Ma respectively suggests that Variscan wrench movements were active in SW Iberia during the Early Carboniferous for a period of at least 35Ma. |
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Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronologyVariscan beltWrench tectonicsTiming of deformationBasin instabilityOssa-Morena ZoneSouth Portuguese ZoneNew U–Pb and 40Ar–39Ar geochronology and structural data from high- tomedium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U–Pb age of 465±14Ma (Middle Ordovician) measured on migmatite from the Coimbra–Cordoba shear zone is interpreted as the age of protolith crystallization. This age determination revises the information contained in the geological map of Portugal, in which these rocks were considered to be Proterozoic in age. This paper describes the evolution of Variscan wrench tectonics related to the development of shear zones, exhumation of deep crustal rocks and emplacement of magma in the Ossa-Morena Zone basement. In the Coimbra–Cordoba shear zone (transpressional), migmatites were rapidly exhumed from a depth of 42.5km to 16.6km over a period of ca. 10Ma in the Viséan (ca. 340–330Ma), indicating oblique slip exhumation rates of 8.5 to 10.6mm/yr (Campo Maior migmatites) and 3.2mm/yr (Ouguela gneisses) respectively. In the Évora Massif, the gneisses of the Boa Fé shear zone (transtensional) were exhumed from 18.5 to 7.4km depth in the period ca. 344–334Ma (Viséan), with exhumation oblique slip rates of 2.8 to 4.2mm/yr. At the same time, the Early Carboniferous basins of SW Iberia were filled by turbidites and olistoliths, composed mostly of Devonian rocks. The presence of olistoliths indicates significant tectonic instability during sedimen- tation with large-scale mass movement, probably in the form of gravity slides. Deformation and metamor- phism dated at 356±12Ma, 321±13Ma and 322±29Ma respectively suggests that Variscan wrench movements were active in SW Iberia during the Early Carboniferous for a period of at least 35Ma.Elsevier2012-11-12T11:46:37Z2012-11-122012-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articlehttp://hdl.handle.net/10174/5440http://hdl.handle.net/10174/5440eng558-559Tectonophysicsmpereira@uevora.ptndndndndnd250Pereira, M. FranciscoChichorro, M.Silva, J. BrandãoOrdonez-Casado, B.Lee, James K.W.Williams, Ian S.info:eu-repo/semantics/openAccessreponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãoinstacron:RCAAP2024-01-03T18:43:55Zoai:dspace.uevora.pt:10174/5440Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T01:00:19.306572Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informaçãofalse |
dc.title.none.fl_str_mv |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
title |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
spellingShingle |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology Pereira, M. Francisco Variscan belt Wrench tectonics Timing of deformation Basin instability Ossa-Morena Zone South Portuguese Zone |
title_short |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
title_full |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
title_fullStr |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
title_full_unstemmed |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
title_sort |
Early carboniferous wrenching, exhumation of high-grade metamorphic rocks and basin instability in SW Iberia: Constraints derived from structural geology and U–Pb and 40Ar–39Ar geochronology |
author |
Pereira, M. Francisco |
author_facet |
Pereira, M. Francisco Chichorro, M. Silva, J. Brandão Ordonez-Casado, B. Lee, James K.W. Williams, Ian S. |
author_role |
author |
author2 |
Chichorro, M. Silva, J. Brandão Ordonez-Casado, B. Lee, James K.W. Williams, Ian S. |
author2_role |
author author author author author |
dc.contributor.author.fl_str_mv |
Pereira, M. Francisco Chichorro, M. Silva, J. Brandão Ordonez-Casado, B. Lee, James K.W. Williams, Ian S. |
dc.subject.por.fl_str_mv |
Variscan belt Wrench tectonics Timing of deformation Basin instability Ossa-Morena Zone South Portuguese Zone |
topic |
Variscan belt Wrench tectonics Timing of deformation Basin instability Ossa-Morena Zone South Portuguese Zone |
description |
New U–Pb and 40Ar–39Ar geochronology and structural data from high- tomedium grade metamorphic shear zones of the Ossa-Morena Zone, and structural data from Early Carboniferous basins (Ossa-Morena Zone and South-Portuguese Zone), place additional constraints on the Variscan tectonics in SW Iberia. A zircon U–Pb age of 465±14Ma (Middle Ordovician) measured on migmatite from the Coimbra–Cordoba shear zone is interpreted as the age of protolith crystallization. This age determination revises the information contained in the geological map of Portugal, in which these rocks were considered to be Proterozoic in age. This paper describes the evolution of Variscan wrench tectonics related to the development of shear zones, exhumation of deep crustal rocks and emplacement of magma in the Ossa-Morena Zone basement. In the Coimbra–Cordoba shear zone (transpressional), migmatites were rapidly exhumed from a depth of 42.5km to 16.6km over a period of ca. 10Ma in the Viséan (ca. 340–330Ma), indicating oblique slip exhumation rates of 8.5 to 10.6mm/yr (Campo Maior migmatites) and 3.2mm/yr (Ouguela gneisses) respectively. In the Évora Massif, the gneisses of the Boa Fé shear zone (transtensional) were exhumed from 18.5 to 7.4km depth in the period ca. 344–334Ma (Viséan), with exhumation oblique slip rates of 2.8 to 4.2mm/yr. At the same time, the Early Carboniferous basins of SW Iberia were filled by turbidites and olistoliths, composed mostly of Devonian rocks. The presence of olistoliths indicates significant tectonic instability during sedimen- tation with large-scale mass movement, probably in the form of gravity slides. Deformation and metamor- phism dated at 356±12Ma, 321±13Ma and 322±29Ma respectively suggests that Variscan wrench movements were active in SW Iberia during the Early Carboniferous for a period of at least 35Ma. |
publishDate |
2012 |
dc.date.none.fl_str_mv |
2012-11-12T11:46:37Z 2012-11-12 2012-01-01T00:00:00Z |
dc.type.status.fl_str_mv |
info:eu-repo/semantics/publishedVersion |
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
http://hdl.handle.net/10174/5440 http://hdl.handle.net/10174/5440 |
url |
http://hdl.handle.net/10174/5440 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
558-559 Tectonophysics mpereira@uevora.pt nd nd nd nd nd 250 |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.publisher.none.fl_str_mv |
Elsevier |
publisher.none.fl_str_mv |
Elsevier |
dc.source.none.fl_str_mv |
reponame:Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) instname:Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação instacron:RCAAP |
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Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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RCAAP |
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RCAAP |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
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Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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1799136485995184128 |