Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance
Autor(a) principal: | |
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Data de Publicação: | 2010 |
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/10174/2213 |
Resumo: | Abstract At SW Iberia, the boundary between Iberian and South-Portuguese Terranes is traced by a suture recording the closure of Rheic and related oceans through N-NE subduction. The western segment of the suture comprises imbrications of Iberian Terrane Relative Autochthon (Neoproterozoic - Lower Palaeozoic) and Allochthonous Complexes. The Iberian Terrane Relative Autochthon is topped by Lower-Middle Devonian metasediments and an unconformable cover of Lower Carboniferous (calc-alkaline) Volcano-sedimentary Complexes, both preserving evidence of very-low grade metamorphism. The Allochthonous Complexes include disrupted slivers of eclogite (ca. 370 Ma), klippen and slices of an internal ophiolite sequence (IOMZOS), a basal tectonic mélange (Moura Phyllonitic Complex) and an external ophiolite (Beja-Acebuches Complex, BAOC). A large layered gabbroic sequence (LGS), part of the Beja Igneous Complex, intruded (ca. 350-340 Ma) the SW suture domains. The IOMZOS represent obducted remnants of the Rheic Ocean, for which the available SHRIMP U-Pb data indicate and age of 4795.1 Ma; this ocean, separating Iberia from a promontory of Gondwana and Avalonia (now represented by the South-Portuguese Terrane), opened near the Cambrian-Ordovician transition through a “rift-jump” from an intra-cratonic setting (within the Iberian Terrane) to an intra-oceanic rifting. The BAOC displays geochemical features compatible with derivation from a [Lower-Middle Devonian (?); TDM (Sm-Nd) 380-440 Ma] short-lived back-arc basin. The Variscan ophiolite belts preserved along the SW Variscides were emplaced by antithetic obduction in two stages, both with shearing sense to N-NE. The first stage involved IOMZOS cold obduction, exhumated HP-rocks (ca. 370 Ma) and created a foreland bulge towards the Iberian Terrane SW flank; this mechanism controlled the development of the volcanic related carbonate shelves and the contemporaneous (NE) Terena flysch trough. The second stage corresponds to BAOC hot obduction, carrying the IOMZOS klippen in piggy-back style and affecting the southern margin of LGS at ca. 350-340 Ma. |
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Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significanceOphiolite beltsGeodynamic evolutionSw Iberian VariscidesAbstract At SW Iberia, the boundary between Iberian and South-Portuguese Terranes is traced by a suture recording the closure of Rheic and related oceans through N-NE subduction. The western segment of the suture comprises imbrications of Iberian Terrane Relative Autochthon (Neoproterozoic - Lower Palaeozoic) and Allochthonous Complexes. The Iberian Terrane Relative Autochthon is topped by Lower-Middle Devonian metasediments and an unconformable cover of Lower Carboniferous (calc-alkaline) Volcano-sedimentary Complexes, both preserving evidence of very-low grade metamorphism. The Allochthonous Complexes include disrupted slivers of eclogite (ca. 370 Ma), klippen and slices of an internal ophiolite sequence (IOMZOS), a basal tectonic mélange (Moura Phyllonitic Complex) and an external ophiolite (Beja-Acebuches Complex, BAOC). A large layered gabbroic sequence (LGS), part of the Beja Igneous Complex, intruded (ca. 350-340 Ma) the SW suture domains. The IOMZOS represent obducted remnants of the Rheic Ocean, for which the available SHRIMP U-Pb data indicate and age of 4795.1 Ma; this ocean, separating Iberia from a promontory of Gondwana and Avalonia (now represented by the South-Portuguese Terrane), opened near the Cambrian-Ordovician transition through a “rift-jump” from an intra-cratonic setting (within the Iberian Terrane) to an intra-oceanic rifting. The BAOC displays geochemical features compatible with derivation from a [Lower-Middle Devonian (?); TDM (Sm-Nd) 380-440 Ma] short-lived back-arc basin. The Variscan ophiolite belts preserved along the SW Variscides were emplaced by antithetic obduction in two stages, both with shearing sense to N-NE. The first stage involved IOMZOS cold obduction, exhumated HP-rocks (ca. 370 Ma) and created a foreland bulge towards the Iberian Terrane SW flank; this mechanism controlled the development of the volcanic related carbonate shelves and the contemporaneous (NE) Terena flysch trough. The second stage corresponds to BAOC hot obduction, carrying the IOMZOS klippen in piggy-back style and affecting the southern margin of LGS at ca. 350-340 Ma.Elsevier2010-11-19T11:01:18Z2010-11-192010-01-01T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/article124435 bytesapplication/pdfhttp://hdl.handle.net/10174/2213http://hdl.handle.net/10174/2213eng408-425Gondwana Research17livreGEOndndndaaraujo@uevora.ptndndndndnd395Ribeiro, A.Munhá, J.Fonseca, P. E.Araújo, A.Pedro, JorgeMateus, A.Tassinari, C.Machado, G.Jesus, A.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:RCAAP2024-01-03T18:38:19Zoai:dspace.uevora.pt:10174/2213Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T00:57:53.865776Repositório 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 |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
title |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
spellingShingle |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance Ribeiro, A. Ophiolite belts Geodynamic evolution Sw Iberian Variscides |
title_short |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
title_full |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
title_fullStr |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
title_full_unstemmed |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
title_sort |
Variscan ophiolite belts in the Ossa-Morena Zone (Southwest Iberia): Geological characterization and geodynamic significance |
author |
Ribeiro, A. |
author_facet |
Ribeiro, A. Munhá, J. Fonseca, P. E. Araújo, A. Pedro, Jorge Mateus, A. Tassinari, C. Machado, G. Jesus, A. |
author_role |
author |
author2 |
Munhá, J. Fonseca, P. E. Araújo, A. Pedro, Jorge Mateus, A. Tassinari, C. Machado, G. Jesus, A. |
author2_role |
author author author author author author author author |
dc.contributor.author.fl_str_mv |
Ribeiro, A. Munhá, J. Fonseca, P. E. Araújo, A. Pedro, Jorge Mateus, A. Tassinari, C. Machado, G. Jesus, A. |
dc.subject.por.fl_str_mv |
Ophiolite belts Geodynamic evolution Sw Iberian Variscides |
topic |
Ophiolite belts Geodynamic evolution Sw Iberian Variscides |
description |
Abstract At SW Iberia, the boundary between Iberian and South-Portuguese Terranes is traced by a suture recording the closure of Rheic and related oceans through N-NE subduction. The western segment of the suture comprises imbrications of Iberian Terrane Relative Autochthon (Neoproterozoic - Lower Palaeozoic) and Allochthonous Complexes. The Iberian Terrane Relative Autochthon is topped by Lower-Middle Devonian metasediments and an unconformable cover of Lower Carboniferous (calc-alkaline) Volcano-sedimentary Complexes, both preserving evidence of very-low grade metamorphism. The Allochthonous Complexes include disrupted slivers of eclogite (ca. 370 Ma), klippen and slices of an internal ophiolite sequence (IOMZOS), a basal tectonic mélange (Moura Phyllonitic Complex) and an external ophiolite (Beja-Acebuches Complex, BAOC). A large layered gabbroic sequence (LGS), part of the Beja Igneous Complex, intruded (ca. 350-340 Ma) the SW suture domains. The IOMZOS represent obducted remnants of the Rheic Ocean, for which the available SHRIMP U-Pb data indicate and age of 4795.1 Ma; this ocean, separating Iberia from a promontory of Gondwana and Avalonia (now represented by the South-Portuguese Terrane), opened near the Cambrian-Ordovician transition through a “rift-jump” from an intra-cratonic setting (within the Iberian Terrane) to an intra-oceanic rifting. The BAOC displays geochemical features compatible with derivation from a [Lower-Middle Devonian (?); TDM (Sm-Nd) 380-440 Ma] short-lived back-arc basin. The Variscan ophiolite belts preserved along the SW Variscides were emplaced by antithetic obduction in two stages, both with shearing sense to N-NE. The first stage involved IOMZOS cold obduction, exhumated HP-rocks (ca. 370 Ma) and created a foreland bulge towards the Iberian Terrane SW flank; this mechanism controlled the development of the volcanic related carbonate shelves and the contemporaneous (NE) Terena flysch trough. The second stage corresponds to BAOC hot obduction, carrying the IOMZOS klippen in piggy-back style and affecting the southern margin of LGS at ca. 350-340 Ma. |
publishDate |
2010 |
dc.date.none.fl_str_mv |
2010-11-19T11:01:18Z 2010-11-19 2010-01-01T00:00:00Z |
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/10174/2213 http://hdl.handle.net/10174/2213 |
url |
http://hdl.handle.net/10174/2213 |
dc.language.iso.fl_str_mv |
eng |
language |
eng |
dc.relation.none.fl_str_mv |
408-425 Gondwana Research 17 livre GEO nd nd nd aaraujo@uevora.pt nd nd nd nd nd 395 |
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info:eu-repo/semantics/openAccess |
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openAccess |
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124435 bytes application/pdf |
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Elsevier |
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Elsevier |
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