Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais
Autor(a) principal: | |
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Data de Publicação: | 2010 |
Outros Autores: | , |
Tipo de documento: | Artigo |
Idioma: | fra |
Título da fonte: | Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
Texto Completo: | http://hdl.handle.net/10362/4668 |
Resumo: | In Portugal, Carixian is generally represented by alternative layers of marly limestones characterized by nodule and lumpy levels. These layers are particularly developped [show preferential development] on passage areas to a sedimentary basin, particularly along the slope of tilted blocks between the Meseta and Berlenga's horst. This facies is included in the range of the «nodular limestone» and of the «ammonitico-rosso». Limestones are radiolaria micrites with fragments of pelagic organisms (ammonoids, thin shelled gastropods). These layers can be affected by intensive bioturbation (Brenha) which is responsible for dismantlement, specially where the initial thickness does not exceed a few centimetres. This process can lead to the isolation of residual nodules (Brenha, São Pedro de Muel, Peniche) which can be mobilised by massive sliding (Peniche). The isolated elements, shell fragments or residual nodules, can also be incrustated, thus developing oncolitic cryptalgal structures. At Brenha the lump structure developed progressively into a sequence overlapping the normal sedimentary one (thick limestone beds alternating with bituminous shales). Cryptalgal structures correspond to rather unstable environment conditions on mobile margins. These structures are known in deep pelagic sediments corresponding to well defined events of the geodynamic evolution (end of the initial rifting). Cryptalgal accretions disappear towards the sedimentary basin, and the nodular levels are less important. In the articulation areas with the Tomar platform, small mounds and cupules (Alcabideque) developed within the alternating marly-limestone levels. They represent the so called «mud mounds» of metric dimensions. The upper part of these «mud mounds» is hardened, showing track remains and supporting some brachiopods and pectinids. Hence the lumpy facies of Portugal is included among the range of sedimentaty environments and can be used as «geodynamic tracer». |
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Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugaisLumpy faciesCryptalgal structuresPaleoenvironmentGeodynamic tracerCarixianPortugalIn Portugal, Carixian is generally represented by alternative layers of marly limestones characterized by nodule and lumpy levels. These layers are particularly developped [show preferential development] on passage areas to a sedimentary basin, particularly along the slope of tilted blocks between the Meseta and Berlenga's horst. This facies is included in the range of the «nodular limestone» and of the «ammonitico-rosso». Limestones are radiolaria micrites with fragments of pelagic organisms (ammonoids, thin shelled gastropods). These layers can be affected by intensive bioturbation (Brenha) which is responsible for dismantlement, specially where the initial thickness does not exceed a few centimetres. This process can lead to the isolation of residual nodules (Brenha, São Pedro de Muel, Peniche) which can be mobilised by massive sliding (Peniche). The isolated elements, shell fragments or residual nodules, can also be incrustated, thus developing oncolitic cryptalgal structures. At Brenha the lump structure developed progressively into a sequence overlapping the normal sedimentary one (thick limestone beds alternating with bituminous shales). Cryptalgal structures correspond to rather unstable environment conditions on mobile margins. These structures are known in deep pelagic sediments corresponding to well defined events of the geodynamic evolution (end of the initial rifting). Cryptalgal accretions disappear towards the sedimentary basin, and the nodular levels are less important. In the articulation areas with the Tomar platform, small mounds and cupules (Alcabideque) developed within the alternating marly-limestone levels. They represent the so called «mud mounds» of metric dimensions. The upper part of these «mud mounds» is hardened, showing track remains and supporting some brachiopods and pectinids. Hence the lumpy facies of Portugal is included among the range of sedimentaty environments and can be used as «geodynamic tracer».RUNElmi, S.Rocha, R. B.Mouterde, R.2010-12-28T14:55:12Z2010-12-282010-12-28T00:00:00Zinfo:eu-repo/semantics/publishedVersioninfo:eu-repo/semantics/articleapplication/pdfhttp://hdl.handle.net/10362/4668frainfo: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:RCAAP2024-03-11T03:31:35Zoai:run.unl.pt:10362/4668Portal AgregadorONGhttps://www.rcaap.pt/oai/openaireopendoar:71602024-03-20T03:14:45.954687Repositório 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 |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
title |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
spellingShingle |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais Elmi, S. Lumpy facies Cryptalgal structures Paleoenvironment Geodynamic tracer Carixian Portugal |
title_short |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
title_full |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
title_fullStr |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
title_full_unstemmed |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
title_sort |
Sedimentation pelagique et encroûtements cryptalgaires: les calcaires gremeleux du Carixien portugais |
author |
Elmi, S. |
author_facet |
Elmi, S. Rocha, R. B. Mouterde, R. |
author_role |
author |
author2 |
Rocha, R. B. Mouterde, R. |
author2_role |
author author |
dc.contributor.none.fl_str_mv |
RUN |
dc.contributor.author.fl_str_mv |
Elmi, S. Rocha, R. B. Mouterde, R. |
dc.subject.por.fl_str_mv |
Lumpy facies Cryptalgal structures Paleoenvironment Geodynamic tracer Carixian Portugal |
topic |
Lumpy facies Cryptalgal structures Paleoenvironment Geodynamic tracer Carixian Portugal |
description |
In Portugal, Carixian is generally represented by alternative layers of marly limestones characterized by nodule and lumpy levels. These layers are particularly developped [show preferential development] on passage areas to a sedimentary basin, particularly along the slope of tilted blocks between the Meseta and Berlenga's horst. This facies is included in the range of the «nodular limestone» and of the «ammonitico-rosso». Limestones are radiolaria micrites with fragments of pelagic organisms (ammonoids, thin shelled gastropods). These layers can be affected by intensive bioturbation (Brenha) which is responsible for dismantlement, specially where the initial thickness does not exceed a few centimetres. This process can lead to the isolation of residual nodules (Brenha, São Pedro de Muel, Peniche) which can be mobilised by massive sliding (Peniche). The isolated elements, shell fragments or residual nodules, can also be incrustated, thus developing oncolitic cryptalgal structures. At Brenha the lump structure developed progressively into a sequence overlapping the normal sedimentary one (thick limestone beds alternating with bituminous shales). Cryptalgal structures correspond to rather unstable environment conditions on mobile margins. These structures are known in deep pelagic sediments corresponding to well defined events of the geodynamic evolution (end of the initial rifting). Cryptalgal accretions disappear towards the sedimentary basin, and the nodular levels are less important. In the articulation areas with the Tomar platform, small mounds and cupules (Alcabideque) developed within the alternating marly-limestone levels. They represent the so called «mud mounds» of metric dimensions. The upper part of these «mud mounds» is hardened, showing track remains and supporting some brachiopods and pectinids. Hence the lumpy facies of Portugal is included among the range of sedimentaty environments and can be used as «geodynamic tracer». |
publishDate |
2010 |
dc.date.none.fl_str_mv |
2010-12-28T14:55:12Z 2010-12-28 2010-12-28T00:00:00Z |
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/10362/4668 |
url |
http://hdl.handle.net/10362/4668 |
dc.language.iso.fl_str_mv |
fra |
language |
fra |
dc.rights.driver.fl_str_mv |
info:eu-repo/semantics/openAccess |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
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 |
instname_str |
Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
instacron_str |
RCAAP |
institution |
RCAAP |
reponame_str |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
collection |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) |
repository.name.fl_str_mv |
Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos) - Agência para a Sociedade do Conhecimento (UMIC) - FCT - Sociedade da Informação |
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1799137800274051072 |