Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil
Autor(a) principal: | |
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Data de Publicação: | 2016 |
Outros Autores: | |
Tipo de documento: | Artigo |
Idioma: | por |
Título da fonte: | Anuário do Instituto de Geociências (Online) |
Texto Completo: | https://revistas.ufrj.br/index.php/aigeo/article/view/6994 |
Resumo: | The nature of sedimentation and sediment accumulation rates in Sepetiba Bay, Brazil were interpreted from grainsize patterns, natural radiochemical distributions and seismic stratigraphy. The grain-size analyses showed progressive upward fining of sediment in cores, and a higher percentage of clay in surficial deposits in 1996 than observed during a previous spatial survey in the 1970s. Based on 210Pb geochronology, accumulation rates range from 0.37 cm yr-1 to 2.0 cm yr-1 for the last hundred years. In contrast, seismic stratigraphy indicates a range from 0.01 to 0.17 cm yr-1 over the last 7000 years. Particularly high accumulation rates are found in the northeast part of the bay, and, as a consequence of these high rates, the shoreline in the northern part of the bay prograded approximately 400 m in the last 100 years. An apparent increase in accumulation rates and a tendency for deposits to fine upward over the last ~ 100 years are attributed to human disturbance and soil erosion inland, which have been accelerated with economic development since the late 1970s. |
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Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, BrazilSedimentação Costeira em um Sistema de Ilha-de-Barreira Tropical Durante o Último Século na Baía de Sepetiba210Pb geochronology; Sedimentation; Sepetiba Bay; Seismic stratigraphyGeocronologia do 210Pb; Sedimentação; Baía de Sepetiba; Estratigrafia sísmica.The nature of sedimentation and sediment accumulation rates in Sepetiba Bay, Brazil were interpreted from grainsize patterns, natural radiochemical distributions and seismic stratigraphy. The grain-size analyses showed progressive upward fining of sediment in cores, and a higher percentage of clay in surficial deposits in 1996 than observed during a previous spatial survey in the 1970s. Based on 210Pb geochronology, accumulation rates range from 0.37 cm yr-1 to 2.0 cm yr-1 for the last hundred years. In contrast, seismic stratigraphy indicates a range from 0.01 to 0.17 cm yr-1 over the last 7000 years. Particularly high accumulation rates are found in the northeast part of the bay, and, as a consequence of these high rates, the shoreline in the northern part of the bay prograded approximately 400 m in the last 100 years. An apparent increase in accumulation rates and a tendency for deposits to fine upward over the last ~ 100 years are attributed to human disturbance and soil erosion inland, which have been accelerated with economic development since the late 1970s.A natureza da sedimentação e as taxas de sedimentação na Baía de Sepetiba, Brasil, foram interpretadas a partir dos padrões granulométricos, distribuição radiométrica natural e estratigrafia sísmica. A análise granulométrica mostrou uma diminuição progressiva no tamanho dos grãos nos testemunhos e uma alta porcentagem de argila em depósitos superficiais em 1996, do que a observada durante um levantamento anterior nos anos 70. Baseado em datações por 210Pb, as taxas de acumulação variam de 0.37 cm/ano a 2.0 cm/ano, para os últimos 100 anos. Em contrapartida, a estratigrafia sísmica indica uma variação de 0.01 a 0.17 cm/ano ao longo dos últimos 7000 anos. Taxas de acumulação particularmente altas são encontradas na parte nordeste da baía e, em consequência destas altas taxas, a linha de costa na parte norte da baía progradou aproximadamente 400 m nos últimos 100 anos. Um aumento aparente nas taxas de acumulação e uma tendência à deposição de sedimentos finos ao longo dos últimos 100 anos, são atribuídos à ação.Universidade Federal do Rio de Janeiro2016-06-23info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionapplication/pdfhttps://revistas.ufrj.br/index.php/aigeo/article/view/699410.11137/2016_2_05_14Anuário do Instituto de Geociências; Vol 39, No 2 (2016); 5-14Anuário do Instituto de Geociências; Vol 39, No 2 (2016); 5-141982-39080101-9759reponame:Anuário do Instituto de Geociências (Online)instname:Universidade Federal do Rio de Janeiro (UFRJ)instacron:UFRJporhttps://revistas.ufrj.br/index.php/aigeo/article/view/6994/5561Copyright (c) 2016 Anuário do Instituto de Geociênciashttp://creativecommons.org/licenses/by/4.0info:eu-repo/semantics/openAccessBorges, Heloisa VargasNittrouer, Charles A.2017-01-23T22:48:34Zoai:www.revistas.ufrj.br:article/6994Revistahttps://revistas.ufrj.br/index.php/aigeo/indexPUBhttps://revistas.ufrj.br/index.php/aigeo/oaianuario@igeo.ufrj.br||1982-39080101-9759opendoar:2017-01-23T22:48:34Anuário do Instituto de Geociências (Online) - Universidade Federal do Rio de Janeiro (UFRJ)false |
dc.title.none.fl_str_mv |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil Sedimentação Costeira em um Sistema de Ilha-de-Barreira Tropical Durante o Último Século na Baía de Sepetiba |
title |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil |
spellingShingle |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil Borges, Heloisa Vargas 210Pb geochronology; Sedimentation; Sepetiba Bay; Seismic stratigraphy Geocronologia do 210Pb; Sedimentação; Baía de Sepetiba; Estratigrafia sísmica. |
title_short |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil |
title_full |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil |
title_fullStr |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil |
title_full_unstemmed |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil |
title_sort |
Coastal Sedimentation in a Tropical Barrier-Island System During the Past Century in Sepetiba Bay, Brazil |
author |
Borges, Heloisa Vargas |
author_facet |
Borges, Heloisa Vargas Nittrouer, Charles A. |
author_role |
author |
author2 |
Nittrouer, Charles A. |
author2_role |
author |
dc.contributor.author.fl_str_mv |
Borges, Heloisa Vargas Nittrouer, Charles A. |
dc.subject.por.fl_str_mv |
210Pb geochronology; Sedimentation; Sepetiba Bay; Seismic stratigraphy Geocronologia do 210Pb; Sedimentação; Baía de Sepetiba; Estratigrafia sísmica. |
topic |
210Pb geochronology; Sedimentation; Sepetiba Bay; Seismic stratigraphy Geocronologia do 210Pb; Sedimentação; Baía de Sepetiba; Estratigrafia sísmica. |
description |
The nature of sedimentation and sediment accumulation rates in Sepetiba Bay, Brazil were interpreted from grainsize patterns, natural radiochemical distributions and seismic stratigraphy. The grain-size analyses showed progressive upward fining of sediment in cores, and a higher percentage of clay in surficial deposits in 1996 than observed during a previous spatial survey in the 1970s. Based on 210Pb geochronology, accumulation rates range from 0.37 cm yr-1 to 2.0 cm yr-1 for the last hundred years. In contrast, seismic stratigraphy indicates a range from 0.01 to 0.17 cm yr-1 over the last 7000 years. Particularly high accumulation rates are found in the northeast part of the bay, and, as a consequence of these high rates, the shoreline in the northern part of the bay prograded approximately 400 m in the last 100 years. An apparent increase in accumulation rates and a tendency for deposits to fine upward over the last ~ 100 years are attributed to human disturbance and soil erosion inland, which have been accelerated with economic development since the late 1970s. |
publishDate |
2016 |
dc.date.none.fl_str_mv |
2016-06-23 |
dc.type.none.fl_str_mv |
|
dc.type.driver.fl_str_mv |
info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion |
format |
article |
status_str |
publishedVersion |
dc.identifier.uri.fl_str_mv |
https://revistas.ufrj.br/index.php/aigeo/article/view/6994 10.11137/2016_2_05_14 |
url |
https://revistas.ufrj.br/index.php/aigeo/article/view/6994 |
identifier_str_mv |
10.11137/2016_2_05_14 |
dc.language.iso.fl_str_mv |
por |
language |
por |
dc.relation.none.fl_str_mv |
https://revistas.ufrj.br/index.php/aigeo/article/view/6994/5561 |
dc.rights.driver.fl_str_mv |
Copyright (c) 2016 Anuário do Instituto de Geociências http://creativecommons.org/licenses/by/4.0 info:eu-repo/semantics/openAccess |
rights_invalid_str_mv |
Copyright (c) 2016 Anuário do Instituto de Geociências http://creativecommons.org/licenses/by/4.0 |
eu_rights_str_mv |
openAccess |
dc.format.none.fl_str_mv |
application/pdf |
dc.publisher.none.fl_str_mv |
Universidade Federal do Rio de Janeiro |
publisher.none.fl_str_mv |
Universidade Federal do Rio de Janeiro |
dc.source.none.fl_str_mv |
Anuário do Instituto de Geociências; Vol 39, No 2 (2016); 5-14 Anuário do Instituto de Geociências; Vol 39, No 2 (2016); 5-14 1982-3908 0101-9759 reponame:Anuário do Instituto de Geociências (Online) instname:Universidade Federal do Rio de Janeiro (UFRJ) instacron:UFRJ |
instname_str |
Universidade Federal do Rio de Janeiro (UFRJ) |
instacron_str |
UFRJ |
institution |
UFRJ |
reponame_str |
Anuário do Instituto de Geociências (Online) |
collection |
Anuário do Instituto de Geociências (Online) |
repository.name.fl_str_mv |
Anuário do Instituto de Geociências (Online) - Universidade Federal do Rio de Janeiro (UFRJ) |
repository.mail.fl_str_mv |
anuario@igeo.ufrj.br|| |
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1797053536965492736 |