Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic
Changes in the Brazilian continental margins oceanic productivity and circulation over the last 27,000 years were reconstructed based on sedimentological and microfaunal analyses. Our results suggest that oceanic paleoproductivity and the supply of terrigenous sediments to the Brazilian continental...
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| Language: | English |
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Universidade de São Paulo
2010-01-01
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| Series: | Brazilian Journal of Oceanography |
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| Online Access: | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592010000500004 |
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| author | Renata Hanae Nagai Silvia Helena de Mello e Sousa Rafael André Lourenço Márcia Caruso Bícego Michel Michaelovitch de Mahiques |
| author_facet | Renata Hanae Nagai Silvia Helena de Mello e Sousa Rafael André Lourenço Márcia Caruso Bícego Michel Michaelovitch de Mahiques |
| author_sort | Renata Hanae Nagai |
| collection | DOAJ |
| description | Changes in the Brazilian continental margins oceanic productivity and circulation over the last 27,000 years were reconstructed based on sedimentological and microfaunal analyses. Our results suggest that oceanic paleoproductivity and the supply of terrigenous sediments to the Brazilian continental margin were higher during the Last Glacial Maximum (LGM) than during the Holocene. These changes may have been primarily influenced by significant sea level fluctuations that have occurred since the late Pleistocene. During the LGM, the lower sea level, higher productivity and lower sea-surface paleotemperatures may have been the result of the offshore displacement of the main flow of the Brazil Current. However, during the Holocene, the warm waters of the Brazil Current were displaced toward the coast. This displacement contributed to the increase in water temperature and prevented an increase in oceanic productivity. The decrease in terrigenous supply since the LGM could be related to the increase of the extension of the continental shelf and/or drier climatic conditions.<br>Mudanças na produtividade e circulação oceânica da margem continental Brasileira foram reconstituídas a partir de análises sedimentológicas e microfaunísticas realizadas em sedimentos de um testemunho representativo dos últimos 27 000 anos. Nossos dados sugerem maior produtividade oceânica e suprimento de sedimento terrígeno na área de estudo no Último Máximo Glacial (UMG) do que no Holoceno. Estas mudanças foram principalmente influenciadas por flutuações do nível relativo do mar. Durante o UMG, num cenário de nível relativo do mar mais baixo, a maior produtividade oceânica e menor temperatura da superfície do mar, podem ter sido produtos do deslocamento para o largo da Corrente do Brasil. No Holoceno, o deslocamento para a costa das águas quentes da Corrente do Brasil contribuiu para o aumento na temperatura da água e menor produtividade oceânica. A diminuição do aporte de sedimentos terrígenos desde o UMG pode estar relacionado ao aumento da extensão da plataforma continental e/ou a condições climáticas mais secas no continente. |
| first_indexed | 2024-12-22T05:58:22Z |
| format | Article |
| id | doaj.art-dee78b6063e84ad49d4da126681a5563 |
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| issn | 1679-8759 1982-436X |
| language | English |
| last_indexed | 2024-12-22T05:58:22Z |
| publishDate | 2010-01-01 |
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| series | Brazilian Journal of Oceanography |
| spelling | doaj.art-dee78b6063e84ad49d4da126681a55632022-12-21T18:36:37ZengUniversidade de São PauloBrazilian Journal of Oceanography1679-87591982-436X2010-01-0158spe1314110.1590/S1679-87592010000500004Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern AtlanticRenata Hanae NagaiSilvia Helena de Mello e SousaRafael André LourençoMárcia Caruso BícegoMichel Michaelovitch de MahiquesChanges in the Brazilian continental margins oceanic productivity and circulation over the last 27,000 years were reconstructed based on sedimentological and microfaunal analyses. Our results suggest that oceanic paleoproductivity and the supply of terrigenous sediments to the Brazilian continental margin were higher during the Last Glacial Maximum (LGM) than during the Holocene. These changes may have been primarily influenced by significant sea level fluctuations that have occurred since the late Pleistocene. During the LGM, the lower sea level, higher productivity and lower sea-surface paleotemperatures may have been the result of the offshore displacement of the main flow of the Brazil Current. However, during the Holocene, the warm waters of the Brazil Current were displaced toward the coast. This displacement contributed to the increase in water temperature and prevented an increase in oceanic productivity. The decrease in terrigenous supply since the LGM could be related to the increase of the extension of the continental shelf and/or drier climatic conditions.<br>Mudanças na produtividade e circulação oceânica da margem continental Brasileira foram reconstituídas a partir de análises sedimentológicas e microfaunísticas realizadas em sedimentos de um testemunho representativo dos últimos 27 000 anos. Nossos dados sugerem maior produtividade oceânica e suprimento de sedimento terrígeno na área de estudo no Último Máximo Glacial (UMG) do que no Holoceno. Estas mudanças foram principalmente influenciadas por flutuações do nível relativo do mar. Durante o UMG, num cenário de nível relativo do mar mais baixo, a maior produtividade oceânica e menor temperatura da superfície do mar, podem ter sido produtos do deslocamento para o largo da Corrente do Brasil. No Holoceno, o deslocamento para a costa das águas quentes da Corrente do Brasil contribuiu para o aumento na temperatura da água e menor produtividade oceânica. A diminuição do aporte de sedimentos terrígenos desde o UMG pode estar relacionado ao aumento da extensão da plataforma continental e/ou a condições climáticas mais secas no continente.http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592010000500004ForaminiferosCorrente do BrasilQuaternário TardioAtlântico SudoesteForaminiferaBrazil CurrentLate QuaternarySouthwestern Atlantic |
| spellingShingle | Renata Hanae Nagai Silvia Helena de Mello e Sousa Rafael André Lourenço Márcia Caruso Bícego Michel Michaelovitch de Mahiques Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic Brazilian Journal of Oceanography Foraminiferos Corrente do Brasil Quaternário Tardio Atlântico Sudoeste Foraminifera Brazil Current Late Quaternary Southwestern Atlantic |
| title | Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic |
| title_full | Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic |
| title_fullStr | Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic |
| title_full_unstemmed | Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic |
| title_short | Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic |
| title_sort | paleoproductivity changes during the late quaternary in the southeastern brazilian upper continental margin of the southwestern atlantic |
| topic | Foraminiferos Corrente do Brasil Quaternário Tardio Atlântico Sudoeste Foraminifera Brazil Current Late Quaternary Southwestern Atlantic |
| url | http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1679-87592010000500004 |
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