Paleohydrological changes during the last deglaciation in Northern Brazil

Jacob, Jérémy; Huang, Yongsong; Disnar, Jean-Robert; Sifeddine, Abdelfettah; Boussafir, Mohammed; Albuquerque, Ana Luíza Spadano; Turcq, Bruno

doi:10.1016/j.quascirev.2006.12.004

Cited by 57 publications

(45 citation statements)

References 51 publications

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“…Toledo et al (2007b) also reported the occurrence of higher temperatures in the Holocene (between 26 and 27.5°C) than in the LGM (approximately 25.5°C). According to some authors (e.g., LEDRU et al, 2005;JACOB et al, 2007;SYLVESTRE, 2009), moisture conditions in South America were higher in the LGM than in the Holocene. These humid conditions are attributed to the intensification and/or a southern shift of the Intertropical Convergence Zone (ITCZ) across northern Brazil (JACOB et al, 2007).…”

Section: Past Oceanographic Conditionsmentioning

confidence: 99%

“…According to some authors (e.g., LEDRU et al, 2005;JACOB et al, 2007;SYLVESTRE, 2009), moisture conditions in South America were higher in the LGM than in the Holocene. These humid conditions are attributed to the intensification and/or a southern shift of the Intertropical Convergence Zone (ITCZ) across northern Brazil (JACOB et al, 2007). Higher moisture rates were also reported by Ledru et al (2005) for southern Brazil, probably reflecting a displacement of the circum-polar vortex toward the equator.…”

Section: Past Oceanographic Conditionsmentioning

confidence: 99%

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Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic

et al. 2010

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A B S T R A C TChanges in the Brazilian continental margin's 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. R E S U M OMudanças 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.

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Section: Past Oceanographic Conditionsmentioning

confidence: 99%

Section: Past Oceanographic Conditionsmentioning

confidence: 99%

Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic

et al. 2010

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“…The head capsules of their exuviae frequently remain in the sediment if there are adequate conditions for preservation. The taxonomic identification of these structures in the sediment cores of the lake and its comparison with recent chironomid species can be of relevance for reconstruction of paleoenvironmental conditions Quinlan and Smol (2001), since sediment cores of Lake Caçó were collected (Jacob et al, 2007a;Jacob et al, 2007b).…”

Section: Mean Density Precipitationmentioning

confidence: 99%

Benthic macroinvertebrates of a tropical lake: Lake Caçó, MA, Brazil

et al. 2010

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Benthic communities are highly relevant in the study of aquatic ecosystems, both for their role in the functioning of the ecosystem and also as markers or indicators of paleo-conditions. Their distribution, as in other communities, is conditioned by abiotic and biotic factors and to their interactions, which determine the structure of the community that is established. The aim of this study was to determine the taxonomic composition, abundance and spatial distribution of the benthic community, by collecting at 20 sampling sites in Caçó Lake (State of Maranhão, Brazil). Seasonal variation in these community parameters was analysed and related to the seasonal displacement of the Intertropical Convergence Zone. The results indicated that changes occur in the taxa richness, diversity and density of the benthic species of this lake that are mainly related to seasonality. All those parameters were higher in the dry than in the rainy period. The family Chironomidae (Diptera, Insecta) was the most important component of the community, representing approximately 50% of the total benthic fauna of the lake. The identification of the Chironomidae currently occurring in Lake Caçó is relevant, even at the genus level, considering the fact that this group produces fossilizing remains and could perhaps be good paleolimnological and paleoclimatic tracers that could be used to make inferences on past lake and climate conditions. Keywords: benthic community, Chironomidae, Lake Caçó, tropical Limnology, macroinvertebrates. Macroinvertebrados bentônicos de um lago tropical: lago Caço, MA, Brasil ResumoAs comunidades bentônicas são relevantes nos ecossistemas aquáticos devido ao seu papel no seu funcionamento e também como marcadores ou indicadores de paleocondições. Sua distribuição, similarmente à de outras comunidades, é condicionada por fatores abióticos e bióticos e pela interação entre eles, determinando a estrutura da comunidade que se estabelecerá. O objetivo do presente trabalho foi determinar a composição taxonômica, a abundância e a distribuição espacial da comunidade bentônica, amostrando-se em 20 pontos na lagoa do Caçó (Estado do Maranhão, Brasil). As variações sazonais nas características desta comunidade foram analisadas e relacionadas ao deslocamento sazonal da Zona de Convergência Intertropical. Os resultados indicaram que ocorrem mudanças na riqueza de taxons, diversidade e densidade da comunidade bentônica deste lago que são principalmente relacionadas à sazonalidade. Todas as variáveis analisadas foram maiores no período seco do que no chuvoso. Os organismos pertencentes à família Chironomidae (Diptera, Insecta) foram os mais importantes componentes da comunidade, representando aproximadamente 50% do total da fauna. A identificação dos Chironomidae atualmente presentes no Lago Caçó, mesmo em nível de gênero, é relevante, considerando-se o fato de que as larvas deste grupo produzem remanescentes fósseis que podem ser bons traçadores paleolimnológicos e paleoclimáticos, podendo ser utilizados para fazer inf...

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“…These compounds then emerged as potential paleoclimatic and paleohydrological proxies (Andersen et al, 2001;Sauer et al, 2001;Yang and Huang, 2003;Huang et al, 2004;Sachse et al, 2004;Liu and Huang, 2005;Jacob et al, 2007;Makou et al, 2007;Xia et al, 2008;Xie et al, 2000Xie et al, , 2004.…”

Section: Introductionmentioning

confidence: 99%

Retraction: Paleoclimatic implications of the hydrogen isotopic composition of terrigenous n-alkanes from Lake Yamzho, southern Tibetan Plateau

Zhonghuan

Mügler

et al. 2009

Geochem. J.

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The hydrogen isotopic composition (δD) of leaf water used for biosynthesis of n-alkanes can be modified by climate. Therefore, the δD can be considered as potential paleoclimatic proxy to explore. We compared measured δD values of alkanes (n-C 25 to n-C 31 ) extracted from a short sediment profile spanning the past 50 years with a 7-year resolution from Lake Yamzho, southern Tibetan Plateau. Climatic control was reconstructed using meteorological records of the nearby Langkazi and Lhasa weather stations. We found that the δD values of the n-alkanes correlated with the mean annual air temperature and significantly correlated with the mean growing season air temperature. On the other hand, the δD values show poor correlations with both rainfall amount and relative humidity. These results indicate that stable isotope composition of n-alkanes could be an excellent proxy for paleotemperature reconstruction.

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Paleohydrological changes during the last deglaciation in Northern Brazil

Cited by 57 publications

References 51 publications

Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic

Paleoproductivity changes during the Late Quaternary in the southeastern Brazilian upper continental margin of the Southwestern Atlantic

Benthic macroinvertebrates of a tropical lake: Lake Caçó, MA, Brazil

Retraction: Paleoclimatic implications of the hydrogen isotopic composition of terrigenous n-alkanes from Lake Yamzho, southern Tibetan Plateau

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