OSL age determinations of Pleistocene fluvial deposits in Central Amazonia

Soares, Emílio Alberto Amaral; Tatumi, Sônia Hatsue; Riccomini, Claudio

doi:10.1590/s0001-37652010000300017

Cited by 50 publications

(64 citation statements)

References 29 publications

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“…The palaeogeographic mechanism for this vicariance event apparently involved the establishment of the current course of the lower Negro River in response to a series of neotectonic faulting events [10,47,48] (see electronic supplementary material). Supporting this molecular dating result, Soares et al [47] found evidence for an age of about 0.4 Ma for the initiation of sedimentation covering the Miocene Novo Remanso formation along the lower Negro River.…”

Section: Discussion (A) Testing the Refuge Hypothesismentioning

confidence: 99%

A palaeobiogeographic model for biotic diversification within Amazonia over the past three million years

et al. 2011

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Many hypotheses have been proposed to explain high species diversity in Amazonia, but few generalizations have emerged. In part, this has arisen from the scarcity of rigorous tests for mechanisms promoting speciation, and from major uncertainties about palaeogeographic events and their spatial and temporal associations with diversification. Here, we investigate the environmental history of Amazonia using a phylogenetic and biogeographic analysis of trumpeters (Aves: Psophia), which are represented by species in each of the vertebrate areas of endemism. Their relationships reveal an unforeseen 'complete' time-slice of Amazonian diversification over the past 3.0 Myr. We employ this temporally calibrated phylogeny to test competing palaeogeographic hypotheses. Our results are consistent with the establishment of the current Amazonian drainage system at approximately 3.0 -2.0 Ma and predict the temporal pattern of major river formation over Plio-Pleistocene times. We propose a palaeobiogeographic model for the last 3.0 Myr of Amazonian history that has implications for understanding patterns of endemism, the temporal history of Amazonian diversification and mechanisms promoting speciation. The history of Psophia, in combination with new geological evidence, provides the strongest direct evidence supporting a role for river dynamics in Amazonian diversification, and the absence of such a role for glacial climate cycles and refugia.

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Section: Discussion (A) Testing the Refuge Hypothesismentioning

confidence: 99%

A palaeobiogeographic model for biotic diversification within Amazonia over the past three million years

et al. 2011

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“…Middle Miocene strata, dated in Central Amazon outcrops, in the vicinity of Manaus, was informally designated as Novo Remanso Formation (Rozo 2004, Rozo et al 2005, Dino 2006a, b, Soares 2007, Soares et al 2010a,b, Dino et al 2012, on the assumption that Alter do Chão Formation was as old as the Cretaceous, justifying a new Cenozoic stratigraphic unit in the basin. This Cenozoic unit supports the high relief of the regions of Manacapuru, Manaus, Itacoatiara, Itapiranga and São Sebastião do Uatumã localities (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Since several glacial and interglacial stages occurred, with consequent droppings and risings of sea level, several differently-aged fluvial terraces were built up along the rivers of Brazilian Amazon and other neighboring countries (Franzinelli & Ori 1988, Rossetti et al 2005, Gonçalves Junior 2013, Carlotto et al 2008, Soares et al 2010a). In the Central Amazon area, the oldest terrace is probably represented by the Içá Formation, other known, ancient fluvial terraces of the Solimões River, informally denominated as Upper Terrace, present ages of approximately 200,000 years Before Present (BP) and are continuous and parallel to the major rivers (Soares et al 2010a, b, Gonçalves 2013, being only interrupted by tributaries like the Purus and Madeira rivers. During the Pleistocene, occurred new extinction processes because of the environmental changes deriving from several droppings and risings of sea level.…”

Section: Amazon Rivermentioning

confidence: 99%

Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

Caputo

Soares

2016

Braz. J. Geol.

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The development of the transcontinental Amazon River System involved geological events in the Andes Chain; Vaupés, Purus and Gurupá arches; sedimentary basins of the region and sea level changes. The origin and age of this river have been discussed for decades, and many ideas have been proposed, including those pertaining to it having originated in the Holocene, Pleistocene, Pliocene, Late Miocene, or even earlier times. Under this context, the geology of the sedimentary basins of northern Brazil has been analyzed from the Mesozoic time on, and some clarifications are placed on its stratigraphy. Vaupés Arch, in Colombia, was uplifted together with the Andean Mountains in the Middle Miocene time. In the Cenozoic Era, the Purus Arch has not blocked this drainage system westward to marine basins of Western South America or eastward to the Atlantic Ocean. Also the Gurupá Arch remained high up to the end of Middle Miocene, directing this drainage system westward. With the late subsidence and breaching of the Gurupá Arch and a major fall in sea level, at the beginning of the Late Miocene, the Amazon River quickly opened its pathway to the west, from the Marajó Basin, through deep headward erosion, capturing a vast drainage network from cratonic and Andean areas, which had previously been diverted towards the Caribbean Sea. During this time, the large siliciclastic influx to the Amazon Mouth (Foz do Amazonas) Basin and its fan increased, due to erosion of large tracts of South America, linking the Amazon drainage network to that of the Marajó Basin. This extensive exposure originated the Late Miocene (Tortonian) unconformity, which marks the onset of the transcontinental Amazon River flowing into the Atlantic Ocean.

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“…A coesão é aumentada pela granulação mais fina dos sedimentos, que tornam os bancos mais coesos (Ikeda, 1989;Törnqvist, 1993), conforme verificado nas camadas de lama (silte e argila) que compõem a estratificação heterolítica inclinada das ilhas e barras marginais desse sistema fluvial. Além disso, a maioria das ilhas é vegetada (inclusive por vegetação de médio a grande porte) e apresenta tempo de fixação entre 1.300 e 7.500 anos AP, de acordo com dados de datação por luminescência de cristais e radiocarbono obtidos nos estudos de Sternberg (1960), Absy (1979), Soares (2007), Soares et al (2010) e Rozo et al (2012.…”

Section: Resultados E Discussõesunclassified

“…Estudos geológicos detalhados na região entre Manacapuru-Manaus-Autazes, Amazônia Central (Soares, 2007;Soares et al, 2010;Gonçalves Júnior, 2013), permitiram definir sobre as unidades do Cretáceo-Mioceno (formações Alter do Chão e Novo Remanso) três níveis de terraços fluviais quaternários, constituídos principalmente de areia e lama (argila e silte), com estratificação heterolítica inclinada, que apresentam idade entre 240.000 e 1.300 anos AP. Os terraços estão dispostos em faixas paralelas às margens do sistema fluvial Solimões-Amazonas e são contínuos por dezenas de quilômetros.…”

Section: Contexto Geológicounclassified

Análise multitemporal do sistema fluvial Solimões-Amazonas entre os tributários Purus e Negro, Amazônia Ocidental, Brasil

Passos

Soares

2017

Geol. USP. Sér. Cient.

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Nas últimas décadas, as feições geomorfológicas de trechos do sistema fluvial Solimões-Amazonas têm sido estudadas por meio de imagens de sensores remotos, aliados a dados de análise multitemporal, destacando principalmente as modificações morfológicas das planícies aluviais e canais deste sistema. Os primeiros estudos utilizavam bases cartográficas de menor precisão em comparação às atuais e não consideravam alguns fatores como a cota dos rios, tipos de sensores e imprecisões na aquisição dos dados, o que diminui a acurácia dos dados. Atualmente, dentre os fatores mais enfatizados na análise desse sistema fluvial, destacam-se a taxa de migração dos canais e a definição do estilo fluvial em diferentes trechos, que variam entre os tipos mais conhecidos na literatura. Este trabalho demonstra por meio da análise multitemporal de imagens Landsat-5/TM a fase final de evolução do sistema fluvial Solimões-Amazonas, no trecho entre os tributários Purus e Negro, no decorrer dos anos de 1991 e 2011. As interpretações indicam leve predominância dos processos deposicionais em relação aos erosivos no trecho analisado, com áreas de 8,56 km2 e 6,86 km2, respectivamente, obtendo-se assim uma taxa de migração média de 0,32%/ano. Os processos deposicionais se concentram principalmente na parte convexa dos meandros e nas áreas a jusante das ilhas, incluindo a formação de novas ilhas, e os erosivos na parte côncava dos meandros e a montante das ilhas. Apesar da dinâmica de erosão e deposição observada no trecho estudado deste sistema, foi possível constatar o elevado padrão de estabilidade dos canais, o qual é coerente com dados batimétricos e de taxa de migração de estudos geológicos regionais, que ajudam a caracterizar o atual estilo fluvial anabranching.

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OSL age determinations of Pleistocene fluvial deposits in Central Amazonia

Cited by 50 publications

References 29 publications

A palaeobiogeographic model for biotic diversification within Amazonia over the past three million years

A palaeobiogeographic model for biotic diversification within Amazonia over the past three million years

Eustatic and tectonic change effects in the reversion of the transcontinental Amazon River drainage system

Análise multitemporal do sistema fluvial Solimões-Amazonas entre os tributários Purus e Negro, Amazônia Ocidental, Brasil

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