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dc.contributor.authorde Almeida, Renato Paes
dc.contributor.authorGaleazzi, Cristiano Padalino
dc.contributor.authorFreitas, Bernardo Tavares
dc.contributor.authorJanikian, Liliane [UNIFESP]
dc.contributor.authorLanniruberto, Marco
dc.contributor.authorMarconato, Andre
dc.identifier.citationEarth And Planetary Science Letters. Amsterdam, v. 454, p. 92-102, 2016.
dc.description.abstractThe interpretation of large river deposits from the rock record is hampered by the scarcity of direct observations of active large river systems. That is particularly true for deep-channel environments, where tens of meters deep flows dominate. These conditions are extremely different from what is found in smaller systems, from which current facies models were derived. MBES and shallow seismic surveys in a selected area of the Upper Amazonas River in Northern Brazil revealed the presence of large compound barchanoid dunes along the channel thalweg. The dunes are characterized by V-shaped, concave-downstream crest lines and convex-up longitudinal profiles, hundreds of meters wide, up to 300 m in wavelength and several meters high. Based on the morphology of compound dunes, expected preserved sedimentary structures are broad, large-scale, low-angle, concave up and downstream cross strata, passing laterally and downstream to inclined cosets. Examples of such structures from large river deposits in the rock record are described in the Silurian Serra Grande Group and the Cretaceous Sao Sebastiao and Marizal formations in Northeastern Brazil, as well as in Triassic Hawkesburry Sandstone in Southeastern Australia and the Plio-Pleistocene Ica Formation in the western Amazon. All these sedimentary structures are found near channel base surfaces and are somewhat coarser than the overlying fluvial deposits, favoring the interpretation of thalweg depositional settings. The recognition of large barchanoid dunes as bedforms restricted to river thalwegs and probably to large river systems brings the possibility of establishing new criteria for the interpretation of fluvial system scale in the rock record. Sedimentary structures compatible with the morphological characteristics of these bedforms seem to be relatively common in large river deposits, given their initial recognition in five different fluvial successions in Brazil and Australia, potentially enabling substantial improvements in facies models for large rivers. (C) 2016 Elsevier B.V. All rights reserved.en
dc.description.sponsorshipFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
dc.description.sponsorshipFAPESP-NSF-NASA Biota/Dimensions of Biodiversity
dc.description.sponsorshipCoordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.publisherElsevier Science Bv
dc.relation.ispartofEarth And Planetary Science Letters
dc.rightsAcesso restrito
dc.subjectlarge riversen
dc.subjectthalweg bedformsen
dc.subjectsedimentary structuresen
dc.subjectMultibeam Echosounderen
dc.titleLarge barchanoid dunes in the Amazon River and the rock record: Implications for interpreting large river systemsen
dc.description.affiliationUniv Sao Paulo, Inst Geociencias, Rua Lago 562,Cidade Univ, BR-05508900 Sao Paulo, SP, Brazil
dc.description.affiliationUniv Sao Paulo, Inst Energia & Ambiente, Ave Prof Luciano Gualberto 1289, BR-05508900 Sao Paulo, SP, Brazil
dc.description.affiliationUniv Estadual Campinas, Fac Tecnol, R Paschoal Marmo 1888, BR-13484332 Limeira, SP, Brazil
dc.description.affiliationUniv Fed Sao Paulo, Campus Baixada Santista,Ave Almirante da Gama 89, BR-11030400 Santos, SP, Brazil
dc.description.affiliationUniv Brasilia, Inst Geociencias, Campus Univ Darcy Ribeiro, BR-71900000 Brasilia, DF, Brazil
dc.description.affiliationUniv Fed Ouro Preto, Escola Minas, BR-35400000 Ouro Preto, MG, Brazil
dc.description.affiliationUnifespUniversidade Federal de São Paulo, Campus Baixada Santista, Av. Almirante Saldanha da Gama, 89, Ponta da Praia, Santos, SP, CEP 11030-400, Brazil
dc.description.sponsorshipIDFAPESP: 2010/51103-6
dc.description.sponsorshipIDFAPESP: 2010/51559-0
dc.description.sponsorshipIDFAPESP: 2013/02114-3
dc.description.sponsorshipIDFAPESP: 2014/09800-2
dc.description.sponsorshipIDFAPESP: 2013/01825-3
dc.description.sponsorshipIDFAPESP: 2014/16739-8
dc.description.sponsorshipIDFAPESP: 12/50260-6
dc.description.sponsorshipIDCAPES: PROEX-558/2011
dc.description.sponsorshipIDCNPq: 302905/2015-4
dc.description.sponsorshipIDCNPq: 301775/ 2012-5
dc.description.sourceWeb of Science

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