Pre-vegetation fluvial floodplains and channel-belts in the Late Neoproterozoic-Cambrian Santa Barbara group (Southern Brazil)

Autor(es)

Marconato, Andre ^[1] ; de Almeida, Renato Paes ^[2] ; Turra, Bruno Boito ^[1] ; dos Santos Fragoso-Cesar, Antonio Romalino ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Geosci, BR-05508080 Sao Paulo, SP - Brazil

^[2] Univ Sao Paulo, Inst Energy & Environm, BR-05508080 Sao Paulo, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: SEDIMENTARY GEOLOGY; v. 300, p. 49-61, MAR 1 2014.
• Citações Web of Science: 23

Resumo

One key element to the understanding of the dynamics of pre-vegetation fluvial systems is the reconstruction of processes operating on their floodplains given that, in modern systems, channel banks and floodplains are the environments most affected by plant colonization. Notwithstanding, few pre-vegetation floodplains have been described, and major questions regarding their most basic characteristics are still unresolved. In order to address these questions, detailed analysis of coeval channel-belt, fluvial floodplain and alluvial-fan deposits from the Santa Barbara Group (Late Neoproterozoic to Early Cambrian, southern Brazil) was performed. While floodplain fades resemble ephemeral stream deposits, being coarser-grained than modem floodplains and marked by the stacking of flood event cycles, channel-belt deposits show composite bars, which do not present conclusive evidence for high water discharge variation. The floodplain deposits show particular features common to other pre-vegetation fluvial systems, such as better preserved small-scale structures, lack of bioturbation, and abundance of cross-laminated sandstones, while other features differ from previous depositional models, namely abundant mudcracks and evidence of soil formation. The lateral variation of depositional systems recorded in the Santa Barbara Group shows contrasting signatures of water discharge variation in sand-dominated coeval environments, and offers an example of the relation between different alluvial environments before the evolution of land plants. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 09/53362-1 - Evolução e controles alogênicos de sistemas aluviais pré-vegetação da Bacia do Camaquã (Neoproterozóico - Cambriano, RS)
• Beneficiário: Renato Paes de Almeida
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 10/51103-6 - Sistemas de planicies de inundacao fluviais pre-vegetacao.
• Beneficiário: André Marconato
• Modalidade de apoio: Bolsas no Brasil - Doutorado
• Processo FAPESP: 13/02114-3 - Paleossolos ediacaranos e cambrianosda Bacia Camaquã, RS
• Beneficiário: André Marconato
• Modalidade de apoio: Bolsas no Exterior - Estágio de Pesquisa - Doutorado