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(Reference retrieved automatically from Web of Science through information on FAPESP grant and its corresponding number as mentioned in the publication by the authors.)

Late Quaternary Cuiaba megafan, Brazilian Pantanal: Channel patterns and paleoenvironmental changes

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Author(s):
Pupim, Fabiano do Nascimento ; Assine, Mario Luis ; Sawakuchi, Andre Oliveira
Total Authors: 3
Document type: Journal article
Source: QUATERNARY INTERNATIONAL; v. 438, n. A, p. 108-125, MAY 5 2017.
Web of Science Citations: 7
Abstract

The Brazilian Pantanal wetlands comprise some of the largest Quaternary megafans in South America. The origin of these megafans has been linked to climate changes during the Late Quaternary. This study focuses on the Cuiaba megafan, the second largest megafan of the Pantanal, which has not been studied from the perspective of its basic geomorphology, river channel patterns and sediment deposition ages. Analysis of the channel and floodplain morphology as well as optically stimulated luminescence dating enable us to establish the succession of events that built up the Cuiaba megafan since the last glacial period. Abandoned lobes indicate that a phase of fan aggradation occurred between 48 and 19 ka, with a network of distributary paleochannels suggesting that there was relatively low precipitation and reduced vegetation cover. Subsequently, abrupt changes in discharge and sediment supply triggered the channel incision of the upper fan valley, indicating a degradational phase after the Last Glacial Maximum (<19 lea). A new phase of fan aggradation began at the Early Holocene, when meandering and anabranching channels were constrained into the incised valley on the upper fan. In the distal part of the fan, the development of modern depositional lobes has been driven by numerous single-sinuous channels that shift laterally due to successive avulsions. Regional tectonic features suggest that modern Cuiaba lobes are in a subsiding area that provides accommodation space for sediment accumulation and prolonged flooding events. Changes in the channel patterns observed in the Cuiaba megafan are related to changes in the South American monsoon strength, which driven precipitation variation during the Late Quaternary. Periods of monsoon intensification and relatively high precipitation lead to channel incision, while periods of fan aggradation correlate to times of fewer oscillations. Our findings highlighted the diversity of fluvial styles in the Pantanal and its importance as a climate changes archives in the South American lowlands. (C) 2017 Elsevier Ltd and INQUA. All rights reserved. (AU)

FAPESP's process: 09/53988-8 - Acquisition of a luminescence dating system and a precision microsampler for the study of environmental changes in the Quaternary period
Grantee:Paulo César Fonseca Giannini
Support type: Multi-user Equipment Program
FAPESP's process: 14/23334-4 - Coupling Optically Stimulated Luminescence (OSL) and Terrestrial Cosmogenic Nuclides (TCN) analysis to reconstruct changes in the Amazonian fluvial system in the Late Cenozoic (<5 Ma)
Grantee:Fabiano Do Nascimento Pupim
Support type: Scholarships in Brazil - Post-Doctorate
FAPESP's process: 14/06889-2 - Paleohydrological changes, chronology of events and sediment dynamics in the quaternary of the Pantanal Wetland
Grantee:Mario Luis Assine
Support type: Research Program on Global Climate Change - Regular Grants