Data/hora: 09/06/2024 18:09:14

Biblioteca(s): | Embrapa Pantanal.
Data corrente: | 27/09/2019
Data da última atualização: | 18/11/2019
Autoria: | Lo, E. L.; McGLUE, M. M.; SILVA, A.; BERGIER, I.; YEAGER, K. M.; MACEDO, H. DE.; SWALLOMA, M.; ASSINE, M. L.
Afiliação: | Edward L. Lo, University of Kentucky; Michael M. McGlue, University of Kentucky; AGUINALDO SILVA, UFMS; IVAN BERGIER TAVARES DE LIMA, CPAP; KEVIN M. YEAGER, University of Kentucky; HUDSON DE AZEVEDO MACEDO, UEM; MAREDITH SWALLOMA, University of Kentucky; MARIO L. ASSINE, UNESP.
Título: | Fluvio-lacustrine sedimentary processes and landforms on the distal Paraguay fluvial megafan (Brazil).
Ano de publicação: | 2019
Fonte/Imprenta: | Geomorphology, v. 342, p. 163-175, 2019.
DOI: | 10.1016/j.geomorph.2019.06.001
Idioma: | Inglês
Conteúdo: | Tropical fluvio-lacustrine depositional processes along the toe of the Paraguay fluvialmegafanwere investigated with a focus on Lake Uberaba (LU), the largest lake in the Pantanalwetlands. A limnogeological analysis of LUwas conducted using remote sensing imagery, lake water chemistry, sedimentological and radiochemical data from lake floor samples and short cores. Echo-sounding revealed that LU is deepest (Zmax = ~3.5 m) near its southern shoreline and outlet; the lake is hydrologically open throughout the year and is characterized by a dilute Ca+2-Na+-HCO3 &#8722; chemistry. Key environmental controls on sedimentation in LU include inflowing transverse and axial rivers and water level changes, which influence the composition, mixing, accumulation, and the organization of facies. Structureless brown sandy silts with relatively low organic carbon (TOCmean = ~1.7 wt %) and low to moderate biogenic silica (BiSimean = ~1.9 wt%) comprise most offshore lake floor sediments, whereas northern lake margin sediments consist of peaty silts and sandy silts whose origins are linked to inflowing Paraguay megafan distributary channels. Sediment core stratigraphy revealed that extant lacustrine deposits are underlain by oxidized clayey silts and sands, suggesting recent subaerial exposure of the basin floor. Sedimentary datasets conclusively suggest that LU is a shallow overfilled lake basin that is strongly influenced as a depositional system by its persistently open hydrology, shoreline channel density, and absence of margin coincident topography. This study provides newinsights on lacustrine landformdevelopment in distal megafan settings, which is important for improving our understanding of fluvial landscapes.
Palavras-Chave: | Distributive fluvial system.
Thesagro: | Lago; Sedimento.
Thesaurus Nal: | Fluvial soils; Lakes; Wetlands.
Categoria do assunto: | P Recursos Naturais, Ciências Ambientais e da Terra
Registro original: | Embrapa Pantanal (CPAP)
Exemplares: | CPAP - (60425-1) - UPC - AP - DD - AP -  -  - DIS