The Southern Brazilian shelf: general characteristics, quaternary evolution and sediment distribution

  • Michel Michaelovitch de Mahiques Universidade de São Paulo; Instituto Oceanográfico
  • Silvia Helena de Mello e Sousa Universidade de São Paulo; Instituto Oceanográfico
  • Valdenir Veronese Furtado Universidade de São Paulo; Instituto Oceanográfico
  • Moysés Gonsalez Tessler Universidade de São Paulo; Instituto Oceanográfico
  • Felipe Antonio de Lima Toledo Universidade de São Paulo; Instituto Oceanográfico
  • Leticia Burone Universidade de São Paulo; Instituto Oceanográfico
  • Rubens Cesar Lopes Figueira Universidade de São Paulo; Instituto Oceanográfico
  • Daniel Andreas Klein Conservação Internacional
  • Cristina Celia Martins Companhia Ambiental do Estado de São Paulo
  • Daniel Pavani Vicente Alves Universidade de São Paulo; Instituto Oceanográfico
Keywords: Continental shelf, Sedimentation, Sea level changes, Last glacial cycle

Abstract

Extending from latitude 34ºS to 22ºS the Southern Brazilian shelf constitutes the only part of the Brazilian shelf with a subtropical to temperate environment. The studies on the different geological aspects of the area began in the 1960's and have recently been reassessed after studies related to the determination of the Economic Exclusive Zone. In terms of morphology, the Southern Brazilian shelf may be divided into three sectors, the São Paulo Bight, the Florianópolis-Mostardas Sector and the Rio Grande Cone, characterized by conspicuous differences in terms of geological determining factors, bathymetry, declivities and the presence of canyons and channels. Despite the existence of hundreds of radiocarbon datings the sea level changes curve of southern Brazil during the Last Glacial Cycle is still a matter of debate. A recent controversy on the Middle and late Holocene sea level changes curve raised the question of the amplitude of the oscillations which occurred in the period. Also, a few but relatively consistent radiocarbon datings suggest the occurrence of a high sea level during Isotope Stage 3. In terms of sedimentary cover the Southern Brazilian shelf exhibits a very strong hydrodynamic control, both latitudinal and bathymetrical. The sector southward from 25ºS is characterized by the influence of the plume of water carrying sediments originating from the Río de La Plata. Actually its presence is conspicuous up to 28ºS, with the area between this latitude and 25ºS constituting a transitional zone. In terms of bathymetry the outer shelf is marked by the "floor-polisher" effect of the Brazil Current, which is responsible for the maintenance of a relict facies in areas deeper than 100 meters.

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Published
2010-01-01
How to Cite
Mahiques, M., Sousa, S., Furtado, V., Tessler, M., Toledo, F., Burone, L., Figueira, R., Klein, D., Martins, C., & Alves, D. (2010). The Southern Brazilian shelf: general characteristics, quaternary evolution and sediment distribution . Brazilian Journal of Oceanography, 58(spe2), 25-34. https://doi.org/10.1590/S1679-87592010000600004
Section
naodefinida