Control of oceanic circulation on sediment distribution in the southwestern Atlantic margin (23 to 55 degrees S)

Author(s)

de Mahiques, Michel Michaelovitch ^{[1, 2]} ; Violante, Roberto ^[3] ; Franco-Fraguas, Paula ^[4] ; Burone, Leticia ^[4] ; Rocha, Cesar Barbedo ^[5] ; Ortega, Leonardo ^[6] ; dos Santos, Rosangela Felicio ^[1] ; Kim, Bianca Sung Mi ^[1] ; Lopes Figueira, Rubens Cesar ^[1] ; Bicego, Marcia Caruso ^[1]

Affiliation

^[1] Univ Sao Paulo, Oceanog Inst, BR-05508120 Sao Paulo - Brazil

^[2] Univ Sao Paulo, Inst Energy & Environm, BR-05508010 Sao Paulo - Brazil

^[3] Serv Hidrog Naval, C1270ABV, Buenos Aires, DF - Argentina

^[4] Univ Republica, Fac Ciencias, Montevideo 11400 - Uruguay

^[5] Univ Connecticut, Dept Marine Sci, Groton, CT 06340 - USA

^[6] Direcc Nacl Recursos Acuat, Dept Biol Pesquera, Montevideo 11200 - Uruguay

• Document type: Journal article
• Source: Ocean Science; v. 17, n. 5, p. 1213-1229, SEP 15 2021.
• Web of Science Citations: 0

Abstract

In this study, we interpret the role played by ocean circulation in sediment distribution on the southwestern Atlantic margin using radiogenic Nd and Pb isotopes. The latitudinal trends for Pb and Nd isotopes reflect the different current systems acting on the margin. The utilization of the sediment fingerprinting method allowed us to associate the isotopic signatures with the main oceanographic features in the area. We recognized differences between Nd and Pb sources to the Argentinean shelf (carried by the flow of Subantarctic Shelf Water) and slopes (transported by deeper flows). Sediments from Antarctica extend up to the Uruguayan margin, carried by the Upper and Lower Circumpolar Deep Water. Our data confirm that, for shelf and intermediate areas (the upper 1200 m), the transfer of sediments from the Argentinean margin to the north of 35 degrees S is limited by the Subtropical Shelf Front and the basin-wide recirculated Antarctic Intermediate Water. On the southern Brazilian inner and middle shelf, it is possible to recognize the northward influence of the Rio de la Plata sediments carried by the Plata Plume Water. Another flow responsible for sediment transport and deposition on the outer shelf and slope is the southward flow of the Brazil Current. Finally, we propose that the Brazil-Malvinas Confluence and the Santos Bifurcation act as boundaries of geochemical provinces in the area. A conceptual model of sediment sources and transport is provided for the southwestern Atlantic margin. (AU)

• FAPESP's process: 16/22194-0 - Anomalous bottom features on the upper slope off Southern Brazil
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Regular Research Grants
• FAPESP's process: 14/08266-2 - Continental slope morphological features on the SE Brazilian Margin: active tectonics versus modern oceanographic conditions
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Regular Research Grants
• FAPESP's process: 15/17763-2 - Mudbelts from the South and Southeast Brazil: implications about the anthropogenic influence on the marine environment
• Grantee: Márcia Caruso Bícego
• Support Opportunities: Research Projects - Thematic Grants
• FAPESP's process: 19/00256-1 - Geochronology and terrigenous sedimentation of the mud depocenters from the Southern Brazilian continental shelf
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Regular Research Grants