Chapter 5 The southern Brazilian shelf

Abstract

The southern Brazilian shelf (extending from 348S to 228S) is discussed with special emphasis on its Holocene sedimentary evolution. The onset of the Rio de la Plata plume influence on the inner shelf during the Late Holocene and the reworking of seafloor sediments by the Brazil Current in the outer shelf and upper slope are key elements. High-resolution sedimentary records have revealed palaeoceanographic changes in the Brazilian shelf, highlighting the importance of this sector of the Brazilian shelf to the comprehension of the palaeoclimate of South America, especially regarding oscillations of wind regime and humidity. These records also reveal that the recent sedimentary and oceanographic contrasts north and south of São Sebastião Island (248S) have been present in the Brazilian shelf at least since the Early Holocene.

Offshore and coastal common bottlenose dolphins of the western South Atlantic face‐to‐face: What the skull and the spine can tell us

“…); the area was later inundated by the sea, reaching a Mid‐Holocene sea‐level highstand and decreasing towards present (see Nagai et al . ), which led to the formation of several sheltered areas along the coast (see Ponce et al . ).…”

Two new conceptual models for the formation and degradation of baymouth spits by longshore drift and fluvial discharge (Iguape, SE Brazil)

“…In winter and early spring (May-September), rainfall is mainly due to the extra tropical circulation regime due to migratory cyclones along the subtropical Atlantic coast. In the warm season (September-April), rainfall is related to the activity of the South American Summer Monsoon (SASM), which is responsible for more than 80% of the annual mean precipitation in its activity centre (23°S) and for 50% of the total summer precipitation on the coast south of 25°S (Vera et al, 2002;Nagai et al, 2014). As a result of the typical variations in the rainfall pattern, the outflow in the lower course of the Ribeira de Iguape River ranges from 300 to more than 1200 m 3 /s .…”

Organic biomarker records spanning the last 34,800 years from the southeastern Brazilian upper slope: links between sea surface temperature, displacement of the Brazil Current, and marine productivity

“…Therefore, the outer-shelf and upper-slope topography would have been the main factors that controlled the LGM water mass dynamics (Nagai et al 2014). Nagai et al (2014) drew attention to a considerable change in sedimentation during the Holocene.…”

“…Therefore, the outer-shelf and upper-slope topography would have been the main factors that controlled the LGM water mass dynamics (Nagai et al 2014). Nagai et al (2014) drew attention to a considerable change in sedimentation during the Holocene. High-resolution Holocene sediment profiles collected from the Brazilian shelf revealed notable variability in grain sizes, sediment composition, and benthic foraminiferal assemblages, indicating that sediment input, productivity, and current strength were all affected by sea-level oscillations, as well as changes in wind regime and discharge from the Rio de la Plata over the last 9,000 years (Mahiques et al 2009;Gyllencreutz et al 2010).…”

“…High-resolution Holocene sediment profiles collected from the Brazilian shelf revealed notable variability in grain sizes, sediment composition, and benthic foraminiferal assemblages, indicating that sediment input, productivity, and current strength were all affected by sea-level oscillations, as well as changes in wind regime and discharge from the Rio de la Plata over the last 9,000 years (Mahiques et al 2009;Gyllencreutz et al 2010). Along the Brazilian continental margin, hydrodynamic changes driven by sea-level fluctuations promoted the offshore displacement of the BC, and resulted in variations in the influence of this current on the shelf (Mahiques et al 2007;Nagai et al 2014). …”