Water Masses and Oceanic Circulation of the Brazilian Continental Margin and Adjacent Abyssal Plain

Controlling Parameters of Benthic Deep-Sea Foraminiferal Biogeography at the Brazilian Continental Margin (11-22°S)

“…The BC reaches current velocities between 50-80 cm s -1 in the subtropical SACW at the Campos Basin (de Mello e Sousa et al, 2006). At about 20°S, part of the SACW is deflected northwards (Stramma and England, 1999;da Silveira et al, 2020). Slightly lower salinities distinguish it from the subtropical SACW (Stramma and England, 1999).…”

“…The AAIW, present at water depths between 500 and 1100 m, is distinguishable from SACW by lower salinities of about 34.2 (Mémery et al, 2000;da Silveira et al, 2020;Raddatz et al, 2020). The equatorward flowing NBUC reaches current velocities of up to 80 cm s -1 in the tropical SACW (da Silveira et al, 2020) and up to 30 cm s -1 in the underlying AAIW (Viana, 2001). The layer of the AAIW at the Brazilian continental slope provides an ideal habitat for cold water coral (CWC) mounds which are mainly known from the Campos Basin at depths of 800-900 m (Viana et al, 1998;Bahr et al, 2016;Raddatz et al, 2020).…”

“…The Brazilian margin, with a length of 7400 km, can be divided into different physiographical provinces (Martins and Coutinho, 1981). The north-eastern part stretches from Cabo Sao Roque to Belmonte and includes the Brazil Basin (5-16°S; Figure 1; Martins and Coutinho, 1981;da Silveira et al, 2020). Reduced continental erosion and low marine sedimentation rates result in a very narrow continental shelf (Figures 2A, B) less than 10 km in width (Summerhayes et al, 1976;Knoppers et al, 1999;Bahr et al, 2016).…”

“…Four major water masses strongly affect the Brazilian continental margin to a water depth of 3500 m: the Tropical Water (TW), the South Atlantic Central Water (SACW), the Antarctic Intermediate Water (AAIW) and the North Atlantic Deep Water (NADW; Figure 1; Stramma and England, 1999;da Silveira et al, 2020). The warm and saline TW represents the uppermost layer and extends to a depth of 150 m. Beneath the TW, the nutrient-rich SACW with salinities around 35.8 prevails to a depth of 500 m. Sediments transported from the shelf, facilitated by the complex channel system, are considered a major source of organic matter input to the continental margin and contribute to an enhanced nutrient availability within the SACW (Braga et al, 2008).…”

“…The tropical branch of the SACW, as well as the underlying AAIW, are controlled by the North Brazil Undercurrent (NBUC), which is formed mainly in the northern Drake Passage and the Falkland Current Loop at about 40°S and flows towards the north along the eastern continental margin of South America (Stramma and England, 1999). The AAIW, present at water depths between 500 and 1100 m, is distinguishable from SACW by lower salinities of about 34.2 (Mémery et al, 2000;da Silveira et al, 2020;Raddatz et al, 2020). The equatorward flowing NBUC reaches current velocities of up to 80 cm s -1 in the tropical SACW (da Silveira et al, 2020) and up to 30 cm s -1 in the underlying AAIW (Viana, 2001).…”