Journal
QUATERNARY SCIENCE REVIEWS
Volume 215, Issue -, Pages 22-34Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.quascirev.2019.04.020
Keywords
U-37(K); TEX86; LDI; Holocene; Pleistocene; Paleoceanography; South Atlantic; Organic geochemistry
Funding
- CAPES (Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior)
- Deutscher Akademischer Austauschdienst (DAAD) [91621623]
- FAPESP (Sao Paulo Science Foundation) [FAPESP: 2010/06147-5, 2015/21834-2]
- CNPq (Brazilian National Council for Scientific and Technological Development) [305763/2011-3]
- Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [15/21834-2] Funding Source: FAPESP
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Millennial-scale oscillations are known to be important in the climatic evolution of the Atlantic basin, but which internal processes originates these oscillations are still uncertain. In this study, we investigated how the Greenland and Antarctic climates affect the SW Atlantic through basin-wide oceanographic features (such as the NADW formation and the Agulhas leakage). We reconstructed sea surface and subsurface temperatures (SST and subT) using three lipid-based biomarker proxies (UK 37, TEX86 and WI indexes) from a sediment core (NAP 63-1) retrieved from the SW Atlantic slope (24.8 S, 44.3 W). This location allowed us to evaluate the temperature oscillations of the Brazil Current without any terrigenous or upwelling-derived biases. Both TEX86-based and LDI-based estimates represent the mean annual SST, while the UK 37-based estimates represent the subT (around 30 m water depth). The periods with the most well-mixed water column were observed during intervals of cooling orbital trends due to the time required to transfer the surface cooling to the subsurface. The temperature reconstructions showed a general colder MIS 3 when compared to the MIS 4. They also showed evidence of a late response to deglaciation, with its onset in the SW Atlantic occurring in the middle of the Last Glacial Maximum. Based on these reconstructions, the NAP 63-1 SST orbital-scale trend seems to be linked to the Antarctic climate, influenced by local insolation changes. These temperature records also presented a clear millennial periodicity around 8 kyr. On this timescale, the millennial oscillations in the SW Atlantic's SST are likely linked to the NADW formation. (C) 2019 Elsevier Ltd. All rights reserved.
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