Publication Date:
2023-12-18
Description:
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 LDI indexes) from a sediment core (NAP 63-1) retrieved from the SW Atlantic slope (24.8°S, 44.3°W). This location permitted 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 the 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.
Keywords:
AC07/02; AGE; Alkenone, unsaturation index UK'37; Alpha-Crucis; Calculated after Rampen et al. (2012); Calculated from TEX86H (Kim et al., 2012); Calculated from UK'37 (Müller et al, 1998); Depth, bottom/max; DEPTH, sediment/rock; Depth, top/min; Gas chromatography - Flame Ionization Detection (GC-FID); Gas chromatography - Mass spectrometry (GC-MS); High Performance Liquid Chromatography (HPLC-APCI-MS); Holocene; LDI; Long chain diol index; NAP_63-1; Organic Geochemistry; paleoceanography; PC; Piston corer; Pleistocene; Sea surface temperature, annual mean; South Atlantic; South Brazil Bight, Santos Basin; Tetraether index of 86 carbon atoms; Tetraether index of 86 carbon atoms, high-temperature region; TEX86; UK'37
Type:
Dataset
Format:
text/tab-separated-values, 974 data points
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