Multi-proxy reconstruction of sea surface and subsurface temperatures in the western South Atlantic over the last similar to 75 kyr

Author(s)

Dauner, Ana Lucia L. ^{[1, 2]} ; Mollenhauer, Gesine ^{[3, 4]} ; Bicego, Marcia Caruso ^[5] ; de Souza, Mihael Machado ^[6] ; Nagai, Renata Hanae ^[1] ; Lopes Figueira, Rubens Cesar ^[5] ; de Mahiques, Michel Michaelovitch ^{[5, 7]} ; de Mello e Sousa, Silvia Helena ^[5] ; Martins, Cesar C. ^[1]

Affiliation

^[1] Univ Fed Parana, Ctr Marine Studies, BR-83255976 Pontal Do Parana, PR - Brazil

^[2] Univ Fed Parana, Grad Program Coastal & Ocean Syst PGSISCO, BR-83255976 Pontal Do Parana, PR - Brazil

^[3] Univ Bremen, MARUM Ctr Marine Environm Sci, D-28334 Bremen - Germany

^[4] Helmholtz Ctr Polar & Marine Res, Alfred Wegener Inst, D-27515 Bremerhaven - Germany

^[5] Univ Sao Paulo, Oceanog Inst, BR-05508120 Sao Paulo - Brazil

^[6] Hamburg Univ, Inst Oceanog, D-20146 Hamburg - Germany

^[7] Univ Sao Paulo, Inst Energy & Environm, BR-05508120 Sao Paulo - Brazil

• Document type: Journal article
• Source: QUATERNARY SCIENCE REVIEWS; v. 215, p. 22-34, JUL 1 2019.
• Web of Science Citations: 0

Abstract

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. (AU)

• FAPESP's process: 15/21834-2 - Characterization of the sedimentary organic matter off the São Sebastião Island, on Southeastern Brazilian continental shelf using organic biomarkers
• Grantee: Márcia Caruso Bícego
• Support Opportunities: Research Program on Global Climate Change - Regular Grants
• FAPESP's process: 10/06147-5 - Increase of the research capabilities in oceanography and related sciences in São Paulo State, Brazil
• Grantee: Michel Michaelovitch de Mahiques
• Support Opportunities: Research Program on Global Climate Change - Regular Grants