Paleoceanographic changes on the Brazilian S/SE continental margin during the Last Glacial Cycle: A multiproxy approach

• Grant number: 24/02937-4
• Support Opportunities: Scholarships in Brazil - Doctorate
• Start date: August 01, 2024
• End date: October 31, 2026
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Renata Hanae Nagai
• Grantee: Aislyn Alvarenga
• Host Institution: Instituto Oceanográfico (IO). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 20/14356-5 - The Santos Bifurcation: present and past, AP.PFPMCG.TEM
• Associated scholarship(s): 24/19204-0 - Temperature variations of sea surface and intermediate waters of the Brazilian S/SE margin since the Last Glacial Maximum: Evidence based on foraminiferal trace elements., BE.EP.DR

Abstract

The Last Glacial Cycle (last 125 kyr) is marked by several glacial and interglacial climate fluctuations, in addition to a succession of abrupt climatic events that marked the geological record. The Atlantic Meridional Overturning Circulation (AMOC) performed a central role in controlling the global climate in this period, influencing patterns of temperature, stratification, salinity, and ocean productivity on scales of decades to millennia. Variations in the intensity of the AMOC influenced the hydrodynamics of the Brazilian margin, presenting an antiphasic relationship with the Brazil Current, resulting in positive anomalies in sea surface temperature (SST) and oceanic productivity at times when the AMOC was weakened. However, there is still no consensus in the literature on the response of intermediate waters. In this context, the present work aims to evaluate how changes in the intensity of the AMOC impacted the hydrographic conditions of the surface and intermediate waters of the Southwest Atlantic throughout the Last Glacial Cycle, as well as the importance of regional factors for the paleoproductivity of the region. To achieve this, geochemical and microfaunistic proxies based on planktonic and benthic foraminifera will be applied to two marine sedimentary cores collected on the upper slope of the Brazilian S/SE continental margin. The results generated should provide new insights into the response of the environmental and hydrodynamic conditions of the surface and intermediate waters of the Southwest Atlantic and the AMOC. These results are fundamental to interpreting the complexity in temperature patterns and regional and inter-hemispheric nutrient input, reducing gaps in scientific knowledge about the response of intermediate waters to global climate change and its interaction with the AMOC.