Stable isotopes as tracers of ocean circulation at intermediate depths in the equatorial Atlantic over the past 14 thousand years

• Grant number: 24/14630-0
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: November 01, 2024
• End date: October 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Cristiano Mazur Chiessi
• Grantee: Gabriel Roque Shimada
• Host Institution: Escola de Artes, Ciências e Humanidades (EACH). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 18/15123-4 - Past perspectives on tipping elements of the climate system: the Amazon Rainforest and the Atlantic Meridional Overturning Circulation (PPTEAM), AP.PFPMCG.JP2

Abstract

The Atlantic Ocean comprises two main meridional circulation cells that play important roles in Earth's climate system. The upper cell transports waters from the Arctic southward, while the lower cell transports waters of Antarctic origin northward. During the glacial-interglacial transitions of the Quaternary, known as "glacial terminations," these two cells altered their geometry, with a deepening of the boundary between them and the transition from chemically stratified water masses to mixed ones. Marine records based on the joint analysis of the stable oxygen (¿18O) and carbon (¿13C) isotope composition in epibenthic foraminifera provide important information about the distribution of water masses in the geological past. Despite the existence of studies on circulation changes based on ¿13C reconstructions in the western South Atlantic, there is a notable scarcity of works characterizing the temporal evolution of water mass mixing by coupling ¿18O and ¿13C records from intermediate depths in the equatorial Atlantic with high temporal resolution. This project will investigate changes in circulation in the western equatorial Atlantic at intermediate depth over the past 14,000 years. To do so, a time series of ¿18O and ¿13C data in epibenthic foraminifera will be generated from a marine sediment core collected in the equatorial Atlantic. The results obtained will be compared with other paleocirculation records from the Atlantic in order to map the boundaries of water masses in the western Atlantic over the past 14,000 years.