Paleoceanographic evolution of the South Atlantic subtropical gyre over the past 800,000 years based on a multi-proxy approach

Abstract

Terminations (i.e., transitions from glacial to interglacial periods) and interglacial periods are key intervals to understand climate dynamics under increasing and high atmospheric CO2 concentrations, such as Earth's present and future climates. Due to its intrinsic relationship with the Atlantic Meridional overturning circulation and its prominent role in controlling energy distribution and upper ocean buoyancy, the South Atlantic Subtropical Gyre (SASG) is a key, yet poorly understood, feature of the climate system. This project aims to reconstruct the paleoceanographic evolution of the SASG with high-temporal resolution and a multi-proxy approach, generating micropaleontological, inorganic geochemical and isotopic records for the past 800 thousand years (kyr). Therefore, two marine sediment cores collected from the Western South Atlantic will be analyzed for (I) Globorotalia truncatulinoides relative abundances; (II) Mg/Ca ratios, as well as (III) carbon (´13C) and oxygen (´180) stable isotopes on planktonic foraminiferal tests. The records will serve as proxies for upper water column stratification, seawater temperature, salinity and dissolved inorganic carbon ´13C of South Atlantic central water. They are anticipated to unravel the SASG evolution over the past 800 kyr, with special focus on past terminations and interglacial peaks. When accomplished, this project will deliver key paleoceanographic insights for the understanding of critical climate thresholds, as the one the Earth approaches at the moment. (AU)