Chronology of climatic events of the last glacial cycle in the Atlantic tropical west from stable oxygen isotopes

• Grant number: 23/18429-5
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2024
• End date: February 28, 2025
• Field of knowledge: Physical Sciences and Mathematics - Oceanography - Geological Oceanography
• Principal Investigator: Thiago Pereira dos Santos
• Grantee: Lara Valotto Silva
• 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

Over the last few decades, Paleoclimatology has become an extremely necessary scientific field for the correct understanding of current climate changes. Only from an extended temporal reference can it be understood how unprecedented anthropogenic influence has become in the history of planet Earth. However, for climate reconstructions of the past to be used, precise chronological estimates of the geological archive in question are necessary to allow the correct characterization of the forcing/response pair and to provide a correlation between climatic events in distant regions. This Scientific Initiation research project aims to build an age model for the marine sedimentary cores MD23-3652Q and MD23-3653 collected during the MD241 (AMARYLLIS) expedition of the French research vessel R/V Marion Dufresne which took place between June and July 2023. The tool of oxygen isotopic stratigraphy - a classic strategy for determining the ages of marine sedimentary records- will be used to construct this chronology. The sedimentary cores will be sampled every 20 cm, and the removed samples will be processed to extract shells of benthic foraminifera of the genus Cibicides that preserve the isotopic fluctuation of the oceans in their structure. Once the characteristic signal of glacial-interglacial variability is found in the isotopic curve of the cores, these will be compared to reference curves for extracting ages. Computer programs developed for this purpose that perform linear interpolation between two points will facilitate this activity. More modern approaches with algorithms that exploit chronological uncertainty and produce a probabilistic model will also be used. It is expected to produce a robust chronological model for cores MD23-3652Q and MD23-3653 that supports paleoclimatic studies in the western tropical Atlantic.