A millennial history of sea level changes in the southwestern Atlantic

Warmer temperatures and smaller-than-present ice sheets generally characterize interglacials. Determining the rates and geographic variability of relative sea-level (RSL) change during these periods provides insights into the future of the coastlines under warmer climatic conditions. Since the early 1940s, RSL studies along the southwestern Atlantic Coasts confirm the presence of several Last Interglacial (LIG, ~128-116 ka) and Holocene (HOL, 11 ka – to present) sea-level indicators. We use WALIS and HOLSEA templates to standardize and evaluate the quality and uncertainties of these published sea-level records. Our preliminary review produced more than 1000 standardized data points (55 LIG and 1177 HOL); more than 300 inconclusive data were rejected after being examined by quality control. Our data indicate that during the LIG, the paleo sea-level values range from ~5.6 to 20 m above sea level (a.s.l.) in the continental sector and from ~2 to 10 m a.s.l. in the Caribbean islands. Regarding the Holocene data, several sites show a mid-Holocene maximum transgression, with RSL rising 2-4 m above its present level, with a subsequent fall to its current position. This trend seems to be predominantly driven by glacial-isostatic adjustment processes. From our review, we identify that the coasts of Brazil, French Guiana, Suriname, Guyana, and Venezuela would benefit from a renewed study of Quaternary sea-level indicators. We also highlight that elevation measurements, sea-level interpretations, as well as chronological control at several locations may be improved by future research. This poster will be presented at GLOMAR/MARUM PhD Days 2023. Ph.D.