Last Interglacial sea-level proxies along the Brazilian western Atlantic coasts

Geological sea-level proxies, such as fossil intertidal or foreshore deposits, store fundamental information that allow reconstructing past changes in sea level, which may be used to evaluate the volume of ice sheets during past warm periods. Studies on Last Interglacial (LIG; Marine Isotope Stage 5e, ~ 125 ka) sea-level proxies are particularly important, as this highstand is a process analogue for the current interglacial, including warming caused by human greenhouse gas emissions. In fact, the LIG was characterized by slightly higher temperatures than the pre-industrial, that caused higher global sea level and, in turn, smaller ice-sheets.

This work was done in the framework of the WARMCOAST Project funded by the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovative Program (Grant Agreement No. 802414). This part of the project aims at surveying new geological sea-level proxies along the western Atlantic Brazilian coast, from Rio Grande do Sul to São Paulo and in southern Bahia State. Classical geological and geomorphological surveys were carried out in the field. We collected several samples for OSL dating and micropaleontological analysis. Samples consist mostly of shallow-water marine sands of supposed LIG age. The elevation of each proxy has been measured by a GNSS RTK station with centimetric precision and referred to a local geoid model (MAPGEO2015).

In this work, we report the results of the field campaign along the Brazil coast and, the new data are interpreted in terms of Glacio-Isostatic Adjustment processes affecting the coasts since the Last Interglacial.