A multi-proxy approach to paleoenvironmental changes in the southwestern Río de la Plata area (Argentina) during Late Pleistocene

Abstract

In the southwestern margin of the Río de la Plata (Argentina), mining works have uncovered deposits that correspond to the last glacio-eustatic cycle (<120 Ky). Because deposits of this cycle are rare in the area, the studied succession provides an opportunity to study the paleoenvironmental and paleoclimatic evolution of the area during that time. Sedimentary analysis reveal an inner estuarine environment impacted by storm surges, followed by fluvial and eolian depositional environments. The paleontological record of the terrestrial deposits indicates open grasslands and semi-arid climatic conditions that can be biostratigraphically assigned to the Lujanian Stage (late Pleistocene). Nevertheless, the chronology of the succession is hereby modified based on OSL ages and geomorphological evidence suggesting that the lower levels of the studied succession are older than previously thought (i.e. MIS 5e instead of MIS 3). Relative changes of sea level are inferred: the estuarine deposits are related to a period of relative high sea-level (i.e. MIS 5e), and the subsequent fluvial system is associated to a global sea-level fall that reached its lowest point during MIS 2.