The effect of sediment loading from the Río de la Plata: driving regional sea-level variability

Sea-level reconstructions are essential for evaluating models of ice-sheet stability and climate change, but their interpretation is often confounded by sea-level signals produced by multiple processes, including the Earth’s deformation in response to sediment loading. Here we show that accounting for sediment isostasy resolves long-standing inconsistencies among Marine Isotopic Stage (MIS) 5a and 5e sea-level records from the Río de la Plata estuary, reducing mismatches by up to an order of magnitude. This result demonstrates that regional sedimentary histories can bias relative sea-level estimates by several meters compared with conventional approaches based only on glacial isostatic adjustment (GIA). We also show that sediment loading has affected relative sea level across the Holocene and may continue to influence present-day tide-gauge observations in the region. Together, these findings emphasize the need for regionally detailed sedimentation histories rather than reliance on global compilations alone, and they motivate expanded shelf coring and seismic surveying.