Palaeoenvironmental implications of Late Quaternary bioerosion traces in central Patagonia (Southern Atlantic, Argentina)

Bioerosion is a valuable tool for inferring palaeoenvironmental and palaeoclimatic changes over time and across different regions. However, studies of bioerosion traces are scarce in the Southern Hemisphere. Most ichnological studies within Argentina are concentrated in San Jorge Gulf (Patagonia, Argentina) and little is known about deposits located north of the Gulf. Here, we focus on bioerosion traces on Quaternary mollusc shells. Samples were collected from Quaternary marine deposits at the Bahía Vera–Cabo Raso sites in northern San Jorge Gulf. To resolve age discrepancies reported in the literature, we use amino acid racemization and radiocarbon dating to confirm the presence of beach ridge deposits from Marine Isotope Stage (MIS) 5 and MIS 1. Fourteen ichnotaxa are recorded in the study area. Additionally, distinct variations in the pattern of bioerosion across different ages are observed, indicating that environmental changes occurred in the northern San Jorge Gulf between the MIS 5 interglacial and the Holocene. This reinforces the hypothesis that there is an association between bioerosion, productivity and circulation in the Southern Atlantic Ocean.