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

Abstract

Bioerosion is a valuable tool for inferring palaeoenvironmental and palaeoclimatic changes over timeand across different regions. However, studies of bioerosion traces are scarce in the Southern Hemisphere. Mostichnological studies within Argentina are concentrated in San Jorge Gulf (Patagonia, Argentina) and little is knownabout deposits located north of the Gulf. Here, we focus on bioerosion traces on Quaternary mollusc shells. Sampleswere 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 toconfirm the presence of beach ridge deposits from Marine Isotope Stage (MIS) 5 and MIS 1. Fourteen ichnotaxa arerecorded in the study area. Additionally, distinct variations in the pattern of bioerosion across different ages areobserved, indicating that environmental changes occurred in the northern San Jorge Gulf between the MIS 5interglacial and the Holocene. This reinforces the hypothesis that there is an association between bioerosion,productivity and circulation in the Southern Atlantic Ocean.