Late Pleistocene and Holocene palaeoenvironments in Golfo San Jorge, Patagonia: molluscan evidence

Abstract

Palaeoenvironments suggested by molluscan assemblages preserved in Late Pleistocene and Holocene raised marine terraces along the Golfo San Jorge, central Patagonia coastline, Argentina, are reviewed in this work. A better precision of the stratigraphical and geographical ranges of the molluscs through their systematic review shows that all taxa have living representatives, mostly within the Argentine and/or Magellanean Zoogeographical Provinces. In general, no significant taxonomic appearances or disappearances are evident along this coastal area since the last Pleistocene highstand, reinforcing that the modern palaeoceanographical pattern, dominated by the cool Malvinas (Falkland) Current, has not been substantially modified and that the Magellanean Malacological Province has lasted at least since the Pleistocene (although with varying boundaries). The so-called marine terrace V, recently assigned to the Last Interglacial highstand (Oxygen Isotope Substage 5e?), showed in this area a molluscan assemblage characterised by very low diversity, dominantly large shells of Mulinia edulis and by cold-water taxa, in disagreement with higher sea surface temperatures within Oxygen Isotope Substage 5e (Last Interglacial Maximum) and suggesting softer substrates than in the modern adjacent littoral zone.