Late Pleistocene mollusc assemblages and inferred paleoenvironments from the Andean piedmont of Mendoza, Argentina

This paper is focused on the paleoecological analysis of a mollusc succession cropping out on the right margin of La Estacada stream in the Andean piedmont of Mendoza, Argentina (33°28′ S, 69°03′ W). The stratigraphic section, mainly composed of fine sands, interbedded with levels of silty clays and organic matter, records the interval between 35.2–35.5 14C ka B. P. and 31.5–31.6 14C ka B.P. The mollusc succession is represented by freshwater and land snails: Biomphalaria peregrina (Planorbidae), Lymnaea viator (Lymnaeidae), Succinea meridionalis (Succineidae), Rotadiscus amancaezensis (Charopidae) and Radiodiscus sp. aff. Radiodiscus quillajicola (Charopidae). The dominance of semi-aquatic and hygrophilous land snails, suggests the development of a vegetated shallow water body, probably a damp habitat occasionally submerged, with four main stages of evolution related to fluctuating water levels. The abundance of shells together with the stable isotope composition of carbonate shells of L. viator (δ13C and δ18O) and the presence of Radiodiscus sp. aff. Radiodiscus quillajicola and R. amancaezensis suggest relatively warm and wet conditions. Based on its radiocarbon chronology and the paleoecological reconstruction, the studied section is recording a mild interval corresponding to an interstadial (Marine isotope stage 3) of the last glacial cycle.