Freshwater invertebrate assemblages and environmental changes in the Late Pleistocene-Holocene of Salto de Piedra site (central Pampean Region, Buenos Aires, Argentina)

Salto de Piedra is a paleontological site located in the Buenos Aires Province (Argentina) close to Olavarría City at the upper basin of Tapalqué Creek. This site provides new insights about the late Quaternary climatic evolution of the area. The taxonomic and taphonomic analyses of freshwater gastropods from this period allow us to evaluate the magnitude of environmental changes in the area. Paleoclimatic inferences at the top of the sequence (Late Pleistocene) indicate a trend from arid conditions at facies 8 to humid ones towards facies 11 (Early Holocene). This transition from arid to humid conditions is also reinforced by post-depositional taphonomic processes. These bioindicators are analyzed with data on the geochemistry of the deposits containing them. Results indicate the alternation of palustrine and lacustrine conditions. These variations of local conditions are correlated with regional records of nearby archaeological sites that inferred arid to humid environmental transitions.