Post-Wisconsinian paleoenvironments at Salinas del Bebedero basin, San Luis, Argentina

We present a climatic reconstruction of Holocene lacustrine episodes in the Salinas del Bebedero basin (Argentina), based on geological and diatom inf ormation. Morphological, sedimentological and diatom evidence between 11 600 +/- 140 yr BP and 325 +/- 95 yr BP, allowed us to interpret the paleoenvironments o f the basin. Episodes of high energy (sandy levels) are linked to large inf low of meltwater through the Desaguadero River, related to development of g laciers on the Andes. This inflow is characterized by peaks of relative abu ndance of the brackish water diatom Cyclotella choctawatcheeana Prasad. The values of C. choctawatcheeana decrease in deposits of low energy (clay lev els), where it co-dominates with oligohalobous Fragilaria and Epithemia spp . To the last two peaks of large inflow of meltwater, radiocarbon dates corre cted to sidereal ages, are AD 1280/1420 and AD 1443/1656. These ages agree with two cold episodes clearly recorded in dendrological studies from the P atagonian Andes and were correlated to the Little Ice Age. Thus, older Holo cene episodes of large inflow of water to the basin were correlated with th e Neoglacial Advances defined by Mercer (1976) for the Andes.