Unstable conditions in lake Cari-Laufquen (41º30’08’’S; 69º30’28’’W), Patagonia, during the late Pleistocene (21000-16000 cal yrBP).

PINEDA, D.; CUSMINSKY, G.; SCHWALB, A.,; ARIZTEGUI, D.

San Carlos de Bariloche

Congreso; VI Southern Connections Congress; 2010

CONICET- AGENCIA

Lake Cari-laufquen, located in northern Patagonia, Argentina is one of the few sites providing a long andshort-term climate processes. Studies on shorelines features, demonstrate large lake-level changesduring the late Pleistocene. Here we use ostracodes, from lake Cari-laufquen Grande, in order toreconstruct the palaeoecological, palaeoenvironmental conditions and stability of the environment duringthe late Pleistocene (21.692 ± 288 cal yr BP to 16.960 ± 239 cal yr BP).Four ostracodes species were found from surface sediments sampled along a transect from 1999 lakeshore uphill for 150 to 200m. The species identified are Limnocythere rionegroensis Cusminsky andWhatley, Eucypris virgata Cusminsky and Whatley, Eucypris fontana (Graf) and Limnocythere patagonica Cusminsky and Whatley. Two associations were distinguished the first composed of L. rionegroensis and E. virgata, between sample M1.20 to M1.28, characteristic of freshwater environment, and the second,between sample M1.29 to M1.40, by L. rionegroensis and E. fontana characteristic of saline environment.These variations reflect a change from a freshwater to saline lake system during the late Pleistocenedocumented a high lake level stage and a lower thereafter. This is consistent with other studies, whereestablished that the conditions during Pleistocene were moister and cold. Later on, the environmentalconditions changed to arid leading to a shrinking of the lake and turning the conditions saline.