Uranium-series and 14C dating of salar sediments in the High Atacama

The Atacama Desert is a key site for the study of Quaternary climatic changes in the Southern Hemisphere. Recently the regional chronology of lake-level fluctuations from the late-glacial/early Holocene humid phase along a high altitude transect (3500 to 4500 m) between 18°S and 28°S in the Southwestern Altiplano of Northern Chile has been revised substantially [1]. The results of 14C dating of organic and inorganic carbon from lacustrine sediments of lake cores in the Atacama Altiplano yielded apparent ages which are too large due to the reservoir effect. The correction is in the order of 100 to 1000 years for organic carbon and in the order of 1000 to 10,000 years for inorganic carbon. The reservoir correction is specific for each lake and varies through history of the lake with changing lacustrine conditions [2]. 210Pb ages of modern sedi-ments confirmed the calibration of the corrected 14C time scale. The reservoir effect is reflected by 14C dates from a large number of organic and inorganic sam-ples from paleolakes in the Atacama Altiplano between 18°S and 25°S. According to the new late-glacial/early Holocene chronology the paleolake transgression began after 13,000- 12,000 14C BP, and culminated between 10,800 and 8800 14C BP interrupted by a dry event of unknown duration. The paleolakes fell between 8800 and 8100 14C BP, and had disappeared by aroun