Dry late-glacial and early Holocene climate in arid central Asia indicated by lithological and palynological evidence from Bosten Lake, China

Stratigraphical and chronological investigations of four sediment cores from Bosten Lake, the largest inland freshwater lake in China, provide a reliable regional environmental evolution record since the late-glacial. The stratigraphy of the four cores has been well correlated according to their lithology and chronology (OSL and C-14 dates). Pollen and grain size data from Bosten Lake show evidence for a dry regional climate during late-glacial and early Holocene (16-8 calka BP) indicated by a thick layer of aeolian sand deposit (> 100 cm). Although the climate became humid after 8 cat ka BP, analysis of pollen assemblages (pollen A/C ratio and Ephedra percentage) also indicates that the climate was relatively dry in the Bosten Lake area between 8 and 6 cat ka BP, while afterwards more humid conditions (ca 6-1.5 cat ka BP) are assumed. Comparison with other lake records from arid central Asia influenced by the westerly winds generally supports the assumption of late-glacial to early Holocene dry climates in westerly dominated regions. Hence, they contrast the Holocene climate development in monsoon Asia. Relatively wet conditions during the late Holocene (6-1.5 cat ka BP) might be induced by stronger westerly circulation. (C) 2007 Elsevier Ltd and INQUA. All rights reserved.