Evolution of climate in central Europe during late glacial and holocene: Evidence from isotope and palynological records in lacustrine sediments of Polish lakes

Isotope and palynological investigations as presented in the paper were performed on cores from the bottom sediments of three lakes: Mikolajki, Strazym, and Gosciaz situated in central and northern Poland. Stable isotope ratios 18O/16O and 13C/12C were measured in authigenic carbonates deposited in the three studied lakes which started their sedimentation in the late Allerod (Lake Gosciaz), Younger Dryas (Lake Strazym), and Preboreal (Lake Mikolajki). The δ18O record shows a rapid change of approximately 2 per mille at the transition from Allerod to Younger Dryas (AL/YD) and from Younger Dryas to Preboreal (YD/PB). The Holocene climatic optimum at about 5000 years BP is reflected by a broad maximum of the δ18O curve. An annually laminated bottom sediment from Lake Gosciaz enabled the construction of a high resolution record of climate change in central Europe during the late Glacial/Holocene transition on the basis of the five well correlated cores. This record, based on the isotope and palynological data, indicates that onset and termination of the Younger Dryas were rapid and completed within about 150 and 80 years, respectively. A direct counting of varves shows that Younger Dryas lasted approximately 1140 years, a considerably longer period than that derived from other European lakes and comparable with the recent estimates based on the Greenland ice core data. The δ13C record in Lake Gosciaz reveals a negative correlation with the δ18O curve, especially pronounced during the transition periods, suggesting disturbances of the biological activity in the catchment area and in the lake itself during the time of rapid climatic changes. Comprehensive palynological data available for the three studied lakes are in very good agreement with the isotope records and confirm changes of the plant communities typical of the investigated area and climatic fluctuations during Late Glacial and Early Holocene. (author). 22 refs, 3 figs