Annually laminated lake sediments in Estonia

ANNUALLY LAMINATED LAKE SEDIMENTS IN ESTONIA.(Poster 17) Laminated sediments give an opportunity to establish sediment chronologies of one yearresolution, estimate the reliability of radiocarbon dates, set up an absolute chronology for vegetationhistory, climate changes, human impact, shore displacement curves and climatic reconstructions, to studylake eutrophication history and pollution. There are about 150 out of 1500 lakes in Estonia that can containvarved sediments according to their morphometrical parameters. So far four lakes have been found inEstonia, which contain a laminated sediment record from the top to the bottom. The predicted temporalrange of annually laminated lake sediments in Estonia is 14,000 years. The 14C dates obtained from LakesRõuge Tõugjärv and Kasaritsa Verijärv (Southern Estonia) show a 7 and 9-m column of annual laminationssince about 10 000 years BP. 1. The main goal of the annually laminated lake project in Estonia is to find,describe, date and clarify the geoevents of different temporal and spatial range. 2. To reconstruct theenvironmental and climate conditions, the trends of vegetation changes which correspond to the rapidevents. Varve thickness variations of the last centuries will be compared to meteorological and tree-ringdata of the same period to obtain a varve-climate link, which then could be extrapolated to the past. Post-glacial climatic variability and environmental changes are established using diatom-inferred reconstruction.Abrupt transitions between time periods of stable climatic conditions (e.g. the Younger Dryas-Holocenetransition, the early Preboreal Oscillation, cooling events at ca. 8200 years BP and at ca. 2800-2700 yearsBP, the Little Ice Age) are studied at a high-temporal (an annual and possibly seasonal) resolution. 3.Similar links are searched between palaeoecological data (pollen) and historical maps (going back to AD1680) to find modern and historical analogues to generate predictive models of the quantitative relationshipbetween pollen and vegetation (in cooperation with POLLANDCAL). 4. To correlate the established eventswith those in the neighbouring areas

PAGES Meeting on "High Latitude Paleo-environments". Moskva, 16-17. mai 2002