High resolution sediment and vegetation responses to Younger Dryas climatechange in varved lake sediments from Meerfelder Maar, Germany

This work focuses on a 1900-year section of varved sediments from Lake Meer felder Maar (MFM) extending from the Late Allerod to the Preboreal. Varve c ounting provides the chronological framework and determines the length of Y ounger Dryas to 1025-1090 years. A strong relation between climate change, environment response and depositional processes has been found. In conseque nce, varve microfacies variations are a sensitive proxy for environment cha nges. These are reflected, for example, in erosion processes within the lak e's catchment (minerogenic input) and lake productivity (diatom blooms). Th e observed varve changes have been quantified by multiproxy analyses of phy sical and chemical sediment parameters with a resolution of between 8 and 4 0 years depending on sedimentation rate. In addition, high resolution palyn ological investigations provide the biostratigraphical subdivision based on changes in the vegetation occurring during the same time interval. Varve o bservations reveal that environment changes at the beginning and the end of the Younger Dryas occurred within 20-50 years. Furthermore, sediment and v egetation changes were synchronous. Within the actual precision of the MFM and GRIP chronologies (divergence of only a few decades) terrestrial respon ses in Western Europe occurred quasi-synchronous to temperature changes in Greenland. (C) 1999 Elsevier Science Ltd. All rights reserved.