Lateglacial calendar year chronology based on annually laminated sediments from Lake Meerfelder Maar, Germany

Annually laminated sediments From Lake Meerfelder Maar (MFM) in the Eifel, Germany, provide an independent calendar year timescale for the last glacial/interglacial transition. Changes in varve thickness and varve facies reflect significant environment variations during this period. The general micro facies pattern confirms that diatomaceous organic varves are favoured during warm climatic phases while cold periods generate higher allochthonous sediment fluxes. An exception is the significant increase in diatom blooms at the beginning of the Younger Dryas. Six Lateglacial biozones have been defined by Litt and Stebich (Quaternary International, 1999). The sediment record comprises two tephra layers as chronomarkers. The Laacher See Tephra (12,880 varve years BP) is a continent-wide correlation horizon while the Ulmener Maar Tephra provides regional chronological links. The beginning of the lateglacial warming is dated at 14,450 varve years (vyrs) BP which is regarded as the minimum age. Three abrupt cold spells interrupted the lateglacial interstadial at 13,800 vyrs BP (Oldest Dryas), 13,540 vyrs BP (Older Dryas) and 12,680 vyrs BP (Younger Dryas). The Oldest Dryas (130 years) and the Older Dryas (190 years) were rather short while the Younger Dryas lasted much longer (1090 years). The MFM chronology was compared with ice core timescales from GISP2 and GRIP. There is a good agreement between these timescales, with the GRIP model age (ss09) providing the best match to the MFM chronology. (C) 2000 Elsevier Science Ltd and INQUA. All rights reserved.