CLIMATICALLY INDUCED LAKE LEVEL CHANGES AT LAKE VAN, TURKEY, DURING THE PLEISTOCENE HOLOCENE TRANSITION/

Sediment core K10 from Lake Van (eastern Turkey) provides a continuous varve record back to 14,570 calendar years B.P. (before present, 1950 ), the longest unbroken and non-floating lake varve sequence yet descr ibed. The underlying sediment is unvarved and hard. Changes in the ara gonite/calcite ratio, the presence of protodolomite and magnesite in c ertain profile sections, the annual record of the sedimentation rate, the water content of the sediment, the concentrations of organic carbo n and opal, and the texture of the sediments from this core provide a record of the lake level history. The new chronology enabled us to red ate the old pollen profile [van Zeist and Woldring, 1978a, b] and to e stablish an accurate timescale for the reconstructed lake level change . Carbon 14 dates show that the highest lake terrace corresponds to hi gh lake level at around 19,000 years B.P. during the Last Glacial, >70 m above its present level. Before 15,000 years B.P. the lake must hav e been completely dry, marking a reduction of lake level by 500 m in m aximum 4000 years. Beginning at 14,600 years B.P. and ending at 12,040 years B.P., the lake level recovered by 250 m to fall again during th e next 1400 years. By 10,600 years B.P. the lake began to rise and rea ched, following another regression between 9000 and 8100 years B.P., t he Holocene highstand by about 7500 years B.P., dropping to today's le vel at about 3000 years B.P.