QUANTITATIVE ASSESSMENT OF POST-WURMIAN I NFILLINGS OF THE LACUSTRINEBASIN OF CERIN (JURA, FRANCE)

In the southern Jura mountains, the lake of Cerin is located in an are a reached by the maximum Rhone Wurmian glacial advance. The retreat of the glacial front occurred after 18.000 years B.P. The glacial tongue of Cerin has overdeeped a lacustrine basin of 35 acres which is nowad ays almost filled up. The morphology of the basin, the nature and geom etry of the lacustrine infillings were determined by geophysical prosp ecting and 52 core drillings. Their chronology is based on pollen stra tigraphy and 14 radiocarbon datings. These chronological references ad ded to a computerized processing of sedimentological data are taken in to account for a reconstruction of the main successive phases of depos it accumulation in the basin and its dynamics of filling up. For each chronological phase we calculated the mean thickness, density and volu mes of the sedimentary facies stored in the natural lacustrine depress ion. So as to get more accurate information about the impact of climat e and vegetation on the sedimentary process, we studied the evolution of the volumes stored in relation, both with the dynamic of filling up and with the environment modifications that occurred during the late glacial and Holocene periods. Results show that variations in sediment accumulation rates reflect a complex interaction between sedimentary process and climatic oscillations.