A NEW OCCURRENCE OF LAACHER SEE TEPHRA IN THE CENTRAL JURA (FRANCE) -THE MIRE OF LE LAUTREY

The nature and the geometry of the infillings accumulated in the basin of Lake Lautrey, Central Jura (France), have been identified from 35 cores. A millimetric ash layer was visible to the naked eye in 21 of t he cores located in the deeper parts of the basin. Palynological analy ses indicate that the tephra deposition occurred before the Allerod te rmination. Mineralogical analyses indicate that the tephra layer displ ays the same composition as the Laacher See Tephra, dated at ca. 11 00 0 years B.P. From the pollen diagram, the Laacher See euption appears to have had a limited impact on vegetation of up to 10 years. Based on a sedimentation accumulation rate calculated from 12 cores, the time- span between the LST deposition and the Younger Dryas onset is evaluat ed at ca. 250 years, i.e. a similar value to those obtained from Swiss and German sites.