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Abstract:
Based on the results of palynological and geochemical analyses, a sediment section near the village of Vevais (north-eastern Brandenburg) is assumed to encompass a succession of Saalian, Eemian and Weichselian sediments and is expected to cover a time span from Marine Isotope Stage (MIS) 6 to MIS 2. It is regarded as a key site for the study of the last interglacial cycle in north-eastern Germany. Palynological analyses had revealed an almost complete record of the Eemian (MIS 5e) preserved within a succession of lake marls exposed in the sediment sequence, but results from numerical dating methods were still missing. Within this study five samples from sand layers within the profile have been analyzed using luminescence dating techniques in order to set up a geochronometrical time frame for the Eemian interglacial. First results from Optically Stimulated Luminescence (OSL) dating of quartz showed severe age underestimation of some samples with regard to their relative stratigraphical position to the Eemian lake marls. Radionuclide analyses revealed disequilibria within the 238U decay chain and inconsistencies concerning the 40K content for most of the samples. In order to overcome these dosimetric problems, additional Infrared Stimulated Luminescence (IRSL) and post-Infrared Yellow OSL (post-IR YOSL) measurements from feldspar were conducted and a ‘subtraction dating’ method was successfully applied. Hence, it was for the first time possible to set up a time frame for the Eemian interglacial inferred from luminescence dating techniques of a terrestrial sedimentary archive in north-eastern Germany. The onset of the Eemian was dated to 126 ± 16 ka. The termination and beginning transition from the Eemian to the Weichselian cold stage was dated to 108.9 ± 7.8 ka. These results are in excellent agreement with the marine isotope record as well as with the results of the analysis of the continuous varve record of Lago Grande di Monticchio, with a period of 17.7 ± 0.2 ka from the onset at 127.2 ± 1.6 ka BP for the Eemian interglacial.
