Palaeoclimatic Development and Stratigraphy of the Walsdorfer Maar (West Eifel Volcanic Field, Germany) During the Latter Half of the Saalian Glacial Period (MIS 7/6)

We investigated the lithology and tephra of the 87-metre-long drill core (WD1) from the Walsdorfer maar (Eifel, Germany) in order to reconstruct the sequence of volcanic activity and its integration into palaeoclimatic developments between Marine Isotope Stage (MIS) 7 and MIS 6. Based on tephra counts, mineralogical and geochemical analyses, we have identified 11 primary tephra layers in the WD1 core that have not previously been described in the Eifel, with an age range of approximately 196–158 ka, alongside 13 reworked tephra layers, particularly in the older part of the core. Leucite was detected in the important marker tephra Hüttenberg Tephra (HBT) at 215 ka and Glees Tephra (GLT) at 151 ka. The basal Walsdorfer Maar Tephra (WDT) dates the outbreak to 217,843 years ago. Our results thus extend the existing ELSA–23–Tephra–Stack for the period 220–130 ka. The results for organic components show that, during the period 215–185 ka (MIS 7c–7a), a predominantly boreal forest consisting mainly of thermophilic deciduous species was established, whilst in the range of 170–152 ka, during the earlier half of MIS 6, hardly any pollen and less organic material have been preserved. The data point to changes in productivity and vegetation dynamics, which are reflected in the composition of the organic matter. The liptinite-rich intervals with higher fluorescence primarily characterise warmer subphases within MIS 7, whereas cool-humid conditions during the glacial MIS 6 favoured the formation of huminite-rich peats. The presence of calcareous layers in the 200–190 ka range indicates formerly wet conditions, suggesting MIS 7a. Palaeotemperature calibrations were analysed by brGDGT and provide the temperature of MAF comparable to Holocene levels. The data from the WD1 core (Eifel) confirm the climatic conditions during MIS 7a as inferred from other European archives, add a new region to the picture, and, because of their high resolution, enable the identification of climatic fluctuations that could not be detected in previous studies. We reconstruct a tephrostratigraphic chronology as well as the palaeoclimatic evolution of the period 220–132 ka in the Walsdorfer maar.