Uranium-series dating of fen peat horizons from pit Nachtigall in northern Germany

Peat and other terrestrial sediments are important archives of climate forcing. This study discusses the numerical age determination of stratigraphically important Quaternary sequences from clay pit Nachtigall near Holzminden in northern Germany, which have been the subject of debate concerning their chronological classification since they were first described by Grupe in 1929. Uranium-series dating (230Th/U) of different organic horizons as well as sedimentology, including loss-on-ignition (LOI) and palynology was carried out to set up a more reliable chronological framework for the Weser river area. 230Th/U ages were calculated using an isochron approach with the leachate/leachate method for chemical preparation. Open system requirements and specification of sample selection criteria for organic samples are investigated by determination of uranium and thorium composition of the rim layers. Different organic sediments are investigated. The organic deposits from Nachtigall show Middle Pleistocene 230Th/U ages ranging from 227+9−8 ka to 201+15−13 ka and appear to represent a warm temperate phase preceding the Eemian Interglacial (MIS 5e) and the Drenthe Stadial (MIS 6), indicating a correlation with marine isotope substage MIS 7c. These results are in good agreement with the investigation of the pollen spectra indicating a correlation with a warm stage within the Lower Saalian Complex.