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On the age of the marine Eem in northwestern Germany

Winn Kyaw, Glos Rainer, Averdieck Fritz-Rudolf, Erlenkeuser Helmut

Geologos

2000

Vol. 5

41--56

In the last interglacial, the North Sea transgressed over large parts of the Northwest European coastal area from Holland to Denmark, with a passage forming through northern Germany to the paleo-Baltic Sea. Two core holes were drilled in these interglacial deposits in Schleswig-Holstein, North Germany: the first from the regime of the paleo-North Sea, close to the town of Dagebuell, west coast, and the second near the settlement of Krummland, east of Eckemfoerde, from the regime of the paleo-Baltic Sea. Sedimentological, paleontological, and palynological studies, along with high resolution oxygen and carbon isotope stratigraphical work, and absolute dating applying the Thorium/Uranium (Th/U) and Electron Spin Resonance (ESR) methods allowed the reconstruction of the sedimentary facies associations and depositional history of this warm period in North Germany. The absence of large isostatic adjustments rendered it possible to link the local hydrographic and climatic evidence to the global development of this interglacial. Th/U-datings of molluscan shells from the marine transgression at Dagebuell (Senescens Sand unit, 28.1 to 22.1 m b.s.l.) yielded an average of 132±1 ka (n = 4 of 5). The results from the younger units (Turritella Clay; Olander Beds; 12 measurements) and from outcrops of Eemian sediments (14 measurements from 7 localities) suffered from open-system-reactions and did not provide reliable ages. ESR-measurements gave collateral support and assigned a rough age to the upper part of the sequence at Dagebuell. Climatic classification and relative correlation of these units is based on pollen-stratigraphy. In the Krummland core, Eemian beds (26.0 to 19.7 m b.s.l.) spanned the initial terrestrial/lacustrine depositional regime to the brackish/marine environment. Palynological evidence assigned the Eemian sediments to Zone 0 (subarctic) through Zone III (warm Eem) to Stage IVa (cooler Eem), following the pollen zonation by Müller (1974). In Dagebuell, the Senescens Sand unit of Zone IIIc was followed by the Turritella Clay and Lower Olander Beds of Zone IVa/b, and ended with the Upper Olander Beds in Zone V. With reference to the global event stratigraphy of the deep-sea oxygen isotope history and the sea level rise during the penultimate interglacial, the climate optimum of the Eem is found to precede the minimum stage of the global ice sheets and likely relates to 8lsO-Stage 5.5.3. The sedimentological and paleontological characteristics of the Dagebuell depositional sequence as well as the isotope evidence indicated that the sea level continued to rise beyond the Eemian hypsithermal up to a time when climate already grew colder, as is shown by the pollen assemblage, and probably culminated in 5180-Stage 5.5.1.