Ice-sheet dynamics and climate fluctuations during the Weichselian glaciation along the southwestern Baltic Sea Coast
Final Report Abstract
The Scandinavian Ice Sheet (SIS) was one of the main ice masses in the northern hemisphere during the Pleistocene and covered large regions of the North European Plain. This DFG project that investigated the glacial and interglacial deposits has helped to understand the complicated response of the SIS to climate fluctuations during the last interglacial-glacial cycle. This project aimed to develop a palaeogeographic and chronostratigraphic model of the southwestern Baltic Sea area, to improve our understanding of the depositional history of the Late Pleistocene, on both a local and a transregional scale. New sedimentological, palaeontological and numerical age data were presented from seven reference sites located at the coast of NE Germany. These new data resulted in a more reliable reconstruction of the depositional environments and a correlation between Weichselian successions from NE Germany and other circum-Baltic regions. The crucial profiles were investigated using a multiproxy approach (sedimentology, micromorphology, physical age dating, and palaeontology). Together, these successions represent the Late Saalian to Late Weichselian period and give rise to the following picture. The oldest dated Pleistocene deposits in the SW Baltic Sea area document a period of deglaciation between ~139-134 ka (Termination II; MIS 6), which is recorded by a glaciofluvial to glaciolacustrine sequence at Klein Klütz Höved, deposited under arctic to subarctic conditions. During this time, the landscape was vegetated by typical Late Saalian flora communities. The Eemian interglacial is represented by lacustrine to brackish deposits covering the reference pollen zones 1 to 3. The presence of brackish ostracods indicates the influence of a marine transgression between 300 and 750 years after the beginning of the Eemian period. Deposits of the early Weichselian were not identified. During the middle Weichselian (between 47-42 ka), ice-free conditions dominated the research area of Jasmund. Deposition occurred in a steppe-like environment with moderate summers and cool winters. Meandering and braided river systems inhabited by various freshwater species, such as Anodonta cygnea, Pisidium amnicum and Perca fluviatilis, shaped the landscape. A subsequent cooling phase resulted in the establishment of a periglacial landscape and the formation of ice-wedges. This phase correlates with the Klintholm advance documented at 34±4 ka in Denmark. The data indicate the formation of a lacustrine basin during the transition of MIS 3 to MIS 2 under sub-arctic climate conditions. A link to the Kattegat ice advance (29 – 26 ka) is likely. At 23±2 ka, the study area was characterised by proglacial and ice-contact lakes related to the Last Glacial Maximum ice advance of the SIS. The first documented SIS advance of Weichselian age reached the study area around 22±2 ka. There is no evidence of a pre-LGM ice advance during the Weichselian in the study area. Within the frame of this project, in addition, the glaciotectonic complex of Jasmund has been studied and its relation to the morphology of the peninsula. The landform of sub-parallel ridges and elongated valleys corresponds to the internal structure of the small-scale fold and thrust belt, which includes detachment folds, fault propagation folds, and fault bend folds with hanging-wall anticlines and footwall synclines. Sediment-landform associations and flow-direction criteria derived from a variety of glacial deposits have been used to reconstruct successive glacial advances and retreats of the ice sheet. In particular, subglacial tills have been studied micro-morphologically by means of a three-dimensional analysis based on the microstructural mapping methodology. The subglacial tills preserved a cross-cutting pattern of microstructural domains that display a temporal succession of deformation events. Based on the orientation and the age relationship of the identified microfabric domains, we developed a 3D model imaging the polyphase deformation pattern produced by the ice at the glacier bed, which is obviously related to the regional ice-flow direction in the studied area. For the first time, the age of the Eemian marine transgression has been documented by means of pollen and ostracod assemblages from the cliff section of Klein Klütz Höved. The transgression occurred about 300 to 750 years after the onset of the Eemian.
Publications
- Luminescence dating of Weichselian interstadial sediments from the German Baltic Sea coast. – Quaternary Geochronology 30: 251-256
Kenzler, M., Tsukamoto, S., Meng, S., Thiel, C., Frechen, M. & Hüneke, H.
(See online at https://doi.org/10.1016/j.quageo.2015.05.015) - Three-dimensional microfabric analysis of Pleistocene tills from the cliff section Dwasieden on Rügen (Baltic Sea coast): micromorphological evidence for subglacial polyphase deformation – PhD dissertation, University of Greifswald. 1-237
Brumme, J.
- 3D microstructural architecture of deformed glacigenic sediments associated with large-scale glacitectonism, Jasmund Peninsula (NE Rügen), Germany. – Journal of Quaternary Science 32: 213-230
Gehrmann, A., Hüneke, H., Meschede, M., Phillips, E.
(See online at https://doi.org/10.1002/jqs.2843) - A multi-proxy palaeoenvironmental and geochronological reconstruction of the Saalian-Eemian-Weichselian succession at Klein Klütz Höved, NE Germany. – Boreas
Kenzler, M., Rother, H., Hüneke, H., Frenzel, P., Strahl, J., Tsukamoto, S., Li, Y., Meng, S., Gallas, J., Frechen, M.
(See online at https://doi.org/10.1111/bor.12255) - Ice-sheet dynamics and climate fluctuations during the Weichselian glaciation along the southwestern Baltic Sea coast. – PhD dissertation, University of Greifswald. 1-169
Kenzler, M.
- New age constraints from the SW Baltic Sea area - implications for Scandinavian Ice Sheet dynamics and palaeo-environmental conditions during MIS 3 and early MIS 2. – Boreas 46: 34-52
Kenzler, M., Tsukamoto, S., Meng, S., Frechen, M. & Hüneke, H.
(See online at https://doi.org/10.1111/bor.12206) - Evidence from seismites for glacio-isostatically induced crustal faulting in front of an advancing land-ice mass (Rügen Island, SW Baltic Sea). Tectonophysics, Vol. 745. 2018, pp. 338-348.
Pisarska-Jamroży, M., Belzyt, S., Börner, A., Hoffmann, G., Hüneke, H., Kenzler, M., Obst, K., Rother, H., van Loon, A.J.
(See online at https://doi.org/10.1016/j.tecto.2018.08.004)
