Exploring the Outline of the Pre-Odra River System Through Seismic Reflection Imaging Offshore Rügen Island

Understanding the course and dynamics of ancient river systems, such as the pre-Odra, is crucial for unravelling the geological history of regions like the southern Baltic Sea, providing valuable insights into the post-glacial evolution of landscapes and riverine processes. We will present marine reflection seismic and acoustic data from three research cruises on the research vessel ALKOR that allow us to investigate the pre-Odra river system in the southern Baltic Sea. Our analysis focuses on the region off the east coast of the island Rügen. This region corresponds to the suspected location of the pre-Odra river system, which was situated during the post-glacial phase approximately 9,000 - 14,500 years BP off Rügen. The seismic reflection data indicate that the sediment infill of the pre-Odra is charged by shallow gas of presumably biogenic origin. Since the seismic gas indicators correspond with the pre-Odra where its location has been determined by previous geological studies, we use gas lineaments as a proxy for the braided paleo-river bed. This study refines and extends the known fluvial extent of the Odra river system by 60 km, tracing it north towards the Tromper Wiek, indicating its terminus in the Baltic Sea close to eastern to Rügen.