Dating DK: Cosmogenic 10Be depth profiling of glacial outwash plains in Denmark

During the Quaternary period the Fennoscandian ice sheet reached far into Europe on several occasions. Especially the last two ice sheet expansions, the Saalian and Weichselian, left many marks on the Danish land surface and shaped the landscape, leaving behind outwash plains, terminal moraines, tunnel valleys, and other glacial landforms. Although, there is general consensus regarding which ice advances resulted in which landscape features, most correlations have not yet been verified by absolute dating. To improve constraints on the ice cover history of the Danish area, we have carried out ¹⁰Be profiling on several outwash plains across Denmark. These outwash plains have been chosen (i) to constrain the timing of the overall ice margin retreat across Denmark, and (ii) to decipher whether the northern part of the prominent 90-degree landform (the “Main Stationary line”) belongs to the Last Glacial Maximum advance (~20.000 years ago) or a previous ice advance, such as the Kattegat advance (~30.000 years ago). Denmark is located right at the foothills of the Fennoscandian ice sheet, and we expect our results to have strong implications on the understanding of ice sheet dynamics at play during advance-retreat cycles of continental sized ice sheets, as well as to improve the understanding of the glacial history of Northern Europe. At EGU some of the preliminary results from this investigation will be presented.

¹⁰Be profiling is a technique which involves sampling sediment from several depths below the surface at a specific location. Interpretation of the ¹⁰Be concentrations can lead to age estimation of the sampled deposit, since the concentrations will depend on the cosmogenic exposure history of the sediment package. A set of samples from different depths are needed to separate the pre- and post-burial ¹⁰Be nuclide concentrations or to draw attention to ¹⁰Be irregularities throughout the profile indicating asynchronous deposition. The numerical modelling of nuclide concentrations carried out in this study serves as proof of concept and highlights the applicability of the ¹⁰Be profiling approach. Hence, alongside the preliminary results of the study, our novel MATLAB implementations for interpreting ¹⁰Be profiles will also be showcased.