In Lower Saxony, the base Quaternary shows a diverse relief, largely due to the complex network of buried tunnel valleys, which are primarily associated with the Elsterian glacial stage. They cut into underlying Tertiary sediments. Incision depths range from a few tens of meters to 400 meters. The tunnel valleys may host minable sand and gravel deposits and groundwater reservoirs. They can help to predict the erosion depth of future glaciations, which is an important constraint for the storage of radioactive waste. Thus, a comprehensive up-to-date geological 3D model of the base Quaternary is crucial to support strategies in sustainable resource extraction and land use.
The new Lower Saxony 3D model is compiled in SKUA-GOCAD™ (AspenTech) and is based on a broad dataset. The existing contour map of the base Quaternary is combined with more recent data, e.g. regional 3D models and extensive borehole data. The use of seismic data (2D/3D) has been particularly effective for mapping tunnel valleys as it enables a spatially inclusive representation of these structures. In the current model region (northwest Lower Saxony), several previously unknown tunnel valleys were discovered, reaching depths of up to -200 m NHN. The depth of known subglacial channels was adjusted up to 250 m compared to the previous contour map. Following the completion of the first sub-region, we anticipate that the base Quaternary will reveal significantly deeper tunnel valleys in the new 3D model across the majority of Lower Saxony.