Early sketches for a detailed nationwide 3D geological model based on geophysical data and boreholes

During the last 15 years a huge geophysical groundwater mapping project covering almost 40 % of Denmark has led to a radical improvement in the geological understanding of the uppermost 300 m. The objective of this mapping is to produce detailed groundwater vulnerability maps and to get an overview of aquifer localization and interconnection. Detailed mapping requires spatially dense geophysical data combined with geological information from new boreholes. The spatial data coverage is obtained by using the SkyTEM system, while high resolution seismic profiling is acquired along selected transects. The result is 3D resistivity volumes geologically interpreted and modeled with support from the seismic data and stratigraphic and lithological information from boreholes. A new detailed stratigraphic framework for the Miocene, hitherto unknown buried tunnel valley systems and subsurface glaciotectonic complexes constitute examples of the new knowledge that has led to revision of old maps, models and interpretations. In order to handle this new geological knowledge and to be able to extract useful, targeted and updated geological information at any time a nationwide 3D geological model is planned to be constructed over the coming years.