Towards a three-dimensional geological model of the North Sea subsurface

The Geological Survey of the Netherlands is extending the 3D model of the Quaternary record as created for the onshore part of the country to the North Sea realm. Onshore, cores are the most important source of information. Offshore, seismic data are at least equally valuable. A recent pilot study has shown that 2D and 3D seismic data, originally collected for hydrocarbon exploration, are very useful in delineating much shallower stratigraphic units. This is best achieved by interpreting 3D seismic surveys together with high- resolution 2D seismic lines and well data. In the pilot, focus has been on the Oyster Grounds and Silver Well areas in the central part of the Dutch continental shelf. The units modeled thus far include Middle- to Late-Pleistocene strata that have accumulated in the North Sea Basin. The 3D seismic surveys reveal some remarkable, well-preserved sedimentary features that may be difficult to recognize in 2D profiles but are clearly visible in horizontal time slices. Examples include intricate early Holocene tidal-channel systems and striking sets of tunnel valleys formed during multiple glacial episodes. The level of detail provided paleolandscape scholars to reconstruct environmental settings of Mesolithic (mostly Holocene) times.