Pleistocene and early Holocene palaeo-landscapes of the Dogger Bank South Wind Farm Sites

Abstract

A preliminary ground model was prepared for the planned Dogger Bank South Wind Farm Sites in the UK sector of the North Sea. This ground model is based on a geological interpretation of 2D Ultra Ultra High Resolution Seismic (UUHRS) data and geotechnical data. The interpretation results include seismostratigraphic horizons which delineate major soil units. Mapping of these soil units is important for the planning and design of wind turbine locations and inter array cables. Additionally, these horizons reveal (1) multiple generations of buried palaeochannels and (2) evidence for shifting coastlines. The buried palaeochannels have tributaries and contain evidence for the local presence of marshlands (peat beds) beyond the channel margins. These landscapes formed during the Pleistocene and were subsequently flooded when sea level rose as a result of meltwater release from rapidly decaying ice sheets. Locally, thick sequences of early Holocene marine sand deposits show evidence of large-scale clinoforms, which indicate that palaeocoastlines prograded seaward over a distance of up to 20 km during the early Holocene. The top of these clinoforms contain erosion surfaces and gravel lags, indicating sub-aerial exposure of the delta top. This shows that while in general ‘Doggerland’ was rapidly flooded during the early Holocene, there were short periods when the land area expanded.