New chronologies for the Middle Pleistocene formations within the southern North Sea

There are few reliable chronological controls for the Middle Pleistocene Formations of the southern North Sea. Offshore Wind Farm developments in this area are providing unparalleled opportunities to map and investigate these deposits, revealing greater complexity than expected. Geotechnical site investigations offer new opportunities to apply scientific dating techniques to establish the absolute chronology of these deposits, rather than relying on traditional biostratigraphic approaches. This paper presents the results of investigations associated with the Hornsea One and Two Offshore Wind Farms, focusing on Middle to early Late Pleistocene Formations within the Inner Silver and Sole Pits. A new protocol for core handling procedures, implemented during geotechnical site investigations, increased access to core material suitable for paired luminescence dating (quartz OSL and K-feldspar pIRIR). The new dates demonstrate that the base of the Sand Hole Formation is late MIS 12 to MIS 11, with the Egmond Ground Formation likely accumulating through MIS 10 to 8. A deposit above the Egmond Ground Formation is shown to be chronologically, lithologically and biostratigraphically equivalent to the Brown Bank Formation, traditionally found only in the eastern southern North Sea and securely dated to late MIS 5a/early MIS 4. The new absolute dates provide much-needed clarity on the age of Middle Pleistocene Formations in this region and support revision of the existing chronostratigraphy for the southern North Sea.