A mid-Oligocene cooling (Oi-2b) reflected in the dinoflagellate record and in depositional sequence architecture. An integrated study from the eastern North Sea Basin

One of the surfaces studied on 3D seismic datasets shows features such as low-angle landward directed onlaps, incised valleys and pockmarks, indicating a prominent, relative sea-level fall. The cold-water dinoflagellate Svalbardella was recorded immediately above this surface. The coincidence of a cold-water indicator with this distinctive sequence boundary shows that deposition of this sequence was controlled by climatically induced sea-level changes, and that 3D seismic analysis combined with high-resolution dinoflagellate analysis substantially improves the understanding of the depositional history and processes within the North Sea Basin. The Svalbardella event represents the Oi-2b glaciation and coincides with the onshore NW European Rupelian/Chattian boundary.