A SEISMIC STRATIGRAPHIC ANALYSIS OF LOWER PLEISTOCENE DEPOSITS IN THEWESTERN DANISH SECTOR OF THE NORTH-SEA

The Lower Pleistocene is well preserved in the centre of the North Sea , in contrast to the onshore sedimentary record in Denmark. In the Cen tral Trough area the base of the Quaternary is deeper than 1000 m, and regional subsidence appears to have been uniform throughout the Early and early Middle Pleistocene. Seismic stratigraphic analysis allows s ubdivision of the Lower Pleistocene depositional succession in the wes tern Danish sector into seven subunits. The seismic reflectors boundin g these subunits can be correlated with seismic third-order sequence b oundaries identified and mapped in the Late Tertiary and Pleistocene s uccession in adjacent British and German sectors. The subunits recogni zed in the Danish area may equal these sequences. Structure contour ma ps for five of the boundaries and isopach maps for three of these subu nits show the position of the depocentres in the area. The main Pleist ocene depocentre coincides with the axis of the central North Sea Basi n. In the Early Pleistocene (Tiglian), local depocentres were also pre sent outside this area. The sediments represented by the seismic seque nces in the Dutch, British and German sectors can be related to the de positional basin of a river system draining the northwest-European con tinent. In addition, climatically induced changes in depositional cond itions in the area have affected the sedimentation pattern.