1 research outputs found
Palaeogeographical changes in response to glacialâinterglacial cycles, as recorded in Middle and Late Pleistocene seismic stratigraphy, southern North Sea
Offshore stratigraphic records from the North Sea contain information to reconstruct palaeoâiceâsheet extent and understand sedimentary processes and landscape response to Pleistocene glacialâinterglacial cycles. We document three major Middle to Late Pleistocene stratigraphic packages over a 401âkm2 area (Norfolk Vanguard/Boreas Offshore Wind Farm), offshore East Anglia, UK, through the integration of 2D seismic, borehole and cone penetration test data. The lowermost unit is predominantly fluviatile [Yarmouth Roads Formation, Marine Isotope Stage (MIS) 19â13], including three northwardâdraining valleys. The middle unit (Swarte Bank Formation) records the southernmost extent of tunnel valleyâfills in this area of the North Sea, providing evidence for subglacial conditions most likely during the Anglian stage (MIS 12) glaciation. The Yarmouth Roads and Swarte Bank deposits are truncated and overlain by lowâenergy estuarine silts and clays (Brown Bank Formation; MIS 5dâ4). Smaller scale features, including duneâscale bedforms, and abrupt changes in cone penetration test parameters, provide evidence for episodic changes in relative sea level within MIS 5. The landscape evolution recorded in deposits of ~MIS 19â5 are strongly related to glacialâinterglacial cycles, although a distinctive aspect of this lowârelief iceâmarginal setting are opposing sediment transport directions under contrasting sedimentary process regimes