Depositional environments and chronology of Late Weichselian glaciation and deglaciation in the central North Sea

• Published in: Boreas
• Main Authors: GRAHAM, ALASTAIR G. C., LONERGAN, LIDIA, STOKER, MARTYN S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2010
• Subjects: Geology; Archeology; Ecology, Evolution, Behavior and Systematics; Fennoscandian; Ice Sheet
• Online Access: http://dx.doi.org/10.1111/j.1502-3885.2010.00144.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1502-3885.2010.00144.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1502-3885.2010.00144.x

Graham, A.G.C., Lonergan, L. & Stoker, M.S. 2010: Depositional environments and chronology of Late Weichselian glaciation and deglaciation in the central North Sea. Boreas , Vol. 39, pp. 471–491. 10.1111/j.1502‐3885.2010.00144.x. ISSN 0300‐9483. Geological constraints on ice‐sheet deglaciation are essential for improving the modelling of ice masses and understanding their potential for future change. Here, we present a detailed interpretation of depositional environments from a new 30‐m‐long borehole in the central North Sea, with the aim of improving constraints on the history of the marine Late Pleistocene British–Fennoscandian Ice Sheet. Seven units characterize a sequence of compacted and distorted glaciomarine diamictons, which are overlain by interbedded glaciomarine diamictons and soft, bedded to homogeneous marine muds. Through correlation of borehole and 2D/3D seismic observations, we identify three palaeoregimes. These are: a period of advance and ice‐sheet overriding; a phase of deglaciation; and a phase of postglacial glaciomarine‐to‐marine sedimentation. Deformed subglacial sediments correlate with a buried suite of streamlined subglacial bedforms, and indicate overriding by the SE–NW‐flowing Witch Ground ice stream. AMS 14 C dating confirms ice‐stream activity and extensive glaciation of the North Sea during the Last Glacial Maximum, between c . 30 and 16.2 14 C ka BP. Sediments overlying the ice‐compacted deposits have been reworked, but can be used to constrain initial deglaciation to no later than 16.2 14 C ka BP. A re‐advance of British ice during the last deglaciation, dated at 13.9 14 C ka BP, delivered ice‐proximal deposits to the core site and deposited glaciomarine sediments rapidly during the subsequent retreat. A transition to more temperate marine conditions is clear in lithostratigraphic and seismic records, marked by a regionally pervasive iceberg‐ploughmarked erosion surface. The iceberg discharges that formed this horizon are dated to between 13.9 and 12 14 C ka BP, and may ...