Glacial and postglacial landscape evolution at Dogger Bank since the Last Glacial Maximum

• Main Author: Emery, Andrew Richard
• Format: Thesis
• Language: English
• Published: University of Leeds 2020
• Subjects: Dogger Bank; Ice Sheet
• Online Access: https://etheses.whiterose.ac.uk/27519/; https://etheses.whiterose.ac.uk/27519/1/AREmery_thesis_corrected_clean.pdf

Integrated datasets of shallow seismic reflection profiles, geotechnical logs and sediment samples for offshore windfarms can reveal landscape evolution during changes in past climate, and help understanding of responses to future changes. Dogger Bank, in the southern North Sea, is an ideal site for offshore wind, and the dataset acquired for site investigation used within this thesis reveals the Late Quaternary history of the North Sea. By conducting detailed interpretation of a dense grid of seismic reflection profiles, I developed high-resolution maps of the subsurface, which were correlated to sedimentological data to interpret depositional environments and landscape evolution. A complete record of the transition from glacial, through terrestrial proglacial and paraglacial, to coastal and marine environments is preserved in the sedimentary archive. Ice-marginal dynamics of the Weichselian ice sheet are revealed in buried glacial geomorphology and 30 m-thick proglacial lake-fill sediments. Rapid ice-stream downwasting at c.27 ka was followed by a slower retreat, isolating the lake, before another rapid phase of ice retreat northward, off Dogger Bank, at c.23 ka. This rerouted meltwater supply, and proglacial rivers draining the ice margin emptied. Increased precipitation due to climate warming at c.17 ka reformed a terrestrial drainage network that incised into the glaciogenic sediments. A barrier coastline was present during marine transgression at c.9 ka. Barrier retreat and preservation was controlled by the antecedent topography, with barrier drowning on shallow slopes, and continuous overstepping on steeper slopes. The landscape evolution of Dogger Bank has revealed the role of topography, at different scales, as a long-term control on geomorphic process and location. This thesis has resulted in improved understanding of the subsurface conditions on Dogger Bank, which can improve the economics of wind turbine placement. This study emphasises the importance of subsurface datasets for both future ...