The infill of tunnel valleys in the central North Sea: Implications for sedimentary processes, geohazards, and ice-sheet dynamics

• DOI: 10.1016/j.margeo.2023.107185
• Publication Date: 2023-11-25T16:11:33Z
• Authors: James D. Kirkham; Kelly A. Hogan; Robert D. Larter; Ed Self; Ken Games; Mads Huuse; Margaret A. Stewart; Dag Ottesen; Daniel P. Le Heron; Alex Lawrence; Ian Kane; Neil S. Arnold; Julian A. Dowdeswell
• Keywords: Deglaciation; Infill; Landform; Seafloor Spreading

Tunnel valleys are widespread in formerly glaciated regions such as the North Sea and record sediment transport beneath ice sheets undergoing deglaciation. However, their complex infill architecture often makes implications for ice-sheet processes difficult to unravel. Here, we use high resolution 3D (HR3D) seismic data, improved-resolution conventional seismic-reflection geotechnical information from industry-acquired boreholes image of buried Quaternary tunnel unprecedented detail. Ten cross-cutting generations mapped seafloor where only seven were visible previously. Each generation potentially reflects a different glaciation, although our evidence may imply that it is possible rapidly erode multiple within single glacial cycle. The oldest valley sedimentation during relatively gradual retreat, with occasional episodes overriding by re-advancing grounded ice. formed more recent glaciations characterised variable patterns reflect dynamic fluctuations margin, including readvances stagnation, filling retreat. Numerous subglacial landforms also imaged valleys; these sometimes contain shallow gas accumulations represent geohazards installations. In addition, document examples salt diapirism has caused fluids migrate upwards depth through faults into near-surface valleys. instances this occurs, porous highly continuous present allow spread laterally kilometres or even escape seafloor; therefore important consider when monitoring CO2 leakage carbon capture storage efforts.