Talks.cam

Subglacial landscapes: Tunnel valleys in the central and northern North Sea - Senior Scientist - marine and petroleum geology, British Geological Survey
2019-12-05 16:00 - 17:00 UTC | Scott Polar Research Institute, main lecture theatre
Tunnel valleys are km-scale linear landforms formed subglacially and, in the North Sea, found offshore and associated with multiple glaciations by the Quaternary ice-sheets. In this talk, I present the use of seismic reflection and gravity data to map more than a thousand buried tunnel valleys in the central and northern North Sea. The tunnel valleys are generally present from the seabed to depths of around 400 metres, in a study area of 180 000 km2 from 56°N to around 62°N. Buried tunnel valleys are well-imaged in seismic reflection data, particularly in horizontal timeslice in 3D seismic data. In gravity data, the tunnel valleys appear as small scale gravity lows, likely due to their infill being less compacted and potentially more porous than the surroundings.

This talks shows the most extensive study of tunnel valleys in the region to date, with more than 20% of the study area containing buried tunnel valleys, and also finds the longest tunnel valley recorded worldwide, with large meandering tunnel valleys extending for more than 160 km. We also find tunnel valleys further north than previously reported, as well as a number of isolated tunnel valleys extending towards and into the Norwegian Channel. As reported by other works in the region, the apparently extensive networks of buried valleys are found to be comprised of cross-cutting generations and the next step in the puzzle is to link them to ice sheet dynamics.
