PhD Research

Submarine mass movement processes, driven by gravitational forces, represent an important mechanism whereby vast amounts of sediment are rapidly transported downslope and redistributed into deep-water from an originally shallow-water setting, and their deposits are widely recognised in continental margins. Although there is a tendency to consider these processes independently, there is an increasing awareness that in many cases these processes need to be integrated to produce a model of margin development. The mass movement processes display large temporal and spatial variations and have different importance, but their interrelationship needs to be understood and background sedimentation processes must be considered. Increasing knowledge of mass movement processes on the continental slope also has interest for natural hazard assessment.

The scale and diversity of mass movement processes that shaped the glaciated NW European margin, combined with the extensive geophysical and geological datasets from the area, many acquired by the exploration industry, makes it an excellent area to study the interrelationship of mass movements. This margin has been affected by recurrent climate-related episodes of growth and retreat of ice sheet, which covered entirely Scandinavia and part of the UK during the Quaternary (Sejrup et al., 2000). In each glacial episode, ice advanced onto the continental shelf and on some occasions reached the shelf break delivering directly sediments to the upper continental slope. Although today there are no areas where glacier ice is grounded at the shelf edge, the evidence of the past ice sheet activity is still visible in the seabed morphology, both on the shelf and the slope, as the topography has remained nearly unchanged since the last ice sheet retreat approximately 15 ka BP (Dahlgren et al., 2002). The glaciated European margin has also experienced widespread submarine landslides in the past 1 Ma, and is the location of one of the world largest landslides, the Storegga Slide - with a total of to 3200 km³ of sediments displaced (Haflidason, Haflidi et al., 2004).

The Glaciated European margin is characterized by trough-mouth fans (TMFs) and large-scale submarine landslides.The TMFs are composed largely of stacked glacigenic debris flow deposits that were laid down in front of cross-shelf troughs cut by former fast flowing ice streams. There have been several studies looking at the morphology and sedimentary architecture of this glacier-influenced continental margin at a regional scale (Dowdeswell et al., 1998). However, there is still a need to understand better the link, revealed by King et al. (1996) between large-scale mass transport and glacially delivered sediments.

The objective of this project is to provide a contextual view of the mass movement processes operating on one of largest trough-mouth fans on the glaciated NW European margin, the North Sea Fan, by the integration of large-scale detailed geomorphological mapping with seismic stratigraphy. However, like most geological analytical tools, it is the products of geological processes that are revealed by these data rather than the processes themselves; it is necessary therefore, to infer the processes. The detailed mapping of the morphological elements of the North Sea Fan area will be based on high-quality acoustic datasets, including 3D seismic reflection, acquired through cooperation between academia and the petroleum industry.

Apart from the practical benefit of showing how 3D seismic can be used to detail geomorphological characterization and adapt geomorphometric techniques, it is expected that this project will reveal interesting observations that will provide a better comprehension of the emplacement and the inter-actions between large-scale slides and debris flows on trough-mouth fans. This will contribute to the understanding of the interrelationship between mass transport processes and Cenozoic evolution of the glaciated margin, by studying an aspect of the critical link between shallow-water and deep-water sedimentary environments.