Rezultaty
A milestone to be reported is the progress made in understanding the (de-)glacial water mass circulation patterns in the Faeroe-Shetland gateway, which is crucial with respect to water-mass exchange between the Nordic Seas and the North Atlantic Basin. The extreme sedimentation flux during deglaciation on the Northern Margins is resulting from a combination of a rapid sea-level rise, constantly exposing new areas for marine erosion/winnowing, and vigorous surface ocean current activity. The studies reveal that the shifts in the style of sedimentation are directly linked to the rapid reorganisations of the ocean surface circulation along the northern European Atlantic Margin.
With the information from high-resolution bathymetry, deep tow side-scan sonar, seismic subbottom profiles and subsequent sediment coring, sediment mass-flow dynamics on the Celtic Margin, the Faeroe Margin, and the Norwegian Margin were identified. A new insight into the existence of stable and unstable environments in deep-water continental slope settings was achieved. This is particularly important for the hydrocarbon industry, which is moving with their exploration activity to deep-water environments. Therefore, cooperation with the SEABED project, a consortium of the hydrocarbon industry encompassing 8 European oil companies was achieved. This is presently enlarged with the 4 JIP's (Joint Industry Projects) involving 27 oil companies.
The identification of five mega-slides in the southeastern Norwegian Sea region through the 1.1myr (including the Storegga Slide) has contributed to the understanding of the role such processes play in the development of the margin. For the last of these events a new phase of detailed investigations were initiated when the TOBI side-scan sonar data collected in 1997. These provided spectacular pictures of the sediment slide areas and different processes linked with sediment mass wasting.
Focusing on slope instability of the Faeroes margin, the milestones are:
1) The finding of an area of late Quaternary slump deposits on the western slope of the Faeroe-Shetland Channel.
2) The timing of repeated late Quaternary mass-flow activity on the margin north-east of the Faeroe Islands. Until recently, no documentation was available showing the existence of larger surficial slumps or slides on the Faeroes slope of the Faeroe-Shetland Channel. There is a long distance sediment transport from the original mass-flow area in a southerly (downstream) direction due to a strong (interglacial) flow of Norwegian Sea Overflow Water (NSOW).
The Celtic margin constituted the "non glaciated" end member of the European North Atlantic Margin sites. An acoustic imagery of the Celtic Deep Sea Fan allowed for the first time to identify its morphological characteristics into three main physiographical areas. The upper fan is characterised by two main tributary channels: the Whittard Channel to the west, and the Shamrock Channel to the east. The upper-middle fan boundary corresponds to the disappearance of the "channel-levee" systems and the appearance of lobe deposits. The middle and lower fan include only secondary channels and their related lobes.
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