Elverhoi, Anders; Solheim, Anders; Butt, Faisal A. (1998): Shelf-to-deep sea episodic sediment transport processes along a glaciated margin; examples from the western Svalbard-Barents Sea margin. Geological Society of America (GSA), Boulder, CO, United States, In: Anonymous, Geological Society of America, 1998 annual meeting, 30 (7), 364, georefid:1999-017338
Abstract:
The western Svalbard-Barents Sea margin is characterised by shallow troughs and associated glacial fans deposited during the last 2. 6 Myr. The lowermost glacial sequence along the margin (ODP site 986) is ca. 350 m thick with an average calculated sedimentation rate of ca. 50 cm/ky. The thickness of the unit combined with its chaotic internal reflections pattern point towards active mass wasting processes originating from high sedimentary input. However, IRD is conspicuously absent in the unit thereby ruling out any major ice advance as a driving mechanism. A mechanism that could explain the high sediment input other than a major glacial advance still remains elusive. The overlying ca. 250 m thick unit consists of numerous debris flows with abundant dropstones and intervening horizons of hemipelagic sediments. The lithology principally consists of diamictons. It is suggested that increased sediment transport across the shelf resulting from glacial advances was responsible for high sediment input to the shelf break. The rapid build-up of sediments at the shelf break led to instability which then triggered debris flows. Hydroplaning beneath the moving sediment layer is believed to be the driving mechanism. This mechanism can transport sediments as debris flows over hundreds of kilometres on very gentle slopes (<1degree). Several lines of evidence suggest that these events were episodic. The varying abundances of dropstones in this interval (core 986) indicates variations in the intensity of glaciations. For debris flows to take place as a continuous phase, extremely high sedimentation rates would be required (ca. 20 cm/yr. based on theoretical considerations). It is unlikely that such high rates can be constantly maintained over longer periods of time. The build-up and subsequent downslope transfer of the sediments along the Svalbard-Barents Sea margin is likely to have been associated with interglacial-glacial cycles.
Coverage:
West: -9.0440 East: 67.0000 North: 81.0000 South: 64.0000
West: NaN East: NaN North: NaN South: NaN
West: NaN East: NaN North: NaN South: NaN
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