The Quaternary evolution of the mid-Norwegian continental margin
In this thesis, high-resolution two- and three-dimensional seismic reflection datasets are used to examine the Quaternary Naust Formation on the mid-Norwegian continental shelf and slope, both at a high level of detail and over a huge areal extent of over 150,000 km2. First, the analysis of broad-sc...
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| Format: | Doctoral or Postdoctoral Thesis |
| Language: | English |
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Darwin
2019
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| Online Access: | https://doi.org/10.17863/CAM.44971 https://www.repository.cam.ac.uk/handle/1810/297917 |
| Summary: | In this thesis, high-resolution two- and three-dimensional seismic reflection datasets are used to examine the Quaternary Naust Formation on the mid-Norwegian continental shelf and slope, both at a high level of detail and over a huge areal extent of over 150,000 km2. First, the analysis of broad-scale margin architecture demonstrates the gradual development and increase in number of cross-shelf troughs produced by past ice streams that periodically drained the growing and decaying Fennoscandian Ice Sheet since approximately 1.5 M.y. ago. The development and intensification of focused ice flow from about 0.8 M.y. ago resulted in enhanced erosion on the shelf and increased sediment flux to the adjacent continental slope, with rapid shelf edge progradation and associated changes in margin architecture. The structural high of the Vøring Plateau, characterised by initially low (1-2º) slope gradients and reduced accommodation space, exerted a strong control over the long-term architectural evolution of the margin. Slope sediment fluxes were higher in the Vøring Plateau area, having increased up to 32 km3 k.y.−1 over the Quaternary compared to the maximum of 7 km3 k.y.−1 in the neighbouring sectors of the slope, which were characterised by steeper gradients (3-5º), more available accommodation space and smaller or no palaeo-ice streams on the adjacent shelves. Second, submarine glacial landforms found on the 500-km long mid-Norwegian continental shelf allow the reconstruction of the ice-sheet configuration over several Quaternary glacial–interglacial cycles. Evidence of iceberg ploughmarks found within the earliest Quaternary Naust surfaces documents a marine-terminating, calving Fennoscandian Ice Sheet margin extending periodically onto the mid-Norwegian shelf since the earliest Quaternary. Buried subglacially-produced mega-scale glacial lineations and ice-marginal grounding-zone landforms show the changing locations of fast-flowing ice streams as well as areas of slow-flowing ice, indicating dynamic ice-sheet ... |
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