Glacial processes on the continental shelf of the Amundsen Sea Embayment, West Antarctica
The Amundsen Sea Embayment and Pine Island Bay of Western Antarctica play a key role in understanding past dynamics of the West Antarctic Ice Sheet. Seismic reflection data and corresponding gravimetric data give insights in sedimentary and glacial processes on the middle shelf, the outer shelf and...
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| Format: | Thesis |
| Language: | unknown |
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2011
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| Online Access: | https://epic.awi.de/id/eprint/26053/ https://hdl.handle.net/10013/epic.38980 |
| Summary: | The Amundsen Sea Embayment and Pine Island Bay of Western Antarctica play a key role in understanding past dynamics of the West Antarctic Ice Sheet. Seismic reflection data and corresponding gravimetric data give insights in sedimentary and glacial processes on the middle shelf, the outer shelf and the continental slope of the eastern Amundsen Sea Embayment. The main focus during the seismic processing was the suppression of the multiple energy, masking underlying reflectors. Two techniques of multiple attenuation, F-K filter and Parabolic Radon Transformation, were applied to the data, as well as an Omega-X-Migration. These processing steps resulted in an almost complete suppression of the multiples and improved the visibility of underlying reflectors for the interpretation. On the middle shelf, the Pine Island glacial trough shows a nearly constant position throughout glacial periods. It is embedded in a deep sedimentary basin, which is created by rifting processes, possibly related to the West Antarctic Rift System, at the tectonic block boundary between Marie Byrd Land and the Thurston Island/Ellsworth Land blocks. On the outer shelf and the continental slope, the basement, which shows a distinct NESW-trending high, influences the sedimentation patterns strongly. The Pine Island glacier system advanced over the continental shelf, but sediment transport to the continental slope was limited in earlier glacial cycles by the basement high. After overcoming this barrier the shelf break prograded approximately 80 km northwards, through the built-up of a till fan. The Pine Island glacier system absorbed several medium-sized and smaller ice streams, such as the ice streams of the Abbot Ice Shelf. Outside of the influence of the large Pine Island glacier system, smaller ice streams, such as those originating on Thurston Island advanced to the outer shelf, but did not override the basement high and therefore lead only to shelf aggradation. Overall, the basement plays an important role in the depositional patterns of the eastern Amundsen Sea Embayment by trapping sediments in basins on the middle shelf and controling the sedimentation to the continental slope by basement highs acting as barriers. |
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