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| Titel |
Geophysical characterisation of Subglacial Lake Ellsworth, West Antarctica |
| VerfasserIn |
N. Ross, A. M. Smith, J. Woodward, M. J. Siegert, H. F. J. Corr, E. C. King, R. C. A. Hindmarsh, D. G. Vaughan |
| Konferenz |
EGU General Assembly 2009
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 11 (2009) |
| Datensatznummer |
250019825
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| Zusammenfassung |
| Subglacial Lake Ellsworth (SLE) is believed to represent the most appropriate target for
direct sampling of a subglacial lake in West Antarctica. A comprehensive geophysical
characterisation of SLE and its surrounding subglacial environments has recently been
undertaken, with a core objective identifying the best location for direct measurement and
sampling of the lake waters and underlying sediments.
Radar-derived basal topographic data show that SLE is located within one of a series of deep,
fjord-like valleys at the margin of the Ellsworth Subglacial Highlands. At 3-3.25 km beneath
the ice surface, SLE is 11.9 km long, is 3 km wide at its maximum point and has a surface
area of approximately 21.5 m2. A potential overspill channel for water draining from the
downstream end of SLE has been identified in one radar profile. This low-lying gap in the
topography may provide a subglacial hydrological pathway from SLE to a second lake
downstream.
The geometry of the SLE water cavity has been established from five seismic reflection
profiles, all orientated perpendicular to the long axis of the lake. The aims of the seismic
surveys were to determine the lake bathymetry and to give some indication of both the
physical conditions within the lake, and the nature and structure of any sediments at the lake
floor. The seismic data confirm that SLE is a substantial water-body, with a maximum water
column thickness of 155 m. These data have been combined with radar measurements of ice
thickness and used to constrain 3D models of the lake’s ice-water interface and the bed of the
lake. Analysis of the seismic data suggests that the lake floor is characterised by
high-porosity, low-density sediments indicative of accumulation in a low-energy
depositional setting. The evidence for a deep water-body, underlain by a sedimentary
package, confirms that SLE is an ideal candidate for direct measurement and sampling. |
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