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| Titel |
Engacial Seismic Reflectivity - Imaging Crystal Orientation Fabric in West Antarctica |
| VerfasserIn |
Huw Horgan, Sridhar Anandakrishnan, Richard Alley |
| Konferenz |
EGU General Assembly 2011
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250045586
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| Zusammenfassung |
| Active-source seismic observations from West Antarctica offer insight into the evolution of
Crystal Orientation Fabric (COF) within ice-sheets. We observe abrupt changes in COF in
seismic data acquired at WAIS Divide, mid-stream and down-stream on Thwaites Glacier,
and the onset region of Bindschadler Ice Stream. These data reveal a prevalence of englacial
seismic-reflectivity in the bottom quarter of the ice sheet. We determine the origin of the
reflectivity to be abrupt changes in the COF of ice. We base this on the following: i) seismic
character is in keeping with current knowledge of COF within ice sheets, ii) COF
requires the simplest genesis, especially at ice divides, and iii) amplitude analysis
shows that all the reflectivity can be explained by contrasts in seismic velocity
due to COF changes. The observed englacial seismic-reflectivity is complex but
largely bed-conformable. Where prominent bed features are observed, distinctive
englacial structures are also observed. We note that the increase in the quantity
and complexity of COF observations indicates that direct observations of COF at
ice divides likely underestimates the role that fabric plays in ice sheet dynamics. |
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