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Seismic Evidence for a Thin Basal Layer at a Second Location on Ice Stream B, Antarctica

Published online by Cambridge University Press:  20 January 2017

D.D. Blankenship ,
S.T. Rooney ,
R.B. Alley  and
C.R. Bentley
D.D. Blankenship
Affiliation:
Geophysical and Polar Research Center, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, WI 53706-1692, U.S.A.
S.T. Rooney
Affiliation:
Geophysical and Polar Research Center, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, WI 53706-1692, U.S.A.
R.B. Alley
Affiliation:
Geophysical and Polar Research Center, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, WI 53706-1692, U.S.A.
C.R. Bentley
Affiliation:
Geophysical and Polar Research Center, University of Wisconsin–Madison, 1215 West Dayton Street, Madison, WI 53706-1692, U.S.A.
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Abstract

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Type
Abstracts of Papers Presented at the Symposium but not Published in this Volume
Information
Annals of Glaciology , Volume 12 , 1989 , pp. 200
Copyright
Copyright © International Glaciological Society 1989

Seismic experiments have shown that a meters thick layer of unconsolidated sediment exists beneath Ice Stream Β at a location that is several hundred kilometers up-stream from the grounding line. In previous work, we have proposed that a “coupling” line exists about 100 km upstream from the grounding line. Above the coupling line, we believe that the dynamic behavior of Ice Stream Β is dominated by deformation within the basal sediment layers and that erosion is taking place at the bottom of this layer. Below the coupling line, we believe that sliding on a lubricating water film becomes increasingly important and that the subglacial sediments are deposited as a delta. Preliminary results from a 30 km seismic profile near the coupling line of Ice Stream Β show a prominent horizontal reflector several meters below the base of the ice; this reflector is underlain by a sequence of reflectors, each with a down-stream dip of about 1%. We believe that the horizontal and dipping reflectors represent, respectively, the topsets and foresets of the hypothesized delta.