Friday, 31 August 2007
5.PS-136
Subglacial conditions at a sticky spot along Kamb Ice Stream, West Antarctica
Leo E. Peters and Sridhar Anandakrishnan. Department of Geosciences, The Pennsylvania State University, State College, PA 16803
<>We present the results of a seismic reflection experiment performed along the trunk of Kamb Ice Stream where we image a basal high surrounded by a bed with variable subglacial conditions. This high rises ~100 m above the surrounding bed, acting as a major sticking point that resists fast ice flow. Application of the amplitude variation with offset (AVO) seismic technique has detected a region of frozen sediments along the profile, suggesting that the ice stream is experiencing basal freeze-on in this region. The bedrock high appears to be at least partially draped in frozen sediment cover, with a concentrated area of basal water flanking one edge. Dilatant till is also present along our profile, though this till does not possess enough continuity to maintain streaming ice conditions. These results support the hypothesis that the ongoing shutdown of Kamb Ice Stream is due to a loss in continuous basal lubrication.