Late surge glacial conditions on Bakaninbreen, Svalbard, and implications for surge termination

A. M. Smith*, T. Murray, B. M. Davison, A. F. Clough, J. Woodward, H. Jiskoot

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

25 Citations (Scopus)

Abstract

Bakaninbreen is a polythermal glacier in southern Spitsbergen, Svalbard, that last surged between 1985 and 1995. Seismic reflection data were acquired during early quiescence in spring 1998, just upstream of the surge front. The results were combined with complementary ground-penetrating radar data to investigate the glacial structure and basal conditions. We find no difference between the ice thickness values determined from the seismic and radar methods, suggesting that any layer of basal ice cannot be greater than ∼5 m thick. Interpretation of the amplitude of the seismic reflections indicates the presence of permafrost close to the glacier base. A thin layer of thawed deforming sediment separates the glacier from this underlying permafrost. In an area just upstream of the surge front the permafrost becomes discontinuous and may even be absent, the ice being underlain by 10-15 m of thawed sediments overlying deeper bedrock. High-pressure water is believed to have been required to maintain the propagation of the surge, and this area of thawed sediment is interpreted as a route for that water to escape from the basal system. When the surge front passed over this thawed bed, the escaping water reduced the pressure in the subglacial hydraulic system, initiating the termination of the surge. Surge termination was therefore primarily controlled by the presurge permafrost distribution beneath the glacier, rather than any feature of the surge itself. This termination mechanism is probably limited to surges in polythermal glaciers, but the techniques used may have wider glaciological applications.

Original languageEnglish
Pages (from-to)ESE 1-1 - 1-16
Number of pages16
JournalJournal of Geophysical Research: Solid Earth
Volume107
Issue number8
Early online date6 Aug 2002
DOIs
Publication statusPublished - Aug 2002
Externally publishedYes

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