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Ice-sheet flow conditions deduced from mechanical tests of ice core

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningfagfællebedømt

  • Atsushi Miyamoto
  • Hideki Narita
  • Takeo Hondoh
  • Hitoshi Shoji
  • Kunio Kawada
  • Okitsugu Watanabe
  • Dahl-Jensen, Dorthe
  • Niels Steen Gundestrup
  • Henrik Brink Clausen
  • Paul Duval
Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate (type A) and constant load (type B). Fifty-four uniaxial-compression test specimens from 1327-2922 m were selected. Each test specimen (25 mm × 25 mm × 90 mm) was prepared with its uniaxial stress axis inclined 45° from the core axis in order to examine the flow behavior of strong single-maximum ice-core samples with basal planes parallel to the horizontal plane of the ice sheet. The ice-flow enhancement factors show a gradual increase with depth down to approximately 2000 m. These results can be interpreted in terms of an increase in the fourth-order Schmid factor. Below 2000 m depth, the flow-enhancement factor increases to about 20-30 with a relatively high variability. When the Schmid factor was > 0.46, the enhancement factor obtained was higher than expected from the c-axis concentrations measured. The higher values of flow-enhancement factor were obtained from specimens with a cloudy band structure. It was revealed that cloudy bands affect ice-deformation processes, but the details remain unclear.
Udgivelsesdato: June
OriginalsprogEngelsk
TidsskriftAnnals of Glaciology
Vol/bind29
Udgave nummer1
Sider (fra-til)179-183
ISSN0260-3055
DOI
StatusUdgivet - 1999

ID: 187070