RATE CONTROLLING PROCESSES IN THE CREEP OF POLAR GLACIER ICE

• Main Authors: Pimienta, P., Duval, P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 1987
• Subjects: [PHYS.HIST]Physics [physics]/Physics archives; South Pole; Dye 3; Dye-3; ice core; South pole
• Online Access: https://hal.science/jpa-00226280; https://hal.science/jpa-00226280/document; https://hal.science/jpa-00226280/file/ajp-jphyscol198748C134.pdf; https://doi.org/10.1051/jphyscol:1987134

Torsion tests have been carried out on artificial ice and on samples cut from an ice core obtained at South Pole Station. Results give a stress exponent smaller than 2 for stresses lower than 0.1 MPa. Analysis of the inclinometer survey of the Dye 3 borehole yields the same result. The deformation mechanisms of polar ice at low stresses are reviewed. A Newtonian viscosity may be expected with dislocation glide accommodated by grainboundary migration linked with graingrowth. However, rotation of crystals by dislocation glide and strain-induced boundary migration are complementary and efficient mechanisms to accommodate the incompatible plastic deformation between grains of different lattice orientation. These deformation mechanisms concern a great part of polar ice.