FABRIC OF POLYCRYSTALLINE ICE DEFORMED IN SIMPLE SHEAR: EXPERIMENTS IN TORSION, NATURAL DEFORMATION AND GEOMETRICAL INTERPRETATION.

Abstract

Three cylinders of artificial ice have been deformed in torsion at about minus 10 degree C up to finite shear strains gamma of 0. 6, 0. 95 and 2. The bimodal distribution reflects predominant slip on the basal plane; the progressively increasing heterogeneous strain enhances internal distortion, rigid body rotation and recrystallization of grains unfavorably oriented for further slip, leading to the unimodal distribution. The adequacy of fabric analyses to infer the strain regime and sense of shear in plastically deformed rocks is strengthened.