Hard X-ray diffraction experiments were performed on monocrystals from the 3623m-long Vostok core. It was found that strain gradients that were associated with the storage of geometrically necessary dislocations appeared to be a general feature of the deformation microstructure. The lattice distortion was related to bending of the basal planes and to torsion of the lattice around the c-axis. The distortion was compatible with the basal dislocations that were generally observed in ice; thus supporting the assumption that deformation was governed by basal slip and accommodated by recrystallization. The dependence of the ice viscosity upon the grain size in sheets was concluded to be compatible with such accommodation.

Lattice Distortion in Ice Crystals from the Vostok Core (Antarctica) Revealed by Hard X-Ray Diffraction - Implication in the Deformation of Ice at Low Stresses. M.Montagnat, P.Duval, P.Bastie, B.Hamelin, V.Y.Lipenkov: Earth and Planetary Science Letters, 2003, 214[1-2], 369-78