Crystallographic Preferred Orientation Data for Ice Deformed Via Grain Size Sensitive Creep

Laboratory experiments were performed on samples of deuterated water ice with grain sizes <30 microns. Samples were deformed via a grain size sensitive creep mechanism, so-called superplastic flow, in which basal dislocation slip and grain boundary sliding are mutual accommodating deformation processes. This mechanism is likely rate controlling during deformation of glaciers and ice sheets. Samples were also deformed via grain size insensitive creep (i.e., dislocation creep). Crystallographic preferred orientations of grains within deformed and undeformed samples were determined via neutron diffraction. The resulting texture data show little to no c-axis fabric for samples deformed via superplastic flow to relatively small uniaxial strains up to 20%, and classic single maximum c-axis patterns for samples deformed via dislocation creep to strains of ~35%. C-axis fabrics for samples deformed to larger strains (up to 80% in uniaxial compression)are currently being analyzed.