Strain in the ice sheet deduced from the crystal-orientation fabrics from bare icefields adjacent to the Sør-Rondane Mountains, Dronning Maud Land, East Antarctica

Abstract

Structural analyses of ice collected from the bare ice surface in the region of the Sør-Rondane Mountains were carried out. Crystal-orientation fabrics and the disposition of surface cracks were investigated to determine the stress/strain configuration in the ice sheet near the mountains. Single-maximum fabric patterns with the axis of the maximum roughly perpendicular to the flow line on the horizontal plane were observed. It was deduced from the observations that the ice exhibits a fabric pattern indicating that the ice sheet is subjected to vertical shear strain between the ice flow and the nunataks.

Radar Characterization of Ice Crystal Orientation Fabric and Anisotropic Viscosity Within an Antarctic Ice Stream

“…Matsuoka et al, 2012). However, deviations from the simple relationship between compression and c-axis alignment are predicted for ice undergoing simple shear (Fujita & Mae, 1994;Llorens et al, 2016), which are supported by laboratory experiments (Qi et al, 2019). Specifically, for the case of an ideal horizontal pole, the c-axes are predicted to migrate toward being perpendicular to the shear plane due to an additional rigid body rotation, which results in fabric orientation deviating by 45° from the principal compression angle for the case of infinite strain (Fujita & Mae, 1994).…”

“…Notably, Transect A illustrates that the principal compression direction and fabric orientation both azimuthally rotate away from the flow direction (approaching 35° relative to ice flow near the ice-stream margin, Figure 9a). Transect A therefore illustrates that the predicted deviation from alignment with compression due to rigid body rotation (Azuma & Higashi, 1985;Fujita & Mae, 1994) is relatively small in the shallowest ice layer near the shear margin. An explanation for this discrepancy is that the shallow-ice fabric in U1 is in a transient state and still developing with ice depth.…”

Using radar-sounding data to identify the distribution and sources of subglacial water: application to Dome C, East Antarctica

“…Tracking and dating internal layers nternal layers in ice-penetrating radar data can result from density contrasts, ice fabric boundaries or changes in ice chemistry (Fujita and Mae, 1994). In this study we consider only layers resulting from chemical boundaries, as they represent constant time horizons (isochrones) resulting from the widespread deposition of electrically conductive aerosols from distant volcanic eruptions.…”