Experimental work on the effect of pre-existing anisotropy on fabric development in glaciers

Abstract Localization of deformation in ice is known to be important at all scales in deforming glaciers. However, relatively little is known of the significance of shear localization and the influence of fabric development in anisotropic ice at microscopic scales ( c -axis preferred orientation and the inclination of the primary layering in anisotropic ice masses, during both plane strain-compression and combined simple shear-compression, have been examined. A series of creep tests in the temperature range of −5 to −1°C over a range of shortening strains varying from 10 to 40% and compressive stresses ranging from 0 to 0.7 MPa have been undertaken. Significant variations in the strain rate and microstructural development have been observed in the plane strain-compression experiments that reflects the varying orientations of the anisotropy and its relationship to easy-glide directions in the ice mass. In the unconfined combined compression and shear experiments minimum shear stress rates vary between the variously oriented anisotropic ice masses and deviate from the normal power flow law for isotropic ice. Where annealing occurs, such ice masses preserve the pre-existing c -axis fabric and hence may reflect a contribution from both the recrystallized and inherited ice components.