Formation Processes of Ice Fabric Pattern in Ice Sheets

Abstract

Experimental studies on the Formation process of the single maximum fabric of ice from its random fabric were carried out using both Greenland Dye-3 ice cores and artificially grown polycrystalline ice. From the observations of the rotation of c-axes of individual grains in thin specimens, an empirical equation was obtained for describing the rotation process of c-axes. Combined with another empirical equation on the relationship between the uniaxial strain of whole specimen and the uniaxial strain in individual grains of different c-axis direction, an equation was derived which describes the formation of single maximum fabric in bulk ice samples.Computer simulation of the formation process was performed based on an equation starting from an artificially made random fabric pattern. From the results obtained by a stepwise simulation of 2% strain intervals, the degree of concentration expressed by θm, the angle which halves the number of grains in the fabric diagram is correlated with the accumulated strain in bulk ice (Fig. 8). The strain deduced by applying this relationship to the obtained θm for samples of Dye-3 ice core coincided well with actual strain which the samples had experienced. This implies that the equation is valid and the mechanism of c-axis rotation prevails in polar ice sheets.