@article{oai:nipr.repo.nii.ac.jp:00003990, author = {ショウジ, ヒトシ and ミヤモト, アツシ and ナリタ, ヒデキ and SHOJI, Hitoshi and MIYAMOTO, Atsushi and NARITA, Hideki}, journal = {Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology}, month = {Nov}, note = {P(論文), Flow behavior of large ice sheets is affected mainly by c-axis orientation fabric, and the fabric formation is caused by the anisotropic characteristics in the plastic deformation property of ice crystal. There are three processes involved in fabric formation; i.e. crystal rotation (AZUMA and HIGASHI, 1985), recrystalization and polygonization. Two types of crystal fabric development with depth have been observed in deep polar ice cores. Type A shows crystal fabric changes from a random distribution near the surface to vertical cluster development with depth under vertical compression and to a strong single maximum pattern near the bottom under simple shear deformation (Camp Century, Dye 3,GRIP and Byrd ice cores). Type B shows fabric changes from a random distribution near the surface to a large girdle development with depth, where the c-axis direction is almost perpendicular to the uniaxial tensile strain axis along the ice flow direction (Mizuho and Vostok ice cores). To estimate vertical compressive strain, ε and uniaxial tensile strain, γ, the following equations were assumed : ε=-ln(y/H), γ=-2ln(y/H), where y is height from the bottom and H is ice thickness. For Type A cores, the c-axis lies mainly along the vertical core direction with depth and a single maximum fabric appears at depth for about ε=150%, except for Byrd core samples which shows single maximum fabric appearance for about ε=80%. For Type B cores, crystal fabrics developments with an increase in γ are quite similar to each other.}, title = {ICE CRYSTAL ORIENTATION DISTRIBUTIONS IN LARGE ICE MASSES}, volume = {11}, year = {1997} }