Ice fabric evolution process understood from anisotropic distribution of a-axis orientation on the GRIP (Greenland) ice core
Authors: Miyamoto, Atsushi; Shoji, Hitoshi; Hori, Akira; Hondoh, Takeo; Clausen, Henrik B.; Watanabe, Okitsugu
Source: Annals of Glaciology, Volume 42, Number 1, August 2005 , pp. 47-52(6)
Publisher: International Glaciological Society
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Abstract:
To better understand how ice fabric evolves in polar ice sheets, we use X-ray diffraction to measure ice crystal orientations. X-ray measurement equipment which can measure the orientation of the c axis and a axis of each crystal in a thin section with high measurement accuracy was developed. In this study, we present a-axes orientation distribution of the deep part of the GRIP (Greenland summit) ice core. At some depths, we find an anisotropic distribution of a-axes orientation. Long-term uniaxial compression tests are also carried out on the GRIP ice core to investigate the ice fabric evolution process. The c-axis orientation distribution develops into a stronger single maximum as the strain increases up to about 20% strain. We find that the a axes of each grain also tend to cluster close to nearly a mutual direction. We discuss the development process of ice fabrics, taking into consideration the distribution of the a-axis orientations. It is suggested that these fabrics may be attributed to a local simple shear deformation in the deep part of an ice sheet.Document Type: Research article
DOI: 10.3189/172756405781812501
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