Crystallographic Structure of Polycrystalline Ice
Abstract For several types of polycrystalline ice of different origins, the spatial lattice orientation of each crystal was determined by measurements of both the a- and c -axis orientations. Analyses of the orientations of adjoining crystals showed that a great majority of adjoining crystals may be...
| Published in: | Journal of Glaciology |
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| Main Authors: | , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Cambridge University Press (CUP)
1978
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1017/s0022143000033724 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000033724 |
| Summary: | Abstract For several types of polycrystalline ice of different origins, the spatial lattice orientation of each crystal was determined by measurements of both the a- and c -axis orientations. Analyses of the orientations of adjoining crystals showed that a great majority of adjoining crystals may be in a twinning relation. With special reference to the multi-maximum c -axis preferred-orientation fabric (the so-called “diamond pattern”), which is expected to occupy the largest part of a glacier ice mass, the crystal boundary structure was estimated. The preferred c -axis orientations of this fabric were explained as being the result of coincident oxygen-oxygen lines (hydrogen-bond lines) between adjoining crystals being concentrated in the orientations where seven oxygen-oxygen lines of one single crystal of ice are distributed. From the above result, it was concluded that the multi-maximum fabric is of the polycrystalline structure closest to the structure of a single crystal of ice among all the fabrics found in large ice masses. It is found that the occurrence, in glaciers and ice sheets, of a multi-maximum fabric has a bias to the parts which have undergone a strong shear deformation for a long time. It is thus suggested that plastic deformation of ice with this fabric may be attributed to mechanical twinning due to a strong shear stress. |
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