Why ice-age ice is sometimes “soft”
Why ice-age ice is sometimes “soft”
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DOI：
10.1016/0165-232x(91)90058-o
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发表时间：
1991-11
影响因子：
4.1
通讯作者：
W. Paterson
中科院分区：
文献类型：
--
作者：
W. Paterson
对末次冰期沉积冰的力学性质、结构、构造和杂质含量的数据进行了回顾。结论如下：（1）氯离子和可能的硫酸根离子，其浓度相对于全新世冰中的高，阻碍了晶界迁移和晶粒生长，因此晶体保持较小。(2)这样的冰，在剪切平行于冰盖床，发展一个强大的，近垂直的，单一的最大结构。(3)这种织物有利于进一步变形，这反过来又进一步加强了织物，并保持晶体较小。(4)这就是为什么在相同的应力和温度下，冰期冰在简单剪切下的应变率大约是全新世冰的2.5倍。(5)在其他应力系统下的冰河时期的冰，例如大约在冰厚度的上60%的冰，在基岩空洞中，在固定的冰分水岭中，在冰流和冰架中，不会有增强的流动。(6)一个各向异性的流动关系必须用于详细模拟极地冰盖。
Data on the mechanical properties, texture, fabric, and impurity content of ice deposited during the last glaciation are reviewed. The conclusions are: (1) Chloride and possibly sulphate ions, in concentrations high relative to those in Holocene ice, impede grain-boundary migration and grain growth so that the crystals remain small. (2) Such ice, in shear parallel to the ice-sheet bed, develops a strong, near-vertical, single-maximum fabric. (3) This fabric favours further deformation and this, in turn, further strengthens the fabric and keeps the crystals small. (4) This is why the strain rate in ice-age ice, in simple shear, is some 2.5 times that in Holocene ice at the same stress and temperature. (5) Ice-age ice under other stress systems, such as ice in roughly the upper 60% of the ice thickness, in bedrock hollows, at a stationary ice divide, in ice streams and in ice shelves, will not have enhanced flow. (6) An anisotropic flow relation must be used for detailed modelling of polar ice sheets.