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Flow of Antarctic ice under high hydrostatic pressures

高静水压下的南极冰流

基本信息

批准号：
61460045
负责人：
MAE Shinji
金额：
$ 3.71万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1986
资助国家：
日本
起止时间：
1986 至 1988
项目状态：
已结题

项目摘要

Main results obtained in this project are summarized as follows.1. Plastic deformation of Antarctic ice at temperatures near melting point and under high hydrostatic presures (1). The dependence of strain rate on stress was not effected by temperature and hydrostatic pressure. (2). Hydrostatic pressure caused the softening of ice crystals. (3). The strain rate at temperatures near melting point increased compared with that extraporated from low temperature region.2. Behavior of lattice defects which influence the deformation of ice (1). The process of deformation of ice cryatals was determined by selfinterstitials which were interstitial water molecules and influenced climb motion of dislocations in ice. (2). X-ray analysis of deformed ice crystals under high hydrostatic pressures indicated that the pressure dependence of diffusion coefficient of ice was the same as that of the deformation rate.3. Air-hydrate single crystals in ice Air-hydrate crystals of which the size was about 10 - 100 m existed in ice sheet deeper than 1000m. The crystal is considered to affect the flow of ice sheets. (1). Air-hydrate crystal could be nucleated artificially in a tank made for a special high hydrostatic pressure experiments. The number of nucleated crystals depended on total air content in ice and the nucleation rate depended on temperature. (2). X-ray analysis of Air-hydrate crystals revealed that the structure of air-hydrate crystals was belong to " structure II " of hydrate crystals and determined the position of O_2 and N_2 molecules in cages of hydrate.

本课题取得的主要成果概括如下：1.南极冰在熔点附近和高静水压力下的塑性变形(1)。应变率对应力的依赖性不受温度和静水压力的影响。(2)。静水压力导致冰晶软化。(3)。熔点附近的应变速率高于低温区的应变速率。影响冰变形的晶格缺陷行为(1)。冰晶的变形过程是由自身间隙水分子决定的，并影响位错在冰中的爬升运动。(2)。对高静水压下变形冰晶的X射线分析表明，冰的扩散系数与变形速率对压力的依赖关系相同。冰层中存在空气水合物单晶，其大小约为10-100m，存在于1000m以下的冰盖中。这种晶体被认为会影响冰盖的流动。(1)。空气水合物晶体可以在专门用于高压实验的储罐中人工成核。成核结晶的数量取决于冰中的总空气含量，成核速率取决于温度。(2)。对空气水合物晶体的X射线分析表明，空气水合物晶体的结构属于水合物晶体的“结构II”，并确定了O_2和N_2分子在水合物笼子中的位置。