INVESTIGATION OF PALEOCLIMATE AND FLOW HISTORY OF ICE SHEET BY ICE CRYSTAL EVOLUTION MODEL IN ICE SHEET

本项目的目标是：1）研究冰中化学杂质的行为及其与晶界迁移的相互作用，以及杂质对冰力学性质的影响; 2）利用我们开发的晶体结构演化模型，发展从冰芯晶体结构和组构数据中提取古气候和冰盖流动历史信息的方法。通过对人工冰的晶粒生长/再结晶实验和力学性能测试，取得了以下研究成果：1.建立了制备细晶冰的工艺（[约等于] 100 um）2.得到了冰的晶界迁移率随温度和杂质浓度的变化规律当杂质浓度大于ppms和温度高于-5 ℃时，含杂质的冰比纯冰更软。4.我们发现了冰晶中小角度晶界形成时的晶体形变和c轴旋转行为，并将这些发现应用于我们的晶体织构演化模型中。

The objectives of this project are 1) investigation of the behavior of chemical impurities in ice and its interaction with grain boundary migration and the effect of impurities on mechanical properties of ice, and 2) development of the method that can derive the information about paleoclimate and ice sheet flow history from ice core crystal texture and fabric data by using the crystal texture evolution model developed by us. We conducted the grain growth/recrystallization experiments and the mechanical tests with artificial grown ice and obtained following results.1.We established the techniques that produce the ice samples with fine crystal (【approximately equal】100um) and homogeneous distribution of low concentration chemical impurities.2.We obtained the temperature dependence and impurity concentration dependence of grain boundary migration rate of ice.3.In the regime of high impurity concentration more than ppms and high temperature (>-5 degree C) the ice contained impurity become softer than pure ice.4.We found the behaviors of crystal deformation and c-axis rotation when the small angle boundary formation in ice crystals.We will develop our crystal texture evolution model taking account the findings above.