Physical and Structural Properties of the Greenland Ice Sheet Project (GISP II) Deep Core

该奖项是第二个格陵兰冰盖项目(GISPII)的一个组成部分。本次调查将重点研究格陵兰峰会现场GISPII深部钻探的冰芯的地层、松弛特征和晶体结构。研究将包括：1)划定年度分层；2)精确测量密度以监测冰芯老化时的松弛特征；3)确定冰芯松弛的主要机制；4)测量作为冰深度和冰龄函数的晶体尺寸；5)c轴组构测量；6)分析底部冰芯中的碎片。冰的松弛导致其力学条件发生重大变化，在制备和分析岩心样品以进行圈闭气体和化学研究时必须考虑这些变化；c轴组构是解释垂直钻探岩心所代表的冰柱应变历史的主要信息来源。因此，如果我们要准确地评估深部冰芯的深度-年龄关系，并对基于这些冰芯的地球化学和圈闭气体分析的古气候重建有信心，非常仔细地记录这些冰芯的这些关键性质是必不可少的。

This award represents one element of the second Greenland Ice Sheet Project (GISPII). This investigation will focus on the stratigraphy, relaxation characteristics and crystalline structure of ice cores from the GISP II deep drilling at the Summit site, Greenland. Studies will include: 1) delineation of annual layering, 2) precision density measurements to monitor the relaxation characteristics of ice cores as they age, 3) determination of the principal mechanisms by which cores relax, 4) crystal size measurements as a function of the depth and age of the ice, 5) c-axis fabrics measurements, and 6) analysis of debris in basal ice cores. Relaxation of ice results in significant changes in their mechanical condition that must be considered in relation to the preparation and analysis of core samples for entrapped gas and chemical studies; c-axis fabrics constitute the primary source of information for interpreting the strain history of the ice column that vertically drilled cores represent. Accordingly, very careful documentation of these key properties of summit site ice cores is essential if we are to accurately assess the depth - age relationship of deep cores and have confidence in paleoclimate reconstructions based on geochemical and entrapped gas analysis of these cores.