基于微粒变化对崇测冰帽浅层冰芯的定年结果  

Dating of a Shallow Ice Core from Chongce Ice Cap Using Micro-particle Content

作　　者：韩建康[1] 中尾正义 东久美子 张万昌[4] 和田 朱丰年[1] 

机构地区：[1]湖南师范大学资源与环境研究所,湖南长沙410081 [2]日本综合地球环境学研究所 [3]日本极地研究所 [4]南京大学地球系统科学研究所,江苏南京210093 [5]日本新泻大学积雪区灾害研究所

出　　处：《冰川冻土》2005年第6期846-852,共7页Journal of Glaciology and Geocryology

基　　金：国际合作项目"塔克拉玛干沙漠南缘气候和环境变化的冰芯研究";日本国文部省国际科学研究项目(6204104363043030);日本文部省科技专门协力项目资助

摘　　要：冰芯年代学的建立, 对于稳定同位素定年方法失效的钻点尤为困难. 依据粒径在0.66～1.33μm之间的不可溶尘埃微粒的浓度垂向分布, 并结合阳离子Ca2+的浓度剖面变化, 实现了对崇测冰帽冰芯浅层的断代. 该冰芯钻自海拔6 532 m的冰穹顶部, 解析的18.7 m冰芯长度占到钻点冰层深度约2/5, 辅助的定年参数包括钻点表层5 a的实测净积累率和大气核试验的地层标志. 综合各种技巧定年, 崇测冰帽该冰芯覆盖的记录年代为1902-1992年, 最底部累积误差在±2 a(约为2%).An accurate time scale is necessary for interpretation of an ice core record. The establishment of chronology is especially difficult for sites where the conventional annual--layer counting using stable isotopes fails due to much less snow deposition. In this work, dating from the analysis of insoluble micro-particles ranging from 0. 66 to 1.33μm in diameter, in combination with the soluble Ca^2＋ concentration, was applied to an ice core from a middle-sized Chongce Ice Cap, West Kunlun Mountains of China. The ice core was retrieved from the summit, 6 530 ma. s. 1., of the ice cap. The dated core of 18. 7 m in length represents about 2/5 of the total ice thickness at the drilling site. The assisting dating parameters include the measured net accumulation in the last 5 years prior to the drilling and the stratigraphic marker of atmospheric nuclear weapon test. Based on the combined techniques, a time scale covering the period of 1903--1992 was derived. The cumulative dating uncertainty by the bottom is estimated less than 2 years. This work suggests that the insoluble microparticle takes an advantage in the dating of ice cores from Asian mountainous glaciers. The concentration in a certain size range （〈2 μm）, rather than the total concentration, is more preferable. It is significant to exclude the possible “noise”of weathered mineral dust of local sources.

关 键 词：不可溶微粒 冰芯定年 崇测冰帽 冰芯年代学 同位素定年方法 

分 类 号：P343.6[天文地球—水文科学]