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东南极冰盖DomeA的内部等时层结构

, PP. 1504-1509

Keywords: 东南极冰盖,DomeA,雷达,内部等时层,深冰芯

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Abstract:

?DomeA被认为是有可能找到超过100万年深冰芯记录的理想钻探地点.冰盖内部的雷达等时层在深冰芯钻探选址和解释反演深冰芯包含的气候信息方面扮演重要角色.通过对中国第21次南极科学考察(CHINARE21,2004/05)期间获得的贯穿DomeA中心区域200km冰盖雷达断面数据的处理,得到DomeA附近的等时层分布.分析表明,在冰盖浅层(0~500m)等时层总体平坦,层间距小于50m,局部出现向斜层(syncline)和背斜层(anticline).在冰盖中、深部(500~2000m),层间距增大为50~100m,呈现为“亮层”.当冰下地形波长与冰厚(3km左右)相当时,内部等时线追踪并趋向平行于冰下地形,局部有褶皱现象;而当冰下地形波长(20km左右)大于冰厚时,等时层不随冰下地形的起伏而起伏;在冰下地形剧烈变化的单个或两个山峰附近,内部等时层被冰下地形强烈扰动.在冰盖底部等时线存在缺失断裂等不连续现象.另外,结合冰盖厚度数据,找出了3个供选择构建预测冰芯钻探年代-深度关系的地点.

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