东南极拉斯曼丘陵及邻区基于暴露年龄的末次冰退模式研究

There is no conclusion on the time when the last deglaciation of the East Antarctic ice sheet has occurred in Larsemann Hills and adjacent areas. Studies on the age of bedrock and boulder’s exposure show that the last deglaciation time ranges from 44.7 ka to 8.8 ka in Larsemann Hills and adjacent Bolingen islands according to their distances to the ice edge. It indicates that the last deglaciation is a long process, and it is earlier than the LGM. However it should be noted all the collected samples are relatively closer to the ice edge except one from Bolingen islands. In this study the Bedrock and boulder samples are farer away from the ice sheet’s edge in Larsemann Hills and adjacent areas than the studied samples, and the samples’ dating will show the accurate time when the deglaciation began and finished. We can calculate the rate of deglaciation based on the distance between the ice sheet and samples and can judge the direction of deglaciation by measuring on glacial striation of the bedrock surface in different areas, which make further the study on the last deglaciation evolution in East Antarctic ice sheet.

拉斯曼丘陵及相邻地区东南极冰盖末次冰退开始时间尚未确定。基岩和冰川漂砾暴露年龄研究表明，拉斯曼丘陵和相邻的Bolingen群岛的末次冰退的时间介于44.7 ka到8.8 ka之间，并与采样位置到现代冰盖边缘位置的距离不同有关。因此，末次冰退是一个持续的过程，而末次冰退开始的时间明显早于末次冰盛期。然而，已研究样品中除Bolingen群岛的一个样品外都存在位置距冰盖边缘较近的局限性。本项目在拉斯曼丘陵及相邻地区所采样品，比前人已经研究过的样品距冰盖边缘更远，准确测定这些基岩样品的暴露年龄，能更准确确定在拉斯曼及相邻地区冰盖退缩开始及最终完成的时间；根据对不同地区裸露岩石表面冰川擦痕的统计测量，确定冰川退却时的运动方向；并结合样品位置距离冰盖的远近，可计算冰退速率；这将完善该地区的东南极冰盖末次冰退演化的过程。