Dating of Quaternary Sediments and Ice Sheets History in East Antarctica

我们研究了南极东部Lutzow-Holm海湾地区包括原地化石贝壳在内的凸起海滩沉积与冰川沉积之间的地层关系，以澄清南极冰盖不同于北半球冰盖，在海洋同位素阶段2期间不是最大的，而在46ka以上的年龄是最大的。然而，46ka接近14C分析的极限，对污染的影响很敏感。因此，通过其他测年方法获得的年龄将对解释这些数据有很大帮助。为此，我们对东南极Lutzow-Holm湾地区第四纪沉积物的光激发发光(OSL)、电子自旋共振(ESR)和宇宙成因年龄进行了研究，并与AMS 14C年龄进行了比较，并讨论了晚更新世的年代学。尽管我们样品中的一些OSL或宇宙成因年龄与14C年龄有很大的不同，但如果考虑到储层校正等校准因素，OSL、14C和宇宙成因年龄似乎是一致的。虽然我们应该做更复杂的测年实验，但我们可以再次确认，在末次盛冰期期间，东南极冰盖并没有重新推进到大豆海岸最北端的无冰区。冰盖有可能在大约50,000或80,000年前从该地区撤退。

We have been studied the stratigraphic relationship between raised beach deposits including in-situ fossil shells and glacial deposits in the Lutzow-Holm Bay region, East Antarctica, to clarify that the Antarctic ice sheet, unlike the northern hemisphere ice sheet, was not the greatest during the marine isotope stage (MIS) 2 but the greatest at the age older than 46 ka. The 46 ka is, however, close to the limit of 14C analysis and sensitive to the effect of contamination. Therefore, ages obtained by other dating methods would be of great help in interpreting those data. For this reason we investigate on optically stimulated luminescence (OSL), electron spin reasonance (ESR) and cosmogenic dates of Quaternary sediments in the Lutzow-Holm Bay region, East Antarctica, to compare them with AMS 14C dates and to discuss on late Pleistocene chronology.Though some OSL or cosmogenic ages from our samples dearly differ from 14C ages, most of OSL, 14C, and cosmogenic dates seem to be consistent if we take calibration factors such as reservoir correction into account. While we should make further sophisticated dating experiments, we can reconfirm that the East Antarctic Ice Sheet did not re-advance to the ice-free area on the northernmost part of the Soya Coast during the LGM. There is a possibility that the ice sheet retreated from the area during the period prior to about 50,000 or 80,000 yrBP.