Dating of Quaternary Sediments and Ice Sheets History in East Antarctica

我们研究了东南极洲Lutzow-Holm湾地区隆起的海滩沉积物（包括原位化石壳）与冰川沉积物之间的地层关系，阐明了南极冰盖与北半球冰盖不同，在海洋同位素阶段（MIS） 2不是最大的，而是在大于46 ka的年龄最大。然而，46 ka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，我们研究了东南极洲Lutzow-Holm湾地区第四纪沉积物的光激发发光（OSL）、电子自旋推理（ESR）和宇宙成因日期，并与AMS 14C日期进行了比较，讨论了晚更新世的年代学。虽然我们样品的一些OSL或宇宙成因年龄与14C年龄相差很大，但如果考虑储层校正等校准因素，大多数OSL、14C和宇宙成因年龄似乎是一致的。虽然我们还需要进一步进行更精密的测年实验，但我们可以再次确认南极东部冰盖在LGM期间并没有重新推进到大豆海岸最北端的无冰区。有一种可能性是，冰盖在大约5万或8万yrBP之前从该地区退缩。

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.