Fluctuation of Antarctic Ice Sheet and historical development of landforms during Quaternary

1.根据AMS^&lt；14&gt；C测年，到晚更新世，东南极冰盖从大豆海岸最北端的无冰岩石中撤退，可能是最后一次陆间冰盖，并发生了海侵。尽管这一时期的绝对高海平面不得而知，但相对海平面至少比现在的海平面高出10米。从化石贝壳的三角洲^&lt；18&gt；O(PDB)值来看，上一次大冰期南极东部冰盖的融化明显活跃。在大冰盖期间，海平面下降，但东南极冰盖并没有重新推进，至少没有向大豆海岸最北端的无冰岩石推进。可能在大冰盖之后，融水过程变得活跃，然后部分侵蚀了以前隆起的海滩，形成了河流沉积。东南极冰盖在全新世中期从大豆海岸现今的无冰岩石中消退，全新世海侵发生在14&C时代，距今3000~7200年。在不考虑均衡回弹的情况下，高海平面至少达到了20m ASL。海侵可能被一些小的倒退打断了。出现了两次相对稳定的海平面时期，分别在目前海平面以上20米和11米左右。从化石贝壳的δ^&lt；18&gt；O(PDB)值来看，全新世海侵期间东南极冰盖的融化活动比上一次海侵期间要少。在阿蒙森湾地区周围，来自Riiser-Larsen地区湖泊沉积岩芯的AMS^&lt；14&gt；C年代数据表明，该地区自10000年前以来相对海平面一直低于23m。

1. Around the Lutzow-Holm Bay region The East Antarctic Ice Sheet had retreated from the ice-free rocks in the northernmost part of Soya Coast by the late Pleistocene, probably the last interstadial, on the basis of the AMS ^<14>C dating, and marine transgression had occurred there. Although the absolute high sea level during that period is unknown, the relative sea level reached at least 10 m above the present sea level. Melting of the East Antarctic Ice Sheet during the last interstadial had been conspicuously active judging from the delta^<18>O (PDB) values of fossil shells.During the LGM, sea level had fallen ; however, the East Antarctic Ice Sheet did not re-advance, at least on to the ice-free rocks on the northernmost part of the Soya Coast.Probably after the LGM, meltwater process became active, then partially eroded the former raised beach and formed fluvial deposits. The East Antarctic Ice Sheet retreated from the present ice-free rocks along the Soya Coast by the middle of the Holocene.Holocene marine transgression occurred from 3,000 yBP to 7,200 yBP in ^<14>C age. High sea level had reached at least 20 m asl without taking isostatic rebound into consideration. The transgression was probably interrupted by minor regressions. Relatively stable sea-level period occurred twice, around 20 m and 11 m above the present sea level. Melting of the East Antarctic Ice Sheet during the Holocene transgression was less active than during the last interstadial, judging from the delta^<18>O (PDB) values of fossil shells.2. Around the Amundsen Bay regionAMS ^<14>C date, from the lake sediment core in the Mt.Riiser-Larsen region, indicates that relative sea-level at the region has been lower than 23 m since 10,000 yBP.