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

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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.