Major collapse event of the East Antarctic Ice Sheet in Pliocene
Liu Xiaohan1, Wei Lijie2, Huang Feixin3, Fang Aimin3, Ju Yitai3, Li Xiaoli4, Zhou Xuejun1
1. Key Laboratory of Continental Collision and Uplift, Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085;
2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029;
3. China Metallurgical Geology Bureau, Beijing 100025;
4. Beijing Natural Museum, Beijing 100050
The multi-disciplinary study of past ice surface elevations in the Grove Mountains of interior East Antarctica provide direct land based data on the behaviour of the East Antarctic Ice Sheet since the Pliocene.The glacial geology,the ages of cold desert soils,the depositional environment of younger moraine sedimentary boulders and their spore pollen assemblages combine to imply a possible significant shrinkage of the ice sheet before the Middle Pliocene Epoch,with the ice sheet margin retreating south of the Grove Mountains(～400 km south from its present coastal position).Exposure age measurements of bedrock indicate that the elevation of the ice surface in the Grove Mountains region subsequently rose at about Mid-Pliocene to at least 400 m higher than today's levels.The ice surface then progressively lowered,with some minor fluctuations.Middle to Late Pleistocene exposure ages found on the lowest samples,at the ice/bedrock contact line,indicate a long period with ice surface elevations was kept at current level or complex fluctuation history during the Quaternary Epoch.Such event of Antarctic ice sheet collapse should correspond with some of huge tectonic events in north hemisphere in global scale,such as the Messinian salinity crisis in the Mediterranean region.