极地研究

极地研究 ›› 1990, Vol. 1 ›› Issue (1-English): 1-9.

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EVOLUTION OF THE ANTARCTIC ICE SHEET SINCE LATE PLEISTOCENE

Zhang Qingsong   

  1. Institute of Geography, Chinese Academy of Sciences, Beijing 100101
  • 出版日期:1940-03-30 发布日期:1940-03-30
  • 通讯作者: Zhang Qingsong

EVOLUTION OF THE ANTARCTIC ICE SHEET SINCE LATE PLEISTOCENE

Zhang Qingsong   

  1. Institute of Geography, Chinese Academy of Sciences, Beijing 100101
  • Online:1940-03-30 Published:1940-03-30
  • Contact: Zhang Qingsong

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摘要：

Available data show that the of fossil plants testified that the Antarctica was a rather warm or even hot and humid region covered with forest from Devonian to Cretaceous [periods. Furthermore, even Antarctic coasts stilll kept in a warm and humid condition until early Tertiary of 37 Ma ago. It therefore can be considered that the Antarctica was not situated at its present position, but in tropic or temperate zone before the Tertiary. Antarctic ice sheet has begun to appear in the Pligocene of 26Ma ago. It was very much earlier than the glaciations in everywhere of the world. For the reasons a most important event was the separating of Antarctic Peninsula from South America in 35 Ma ago. Drake Passage therefore occurred and Antarctic circulation appeared, and then Antarctic continent became an isolated cold land. Glacial changes have happened on the Antarctic ice sheet from late Tertiary to Quaternary periods. However, it has been confirmed that the Antarctic ice sheet has a great extension during the latest Pleistocene glaciation of 25000-l0000a B. P. About 18000a ago, the Antarctic ice sheet was 450-1000 m thicker and much larger than that at present. By that time the ice sheet grounded on the conticental shelves. Sea level might be 100-150 m or more lower than present sea level. Sca ice covered areas in winter and in summer were 10 and 2 times respectively than that today. It was much warmer in middle Holocene (7500-5000 a B. P.) than today in Antarctic region. By that time, a large amount of ice was melt away, which, on one hand.[caused a rapid rising of sea level, transgression immediately occurred; on the other hand, as continental load decreased due to the melting of ice sheet, the isostatic uplifting consequently followed and the marine terraces formed along Antarctic coasts in middle Holocene, Now the glacio-isostatic uplift is still going on. For a total uplift of 10-25 m since 6000 a B. P. the mean rate of 1.5-4mm/a is estimated in different places of Antarctic coasts. Antarctic ice sheet (including ice shelves) has been retreating recently, Meanwhile, the inland snow accumulation has been increasing in the past decades of years, both of them are corresponding to the rising of annual mean temperature since 1910 A. D.

关键词: Antarctica, Paleography, Evolution of ice sheet

Abstract:

Available data show that the of fossil plants testified that the Antarctica was a rather warm or even hot and humid region covered with forest from Devonian to Cretaceous [periods. Furthermore, even Antarctic coasts stilll kept in a warm and humid condition until early Tertiary of 37 Ma ago. It therefore can be considered that the Antarctica was not situated at its present position, but in tropic or temperate zone before the Tertiary. Antarctic ice sheet has begun to appear in the Pligocene of 26Ma ago. It was very much earlier than the glaciations in everywhere of the world. For the reasons a most important event was the separating of Antarctic Peninsula from South America in 35 Ma ago. Drake Passage therefore occurred and Antarctic circulation appeared, and then Antarctic continent became an isolated cold land. Glacial changes have happened on the Antarctic ice sheet from late Tertiary to Quaternary periods. However, it has been confirmed that the Antarctic ice sheet has a great extension during the latest Pleistocene glaciation of 25000-l0000a B. P. About 18000a ago, the Antarctic ice sheet was 450-1000 m thicker and much larger than that at present. By that time the ice sheet grounded on the conticental shelves. Sea level might be 100-150 m or more lower than present sea level. Sca ice covered areas in winter and in summer were 10 and 2 times respectively than that today. It was much warmer in middle Holocene (7500-5000 a B. P.) than today in Antarctic region. By that time, a large amount of ice was melt away, which, on one hand.[caused a rapid rising of sea level, transgression immediately occurred; on the other hand, as continental load decreased due to the melting of ice sheet, the isostatic uplifting consequently followed and the marine terraces formed along Antarctic coasts in middle Holocene, Now the glacio-isostatic uplift is still going on. For a total uplift of 10-25 m since 6000 a B. P. the mean rate of 1.5-4mm/a is estimated in different places of Antarctic coasts. Antarctic ice sheet (including ice shelves) has been retreating recently, Meanwhile, the inland snow accumulation has been increasing in the past decades of years, both of them are corresponding to the rising of annual mean temperature since 1910 A. D.

Key words: Antarctica, Paleography, Evolution of ice sheet