科研之友
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摘要
Documenting sub-Antarctic glacier variations during the local last glacial maximum is of major interest to better understand their sensitivity to atmospheric and oceanic temperature changes in conjunction with Antarctic ice sheet changes. However, data are sparse because evidence of earlier glacier extents is for most sub-Antarctic islands located offshore making their observation complex. Here, we present 22 cosmogenic Cl-36 surface exposure ages obtained from five sites at Kerguelen to document the glacial history. The Cl-36 ages from roche moutonnee surfaces, erratics and boulders collected on moraines span from 41.9 +/- 4.4 ka to 14.3 +/- 1.1 ka. Ice began to retreat on the eastern part of the main island before 41.4 +/- 4.4 ka. Slow deglaciation occurred from similar to 41 to similar to 29 ka. There is no evidence of advances between 29 ka and the Antarctic Cold Reversal (ACR) period (similar to 14.5-12.9 ka) period. During the ACR, however, the Bontemps and possibly Belvedere moraines were formed by the advance of a Cook Ice Cap outlet glacier and a local glacier on the Presque Ile Jeanne d'Arc, respectively. This glacier evolution differs partly from that of glaciers in New Zealand and in Patagonia. These asynchronous glacier changes in the sub-Antarctic region are however in agreement with sea surface temperature changes recorded around Antarctica, which suggest differences in the climate evolution of the Indo-Pacific and Atlantic sectors of Antarctica.
- 出版日期2018-3-1
