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The ocean-driven instability of the South Pacific sector of the West Antarctic Ice Sheet since 773 ka
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  • Jiakai Wang,
  • Zheng Tang,
  • Fengming Chang,
  • Qingyun Nan,
  • Zhifang Xiong,
  • Tiegang Li
Jiakai Wang
Institute of Oceanology of the Chinese Academy of Sciences
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Zheng Tang
First Institute of Oceanography
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Fengming Chang
Institute of Oceanology, Chinese Academy of Sciences
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Qingyun Nan
Institute of Oceanology, Chinese Academy of Sciences
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Zhifang Xiong
First Institute of Oceanography, State Oceanic Administration, China
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Tiegang Li
First Institute of Oceanography

Corresponding Author:tgli@fio.org.cn

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Abstract

Insight into the causes of the West Antarctic Ice Sheet (WAIS) stability over middle Pleistocene glacial/interglacial (G/IG) cycles is fundamental to our understanding of the response of the climate system to the cryosphere. Here, to clarify the mechanism of WAIS stability during the late Quaternary period, we provide iceberg-rafted debris (IRD) contents, clay mineral, and Sr-Nd isotopic analyses of the piston core ANT34/A2-10. The core was recovered from the seasonal sea ice region in the Antarctic Zone of the Amundsen Sea with a ~773 ka BP chronology. The endmember analysis of clay minerals shows marked differences in sediment provenance at site ANT34/A2-10 between IRD peak interval and low IRD content interval in G/IG cycles. And the Sr-Nd isotopic endmember analysis in IRD peak intervals restricts the sediment provenance in the Victoria Land. We suggest that shifts in the sediment provenance resulted from the variations in iceberg trajectories, which connected to the significant shifts in the atmospheric system at the IRD peak intervals.
Moreover, a contemporaneous strengthened ocean-driven positive feedback occurred between the increased wind-driven upwelling of warm, well-ventilated Circumpolar Deep Water and the intense ice mass loss process (including iceberg calving and basal melting process) with the instability of the WAIS. Furthermore, our results reveal that the variation of WAIS stability is sensitive to the local summer insolation forcing. These pieces of evidence recorded in the pelagic South Pacific Southern Ocean may strongly reflect the significant variations in ocean-driven and orbital forcing on WAIS stability on the orbital scale.