Abstract Geological reconstruction of the retreat history of the East Antarctic Ice Sheet (EAIS) since the Last Glacial Maximum (LGM) is essential for understanding the response of the ice sheet to global climatic change and the mechanisms of retreat, including a possible abrupt melting event. Such information is key for constraining climatic and ice-sheet models that are used to predict future Antarctic Ice Sheet AIS melting. However, data required to make a detailed reconstruction of the history of the EAIS involving changes in its thickness and lateral extent since the LGM remain sparse. Here, we present a new detailed ice-sheet history for the southern Soya Coast, Lutzow-Holm Bay, East Antarctica, based on geomorphological observations and surface exposure ages. Our results demonstrate that the ice sheet completely covered the highest peak of Skarvsnes (400 m a.s.l.) prior to ∼9 ka and retreated eastward by at least 10 km during the Early to Mid-Holocene (ca. 9 to 5 ka). The timing of the abrupt ice-sheet thinning and retreat is consistent with the intrusion of modified Circumpolar Deep Water (mCDW) into deep submarine valleys in Lutzow-Holm Bay, as inferred from fossil foraminifera records of marine sediment cores. Thus, we propose that the mechanism of the abrupt thinning and retreat of the EAIS along the southern Soya Coast was marine ice-sheet instability caused by mCDW intrusion into deep submarine valleys. Such abrupt ice-sheet thinning and retreat with similar magnitude and timing have also been reported from Enderby Land, East Antarctica. Our findings suggest that abrupt thinning and retreat as a consequence of marine ice-sheet instability and intrusion of mCDW during the Early to Mid-Holocene may have led to rapid ice-surface lowering of hundreds of meters in East Antarctica.

中文翻译：

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冰川地貌和地表暴露测年揭示了南极洲东部吕措-霍尔姆湾南部大豆海岸的全新世冰盖突然变薄

摘要 自末次盛冰期（LGM）以来南极东部冰盖（EAIS）退缩历史的地质重建对于理解冰盖对全球气候变化的响应和退缩机制至关重要，包括可能的突然融化事件. 这些信息对于限制用于预测未来南极冰盖 AIS 融化的气候和冰盖模型至关重要。然而，详细重建 EAIS 历史所需的数据涉及其厚度和横向范围的变化，因为 LGM 仍然很少。在这里，我们根据地貌观测和地表暴露年龄，展示了南极洲东部卢佐霍姆湾南部大豆海岸的新的详细冰盖历史。我们的结果表明，冰盖在 ∼9 ka 之前完全覆盖了最高峰 Skarvsnes (400 m asl)，并在早至中全新世（约 9 至 5 ka）期间向东退缩了至少 10 公里。根据海洋沉积物核的有孔虫化石记录推断，冰盖突然变薄和退缩的时间与改良的环极深水 (mCDW) 侵入 Lutzow-Holm 湾的海底深谷相一致。因此，我们提出沿大豆海岸南部 EAIS 突然变薄和后退的机制是由 mCDW 侵入深海底谷引起的海洋冰盖不稳定。南极洲东部恩德比地也报告了这种以相似幅度和时间发生的冰盖突然变薄和退缩。