Abstract The duration and intensity of the early Holocene freshening events has been explained by subglacial outburst(s) from Lake Agassiz, the collapse of a Laurentide Ice Sheet ‘saddle’ overlying Hudson Bay, and/or a combination of the two events. Our field evidence provides new radiocarbon ages and geomorphologic observations to assess the deglacial history of this important region, allowing for revision of the sequence of events. We show that the collapse of the Hudson Bay Ice Saddle in southwestern Hudson Bay occurred between 8.57 ± 0.28 ka BP and 8.11 ± 0.19 ka BP. This event was preceded by at least one subglacial-drainage event through numerous newly-mapped subglacial channels onshore of southwestern Hudson Bay. Lake Agassiz may have experienced multiple subglacial drainage events prior to the final HBIS collapse, accounting for the timing discrepancies in freshwater cooling observed in the North Atlantic. Importantly, this new work links the chronology of events on the southwest (land-based) side of the HBIS to the northeast (marine-based) side of the ice sheet. Additionally, this work provides a potential analog for the behaviour of other ice sheets whose beds lie well below sea level, such as the West Antarctic Ice Sheet, during periods of warming climate.

中文翻译：

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阿加西湖排水支架全新世哈德逊湾冰鞍倒塌

摘要 全新世早期清新事件的持续时间和强度可以通过阿加西湖的冰下爆发、覆盖哈德逊湾的劳伦泰德冰盖“马鞍”的坍塌和/或这两种事件的组合来解释。我们的现场证据提供了新的放射性碳年龄和地貌观测，以评估这一重要地区的冰消历史，从而可以修正事件的顺序。我们表明哈德逊湾西南部的哈德逊湾冰鞍的坍塌发生在 8.57 ± 0.28 ka BP 和 8.11 ± 0.19 ka BP 之间。在此事件之前，至少有一次冰下排水事件通过哈德逊湾西南部海岸上许多新绘制的冰下通道进行。在 HBIS 最终坍塌之前，阿加西湖可能经历了多次冰下排水事件，考虑到在北大西洋观察到的淡水冷却的时间差异。重要的是，这项新工作将 HBIS 西南（陆基）侧的事件年表与冰盖东北（海基）侧的事件联系起来。此外，这项工作为其他冰盖的行为提供了一种潜在的模拟，这些冰盖的床位远低于海平面，例如在气候变暖期间的南极西部冰盖。