Abstract The low-water Moorhead Phase of glacial Lake Agassiz has been attributed to rapid drawdown in lake level contemporaneous with the onset of the Younger Dryas cold reversal. We examine the radiocarbon and optically stimulated luminescence dates associated with the Moorhead and subsequent high-water Emerson Phases in the Lake Agassiz basin. We apply manual and statistical filters to vet the chronological dataset (n = 116), resulting in the exclusion of about one fourth of existing dates. A Bayesian model applied to the filtered dataset (n = 87) yields a modelled 2σ age range for the onset of the Moorhead Phase of 12,410–12,060 cal yr BP, post-dating the onset of the Younger Dryas. The modelled 2σ ages for onset and termination of the Emerson Phase are 11,570–11,290 and 10,690–10,340 cal yr BP, respectively. The dataset and model do not necessarily preclude freshwater flux from Lake Agassiz drawdown during the Moorhead Phase as the trigger for the Younger Dryas cold reversal, but they do indicate that this freshwater drainage interpretation relies on only a few low-precision radiocarbon dates that are identified statistically as outliers. The lingering uncertainty in the radiocarbon chronology for Lake Agassiz, despite rigorous filtering and application of a Bayesian calibration model, strongly suggests that additional high-quality radiocarbon dates from clear depositional settings in the Lake Agassiz basin are required to further constrain lake level histories and linkages to abrupt deglacial climate change.

中文翻译：

---

评估冰川阿加西湖的 Moorhead 和 Emerson 阶段的年龄及其与新仙女木冷逆转的时间联系

摘要 冰川湖 Agassiz 的低水 Moorhead 阶段归因于与年轻的仙女木冷逆转同时发生的湖水位快速下降。我们检查了与阿加西湖盆地中的 Moorhead 和随后的高水位 Emerson 阶段相关的放射性碳和光激发发光日期。我们应用手动和统计过滤器来审查按时间顺序排列的数据集（n = 116），从而排除了大约四分之一的现有日期。应用于过滤数据集 (n = 87) 的贝叶斯模型为 12,410–12,060 cal yr BP 的 Moorhead 阶段开始产生了一个建模的 2σ 年龄范围，在新仙女木开始后约会。模拟的艾默生相开始和终止的 2σ 年龄分别为 11,570–11,290 和 10,690–10,340 cal yr BP。数据集和模型不一定排除 Moorhead 阶段阿加西湖水位下降的淡水通量作为新仙女木冷逆转的触发因素，但它们确实表明这种淡水排水解释仅依赖于已确定的几个低精度放射性碳日期统计为异常值。尽管严格过滤并应用了贝叶斯校准模型，但阿加西湖放射性碳年代学中挥之不去的不确定性强烈表明，需要从阿加西湖盆地清晰的沉积环境中获得额外的高质量放射性碳日期，以进一步限制湖水位历史和联系到突然的冰消期气候变化。但他们确实表明，这种淡水排水解释仅依赖于在统计上被确定为异常值的少数低精度放射性碳日期。尽管严格过滤并应用了贝叶斯校准模型，但阿加西湖放射性碳年代学中挥之不去的不确定性强烈表明，需要从阿加西湖盆地清晰的沉积环境中获得额外的高质量放射性碳日期，以进一步限制湖水位历史和联系到突然的冰消期气候变化。但他们确实表明，这种淡水排水解释仅依赖于在统计上被确定为异常值的少数低精度放射性碳日期。尽管严格过滤并应用了贝叶斯校准模型，但阿加西湖放射性碳年代学中挥之不去的不确定性强烈表明，需要从阿加西湖盆地清晰的沉积环境中获得额外的高质量放射性碳日期，以进一步限制湖水位历史和联系到突然的冰消期气候变化。