Freshwater Outburst from Lake Superior as a Trigger for the Cold Event 9300 Years Ago
Freshwater Outburst from Lake Superior as a Trigger for the Cold Event 9300 Years Ago
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DOI：
10.1126/science.1187860
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发表时间：
2010-06
期刊：
影响因子：
56.9
通讯作者：
Shi-Yong Yu;S. Colman;T. Lowell;G. Milne;T. Fisher;A. Breckenridge;Matthew Boyd;J. Teller
中科院分区：
文献类型：
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作者：
Shi-Yong Yu;S. Colman;T. Lowell;G. Milne;T. Fisher;A. Breckenridge;Matthew Boyd;J. Teller
大约 9300 年前，一场普遍的降温事件影响了北半球的大部分地区。这一事件伴随着北大西洋海洋环流的变化，可能是由于劳伦泰德冰盖融化产生的大量淡水注入所致，但融水的来源、规模和流向仍然未知。于等人。 （第 1262 页，4 月 29 日在线发布）提供的证据表明，这次降温事件的触发因素是苏必利尔湖的溃决洪水。重建苏必利尔盆地的湖水位变化表明，9300 年前，湖水位迅速下降了约 45 米，可能是由于漂流坝突然溃决所致。通过北湾-渥太华河-圣路易斯的快速排水根据地质记录，流入北大西洋的圣劳伦斯河谷应该足以扰乱海洋环流。 9300 年前北大西洋戏剧性变冷事件的触发因素是苏必利尔湖的溃决洪水。古气候代理记录揭示了大约 9300 年前北半球范围内普遍存在的变冷事件。北大西洋海洋环流的同期变化意味着淡水强迫。然而，融水的来源、规模和流向仍然未知。苏必利尔湖位于北美洲中部，是调节冰川融水流入海洋的关键地点。在这里，我们展示了该盆地湖面快速下降约 45 米的证据，其中心时间是在距今 9300 年之前，由于该湖东南角的冰川流坝溃坝。我们将约 9300 年前广泛的气候异常归因于通过休伦湖 - 北湾 - 渥太华河 - 圣劳伦斯河输送到北大西洋的淡水爆发。圣劳伦斯河谷。
Down the Drain A pervasive cooling event affected much of the Northern Hemisphere approximately 9300 years ago. This event was accompanied by changes in ocean circulation in the North Atlantic, forced presumably by a large injection of fresh water produced by melting of the Laurentide Ice Sheet, but the source, magnitude, and routing of the meltwater remain unknown. Yu et al. (p. 1262, published online 29 April) present evidence that the trigger for this cooling episode was an outburst flood from Lake Superior. Reconstructing lake-level changes in the Superior basin suggests that a rapid fall of lake level of about 45 meters occurred 9300 years ago, possibly due to the sudden failure of a drift dam. Rapid drainage through the North Bay–Ottawa River–St. Lawrence River valleys into the North Atlantic should have been sufficient to disturb ocean circulation in line with the geologic record. The trigger for the dramatic North Atlantic cooling event 9300 years ago was an outburst flood from Lake Superior. Paleoclimate proxy records reveal a pervasive cooling event with a Northern Hemispheric extent ~9300 years ago. Coeval changes in the oceanic circulation of the North Atlantic imply freshwater forcing. However, the source, magnitude, and routing of meltwater have remained unknown. Located in central North America, Lake Superior is a key site for regulating the outflow of glacial meltwater to the oceans. Here, we show evidence for an ~45-meter rapid lake-level fall in this basin, centered on 9300 calibrated years before the present, due to the failure of a glacial drift dam on the southeast corner of the lake. We ascribe the widespread climate anomaly ~9300 years ago to this freshwater outburst delivered to the North Atlantic Ocean through the Lake Huron–North Bay–Ottawa River–St. Lawrence River valleys.