Paleohydraulics of the last outburst flood from glacial Lake Agassiz and the 8200 BP cold event
Paleohydraulics of the last outburst flood from glacial Lake Agassiz and the 8200 BP cold event
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DOI：
10.1016/j.quascirev.2003.06.004
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发表时间：
2004-02-01
影响因子：
4
通讯作者：
Dyke, AS
中科院分区：
文献类型：
--
作者：
Clarke, GKC;Leverington, DW;Dyke, AS
在北美最后一次冰消期，巨大的冰前湖沿着劳伦泰德冰盖的南部边缘形成。其中最大的是冰川湖阿加西斯，形成约11.7 C-14 kyr和排水到哈德逊湾约7.7 C-14 kyr（8.45 cal kyr）。这些湖泊的溢流被引导到密西西比、圣劳伦斯和麦肯齐排水系统，人们认为，路由的切换伴随着海洋环流的响应，产生了突发的气候事件。当横跨哈德逊湾的冰坝最终决堤时，一场巨大的洪水排干了阿加西湖，阿加西湖穿过哈德逊海峡进入拉布拉多海。就蓄水量而言，最大的水库与阿加西斯湖的Kinojevis水位有关。根据冰缘的位置和使用的路线，对于最大填充量，可用于产生洪水的蓄水量估计为40，000 - 151，000 km（3）。储存的淡水迅速释放的时间正好在全新世早期8.2 cal kyr BP的冷却事件之前。我们用Spring-Hutter理论模拟了源自冰下排水管道的洪水过程线，发现洪水量级和持续时间与5Sv和0.5yr相似。多个填充和洪水是可能的，因为是一个复杂的多脉冲结构的单一洪水。模拟结果表明，阿加西湖爆发的洪水可能在湖面高程降至海平面之前就已终止，并且当建立了连接阿加西湖和泰瑞尔海的稳定排水通道时，洪水就结束了。(C)2003爱思唯尔有限公司。保留所有权利。
During the last deglaciation of North America, huge proglacial lakes formed along the southern margin of the Laurentide Ice Sheet. The largest of these was glacial Lake Agassiz, which formed about 11.7 C-14 kyr and drained into Hudson Bay about 7.7 C-14 kyr (8.45 cal kyr). Overflow from these lakes was variably directed to the Mississippi, St. Lawrence and Mackenzie drainage systems and it is thought that switches in routing were accompanied by a response in ocean circulation that produced abrupt climate events. When the ice dam across Hudson Bay finally was breached, a massive flood drained Lake Agassiz, which was routed through Hudson Strait to the Labrador Sea. In terms of stored water volume the largest reservoir was associated with the Kinojevis level of Lake Agassiz. For this maximum filling, the impounded water volume available to produce floods is estimated as 40,000-151,000 km(3), depending on the location of the ice margin and route used. The timing of this rapid release of stored freshwater just precedes the early Holocene cooling event at 8.2 cal kyr BP. We use the Spring-Hutter theory to simulate flood hydrographs for floods that originate in subglacial drainage conduits and find that flood magnitude and duration are similar to5 Sv and similar to0.5 yr. Multiple fillings and floods are possible as are single floods having a complex multipulse structure. Modelling results suggest that the outburst flood from Lake Agassiz may have terminated before the lake surface elevation dropped to sea level and that the flood ended when a stable drainage channel was established, connecting Lake Agassiz to the Tyrrell Sea. (C) 2003 Elsevier Ltd. All rights reserved.