Paleohydraulics of the last outburst flood from glacial Lake Agassiz and the 8200 BP cold event
- 作者：Clarke ; Garry K.C. ; Leverington ; David W. ; Teller ; James T. ; Dyke ; Arthur S.
- 刊名：Quaternary Science Reviews
- 出版年：2004
- 期刊代码：78_02773791
- 类别：ear
- 出版时间：February, 2004
- 卷：23
- 期：3-4
- 页码：389-407
- 文件大小：1.00 M
摘要
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<sup>14sup>Ckyr and drained into Hudson Bay about 7.7<sup>14sup>Ckyr(8.45calkyr). 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 Kinojévis level of Lake Agassiz. For this maximum filling, the impounded water volume available to produce floods is estimated as 40,000–151,000km<sup>3sup>, 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 8.2calkyrBP. 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 ![]()
border=0 SRC=/images/glyphs/BQ1.GIF>5Sv and ![]()
border=0 SRC=/images/glyphs/BQ1.GIF>0.5yr. 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.