Manicouagan Reservoir (also Lake Manicouagan) is an annular lake in central Quebec, Canada, covering an area of 1,942km2 (750sqmi). The lake island in its centre is known as René-Levasseur Island, and its highest point is Mount Babel. The structure was created 214 (±1) million years ago, in the Late Triassic, by the impact of a meteorite 5km (3mi) in diameter. The lake and island are clearly seen from space and are sometimes called the "eye of Quebec". The lake has a volume of 137.9km3 (33.1cumi).[1][2]
The crater is a multiple-ring structure about 100km (60mi) across, with the reservoir at its 70km (40mi) diameter inner ring being its most prominent feature. It surrounds an inner island plateau called René-Levasseur Island and Mount Babel is the highest peak of the island, at 952m (3,123ft) above sea level and 590m (1,936ft) above the reservoir level. The Louis-Babel Ecological Reserve makes up the central part of the island.
Impact crater
Manicouagan Reservoir impact crater
Impact crater/structure
Confidence
Confirmed
Diameter
100km (62mi) (originally)
72km (45mi) (visible today)
Impactor diameter
5km (3.1mi)
Age
214 ± 1 Ma
Manicouagan Reservoir lies within the remnant of an ancient eroded impact crater (astrobleme). The crater was formed following the impact of an asteroid with a diameter of 5km (3mi), which excavated a crater originally about 100km (62mi) wide, although erosion and deposition of sediments have since reduced the visible diameter to about 72km (45mi). It is the Earth's sixth-largest confirmed impact crater according to rim-to-rim diameter.[4] Mount Babel is interpreted as the central peak of the crater, formed by post-impact uplift.
It is one of the oldest known impact craters. 1992 radiometric dating has estimated that impact melt within the crater has an age of 214 ± 1 million years. A later estimate found an age of 215.4 ± 0.16 Ma.[5] As this is more than 12 million years before the end of the Triassic, the impact that produced the crater cannot have been the cause of the Triassic–Jurassic extinction event.[6][7]
Multiple impact event claims
It was suggested that the Manicouagan crater may have been part of a multiple impact event which also formed the Rochechouart impact structure in France, the Saint Martin crater in Manitoba, the Obolon' crater in Ukraine, and the Red Wing crater in North Dakota. David Rowley, a geophysicist, with the University of Chicago, working with John Spray of the University of New Brunswick and Simon Kelley of the Open University, discovered that the five craters appeared to form a chain, indicating the breakup and subsequent impact of an asteroid or comet,[8] similar to the well observed string of impacts of Comet Shoemaker–Levy 9 on Jupiter in 1994.[9] However, more recent work has found that the craters formed many millions of years apart, with the Saint Martin crater dating to 227.8 ± 1.1 Ma.[10] While the Rochechouart structure formed 206.92 ± 0.20/0.32 Ma.[11]
Daniel-Johnson Dam, the primary dam on the Manicouagan Reservoir, supports the Manic-5 hydro-power station
The Manicouagan Reservoir as it presently exists was created in the 1960s, by flooding the earlier Lake Mushalagan (Mouchalagan) to the west of the central plateau and then-smaller Manicouagan to the east, by construction of the Daniel-Johnson dam.[12] The works were part of the enormous Manicouagan or Manic series of hydroelectric projects undertaken by Hydro-Québec, the provincial electrical utility. The complex of dams is also called the Manic-Outardes Project because the rivers involved are the Manicouagan and the Outardes.
The reservoir acts as a giant headpond for the Manicouagan River, feeding the Jean-Lesage generating station (Manic-2), René-Lévesque generating station (Manic-3), and Daniel-Johnson Dam (Manic-5) generating stations downstream. In the peak period of the winter cold, the lake surface is usually lower, since the turbines run all the time at peak load to meet the huge electrical heating needs of the province. The surface of the lake also experiences low levels in the extreme periods of heat in New England during the summer, since in that period Hydro-Québec sells electrical energy to the joint New England grid and individual utilities in the United States.
Ramezani, J., S. A. Bowring, M. S. Pringle, F. D. Winslow, III, and E. T. Rasbury (2005). "The Manicouagan impact melt rock: a proposed standard for intercalibration of U-Pb and 40Ar/39Ar isotopic systems". 15th V.M. Goldsmidt Conference Abstract Volume, p. A321.
Spray, John G.; Kelley, Simon P.; Rowley, David B. (1998). "Evidence for a late Triassic multiple impact event on Earth". Nature. 392 (6672): 171–173. doi:10.1038/32397.
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