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Studying the moon  …  in Labrador

By Michelle Osmond

There is a lake in northern Labrador, which has more in common with the moon than any other place on earth. The lake was formed in a crater about 35 million years ago and, according to researchers, it’s an impact crater that is very similar to craters on the moon.

Mistastin Lake (or Kamestastin Lake, as the Innu call it), measures 16 kilometres wide, and sits inside a 28 kilometre wide crater about 120 kilometres inland from Nain close to the Quebec border. Most lakes were produced by glaciers about 10,000 years ago but the fact that this is an impact lake makes it one of the oldest lakes in Labrador. And for most of September, Dr. Paul Sylvester of the Department of Earth Sciences and his team are in Labrador studying it.

“Mistastin Lake is a medium sized impact crater and just to put that into perspective, large scale impacts have been known to wipe out some species on earth,” explained Dr. Sylvester. “It was formed by a meteorite impact into rocks called anorthosites which are rare on Earth but common on the moon.”

In fact, scientists believe that a huge number of meteorites intensely cratered both the moon and Earth some 4 billion years ago and possibly killed off early life forms here. The moon’s surface preserves a record of this intense bombardment but little evidence of this is preserved on Earth because its surface has been continuously worn down by wind and water, and other processes.

Researchers, such as Dr. Sylvester, believe a lot can be learned about the origin and diversity of anorthosite impact melts from studies of melt rocks at Mistastin Lake.

“Rocks that formed by total melting of anorthosites may be more similar to impact melt rocks on the moon than any others on Earth, and provide the best opportunity to understand how meteorite impacts produced such lunar formations,” explained Dr. Sylvester.

Mistastin Lake is known as the last lake in Labrador to freeze and thaw but no one knows exactly how deep it is. So, Dr. Sylvester and his project team, which includes master’s student Cassandra Marion, and field assistant Marc Beauchamp will be diving to the bottom, measuring the depth, and trying to understand more about the geology of lunar craters by studying the impact rocks at the bottom.

They’ll also look at the rim of the crater to study how the melt rock was distributed when it was thrown out of the crater during impact, as well as the structures and how they formed. Another goal for this trip is to get a very large sample (20 gallon drum) of melt rock from the thickest exposure. Among other things, they are looking for zircons which record the solidification of the melt so they can date the impact more precisely (there is an eight million year uncertainty in the best existing date).

Dr. Sylvester’s project is partly funded by the Canadian Space Agency which sees the site as a lunar analog. Other researchers are interested in the area’s cold temperatures, archaeological history and fauna and flora. Dr. Sylvester would eventually like to develop a weather station there and a research station to see it used as a training ground for Canadian astronauts and lunar robots.


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