IMPACT CRATER EXPLORATIONS
by: Charles O'Dale
LAC COUTURE IMPACT CRATER
At the time of this impact in the Silurian period, life was beginning to emerge from the oceans and colonize the land.
|complex meteorite crater. Rock breccia found on some islands on the west shore is believed to have been dredged from the lake by glacial action. Analysis of this breccia has shown the micro-fracturing of individual crystals typical of impact craters (Grieve 2006).|
La Moinerie Crater, Lac Couture has experienced substantial glacial erosion since impact and all that remains is a circular water filled hole in the bedrock that contains the meteorite crater. We circled the crater in a counter-clockwise direction from the north-east around the western rim of the crater and exiting to the south-east. These images are of the crater from the north, north-west and south respectively and give you an appreciation for the immensity of the impact that happened here. The micro-fractured breccia that confirmed this feature as an impact site was recovered from the islands pictured in the image from the north-west.|
This south-east view (right) illustrates the terrain type in the foreground that was penetrated by the meteorite leaving this deep circular lake. We departed toward Kuujjuaq for fuel (the nearest place where it was available) to continue our explorations.
Side NotePingualuit Crater and were so impressed with the beauty of the area that I wanted to share it with you.
The village of Salluit (right) is neatly tucked into this valley. The airport is on top of the 1000’ hill to the right (south) of the village. You can barely make out the road we walked down to visit the village later that evening. We had a good workout walking back up that hill!
Beals, C. S., Dence, M.R. and Cohen,A.J., Evidence for the impact origin of Lac Couture. Ottawa Dominion Observatory Publications, v. 31, pp. 409-426. 1967.
Bottomley, R. J., York, D. and Grieve,R.A.F., 40Argon-39Argon dating of impact craters. Proceedings Lunar and Planetary Science Conference 20th, pp. 421-431. 1990.
Grieve, R.A.F., Impact Structures in Canada. Geological Association of Canada, 2006.
Robertson, P. B., Petrography of the bedrock and breccia erratics in the region of Lac Couture, Quebec. Master's Thesis, Pennsylvania State University, University Park. 1965.