Geology of Saskatchewan - Astroblemes

Astroblemes

There are six notable meteorite or comet impact craters in Saskatchewan. Carswell, Deep Bay, and Gow Lake have affected the Canadian Shield area of the north. In the southern Phanerozoic crater are the Viewfield, Elbow, and Maple Creek structures. The Carswell structure is the largest astrobleme at 35 kilometers (22 mi) in diameter. It is estimated that the impact to the Athabasca basin occurred about 478 million years ago during the Ordovician period. The thrust of the impact affected the Athabasca Rock groups. The William River Subgroup and the Douglas and Carswell formations show inversions, thrusting and disruptions. The impact that occurred about 210 million years ago has created the Gow Lake Structure. This lake is 5 kilometers (3.1 mi) in diameter with Calder island centrally located. La Ronge is 160 kilometers (99 mi) south-southwest of the crater location. The other impact crater of the Cambrian shield is the Deep Bay Structure, which created a bay in the southerly part of Reindeer Lake. The crater is about 11 kilometers (6.8 mi) in diameter and about 220 meters (720 ft) at the deepest point. The circular impact ridge 100 meters (330 ft) above water level partially encompasses the crater area. There is some central uplift. The crater was formed about 50 to 150 million years ago. Weyburn is west and Stoughton is north of the Viewfield Impact Structure, a small impact crater 2 kilometers (1.2 mi) in diameter. The impact occurred in the early Jurassic period about 190 million years ago. Oil and gas reserves have been found in the area of the rim breccia Another impact crater in the Phanerezoic crater is the Maple Creek Structure. This impact affected Upper Cretaceous Bearpaw Formation sediments on the north edge of the Cypress Hills, and roughly occurred 75 million years ago. Maple Creek is located north northwest of this 6 kilometers (3.7 mi) diameter crater. The Elbow Impact Structure is 8 kilometers (5.0 mi) in diameter and the impact occurred between 370 to 415 million years ago during the Devonian Period. The crater is located in Maple Bush rural municipality north of Aitkow and west of Grainfield. The Elbow crater is located south of the elbow of the South Saskatchewan, and south of Diefenbaker lake across the waters from the town of Elbow which is north of the South Saskatchewan River.