LAC DU BONNET STRUCTURE
by: Charles O’Dale
- Type: Simple
- Location: N 54° 24′ W 95° 48′
- Diameter: ~3.8 Km;
- Age (ma):~75a – CRETACEOUS
a the age is based on the thin sedimentary cover near the shield boundary.
Evidence in support of a meteorite impact crater at Poplar Bay, Lac du Bonnet, southeastern Manitoba
Poplar Bay, in southeastern Manitoba, is a circular lake approximately 3 km in diameter, 21 m in depth, and is framed by radial and arcuate photolineaments. Geophysical study of Poplar Bay shows a unique magnetic signature, and results of a gravity survey indicate a profound deficiency of mass under the lake. The form of the gravity anomaly is circular, and it has a maximum value of −7 mGal.There is no evidence of an igneous origin for the feature and data indicate the plausibility of a meteorite impact origin for Poplar Bay. (Trueman 1976)
Poplar Bay, Manitoba. 50°23’N, 95°47’W. This 3 km diameter crater is located in the Interior Platform of the Great Plains. However, it is near the Shield boundary and sedimentary cover is thin. It is aged 75 m.y. The crater has formed a large bay within Lac du Bonnet, somewhat similar to Deep Bay in Reindeer Lake. Aeromagnetic maps have been secured and examined. They indicate signatures favourable to meteoritic impact formation with circular contours, low gradients and a total relief of 100 nT. Map numbers are 4070G and 7124G Pointe du Bois (Clark).
Clark, J .F. MAGNETIC SURVEY DATA AT METEORITIC IMPACT SITES IN NORTH AMERICA Geomagnetic Service of Canada
Brent Dalrymple, Radiometric Dating Does Work! Reports of the National Center for Science Education
Trueman, D. L. ; Evidence in support of a meteorite impact crater at Poplar Bay, Lac du Bonnet, southeastern Manitoba, Canada; Canadian Journal of Earth Sciences, v. 13n. 11, p. 1608-1612; 1976