by: Charles O’Dale
- Type: Simple
- Age Ma: <70 (Geological dating) a
- Diameter: 4 km
- Location: N 49° 55’ W 102° 07’
a several km of Cretaceous sediments fills the cavity
A compilation of source references to magnetic survey data over proven. probable and possible meteorite impact structures in North America shows that more than half of the 58 structures listed have been surveyed magnetically. Several types of magnetic signature. depending on he complexity of the impact structure and also on the geological setting. have been identified. At small simple craters. the magnetic anomalies are generally weakly negative; at complex structures. there may often be intense anomalies associated with the central uplift. Structural interpretation using magnetic data is considered feasible at several sites.
Dumas, Saskatchewan. 49°55’N, 102°07’W. This crater is about 4 km in diameter and less than 70 m.y. old. It is completely buried by several km of Cretaceous sediments filling the cavity. No aeromagnetic data are available at present.
Seismic and borehole data at Dumas, Saskatchewan (T. 11, R.1 & 2, W2M) reveals structural features that suggest hyper–velocity impact during late Cretaceous time.
The anomaly consists of a pronounced, highly disturbed central uplift, a rim syncline, and the suggestion of a positive outer lip. Although some deformation persists into Paleozoic strata, the majority of the relief involves Mesozoic rocks.
Subsurface information appears to rule out any possibility of explaining these features by means of deep–seated tectonic activity and/or solution collapse phenomena.
Brent Dalrymple, Radiometric Dating Does Work! Reports of the National Center for Science Education
J.F. CLARK, MAGNETIC SURVEY DATA AT METEORITIC IMPACT SITES IN NORTH AMERICA Earth Physics Branch Open File Number 83-5 Geomagnetic Service of Canada
H. B. Sawatzky, Two Probable Late Cretaceous Astroblemes In Western Canada—Eagle Butte , Alberta And Dumas, Saskatchewan Society of Exploration Geophysicists
H. B. Sawatzky, Buried impact craters in the Williston Basin and adjacent area, Impact and explosion cratering – Lunar and Planetary Institute 1977