Saint Martin impact structure
Saint Martin is an impact crater in Manitoba, Canada.[1]
It is 40 km (25 mi) in diameter and its age is estimated at 220 ± 32 million years (Triassic). The crater is not exposed at the surface.
Related impact events
Geophysicist David Rowley of the University of Chicago, working with John Spray of the University of New Brunswick and Simon Kelley of the Open University, discovered that the Saint Martin crater was one of five craters in Europe and North America that formed a chain, indicating the breakup and subsequent impact of an asteroid or comet. The other craters are Manicouagan crater in northern Quebec, Rochechouart crater in France, Obolon' crater in Ukraine, and Red Wing crater in North Dakota.
Kelley had developed a technique to precisely date impact craters, using laser argon-argon dating of the glass formed by the impacts, and he and Kelley sought Rowley's help to determine how the craters were aligned when the impacts occurred, since due to plate tectonics, the locations have moved large distances in the intervening 214 million years.
Three of the craters - Rochechouart, Manicouagan and Saint Martin - formed a 5,000 km (3,100 mi) chain at latitude 22.8° N, while Obolon' and Red Wing lay on identical declination paths with Rochechouart and Saint Martin respectively. All of the craters had previously been known and studied, but their paleoalignment had never before been demonstrated. Rowley has said that the chance that these craters could be aligned like this due to chance are nearly zero.[2]
Notes
- ^ "Saint Martin". Earth Impact Database. Planetary and Space Science Centre University of New Brunswick Fredericton. Retrieved 2008-12-30.
- ^ Steele, Diana (19 March 1998), "Crater chain points to impact of fragmented comet", University of Chicago Chronicle
External links
51°47′N 98°32′W / 51.783°N 98.533°W
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