| Saint Martin impact structure | |
|---|---|
  Location of the impact structure in Canada | |
| Impact crater/structure | |
| Confidence | Confirmed |
| Diameter | 40 km (25 mi) |
| Age | 227.8 ± 1.1 Ma Carnian |
| Exposed | No |
| Drilled | Yes |
| Location | |
| Coordinates | 51°47′N98°32′W / 51.783°N 98.533°W /51.783; -98.533 |
| Country | Canada |
| Province | Manitoba |
| Municipality | Grahamdale |
Saint Martin is animpact structure inManitoba, Canada.[1] It is located in the northern part of theRural Municipality of Grahamdale, northwest ofLake St. Martin.
The impact structure is 40 km (25 mi) in diameter and its age was determined to be 227.8 ± 1.1 million years[2] (Carnian stage of theTriassic) using theargon-argon dating technique. The crater is well preserved but poorly exposed at the surface as the whole region is covered by glacial drift.
It had previously been suggested byGeophysicist David Rowley of theUniversity of Chicago, working with John Spray of theUniversity of New Brunswick and Simon Kelley of theOpen University, that the Saint Martin structure may have been part of a hypothetical multiple impact event which also formed theManicouagan impact structure in northernQuebec,Rochechouart impact structure in France,Obolon' crater inUkraine, andRed Wing crater inNorth Dakota.[3] All of the impact structures had previously been known and studied, but their paleoalignment had never before been demonstrated. Rowley has said that the chance that these structures could be aligned like this due to chance are nearly zero.[4] However, more recent work has found that the craters formed many millions of years apart, with the Saint Martin crater dating to 227.8 ± 1.1 Ma,[5] while the Rochechouart structure formed 206.92 ± 0.20/0.32 Ma.[6]
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