[Steve Van Doorn]

Yellowstone Caldera is moving east. I believe it started under Wallowa-Whitman National forest moved south to the Craters of the moon national preserve then up to where it is now. Generally going around the mountains.

12,600 years ago likely the Saginaw Michigan Impact Structure or massive solar flare/micro-Nova that caused the younger dryas. I don't know of any Caldera under that area.

[Cletus.D.Yokel]

Oil and gas production comes from an ancient coral reef (scipio limestone).
The reef is in the shape of a horseshoe beginning in Rogers City moving west toward Pellston where an arc begins in Lake Michigan.
It curves around toward Allegan and terminating in Calhoun County.

It is a classic atoll reef.