The Mountain Lake cluster is a group of two diatremes in Northern Alberta, Canada. It formed during a period of kimberlite volcanism about 77 million years ago.[1] Other nearby kimberlite clusters include the Birch Mountains kimberlite field and the Buffalo Head Hills kimberlite field.
The pipes were discovered in 1989-90 just north of Mountain Lake which lies northeast of Grande Prairie, Alberta. Mountain Lake south pipe is 400 by 650 m. (29 ha) and the north pipe measures 250 by 350 m (8.75 ha). The pipes are alkaline ultramafic volcanics rather than archetypical kimberlites.[2]
Palynological evidence from clasts and laminated lacustrine sediments suggest an age of from 68 to 76 Ma for the two pipes. Fission track dating of apatite give ages of 72 to 78 Ma.[2]