The Mountain Lake cluster is a group of two diatreme

Diatreme

A diatreme is a breccia-filled volcanic pipe that was formed by a gaseous explosion. Diatremes often breach the surface and produce a tuff cone, a filled relatively shallow crater known as a maar, or other volcanic pipes.- Word origin :...

s in Northern Alberta

Northern Alberta

Northern Alberta is a region located in the Canadian province of Alberta.Its primary industry is oil and gas, with large heavy oil reserves being exploited at the Athabasca Oil Sands and Wabasca Area in the east of the region...

, Canada

Canada

Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...

. It formed during a period of kimberlite

Kimberlite

Kimberlite is a type of potassic volcanic rock best known for sometimes containing diamonds. It is named after the town of Kimberley in South Africa, where the discovery of an diamond in 1871 spawned a diamond rush, eventually creating the Big Hole....

 volcanism about 77 million years ago. Other nearby kimberlite clusters include the Birch Mountains kimberlite field

Birch Mountains kimberlite field

The Birch Mountains kimberlite field is a kimberlite field in Northern Alberta, Canada. It is a product of kimberlite volcanism during the Cretaceous period which was the most prolific period for worldwide kimberlite volcanism...

 and the Buffalo Head Hills kimberlite field

Buffalo Head Hills kimberlite field

The Buffalo Head Hills kimberlite field is a kimberlite field in north-central Alberta, Canada. It is a product of kimberlite volcanism during the Cretaceous period which was the most prolific period for worldwide kimberlite volcanism...

.

The pipes were discovered in 1989-90 just north of Mountain Lake which lies northeast of Grande Prairie, Alberta

Grande Prairie, Alberta

Grande Prairie is a city in the northwestern part of the province of Alberta in Western Canada. It is located on the southern edge of the Peace River Country . The city is surrounded by the County of Grande Prairie No...

. 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.

Palynological

Palynology

Palynology is the science that studies contemporary and fossil palynomorphs, including pollen, spores, orbicules, dinoflagellate cysts, acritarchs, chitinozoans and scolecodonts, together with particulate organic matter and kerogen found in sedimentary rocks and sediments...

 evidence from clasts and laminated lacustrine

Lake

A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

 sediments suggest an age of from 68 to 76 Ma for the two pipes. Fission track dating

Fission track dating

Fission track dating is a radiometric dating technique based on analyses of the damage trails, or tracks, left by fission fragments in certain uranium-bearing minerals and glasses...

 of apatite

Apatite

Apatite is a group of phosphate minerals, usually referring to hydroxylapatite, fluorapatite, chlorapatite and bromapatite, named for high concentrations of OH−, F−, Cl− or Br− ions, respectively, in the crystal...

 give ages of 72 to 78 Ma.

See also

• Volcanism of Canada
• Volcanism of Western Canada
  Volcanism of Western Canada
  Volcanism of Western Canada produces lava flows, lava plateaus, lava domes, cinder cones, stratovolcanoes, shield volcanoes, submarine volcanoes, calderas, diatremes and maars, along with examples of more less common volcanic forms such as tuyas and subglacial mounds.-Volcanic belts:*Anahim...