Lynx Formation Explained

The Lynx Formation or Lynx Group is a stratigraphic unit of Late Cambrian (Dresbachian) age in the Western Canada Sedimentary Basin.^[1] It is present in the Canadian Rockies of Alberta and British Columbia. It was originally described as the Lynx Formation by Charles Doolittle Walcott in 1913, based on and named for outcrops on the slopes of Lynx Mountain on the continental divide east of Mount Robson. It was subdivided into five formations and elevated to group status by J.D. Aitken and R.G. Greggs in 1967.^[2] The name Lynx Formation continues to be used in areas where some or all of the subdivisions cannot be distinguished. All of the formations in the Lynx Group include fossil trilobites and some contain the stromatolite Collenia.

Lithology and deposition

The Lynx Group is composed alternating zones of carbonate rocks, most of which are dolomitic, and shales.^[3] It was deposited in shallow marine environments along the western margin of the North American Craton during Late Cambrian time.^[4] In many areas it is subdivided into the five formations listed below.^{[5] [6]}

Subdivisions

Upper Lynx Group

Formation	Lithology	Max. Thickness	Reference
	carbonate rocks, minor cherty layers	158-1NaN-1
	green and grey shales, argillaceous limestone	203-1NaN-1
	massive cliff-forming carbonate rocks	519-1NaN-1

Lower Lynx Group

Formation	Lithology	Max. Thickness	Reference
	grey, green, and brown shales, argillaceous limestone	424-1NaN-1
		183-1NaN-1

Distribution

The Lynx Group is present in the Canadian Rockies of Alberta and British Columbia. It is typically between 1068-1220 metres (3500-400 feet) thick in the front and main ranges. It extends as far north as the Monkman Pass area of British Columbia.

Relationship to other units

The Lynx Group overlies the Arctomys Formation and the contact is gradational. It is overlain by the Survey Peak Formation and the contact is concordant but abrupt.

Notes and References

1. Web site: The Geological Atlas of the Western Canada Sedimentary Basin (Mossop, G.D. and Shetsen, I., compilers), Chapter 8: Middle Cambrian and Early Ordovician Strata of the Western Canada Sedimentary Basin. Slind, O.L., Andrews, G.D., Murray, D.L., Norford, B.S., Paterson, D.F., Salas, C.J., and Tawadros, E.E., Canadian Society of Petroleum Geologists and Alberta Geological Survey. 1994. 2018-07-13.
2. Aitken, J. D and Greggs, R G., 1967. Upper Cambrian formations, southern Rocky Mountains of Alberta, an interim report. Geological Survey of Canada, Paper 66-49.
3. Web site: Lynx Formation. . 2010-02-01.
4. Aitken, J.D. 1966. Middle Cambrian to Middle Ordovician cyclic sedimentation, southern Rocky Mountains of Alberta. Bulletin of Canadian Petroleum Geology, vol. 14, no. 6, p. 405-441.
5. Glass, D.J. (editor) 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada including eastern British Columbia, Alberta, Saskatchewan and southern Manitoba. Canadian Society of Petroleum Geologists, Calgary, 1423 p. on CD-ROM. .
6. Web site: Alberta Geological Survey . Alberta Table of Formations, May 2019 . Alberta Energy Regulator . 24 March 2020.