Outram Formation

Outram Formation
Stratigraphic range: Early Ordovician ~485–470  Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Formation
Underlies	Skoki Formation
Overlies	Survey Peak Formation
Thickness	Up to 443 metres (1453 ft) [1]
Lithology
Primary	Limestone, siltstone
Other	Shale, chert
Location
Coordinates	51°52′54″N116°52′31″W / 51.88167°N 116.87528°W / 51.88167; -116.87528 (Outram Formation)
Region	Canadian Rockies
Country	Canada
Type section
Named for	Mount Outram
Named by	J.D. Aitken and B.S. Norford [2]

The Outram Formation is a stratigraphic unit of Early Ordovician age that is present on the western edge of the Western Canada Sedimentary Basin in the Canadian Rockies of Alberta and British Columbia. ^[3] It was named for Mount Outram in Banff National Park by J.D. Aitken and B.S. Norford in 1967. ^[2] The Outram Formation is fossiliferous and includes remains of trilobites and other marine invertebrates, as well as stromatolites and thrombolites. ^{[1] [2]}

Lithology and deposition

The Outram Formation formed as a shallow and at times emergent marine shelf along the western shoreline of the North American Craton during Early Ordovician time. ^{[2] [3]} It consists primarily of nodular limestone, calcareous quartzose siltstone, limestone pebble-conglomerate, and brown shale. Nodules of grey chert occur throughout the formation. ^{[1] [2]}

Distribution and stratigraphic relationships

The Outram is present in the Rocky Mountains of Alberta and British Columbia. Its thickness and shale content increase toward the west. ^{[1] [2]} It overlies the Survey Peak Formation and underlies the Skoki Formation. ^[4] Both contacts are gradational. ^{[1] [2]}

Paleontology

The Outram Formation contains several genera of trilobites, as well as brachiopods, conodonts, gastropods, sponges, echinoderms, bivalves, gastropods, stromatolites, thrombolites, oncolites, rare graptolites, and others. ^{[1] [2]}

References

1. 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. ISBN   0-920230-23-7.
2. Aitken, J.D. and Norford, B.S. 1967. Lower Ordovician Survey Peak and Outram formations, southern Rocky Mountains of Alberta. Bulletin of Canadian Petroleum Geology, vol. 15, p. 150-207.
3. 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). "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". Archived from the original on 2016-07-01. Retrieved 2018-07-13.
4. Alberta Geological Survey. "Alberta Table of Formations, May 2019" (PDF). Alberta Energy Regulator. Retrieved 24 March 2020.