Outram Formation
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]
| Outram Formation Stratigraphic range: Early Ordovician ~485–470 Ma | |
|---|---|
| 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″N 116°52′31″W |
| Region | Canadian Rockies |
| Country | .svg.png.webp){kind=small} |
| Type section | |
| Named for | Mount Outram |
| Named by | J.D. Aitken and B.S. Norford[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
- 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.
- 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.
- 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.CS1 maint: multiple names: authors list (link)
- Alberta Geological Survey. "Alberta Table of Formations, May 2019" (PDF). Alberta Energy Regulator. Retrieved 24 March 2020.