Whitehorse Formation (Canada)

For other uses, see Whitehorse Formation.

Whitehorse Formation Stratigraphic range: Late Triassic PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Spray River Group
Sub-units	Winnifred Member Brewster Limestone Olympus Sandstone Lentil Starlight Evaporite Member
Underlies	Fernie Formation
Overlies	Sulphur Mountain Formation
Thickness	Up to 500 metres (1,640 ft) [1]
Lithology
Primary	Limestone, dolomite
Other	Sandstone, gypsum
Location
Coordinates	52°59′5″N117°20′48″W / 52.98472°N 117.34667°W / 52.98472; -117.34667 (Whitehorse Formation) Coordinates: 52°59′5″N117°20′48″W / 52.98472°N 117.34667°W / 52.98472; -117.34667 (Whitehorse Formation)
Region	Alberta   British Columbia
Country	Canada
Type section
Named for	Whitehorse Creek
Named by	P.S. Warren [2]
Year defined	1945

The Whitehorse Formation is a geologic formation of Late Triassic age. It is present on the western edge of the Western Canada Sedimentary Basin in western Alberta and northeastern British Columbia. It was first described as a member of the Spray River Formation by P.S. Warren in 1945, ^[2] who named it for Whitehorse Creek, a tributary of the McLeod River south of Cadomin, Alberta. It was later raised to formation status. ^[3]

Marine fossils from the Late Triassic epoch including crinoids, brachiopods, bivalves, and gastropods, have been found in the Whitehorse Formation. ^{[3] [4]}

Lithology and stratigraphy

The Whitehorse Formation was deposited on the continental shelf along the western margin of the North American craton. ^{[3] [4] [5]} It consists of dolomite, limestone, quartzose sandstone, and siltstone, with minor gypsum. ^{[1] [3]}

The Whitehorse Formation is subdivided into the following members: ^{[3] [4]}

Geological Unit	Age	Lithology	Thickness	Reference
Winnifred Member	Late Triassic	Grey silty to sandy quartzose dolomite, with minor beds of quartz siltstone	4 – 44 m (12 – 145 ft)	[3]
Brewster Limestone Member	Late Triassic	Grey, cliff-forming fossiliferous limestone with local interbeds of silty to sandy dolomite	0 – 63 m (0 – 207 ft)	[1]
Starlight Evaporite Member	Late Triassic	Interbedded dolomite, limestone, sandstone, siltstone, and minor gypsum	6 – 402 m (20 – 1320 ft)	[3]
Olympus Sandstone lentil	Late Triassic	Cliff-forming, slightly dolomitic quartz sandstone and, locally, sandy dolomite	0 – 140 m (0 – 457 ft)	[3]

Distribution and relationship to other units

The Whitehorse Formation is present in the Rocky Mountains and their foothills from the Canada–United States border in Alberta to the Sukunka River area of northeastern British Columbia. It is disconformably overlain by the Jurassic Fernie Formation and conformably underlain by the Sulphur Mountain Formation. It is correlative with the Charlie Lake, Ludington, Baldonnel and lower Pardonet Formations and, in the subsurface of northeastern British Columbia, the Schooler Creek Group. ^[1]

Economic resources

Gypsum

Although localized deposits of gypsum are present in the Starlight Evaporite Member, they lie within Jasper National Park and are protected from development. ^[3]

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. Warren, P.S. 1945. Triassic faunas in the Canadian Rockies. American Journal of Science, vol. 243, no. 9, p. 480-491; doi: 2475/ajs.243.9.480.
3. Gibson, D.W. 1974. Triassic rocks of the southern Canadian Rocky Mountains. Geological Survey of Canada, Bulletin 230, 65 p.
4. Gibson, D.W. and Edwards, D.E. 1990. An overview of Triassic stratigraphy and depositional environments in the Rocky Mountain Foothills and Western Interior Plains, Peace River Arch area, northeastern British Columbia. Bulletin of Canadian Petroleum Geology, vol. 38A, p. 146-158.
5. Edwards, D.E., Barclay, J.E., Gibson, D.W., Kvill, G.E. and Halton, E. (1994). "Triassic strata of the Western Canada Sedimentary Basin, Chapter 16 of The Geological Atlas of the Western Canada Sedimentary Basin, Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists and Alberta Geological Survey" . Retrieved 2018-02-19.