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Liard Formation

Liard Formation
Stratigraphic range: Middle Triassic to Late Triassic
TypeGeological formation
UnderliesCharlie Lake Formation
Garbutt Formation
Buckinghorse Formation
OverliesToad Formation
Thicknessup to about 420 metres
(1370 ft)[1][2]
Lithology
PrimarySandstone, siltstone
OtherLimestone, dolomite
Location
Coordinates59°16′35″N 125°14′22″W / 59.276461°N 125.239326°W / 59.276461; -125.239326 (Liard Formation)
Region British Columbia
Country Canada
Type section
Named forLiard River
Named byE.D. Kindle, 1946

The Liard Formation is a stratigraphic unit of Middle Triassic to Late Triassic age in the Western Canadian Sedimentary Basin that is present in northeastern British Columbia. It takes its name from the Liard River, and was first described from outcrops on the southern bank of that river, near Hell Gate Rapids in the Grand Canyon of the Liard, by E.D. Kindle in 1946.[2][3]

The Liard Formation contains marine index fossils that define its age, but it is less fossiliferous than the underlying Toad Formation.[4] A very diverse ichnofossil assemblage is also known from the upper part of the formation.[5]

Lithology

The Liard Formation is composed of dolomitic to calcareous sandstone and siltstone, with minor thin beds of dolomite and bioclastic limestone. The limestone becomes cherty south of the Peace River. [1][2]

Distribution

The Liard Formation extends from the Liard River to the Pine River in the foothills of the Northern Rockies in northeastern British Columbia. It reaches a maximum thickness of about 420 metres (1370 ft) in the Williston Lake area.[1][2]

Relationship to other units

The Liard Formation overlies the Toad Formation, and the contact is conformable in most areas. It is conformably overlain by the Charlie Lake Formation in the southern part of its extent. To the north in the Liard River area, it is unconformably overlain by the Garbutt Formation and Buckinghorse Formation. It is laterally equivalent to the Halfway Formation in the subsurface of the Peace River plains, and to the upper part of the Llama Member of the Sulphur Mountain Formation in the southern Canadian Rockies and their foothills.[4]

References

  1. ^ a b c Lexicon of Canadian Geologic Units. "Liard Formation". Retrieved 2010-02-01.
  2. ^ a b c d 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.
  3. ^ Kindle, E.D., 1946. The Middle Triassic of Liard River, British Columbia, Appendix I. In: A Middle Triassic (Anisian) fauna in Halfway, Sikanni Chief, and Tetsa valleys, northeastern British Columbia. Geological Survey of Canada, Paper 46-1, 2nd ed. 1948.
  4. ^ a b Gibson, D.W., 1975. Triassic rocks of the Rocky Mountain Foothills and Front Ranges of northeastern British Columbia and west-central Alberta. Geological Survey of Canada, Bulletin 247, 61 p.
  5. ^ Zonneveld, John-Paul; Gingras, Murray K.; Pemberton, S. G. (15 February 2001). "Trace fossil assemblages in a Middle Triassic mixed siliciclastic-carbonate marginal marine depositional system, British Columbia". Palaeogeography, Palaeoclimatology, Palaeoecology. 166 (3–4): 249–276. Bibcode:2001PPP...166..249Z. doi:10.1016/S0031-0182(00)00212-1. Retrieved 20 January 2023.
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