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Fort St. John Group

The Fort St. John Group is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin.[2] It takes the name from the city of Fort St. John, British Columbia and was first defined by George Mercer Dawson in 1881.

Lithology

The Fort St. John Group is mostly composed of dark shale deposited in a marine environment. Bentonite is present in the shale, and it is interbedded with sandstone, siltstone and conglomerates.

Distribution

The Fort St. John Group occurs in the subsurface in the Peace River Country of northeastern British Columbia and north-western Alberta, in southern Yukon and southern Northwest Territories. It has a thickness of 700 metres (2,300 ft) to 2,000 metres (6,560 ft).

Relationship to other units

The Fort St. John Group is conformably overlain by the Dunvegan Formation and conformably underlain by the Bullhead Group or may rest disconformably on older units.

Subdivisions

The Fort St. John Group is subdivided into the following formations:

Canadian Rockies foothills of British Columbia

Peace River Country

Liard River and Fort Liard Area

*Buckinghorse Formation is equivalent to the sum of Lepine Formation, Scatter Formation and Garbutt Formation. It occurs north-east of the Canadian Rockies foothills in British Columbia, between the Halfway River and Muskwa River. It is composed of silty marine mudstone with fine grained marine sandstone interbeds.

References

  1. ^ Lexicon of Canadian Geologic Units. "Fort St. John Group". Retrieved 2009-02-11.
  2. ^ Mossop, G.D. and Shetsen, I., (compilers), Canadian Society of Petroleum Geologists and Alberta Geological Survey (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 19: Cretaceous Mannville Group of the Western Canada Sedimentary Basin". Archived from the original on 2013-08-14. Retrieved 2013-08-01.{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. ^ Lexicon of Canadian Geologic Units. "Cruiser Formation". Retrieved 2009-02-11.
  4. ^ Lexicon of Canadian Geologic Units. "Goodrich Formation". Retrieved 2009-02-11.
  5. ^ Lexicon of Canadian Geologic Units. "Hasler Formation". Retrieved 2009-02-11.
  6. ^ Lexicon of Canadian Geologic Units. "Commotion Formation". Retrieved 2009-02-11.
  7. ^ Lexicon of Canadian Geologic Units. "Gates Formation". Retrieved 2009-02-11.
  8. ^ Lexicon of Canadian Geologic Units. "Moosebar Formation". Retrieved 2009-02-11.
  9. ^ Lexicon of Canadian Geologic Units. "Shaftesbury Formation". Retrieved 2009-02-11.
  10. ^ Lexicon of Canadian Geologic Units. "Peace River Formation". Archived from the original on 2012-07-08. Retrieved 2009-02-11.
  11. ^ Lexicon of Canadian Geologic Units. "Spirit River Formation". Retrieved 2009-02-11.
  12. ^ Lexicon of Canadian Geologic Units. "Bluesky Formation". Archived from the original on 2012-07-09. Retrieved 2009-02-11.
  13. ^ Lexicon of Canadian Geologic Units. "Sully Formation". Retrieved 2009-02-11.
  14. ^ Lexicon of Canadian Geologic Units. "Sikanni Formation". Retrieved 2009-02-11.
  15. ^ Lexicon of Canadian Geologic Units. "Lepine Formation". Retrieved 2009-02-11.
  16. ^ Lexicon of Canadian Geologic Units. "Scatter Formation". Retrieved 2009-02-11.
  17. ^ Lexicon of Canadian Geologic Units. "Garbutt Formation". Retrieved 2009-02-11.
  18. ^ Lexicon of Canadian Geologic Units. "Chinkeh Formation". Retrieved 2010-01-09.