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Ishbel Group

Ishbel Group
Stratigraphic range: Permian
Calcareous siltstone exposed along the Johnston Creek west of Banff
TypeGroup
UnderliesSpray River Group
OverliesTunnel Mountain Formation, Kananaskis Formation
ThicknessUp to about 425 m (1,394 ft)[1]
Lithology
PrimaryLimestone, dolomite, sandstone
OtherChert, siltstone
Location
Region Alberta
 British Columbia
Country Canada
ExtentWestern Canadian Sedimentary Basin
Type section
Named forMount Ishbel
Named byA. McGugan
Year defined1963

The Ishbel Group is a stratigraphic unit of Permian age in the Western Canadian Sedimentary Basin. It is present in the Canadian Rockies of Alberta and British Columbia. First defined by A. McGugan in 1963,[2] it is named for Mount Ishbel of the Sawback Range in Banff National Park, and parts of the group were first described in the vicinity of the mountain at Ranger Canyon and Johnston Canyon.[3]

Lithology

The Ishbel Group is composed of carbonate rocks (limestone and dolomite) and sandstone, with minor chert and siltstone. [1][3] Depositional conditions were similar to those of the Phosphoria Formation to the south in United States.[3]

Paleontology

Among the fossils that have been found in the Ishbel Group are corals, bryozoa, crinoids, and conodonts,[3] as well as productid, chonetid and spiriferid brachiopods, omphalotrochid gastropods, and edestid elasmobranch fish.[4]

Distribution

The Ishbel Group reaches a maximum thickness of up to about 425 metres (1400 ft). It is present in the front ranges of the Canadian Rockies as far north as the Peace River.[1][3]

Subdivisions

Sub-unit Age Lithology Max.
Thickness		 Reference
Kindle Formation Asselian to early Artinskian siltstone, shale 200 m (660 ft) [5]
Belloy Formation Permian limestone, dolomite, and sandstone 274 m (900 ft) [6]
Fantasque Formation Permian spicular chert, shale, and siltstone 55 m (180 ft) [7]
Mowitch Formation Roadian to Wordian sandstone with gypsum 76 m (250 ft) [8]
Ranger Canyon Formation Roadian to Wordian dark chert, silicified sandstone, evaporite minerals 30 m (100 ft) [9]
Ross Creek Formation late Sakmarian to Artinskian shaly siltstone, calcareous siltstone, silty carbonate, phosphatic coquinas 143 m (470 ft) [10]
Telford Formation Asselian to Sakmarian sandy limestone and dolomite 259 m (850 ft) [11]
Johnston Canyon Formation late Sakmarian to Artinskian phosphatic siltstone, calcareous siltstone, and silty limestone and dolomite 57 m (190 ft) [12]
Belcourt Formation Asselian to Sakmarian silty dolomite with chert 130 m (430 ft) [13]

Relationship to other units

The Ishbel Group is disnconformably overlain by the Spray River Group and unconformably overlies the Tunnel Mountain Formation and the Kananaskis Formation.[1] It is partly equivalent to the Phosphoria Formation of Montana, Idaho, Wyoming, and Utah.[3]

References

  1. ^ a b c d Lexicon of Canadian Geologic Units. "Ishbel Group". Retrieved 2010-01-01.
  2. ^ McGugan, A., 1963. A Permian brachiopod and fusulinid fauna from Elk Valley, British Columbia, Canada. Journal of Paleontology, v. 37, p. 621-627.
  3. ^ a b c d e f 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.
  4. ^ Journal of Paleontology. "Biostratigraphy and faunas of the Permian Ishbel Group, Canadian Rocky Mountains". Retrieved 2010-01-10.
  5. ^ Lexicon of Canadian Geologic Units. "Kindle Formation". Retrieved 2010-01-09.
  6. ^ Lexicon of Canadian Geologic Units. "Belloy Formation". Archived from the original on 2012-07-08. Retrieved 2010-01-09.
  7. ^ Lexicon of Canadian Geologic Units. "Fantasque Formation". Retrieved 2010-01-09.
  8. ^ Lexicon of Canadian Geologic Units. "Mowitch Formation". Retrieved 2010-01-09.
  9. ^ Lexicon of Canadian Geologic Units. "Ranger Canyon Formation". Retrieved 2010-01-09.
  10. ^ Lexicon of Canadian Geologic Units. "Ross Creek Formation". Retrieved 2010-01-09.
  11. ^ Lexicon of Canadian Geologic Units. "Telford Formation". Retrieved 2010-01-09.
  12. ^ Lexicon of Canadian Geologic Units. "Johnston Canyon Formation". Retrieved 2010-01-09.
  13. ^ Lexicon of Canadian Geologic Units. "Belcourt Formation". Retrieved 2010-01-09.
Quelle: https://en.wikipedia.org/wiki/Fantasque_Formation