Edmonton Group

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Edmonton Group
Stratigraphic range: Late Cretaceous to Early Paleocene
Horseshoe Canyon Alberta Nov 1988.jpg
Horseshoe Canyon Formation of the Edmonton Group
Type Geological group
Sub-units Scollard Formation, Battle Formation, Whitemud Formation, Horseshoe Canyon Formation
Underlies Paskapoo Formation
Overlies Bearpaw Formation, Belly River Group
Thickness328 metres (1,076 ft) to 763 metres (2,503 ft) [1]
Lithology
Primary Sandstone, shale
Other Bentonite, coal
Location
Region Alberta
CountryCanada
Type section
Named for Edmonton
Named by Joseph Tyrrell, 1887

Within the earth science of geology, the Edmonton Group is a Late Cretaceous (Campanian stage) to early Paleocene stratigraphic unit of the Western Canada Sedimentary Basin in the central Alberta plains. [2] It was first described as the Edmonton Formation by Joseph Burr Tyrrell in 1887 based on outcrops along the North Saskatchewan River in and near the city of Edmonton. [3] E.J.W. Irish later elevated the formation to group status and it was subdivided into four separate formations. [4] In ascending order, they are the Horseshoe Canyon, Whitemud, Battle and Scollard Formations. [2] [1] The Cretaceous-Paleogene boundary occurs within the Scollard Formation, based on dinosaurian and microfloral evidence, [5] as well as the presence of the terminal Cretaceous iridium anomaly. [6]

Contents

Distribution and thickness

The Edmonton Group is present in the central plains of Alberta. It consists of sedimentary rocks that were deposited in nonmarine to brackish water environments between the Canadian Rockies in the west and the Western Interior Seaway to the east. [2] Its reaches a maximum thickness of 763 metres (2,503 ft) near the foothills of the Rockies in the west, and thins eastward to zero at its erosional edge east of Edmonton. [1]

Lithology

The Edmonton Group consists of fine-grained sandstones, calcareous sandstones, siltstones, sandy shales and mudstones, bentonitic sandstones and shales, bentonite beds, ironstone concretions, carbonaceous shales and coal seams. Hard sandstones commonly cap mesas, buttes and plateaus where erosion has formed badlands topography, as is the case for much of the Horseshoe Canyon Formation and the Scollard Formation. Coarse-grained sediments are rare in the Edmonton Group. [1]

Paleontology

Plant fossils are common in both the Late Cretaceous and early Paleocene portions of the Edmonton Group. [7] Remains of Triceratops and other dinosaurs are found in the Late Cretaceous portion, especially the Horseshoe Canyon Formation and the lower part of the Scollard Formation. Molluscs such as Ostrea and Unio are found in both portions. [1]

Relationship to other units

The Edmonton Group is disconformably overlain by the Paskapoo Formation and conformably overlies the Bearpaw Formation or, where the Bearpaw is absent, the Belly River Formation. [1]

The Edmonton Group grades into the sequence of the Blood Reserve Formation, St. Mary River Formation and Willow Creek Formation in the southern Alberta plains; into the upper part of the Wapiti Group in the northern Alberta and northeastern British Columbia; and into the upper part of the Brazeau Formation and the Coalspur Formation in the foothills of the Canadian Rockies. It is equivalent to, but not contiguous with, the Eastend Formation, Whitemud Formation, Battle Formation and Frenchman Formation in the Cypress Hills of southeastern Alberta and southwestern Saskatchewan; and with the Fox Hills Formation in Saskatchewan. [2] [1]

Formations that are stratigraphically equivalent in the western United States are the Horsethief Formation in Montana; the Fox Hills Formation and Lance Formation in Montana; and the Lennup Formation and Muteetse Formation in Wyoming. [1]

Subdivisions

The formations of the Edmonton Group are:

Formation Age LithologyMaximum
Thickness		Reference
Scollard Maastrichtian-Paleocene sandstone, siltstone, mudstone, coal400 m (1,310 ft) [1]
Battle Formation Maastrichtianbentonitic silty shale, montmorillonitic clay 14 m (50 ft) [1]
Whitemud Maastrichtian kaolinitic sandstone, clay, shale23 m (80 ft) [1]
Horseshoe Canyon Campanian-Maastrichtiansandstone, siltstone, mudstone, coal227 m (740 ft) [1]

See also

Related Research Articles

<span class="mw-page-title-main">Horseshoe Canyon Formation</span> Geological formation in Canada

The Horseshoe Canyon Formation is a stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. It takes its name from Horseshoe Canyon, an area of badlands near Drumheller.

<span class="mw-page-title-main">Scollard Formation</span> Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin

The Scollard Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in southwestern Alberta. Its deposition spanned the time interval from latest Cretaceous to early Paleocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It is significant for its fossil record, and it includes the economically important coal deposits of the Ardley coal zone.

The Frenchman Formation is stratigraphic unit of Late Cretaceous age in the Western Canada Sedimentary Basin. It is present in southern Saskatchewan and the Cypress Hills of southeastern Alberta. The formation was defined by G.M. Furnival in 1942 from observations of outcrops along the Frenchman River, between Ravenscrag and Highway 37. It contains the youngest of dinosaur genera, much like the Hell Creek Formation in the United States.

<span class="mw-page-title-main">Bearpaw Formation</span> Geologic formation in North America

The Bearpaw Formation, also called the Bearpaw Shale, is a geologic formation of Late Cretaceous (Campanian) age. It outcrops in the U.S. state of Montana, as well as the Canadian provinces of Alberta and Saskatchewan, and was named for the Bear Paw Mountains in Montana. It includes a wide range of marine fossils, as well as the remains of a few dinosaurs. It is known for its fossil ammonites, some of which are mined in Alberta to produce the organic gemstone ammolite.

The Belly River Group is a stratigraphical unit of Late Cretaceous age in the Western Canadian Sedimentary Basin.

<span class="mw-page-title-main">Foremost Formation</span> Geologic formation in Alberta, Canada

The Foremost Formation is a stratigraphic unit of Late Cretaceous (Campanian) age that underlies much of southern Alberta, Canada. It was named for outcrops in Chin Coulee near the town of Foremost and is known primarily for its dinosaur remains and other fossils.

The Wapiti Formation is a geological formation of the Western Canada Sedimentary Basin in northwestern Alberta, and northeastern British Columbia, Canada. Its deposition spanned the time interval from the lower Campanian through to the upper Maastrichtian, between approximately 80 and 68 Ma. It was named by G.M. Dawson in 1881, presumably for exposures along the lower part of the Wapiti River and downstream along the Smoky River in Alberta.

<span class="mw-page-title-main">St. Mary River Formation</span> Geologic formation in western Canada

The St. Mary River Formation is a geologic formation of Late Cretaceous age of the Western Canada Sedimentary Basin in southwestern Alberta and northwesternmost Montana. It was first described from outcrops along the St. Mary River by George Mercer Dawson in 1883, and it takes its name from the river.

The Willow Creek Formation is a stratigraphic unit of Late Cretaceous to Early Paleocene age in the Western Canada Sedimentary Basin of southwestern Alberta. It was first described by George Mercer Dawson in 1883 along the Willow Creek, a tributary of the Oldman River. Williams and Dyer defined the type section in 1930 at the mouth of Willow Creek, east of Fort Macleod.

Gething Formation is a stratigraphic unit of Lower Cretaceous (Aptian) age in the Western Canada Sedimentary Basin. It is present in northeastern British Columbia and western Alberta, and includes economically important coal deposits.

Bullhead Group is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin of northeastern British Columbia and western Alberta. It was first defined by F.H. McLearn in 1918 as the Bullhead Mountain Formation, but later was upgraded to group status. It consists of the Cadomin and Gething Formations, although some early workers included the Bluesky Formation and others in the group.

The Ellerslie Member is a stratigraphic unit of Early Cretaceous age in the Western Canadian Sedimentary Basin.

<span class="mw-page-title-main">Paskapoo Formation</span> Stratigraphic unit in Western Canada

The Paskapoo Formation is a stratigraphic unit of Middle to Late Paleocene age in the Western Canada Sedimentary Basin. The Paskapoo underlies much of southwestern Alberta, and takes the name from the Blindman River. It was first described from outcrops along that river, near its confluence with the Red Deer River north of the city of Red Deer, by Joseph Tyrrell in 1887. It is important for its freshwater aquifers, its coal resources, and its fossil record, as well as having been the source of sandstone for the construction of fire-resistant buildings in Calgary during the early 1900s.

The Wapiti Group is a stratigraphical unit of Cretaceous age in the Western Canadian Sedimentary Basin. It has formation status in Alberta and group status in British Columbia.

The Ravenscrag Formation is a stratigraphic unit of early Paleocene age in the Western Canada Sedimentary Basin. It was named for the settlement of Ravenscrag, Saskatchewan, and was first described from outcrops at Ravenscrag Butte near the Frenchman River by N.B. Davis in 1918.

The Eastend Formation is a stratigraphical unit of Maastrichtian age in the Western Canadian Sedimentary Basin. It takes its name from the town of Eastend, Saskatchewan, and was first described in outcrop around the settlement by L.S. Russell in 1932. The type locality was later defined south-west of the town by W.O. Kupsch in 1956.

The Coalspur Formation is an Upper Cretaceous to lower Palaeocene stratigraphic unit of the Western Canada Sedimentary Basin in the foothills of southwestern Alberta. Its deposition spanned the time interval from latest Cretaceous (Maastrichtian) to early Palaeocene, and it includes sediments that were deposited before, during, and after the Cretaceous-Paleogene (K-Pg) extinction event. It includes the economically important coal deposits of the Coalspur Coal Zone, as well as nonmarine plant and animal fossils.

The Battle Formation is a geologic formation of Late Cretaceous (Maastrichtian) age in the Western Canada Sedimentary Basin. It is present throughout much of the central Alberta plains, where it is an important stratigraphic marker in the nonmarine Upper Cretaceous sequence. It was formally named by G.M. Furnival in 1942 and given formation status by E.J.W. Irish in 1970.

The Whitemud Formation is a geologic formation of Late Cretaceous (Maastrichtian) age in the Western Canada Sedimentary Basin. it is present through the plains of southern Saskatchewan, southeastern Alberta and south-central Alberta. Named by N.B. Davis in 1918, the formation is characterized by white kaolinitic clay and is a source of high-quality refractory clay. The type locality has been designated as Dempster's clay pit northwest of Eastend, Saskatchewan.

<span class="mw-page-title-main">Blood Reserve Formation</span> Geologic formation of Late Cretaceous age in the Western Canada Sedimentary Basin

The Blood Reserve Formation, also known as the Blood Reserve Sandstone, is a geologic formation of Late Cretaceous (Campanian) age in the Western Canada Sedimentary Basin. It is present in southwestern Alberta, Canada, and was named for Blood Indian Reserve No. 148 by L.S. Russell in 1932. It is an aquifer and a source of fresh groundwater.

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 Glass, D.J., editor, 1997. Lexicon of Canadian Stratigraphy, vol. 4, Western Canada. Canadian Society of Petroleum Geologists, Calgary, Alberta,1423 p. on CD-ROM, ISBN   0-920230-23-7.
  2. 1 2 3 4 Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists (1994). "The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 24: Upper Cretaceous and Tertiary strata of the Western Canada Sedimentary Basin" . Retrieved 2016-06-20.{{cite web}}: CS1 maint: multiple names: authors list (link)
  3. ↑ Tyrrell, J.B., 1887. Report on a part of northern Alberta and portions of adjacent Districts of Assiniboia and Saskatchewan. Geological Survey of Canada, Ann. Rept.1886, new ser., v.11, Part E, p.1-176.
  4. ↑ Irish, E.J.W. 1970. The Edmonton Group of south-central Alberta. Bulletin of Canadian Petroleum Geology, vol. 18, p. 125-155.
  5. ↑ Lerbekmo, J.F., Singh, C., Jarzen, D.M., and Russel, D.A. 1979. The Cretaceous-Tertiary boundary in south-central Alberta - a revision based on dinosaurian and microfloral evidence. Canadian Journal of Earth Science, 16: 325-330.
  6. ↑ Lerbekmo, J.F. and St. Louis, R.M. 1985. The terminal Cretaceous iridium anomaly in the Red Deer Valley, Alberta. Canadian Journal of Earth Science, 23: 120-124.
  7. ↑ Bell, W.A. 1949. Uppermost Cretaceous and Paleocene floras of western Canada. Geological Survey of Canada, Bulletin 13, 231 p.
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