imported>Volcanoguy: removed Category:Conglomerate formations; added Category:Conglomerate formations of Canada using HotCat

2025-06-20T20:13:18Z

removed Category:Conglomerate formations; added Category:Conglomerate formations of Canada using HotCat

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{{Short description|Geological formation in Canada}}
{{Infobox Rockunit
| name = Cadomin Formation
| image = Cadomin Formation 2 Preview.jpg
| caption = Cadomin Formation [[outcrop]]s, Centennial Ridge Trail, [[Mount Allan (Canada)|Mount Allan]], [[Kananaskis Country|Kananaskis]], [[Alberta]]
| type = [[Geological formation]]
| age = {{Fossil range|Early Cretaceous|Early Cretaceous|[[Early Cretaceous]]}}
| period = Early Cretaceous
| prilithology = [[Conglomerate (geology)|Conglomerate]], [[sandstone]]
| otherlithology = [[Shale]], [[coal]]
| namedfor = [[Cadomin, Alberta]]
| namedby = B.R. Mackay<ref>Mackay, B.R., 1930. Stratigraphy and structure of bituminous coal fields in the vicinity of Jasper Park, Alberta. Can. Inst. Min. and Metall., Trans., v. 33, p. 473-509.</ref>
| region = [[Alberta]]<br>[[British Columbia]]
| country = [[Canada]]
| coordinates = {{coord|53|00|N|117|19|W|name=Cadomin Formation|display=inline,title}}
| unitof = [[Bullhead Group]], [[Blairmore Group]], [[Luscar Group]]
| subunits =
| underlies = [[Gething Formation]], [[Gladstone Formation]]
| overlies = [[Kootenay Group]], [[Nikanassin Formation]], [[Minnes Group]], [[Fernie Group]]
| thickness = up to more than {{convert|170|m|ft}}<ref name=Glass />
| extent =
| area =
| map =
}}
The '''Cadomin Formation''' is a [[stratigraphic unit]] of [[Early Cretaceous]] ([[Barremian]] to [[Aptian]]) age in the western part of the [[Western Canadian Sedimentary Basin|Western Canada Sedimentary Basin]].<ref name=Mossop19 /> It is extends from southeastern [[British Columbia]] through western [[Alberta]] to northeastern British Columbia, and it contains significant [[petroleum reservoir|reservoirs]] of [[natural gas]] in some areas. It was named after the mining town of [[Cadomin, Alberta|Cadomin]], which is an [[acronym]] of "Canadian Dominion Mining".<ref>Alberta Speleological Society. [http://www.caving.ab.ca/cadomin_cave.htm Cadomin Cave] {{webarchive|url=https://web.archive.org/web/20090418181600/http://www.caving.ab.ca/cadomin_cave.htm |date=2009-04-18 }}</ref>

==Stratigraphy==
The Cadomin [[geological formation|Formation]] is of [[Early Cretaceous]] ([[Barremian]] to [[Aptian]]) [[Geochronology|age]]. It is the basal unit of the [[Bullhead Group]] in northeastern [[British Columbia]] and of the [[Blairmore Group]] in Alberta.<ref name=Mossop19 /> The formation is a distinctive [[marker horizon]], and it was sometimes called the "coal conglomerate" because it was useful as a reference point for locating the coal seams of the underlying [[Mist Mountain Formation]] and the overlying [[Gething Formation]].<ref name=McLean>McLean, J.R. 1977. The Cadomin Formation: Stratigraphy, sedimentology, and tectonic implications. Bulletin of Canadian Petroleum Geology 25: 792-827.</ref> It is not fossiliferous.

==Lithology==
[[File:Cadomin FM micro.JPG|thumb|left|A [[photomicrography|photomicrograph]] of Cadomin Formation sandstone.]]
[[File:Cadomin Formation outcrops along Mt Allan Centenial Ridge Trail.jpg|thumb|left|Rounded [[pebble]]s and [[cobble (geology)|cobbles]] in the Cadomin Formation, Centennial Ridge Trail, Mount Allan, Alberta.]]
The formation consists primarily of [[conglomerate (geology)|conglomerate]], although at some localities there are minor interbeds of coarse-grained [[sandstone]], [[shale]], and [[coal]]. The conglomerate is typically massive and consists of well-rounded pebbles, [[cobble (geology)|cobbles]] and [[boulder]]s of white, grey and green [[chert]], and white and grey [[quartzite]], in a matrix of quartzose sand. In some areas there are also minor pebbles, cobbles and boulders of [[limestone]], [[Dolomite (rock)|dolomite]], black [[argillite]] and, rarely, greenish [[volcanic rock|volcanics]]. The conglomerate and sandstone beds are cemented with [[silica]], making them very hard and resistant to erosion, so they tend to form prominent [[outcrop]]s.<ref name=Stott>Stott, D.F. 1965. Lower Cretaceous Bullhead and Fort St John Groups, between Smoky and Peace Rivers, Rocky Mountain foothills, Alberta and British Columbia. Geological Survey of Canada, Bulletin 152, 279 p. {{ISBN|0-660-10208-0}}.</ref>

==Environment of deposition==
Deposition of the Cadomin Formation marked the renewal of subsidence and sedimentation following a long period of uplift, exposure and erosion of older strata.<ref name=Mossop19 /> The Cadomin sediments were derived from sources in the mountains to the west, and were deposited across the [[pediment (geology)|pediment]] surface by systems of [[alluvial fan]]s and [[braided river|braided streams]]. It is postulated that the streams flowed generally northeastward, turning northwestward at the Fox Creek Escarpment.<ref name="McLean" />

==Paleontology==
The Cadomin Formation preserves the oldest dinosaur skeletal fossils from Alberta (and anywhere west of Nova Scotia in Canada).<ref>Nagesan, R.S. et al. 2019</ref> The fossil material is attributable to a polacanthid ankylosaur, and comes from the basal unit of the Cadomin formation known as the Pocaterra Creek member. Unattributed turtle material was also reported from the formation, and the same locality as the dinosaur material.<ref name="Nagesan, R.S. et al.">Nagesan, R.S., Campbell, J.A., Pardo, J.D., Lennie, K.I., Vavrek, M.J., & Anderson, J.S. (2019). An Early Cretaceous (Berriasian) fossil-bearing locality from the Rocky Mountains of Alberta, yielding the oldest dinosaur skeletal remains from western Canada. Canadian Journal of Earth Sciences. [Just-in Article, December 19th 2019]. 10.1139/cjes-2019-0166</ref>

==Distribution==
[[Outcrop]]s near [[Cadomin, Alberta]] are the [[type locality (geology)|type locality]]. The formation is exposed at the surface in the foothills of the [[Canadian Rockies]], extending from the [[Canada–United States border|Canada–US border]] in southeastern British Columbia and southwestern Alberta and to the [[Peace River (Canada)|Peace River]] region in northeastern British Columbia, a distance of more than {{convert|1000|km|mi|sp=us}}. It is also recognizable in the subsurface east of the foothills. It ranges in thickness from {{convert|1|m|ft}} to more than {{convert|170|m|ft}} and is generally thicker and more coarse grained in the west.<ref name=Glass>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}}.</ref>

==Relationship to other units==
The Cadomin Formation overlies a major regional [[unconformity]] caused by pre-Cadomin erosion, although little or no evidence of the angular nature of that unconformity is apparent at most outcrops.<ref name="Stott" /> It rests unconformably on the [[Fernie Formation]], the [[Nikanassin Formation]], the [[Minnes Group]] or the [[Kootenay Group]], depending on the location and the extent of the erosion. It is conformably overlain by the [[Gladstone Formation]] in Alberta and [[Gething Formation]] in northeastern British Columbia, and it is equivalent to the base of the [[Mannville Group]].<ref name=Mossop19>{{Cite web|url=http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm|title=The Geological Atlas of the Western Canada Sedimentary Basin, Chapter 19: Cretaceous Mannville Group of the Western Canada Sedimentary Basin|author=Mossop, G.D. and Shetsen, I. (compilers), Canadian Society of Petroleum Geologists and Alberta Geological Survey|year=1994|accessdate=2016-06-20|archive-url=https://web.archive.org/web/20160701131122/http://ags.aer.ca/reports/atlas-of-the-western-canada-sedimentary-basin.htm|archive-date=2016-07-01|url-status=dead}}</ref>

==Hydrocarbon production==
[[Natural gas]] is produced from the Cadomin Formation in the Deep Basin area of western Alberta in the [[Hinton, Alberta|Hinton]]-[[Grande Cache]]-[[Grande Prairie]] area, and in the Cutbank area in northeastern British Columbia.<ref>Varley, C.J. 1984. The Cadomin Formation: A model for the Deep Basin type gas trapping mechanism. In: Stott, D.F. and Glass, D.J. (editors), Mesozoic of Middle North America; Canadian Society of Petroleum Geologists, Memoir 9, p. 471-484.</ref>

==Gallery==
<gallery>

File:Elbow Falls.JPG|[[Elbow Falls]] flows over a Cadomin Formation outcrop.
File:Cadomin_Formation.jpg|Cadomin Formation outcrops along the Centennial Ridge Trail, [[Mount Allan (Canada)|Mount Allan]], Alberta.
</gallery>

==References==
{{reflist}}

{{Western Canadian Sedimentary Basin|Canadian Rockies=yes|Northwest_Plains=yes}}

[[Category:Geologic formations of Alberta]]
[[Category:Cretaceous Alberta]]
[[Category:Barremian Stage]]
[[Category:Aptian Stage]]
[[Category:Conglomerate formations of Canada]]
[[Category:Sandstone formations of Canada]]
[[Category:Shale formations of Canada]]
[[Category:Coal formations]]
[[Category:Geologic formations of British Columbia]]

Cadomin Formation - Revision history

imported>Volcanoguy: removed Category:Conglomerate formations; added Category:Conglomerate formations of Canada using HotCat