imported>Onel5969: Disambiguating links to Ichthyosaur (link changed to Ichthyosauria) using DisamAssist.

2025-07-01T09:06:52Z

Disambiguating links to Ichthyosaur (link changed to Ichthyosauria) using DisamAssist.

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{{short description|Stratigraphic unit in Canada}}
{{Infobox Rockunit
| name = Clearwater Formation
| image =
| caption =
| type = [[Geological formation]]
| age = {{fossil range|Albian|Albian|[[Albian]]}}
| period = Albian
| prilithology = [[Shale]]
| otherlithology = [[Sandstone]], [[siltstone]]
| namedfor = [[Clearwater River (Saskatchewan)|Clearwater River]]
| namedby = R.G. McConnell, 1893
| region = northeastern and central [[Alberta]]
| country = [[Canada]]
| coordinates = {{coord|58.01365|N|111.34377|W|region:CA-AB|name=Clearwater Formation}}
| unitof = [[Mannville Group]]
| subunits = [[Wabiskaw Member]]
| underlies = [[Grand Rapids Formation]]
| overlies = [[McMurray Formation]]
| thickness = up to {{convert|85|m|ft|-1}}<ref name=Glass />
| extent =
| area =
| map =
| map_caption =
}}
The '''Clearwater Formation''' is a [[stratigraphic unit]] of [[Early Cretaceous]] ([[Albian]]) [[Geochronology|age]] in the [[Western Canadian Sedimentary Basin|Western Canada Sedimentary Basin]] in northeastern [[Alberta]], Canada.<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> It was first defined by R.G. McConnell in 1893 and takes its name from the [[Clearwater River (Saskatchewan)|Clearwater River]] near [[Fort McMurray]].<ref>McConnell, R.G., 1893. Report on a portion of the district of Athabasca, comprising the country between Peace River and Athabasca River north of Lesser Slave Lake. [[Geological Survey of Canada]], Annual Report (new series), 1890-91, v. 5, Part 1, p. 1-67.</ref>

Impermeable marine [[shale]]s in the Clearwater Formation provided part of the [[petroleum reservoir|trapping mechanism]] for the underlying [[Athabasca oil sands]] in the [[McMurray Formation]]. [[Sandstone]] units in the Clearwater Formation, including the Wabiskaw Member, can contain [[oilsand]] and [[Petroleum|heavy oil]] resources.<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>

Nearly complete specimens of [[plesiosaur]]s and [[Ichthyosauria|ichthyosaur]]s, as well as one [[Ankylosauria|ankylosaur]], have been recovered from the formation during oilsand mining.<ref name=Henderson2>{{Cite web|url=https://www.theguardian.com/science/lost-worlds/2013/may/13/dinosaurs-fossils
|title= A one-in-a-billion dinosaur find|work=The Guardian|author= Henderson, D.|year=2013|accessdate=2013-11-21}}</ref>

==Lithology==
The Clearwater Formation consists of primarily of black and green shale, with some interbedded grey and green sandstone and siltstone, and [[ironstone]] [[concretion]]s. To the southeast of [[Cold Lake (Alberta)|Cold Lake]] it includes massive hydrocarbon-bearing, [[glauconite|glauconitic]] salt-and-pepper sandstones with interbedded shales.<ref name="Glass" />

===Wabiskaw Member===
The Wabiskaw Member forms the base of the Clearwater Formation. It consists of glauconitic sandstones with interbeds of black fissile shale, and it includes oilsand and heavy oil in some areas.<ref name="Glass" /> It was defined in well ''Barnsdall West Wabiskaw No. 1'' (located between [[Wabasca River]] and [[Lesser Slave Lake]] in [[central Alberta]]) by P.C. Badgley in 1952.<ref>Badgley, Peter C., 1952. Notes on the subsurface stratigraphy and oil and gas geology of the Lower Cretaceous series in central Alberta (Report and seven figures); [[Geological Survey of Canada]], Paper No. 52-11, page 12</ref>

==Distribution==
The Clearwater Formation is present in the subsurface of northeastern and central Alberta, and is exposed on lower course of the [[Athabasca River]], as well as along the [[Christina River (Alberta)|Christina River]], a tributary of the [[Clearwater River (Saskatchewan)|Clearwater River]] southeast of [[Fort McMurray]]. It reaches a maximum thickness of {{convert|85|m|ft|-1}} on the Athabasca River, thins out to {{convert|6|m|ft|-1}} in the [[Cold Lake (Alberta)|Cold Lake]] area, and wedges out towards the south. It is not present south of [[Edmonton, Alberta|Edmonton]].<ref name="Glass" />

==Relationship to other units==
The Clearwater Formation is part of the [[Mannville Group]]. It is conformably overlain by the [[Grand Rapids Formation]] and conformably overlies the [[McMurray Formation]]. It is equivalent to the [[Bluesky Formation]] and the lower [[Spirit River Formation]] in the [[Peace River, Alberta|Peace River]] region, and may be equivalent to the [[Cummings Member]] in the [[Lloydminster]] region.<ref name="Glass" />

==Palaeontology==
[[File:Wapuskanectes specimen TMP2012.50.1 with gastroliths (cropped).png|thumb|219x219px|''[[Wapuskanectes]]'']]
The Clearwater Formation was deposited in marine, near-shore and estuarine environments on the eastern side of the [[Western Interior Seaway]], and it contains marine and, rarely, terrestrial fossils. Workers at mines near Fort McMurray have made a number of significant finds while removing Clearwater strata to expose underlying oilsand deposits. [[Plesiosaurs]] such as ''[[Nichollssaura]]'' and [[ichthyosaurs]] such as ''[[Athabascasaurus]]'', some of them nearly complete, have been recovered at [[Syncrude|Syncrude Canada Ltd.'s]] mines.<ref name="Henderson2" /><ref name="Syncrude">{{Cite web|url=http://www.syncrude.com/users/news_view.asp?FolderID=6835&NewsID=223|title=Another fossil unearthed at Syncrude's North Mine.|publisher=Syncrude Canada Ltd.|author=Syncrude Canada Ltd.|year=2012|accessdate=2013-11-21|archive-url=https://web.archive.org/web/20131203042029/http://www.syncrude.com/users/news_view.asp?FolderID=6835&NewsID=223|archive-date=2013-12-03|url-status=dead}}</ref>

The well-preserved holotype specimen of the nodosaurid ''[[Borealopelta]] markmitchelli'' has also been recovered at the [[Suncor]] Millennium Mine. Plesiosaurs and ichthyosaurs were large marine reptiles, but the ankylosaur was an armoured dinosaur and represents a terrestrial animal that became entombed in the sea floor approximately {{convert|200|km|mi|-1}} from the nearest known paleo-shoreline. Its bloated carcass probably washed out to sea and floated for several days before sinking to the sea floor.<ref name="Henderson2" />

All of the specimens now reside at the [[Royal Tyrrell Museum of Palaeontology]].<ref name="Henderson2" />

==Oil/gas production==
The formation contains oilsand in the [[Cold Lake (Alberta)|Cold Lake]] and [[Primrose Lake]] region. [[Petroleum|Heavy oil]] is produced from the loose sandstones of the Wabiskaw Member by means of [[horizontal drilling]] in the [[Wabasca oil field]], and the Wabiskaw contains [[open-pit mining|surface-mineable]] oilsand in the Fort McMurray area.

The oilsands of the Clearwater Formation are more difficult to tap than those of the McMurray Formation. [[Husky Energy|Cenovus]] Inc.'s Tucker thermal oilsands project which opened in 2006 began to post a modest return in 2013.<ref>{{cite web |title=Tucker oilsands project posts rare return |date=January 8, 2013 |url= http://blogs.calgaryherald.com/2013/01/08/tucker-oilsands-project-posts-rare-return |author=Calgary Herald}}</ref> [[Husky Energy|Cenovus]] Inc. (CVE), with its head office in Calgary, Alberta, Canada is an integrated oil and natural gas producer.

== Extraction ==
=== Cyclic Steam Stimulation (CSS) ===

[[Canadian Natural Resources]] use "employs cyclic steam or "huff and puff" technology to develop bitumen resources. This technology requires one well bore and the production consists of the injection and production phases. First steam is "injected for several weeks, mobilizing cold bitumen". Then the flow "on the injection well is reversed producing oil through the same injection well bore. The injection and production phases together comprise one cycle. "Steam is re-injected to begin a new cycle when oil production rates fall below a critical threshold due to the cooling of the reservoir."<ref name="CNRL">{{cite web|url=http://www.cnrl.com/operations/north-america/north-american-crude-oil-and-ngls/thermal-insitu-oilsands/|publisher=CNRL|year=2013|title=Cyclic Steam Stimulation|series=Thermal in situ oil sands|access-date=2013-07-30|archive-url=https://web.archive.org/web/20151016105950/http://www.cnrl.com/operations/north-america/north-american-crude-oil-and-ngls/thermal-insitu-oilsands/|archive-date=2015-10-16|url-status=dead}}</ref>

=== High pressure cyclic steam stimulation (HPCSS) ===

"Roughly 35 per cent of all ''in situ'' production in the Alberta [[oil sands]] uses a technique called High Pressure Cyclic Steam Stimulation (HPCSS), which cycles between two phases: first, steam is injected into an underground oilsands deposit to soften the bitumen; then, the resulting hot mixture of bitumen and steam (called a "bitumen emulsion") is pumped up to the surface. The process is then repeated multiple times."<ref name="SeversonBaker29Jul2013">{{cite web|title=Cold Lake bitumen blowout first test for new energy regulator|first=Chris |last=Severson-Baker|date=29 July 2013|url=http://www.pembina.org/blog/741}}</ref> An [[Alberta Energy Regulator]] (AER) news release explained the difference between high pressure cyclic steam stimulation (HPCSS) and steam assisted gravity drainage (SAGD). "HPCSS has been used in oil recovery in Alberta for more than 30 years. The method involves injecting high-pressure steam into a reservoir over a prolonged period of time. As heat softens the bitumen and water dilutes and separates the bitumen from the sand, the pressure creates cracks and openings through which the bitumen can flow back into the steam-injector wells. HPCSS differs from steam assisted gravity drainage (SAGD) operations where steam is injected at lower pressures without fracturing the reservoir and uses gravity drainage as the primary recovery mechanism."<ref name="AER18jul2013">{{cite news|url=http://www.aer.ca/about-aer/media-centre/news-releases/3632|title=Alberta Energy Regulator orders enhanced monitoring and further steaming restrictions at Primrose and Wolf Lake projects due to bitumen emulsion releases|date=18 July 2013|publisher=AER|access-date=30 July 2013|archive-url=https://web.archive.org/web/20130730233259/http://www.aer.ca/about-aer/media-centre/news-releases/3632|archive-date=30 July 2013|url-status=dead|ref={{sfnref|AER|2013}}}}</ref> [[Canadian Natural Resources|Canadian Natural Resources Limited's (CNRL)]] Primrose and Wolf Lake in situ oil sands project near [[CFB Cold Lake|Cold Lake, Alberta]] in the Clearwater Formation, operated by CNRL subsidiary [[Horizon Oil Sands]], use the high pressure cyclic steam stimulation (HPCSS).{{harv|AER|2013}}

==References==
{{reflist}}
{{Western Canadian Sedimentary Basin|Northeast_Plains=yes}}

[[Category:Geologic formations of Alberta]]
[[Category:Western Canadian Sedimentary Basin]]
[[Category:Albian Stage]]
[[Category:Cretaceous Alberta]]
[[Category:Shale formations of Canada]]
[[Category:Sandstone formations of Canada]]
[[Category:Siltstone formations of Canada]]

Clearwater Formation - Revision history

imported>Onel5969: Disambiguating links to Ichthyosaur (link changed to Ichthyosauria) using DisamAssist.