{{Short description|Geological formation}} {{Infobox Rockunit | name = Doig Formation | image = | caption = | type = Geological formation | age = middle Anisian-Ladinian<br>~{{Fossil range|245|237}} | period = Middle Triassic | prilithology = Siltstone, shale | otherlithology = Phosphate, sandstone | namedfor = Doig River | namedby = J.H. Armitage | year_ts = 1962 | region = NW Alberta<br>NE British Columbia<br>SE Yukon | country = Canada | coordinates = {{coord|55.7|N|121.3|W|display=inline,title}} | paleocoordinates = {{coord|25.1|N|35.0|E|display=inline}} | unitof = | subunits = | underlies = Halfway Formation | overlies = Montney Formation | thickness = up to {{convert|190|m|ft|-1}}<ref name=lexicon/> | extent = Western Canadian Sedimentary Basin | area = | map = {{Location map+ | Canada#British Columbia | relief = 1 | width = 250 | float = center | places = {{Location map~ | Canada#British Columbia | lat_deg = 55.7 | lon_deg = -121.3 | mark = Pink ff0080 pog.svg | marksize = 12 }} }} | map_caption = }}
The '''Doig Formation''' is a geologic formation of middle Triassic age in the Western Canadian Sedimentary Basin. It takes the name from Doig River, a tributary of the Beatton River, and was first described in the Texaco N.F.A. Buick Creek No. 7 well (located north-west of Fort St. John, east of the Alaska Highway) by J.H. Armitage in 1962. .<ref>Armitage, J.H., 1962. Triassic oil and gas occurrences in northeastern British Columbia, Canada. J. Alberta Society of Petroleum Geologists, v. 10, p. 35-36.</ref>
== Lithology == The Doig Formation is composed of fine grained, grey argillaceous siltstone and dark calcareous shale. <ref name=lexicon> {{Cite web |url = http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:004083 |title = Doig Formation |author = Lexicon of Canadian Geologic Units |accessdate = 2009-03-21 |url-status = dead |archiveurl = https://archive.today/20130221084810/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:004083 |archivedate = 2013-02-21 }} </ref> Phosphate nodules occur at the base of the formation. Anomalously thicker, porous sandstone channels and bars are present locally in the upper units of the formation.<ref>{{cite book |editor-last=Glass |editor-first=D. J. |title=Lexicon of Canadian Stratigraphy: Western Canada Including Eastern British Columbia, Alberta, Saskatchewan and Southern Manitoba |volume=4 |publisher=Canadian Society of Petroleum Geologists |location=Calgary, Alberta |year=1990 |pages=772 |isbn=0-920230-23-7 }}</ref> The formation has provided fossils of various species of conodonts; ''Magnigondolella alexanderi'', ''M. cyri'', ''M. julii'', ''M. nebuchadnezzari'', ''M. salomae'', ''Neogondolella curva'', ''N. hastata'', ''N. panlaurentia'' and ''N. ex gr. shoshonensis''.<ref name=Golding2018>{{cite journal |last1=Golding |first1=M. L. |first2=M. J. |last2=Orchard |year=2018 |title=''Magnigondolella'', a new conodont genus from the Triassic of North America |journal=Journal of Paleontology |volume=92 |issue=2 |pages=207–220|doi=10.1017/jpa.2017.123 |bibcode=2018JPal...92..207G |s2cid=133681181 }}</ref>
== Distribution == The Doig Formation reaches a maximum thickness of {{convert|190|m|ft|-1}} in the Canadian Rockies foothills it thins towards the north and east. It occurs in the subsurface in north-western Alberta, north-eastern British Columbia and southern Yukon, from 53°N and 118°W to the Canadian Rockies.<ref name=lexicon/>
== Relationship to other units == The Doig Formation is unconformably overlain by the Halfway Formation of the Schooler Creek Group; the contact is marked by a dolomitic bed and a chert and quartz conglomerate bed.<ref>{{Cite web|url=http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:006138 |archive-url=https://archive.today/20120715034615/http://cgkn1.cgkn.net/weblex/weblex_litho_detail_e.pl?00053:006138 |url-status=dead |archive-date=2012-07-15 |title=Halfway Formation |author=Lexicon of Canadian Geologic Units |accessdate=2009-03-21 }}</ref> To the west it is overlain by younger Jurassic beds. It conformably overlies the Montney Formation and the contact is marked by a phosphate pellet bed in the base of the Doig.<ref name=lexicon/>
The formation correlates with the lower Llama Member of the Sulphur Mountain Formation in the southern ranges of the Canadian Rockies, with the Whistler Member of the Whitehorse Formation in the Muskwa Ranges, and with the Toad Formation in the upper Liard River area.<ref name=lexicon/>
== Petroleum geology == The Doig formation is an important source rock for the Triassic Halfway and Charlie Lake formations.<ref>{{cite journal|last1=Riediger|first1=C.L.|title=Lower and Middle Triassic source rocks, thermal maturation, and oil-source rock correlations in the Peace River Embayment area, Alberta and British Columbia|journal=Bulletin of Canadian Petroleum Geology|date=December 1990|volume=38 A|pages=218–235|url=http://archives.datapages.com/data/cspg/data/038a/038a001/0218.htm}}</ref> Total organic carbon values in the "phosphate zone" at the base of the Doig are commonly greater than 4% by weight and can reach up to 11%. The "phosphate zone" is also a potential undeveloped shale gas reservoir with as much as 400 trillion cubic feet of natural gas in place.<ref>{{cite journal|last1=Walsh|first1=Warren|title=Regional "Shale Gas" Potential of the Triassic Doig and Montney Formations Northeastern British Columbia|journal=British Columbia Geoscience Petroleum Geology Open File 2006-02|date=2006|url=http://www2.gov.bc.ca/gov/DownloadAsset?assetId=789339983AF04FA8A5E26162448B41F0}}</ref> Oil and gas is also extracted from the Doig Formation in conventional reservoirs along the western Montney trend and in the Peace River Arch.
== References == {{reflist}}
{{Western Canadian Sedimentary Basin|Northwest_Plains=yes}}
Category:Triassic System of North America Category:Triassic Alberta Category:Triassic British Columbia Category:Triassic Yukon Category:Anisian Stage Category:Ladinian Stage Category:Siltstone formations of the United States Category:Shale formations of Canada Category:Source rock formations Category:Reservoir rock formations Category:Geologic formations of Alberta Category:Geologic formations of British Columbia Category:Geologic formations of Yukon