Elk Point Group
Stratigraphic range: Early to MiddleDevonian PreꞒ Ꞓ O S D C P T J K Pg N
Blue halite (Prairie Evaporite Formation, upper Elk Point Group, MiddleDevonian) fromSaskatchewan
Type	Geological formation
Sub-units	Upper and Lower Elk Point Group
Underlies	Beaverhill Lake Group,Manitoba Group
Overlies	Precambrian toSilurianformations[1]
Thickness	up to 610 metres (2,000 ft)[2]
Lithology
Primary	dolomite,halite,anhydrite
Other	Limestone,shale,potash
Location
Coordinates	53°54′19″N110°37′49″W / 53.9053°N 110.6304°W /53.9053; -110.6304 (Elk Point Group)
Region	Northernplains
Country	Canada United States
Type section
Named for	Elk Point
Named by	J.R. McGehee[3]

TheElk Point Group is astratigraphic unit ofEarly toMiddle Devonianage in theWestern Canada andWillistonsedimentary basins. It underlies a large area that extends from the southern boundary of theNorthwest Territories inCanada toNorth Dakota in theUnited States. It has been subdivided into numerousformations,^[4] number of which host majorpetroleum andnatural gasreservoirs.^[5]

The formations of the Elk Point Group are composed primarily ofcarbonate rocks (dolomite andlimestone) andevaporitic rocks (halite,anhydrite andpotash), with lesser amounts ofdolomiticmudstone andshale.^[2]

Some of the carbonate formations of the Elk Point Group contain rich assemblages of marineinvertebratefossils, including many species ofbrachiopods,gastropods,bivalves,cephalopods,crinoids,ostracods andcorals. The evaporitic formations are unfossiliferous or contain a fewspores andalgal remains.^[2]

The formations of the Elk Point Group were deposited in a marineembayment that stretched from an openocean in the present-dayNorthwest Territories of Canada to North Dakota in the United States, covering an area roughly half as large as that covered by today'sMediterranean Sea. At times of low water levels and excessiveevaporation, halite and otherevaporite minerals were deposited insabkha,supratidal flat and coastallagoon environments, and at times of higher water levelscarbonate platform sedimentation andreef growth were dominant.^[1][4]

The Elk Point Group extends from the southern boundary of theNorthwest Territories through northwesternBritish Columbia,Alberta,Saskatchewan, and southwesternManitoba in Canada, and continues into easternMontana andNorth Dakota in the United States.^[1] It reaches a maximum thickness of about 610 metres (2,000 ft) in eastern Alberta.^[2]

The Elk Point Group was named for the town ofElk Point, Alberta by J.R. McGehee in 1949.^[3]Core from awell that was drilled near Elk Point has been designated as thetype section (Anglo-Canadian Elk Point No. 11, 2-11-57-5W4).^[1] The group is subdivided into the Lower and Upper Elk Point Group, each of which is further subdivided into formations according to the dominantlithologies,^[1][2] as shown in the tables below.

The Lower Elk Point Group comprises all strata lying below theWinnipegosis Formation (in the south) or theKeg River Formation (in the north) and is present only in the deepest parts of thebasin. The Upper Elk Point Group, which is present throughout the basin, includes those formations and all overlying formations to the base of theManitoba Group (in the south) or theBeaverhill Lake Group (in the north).^[1]

Innorthern Alberta andcentral Alberta, the Elk Point Group contains the following subdivisions, from top to base:

Insouthern Alberta

The Elk Point Group is dolomitic and is not differentiated.

InSaskatchewan,Manitoba andMontana

The Elk Point Group is conformably overlain by theManitoba Group in Manitoba and Saskatchewan, and by theBeaverhill Lake Group in Alberta. It restsunconformably onPrecambrianbasement rocks in northern Alberta, onCambrian strata in northeastern Alberta and in Saskatchewan, and onOrdovician toSilurian^[1] formations in western Alberta, Saskatchewan and southwestern Manitoba.^[2] In the Northwest Territories, some of its uppermost units are exposed at surface or are unconformably overlain by Cretaceous strata.^[1]

The Lower Elk Point Group is equivalent to theStone Formation and its equivalents, and theHeadless andNahanni Formations, in northeastern British Columbia and the southwestern Northwest Territories. In the same areas, the Upper Elk Point includes thePine Point Group, and is equivalent to parts of theHorn River Formation,Besa River Formation, and others.^[2]

The porous carbonate rocks of the Elk Point Group host majorpetroleum andnatural gasreservoirs. As of 1994, the Initial Established Recoverable Petroleum Reserves and the Cumulative Petroleum Production for the group were estimated at 339.3 and 240.4 million cubic metres, respectively. For natural gas, the Initial Established Marketable Reserves and the Cumulative Production were estimated at 142.7 and 79.5 billion cubic metres, respectively.^[5]

• Geologic groups of the United States
• Oil-bearing shales in Canada
• Oil-bearing shales in the United States
• Western Canadian Sedimentary Basin
• Devonian Alberta
• Devonian British Columbia
• Devonian Montana
• Devonian North Dakota
• Devonian Northwest Territories
• Devonian Saskatchewan
• Geologic groups of Montana
• Geologic groups of North Dakota
• Geologic groups of Alberta
• Geologic groups of British Columbia
• Geologic groups of Saskatchewan
• Devonian System of North America
• Devonian southern paleotropical deposits
• Lower Devonian Series
• Middle Devonian Series
• Devonian southern paleotemperate deposits
• Geologic groups of the Northwest Territories

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