The Beaverhill Lake Group is a geologic unit of

Middle Devonian In the geological timescale, the Middle Devonian epoch (from 393.3 ± 1.2 million years ago to 382.7 ± 1.6 million years ago) occurred during the Devonian period, after the end of the Emsian age. The Middle Devonian epoch is subdivided into two ...

Late Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era during the Phanerozoic eon, spanning 60.3 million years from the end of the preceding Silurian period at million years ago ( Ma), to the beginning of the succeeding ...

(late

Givetian The Givetian is one of two faunal stages in the Middle Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Eifelian Stage and followed by the Frasnian Stage. It is named after the town of Givet in ...

Frasnian The Frasnian is one of two faunal stages in the Late Devonian Period. It lasted from million years ago to million years ago. It was preceded by the Givetian Stage and followed by the Famennian Stage. Major reef-building was under way during ...

)

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone has been alive or something has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

in the

Western Canada Sedimentary Basin The Western Canada Sedimentary Basin (WCSB) underlies of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. This vast sedimentary ba ...

that is present in the southwestern

Northwest Territories The Northwest Territories is a federal Provinces and territories of Canada, territory of Canada. At a land area of approximately and a 2021 census population of 41,070, it is the second-largest and the most populous of Provinces and territorie ...

, northeastern

British Columbia British Columbia is the westernmost Provinces and territories of Canada, province of Canada. Situated in the Pacific Northwest between the Pacific Ocean and the Rocky Mountains, the province has a diverse geography, with rugged landscapes that ...

and

Alberta Alberta is a Provinces and territories of Canada, province in Canada. It is a part of Western Canada and is one of the three Canadian Prairies, prairie provinces. Alberta is bordered by British Columbia to its west, Saskatchewan to its east, t ...

. It was named by the geological staff of

Imperial Oil Imperial Oil Limited () is a Canadian petroleum company. It is Canada's second-largest integrated oil company. It is majority-owned by American oil company ExxonMobil, with a 69.6% ownership stake in the company. It is a producer of crude oil, ...

in 1950 for

Beaverhill Lake Beaverhill Lake () is a large lake in central Alberta, Canada. It is a site of regional importance in the Western Hemisphere Shorebird Reserve Network. It is managed by the Canadian Wildlife Service division of Environment Canada. It is located 7 ...

, Alberta, based on the

core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (laboratory), a highly specialized shared research resource * Core (manufacturing), used in casting and molding * Core (optical fiber ...

from a

well A well is an excavation or structure created on the earth by digging, driving, or drilling to access liquid resources, usually water. The oldest and most common kind of well is a water well, to access groundwater in underground aquifers. The ...

that they had drilled southeast of the lake, near Ryley, Alberta (Anglo-Canadian Beaverhill Lake No. 2, 11-11-50-17W4).

Petroleum Petroleum, also known as crude oil or simply oil, is a naturally occurring, yellowish-black liquid chemical mixture found in geological formations, consisting mainly of hydrocarbons. The term ''petroleum'' refers both to naturally occurring un ...

is produced from the Swan Hills Formation of the Beaverhill Lake Group in the

Swan Hills Swan Hills is a town in northern Alberta, Canada. It is in the eponymous Swan Hills (Alberta), Swan Hills, approximately north of Whitecourt and northwest of Fort Assiniboine. The town is at the junction of Alberta Highway 32, Highway 32 and Alb ...

area of

northern Alberta Northern Alberta is a geographic region located in the Canadian province of Alberta. An informally defined cultural region, the boundaries of Northern Alberta are not fixed. Under some schemes, the region encompasses everything north of the ce ...

Lithology

The Beaverhill Lake Group consists of

anhydrite Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO4. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the ...

and

carbonate rock Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals. The two major types are limestone, which is composed of calcite or aragonite (different crystal forms of CaCO3), and Dolomite (rock), dolomite rock (also kn ...

s at the base (the Fort Vermillion Formation), overlain by interbedded sequences of

calcareous Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime (mineral), lime or being chalky. The term is used in a wide variety of Science, scientific disciplines. In zoology ''Calcare ...

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of Clay mineral, clay minerals (hydrous aluminium phyllosilicates, e.g., Kaolinite, kaolin, aluminium, Al2Silicon, Si2Oxygen, O5(hydroxide, OH)4) and tiny f ...

argillaceous Clay minerals are hydrous aluminium phyllosilicates (e.g. kaolin, Al2 Si2 O5( OH)4), sometimes with variable amounts of iron, magnesium, alkali metals, alkaline earths, and other cations found on or near some planetary surfaces. Clay mineral ...

micritic

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

and dolomite. The group becomes thicker and more shaly to the west.

Distribution and thickness

The Beaverhill Lake Group is present beneath the plains of the southwestern Northwest Territories, northeastern British Columbia and Alberta. It reaches a maximum thickness of about in

central Alberta Central Alberta is a region located in the Canadian province of Alberta. Central Alberta is the most densely populated rural area in the province. Agriculture and energy are important to the area's economy. Geography Central Alberta is bordered ...

Outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth and other terrestrial planets. Features Outcrops do not cover the majority of the Earth's land surface because in most p ...

s of one of its formations (the Waterways) can be seen along the Athabasca and Clearwater Rivers in the

Fort McMurray Fort McMurray ( ) is an urban service area in the Regional Municipality of Wood Buffalo in Alberta, Canada. It is located in northeast Alberta, in the middle of the Athabasca oil sands, surrounded by boreal forest. It has played a significa ...

area.Norris, A.W. 1963. Devonian stratigraphy of northeastern Alberta and northwestern Saskatchewan. Geological Survey of Canada, Memoir 313.

Stratigraphy

;

Central Alberta Central Alberta is a region located in the Canadian province of Alberta. Central Alberta is the most densely populated rural area in the province. Agriculture and energy are important to the area's economy. Geography Central Alberta is bordered ...

;

area In

and northeastern

the unit has

formation Formation may refer to: Linguistics * Back-formation, the process of creating a new lexeme by removing or affixes * Word formation, the creation of a new word by adding affixes Mathematics and science * Cave formation or speleothem, a secondary ...

status and is not subdivided.

Environment of deposition

The formations of the Beaverhill Lake Group were deposited in an

embayment A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a ''gulf'', ''sea'', ''sound'', or ''bight''. A ''cove'' is a small, ci ...

that extended from an open

ocean The ocean is the body of salt water that covers approximately 70.8% of Earth. The ocean is conventionally divided into large bodies of water, which are also referred to as ''oceans'' (the Pacific, Atlantic, Indian Ocean, Indian, Southern Ocean ...

in the present-day

in Canada, to

North Dakota North Dakota ( ) is a U.S. state in the Upper Midwest, named after the indigenous Dakota people, Dakota and Sioux peoples. It is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minneso ...

in the United States. An extensive reef complex called the Presqu'ile Barrier had developed across the mouth of the embayment, blocking it from the open ocean and restricting the inflow of sea water. Low water levels and excessive

evaporation Evaporation is a type of vaporization that occurs on the Interface (chemistry), surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evapora ...

led to the deposition of the anhydrite-rich Fort Vermillion Formation at the base of the group in northern areas. Water levels then increased throughout the embayment, and the overlying

s were deposited in reefs (Swan Hills Formation), and in

carbonate platform A carbonate platform is a Sedimentary rock, sedimentary body which possesses topographic relief, and is composed of Autochthon (geology), autochthonic calcareous deposits. Platform growth is mediated by Sessility (zoology), sessile organisms whose ...

and basin environments (Waterways Formation).Wendte, J. and Uyeno, T. 2005. Sequence stratigraphy and evolution of Middle to Upper Devonian Beaverhill Lake strata, south-central Alberta. Bulletin of Canadian Petroleum Geology. v. 53, no. 3, p. 250-354.

Relationship to other units

The Beaverhill Lake Group is conformably underlain by the formations of the

Elk Point Group The Elk Point Group is a stratigraphic unit of Early to Middle Devonian age in the Western Canada and Williston sedimentary basins. It underlies a large area that extends from the southern boundary of the Northwest Territories in Canada to Nort ...

. In most areas it is conformably overlain by the formations of the Woodbend Group, and in northwestern Alberta and northeastern British Columbia it is disconformably overlain by the

Muskwa Formation The Muskwa Formation is a stratigraphic unit of Frasnian age in the Western Canadian Sedimentary Basin. It takes the name from Muskwa River, and was first described in the Western National Gas Fort Nelson a-95-J/94-J-10 well by F.F. Gray and J.R ...

. It is equivalent to the Souris River Formation in southeastern Alberta,

Saskatchewan Saskatchewan is a Provinces and territories of Canada, province in Western Canada. It is bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and to the south by the ...

and

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

, and to the Flume Formation of the Fairholme Group in the

Canadian Rockies The Canadian Rockies () or Canadian Rocky Mountains, comprising both the Alberta Rockies and the British Columbian Rockies, is the Canadian segment of the North American Rocky Mountains. It is the easternmost part of the Canadian Cordillera, w ...

. According to D.L Griffin, it is equivalent to the

Slave Point Formation The Slave Point Formation is a stratigraphic unit of Middle Devonian age in the Western Canadian Sedimentary Basin. It takes the name from Slave Point, a promontory on the north-west shore of the Great Slave Lake, and was first described in outc ...

and

Waterways Formation The Beaverhill Lake Group is a geologic unit of Middle Devonian to Late Devonian (late Givetian to Frasnian) age in the Western Canada Sedimentary Basin that is present in the southwestern Northwest Territories, northeastern British Columbia an ...

in northeastern Alberta, with the

and the lower

Hay River Formation The Hay River Formation is a geologic formation in Northwest Territories. It preserves fossils dating back to the Devonian period. See also * List of fossiliferous stratigraphic units in Northwest Territories This is a list of fossiliferous ...

in the

District of Mackenzie The District of Mackenzie was a regional administrative district of Canada's Northwest Territories. The district consisted of the portion of the Northwest Territories directly north of British Columbia, Alberta, and Saskatchewan on Canada's main ...

, as well as the

Horn River Formation The Horn River Formation (also ''Horn River Shale'') is a stratigraphic unit of Devonian (early Givetian to late Frasnian) age in the Western Canadian Sedimentary Basin. It is a thick sequence of marine sediments that was first described in outc ...

and Fort Simpson Formation northwest of the Slave Point- Keg River facies in northeastern British Columbia and the

.Griffin, D.L., 1965. "The facies front of the Devonian Slave Point - Elk Point sequence in northeastern British Columbia and the Northwest Territories"; Journal of Canadian Petroleum Technology, vol. 4, no. 1, pp. 13-22.

Paleontology

The carbonate rocks of the Beaverhill Lake Group contain rich

brachiopod Brachiopods (), phylum (biology), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear e ...

faunas.Norris, A.W. 1983. Brachiopods (''Schizophoria, Strophodonta'' (''Strophodonta''), ''Nervostrophia, Eostrophalosia'' and ''Devonoproductus'') from the lower Upper Devonian Waterways Formation of northeastern Alberta. Geological Survey of Canada, Bulletin 350. There are also

crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...

ostracod Ostracods, or ostracodes, are a Class (biology), class of the crustacean, Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 33,000 species (only 13,000 of which are extant taxon, extant) have been identified,Brandão, S.N.; Antoni ...

s and

coral Corals are colonial marine invertebrates within the subphylum Anthozoa of the phylum Cnidaria. They typically form compact Colony (biology), colonies of many identical individual polyp (zoology), polyps. Coral species include the important Coral ...

s, and, in the Swan Hills Formation, stromatoporoids.

Hydrocarbon production

Since 1957

oil An oil is any nonpolar chemical substance that is composed primarily of hydrocarbons and is hydrophobic (does not mix with water) and lipophilic (mixes with other oils). Oils are usually flammable and surface active. Most oils are unsaturate ...

has been produced from the Swan Hills Formation of the Beaverhill Lake Group in the

area of

, where it includes Devonian

reef A reef is a ridge or shoal of rock, coral, or similar relatively stable material lying beneath the surface of a natural body of water. Many reefs result from natural, abiotic component, abiotic (non-living) processes such as deposition (geol ...

structures similar to those of the

Leduc Formation The Leduc Formation is a stratigraphic unit of Late Devonian (Frasnian) age in the Western Canada Sedimentary Basin. It takes its name from the city of Leduc, and it was formally described from the B.A. Pyrz No. 1 well in central Alberta, between ...

and the Rainbow Member in Alberta.Barss, D.L., Copland, A.B., and Ritchie, W.D., 1970, Middle Devonian Reefs, Rainbow Area, Alberta, in Geology of Giant Petroleum Fields, AAPG Memoir 14, Halbouty, M.T., editor, Tulsa: American Association of Petroleum Geologists, pp. 18-49Hemphill, C.R., Smith, R.I., and Szabo, F., 1970, Geology of Beaverhill Lake Reefs, Swan Hills Area, Alberta, in Geology of Giant Petroleum Fields, AAPG Memoir 14, Halbouty, M.T., editor, Tulsa: American Association of Petroleum Geologists, pp. 50-90

References

{{Western Canadian Sedimentary Basin, Northeast_Plains=yes, Northwest_Plains=yes, South AB=yes Western Canadian Sedimentary Basin Geologic groups of Alberta Geologic groups of British Columbia Geologic groups of the Northwest Territories Devonian southern paleotropical deposits Middle Devonian Series Upper Devonian Series Devonian Alberta Devonian British Columbia Devonian Northwest Territories Shale groups of Canada Limestone groups of Canada Dolomite groups