The Elk Point Group is a

stratigraphic Stratigraphy is a branch of geology concerned with the study of rock layers (strata) and layering (stratification). It is primarily used in the study of sedimentary and layered volcanic rocks. Stratigraphy has three related subfields: lithostrati ...

unit of

Early Early may refer to: History * The beginning or oldest part of a defined historical period, as opposed to middle or late periods, e.g.: ** Early Christianity ** Early modern Europe Places in the United States * Early, Iowa * Early, Texas * Early ...

Middle Devonian The Devonian ( ) is a geologic period and system of the Paleozoic era, spanning 60.3 million years from the end of the Silurian, million years ago (Mya), to the beginning of the Carboniferous, Mya. It is named after Devon, England, wher ...

age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or 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 Western Canada, also referred to as the Western provinces, Canadian West or the Western provinces of Canada, and commonly known within Canada as the West, is a Canadian region that includes the four western provinces just north of the Canada� ...

and Williston

sedimentary basin Sedimentary basins are region-scale depressions of the Earth's crust where subsidence has occurred and a thick sequence of sediments have accumulated to form a large three-dimensional body of sedimentary rock. They form when long-term subsidence ...

s. It underlies a large area that extends from the southern boundary of the

Northwest Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the Native Americans in the United States, indigenous Dakota people, Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north a ...

in the

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

. It has been subdivided into numerous formations, number of which host major

petroleum Petroleum, also known as crude oil, or simply oil, is a naturally occurring yellowish-black liquid mixture of mainly hydrocarbons, and is found in geological formations. The name ''petroleum'' covers both naturally occurring unprocessed crud ...

and

natural gas Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...

reservoirs A reservoir (; from French ''réservoir'' ) is an enlarged lake behind a dam. Such a dam may be either artificial, built to store fresh water or it may be a natural formation. Reservoirs can be created in a number of ways, including control ...

Lithology

The formations of the Elk Point Group are composed primarily of

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 (also known as dolosto ...

s (

dolomite Dolomite may refer to: *Dolomite (mineral), a carbonate mineral *Dolomite (rock), also known as dolostone, a sedimentary carbonate rock *Dolomite, Alabama, United States, an unincorporated community *Dolomite, California, United States, an unincor ...

and

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

) and evaporitic rocks (

halite Halite (), commonly known as rock salt, is a type of salt, the mineral (natural) form of sodium chloride ( Na Cl). Halite forms isometric crystals. The mineral is typically colorless or white, but may also be light blue, dark blue, purple, p ...

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

potash Potash () includes various mined and manufactured salts that contain potassium in water-soluble form.

), with lesser amounts of

dolomitic Dolomite () is an anhydrous carbonate mineral composed of calcium magnesium carbonate, ideally The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite. An alternative name sometimes used for the dolomiti ...

mudstone Mudstone, a type of mudrock, is a fine-grained sedimentary rock whose original constituents were clays or muds. Mudstone is distinguished from '' shale'' by its lack of fissility (parallel layering).Blatt, H., and R.J. Tracy, 1996, ''Petrology. ...

and

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

.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. .

Paleontology

Some of the carbonate formations of the Elk Point Group contain rich assemblages of marine

invertebrate Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordate ...

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

s, including many species of

brachiopod Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan 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 end, w ...

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

bivalve Bivalvia (), in previous centuries referred to as the Lamellibranchiata and Pelecypoda, is a class of marine and freshwater molluscs that have laterally compressed bodies enclosed by a shell consisting of two hinged parts. As a group, bival ...

cephalopod A cephalopod is any member of the molluscan class Cephalopoda (Greek plural , ; "head-feet") such as a squid, octopus, cuttlefish, or nautilus. These exclusively marine animals are characterized by bilateral body symmetry, a prominent head ...

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

ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

s and

coral Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and sec ...

s. The evaporitic formations are unfossiliferous or contain a few

spore In biology, a spore is a unit of sexual or asexual reproduction that may be adapted for dispersal and for survival, often for extended periods of time, in unfavourable conditions. Spores form part of the life cycles of many plants, algae, f ...

s and

algal Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

remains.

Environment of Deposition

The formations of the Elk Point Group were deposited in a marine

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, circular bay with a narr ...

that stretched from an open

ocean The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the wo ...

in the present-day

of Canada to North Dakota in the United States, covering an area roughly half as large as that covered by today's

Mediterranean Sea The Mediterranean Sea is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean Basin and almost completely enclosed by land: on the north by Western and Southern Europe and Anatolia, on the south by North Africa, and on the ea ...

. At times of low water levels and excessive

evaporation Evaporation is a type of vaporization that occurs on the surface of a liquid as it changes into the gas phase. High concentration of the evaporating substance in the surrounding gas significantly slows down evaporation, such as when humidi ...

, halite and other

evaporite An evaporite () is a water-soluble sedimentary mineral deposit that results from concentration and crystallization by evaporation from an aqueous solution. There are two types of evaporite deposits: marine, which can also be described as ocea ...

minerals were deposited in

sabkha A sabkha ( ar, سبخة) is a coastal, supratidal mudflat or sandflat in which evaporite-saline minerals accumulate as the result of semiarid to arid climate. Sabkhas are gradational between land and intertidal zone within restricted coastal p ...

, supratidal flat and coastal

lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...

environments, and at times of higher water levels

carbonate platform A carbonate platform is a sedimentary body which possesses topographic relief, and is composed of autochthonic calcareous deposits. Platform growth is mediated by sessile organisms whose skeletons build up the reef or by organisms (usually microb ...

sedimentation and

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 processes— deposition of sand, wave erosion planing down rock out ...

growth were dominant.

Distribution and Thickness

The Elk Point Group extends from the southern boundary of the

through northwestern

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

, and southwestern

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 o ...

in Canada, and continues into eastern

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

and

in the United States.Meijer Drees, N.C. 1986. Evaporitic deposits of western Canada. Geological Survey of Canada, paper 85-20. It reaches a maximum thickness of about in eastern Alberta.

Stratigraphy

The Elk Point Group was named for the town of

Elk Point, Alberta Elk Point is a town located in east-central Alberta, Canada. It is located on Highway 41. A number of oil related businesses have located in Elk Point. Agriculture is also important in the Elk Point area. Elk Point is located on the North Sas ...

by J.R. McGehee in 1949.McGehee, J.R., 1949. Pre-Waterways Paleozoic stratigraphy of Alberta Plains. Bull.

American Association of Petroleum Geologists The American Association of Petroleum Geologists (AAPG) is one of the world's largest professional geological societies with more than 40,000 members across 129 countries as of 2021. The AAPG works to "advance the science of geology, especially as ...

, 33:4, p. 603-613.

Core Core or cores may refer to: Science and technology * Core (anatomy), everything except the appendages * Core (manufacturing), used in casting and molding * Core (optical fiber), the signal-carrying portion of an optical fiber * Core, the central ...

from a

well A well is an excavation or structure created in the ground 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 was drilled near Elk Point has been designated as the

type section A stratotype or type section in geology is the physical location or outcrop of a particular reference exposure of a stratigraphic sequence or stratigraphic boundary. If the stratigraphic unit is layered, it is called a stratotype, whereas the stan ...

(Anglo-Canadian Elk Point No. 11, 2-11-57-5W4). The group is subdivided into the Lower and Upper Elk Point Group, each of which is further subdivided into formations according to the dominant

lithologies The lithology of a rock unit is a description of its physical characteristics visible at outcrop, in hand or core samples, or with low magnification microscopy. Physical characteristics include colour, texture, grain size, and composition. Lit ...

, as shown in the tables below. The Lower Elk Point Group comprises all strata lying below the Winnipegosis Formation (in the south) or the

Keg River Formation The Keg River Formation is a stratigraphic unit of Givetian age in the Western Canada Sedimentary Basin. Description It takes the name from the Keg River, a tributary of the Peace River, and was first described in the California Standard Steen ...

(in the north) and is present only in the deepest parts of the basin. The Upper Elk Point Group, which is present throughout the basin, includes those formations and all overlying formations to the base of the

Manitoba Group The Manitoba Group is a stratigraphical unit of middle to late Devonian age in the Western Canadian Sedimentary Basin. The group takes its name from the province of Manitoba, and was first defined by A.D. Baillie in 1953. Lithology The Manito ...

(in the south) or the

Beaverhill Lake Group 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 and A ...

(in the north).

Subdivisions

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 cent ...

and

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 bordere ...

, the Elk Point Group contains the following subdivisions, from top to base: ;In

southern Alberta Southern Alberta is a region located in the Canadian province of Alberta. In 2004, the region's population was approximately 272,017.Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

and

Relationship to Other Units

The Elk Point Group is conformably overlain by the

in Manitoba and Saskatchewan, and by the

in Alberta. It rests

unconformably An unconformity is a buried erosional or non-depositional surface separating two rock masses or strata of different ages, indicating that sediment deposition was not continuous. In general, the older layer was exposed to erosion for an interval o ...

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

basement rocks In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The baseme ...

in northern Alberta, on

Cambrian The Cambrian Period ( ; sometimes symbolized C with bar, Ꞓ) was the first geological period of the Paleozoic Era, and of the Phanerozoic Eon. The Cambrian lasted 53.4 million years from the end of the preceding Ediacaran Period 538.8 million ...

strata in northeastern Alberta and in Saskatchewan, and on

Ordovician The Ordovician ( ) is a geologic period and System (geology), system, the second of six periods of the Paleozoic Era (geology), Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start ...

Silurian The Silurian ( ) is a geologic period and system spanning 24.6 million years from the end of the Ordovician Period, at million years ago ( Mya), to the beginning of the Devonian Period, Mya. The Silurian is the shortest period of the Paleozo ...

formations in western Alberta, Saskatchewan and southwestern Manitoba. In the Northwest Territories, some of its uppermost units are exposed at surface or are unconformably overlain by Cretaceous strata. The Lower Elk Point Group is equivalent to the Stone Formation and its equivalents, and the Headless and

Nahanni Formation The Nahanni Formation is a stratigraphical unit of Givetian age in the Western Canadian Sedimentary Basin. It takes the name from Nahanni Butte, a prominent ridge at the confluence of the South Nahanni River and Liard River, and was first descri ...

s, in northerneastern British Columbia and the southwestern Northwest Territories. In the same areas, the Upper Elk Point includes the Pine Point Group, and is equivalent to parts of 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 out ...

Besa River Formation The Besa River Formation is a stratigraphical unit of Devonian age in the Western Canadian Sedimentary Basin. It takes the name from Besa River, a tributary of the Prophet River, and was first described in outcrop near the Muskwa River, in th ...

, and others.

Petroleum and Natural Gas

The porous carbonate rocks of the Elk Point Group host major

and

. 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.

References

{{Western Canadian Sedimentary Basin, Northeast_Plains=yes, Northwest_Plains=yes, South AB=yes, Saskatchewan=yes Geologic groups of the United States Geologic formations of Canada 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 Stratigraphy of Alberta Stratigraphy of British Columbia Stratigraphy of Saskatchewan Devonian System of North America Devonian southern paleotropical deposits Lower Devonian Series Middle Devonian Series Devonian southern paleotemperate deposits