The Dunvegan Formation is a

stratigraphical 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

Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or earliest age of the Late Cretaceous Epoch or the lowest stage of the Upper Cretaceous Series. An age is a unit of geochronology; it is a unit of time; the stage is a unit in the s ...

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 Canadian Sedimentary Basin The Western Canadian 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 ...

. It takes the name from the settlement of

Dunvegan, Alberta Dunvegan ( ) is an unincorporated community within the Municipal District of Fairview No. 136 in northern Alberta, Canada. It is located south of the town of Fairview on the northern bank of the Peace River at the mouth of the Hines Creek. H ...

, and was first described in an outcrop on

Peace River The Peace River (french: links=no, rivière de la Paix) is a river in Canada that originates in the Rocky Mountains of northern British Columbia and flows to the northeast through northern Alberta. The Peace River joins the Athabasca River in th ...

near Dunvegan by

George Mercer Dawson George Mercer Dawson (August 1, 1849 – March 2, 1901) was a Canadian geologist and surveyor. Biography He was born in Pictou, Nova Scotia, the eldest son of Sir John William Dawson, Principal of McGill University and a noted geologis ...

in 1881.

Lithology

The Dunvegan Formation is composed of

marine Marine is an adjective meaning of or pertaining to the sea or ocean. Marine or marines may refer to: Ocean * Maritime (disambiguation) * Marine art * Marine biology * Marine debris * Marine habitats * Marine life * Marine pollution Military * ...

, and

deltaic A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rare ...

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

with thin

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 ...

interbeds in the Peace River Country. East of

it is of marine origin, and in its western reaches in British Columbia it was deposited in a

continent A continent is any of several large landmasses. Generally identified by convention rather than any strict criteria, up to seven geographical regions are commonly regarded as continents. Ordered from largest in area to smallest, these seven ...

facies In geology, a facies ( , ; same pronunciation and spelling in the plural) is a body of rock with specified characteristics, which can be any observable attribute of rocks (such as their overall appearance, composition, or condition of formatio ...

, where the sandstone becomes more conglomeratic. During Dunvegan time, a

brackish water Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estua ...

environment was present in the

Wapiti River The Wapiti River is a river in eastern British Columbia and western Alberta, Canada. It is a major tributary of the Smoky River, located in the southern area of the Peace River Basin. Wapiti is named after the Cree word for elk (''waapiti''). ...

area and south of

Grande Prairie Grande Prairie is a city in northwest Alberta, Canada within the southern portion of an area known as Peace River Country. It is located at the intersection of Highway 43 (part of the CANAMEX Corridor) and Highway 40 (the Bighorn Highway), a ...

, where the formation is

porous Porosity or void fraction is a measure of the void (i.e. "empty") spaces in a material, and is a fraction of the volume of voids over the total volume, between 0 and 1, or as a percentage between 0% and 100%. Strictly speaking, some tests measure ...

Hydrocarbon production

The Dunvegan Formation had an initial established recoverable

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

reserve Reserve or reserves may refer to: Places * Reserve, Kansas, a US city * Reserve, Louisiana, a census-designated place in St. John the Baptist Parish * Reserve, Montana, a census-designated place in Sheridan County * Reserve, New Mexico, a US vi ...

of 9.9 million m³, with 3.1 million m³ already produced as of 2008.

Gas Gas is one of the four fundamental states of matter (the others being solid, liquid, and plasma). A pure gas may be made up of individual atoms (e.g. a noble gas like neon), elemental molecules made from one type of atom (e.g. oxygen), or ...

reserves totaled 18.7 million m³, with 4.5 million m³ already produced.

Distribution

The Dunvegan Formation is thick in its type locality in

Peace River Country The Peace River Country (or Peace Country; french: Région de la Rivière-de-la-paix) is an aspen parkland region centring on the Peace River in Canada. It extends from northwestern Alberta to the Rocky Mountains in northeastern British Columbia, ...

and up to in the sub-surface of the

Canadian Rockies The Canadian Rockies (french: Rocheuses canadiennes) 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 ...

foothills. It occurs south of

Fort Nelson Fort Nelson may refer to: Canada *Fort Nelson, British Columbia, a town *Fort Nelson River, British Columbia * Fort Nelson (Manitoba) (1670–1713), an early fur trading post at the mouth of the Nelson River and the first headquarters of the Hudson ...

and the

Liard River The Liard River of the North American boreal forest flows through Yukon, British Columbia and the Northwest Territories, Canada. Rising in the Saint Cyr Range of the Pelly Mountains in southeastern Yukon, it flows southeast through British Co ...

in north-east

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, ...

, thins out south of the Peace River Country. South of the

Athabasca River The Athabasca River (French: ''Rivière Athabasca'') is a river in Alberta, Canada, which originates at the Columbia Icefield in Jasper National Park and flows more than before emptying into Lake Athabasca. Much of the land along its banks is pro ...

, the Dunvegan grades laterally into the Blackstone Formation. The Dunvegan Formation is exposed in outcrop along and near the

east of the foothills, in the

and the

Chinchaga Chinchaga Wildland Provincial Park is a wildland provincial park in northwestern Alberta, Canada. The park is a environmentally protected tract of land within the of the greater Chinchaga wilderness area. It is a disjunct outlier of the Footh ...

area, as well as patches in north-western Alberta and south of the Caribou Mountains.

Relationship to other units

The Dunvegan Formation is conformably overlain by marine shales of the

Kaskapau Formation The Kaskapau Formation is a geological formation in North America whose strata date back to the Late Cretaceous. The name derives from ''kaskapahtew'' (ᑲᐢᑲᐸᐦᑌᐤ), the Cree word for "smoky". It was first described on the banks of the ...

in the Peace River Country and overlies conformably and transitionally the

of the

Fort St. John Group The Fort St. John Group is a stratigraphic unit of Lower Cretaceous age in the Western Canada Sedimentary Basin. It takes the name from the city of Fort St. John, British Columbia and was first defined by George Mercer Dawson in 1881. Lithology T ...

. The relationship between the Dunvegan and the overlying/underlying units is

diachronous In geology, a diachronism (Greek language, Greek ''dia'', "through" + ''chronos'', "time" + ''-ism''), or diachronous deposit, is a sedimentary rock formation in which the material, although of a similar nature, varies in age with the place where i ...

and the boundaries of the Dunvegan are placed at the first and last appearances of sandstone within the shale-dominated succession.

References

{{Western Canadian Sedimentary Basin, Northwest_Plains=yes, Fort_Nelson=yes Stratigraphy of Alberta Stratigraphy of British Columbia Upper Cretaceous Series of North America Cenomanian Stage Sandstone formations of Canada Deltaic deposits Shallow marine deposits Reservoir rock formations