Dunvegan Formation
Encyclopedia
The Dunvegan Formation is a stratigraphical
unit of Cenomanian
age
in the Western Canadian Sedimentary Basin
.
It takes the name from the settlement of Dunvegan, Alberta
, and was first described in an outcrop on Peace River
near Dunvegan by George Mercer Dawson
in 1881.
, and deltaic sandstone
with thin shale
interbeds in the Peace River Country. East of Dunvegan
it is of marine origin, and in its western reaches in British Columbia it was deposited in a continental
facies
, where the sandstone becomes more conglomeratic
. Brackish water
environment was present in the Wapiti River
area and south of Grande Prairie
, where the formation is porous
.
reserve
of 9.9 million m³, with 3.1 million m³ already produced as of 2008. Gas
reserves totaled 18.7 million m³, with 4.5 million m³ already produced.
and up to 380 feet (115.8 m) in the sub-surface of the Canadian Rockies
foothills. It occurs south of Fort Nelson
and the Liard River
in north-east British Columbia
, thins out south of the Peace River Country and disappears south of the Athabasca River
.
The Dunvegan Formation is exposed in outcrop along and near the Peace River
east of the foothills, in the Peace River Country
and the Chinchaga area, as well as patches in north-western Alberta and south of the Caribou Mountains
.
in the Peace River Country and overlies conformably and transitionally the shale
of the Fort St. John Group
.
Stratigraphy
Stratigraphy, a branch of geology, studies rock layers and layering . It is primarily used in the study of sedimentary and layered volcanic rocks....
unit of Cenomanian
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 stratigraphic column deposited during the corresponding...
age
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...
in the Western Canadian Sedimentary Basin
Western Canadian Sedimentary Basin
The Western Canadian Sedimentary Basin is a vast sedimentary basin underlying of Western Canada including southwestern Manitoba, southern Saskatchewan, Alberta, northeastern British Columbia and the southwest corner of the Northwest Territories. It consists of a massive wedge of sedimentary rock...
.
It takes the name from the settlement of Dunvegan, Alberta
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 Dunvegan Creek....
, and was first described in an outcrop on Peace River
Peace River (Canada)
The Peace River 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 flows into the Slave River, a tributary of the Mackenzie River. The Mackenzie is the 12th longest river in the world,...
near Dunvegan by George Mercer Dawson
George Mercer Dawson
Dr. George Mercer Dawson F.R.S., C.M.G., was a Canadian scientist and surveyor. He was born in Pictou, Nova Scotia, the eldest son of Sir John William Dawson, Principal of McGill University and his wife, Lady Margaret Dawson...
in 1881.
Lithology
The Dunvegan Formation is composed of marineMarine (ocean)
Marine is an umbrella term. As an adjective it is usually applicable to things relating to the sea or ocean, such as marine biology, marine ecology and marine geology...
, and deltaic sandstone
Sandstone
Sandstone is a sedimentary rock composed mainly of sand-sized minerals or rock grains.Most sandstone is composed of quartz and/or feldspar because these are the most common minerals in the Earth's crust. Like sand, sandstone may be any colour, but the most common colours are tan, brown, yellow,...
with thin shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
interbeds in the Peace River Country. East of Dunvegan
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 Dunvegan Creek....
it is of marine origin, and in its western reaches in British Columbia it was deposited in a continental
Continental
Continental is the adjective form of continent.Continental may also refer to:* Continental , an album by UK band Saint Etienne* Continental , a brand of dried and pre-packaged foods used by Unilever in Australia...
facies
Facies
In geology, facies are a body of rock with specified characteristics. Ideally, a facies is a distinctive rock unit that forms under certain conditions of sedimentation, reflecting a particular process or environment....
, where the sandstone becomes more conglomeratic
Conglomerate (geology)
A conglomerate is a rock consisting of individual clasts within a finer-grained matrix that have become cemented together. Conglomerates are sedimentary rocks consisting of rounded fragments and are thus differentiated from breccias, which consist of angular clasts...
. Brackish water
Brackish water
Brackish water is water that has more salinity than fresh water, but not as much as seawater. It may result from mixing of seawater with fresh water, as in estuaries, or it may occur in brackish fossil aquifers. The word comes from the Middle Dutch root "brak," meaning "salty"...
environment was present in the Wapiti River
Wapiti River
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 .-Course:...
area and south of Grande Prairie
Grande Prairie, Alberta
Grande Prairie is a city in the northwestern part of the province of Alberta in Western Canada. It is located on the southern edge of the Peace River Country . The city is surrounded by the County of Grande Prairie No...
, where the formation is porous
Porosity
Porosity or void fraction is a measure of the void spaces in a material, and is a fraction of the volume of voids over the total volume, between 0–1, or as a percentage between 0–100%...
.
Hydrocarbon production
The Dunvegan Formation had an initial established recoverable oilPetroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
reserve
Oil reserves
The total estimated amount of oil in an oil reservoir, including both producible and non-producible oil, is called oil in place. However, because of reservoir characteristics and limitations in petroleum extraction technologies, only a fraction of this oil can be brought to the surface, and it is...
of 9.9 million m³, with 3.1 million m³ already produced as of 2008. Gas
Natural gas
Natural gas is a naturally occurring gas mixture consisting primarily of methane, typically with 0–20% higher hydrocarbons . It is found associated with other hydrocarbon fuel, in coal beds, as methane clathrates, and is an important fuel source and a major feedstock for fertilizers.Most natural...
reserves totaled 18.7 million m³, with 4.5 million m³ already produced.
Distribution
The Dunvegan Formation is 180 feet (54.9 m) thick in its type locallity in Peace River CountryPeace River Country
The Peace River Country is an aspen parkland region around the Peace River in Canada. It spans from northwestern Alberta to the Rocky Mountains in northeastern British Columbia, where the region is also referred to as the Peace River Block.- Geography :The Peace River Country includes the...
and up to 380 feet (115.8 m) in the sub-surface of the Canadian Rockies
Canadian Rockies
The Canadian Rockies comprise the Canadian segment of the North American Rocky Mountains range. They are the eastern part of the Canadian Cordillera, extending from the Interior Plains of Alberta to the Rocky Mountain Trench of British Columbia. The southern end borders Idaho and Montana of the USA...
foothills. It occurs south of Fort Nelson
Fort Nelson, British Columbia
Fort Nelson is a town of approximately 5000 residents in British Columbia's northeastern corner. It is the administrative centre of the newly formed Northern Rockies Regional Municipality, a first for BC. The majority of Fort Nelson's economic activities have historically been concentrated in the...
and the Liard River
Liard River
The Liard River 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 Columbia, marking the northern end of the Rocky Mountains and then curving northeast back...
in north-east British Columbia
British Columbia
British Columbia is the westernmost of Canada's provinces and is known for its natural beauty, as reflected in its Latin motto, Splendor sine occasu . Its name was chosen by Queen Victoria in 1858...
, thins out south of the Peace River Country and disappears south of the Athabasca River
Athabasca River
The Athabasca River originates from the Columbia Glacier of the Columbia Icefield in Jasper National Park in Alberta, Canada...
.
The Dunvegan Formation is exposed in outcrop along and near the Peace River
Peace River (Canada)
The Peace River 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 flows into the Slave River, a tributary of the Mackenzie River. The Mackenzie is the 12th longest river in the world,...
east of the foothills, in the Peace River Country
Peace River Country
The Peace River Country is an aspen parkland region around the Peace River in Canada. It spans from northwestern Alberta to the Rocky Mountains in northeastern British Columbia, where the region is also referred to as the Peace River Block.- Geography :The Peace River Country includes the...
and the Chinchaga area, as well as patches in north-western Alberta and south of the Caribou Mountains
Caribou Mountains (Alberta)
The Caribou Mountains are a mountain range surrounding an elevated plateau in northern Alberta, Canada and which rise north of the lower Peace River, and are bounded to the north and east by the Wood Buffalo National Park....
.
Relationship to other units
The Dunvegan Formation is conformably overlain by the Kaskapau FormationKaskapau Formation
The Kaskapau Formation is a geological formation in North America whose strata date back to the Late Cretaceous.The name derives from kaskapahtew , the Cree word for "smoky".. It was first described on the banks of the Smoky River, close to the confluence with the Puskwaskau River by F.H...
in the Peace River Country and overlies conformably and transitionally the shale
Shale
Shale is a fine-grained, clastic sedimentary rock composed of mud that is a mix of flakes of clay minerals and tiny fragments of other minerals, especially quartz and calcite. The ratio of clay to other minerals is variable. Shale is characterized by breaks along thin laminae or parallel layering...
of the Fort St. John Group
Fort St. John Group
The Fort St. John Group is a stratigraphical unit of Lower Cretaceous age in the Western Canadian 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:...
.