Debolt Formation
Encyclopedia
The Debolt Formation is a stratigraphical
unit of Meramecian age
in the Western Canadian Sedimentary Basin
.
It takes the name from the hamlet of Debolt, Alberta
, and was first described in the Amerada Crown GF23-11 well near Debolt by G. Macauley in 1958.
in the base, with dolomitized areas in the east and with increased shale
content in the north. Chert
and dolomite
are more frequent closer to the Canadian Rockies
foothills. The upper Debolt is composed of dolomite and anhydrite
and crystalline limestone
. The facies
is mainly limestone in north-eastern British Columbia
.
in northern Alberta
and north-eastern British Columbia
. The formation is 366 metres (1,200.8 ft) thick close to the Rocky Mountains
, and thins out northward and eastward. It has a thickness of 244 metres (800.5 ft) at its type locality near Debolt, Alberta
.
. It rests conformably on the Shunda Formation, resting on shale
and carbonate
s. It is overlain conformably by the Golata Formation of the Stoddart Group
in the west, and the upper contact becomes unconformable
with gradually newer formations to the east and north (Permian
, Triassic
, Jurassic
and Cretaceous
beds).
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 Meramecian 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 hamlet of Debolt, Alberta
Debolt, Alberta
DeBolt is a hamlet in northern Alberta, Canada within the Municipal District of Greenview No. 16. The hamlet's name is often mistakenly spelled Debolt, even by Statistics Canada. It was named after the DeBolt family, who settled the area in 1919.The hamlet is located in census division No...
, and was first described in the Amerada Crown GF23-11 well near Debolt by G. Macauley in 1958.
Lithology
The Debolt Formation consists of bioclastic limestoneLimestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
in the base, with dolomitized areas in the east and with increased 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...
content in the north. Chert
Chert
Chert is a fine-grained silica-rich microcrystalline, cryptocrystalline or microfibrous sedimentary rock that may contain small fossils. It varies greatly in color , but most often manifests as gray, brown, grayish brown and light green to rusty red; its color is an expression of trace elements...
and dolomite
Dolomite
Dolomite is a carbonate mineral composed of calcium magnesium carbonate CaMg2. The term is also used to describe the sedimentary carbonate rock dolostone....
are more frequent closer to 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. The upper Debolt is composed of dolomite and anhydrite
Anhydrite
Anhydrite is a mineral – anhydrous calcium sulfate, 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 orthorhombic barium and strontium sulfates, as might be expected from the...
and crystalline limestone
Limestone
Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate . Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera....
. The 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....
is mainly limestone in north-eastern 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...
.
Distribution
The Debolt Formation is present in the sub-surface in the 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...
in northern Alberta
Northern Alberta
Northern Alberta is a region located in the Canadian province of Alberta.Its primary industry is oil and gas, with large heavy oil reserves being exploited at the Athabasca Oil Sands and Wabasca Area in the east of the region...
and north-eastern 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...
. The formation is 366 metres (1,200.8 ft) thick close to the Rocky Mountains
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
, and thins out northward and eastward. It has a thickness of 244 metres (800.5 ft) at its type locality near Debolt, Alberta
Debolt, Alberta
DeBolt is a hamlet in northern Alberta, Canada within the Municipal District of Greenview No. 16. The hamlet's name is often mistakenly spelled Debolt, even by Statistics Canada. It was named after the DeBolt family, who settled the area in 1919.The hamlet is located in census division No...
.
Relationship to other units
The Debolt Formation is the upper most component of the Rundle GroupRundle Group
The Rundle Group is a stratigraphical unit of Mississippian age in the Western Canadian Sedimentary Basin.It takes the name from Mount Rundle , and was first described in outcrops at the northern side of the mountain in Banff National Park by R.J.W...
. It rests conformably on the Shunda Formation, resting on 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...
and carbonate
Carbonate
In chemistry, a carbonate is a salt of carbonic acid, characterized by the presence of the carbonate ion, . The name may also mean an ester of carbonic acid, an organic compound containing the carbonate group C2....
s. It is overlain conformably by the Golata Formation of the Stoddart Group
Stoddart Group
The Stoddart Group is a stratigraphical unit of Mississippian to Early Pennsylvanian age in the Western Canadian Sedimentary Basin.It takes the name from the Stoddart Creek, a creek that flows into Charlie Lake north of Fort St. John, and was first described in well Pacific Fort St. John #23 by...
in the west, and the upper contact becomes unconformable
Unconformity
An unconformity is a buried erosion 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 of time before deposition of the younger, but the term is used to describe...
with gradually newer formations to the east and north (Permian
Permian
The PermianThe term "Permian" was introduced into geology in 1841 by Sir Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil; Murchison asserted in 1841 that he named his "Permian...
, Triassic
Triassic
The Triassic is a geologic period and system that extends from about 250 to 200 Mya . As the first period of the Mesozoic Era, the Triassic follows the Permian and is followed by the Jurassic. Both the start and end of the Triassic are marked by major extinction events...
, Jurassic
Jurassic
The Jurassic is a geologic period and system that extends from about Mya to Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic era, also known as the age of reptiles. The start of the period is marked by...
and Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...
beds).