The Three Forks Group 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 Famennian

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 Williston Basin. It takes the name from the city of Three Forks, Montana, and was first described in outcrop near the city by A.C. Peale in 1893 (for the Three Forks Shale).

Lithology

The Three Forks Group is composed of

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 ...

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 bituminous

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 ...

Hydrocarbon production

In the subsurface of the Williston Basin, the Three Forks is referred to as the Three Forks ''Formation'', which lies between the Birdbear Formation below, and the Bakken Formation above. Oil produced from the Three Forks Formation in the Williston Basin of North Dakota and south-eastern Saskatchewan is often included in production statistics with the overlying Bakken Formation. For instance, the Three Forks and Bakken were combined in estimates of potential production released by the United States Geological Survey on April 30, 2013. The estimate by the USGS projects that 7.4 billion barrels of oil can be recovered from the Bakken and Three Forks formations and 6.7 trillion cubic feet of natural gas and 530 million barrels of natural gas liquids using current technology.

Distribution

The Three Forks Group reaches a maximum thickness of , but can be as thin as .

Subdivisions

Relationship to other units

The Three Forks Group

conformably Lithostratigraphy is a sub-discipline of stratigraphy, the geological science associated with the study of strata or rock layers. Major focuses include geochronology, comparative geology, and petrology. In general, strata are primarily igne ...

overlies the

Saskatchewan Group The Saskatchewan Group is a Stratigraphy, stratigraphical unit of Frasnian Geochronology, age in the Western Canadian Sedimentary Basin. It takes the name from the province of Saskatchewan, and was first described in the ''Mobil Oil Woodley Sincl ...

and is disconformably overlain by the Madison Group. It is equivalent to the sum of the

Wabamun Group The Wabamun Formation is a stratigraphic unit of Late Devonian (Famennian) age in the Western Canada Sedimentary Basin. It takes the name from Wabamun Lake and was first described in the ''Anglo Canadian Wabamun Lake No. 1'' well (located between ...

and

Exshaw Formation The Exshaw Formation is a stratigraphic unit in the Western Canada Sedimentary Basin. It takes the name from the hamlet of Exshaw, Alberta in the Canadian Rockies, and was first described from outcrops on the banks of Jura Creek north of Exshaw by ...

in Alberta.

References

{{Western Canadian Sedimentary Basin, Saskatchewan=yes Stratigraphy of Saskatchewan Geologic groups of North Dakota Geologic groups of Montana Geologic groups of North America Carboniferous southern paleotemperate deposits Devonian southern paleotemperate deposits