The Williston Basin is a large
intracratonic sedimentary
Sedimentary rocks are types of rock that are formed by the accumulation or deposition of mineral or organic particles at Earth's surface, followed by cementation. Sedimentation is the collective name for processes that cause these particles ...
basin in 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 Colu ...
, western
North Dakota
North Dakota () is a U.S. state in the Upper Midwest, named after the indigenous Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north and by the U.S. states of Minnesota to the east, ...
,
South Dakota
South Dakota (; Sioux: , ) is a U.S. state in the North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota and Dakota Sioux Native American tribes, who comprise a large portio ...
, southern
Saskatchewan
Saskatchewan ( ; ) is a province in 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 the south by the U.S. states of Montana and North Da ...
, and south-western
Manitoba
, image_map = Manitoba in Canada 2.svg
, map_alt = Map showing Manitoba's location in the centre of Southern Canada
, Label_map = yes
, coordinates =
, capital = Winn ...
that is known for its rich deposits of
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 crude ...
and
potash
Potash () includes various mined and manufactured salts that contain potassium in water-soluble form. . The basin is a geologic
structural basin
A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat-lying strata. They are geological depressions, the inverse of domes. Elongated structural basins are also known as synclines. ...
but not a
topographic
Topography is the study of the forms and features of land surfaces. The topography of an area may refer to the land forms and features themselves, or a description or depiction in maps.
Topography is a field of geoscience and planetary scie ...
depression; it is transected by the
Missouri River. The oval-shaped depression extends approximately north-south and east-west.
The Williston Basin lies above an ancient
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 t ...
geologic basement feature, the
Trans-Hudson Orogenic Belt that developed in this area about 1.8-1.9 billion years ago, and that created a weak zone that later led to sagging to produce the basin. The Precambrian basement rocks in the center of the basin beneath the city of
Williston, North Dakota
Williston is a city in and the county seat of Williams County, North Dakota, Williams County, North Dakota, United States. The 2020 United States census, 2020 census gave its population as 29,160, making Williston the List of cities in North Dako ...
lie about below the surface.
Deposition of sediments began in the Williston area during
Cambrian
The Cambrian Period ( ; sometimes symbolized 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 years ag ...
time, but subsidence and basin filling were most intense during the
Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya.
T ...
,
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 ...
, and
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, w ...
Periods, when thick accumulations of limestone and dolomite, with lesser thicknesses of sandstones, siltsones, shales, and
evaporites
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 ocean ...
were laid down. Subsidence continued on a reduced scale into the
Mississippian and was largely ended by
Pennsylvanian time. Regional subsidence returned during the
Mesozoic
The Mesozoic Era ( ), also called the Age of Reptiles, the Age of Conifers, and colloquially as the Age of the Dinosaurs is the second-to-last era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceo ...
Era, although total sediment thicknesses were much less than during the
Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ...
. Near the end of the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, tectonic activity during the
Laramide Orogeny
The Laramide orogeny was a time period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. The exact duration and ages of beginning and end of the ...
rejuvenated several basement structures in the Williston Basin to produce anticlines that serve as oil traps today.
Natural resources
Petroleum
The long history of sedimentary deposition in the Williston Basin included deposition of rocks well suited to serve as hydrocarbon
source and
reservoir rocks. The basin's oil and gas fields are found in a wide range of geologic ages, as indicated by the generalized stratigraphic column.
[Peterson, J., Williston Basin Province, ''in'' U. S. Geological Survey 1995 National Assessment of United States Oil and Gas Resources, Digital Data Series DDS-30, Release 2, CD-ROM]
In 1913, shallow gas was discovered in an
Upper Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', t ...
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) ...
on the Cedar Creek
Anticline
In structural geology, an anticline is a type of fold that is an arch-like shape and has its oldest beds at its core, whereas a syncline is the inverse of an anticline. A typical anticline is convex up in which the hinge or crest is the ...
, and oil was discovered on the same anticline in 1936. The basin did not become a major oil province until the 1950s when large fields were discovered in North Dakota.
Amerada Corporation began the search in 1946. After four years of testing and mapping they started drilling at a promising lease 30 miles north-east of
Williston, North Dakota
Williston is a city in and the county seat of Williams County, North Dakota, Williams County, North Dakota, United States. The 2020 United States census, 2020 census gave its population as 29,160, making Williston the List of cities in North Dako ...
, and on April 4, 1951, discovered oil on the Nesson Anticline, with the Amerada Hess Corporation Clarence Iverson #1 well. Other
oil firms rushed in to buy up leases on farm land to explore for oil and by 1954 80% of the possible oil producing areas were under lease. Shell at that time had leases over 8 million acres. Many local farmers and area speculators became instant millionaires, leasing land at an average of $25 an acre and then selling those leases back at a much higher cost per acre. Production peaked in 1986, but in the early 2000s significant increases in production began because of application of
horizontal drilling
Directional drilling (or slant drilling) is the practice of drilling non-vertical bores. It can be broken down into four main groups: oilfield directional drilling, utility installation directional drilling, directional boring (horizontal dir ...
techniques, especially in the
Bakken Formation
The Bakken Formation () is a rock unit from the Late Devonian to Early Mississippian age occupying about of the subsurface of the Williston Basin, underlying parts of Montana, North Dakota, Saskatchewan and Manitoba. The formation was init ...
.
Cumulative basin production totals about of oil and of natural gas. The largest oil fields are listed in the following table, showing estimated ultimate recoveries.
Potash
Potash
Potash () includes various mined and manufactured salts that contain potassium in water-soluble form. produced from the Williston Basin makes Canada the world's leading producer of that commodity. The deposits occur in the
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 ...
Prairie Formation. Major potash-producing companies include
Nutrien and Mosaic.
Coal
The Williston Basin holds large coal deposits, primarily in the
Fort Union Formation of mostly
Paleogene
The Paleogene ( ; also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period million years ago ( Mya) to the beginning o ...
age, and were first noted during the
Lewis and Clark Expedition
The Lewis and Clark Expedition, also known as the Corps of Discovery Expedition, was the United States expedition to cross the newly acquired western portion of the country after the Louisiana Purchase. The Corps of Discovery was a select g ...
. Mining of the coal began in 1873 near
Sims, North Dakota, but was soon abandoned. The
Northern Pacific Railway
The Northern Pacific Railway was a transcontinental railroad that operated across the northern tier of the western United States, from Minnesota to the Pacific Northwest. It was approved by Congress in 1864 and given nearly of land grants, wh ...
took over the mine and developed the
lignite
Lignite, often referred to as brown coal, is a soft, brown, combustible, sedimentary rock formed from naturally compressed peat. It has a carbon content around 25–35%, and is considered the lowest rank of coal due to its relatively low hea ...
beds as the Northern Pacific Coal Company. Other mines followed near
Minot, North Dakota
Minot ( ) is a city in and the county seat of Ward County, North Dakota, United States, in the state's north-central region. It is most widely known for the Air Force base approximately north of the city. With a population of 48,377 at the 2 ...
and
Dickinson, North Dakota
Dickinson is a city in and the county seat of Stark County, North Dakota, United States. The population was 25,679 at the 2020 census. Dickinson is home to the Ukrainian Cultural Institute, which has a museum and holds events year round for the ...
, and the period from 1900 to 1920 saw a large-scale increase in the lignite industry.
Strip-mining was common from 1920 until 1940, and 320 mines were in operation by 1940. However, production peaked in 1951, and by 1965, only 38 mines were in operation, while by 1999, only 4.
Helium
In 1952,
helium
Helium (from el, ἥλιος, helios, lit=sun) is a chemical element with the symbol He and atomic number 2. It is a colorless, odorless, tasteless, non-toxic, inert, monatomic gas and the first in the noble gas group in the periodic table ...
concentrations were discovered in southwestern Saskatchewan. Production from four wells took place from 1963 to 1977, and resumed again in 2014. The Deadwood Formation, and other Lower
Paleozoic
The Paleozoic (or Palaeozoic) Era is the earliest of three geologic eras of the Phanerozoic Eon.
The name ''Paleozoic'' ( ;) was coined by the British geologist Adam Sedgwick in 1838
by combining the Greek words ''palaiós'' (, "old") and ...
formations, had the highest concentration. The helium originated through natural
radioactive decay
Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consid ...
of
uranium
Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...
and
thorium
Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high ...
in
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 t ...
granitic
A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from qua ...
basement
A basement or cellar is one or more floors of a building that are completely or partly below the ground floor. It generally is used as a utility space for a building, where such items as the furnace, water heater, breaker panel or fuse ...
rocks, or Lower Paleozoic
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 ...
s.
Geology
The
Upper Cambrian Deadwood Formation was
transgressively deposited on the low-relief
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 t ...
surface. The Deadwood is characterized by
shallow marine and
coastal plain
A coastal plain is flat, low-lying land adjacent to a sea coast. A fall line commonly marks the border between a coastal plain and a piedmont area. Some of the largest coastal plains are in Alaska and the southeastern United States. The Gulf ...
sediments, with abundant
glauconite
Glauconite is an iron potassium phyllosilicate ( mica group) mineral of characteristic green color which is very friable and has very low weathering resistance.
It crystallizes with a monoclinic geometry. Its name is derived from the Greek ...
giving the formation a distinctive green color. The basin started
subsiding due to
strike-slip movement along northeast–southwest trending
faults, resulting in the deposition of the Winnipeg Group, which lies
unconformably on the Deadwood. The Winnipeg consists of shallow marine sandstone, shale and shaly
carbonate
A carbonate is a salt of carbonic acid (H2CO3), characterized by the presence of the carbonate ion, a polyatomic ion with the formula . The word ''carbonate'' may also refer to a carbonate ester, an organic compound containing the carbonate g ...
. The
Red River Formation lies unconformably on the Winnipeg, and consists of shallow marine carbonate,
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
salt
Salt is a mineral composed primarily of sodium chloride (NaCl), a chemical compound belonging to the larger class of salts; salt in the form of a natural crystalline mineral is known as rock salt or halite. Salt is present in vast quantiti ...
sedimentation
Sedimentation is the deposition of sediments. It takes place when particles in suspension settle out of the fluid in which they are entrained and come to rest against a barrier. This is due to their motion through the fluid in response to th ...
. Conformably overlying the Red River is the
Ordovician
The Ordovician ( ) is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.6 million years from the end of the Cambrian Period million years ago (Mya) to the start of the Silurian Period Mya.
T ...
Stony Mountain Formation and
Stonewall Formation, followed by the
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 ...
Interlake Group. During the
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, w ...
, the Williston Basin became the southeastern corner of the Elk Point Basin when the
Elk Point Group,
Manitoba Group, and
Saskatchewan Group were deposited. The
Bakken Formation
The Bakken Formation () is a rock unit from the Late Devonian to Early Mississippian age occupying about of the subsurface of the Williston Basin, underlying parts of Montana, North Dakota, Saskatchewan and Manitoba. The formation was init ...
, an
organic-rich marine shale, was deposited in the Late Devonian. The
Lodgepole Limestone was deposited during the
Mississippian, followed by the
Madison Group
The Madison Limestone is a thick sequence of mostly carbonate rocks of Mississippian age in the Rocky Mountain and Great Plains areas of the western United States. The rocks serve as an important aquifer as well as an oil reservoir in places. Th ...
and the
Big Snowy Group. The Tyler Formation was deposited in the
Pennsylvanian, and consists of
interbedded
In geology, interbedding occurs when beds (layers of rock) of a particular lithology lie between or alternate with beds of a different lithology. For example, sedimentary rocks may be interbedded if there were sea level variations in their sedime ...
sandstone,
siltstone
Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt. It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.Blatt ''et al.'' 1980 ...
, shale, 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 wh ...
. The overlying
Minnelusa Formation is characterized by deposition in
alluvial plain
An alluvial plain is a largely flat landform created by the deposition of sediment over a long period of time by one or more rivers coming from highland regions, from which alluvial soil forms. A floodplain is part of the process, being the smal ...
s,
prograding river delta
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 ...
, and
barrier island
Barrier islands are coastal landforms and a type of dune system that are exceptionally flat or lumpy areas of sand that form by wave and tidal action parallel to the mainland coast. They usually occur in chains, consisting of anything from ...
environments. The
Minnekahta Formation was deposited during the
Permian
The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Paleoz ...
, followed by the
Spearfish Formation and the Nesson Formation. The
Pierre Shale
The Pierre Shale is a geologic formation or series in the Upper Cretaceous which occurs east of the Rocky Mountains in the Great Plains, from Pembina Valley in Canada to New Mexico.
The Pierre Shale was described by Fielding Bradford Meek, Meek a ...
was deposited curing the
Cretaceous
The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...
, followed by the
Hell Creek Formation
The Hell Creek Formation is an intensively studied division of mostly Upper Cretaceous and some lower Paleocene rocks in North America, named for exposures studied along Hell Creek, near Jordan, Montana. The formation stretches over portions o ...
, and the
Tertiary
Tertiary ( ) is a widely used but obsolete term for the geologic period from 66 million to 2.6 million years ago.
The period began with the demise of the non- avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start ...
Fort Union Formation.
Impact craters
Several confirmed
impact crater
An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact crater ...
s are located in Williston Basin such as
Viewfield,
Red Wing Creek, and
Eagle Butte while the Dumas and Hartney craters are still unconfirmed.
See also
*
List of possible impact structures on Earth
References
External links
Discovery of oil in the Williston Basin
{{Coord, 49, N, 104, W, format=dms, display=title, type:adm1st_region:US-MT_scale:5000000
Sedimentary basins of North America
Structural basins of Canada
Structural basins of the United States
Geology of Montana
Geology of North Dakota
Geology of Saskatchewan
Geologic provinces of the United States