The Basin and Range Province is a vast
physiographic region covering much of the inland
Western United States
The Western United States (also called the American West, the Far West, and the West) is the region comprising the westernmost states of the United States. As American settlement in the U.S. expanded westward, the meaning of the term ''the Wes ...
and
northwestern Mexico. It is defined by unique
basin and range topography, characterized by abrupt changes in elevation, alternating between narrow faulted mountain chains and flat arid valleys or basins. The
physiography of the province is the result of
tectonic extension that began around 17 million years ago in the early
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...
epoch.
The numerous ranges within the province in the United States are collectively referred to as the "Great Basin Ranges", although many are not actually in the
Great Basin. Major ranges include the
Snake Range
The Snake Range is a mountain range in White Pine County, Nevada, United States. The south-central portion of the range is included within Great Basin National Park, with most of the remainder included within the Humboldt-Toiyabe National Forest ...
, the
Panamint Range, the
White Mountains, and the
Sandia Mountains. The highest point fully within the province is
White Mountain Peak in
California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the ...
, while the lowest point is the
Badwater Basin in
Death Valley
Death Valley is a desert valley in Eastern California, in the northern Mojave Desert, bordering the Great Basin Desert. During summer, it is the hottest place on Earth.
Death Valley's Badwater Basin is the point of lowest elevation in North Am ...
at .
The province's climate is arid, with numerous
ecoregions. Most
North American deserts
North is one of the four compass points or cardinal directions. It is the opposite of south and is perpendicular to east and west. ''North'' is a noun, adjective, or adverb indicating direction or geography.
Etymology
The word ''north'' is ...
are located within it.
The Basin and Range Province should not be confused with the
Great Basin, a region defined by its unique hydrological characteristics (internal drainage) that overlaps much of the greater Basin and Range physiographic region. Nor should it be confused with the
Basin and Range National Monument, located in Southern Nevada, which is one small part of the much larger province.
Geography
The Basin and Range Province includes much of western
North America. In the United States, it is bordered on the west by the eastern
fault scarp of the
Sierra Nevada and spans over to its eastern border marked by the
Wasatch Fault, the
Colorado Plateau and the
Rio Grande Rift. The province extends north to the
Columbia Plateau and south as far as the
Trans-Mexican Volcanic Belt in
Mexico
Mexico ( Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guate ...
, though the southern boundaries of the Basin and Range are debated. In Mexico, the Basin and Range Province is dominated by and largely synonymous with the
Mexican Plateau.
Evidence suggests that the less-recognized southern portion of the province is bounded on the east by the
Laramide Thrust Front of the
Sierra Madre Oriental and on the west by the
Gulf of California and
Baja Peninsula with notably less faulting apparent in the
Sierra Madre Occidental in the center of the southernmost Basin and Range Province.
Common geographic features include numerous
endorheic basins, ephemeral lakes, plateaus, and valleys alternating with mountains (as described below). The area is mostly arid and sparsely populated, although there are several major metropolitan areas, such as
Reno,
Las Vegas
Las Vegas (; Spanish language, Spanish for "The Meadows"), often known simply as Vegas, is the List of United States cities by population, 25th-most populous city in the United States, the most populous city in the U.S. state, state of Neva ...
,
Salt Lake City
Salt Lake City (often shortened to Salt Lake and abbreviated as SLC) is the capital and most populous city of Utah, United States. It is the seat of Salt Lake County, the most populous county in Utah. With a population of 200,133 in 2020, th ...
,
Phoenix,
Tucson,
El Paso—
Ciudad Juárez,
Mexicali, and
Hermosillo.
Geology
It is generally accepted that basin and range topography is the result of extension and thinning of the
lithosphere, which is composed of
crust and
upper mantle. Extensional environments like the Basin and Range are characterized by
listric normal faulting, or faults that level out with depth. Opposing normal faults link at depth producing a
horst and
graben geometry, where horst refers to the upthrown fault block and graben to the down dropped fault block.
The average crustal thickness of the Basin and Range Province is approximately 30–35 km and is comparable to extended
continental crust around the world. The crust in conjunction with the upper mantle comprises the
lithosphere. The base of the lithosphere beneath the Basin and Range is estimated to be about 60–70 km. Opinions vary regarding the total extension of the region; however, the median estimate is about 100% total lateral extension. Total lateral displacement in the Basin and Range varies from 60 to 300 km since the onset of extension in the Early
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...
with the southern portion of the province representing a greater degree of displacement than the north. Evidence exists to suggest that extension initially began in the southern Basin and Range and propagated north over time.
Clarence Dutton famously compared the many narrow parallel mountain ranges that distinguish the unique topography of the Basin and Range to an "army of caterpillars crawling northward."
Tectonics
The tectonic mechanisms responsible for lithospheric extension in the Basin and Range province are controversial, and several competing hypotheses attempt to explain them. Key events preceding Basin and Range extension in the western United States include a long period of compression due to the
subduction of the
Farallon Plate under the west coast of the North American continental plate which stimulated the thickening of the crust. Most of the pertinent tectonic plate movement associated with the province occurred in
Neogene time and continues to the present. By Early
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...
time, much of the Farallon Plate had been consumed, and the
seafloor spreading ridge
A mid-ocean ridge (MOR) is a seafloor mountain system formed by plate tectonics. It typically has a depth of about and rises about above the deepest portion of an ocean basin. This feature is where seafloor spreading takes place along a diver ...
that separated the Farallon Plate from the
Pacific Plate (
Pacific-Farallon Ridge) approached North America.
In the Middle
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recent" ...
, the Pacific-Farallon Ridge was subducted beneath North America ending
subduction along this part of the Pacific margin; however, the Farallon Plate continued to subduct into the
mantle
A mantle is a piece of clothing, a type of cloak. Several other meanings are derived from that.
Mantle may refer to:
*Mantle (clothing), a cloak-like garment worn mainly by women as fashionable outerwear
**Mantle (vesture), an Eastern Orthodox ve ...
.
[ The movement at this boundary divided the Pacific-Farallon Ridge and spawned the San Andreas transform fault, generating an oblique strike-slip component. Today, the Pacific Plate moves north-westward relative to North America, a configuration which has given rise to increased shearing along the continental margin.][
The tectonic activity responsible for the extension in the Basin and Range is a complex and controversial issue among the geoscience community. The most accepted hypothesis suggests that crustal shearing associated with the San Andreas Fault caused spontaneous extensional faulting similar to that seen in the Great Basin.] However, plate movement alone does not account for the high elevation of the Basin and Range region.[ The western United States is a region of high heat flow which lowers the density of the lithosphere and stimulates isostatic uplift as a consequence. Lithospheric regions characterized by elevated heat flow are weak and extensional deformation can occur over a broad region. Basin and Range extension is therefore thought to be unrelated to the kind of extension produced by mantle upwelling which may cause narrow rift zones, such as those of the Afar Triple Junction. Geologic processes that elevate heat flow are varied, however some researchers suggest that heat generated at a subduction zone is transferred to the overriding plate as subduction proceeds. Fluids along fault zones then transfer heat vertically through the crust. This model has led to increasing interest in geothermal systems in the Basin and Range, and requires consideration of the continued influence of the fully subducted Farallon plate in the extension responsible for the Basin and Range Province.
]
Metamorphic core complexes
In some localities in the Basin and Range, metamorphic basement is visible at the surface. Some of these are metamorphic core complexes (MCC), an idea that was first developed based on studies in this province. A metamorphic core complex occurs when lower crust is brought to the surface as a result of extension. MCCs in the Basin and Range were not interpreted as being related to crustal extension until after the 1960s. Since then, similar deformational patterns have been identified in MCCs in the Basin and Range and has led geologists to examine them as a group of related geologic features formed by Cenozoic crustal extension. The study of metamorphic core complexes has provided valuable insight into the extensional processes driving Basin and Range formation.
Volcanism
Prior to the Eocene Epoch (55.8 ±0.2 to 33.9 ±0.1 Ma) the convergence rate of the Farallon and North American Plates was fast, the angle of subduction was shallow, and the slab width was huge. During the Eocene
The Eocene ( ) Epoch is a geological epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period in the modern Cenozoic Era. The name ''Eocene'' comes from the Ancient Greek (''ēṓs'', " ...
the Farallon Plate subduction-associated compressive forces of the Laramide, Sevier
Sevier ( ) is an unincorporated community in southwestern Sevier County, Utah, United States. It lies in the valley of the Sevier River along U.S. Route 89 southwest of the city of Richfield, the county seat of Sevier County. Its elevation is ...
and Nevada
Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
orogenies ended, plate interactions changed from orthogonal compression to oblique strike-slip, and volcanism in the Basin and Range Province flared up ( Mid-Tertiary ignimbrite flare-up). It is suggested that this plate continued to be underthrust until about 19 Ma, at which time it was completely consumed and volcanic activity ceased, in part. Olivine basalt from the oceanic ridge erupted around 17 Ma and extension began.
Volcanic areas
* Great Basin volcanism:
** Southwestern Nevada volcanic field (SWNVF)
** Réveille Range and Lunar Crater volcanic field
** Indian Peak volcanic field, Nevada
Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
/Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
** Marysvale volcanic field, Utah
Utah ( , ) is a state in the Mountain West subregion of the Western United States. Utah is a landlocked U.S. state bordered to its east by Colorado, to its northeast by Wyoming, to its north by Idaho, to its south by Arizona, and to its ...
* Mogollon-Datil volcanic field:
** Bursum
** Emory
** Organ ( Las Cruces, Doña Ana Mountains, Organ Mountains)
** Socorro caldera
Socorro is a Portuguese- Spanish noun meaning "help" or "relief" (cf. '' succor''). It may also refer to:
Places
* Socorro, São Paulo, a city in São Paulo state, Brazil
* Socorro (district of São Paulo), a district in São Paulo city, Br ...
s
* The Jemez Lineament
The Jemez Lineament is a chain of late Cenozoic volcanic fields, long, reaching from the Springerville and White Mountains volcanic fields in East-Central Arizona to the Raton-Clayton volcanic field in Northeastern New Mexico.
The lineamen ...
:
** San Carlos volcanic field
San Carlos volcanic field is a monogenetic volcanic field in Arizona. The field lies within the San Carlos Apache Reservation about east of Globe, Arizona. It is a small field covering approximately 50 km2 or less of volcanic cones and l ...
** Springerville volcanic field
Springerville volcanic field is a monogenetic volcanic field located in east-central Arizona between Springerville and Show Low. The field consists of 405 discrete vents covering approximately and is the third-largest such field in the contin ...
** Red Hill volcanic field
Red Hill volcanic field, also known as Quemado volcanic field, is a monogenetic volcanic field located in the vicinity of the ghost town of Red Hill in Catron County New Mexico. Red Hill is east of the larger Springerville volcanic field and ...
** Zuni-Bandera volcanic field
** Mount Taylor volcanic field
** Jemez volcanic field
The Jemez Mountains are a group of mountains in Rio Arriba, Sandoval, and Los Alamos counties, New Mexico, United States.
Numerous Puebloan Indian tribes have lived in the Jemez Mountains region since before the Spanish arrived in New Mexico. T ...
* Trans-Pecos volcanic field The Trans-Pecos Volcanic Field is a volcanic field located in western Texas in the counties of Brewster, Jeff Davis, Presidio, and extends into northern Mexican states of Chihuahua and Coahuila. It is the southernmost volcanic field to be docum ...
:
** Big Bend National Park
** Davis Mountains
Mineral resources
In addition to small amounts of Nevada
Nevada ( ; ) is a state in the Western region of the United States. It is bordered by Oregon to the northwest, Idaho to the northeast, California to the west, Arizona to the southeast, and Utah to the east. Nevada is the 7th-most extensive, ...
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 ...
, the Basin and Range Province supplies nearly all the copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish ...
and most of the gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
, silver
Silver is a chemical element with the Symbol (chemistry), symbol Ag (from the Latin ', derived from the Proto-Indo-European wikt:Reconstruction:Proto-Indo-European/h₂erǵ-, ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, whi ...
, and barite mined in the United States.
See also
* Cascade-Sierra province
* Intermontane Plateaus § Basin and Range Province
* List of United States physiographic regions
* Northern Snake Range metamorphic core complex
The Northern Snake Range metamorphic core complex is a gently domed structure that forms the northern part of the Snake Range. The metamorphic core complex consists of an upper plate of brittlely-faulted Cambrian to Permian mainly carbonate s ...
References
Further reading
*
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External links
*
{{DEFAULTSORT:Basin And Range Province
Physiographic provinces
Geologic provinces of the United States
Geology of Mexico
Physiographic regions of Mexico
Physiographic regions of the United States
Cenozoic rifts and grabens
Seismic faults of the United States
Structural geology
Geography of Chihuahua (state)
Geology of Utah
Geology of Idaho
Geology of New Mexico
Geology of Arizona
Geologic provinces of Texas
Geology of Oregon
Geography of Sonora
Geography of Wyoming
Regions of the Western United States