Maria Fold and Thrust Belt
Encyclopedia
The Maria fold and thrust belt (MFTB) is a portion of the North American Cordillera
orogen in which geological structures accommodate roughly north-south to northwest-southeast vergent
Mesozoic
age crustal shortening. This lies in contrast to the remainder of the Cordillera, in which shortening is predominantly East-West. Structures associated with the Maria Fold and Thrust Belt are exposed in a series of mountain ranges in southeastern California
and western Arizona
. Many of the deep structures of the MFTB have been exposed due to east-west to northeast-southwest Cenezoic age extension and unroofing.
In some parts of this fold-and-thrust-belt region, the extension resulted in the emplacement of metamorphic core complex
es, the 'type example' of which is defined by the Whipple Mountains
in southeastern California.
of the Farallon slab
beneath western North America. At the Maria fold-and-thrust-belt, compressional deformation shifts to being generally north-south, with the front of the mountain ranges being defined by a roughly east-west line. This line then shifts gently to the east-southeast, where the Cordilleran deformation diffuses into a broad shear zone
in northeastern Mexico
.
Another notable feature that differentiates it from the rest of the Cordillera is that the deformation involves the rocks of the North American craton. Deformation in the remainder of the Cordillera only involves rocks that were part of the near-shore and offshore, sedimentary sequences.
does not extend north of the Maria fold-and-thrust-belt, or more specifically the Turtle Mountains
.
and north-western Sonoran deserts, including the:
appears as part of the central and northern perimeter of the Maria fold-and-thrust-belt, approximately paralleling the Rawhide Mountains
, a slight northwest range on west end.)
North American Cordillera
The North American Cordillera is the North American portion of the American Cordillera which is a cordillera extending up and down the western side of the Americas. The North American Cordillera covers an extensive area of mountain ranges, intermontane basins, and plateaus in western North...
orogen in which geological structures accommodate roughly north-south to northwest-southeast vergent
Vergence (geology)
In structural geology, the vergence of a fold is the direction in which an antiform is inclined or overturned. The term vergence comes from the German vergenz, which means "overturn"....
Mesozoic
Mesozoic
The Mesozoic era is an interval of geological time from about 250 million years ago to about 65 million years ago. It is often referred to as the age of reptiles because reptiles, namely dinosaurs, were the dominant terrestrial and marine vertebrates of the time...
age crustal shortening. This lies in contrast to the remainder of the Cordillera, in which shortening is predominantly East-West. Structures associated with the Maria Fold and Thrust Belt are exposed in a series of mountain ranges in southeastern California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
and western Arizona
Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...
. Many of the deep structures of the MFTB have been exposed due to east-west to northeast-southwest Cenezoic age extension and unroofing.
In some parts of this fold-and-thrust-belt region, the extension resulted in the emplacement of metamorphic core complex
Metamorphic core complex
Metamorphic core complexes are exposures of deep crust exhumed in association with largely amagmatic extension. They form, and are exhumed, through relatively fast transport of middle and lower continental crust to the Earth's surface...
es, the 'type example' of which is defined by the Whipple Mountains
Whipple Mountains
The Whipple Mountains, 'Avii Kur'utat in the Mojave language, are located in eastern San Bernardino County, California. They are directly west of the Colorado River, Parker Dam, and Lake Havasu; south of Needles, California; north of Parker, Arizona and Vidal, California; and northeast of Vidal...
in southeastern California.
Geology
The Maria fold-and-thrust-belt is defined as the region where the compression that helped create the North American Cordillera – abruptly changed directions. North of the Maria fold-and-thrust-belt, the mountain ranges trend north-south, with east-west compression due to the subductionSubduction
In geology, subduction is the process that takes place at convergent boundaries by which one tectonic plate moves under another tectonic plate, sinking into the Earth's mantle, as the plates converge. These 3D regions of mantle downwellings are known as "Subduction Zones"...
of the Farallon slab
Farallon Plate
The Farallon Plate was an ancient oceanic plate, which began subducting under the west coast of the North American Plate— then located in modern Utah— as Pangaea broke apart during the Jurassic Period...
beneath western North America. At the Maria fold-and-thrust-belt, compressional deformation shifts to being generally north-south, with the front of the mountain ranges being defined by a roughly east-west line. This line then shifts gently to the east-southeast, where the Cordilleran deformation diffuses into a broad shear zone
Shear zone
A shear zone is a very important structural discontinuity surface in the Earth's crust and upper mantle. It forms as a response to inhomogeneous deformation partitioning strain into planar or curviplanar high-strain zones. Intervening blocks stay relatively unaffected by the deformation...
in northeastern Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
.
Another notable feature that differentiates it from the rest of the Cordillera is that the deformation involves the rocks of the North American craton. Deformation in the remainder of the Cordillera only involves rocks that were part of the near-shore and offshore, sedimentary sequences.
Ecology
Since soils and climate differ across the Maria fold-and-thrust-belt, this regional geologic structure can be considered a "dividing line" for a number of flora and fauna species. For example, the species range of the endangered California Fan Palm, Washingtonia filiferaWashingtonia filifera
Washingtonia filifera , with the common names California Fan Palm , Desert Fan Palm, Cotton palm, and Arizona Fan Palm. It is a palm native to southwestern North America between an elevation range of , at seeps, desert bajadas, and springs where underground water is continuously available...
does not extend north of the Maria fold-and-thrust-belt, or more specifically the Turtle Mountains
Turtle Mountains (California)
The Turtle Mountains, and Amat 'Achii'ar in the Mojave language, are located in San Bernardino County, California, in the southeastern part of the state.-Geography:The Turtle Mountains are southeast of Needles, California, west off of U.S...
.
Ranges
The Maria fold-and-thrust-belt comprises a large number of ranges in the south-eastern MojaveMojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
and north-western Sonoran deserts, including the:
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Granite Wash Mountains The Granite Wash Mountains are a short, arid, low elevation mountain range of western-central Arizona, in the southeast of La Paz County. The range borders a slightly larger range southeast, the Little Harquahala Mountains; both ranges form a section on the same water divide between two desert washes... Harcuvar Mountains The Harcuvar Mountains are a narrow mountain range in western-central Arizona, USA. The range lies just east of the north-south Colorado River, and south of the east-west, west-flowing Bill Williams River, from Alamo Lake.... Harquahala Mountains The Harquahala Mountains are the highest mountain range in southwestern Arizona, USA and are located southwest of the towns of Aguila and Wenden. The name originated from a local Native American people "Aha qua hala" which meant "water there is high up". The range is oriented from northeast to... Little Harquahala Mountains The Little Harquahala Mountains are a small, arid, low elevation mountain range of western-central Arizona, in the southeast of La Paz County.... Little Maria Mountains The Little Maria Mountains are located in southeastern California in the United States. The range lies in a northwest-southeasterly direction east of the Palen Mountains and west of the Big Maria Mountains... |
McCoy Mountains The McCoy Mountains are located in southeastern California in the United States.-Geography:The range lies in a northwest-southeasterly direction east of the Palen Mountains and south of the Little Maria Mountains... Mesquite Mountains The Mesquite Mountains are a mountain range in eastern San Bernardino County, California, near the border with Nevada. They are north of Interstate 15 in California and southeast of Death Valley.-North Mesquite Mountains Wilderness Area:... Mule Mountains (California) The Mule Mountains of California are located in the southeastern part of the state in the United States. The range lies in a northeast-southwesterly direction south of the McCoy Mountains and west of the Palo Verde Valley and Colorado River. The mountain range is approximately long and is located... New Water Mountains The New Water Mountains is a mountain range in southwestern Arizona. The range is on the northern border of the Kofa National Wildlife Refuge as well as the northern Kofa Mountains.It is a northwest-southeast trending range, about 20 miles long... |
Palen Mountains The Palen Mountains are located in the southern Mojave Desert - northern Colorado Desert in eastern Riverside County, California, USA. The range lies southeast of the Coxcomb Mountains, and northeast of the Chuckwalla Mountains near Interstate 10.... Plomosa Mountains The Plomosa Mountains are a mountain range in La Paz County, Arizona, running generally south of Bouse, Arizona near the Arizona/California border. The maximum height of the range is 1791 feet .... Rawhide Mountains The Rawhide Mountains are a mountain range of western Arizona, in the southwest of Mohave County. It is part of a block of mountain ranges on the north of an insular region called the Maria fold and thrust belt, containing mountain ranges, valleys, and plains... Riverside Mountains The Riverside Mountains are a mountain range in Riverside County, California. The town of Vidal, California is located in the West Riverside Mountains.-Geography:The Riverside Mountains are in the Colorado Desert, in the Lower Colorado River Valley region... Whipple Mountains The Whipple Mountains, 'Avii Kur'utat in the Mojave language, are located in eastern San Bernardino County, California. They are directly west of the Colorado River, Parker Dam, and Lake Havasu; south of Needles, California; north of Parker, Arizona and Vidal, California; and northeast of Vidal... |
Regional landforms
List of some regional landforms. (The ~east-west Bill Williams RiverBill Williams River
The Bill Williams River is a river in western-central Arizona in Mohave County; the river proper is the northern border of La Paz County which it drains in the north, as well as areas of far western Yavapai County...
appears as part of the central and northern perimeter of the Maria fold-and-thrust-belt, approximately paralleling the Rawhide Mountains
Rawhide Mountains
The Rawhide Mountains are a mountain range of western Arizona, in the southwest of Mohave County. It is part of a block of mountain ranges on the north of an insular region called the Maria fold and thrust belt, containing mountain ranges, valleys, and plains...
, a slight northwest range on west end.)
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Chemehuevi Wash The Chemehuevi Wash is a large wash of northeast San Bernardino County in the southeast Mojave Desert. The wash enters the center-west bank of Lake Havasu on the California–Arizona border... Colorado River The Colorado River , is a river in the Southwestern United States and northwestern Mexico, approximately long, draining a part of the arid regions on the western slope of the Rocky Mountains. The watershed of the Colorado River covers in parts of seven U.S. states and two Mexican states... Colorado River Indian Reservation The Colorado River Indian Reservation is 189 miles west of Phoenix, Arizona, on highway 95. It lies in western La Paz County, Arizona, southeastern San Bernardino County, California, and northeastern Riverside County, California. It has a total land area of 432.22 sq mi , and most of it lies... Lake Havasu Lake Havasu is a large reservoir behind Parker Dam on the Colorado River, on the border between California and Arizona. Lake Havasu City sits on the lake's eastern shore. The lake has a capacity of . The concrete arch dam was built by the United States Bureau of Reclamation between 1934 and 1938... La Posa Plain The La Posa Plain is a wide, generally flat plain in western Arizona near the Colorado River and is on the west and northwest border of the Kofa National Wildlife Refuge. The plain lies to the east of the Colorado River Indian Reservation and east of the Dome Rock and Trigo Mountains. Quartzsite,... |
Lower Colorado River Valley The Lower Colorado River Valley is the river region of the lower Colorado River of the southwestern United States in North America that rises in the Rocky Mountains and has its outlet at the Colorado River Delta in the northern Sea of Cortez in northwestern Mexico, between the states of Baja... Vidal Valley Vidal Valley is a 20 mile long valley in the far eastern Colorado Desert bordering the Colorado River. Most of the valley is in eastern San Bernardino County, California, but the outfall on the Colorado is in northeast Riverside County... |
See also
- List of mountain ranges of Arizona
- List of mountain ranges of California
- List of mountain ranges of the Lower Colorado River Valley
External links
- Maria Fold and Thrust Belt, University of Colorado Western US Tectonics Course