Maria fold and thrust belt
{{Short description|Geologic feature in California and Arizona}}
{{Infobox landform
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| name = Maria Fold-and-Thrust-Belt
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| type = Fault system
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| location = San Bernardino County-CA
Mohave County-AZ-(N)
La Paz County-AZ-(S), Mojave Desert-NW—Sonoran Desert-SE, California, United States
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| length = ~{{convert|160|km|mi|abbr=on}}
(post-Basin & Range ext.)
| width = ~{{convert|60|km|mi|abbr=on}}
(post-Basin & Range ext.)
| area = ~{{convert|10000|km2|mi2|abbr=on}}{{cite journal|doi=10.1029/JB095iB01p00539|last=Spencer|first=Jon|author2=Reynolds, S. J.|year=1990|title=Relationship between Mesozoic and Cenozoic tectonic features in west-central Arizona and adjacent southeastern California|journal=Journal of Geophysical Research|volume=95|issue=B1|pages=539–555|bibcode=1990JGR....95..539S}}
(post-Basin & Range extension)
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| orogeny = Laramide
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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.{{cite journal|last=Knapp|first=J. H.|author2=Heizler, M. T.|year=1990|title=Thermal History of Crystalline Nappes of the Maria Fold and Thrust Belt, West Central Arizona|journal=Journal of Geophysical Research|publisher=American Geophysical Union|volume=95|issue=B12|pages=20,049–20,073|doi=10.1029/jb095ib12p20049|bibcode=1990JGR....9520049K}} Many of the deep structures of the MFTB have been exposed due to east–west to northeast-southwest Cenozoic age extension and unroofing.
In some parts of this fold-and-thrust-belt region, the extension resulted in the emplacement of metamorphic core complexes, the 'type example' of which is defined by the Whipple Mountains 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 subduction 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.
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 filifera does not extend north of the Maria fold-and-thrust-belt, or more specifically the Turtle Mountains.C. Michael Hogan. 2009. [http://globaltwitcher.auderis.se/artspec_information.asp?thingid=90942 California Fan Palm: Washingtonia filifera, GlobalTwitcher.com, ed. Nicklas Stromberg] {{webarchive|url=https://web.archive.org/web/20090930184850/http://globaltwitcher.auderis.se/artspec_information.asp?thingid=90942 |date=2009-09-30 }}
Ranges
The Maria fold-and-thrust-belt comprises a large number of ranges in the south-eastern Mojave and north-western Sonoran deserts, including the:
| * Big Horn Mountains
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Regional landforms
List of some regional landforms. (The ~east-west Bill Williams River 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.)
| * Alamo Lake State Park
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See also
References
{{reflist}}
{{Coord|33.8984|-114.5923|display=title}}
{{commons category|Maria fold and thrust belt}}
External links
- [http://www.colorado.edu/GeolSci/Resources/WUSTectonics/MariaFoldThrust/index.html Maria Fold and Thrust Belt], University of Colorado [http://www.colorado.edu/GeolSci/Resources/WUSTectonics/tectonics.html Western US Tectonics Course]
{{California Faults}}
Category:Geology of California
Category:Basin and Range Province
Category:North American Cordillera
Category:Geography of Imperial County, California
Category:Geography of San Bernardino County, California