Maria fold and thrust belt

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Maria Fold-and-Thrust-Belt
Ranges, Plains & Thrusted Forms
Country United States
States California, Arizona
Regions Mojave Desert-NW—Sonoran Desert-SE
Counties San Bernardino County-CA
Mohave County-AZ-(N)
La Paz County-AZ-(S)
Municipalities Lake Havasu CityParker-AZ
Vidal JunctionBlythe-CA
Quartzsite-AZ
Borders on Mojave Desert-Colorado Desert-W
Mojave Desert-AZ-(north)
Sonoran Desert-AZ-(east)
Lake Lake Havasu
River Chemehuevi Wash-CA-(n-west perimeter)
Colorado River-(N-S)
Bill Williams River-(E-W, (tributary))
Length 65 mi (105 km), NW-SE
Width 45 mi (72 km)

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.[1] 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 complexes, the 'type example' of which is defined by the Whipple Mountains in southeastern California.

Geology[edit]

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[edit]

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.[2]

Ranges[edit]

The Maria fold-and-thrust-belt comprises a large number of ranges in the south-eastern Mojave and north-western Sonoran deserts,[3] including the:

Regional landforms[edit]

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.)

See also[edit]

References[edit]

  1. ^ Knapp, J. H.; Heizler, M. T. (1990). "Thermal History of Crystalline Nappes of the Maria Fold and Thrust Belt, West Central Arizona". Journal of Geophysical Research (American Geophysical Union) 95 (B12): 20,049–20,073. 
  2. ^ C. Michael Hogan. 2009. California Fan Palm: Washingtonia filifera, GlobalTwitcher.com, ed. Nicklas Stromberg
  3. ^ Spencer, Jon; Reynolds, S. J. (1990). "Relationship between Mesozoic and Cenozoic tectonic features in west-central Arizona and adjacent southeastern California". Journal of Geophysical Research 95 (B1): 539–555. Bibcode:1990JGR....95..539S. doi:10.1029/JB095iB01p00539. 

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