Maria fold and thrust belt

Maria Fold-and-Thrust-Belt
Fault system
Location	San Bernardino County-CA Mohave County-AZ-(N) La Paz County-AZ-(S), Mojave Desert-NW—Sonoran Desert-SE, California, United States
Age	86.3±1.3 – ~55 Ma[2]
Orogeny	Laramide
Area
• Total	~10,000 km2 (3,900 sq mi)[1] (post-Basin & Range extension)
Dimensions
• Length	~160 km (99 mi) (post-Basin & Range ext.)
• Width	~60 km (37 mi) (post-Basin & Range ext.)

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.^[3] 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.