William A. Rehrig, 1996. "A Field Trip Overview to Low-Angle Faults and Associated Mineralization", Tertiary Extension and Mineral Deposits, Southwestern U.S., William A. Rehrig, James J. Hardy
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The Cordillera of western North America may succinctly be described as an accreted continental margin consisting of obducted and stacked oceanic and miogeoclinal plates (Late Precambrian to Mesozoic), which has been overprinted by extraordinary Tertiary extension, particularly in middle North American. Both compressional and extensional processes have utilized gently dipping (low-angle) structural features, which include thrust faults, detachment faults, and rotated or listric normal faults. The thrusts commonly are mylonitic, indicating ductile shear at some depth. The detachments are marked by mylonitic and later brecciated footwall fabrics, suggesting deep and shallow deformation.
Such low-angle zones of shear, while not unique to the southwestern United States, are especially well exposed there. On this field trip we will have the pleasure of viewing key outcrops over a broad region of southern Nevada and western Arizona. These exposures are particularly instructive not only as examples of unique tectonic processes, but also with regard to mineral deposits hosted by such low-angle faults.