Laramide Basement Deformation in the Rocky Mountain Foreland of the Western United States

Deformation processes in brittle deformation zones in granitic basement rocks: A case study from the Torrey Creek area, Wind River Mountains
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Published:January 01, 1993
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CiteCitation
Gautam Mitra, 1993. "Deformation processes in brittle deformation zones in granitic basement rocks: A case study from the Torrey Creek area, Wind River Mountains", Laramide Basement Deformation in the Rocky Mountain Foreland of the Western United States, Christopher J. Schmidt, Ronald B. Chase, Eric A. Erslev
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The Wind River Mountain Range is one of the most prominent Laramide uplifts of the Rocky Mountains deformed foreland. Precambrian rocks in the core of the Wind River anticline were deformed inhomogeneously along a three-dimensional network of brittle and brittle-ductile deformation zones, which are present at all scales, allowing shortening of the basement core by an amount equivalent to that of the Phanerozoic cover. Along the northeast flank of the anticline where the cover sequence was thin (< 5 km), the underlying basement was deformed under brittle conditions, forming an anastomosing network of brittle deformation zones. The Torrey Creek zone is one such large brittle zone that is well exposed. It probably grew into a major zone because of its location between two different lithologies. Shearing within the zone occurred by distributed slip on numerous gently-dipping conjugate fractures with unidirectional slip. The zone has a complex deformation history of successive phases of shearing (involving grain-size reduction by stable and unstable fracturing, gouging, and wear) and dilation (involving vein precipitation) that allowed it to grow in thickness with increasing displacement. Both the development of and sliding on a network of such deformation zones require a significant amount of energy, and are important components of the total deformation in the Wind River Mountains.
- anticlines
- basement
- brittle deformation
- case studies
- deformation
- dilation
- displacements
- ductile deformation
- equations
- evolution
- folds
- fractures
- gouge
- granites
- igneous rocks
- Laramide Orogeny
- North America
- North American Cordillera
- plutonic rocks
- precipitation
- processes
- Rocky Mountains
- Rocky Mountains foreland
- thickness
- U. S. Rocky Mountains
- United States
- veins
- Wind River Range
- Wyoming
- Torrey Creek