Abstract
Removal of the Mid-Cretaceous Idaho Batholith by the crustal-scale, western Idaho shear zone
Abstracts with programs - Geological Society of America, Vol.35(6), p.473
Geological Society of America, 2003 annual meeting
11/2003
Abstract
During the Mid-Cretaceous, abundant plutonism occurred in the Western United States. This plutonism was a result of rapid subduction on the western margin of North America. Voluminous Mid-Cretaceous plutonism is found in all coastal batholiths, including the Peninsular Range, the Sierra Nevada, and the Coast Range plutonic complexes, where the Mid-Cretaceous sections of these arcs are approximately 40-60 km wide. In contrast, Mid-Cretaceous plutonism in the Idaho Batholith occurs in a 10 km wide zone on the batholith's western edge. Our work suggests that a approximately 50-60 km wide, Mid-Cretaceous arc existed in the Idaho Batholith, but has been structurally thinned. Mid-Cretaceous plutons along the western edge of the Idaho Batholith are generally deformed by the western Idaho shear zone, which was active during the Late Cretaceous. Fabric in this zone displays sub-vertical, NS-oriented foliation and sub-vertical lineation. Finite strain and vorticity analysis indicates that deformation in the western Idaho shear zone was characterized by dextral transpression, with large amounts of vertical extrusion, which explains the exhumation of approximately 7 kbar granitic rocks. Deformation within the western Idaho shear zone resulted in a minimum of approximately 10 km of right-lateral offset and 40-50 km of east-west shortening. Restoration of this contractional deformation yields an initial width of 50-60 km for the zone of Mid-Cretaceous plutonism, and the highly elongate plutonic bodies are restored to approximately equant horizontal dimensions. This restoration results in a series of Mid-Cretaceous batholiths, of relatively constant width, within the North American Cordillera.
Details
- Title: Subtitle
- Removal of the Mid-Cretaceous Idaho Batholith by the crustal-scale, western Idaho shear zone
- Creators
- Scott Giorgis - University of Wisconsin at Madison, Geology and Geophysics Madison, WI USA United StatesBasil TikoffWilliam C McClelland
- Resource Type
- Abstract
- Publication Details
- Abstracts with programs - Geological Society of America, Vol.35(6), p.473
- Conference
- Geological Society of America, 2003 annual meeting
- Publisher
- Geological Society of America (GSA)
- ISSN
- 0016-7592
- Alternative title
- Geological Society of America, 2003 annual meeting
- Language
- English
- Date published
- 11/2003
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984240890202771
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