Journal article
Missing Idaho arc; transpressional modification of the 87Sr/86Sr transition on the western edge of the Idaho Batholith
Geology (Boulder), Vol.33(6), pp.469-472
06/2005
DOI: 10.1130/G20911.1
Abstract
The North American Cordillera is characterized by subduction-related Mesozoic batholiths with voluminous Middle Cretaceous plutonism. In the Cordillera, the Idaho Batholith is anomalous, containing only a narrow (<10 km) band of Middle Cretaceous plutons on its extreme western margin. These plutons are spatially coincident with the Late Cretaceous, crustal-scale, dextral transpressional western Idaho shear zone. Finite strain analysis indicates that there is significant east-west shortening in the western Idaho shear zone. A reconstruction using isotopic variations as strain markers, and comparing them to the undeformed Middle Cretaceous Sierra Nevada Batholith, results in a Middle Cretaceous magmatic arc in western Idaho similar in width (∼85- 100 km) to other sections of the Cordilleran magmatic arc. The tectonic implications include: (1) a full magmatic arc existed in Idaho in the Middle Cretaceous prior to Late Cretaceous deformation; (2) the currently sharp 87Sr/86Sr transition in western Idaho represents structural modification of the batholith after emplacement (i.e., the steep isotopic gradient results from deformation); and (3) as a result of Late Cretaceous shortening in the western Idaho shear zone, the main part of the Idaho Batholith (i.e., post-ca. 90 Ma) intruded farther eastward into thick North American lithosphere. Consequently, the main part of the Idaho Batholith has a stronger continental signature than the other coastal batholiths.
Details
- Title: Subtitle
- Missing Idaho arc; transpressional modification of the 87Sr/86Sr transition on the western edge of the Idaho Batholith
- Creators
- Scott Giorgis - University of Wisconsin–MadisonBasil Tikoff - University of Wisconsin–MadisonWilliam McClelland - University of Idaho
- Resource Type
- Journal article
- Publication Details
- Geology (Boulder), Vol.33(6), pp.469-472
- Publisher
- Geological Society of America (GSA)
- DOI
- 10.1130/G20911.1
- ISSN
- 0091-7613
- eISSN
- 1943-2682
- Language
- English
- Date published
- 06/2005
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229172302771
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