Thesis
Lu-Hf garnet geochronology of the Salmon River suture zone, west-central Idaho
Washington State University
Master of Science (MS), Washington State University
2012
Handle:
https://hdl.handle.net/2376/100289
Abstract
The Salmon River suture zone (SRSZ) in west-central Idaho chronicles the accretion of island arc terranes to North America. It is a broad north to northeast-striking belt (>25 km wide) of high strain which records Jurassic-Cretaceous island-arc to continent collision. Unique to this belt is a prominent change in the initial 87Sr/86Sr ratio and the narrowness of the zone in which this change occurs. Timing of the onset of deformation within the suture zone is not well established, primarily due to a weakly constrained metamorphic history. Existing garnet geochronology of a few units within the SRSZ, using the Sm-Nd isotope system, has provided a preliminary temporal framework for the progressive accretion of arc-derived rocks to North America, but this geochronology is limited in scope and extent. In this study, I report garnet Lu-Hf isotope dates from samples within the suture zone, along strike of the initial 87Sr/86Sr isopleth. These results have two important implications for the Mesozoic evolution of the western edge of North America. First, deformation on structures within the SRSZ occurred over a more than 30 million year time span in the mid-Cretaceous between ~122-90 Ma (this study). Second, these garnets grew simultaneously during a progressive history of contractional deformation and crustal thickening associated with cooling and uplift of rocks due to the accretion of island-arc terranes to North America.
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Details
- Title
- Lu-Hf garnet geochronology of the Salmon River suture zone, west-central Idaho
- Creators
- Diane Elaine Wilford
- Contributors
- Jeffrey D. Vervoort (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525168301842
- Language
- English
- Resource Type
- Thesis