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Stacey thesis final9.58 MB
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Thesis
ISOTOPE GEOCHEMISTRY OF THE GROUSE CREEK CRUSTAL PROVINCE AND ITS PLACE IN THE ASSEMBLY OF WESTERN LAURENTIA
Washington State University
Master of Science (MS), Washington State University
07/2024
DOI:
https://doi.org/10.7273/000007092
Abstract
Prior investigations of the Albion-Raft River-Grouse Creek metamorphic core complex, which straddles the border of northwest Utah and south-central Idaho, indicate that this part of the Great Basin is underlain by Archean rocks that have experienced a complex deformational history through at least the Miocene. These rocks represent one of the few surface exposures of Grouse Creek block basement. While previous work established the ancient character of these rocks, the affinity of this Archean crustal fragment and its relationship to neighboring cratons within western Laurentia remain undefined. A better understanding of the Archean paleogeography of western Laurentia would provide powerful constraints on the tectonic setting for the region.
This study presents new laser ablation-inductively coupled mass spectrometry U-Pb zircon geochronology and Lu-Hf zircon isotopic composition data from the Albion-Raft River-Grouse Creek metamorphic core complex that further characterize the Grouse Creek block. The protolith of a monzogranitic orthogneiss, which is exposed in all 3 ranges, intruded at ca. 2.57 Ga. Hafnium isotopes (negative εHf(t) values ranging from -7.6 to -1.7) imply that these rocks and a previously unmapped ca. 2.73 Ga orthogneiss (εHf(t): -6.9) were derived from reworked crustal material. Exposures of orthogneiss with ages similar to the ca. 2.57 Ga orthogneiss from the Albion-Raft River-Grouse Creek uplifts occur in other exposures within the Grouse Creek block and suggests that this intrusion represents a prominent event in the history of the province.
New dates from an older paragneiss unit indicate deposition no earlier than 2663 Ma in the Raft River Mountains and 2675 Ma in the Grouse Creek Mountains. Age spectra and Hf isotope results from these samples are consistent with a provenance in the Wyoming Craton to the east.
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Details
- Title
- ISOTOPE GEOCHEMISTRY OF THE GROUSE CREEK CRUSTAL PROVINCE AND ITS PLACE IN THE ASSEMBLY OF WESTERN LAURENTIA
- Creators
- Andrew Michael Stacey
- Contributors
- Jeffrey Vervoort (Chair)Johannes Haemmerli (Committee Member)Michael Wells (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- School of the Environment (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University
- Number of pages
- 155
- Identifiers
- 99901152438901842
- Language
- English
- Resource Type
- Thesis