Journal article
Insights into the metamorphic evolution of the Belt-Purcell basin;; evidence from Lu-Hf garnet geochronology
Canadian journal of earth sciences, Vol.47(2), pp.161-179
02/2010
DOI: 10.1139/E10-001
Abstract
We have determined Lu-Hf garnet ages from spatially separated garnet bearing localities in northern Idaho. The Lu-Hf ages are diverse and reflect a progression of Mesoproterozoic metamorphic events. The oldest Lu-Hf garnet age determined in this study is 1463 ± 24 Ma for garnet within a kyanite schist exposed in the core-zone of the Boehls Butte metamorphic complex. A garnet schist from the Priest River complex yields a well-defined age of 1379 ± 8 Ma. A garnet-staurolite schist, a garnet-mica schist, and a gem-grade Idaho star garnet sample all from the general vicinity of Clarkia, Idaho, yield ages of 1064 ± 10, 1081 ± 20, and 1078 ± 17 Ma, respectively. A garnet amphibolite, also collected from the Boehls Butte metamorphic complex, yields an age of 1151 ± 41 Ma for garnet porphyroblasts and 137 ± 25 Ma for diffuse overgrowths. The Hf in all of the Proterozoic garnets is extraordinarily radiogenic with εHf values ranging from +1210 to +10546, which attest to both their high Lu/Hf ratios and their great antiquity. All of the samples analyzed in this study are from the rocks of the Mesoproterozoic Belt-Purcell Supergroup or its basement. These data provide evidence of polymetamorphism in northwestern Laurentia during the Mesoproterozoic.
Details
- Title: Subtitle
- Insights into the metamorphic evolution of the Belt-Purcell basin;; evidence from Lu-Hf garnet geochronology
- Creators
- N. A Zirakparvar - Syracuse UniversityJ. D Vervoort - School of Earth and Environmental Sciences, WA State University, Pullman, WA 99164, USA.W McClelland - University of IowaR. S Lewis - University of Idaho
- Resource Type
- Journal article
- Publication Details
- Canadian journal of earth sciences, Vol.47(2), pp.161-179
- DOI
- 10.1139/E10-001
- ISSN
- 0008-4077
- eISSN
- 1480-3313
- Language
- English
- Date published
- 02/2010
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229307302771
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