U–Pb ages and Sm–Nd signature of two subsurface granites from the Fort Simpson magnetic high, northwest Canada
Two undeformed biotite granites recovered from exploratory hydrocarbon drill holes that penetrated basement in the Fort Simpson magnetic high were analyzed for U–Pb zircon geochronology and Sm–Nd isotopic composition. Both samples give crystallization ages of 1845 Ma, with errors of less than 5 Ma....
| Published in: | Canadian Journal of Earth Sciences |
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| Main Authors: | , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Canadian Science Publishing
1991
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| Subjects: | |
| Online Access: | http://dx.doi.org/10.1139/e91-091 http://www.nrcresearchpress.com/doi/pdf/10.1139/e91-091 |
| Summary: | Two undeformed biotite granites recovered from exploratory hydrocarbon drill holes that penetrated basement in the Fort Simpson magnetic high were analyzed for U–Pb zircon geochronology and Sm–Nd isotopic composition. Both samples give crystallization ages of 1845 Ma, with errors of less than 5 Ma. This age overlaps with the waning stages of magmatism in the Great Bear magmatic zone of Wopmay Orogen, 200 km to the east. One sample has an initial ε Nd of +1.3 and a T DM of 2.14 Ga, whereas the other yielded an initial ε Nd of −2.1 and a T DM of 2.45 Ga. The latter sample indicates that Early Proterozoic light rare-earth element enriched lithosphere with a crustal history dating back to at least 2.45 Ga is present in the subsurface west of Wopmay Orogen. |
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