U–Pb ages and Sm–Nd signature of two subsurface granites from the Fort Simpson magnetic high, northwest Canada

Autor:	R. J. Thériault, G. M. Ross, M. E. Villeneuve
Rok vydání:	1991
Předmět:	Basement (geology) Proterozoic Lithosphere Magmatism Geochronology Geochemistry engineering General Earth and Planetary Sciences engineering.material Biotite Isotopic composition Geology Zircon
Zdroj:	Canadian Journal of Earth Sciences. 28:1003-1008
ISSN:	1480-3313 0008-4077
Popis:	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 εNd of +1.3 and a TDM of 2.14 Ga, whereas the other yielded an initial εNd of −2.1 and a TDM 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.
Databáze:	OpenAIRE
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