Late Precambrian U-Pb ages for the Brookville Gneiss, southern New Brunswick
- Geological Survey of Canada, Ottawa, Ontario (Canada)
Tonalitic orthogneiss from the Brookville Gneiss in southern New Brunswick has an igneous protolith age of 605 {plus minus} 3 Ma based on U-Pb dating of zircon. Metamorphic titanite from the same sample gives a minimum age of 564 {plus minus} 6 Ma for upper amphibolite facies metamorphism of the unit. Based on U-Pb analyses of single detrital zircons, a maximum sedimentary protolith age of about 641 Ma is suggested for associated paragneiss. These ages indicate that the igneous protolith of the orthogneiss was at most 35 Ma younger than the sedimentary rocks it intruded, and that the Brookville Gneiss is younger than the Green Head Group to which it was previously considered basement. Both orthogneiss and paragneiss in the Brookville Gneiss contain Proterozoic and Archean detrital zircon grains, suggesting an old, heterogeneous continental source. Bevier, White, and Barr conclude that the Brookville Gneiss does not represent the basement to the Avalon Terrane.
- OSTI ID:
- 5598807
- Journal Information:
- Journal of Geology; (USA), Journal Name: Journal of Geology; (USA) Vol. 98:6; ISSN JGEOA; ISSN 0022-1376
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
580000* -- Geosciences
ACTINIDE ISOTOPES
AGE ESTIMATION
BASEMENT ROCK
CANADA
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FORMATIONS
GEOLOGIC HISTORY
GEOLOGY
GNEISSES
ISOTOPE DATING
ISOTOPE RATIO
ISOTOPES
LEAD ISOTOPES
METAMORPHIC ROCKS
METAMORPHISM
MINERALS
NEW BRUNSWICK
NORTH AMERICA
OXYGEN COMPOUNDS
PRECAMBRIAN ERA
ROCKS
SEDIMENTARY ROCKS
SILICATE MINERALS
SILICATES
SILICON COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
URANIUM ISOTOPES
ZIRCON
ZIRCONIUM COMPOUNDS
ZIRCONIUM SILICATES