Journal article
U-Pb geochronology of Late Cretaceous and early Tertiary plutons in the northern Coast Mountains Batholith
Canadian journal of earth sciences, Vol.28(6), pp.899-911
Geological Association of Canada--Mineralogical Association of Canada (GAC-MAC) annual general meeting, symposium on Geological transect: northwestern Canadian Cordillera
06/1991
DOI: 10.1139/e91-082
Abstract
U-Pb geochronological studies demonstrate that steeply dipping, sheetlike tonalitic plutons along the W margin of the N Coast Mountains batholith were emplaced between approx 83 and approx 57 (perhaps approx 55) m.y. Less elongate tonalitic- granodioritic bodies in central portions of the batholith yield ages of 59-58 m.y., coeval with younger phases of the tonalitic sheets. Large granite-granodiorite bodies in central and E portions of the batholith were emplaced at 51-48 m.y. Trends in ages suggest that the tonalitic bodies generally become younger southeastward and that, at the latitude of Juneau, plutonism migrated northeastward across the batholith at approx 0.9 km/m.y. Variations in the age, shape, location, and degree of fabric development among the various plutons indicate that late Cretaceous-Palaeocene tonalitic bodies were emplaced into a steeply dipping, dip-slip shear zone that was active along the western margin of the batholith. Postkinematic Eocene plutons were emplaced at shallow crustal levels. Inherited zircon components in these plutons range in age from mid-Palaeozoic to early Proterozoic and are coeval with detrital zircons in adjacent metasedimentary rocks. These old zircons, combined with evolved Nd isotopic signatures for most plutons, record assimilation of continental crustal or supracrustal rocks during the generation and/or ascent of the plutons. [Authors' abstract]
Details
- Title: Subtitle
- U-Pb geochronology of Late Cretaceous and early Tertiary plutons in the northern Coast Mountains Batholith
- Creators
- George E Gehrels - University of ArizonaWilliam C McClelland - University of ArizonaScott D Samson - University of ArizonaP. Jonathan Patchett - University of ArizonaDavid A Brew - University of Arizona
- Contributors
- R. G Anderson (Editor) - Geol. Surv. Can., Cordilleran Div. Vancouver, BC CAN Canada
- Resource Type
- Journal article
- Publication Details
- Canadian journal of earth sciences, Vol.28(6), pp.899-911
- Conference
- Geological Association of Canada--Mineralogical Association of Canada (GAC-MAC) annual general meeting, symposium on Geological transect: northwestern Canadian Cordillera
- Publisher
- National Research Council of Canada
- DOI
- 10.1139/e91-082
- ISSN
- 0008-4077
- eISSN
- 1480-3313
- Alternative title
- Contributions to the geology and geophysics of northwestern British Columbia and southeastern Alaska--Contributions a la geologie et a la geophysique du nord-ouest de la Colombie-Britannique et du sud-est de l'Alaska
- Language
- English; French
- Date published
- 06/1991
- Academic Unit
- Earth and Environmental Sciences
- Record Identifier
- 9984229178702771
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