Eocene Stratigraphy, Age of the Coryell Batholith, and Extensional Faults in the Granby Valley, southern British Columbia

Carr, Sharon D.; Parkinson, Donald

doi:10.4095/127450

Cited by 10 publications

(7 citation statements)

References 0 publications

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“…The low-angle normal fault strikes north to north-northeast, and from its trace across topography in the map area, dips 30°to the west (Fig. 2), consistent with the 25°-35°dip reported by Carr and Parkinson (1989) <10 km north of study area.…”

Section: The Granby Faultsupporting

confidence: 87%

“…The Coryell intrusive suite, which borders the complex in the map area, yields a crystallization age of 51.1 ± 0.5 Ma (Carr and Parkinson 1989). Thus, it seems likely that generation 5 monazite is related to either or both of thermal or hydrothermal processes concomitant with the intrusion of the nearby Coryell batholith.…”

Section: Generationmentioning

confidence: 96%

“…This would require at least 4-6 vertical km of west-side-down slip on the Granby fault near Grand Forks. The Coryell syenite is, in part, cut by the Granby fault, constraining the latest movement to be post 51.1 ± 0.5 Ma (Carr and Parkinson 1989) (Table 1; Fig. 1b).…”

Section: The Granby Faultmentioning

confidence: 98%

“…1). Although originally mapped as steeply dipping (Preto 1970), Carr and Parkinson (1989) locally estimated the dip of the fault at 25°-35°. A portion of the Granby fault is well exposed in the Volcanic Creek area, 15 km north of the town of Grand Forks in south-central British Columbia, near the Canada -United States border (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Geology of the western margin of the Grand Forks complex, southern British Columbia: high-grade Cretaceous metamorphism followed by early Tertiary extension on the Granby fault

Laberge¹,

Pattison²

2007

Can. J. Earth Sci.

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The Grand Forks complex, in the southern Omineca belt of British Columbia, is a fault-bounded tectonic window exposing Proterozoic sediments and associated mafic rocks metamorphosed to upper amphibolite to granulite facies. Its western margin is marked by the Granby fault, an Eocene west-dipping, low-angle, normal fault characterized by brittle deformation. The metasediments of the Grand Forks complex consist of migmatitic paragneiss containing a peak metamorphic assemblage of garnet + cordierite + sillimanite + K-feldspar ± biotite + quartz. Pressure-temperature conditions for this assemblage are 800 ± 35°C and 5.8 ± 0.6 kbar (1 kbar = 100 MPa). Resorption of garnet to cordierite ± spinel suggests nearly isothermal decompression of about 2 kbar from peak conditions, interpreted to have occurred prior to normal displacement on the Granby fault. Laser ablation U-Pb dating of monazite from the metasediments suggests a dominant episode of Late Cretaceous metamorphism at 84 ± 3 Ma, with evidence for earlier episodes of Cretaceous metamorphism at 119 ± 3 and 104 ± 3 Ma. Early Tertiary recrystallization at 51 ± 2 Ma is coeval with the emplacement of the nearby Coryell plutonic suite. In the hanging wall of the Granby fault, allochthonous sedimentary and volcanic rocks of Quesnel terrane contain mineral assemblages indicative of the upper greenschist to lower amphibolite facies. Pressure-temperature conditions are estimated at 425 ± 40°C and 2.3 ± 0.7 kbar. The throw (vertical displacement) on the Eocene Granby fault is estimated to be on the order of 5 km. While significant, the fault cannot account for the entire amount of tectonic uplift of the core complex.Résumé : Le complexe métamorphique de Grand Forks est une fenêtre tectonique, bordée de failles normales, qui expose des roches de la croûte moyenne dans la ceinture d'Omineca, en Colombie-Britannique. Sur sa marge occidentale, la faille éocène de Granby est une faille cassante à pendage modéré vers l'ouest. Le complexe métamorphique expose des migmatites au faciès des granulites, localement caractérisés par l'assemblage minéralogique grenat + cordiérite + sillimanite + feldspath potassique ± biotite + quartz, dérivées de sédiments protérozo|que. Les conditions de pression-température maximum sont estimées à 800 ± 35°C et 5,8 ± 0,6 kbar (1 kbar = 100 MPa). Une texture de résorption du grenat en cordiérite suggère un épisode de décompression quasi-isothermique, précédant le déplacement sur la faille de Granby. La datation U-Pb par ablation au laser sur monazite démontre une période de métamorphisme régional au Crétacé tardif à 84 ± 3 Ma. Des évènements métamorphiques sont aussi datés à 119 ± 3 et 104 ± 3 Ma. Une recrystallisation éocene de la monazite (51 ± 2 Ma) est concomitante avec l'intrusion du batholithe de Coryell. Dans le toit de la faille de Granby, les roches sédimentaires et volcaniques allochtones du terrane de Quesnel contiennent des assemblages minéralogiques caractéristiques de la transition entre le faciès supérieur des schistes verts au faciès infé...

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Section: The Granby Faultsupporting

confidence: 87%

Section: Generationmentioning

confidence: 96%

Section: The Granby Faultmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

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Geology of the western margin of the Grand Forks complex, southern British Columbia: high-grade Cretaceous metamorphism followed by early Tertiary extension on the Granby fault

Laberge¹,

Pattison²

2007

Can. J. Earth Sci.

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show abstract

“…Sheppard considered by Little (1982) to be a part of Coryell plutonic rocks. Zircon uranium-lead age of Coryell plutonic rocks is 51 Ma (Carr and Parkinson, 1989). Biotite potassium-argon age is 52 Ma (Yates and Engels, 1968, recalculated using current IUGS constants, Steiger and Jaeger, 1977) Ksm Sophie Mountain Formation (Cretaceous)-Conglomerate with minor sandstone.…”

Section: Tcsmentioning

confidence: 99%