New UPb age constraints on latest Cretaceous magmatism and associated mineralization in the Fawnie Range, Nechako Plateau, central British Columbia

Friedman, Richard M.; Diakow, Larry J.; Lane, R. A.; Mortensen, James K.

doi:10.1139/e00-122

Cited by 8 publications

(7 citation statements)

References 25 publications

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“…The Late Jurassic Laidman pluton intrudes rocks of the Hazelton and Bowser Lake groups in the Fawnie Range (Diakow and Levson 1997;Friedman et al 2001).…”

Section: Stikine Terrane (Stikinia)mentioning

confidence: 98%

Lithostratigraphic and tectonic framework of Jurassic and Cretaceous Intermontane sedimentary basins of south-central British Columbia¹This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.

Riddell

2011

Can. J. Earth Sci.

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The south-central Intermontane belt of British Columbia has a complex architecture comprising late Paleozoic to Mesozoic volcanic and plutonic arc magmatic suites, marine and nonmarine clastic basins, high-grade metamorphic complexes, and accretionary rocks. Jurassic and Cretaceous clastic basins within this framework contain stratigraphy with hydrocarbon potential. The geology is complicated by Cretaceous to Eocene deformation, dismemberment, and dislocation. The Eocene to Neogene history of the southern Intermontane belt is dominated by non-arc volcanism, followed by Pleistocene to Recent glaciation. The volcanic and glacial cover makes this a difficult region to explore for resources. Much recent work has involved re-evaluating the challenges that the overlying volcanic cover has historically presented to geophysical imaging of the sedimentary rocks in this region in light of technological advances in geophysical data collection and analysis. This paper summarizes the lithological and stratigraphic framework of the region, with emphasis on description of the sedimentary units that have been the targets of hydrocarbon exploration.Résumé : La ceinture intermontagneuse du centre-sud de la Colombie-Britannique a une architecture complexe (Paléozoïque à Mésozoïque) comprenant des suites magmatiques, volcaniques et d'arcs plutoniques, des bassins clastiques marins et non marins, des complexes à métamorphisme élevé et des roches d'accrétion. Les bassins clastiques du Jurassique et du Crétacé dans ce cadre comprennent une stratigraphie à potentiel d'hydrocarbures. La géologie a été rendue complexe par des défor-mations, des démembrements et des dislocations du Crétacé à l'Éocène. L'historique de l'Éocène au Néogène de la ceinture intermontagneuse sud est dominé par un volcanisme ne provenant pas d'arcs, suivi d'une glaciation du Pléistocène au Ré-cent. La couverture volcanique et glaciaire de la région complique l'exploration pour des ressources. Étant donné les progrès technologiques dans la collecte et l'analyse de données géophysiques, une grande partie des travaux récents comprenaient la réévaluation des défis que présentait historiquement la couverture volcanique à obtenir une imagerie géophysique des roches sédimentaires de la région. Le présent article résume le cadre lithologique et stratigraphique de la région, mettant l'accent sur la description des unités sédimentaires qui ont été ciblées pour la recherche d'hydrocarbures.[Traduit par la Rédaction]

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“…The Late Jurassic Laidman pluton intrudes rocks of the Hazelton and Bowser Lake groups in the Fawnie Range (Diakow and Levson 1997;Friedman et al 2001).…”

Section: Stikine Terrane (Stikinia)mentioning

confidence: 98%

Lithostratigraphic and tectonic framework of Jurassic and Cretaceous Intermontane sedimentary basins of south-central British Columbia¹This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.

Riddell

2011

Can. J. Earth Sci.

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“…In the central part of the belt, the Lower to Middle Jurassic Hazelton Group is exhumed in horsts of the Nechako and Fawnie ranges, where it is overlain by Middle to Upper Jurassic rocks of the Bowser Lake Group, which includes transitional deep to shallow-water sedimentary successions (Diakow et al 1997). These Hazelton and Bowser Lake rocks are intruded by Late Jurassic plutons (Friedman et al 2001).…”

Section: South-central Intermontane Beltmentioning

confidence: 99%

Deep seismic reflection constraints on Paleogene crustal extension in the south-central Intermontane belt, British Columbia

Calvert

Talinga

2014

Can. J. Earth Sci.

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Following growth of the Canadian Cordillera during the Mesozoic, the southern Cordillera was subject to extension during the Paleocene and Eocene that correlated with widespread volcanic activity in south-central British Columbia, including across much of the Nechako-Chilcotin plateau. In 2008, Geoscience BC acquired 330 km of deep vibroseis reflection profiles on the plateau, mostly over the Stikinia arc terrane, but also over its eastern contact with the oceanic Cache Creek terrane. All seven seismic reflection lines reveal a strongly reflective lower crust that extends from 7 to 9 s down to the Moho, which is defined by the downward termination of reflectivity at 11-12 s. In the uppermost crust, extension occurred by block faulting with faults soling into subhorizontal to shallowly dipping detachments above 10 km depth. Extension in the deeper upper and middle crust, which was partly controlled by antiforms likely related to earlier shortening, was accommodated on a network of anastomosing shear zones that sole out into the top of the reflective lower crust. The lower crustal reflections correlate with seismic P-wave velocities of 6.45-6.98 km/s, indicating that the reflective lower crust has a more mafic composition than the middle crust. As in other extensional settings, we suggest that this pervasive fabric of reflectors arises from the intrusion of mantle-derived basaltic magma into zones of ductile shearing, and that differentiation of these melts resulted in the widespread Paleocene to Eocene volcanism. Reflector dips indicate that extension was approximately east-west, consistent with north-northwest-trending horsts separated by basins filled with Paleocene to Eocene volcanic and volcaniclastic rocks.Résumé : Après la croissance de la Cordillère canadienne au Mésozoïque, la Cordillère sud a subi une extension durant le Paléocène et l'Éocène; cette extension était corrélée avec une activité volcanique étendue dans le centre-sud de la ColombieBritannique, incluant à travers une grande partie du plateau Nechako-Chilcotin. En 2008, Geoscience BC a acquis 330 km de profiles vibrosismiques en profondeur sur le plateau, surtout au-dessus du terrane d'arc de Stikinia mais aussi par-dessus son contact est avec le terrane océanique de Cache Creek. Les sept lignes de sismique réflexion révèlent toutes une croûte inférieure fortement réflective qui s'étend depuis 7-9 s jusqu'au Moho, ce qui est défini par la terminaison vers le bas de la réflectivité à 11-12 s. Dans la croûte sommitale, l'extension s'est produite par le morcellement en bloc par des failles; les failles formant une semelle dans les détachements subhorizontaux ou avec un léger pendage, au-dessus de la profondeur de 10 km. L'extension dans les croûtes supérieure et médiane, plus profondes, partiellement contrôlée par des antiformes fort probablement reliés à un rétrécissement antérieur, était facilitée par un réseau de zones de cisaillement anastomosées qui forment une semelle sur le dessus de la couche inférieure réfléchissante. Les réflexions de la ...

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“…The timing of magmatism and mineralization at these three deposits is similar (72 to 67 Ma), suggesting a pulse of transpression-related magmatism and mineralization in this region in the Late Cretaceous (Andrew 1988;Lane and Schroeter 1997;Friedman et al 2001;Christie et al 2014).…”

Section: Ore Depositional Processesmentioning

confidence: 86%

Geochemistry, geochronology, and fluid inclusion study of the Late Cretaceous Newton epithermal gold deposit, British Columbia

et al. 2016

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Newton is an intermediate-sulfidation epithermal gold deposit related to Late Cretaceous continental-arc magmatism in south-central British Columbia. Disseminated gold mineralization occurs in quartz–sericite-altered Late Cretaceous felsic volcanic rocks, and feldspar–quartz–hornblende porphyry and quartz–feldspar porphyry intrusions. The mineralization can be divided into three stages: (1) disseminated pyrite with microscopic gold inclusions, and sparse quartz–pyrite ± molybdenite veins; (2) disseminated marcasite with microscopic gold inclusions and minor base-metal sulfides; and (3) polymetallic veins of pyrite–chalcopyrite–sphalerite–arsenopyrite. Re–Os dating of molybdenite from a stage 1 vein yielded an age of 72.1 ± 0.3 Ma (published by McClenaghan in 2013). The age of the host rocks has been constrained by U–Pb dating of zircon: Late Cretaceous felsic volcanic rocks, 72.1 ± 0.6 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013); feldspar–quartz–hornblende porphyry, 72.1 ± 0.5 Ma; quartz–feldspar porphyry, 70.9 ± 0.5 Ma (Amarc Resources Ltd., unpublished data, reported by McClenaghan in 2013). The mineralized rocks are intruded by a barren diorite, with an age of 69.3 ± 0.4 Ma. Fluid inclusions in quartz–pyrite ± molybdenite ± gold veins yielded an average homogenization temperature of 313 ± 51 °C (number of samples, n = 82) and salinity of 4.8 ± 0.9 wt.% NaCl equiv. (n = 46), suggesting that a relatively hot and saline fluid likely of magmatic origin was responsible for the first stage of mineralization. Some evidence for boiling was also observed in the veins. However, the bulk of the gold mineralization occurs as disseminations in the wall rocks, suggesting that wall-rock reactions were the main control on ore deposition.

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New UPb age constraints on latest Cretaceous magmatism and associated mineralization in the Fawnie Range, Nechako Plateau, central British Columbia

Cited by 8 publications

References 25 publications

Deep seismic reflection constraints on Paleogene crustal extension in the south-central Intermontane belt, British Columbia

Geochemistry, geochronology, and fluid inclusion study of the Late Cretaceous Newton epithermal gold deposit, British Columbia

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New UPb age constraints on latest Cretaceous magmatism and associated mineralization in the Fawnie Range, Nechako Plateau, central British Columbia

Cited by 8 publications

References 25 publications

Deep seismic reflection constraints on Paleogene crustal extension in the south-central Intermontane belt, British Columbia

Geochemistry, geochronology, and fluid inclusion study of the Late Cretaceous Newton epithermal gold deposit, British Columbia

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New UPb age constraints on latest Cretaceous magmatism and associated mineralization in the Fawnie Range, Nechako Plateau, central British Columbia