U–Th–Pb geochronologic constraints on the structural evolution of the Selkirk fan, northern Selkirk Mountains, southern Canadian Cordillera

Gibson, H. Daniel; Brown, Richard L.; Carr, Sharon D.

doi:10.1016/j.jsg.2005.05.014

Cited by 24 publications

(31 citation statements)

References 59 publications

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“…By Late Jurassic time, some of these deeply buried rocks had been exhumed and carried northeastward as the retro-wedge expanded. The Jurassic, SW-vergent structures are preserved at high structural levels along the western margins of the Omineca Belt where their northeastern boundary delimits a local zone of structural divergence known as the Selkirk fan (Figs lb, 2 & 3;Wheeler 1963Wheeler , 1965Price & Mountjoy 1970;Brown & Tippett 1978;Brown et al 1993;Colpron et al 1998;Gibson et al 2005).…”

Section: Geological Settingmentioning

confidence: 99%

“…The lowest level exposures are of middle to lower crustal rocks coring domal metamorphic complexes that were deeply buried in the Palaeocene and rapidly exhumed in the Eocene (Parrish 1995). Structurally above and flanking these outward-dipping domal exposures are the midcrustal rocks within the Selkirk allochthon that were mobile and at high metamorphic grade through most of Cretaceous time (Gibson 2003;Gibson et aL 2005). The highest levels exposed within the Selkirk allochthon contain strata that were variably deformed and metamorphosed in the Middle Jurassic and exhumed to upper crustal Kretz (1983).…”

Section: The Cretaceous Mid-crustal Ductile Zonementioning

confidence: 99%

“…Sevigny et al 1990). Recent structural analysis and geochronology by Gibson et al (2004Gibson et al ( , 2005; see also Crowley et al 2000;Gibson, 2003) across the Big Bend area of the southern part of the hinterland, point to the existence of a middlecrustal zone some 10 to 20 km thick, which was at upper amphibolite facies from as early as Middle Jurassic time until exhumation in the Late Cretaceous. The upper and lower boundaries of this ductile zone exhibit structural and thermal gradients that support a channel flow model of midcrustal deformation.…”

mentioning

confidence: 96%

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An argument for channel flow in the southern Canadian Cordillera and comparison with Himalayan tectonics

Brown

Gibson

2006

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Crustal thickening in excess of 55 km, and high heat flow, suggest that a high-standing plateau region in the Cordilleran hinterland was present in the Late Cretaceous. A low strength middle crust developed beneath the plateau, and parts of this layer were exhumed to upper crustal levels in Late Cretaceous to Eocene time. During Late Cretaceous time, structures in the hinterland were reactivated. Strata, buried to mid-crustal depths since the Jurassic, began to flow upward to higher levels; earlier structures were refolded and tightened, and a new transposition fabric developed. Some 10-20 km of the middle crust was involved in high temperature ductile flow. The lower boundary of the ductile zone lies with thrust sense on top of Precambrian rocks of Canadian Shield affinity, and splays upwards to the NE where it closely coincides with highly strained rocks in the hanging wall of the Purcell Thrust Fault. The upper boundary is marked by a normal-sense high strain zone, above which only minor Cretaceous deformation occurred. The boundaries were reactivated at upper crustal levels after cessation of flow in the mid-crustal channel. This reactivation resulted in formation of ductile to brittle extension faults such as the Okanagan Fault System. During final stages of flow, the Precambrian basement gneisses at the base of the channel became domed and exhumed to upper crustal levels. Comparisons with Himalayan tectonics are clearly drawn, but there are significant contrasts such as the long residence time of the proposed Cordilleran channel, and the nature of the channel boundaries.

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Section: Geological Settingmentioning

confidence: 99%

Section: The Cretaceous Mid-crustal Ductile Zonementioning

confidence: 99%

mentioning

confidence: 96%

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An argument for channel flow in the southern Canadian Cordillera and comparison with Himalayan tectonics

Brown

Gibson

2006

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“…Une stratégie plus traditionnelle, mais avec une plus grande chance de réussite puisque développée directement sur le terrain, consiste à contraindre l'âge de déformation en datant différentes phases de matériel leucogranitiques (leucosome, dykes, sill) présentant des relations de recoupement sur le terrain (p. ex. Crowley et al, 2003;Gibson et al, 2005).…”

unclassified

“…Un problème évident concerne la présence de différentes générations de surcroissance sur les minéraux datés (zircon et monazite), et la possibilité de noyaux hérités dans le liquide. La méthode commune de dilution isotopique au spectromètre de masse par ionisation thermique (ID-TIMS) peut être inappropriée lorsque ces minéraux sont intégralement dissous, ce qui donne alors des résultats discordants (Foster et al, 2004;Gibson et al, 2005). Un exemple probant de ce problème provient de la Cordillère canadienne où l'interprétation d'une déformation précambrienne dans le coeur du dôme…”

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Déformations tardi-grenvilliennes dans la ceinture parautochtone (Province de Grenville centrale) : contraintes géochronologiques par couplage de méthodes U–Pb de haute résolution spatiale et de haute précision

et al. 2018

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Late Jurassic flare‐up of the Coast Mountains arc system, NW Canada, and dynamic linkages across the northern Cordilleran orogen

et al. 2017

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Short‐lived, high‐volume magmatic events or flare‐ups in Cordilleran‐style accretionary systems are presumably triggered by the rapid underthrusting of melt‐fertile lithosphere beneath a continental arc during extreme retroarc shortening. New zircon U‐Pb age and trace element geochemical studies of the Coast Mountains batholith were conducted to test this hypothesis and investigate cross‐orogen linkages between the Coast Mountains arc system and adjacent retroarc elements of the Canadian Cordillera. Late Jurassic (155–147 Ma) granitoids of the Saint Elias plutonic suite in southwestern Yukon were emplaced during a widespread magmatic event and correspond to an intrusive rate of ~350 km2/Myr, analogous to the scale of 160–150 Ma flare‐up activity in the Sierra Nevada batholith. The timing of Late Jurassic high‐volume magmatism was coincident with forearc and intraarc deformation events along the length of the Coast Mountains arc from Alaska to British Columbia. Whole‐rock and zircon rare earth element geochemical results from the Saint Elias plutonic suite confirm that continental lithosphere was a key source component for Late Jurassic granitoids, which strengthens the implied relationship between high‐volume arc magmatism and crustal recycling. Well‐documented episodes of late Middle to early Late Jurassic hinterland thrusting and metamorphism in the Intermontane and Omineca belts of the Canadian Cordillera preceded this high‐volume event and therefore support the hypothesis that retroarc shortening was dynamically linked to flare‐up activity. Late Jurassic magmatism was followed by a 140–125 Ma lull in most of the Coast Mountains batholith, which may be linked to ridge subduction, lithospheric delamination, mantle cooling, or plate reorganization.

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U–Th–Pb geochronologic constraints on the structural evolution of the Selkirk fan, northern Selkirk Mountains, southern Canadian Cordillera

Cited by 24 publications

References 59 publications

An argument for channel flow in the southern Canadian Cordillera and comparison with Himalayan tectonics

An argument for channel flow in the southern Canadian Cordillera and comparison with Himalayan tectonics

Déformations tardi-grenvilliennes dans la ceinture parautochtone (Province de Grenville centrale) : contraintes géochronologiques par couplage de méthodes U–Pb de haute résolution spatiale et de haute précision

Late Jurassic flare‐up of the Coast Mountains arc system, NW Canada, and dynamic linkages across the northern Cordilleran orogen

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