Cordilleria Revisited, with a Three-Dimensional Model for Cretaceous Tectonics in British Columbia

Lambert, R. St J.; Chamberlain, V. E.

doi:10.1086/629192

Cited by 24 publications

(13 citation statements)

References 31 publications

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“…Over the years a few workers (Moores 1970;Mattauer et al 1983;Chamberlain and Lambert 1985;Lambert and Chamberlain 1988;Moores 1998) proposed alternative models involving collision of North America with various arcs above westward-dipping subduction zones but they failed to garner traction in the community. Some more recent models for Cordilleran development, created to better explain the overall development of the orogen, posit that the leading edge of North America was subducted to the west beneath an exotic ribbon continent during Cretaceous orogenesis (Johnston and Borel 2007;Johnston 2008;Hildebrand 2009Hildebrand , 2013.…”

Section: Sommairementioning

confidence: 99%

Geology, Mantle Tomography, and Inclination Corrected Paleogeographic Trajectories Support Westward Subduction During Cretaceous Orogenesis in the North American Cordillera

Hildebrand

2014

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Geological evidence, including the presence of two passive margin platforms, juxtaposed and mismatched deformation between North America and more outboard terranes, as well as the lack of rift deposits, suggest that North America was the lower plate during both the Sevier and Laramide events and that subduction dipped westward beneath the Cordilleran Ribbon Continent (Rubia). Terranes within the composite ribbon continent, now present in the Canadian Cordillera, collided with western North America during the 125–105 Ma Sevier event and were transported northward during the ~80–58 Ma Laramide event, which affected the Cordillera from South America to Alaska. New high-resolution mantle tomography beneath North America reveals a huge slab wall that extends vertically for over 1000 km, marks the site of long-lived subduction, and provides independent verification of the westward-dipping subduction model. Other workers analyzed paleogeographic trajectories and concluded that the initial collision took place in Canada at about 160 Ma – a time and place for which there is no deformational thickening on the North American platform – and later farther west where subduction was not likely westward, but eastward. However, by utilizing a meridionally corrected North American paleogeographic trajectory, coupled with the geologically most reasonable location for the initial deformation, the position of western North America with respect to the relict superslab parsimoniously accounts for the timing and extents of both the Sevier and Laramide events. SOMMAIRELes indications géologiques, en particulier la présence de deux marges de plateforme passives, de déformations adjacentes non-conformes entre l’Amérique du Nord et les terranes extérieurs, ainsi que l’absence de gisements de rift, permet de croire que l’Amérique du Nord était la plaque sous-jacente durant les événements de Sevier et de Laramide et que la subduction plongeait vers l’ouest sous le continent rubané de la Cordillères (Rubia). Les terranes du continent rubané composite, maintenant au sein de la Cordillère canadienne, sont entrés en collision avec l’ouest de l’Amérique du Nord durant l’événement Sevier (125-105 Ma), et ont été transportés vers le nord durant l’événement Laramide (~80–58 Ma), laquelle a affecté la Cordillère, de l’Amérique du Sud à l’Alaska. Une nouvelle tomographie haute résolution du manteau sous l’Amérique du Nord montre la présence d’un gigantesque mur de plaques vertical qui s’étend sur 1 000 km, marque le site d’une subduction de longue haleine, et offre une validation indépendante du modèle d’une subduction à pendage vers l’ouest. D’autres chercheurs ont analysé les trajectoires paléogéographiques et conclu que la collision initiale s’est produite au Canada vers 160 Ma – un moment et un endroit sans épaississement par déformation sur la plateforme d’Amérique du Nord – et plus tard plus à l’ouest, là où la subduction n’était vraisemblablement pas vers l’ouest, mais vers l’est. Cela dit, en considérant une trajectoire paléogéographique de l’Amérique du Nord corrigée longitudinalement, avec la position géologique la plus probable de la déformation initiale, la position de la portion ouest de l’Amérique du Nord par rapport aux restes de la super-plaque explique alors facilement la chronologie et l’étendue des épisodes Sevier et Laramide.

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Section: Sommairementioning

confidence: 99%

Geology, Mantle Tomography, and Inclination Corrected Paleogeographic Trajectories Support Westward Subduction During Cretaceous Orogenesis in the North American Cordillera

Hildebrand

2014

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“…The fold and thrust belt is antithetic to a single subduction zone active during the orogeny (e.g., Dickinson, 2004;Ernst, 2005;Ducea, 2001). A countervailing view is that Cordilleran orogens are in fact collisional, just as with the intracratonic orogens (e.g., Chamberlain and Lambert, 1985;Hildebrand, 2013Hildebrand, , 2009Johnston, 2008;Lambert and Chamberlain, 1988;Mattauer et al, 1983;Moores et al, 2002;Moores, and Day, 1984;Moores, 1970Moores, , 1998, and that the foreland fold and thrust belt is synthetic (i.e., parallel) to the subduction direction of colliding island arcs or continental slivers (ribbon continents) that were emplaced along subduction zones dipping away from the continent. Large-scale orogen-parallel movements are also present (e.g., Hildebrand, 2013, and references therein).…”

Section: External Fold-thrust Beltmentioning

confidence: 99%

Tectonics: 50 years after the Revolution

Moores

Yıkılmaz

Kellogg

2013

The Web of Geological Sciences: Advances, Impacts, and Interactions

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“…Two main alternative tectonic models for the affinity of the gneisses of the Malton gneiss complex are discussed below: (i) they form basement to a far-travelled allochthonous terrane displaced northward by Mesozoic dextral strike-slip faults (e.g., Urnhoeffer 1987;Lambert and Chamberlain 1988); and (ii) they formed part of the thinned western edge of the North American craton.…”

Section: Restoration Of the Basement Gneissesmentioning

confidence: 99%

“…Chamberlain and Lambert (1985), Chamberlain et al (1985), and Lambert and Chamberlain (1988) proposed a suture in the Southern Rocky Mountain Trench primarily on the basis of geochemical dissimilarities between amphibolites of the Malton and Bulldog gneiss bodies. However, the similarity of gneiss and cover lithologies on either side of the Trench, the presence of multiple phases of amphibolites on both sides of the Trench, the relationship of the gneisses to the Windermere Supergroup, and structural (Simony et al 1980) and stratigraphic (Ross and Murphy 1988) that the Malton, Blackman, Bulldog, Gold Creek, Hugh Allan, and Yellowjacket gneiss bodies are thrust slices that form parts of the same heterogeneous basement complex ( Fig.…”

Section: Introduction Geological Setting Of the Malton Complexmentioning

confidence: 99%

Proterozoic gneisses of the Malton Complex, near Valemount, British Columbia: U–Pb ages and Nd isotopic signatures

McDonough¹,

Parrish²

1991

Can. J. Earth Sci.

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Proterozoic gneisses of the Malton Complex in the vicinity of Valemount, British Columbia, occur in a series of lithologically and structurally complex, fault-bounded slices of crystalline basement and interleaved cover. Gneisses of the Malton Complex span the Southern Rocky Mountain Trench and underlie the western part of the Rocky Mountain fold and thrust belt and the eastern part of the Omineca Belt of the Canadian Cordillera. Structural and stratigraphic relationships indicate that they formed the basement upon which an enigmatic quartzite unit and the Late Proterozoic Windermere Supergroup were deposited.The Yellowjacket and Bulldog gneisses, on the east side of the Rocky Mountain Trench, have yielded four U–Pb zircon crystallization ages of ca. 1870 Ma, with εNd(T) values of −2.6 to −3.4. The Hugh Allan gneiss, also on the east side of the trench but separated from the Yellowjacket gneiss by a major thrust fault, includes leucocratic granite gneiss having a zircon U–Pb age of [Formula: see text], which has intruded an older (undated) lithologically heterogeneous assemblage of gneiss. The basal Windermere succession of the Valemount region is inferred to be younger than ca. 740 Ma, since these intrusions are not found within the Late Proterozoic stratified rocks.Augen granitoid orthogneiss of the Malton Range on the west side of the Rocky Mountain Trench has been dated as [Formula: see text] using zircons. A second sample yields data suggesting an age between 2050 and 2100 Ma, but its interpretation is uncertain because of scatter in analyses and possible zircon inheritance. The latter sample has an εNd(T) at 1990 Ma of −2.6. Nd model ages for the Malton, Yellowjacket, and Bulldog samples range from 2.45 to 2.56 Ga, indicating that the igneous protoliths were derived from a source that probably had some component of Archean crustal material involved.The U–Pb ages and Nd model ages are quite similar to those of rocks underlying portions of Alberta and the western Canadian Shield, specifically the Fort Simpson terrane, the Great Bear magmatic zone, and parts of the Thelon–Taltson arc. This evidence, as well as structural and stratigraphic arguments, links the Malton Complex gneisses with those of the Canadian Shield, precluding their derivation by large-magnitude displacements from the southwestern United States. Structural analysis indicates that they restore to locations 100–200 km southwest of their present exposure.Structural, stratigraphic, and isotopic data indicate that the Southern Rocky Mountain Trench is not a suture.

show abstract

Cordilleria Revisited, with a Three-Dimensional Model for Cretaceous Tectonics in British Columbia

Cited by 24 publications

References 31 publications

Geology, Mantle Tomography, and Inclination Corrected Paleogeographic Trajectories Support Westward Subduction During Cretaceous Orogenesis in the North American Cordillera

Geology, Mantle Tomography, and Inclination Corrected Paleogeographic Trajectories Support Westward Subduction During Cretaceous Orogenesis in the North American Cordillera

Tectonics: 50 years after the Revolution

Proterozoic gneisses of the Malton Complex, near Valemount, British Columbia: U–Pb ages and Nd isotopic signatures

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