Northern Cordilleran terranes and their interactions through time

Colpron, Maurice; Nelson, JoAnne; Murphy, Donald C.

doi:10.1130/gsat01704-5a.1

Cited by 258 publications

(224 citation statements)

References 26 publications

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“…Maxson & Tikoff (1996) argued that Cordilleran terrane accretion was the driving mechanism for the Laramide orogeny. Recent work in the Cordillera has emphasized that the number of terranes in the Cordillera is considerably less than originally envisaged by Coney and colleagues, and that many of the remaining terranes may not be suspect but are upper plate fragments that represent arcs and continental ribbons that lay outboard of, and along strike from, the Cordilleran margin (Monger & Knokleberg 1996;Johnston 2001;Colpron & Nelson 2006Colpron et al 2007). Seismic data across the northern Cordilleran orogen suggest that at least some of the accreted terranes are superficial with no deep crustal roots (Snyder et al 2002(Snyder et al , 2009) and may not be major impactors that drove orogenic events (Cawood & Buchan 2007); the terrane accretion model of orogenesis may therefore be 'suspect'.…”

Section: Accretion Of Buoyant Lithosphere (Terrane Accretion)mentioning

confidence: 99%

“…Advancing and retreating settings of accretionary orogens are simplified 2D representations of what is likely to be a more complex response to an overall environment of oblique convergence. Oblique accretion has played an important role in the assembly of the Cordillera in western North America (Johnston 2001;Colpron & Nelson 2006Colpron et al 2007), and probably also in many other orogens.…”

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confidence: 99%

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Accretionary orogens through Earth history

et al. 2009

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Accretionary orogens form at intraoceanic and continental margin convergent plate boundaries. They include the supra-subduction zone forearc, magmatic arc and back-arc components. Accretionary orogens can be grouped into retreating and advancing types, based on their kinematic framework and resulting geological character. Retreating orogens (e.g. modern western Pacific) are undergoing long-term extension in response to the site of subduction of the lower plate retreating with respect to the overriding plate and are characterized by back-arc basins. Advancing orogens (e.g. Andes) develop in an environment in which the overriding plate is advancing towards the downgoing plate, resulting in the development of foreland fold and thrust belts and crustal thickening. Cratonization of accretionary orogens occurs during continuing plate convergence and requires transient coupling across the plate boundary with strain concentrated in zones of mechanical and thermal weakening such as the magmatic arc and back-arc region. Potential driving mechanisms for coupling include accretion of buoyant lithosphere (terrane accretion), flat-slab subduction, and rapid absolute upper plate motion overriding the downgoing plate. Accretionary orogens have been active throughout Earth history, extending back until at least 3.2 Ga, and potentially earlier, and provide an important constraint on the initiation of horizontal motion of lithospheric plates on Earth. They have been responsible for major growth of the continental lithosphere through the addition of juvenile magmatic products but are also major sites of consumption and reworking of continental crust through time, through sediment subduction and subduction erosion. It is probable that the rates of crustal growth and destruction are roughly equal, implying that net growth since the Archaean is effectively zero.Classic models of orogens involve a Wilson cycle of ocean opening and closing with orogenesis related to continent-continent collision. These imply that mountain building occurs at the end of a cycle of ocean opening and closing, and marks the termination of subduction, and that the mountain belt should occupy an internal location within an assembled continent (supercontinent). The modern Alpine -Himalayan chain exemplifies the features of this model, lying between the Eurasian and colliding African and Indian plates (Fig.

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Section: Accretion Of Buoyant Lithosphere (Terrane Accretion)mentioning

confidence: 99%

mentioning

confidence: 99%

Accretionary orogens through Earth history

et al. 2009

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“…Traditionally, the eclogite was assumed to have formed within the Slide Mountain terrane, a mid-to Late Paleozoic ocean basin that developed between the Yukon-Tanana arc and the western margin of North America (e.g. Tempelman-Kluit 1977, 1979Monger et al 1982;Colpron et al 2006aColpron et al , 2007. The St. Cyr area is the least known of four localities that preserve Permian eclogite in the Yukon-Tanana terrane (Figs.…”

Section: Résumémentioning

confidence: 99%

“…1; Colpron et al 2006aColpron et al , 2007. The terrane comprises a mid-to Late Paleozoic composite arc-forearc system built upon a sliver(s) of continental crust rifted from western Laurentia (Nelson et al 2013 and references therein).…”

Section: Regional Geologic Settingmentioning

confidence: 99%

Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

Petrie

Gilotti

McClelland

et al. 2015

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SUMMARYThe St. Cyr area near Quiet Lake hosts well-preserved to variably retrogressed eclogite found as sub-metre to hundreds of metre-long lenses within quartzofeldspathic schist in southcentral Yukon, Canada. The St. Cyr klippe consists of structurally imbricated, polydeformed and polymetamorphosed units of continental arc crust and ultramafic-mafic rocks. Eclogite-bearing quartzofeldspathic schist forms thrust slices in a 30 km long by 6 km wide, northwest-striking outcrop belt. The schist unit comprises metasedimentary and felsic intrusive rocks that are intercalated on the metre to tens of metres scale. Ultramafic rocks, serpentinite and associated greenschist-facies metagabbro form imbricated tectonic slices within the eclogite-bearing quartzofeldspathic unit, which led to a previously held hypothesis that eclogite was exhumed within a tectonic mélange. The presence of phengite and Permian zircon crystallized under eclogite-facies metamorphic conditions in the quartzofeldspathic host rocks indicate that the eclogite was metamorphosed in situ together with the schist as a coherent unit that was part of the continental arc crust of the Yukon-Tanana terrane, rather than a mélange associated with the subduction of oceanic crust of the Slide Mountain terrane. Petrological, geochemical, geochronological and structural similarities link St. Cyr eclogite to other high-pressure localities within Yukon, indicating the high-pressure assemblages form a larger lithotectonic unit within the Yukon-Tanana terrane. Geoscience Canada, v. 42, http://www.dx

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“…lithosphere was subducted beneath western North America to form the voluminous Cordilleran type magmatic belts such as the Peninsular Ranges, Sierra Nevada, Idaho, and Coast batholiths, most Cordilleran geologists have embraced models predicated upon long-lived eastward subduction (Burchfiel andDavis 1972, 1975;Price 1981;Dickinson 2004;Colpron et al 2007;Ingersoll 2008). 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.…”

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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Northern Cordilleran terranes and their interactions through time

Cited by 258 publications

References 26 publications

Accretionary orogens through Earth history

Accretionary orogens through Earth history

Geologic Setting of Eclogite-facies Assemblages in the St. Cyr Klippe, Yukon–Tanana Terrane, Yukon, Canada

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

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