| Titre | Cretaceous exhumation of the Yukon Tanana Terrane, northern Canadian Cordillera: insights from low-temperature (U-Th)/He thermochronology |
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| Auteur | Gaudreau, E; Schneider, D; Ryan, J; Audet, P |
| Source | Orogeny to ore: Cordilleran Tectonics Workshop 2017; 2017 p. 63  Accès ouvert |
| Liens | Online - En
ligne (complete volume - volume complet, PDF, 18.2 MB)
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| Année | 2017 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20190377 |
| Réunion | Cordilleran Tectonics Workshop 2017; Vancouver, BC; CA; février 24-26, 2017 |
| Document | livre |
| Lang. | anglais |
| Media | en ligne; numérique |
| Formats | pdf |
| Sujets | Terrane de Yukon-Tanana; Cordillère canadienne; géochronologie; Sciences et technologie; Nature et environnement |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Redéfinition des blocs de la croûte terrestre de l'ouest de la Cordillère |
| Diffusé | 2017 02 01 |
| Résumé | (disponible en anglais seulement)
Despite the relatively high elevation of the northern Canadian Cordillera, the lithosphere is about 150 km thinner than the adjacent craton, reflecting the
contrast in thermal regime and crustal exhumation history between the craton and mountainous Cordilleran region. The models commonly used to explain the present-day lithospheric structure of the cordillera are downwelling and delamination of the
lower lithosphere. To better resolve the model for the northern Canadian Cordillera, the exhumation history and thermal structure within the Yukon Tanana Terrane will be elucidated, from which lithospheric strength profiles may be evaluated. The
first phase of this study is determining the timing and rate of exhumation of different crustal blocks within this area of the cordillera using low-temperature (U-Th)/He thermochronology. Five crustal blocks spanning between 50 and 150 km wide have
been defined using magnetic anomaly data and previously published structural and geochronological data. Numerical modeling of the zircon and apatite thermochronology data indicates rapid cooling (~10°C/m.y.) during the middle to late Cretaceous for
the crustal block south of the Yukon River Thrust Fault and east of Yukon River, reaching surface temperatures at c. 70 Ma. To the northwest, the adjacent Permian tectono-metamorphic domain exhumed rapidly to mid-crustal depths by the early
Cretaceous, followed by a 70 m.y. period of monotonic (~1°C/m.y.) cooling. The models require the Permian domain to quickly reach surface conditions between c. 80 and 90 Ma, preceding the exhumation to shallow depths of the mid-Cretaceous metamorphic
core complex in western Yukon. In this portion of the cordillera, most of the tectonic activity in the shallow crust abates by the late Cretaceous. These results mark an older exhumation history compared to the Alaskan and southern Canadian
Cordillera, which define a dominant Eocene signature. Understanding the different processes governing orogenic plateau formation in the northern and southern Canadian Cordillera is significant for understanding the evolution of craton
margins. |
| GEOSCAN ID | 321652 |
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