| Titre | Age and setting of Permian Slide Mountain terrane ophiolitic ultramafic-mafic complexes in the Yukon: Implications for late Paleozoic-early Mesozoic tectonic models in the northern Canadian
Cordillera |
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| Auteur | van Staal, C R ;
Zagorevski, A; McClelland, W C; Escayola, M P; Ryan, J J;
Parsons, A J; Proenza, J |
| Source | Accretionary orogens; Tectonophysics vol. 744, 2018 p. 458-483, https://doi.org/10.1016/j.tecto.2018.07.008  Accès ouvert |
| Image |  |
| Année | 2018 |
| Séries alt. | Ressources naturelles Canada, Contribution externe 20180125 |
| Éditeur | Elsevier BV |
| Document | publication en série |
| Lang. | anglais |
| DOI | https://doi.org/10.1016/j.tecto.2018.07.008 |
| Media | papier; en ligne; numérique |
| Formats | pdf |
| Province | Yukon |
| Sujets | subduction; zones de subduction; ophiolites; Cordillère; Terrane de Slide Mountain ; Terrane de Yukon-Tanana; tectonique; Permien |
| Programme | GEM2 : La géocartographie de l'énergie et des minéraux Architecture structurelle du Dévonien et du Permien de l'ouest de la Cordillère |
| Diffusé | 2018 07 18 |
| Résumé | (disponible en anglais seulement)
The Yukon Tanana (YTT) and Slide Mountain terranes (SMT) of the Cordillera in Canada and Alaska are commonly interpreted in terms of opening and closing of a
Late Devonian-Permian Japan Sea-style backarc basin behind a continental arc built upon YTT, which rifted from Laurentia during the Famennian-early Mississippian. Upper Devonian mafic-ultramafic complexes in YTT may represent remnants of transitional
oceanic lithosphere exhumed onto the seafloor during rifting.
The studied Clinton Creek and Midnight Dome complexes represent suprasubduction zone ophiolites formed at ca. 265?Ma, consistent with analyses of other SMT ophiolites. Most SMT
ophiolites are dominated by ultramafic rocks, lack sheeted dikes and contain relatively minor volumes of mafic plutonic and volcanic rocks, suggesting they formed in oceanic core complexes characterised by slow spreading and low magma productivity.
The Permian ophiolites formed during or immediately after eclogite formation in YTT, coeval with or immediately preceding emplacement of orogenic peridotites into YTT due to hyperextension. Several tectonic scenarios are discussed to explain these
events. We propose that YTT is a composite terrane comprising a continental block and an oceanic arc-backarc complex with the latter obducted onto the former during the middle Permian-early Triassic Klondike orogeny. Obduction may have come from the
west or east, but east-directed obduction is most consistent with geological constraints. Obduction was followed by initiation of west-dipping subduction east of the composite YTT; slab roll back causing extension in the composite upper plate,
leading to exhumation of orogenic peridotites. Tectonic relationships show many analogies to the collision between Australia and the New Britain-Solomon arc, in which on-going collision in the Huon Peninsula of New Guinea is contemporaneous with
extension in Australian crust in the adjacent Woodlark basin. Syn-orogenic Permian Klondike-cycle calc-alkaline magmatism is attributed to extension in a Woodlark basin-like setting rather than a representing a continental arc. |
| Sommaire | (Résumé en langage clair et simple, non publié)
Le présent document passe en revue plusieurs modèles tectoniques existants qui tentent d'expliquer deux blocs bien connus de l'ancienne croûte
géologique du Yukon (terrane du Yukon-Tanana et terrane de Slide Mountain), et présente les lacunes et les faiblesses existantes de ces modèles de longue date. Grâce aux résultats de la géochronologie moderne et de l'analyse géochimique, et à
l'application plus poussée d'analogues modernes de plaques tectoniques dans le sud-ouest de l'océan Pacifique, des interprétations plus actuelles de la tectonique des anciens terranes sont proposées, lesquelles expliquent mieux la géologie telle que
nous la connaissons aujourd'hui. |
| GEOSCAN ID | 308389 |
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