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TitreBoninitic magmatism in a continental margin setting, Yukon- Tanana terrane, southeastern Yukon, Canada
AuteurPiercey, S J; Murphy, D C; Mortensen, J; Paradis, S
SourceGeology vol. 29, no. 8, 2001 p. 731-734,<0731:BMIACM>2.0.CO;2 (Accès ouvert)
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100110
ÉditeurGeological Society of America
Documentpublication en série
Mediapapier; en ligne; numérique
SNRC105G/01; 105G/02; 105G/03; 105G/04; 105G/05; 105G/06; 105G/07; 105G/08
Lat/Long OENS-132.0000 -131.2500 61.5000 61.0833
Sujetsmagmatisme; magmas; croûte continentale; Terrane de Yukon-Tanana; pétrologie ignée et métamorphique; géochimie; stratigraphie
Illustrationslocation maps; cross-sections; plots
Résumé(disponible en anglais seulement)
Mid-Paleozoic mafic rocks in the Finlayson Lake region of the Yukon-Tanana terrane, southeastern Yukon, Canada, have the diagnostic geochemical signatures of boninites: high MgO, Cr, Ni, and Co contents, intermediate SiO2 contents, high Mg#'s (MgO/ (MgO+FeO*), Al2O3/TiO2, and Zr(Hf)/middle rare earth element (REE) ratios; low TiO2, REE, and high-field-strength element contents; and U-shaped primitive mantle - normalized trace element patterns. However, unlike most modern and ancient boninitic rocks that are typically associated with intraoceanic realms, those from the Finlayson Lake region are part of a mid-Paleozoic continental margin arc-backarc magmatic system. We propose a model in which the boninitic rocks from the Finlayson Lake region formed as a result of spreading ridge propagation into an arc built on composite basement of oceanic and continental crust. In the oceanic segment, upwelling asthenosphere induced melting of a subducted-slab metasomatized refractory mantle source to form boninitic magmatism. In the continental sector, upwelling asthenospheric mantle, and/or the melts derived thereof, induced crustal melting, which explains the large volume of temporally equivalent felsic volcanic and intrusive rocks.