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TitreTectonic significance of Upper Cambrian - Middle Ordovician mafic volcanic rocks on the Alexander Terrane, Saint Elias Mountains, northwestern Canada
AuteurBeranek, L P; van Staal, C R; Gordee, S M; McClelland, W C; Israel, S; Mihalynuk, M
SourceGeology vol. 120, no. 3, 2012 p. 293-314,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20110266
Documentpublication en série
Mediapapier; en ligne; numérique
ProvinceColombie-Britannique; Yukon
SNRC104L; 104M/03; 104M/04; 104M/05; 104M/12; 104O/09; 104O/15; 104O/16; 104P; 115A; 115B; 115C
Lat/Long OENS-141.0000 -134.0000 61.2500 57.5000
Sujetsroches ignées; roches volcaniques mafiques; roches volcaniques; basaltes; tholéiites; cadre tectonique; interprétations tectoniques; pétrogenèse; décrochement horizontal; crevasses; paléogéographie; Terrane d'Alexander ; tectonique; Paléozoïque; Ordovicien; Cambrien
Illustrationslocation maps; photographs; stratigraphic columns; plots; ternary diagrams; tables
ProgrammeGisements polymétalliques - nord-ouest de la Cordillère canadienne (Yukon et Colombie-Britannique), GEM : La géocartographie de l'énergie et des minéraux
Résumé(disponible en anglais seulement)
Upper Cambrian to Middle Ordovician mafic volcanic rocks of the Donjek assemblage comprise the oldest exposed units of the Alexander terrane in the Saint Elias Mountains of northwestern Canada. In this study, we use the geochemical and geological characteristics of these rocks to decipher their tectonic setting, petrogenetic history, and relationship to the early Paleozoic Descon arc system of the Alexander terrane in southeastern Alaska. Donjek assemblage volcanic rocks are subdivided into three geochemical types: transitional basalt (type I), light rare earth–enriched island-arc tholeiite to calc-alkaline basalt (type II), and enriched mid-ocean ridge basalt to ocean-island basalt (type III). Simple petrogenetic models illustrate that the basalts were generated by the decompressional partial melting of enriched asthenospheric mantle and variably mixed with depleted mantle and subduction-related components. Analogous geochemical signatures for modern Sumisu Rift and Okinawa Trough lavas imply that the Donjek assemblage basalts erupted during the rifting of the Descon arc. This model provides a new comparative framework for terranes of Siberian, Baltican, and Caledonian affinity in the North American Cordillera and, in particular, suggests a paleogeographic connection to rift-related magmatism in the Seward Peninsula region of the Arctic Alaska - Chukotka terrane.