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Tectonic significance of Upper Cambrian-Middle Ordovician Mafic volcanic rocks on the Alexander Terrane, Saint Elias Mountains, Northwestern Canada

Citation

Beranek, LP and van Staal, CR and Gordee, Sarah M and McClelland, WC and Israel, S and Mihalynuk, M, Tectonic significance of Upper Cambrian-Middle Ordovician Mafic volcanic rocks on the Alexander Terrane, Saint Elias Mountains, Northwestern Canada, Journal of Geology, 120, (3) pp. 293-314. ISSN 0022-1376 (2012) [Refereed Article]


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DOI: doi:10.1086/664788

Abstract

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.

Item Details

Item Type:Refereed Article
Research Division:Earth Sciences
Research Group:Geology
Research Field:Tectonics
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Earth Sciences
Author:Gordee, Sarah M (Ms Sarah Gordee)
ID Code:82544
Year Published:2012
Web of Science® Times Cited:18
Deposited By:Centre for Ore Deposit Research - CODES CoE
Deposited On:2013-02-06
Last Modified:2013-08-27
Downloads:0

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