Geochemistry of Ordovician volcanic rocks of the Tetagouche Group of southwestern New Brunswick
DOI :
https://doi.org/10.4138/1684Résumé
The Lower to Middle Ordovician volcanic suite of the Tetagouche Group from the southwestern part of the Miramichi Terrane in the Woodstock-Meductic area in southwestern New Brunswick is composed of a bimodal basalt-rhyolite association. The basaltshave calc-alkalic characteristics and were emplaced on the continental crust in a volcanic arc or back-arc environment. The rhyolites were probably derived by melting of an amphibolite-facies crust. The basalts differ from those of the Tetagouche Group from the Bathurst area which include within-plate basalts and MORB. However, they both may be part of a single Ordovician arc-back-arc system. RÉSUMÉ Le cortege volcanique du Groupe de Tetagouche (Ordovicien médian à inférieur) dans la portion sud-ouest de la Lanière de Miramichi (région de Woodstock-Meductic, sud-ouest du Nouveau-Brunswick) se compose d'une association bimodèle de basalte et rhyolite. Les basaltes présentent des caractéres calco-alcalins et ils se sont mis en place sur la croûte continentale dans un milieu d'arc insulaire ou de rétro-arc. Les rhyolites proviennent probablement de la fonte d'une croûte de faciès à amphibolites. Les basaltes différent de ceux du Groupe de Tetagouche dans la région de Bathurst, qui comprennent des basaltes intra-plaques et des MORB, quoique tous deux puissent faire partie d'un système arc:rétro-arc ordovicien unique. [Traduit par le journal]Téléchargements
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