Petrology and geochemistry of Devono-Carboniferous volcanic rocks in Nova Scotia

Authors

  • J. Dostal Department of Geology Saint Mary's University, Halifax, N.S. Canada B3H 3C3
  • J. D. Keppie Nova Scotia Department of Mines and Energy P.O. Box 1087, Halifax, N.S. Canada B3J 2X1
  • C. Dupuy Centre Geologique et Geophysique, U.S.T.L. 34060 Montpellier Cedex, France

DOI:

https://doi.org/10.4138/1566

Abstract

The Devono-Carboniferous volcanic rocks of Nova Scotia include Middle Devonian basalts from the McAras Brook Formation in the northern Antigonlsh Highlands (Ballantynes Cove and McAras Brook areas), Kiddle Devonian and Carboniferous basalts and rhyolites of the Fountain Lake Group In the Cobequid Highlands and the Upper Devonian-Lower Carboniferous basalts and rhyolites of the Fisset Brook Formation in Cape Breton Island. The volcanic rocks were extruded upon the continental crust in an lntraplate setting. The basalts are tholelitic except those from Ballantynes Cove which are alkaline. All these basalts could have been derived from a similar upper mantle source - garnet peridotite. Rhyolites were probably generated by crustal anatexis related to the ascending basaltic magma. The Devono-Carboniferous volcaniant is probably connected with rifting along faults bounding the Magadalen pull-apart basin. In the Cobequid Highlands, the volcanlsm appears to be spatially and temporally associated with plutonism. RÉSUMÉ Les roches volcaniquée Dévono-Carbonifères de la Nouvelle-Écosse comprennent: les basaltes de la formation McAras Brook (Dévonian moyen) dans la partie nord des hautes-terres d'Antigonlsh (régions de Ballantynes Cove et de McAras Brook); les basaltes et les rhyolites du groupe Fountain Lake (Dévonien moyen et Carbonifère) des monts Cobequid; et les basaltes et rhyolites (Dévonien supérieur-Carbonifère inférieur) de la formation Fisset Brook su l’ile du Cap-Breton. Les roches volcaniquée furent repandues à la surface de la croùte continentale dans un contexte intraplaque. Les basaltes sont tous tholèiltiques à l'exception de ceux de Ballantynes Cove qui sont alcallns. Tous ces basaltes pourralent provenir d'une même source située dans la partie supérieure de manteau terrestre - péridotite à grenat. Les rhyolites résultent probablement de l'anatexie de la croùte associée à la montée du magma basaltique. Le volcanisme Dévono-Carbonifère est probablement relié à une fissuration le long des failles qui encadrent le bassin de déchirement des Madeleines. Dans les monts Cobequid, le volcanisme semble associé de façon spatio-temporelle au plutonisine. [Traduit par le Journal]

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Published

1983-08-08

How to Cite

Dostal, J., Keppie, J. D., & Dupuy, C. (1983). Petrology and geochemistry of Devono-Carboniferous volcanic rocks in Nova Scotia. Atlantic Geoscience, 19(2). https://doi.org/10.4138/1566

Issue

Vol. 19 No. 2 (1983)

Section

Articles

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