Acado-Baltic Volcanism in Eastern North America and Western Europe: Implications for Cambrian Tectonism

Authors

  • John D. Greenough Department of Earth Sciences, Memorial University of Newfoundland St. John's, Newfoundland, Canada, A1B 3X5; Present address: Department of Geology, Saint Mary's University, Halifax, Nova Scotia, Canada, B3H 3C3.
  • V. S. Papezik Department of Earth Sciences, Memorial University of Newfoundland; Passed away summer 1984.

DOI:

https://doi.org/10.4138/1609

Abstract

Although small in volume, Cambrian volcanic rocks associated with Acado-Baltlc sedimentary rocks In Newfoundland, New Brunswick, and Nova Scotia, Norway and Poland display characteristics indicating formation in a tensional tectonic setting. They generally form bimodal (basalt-rhyolite) suites. Mafic rocks are of both alkaline and tholeiitic affinities but all have withln-plate major element and trace element characteristics. The small volume and low frequency of eruption suggests that in most cases the volcanic rocks resulted from only small amounts of lithospherlc extension, and that rupturing and separation of plates may not have taken place. Volcanism over the Acado-Baltic province appears to have been less common in the Late Cambrian than in the Early and Middle Cambrian. This suggests that tension persisted throughout the Early and Middle Cambrian, but waned in the Upper Cambrian, possibly in direct or indirect response to processes which led to closing of the lapetus Ocean. RÉSUMÉ Malgré un volume restraint, les volcanites cambriennes associées aux roches sédimentaires acado-baltiques à Terre-Neuve, au Nouveau-Brunswick ainsi qu'en Nouvelle-Écosse, Norvège et Pologne montrent des caractéristiques qui suggèrent leur formation en régime tectonlque de tension. Elles foment généralement des suites bimodales (basalte-rhyolite). Les roches mafiques ont des affinites tant alcalines que tholèiitiques bien qu’elles révèlent un caractére intraplaque au plan des éléments majeurs et en traces. Du volume restreint et de la faible fréquence éruptive, on retire l’impression que, pour la plupart, ces volcanites ne reultent que d'une extension lithospherique de faible valeur et qu'aucune rupture ou séparation des plaques n'a eu lieu. La province acado-baltique aurait connu un volcanisme mollis prononce à l'eo-Cambrlen et au Cambrlen moyen qu'au tardi-Cambrlen. Ceci semble indiquer que la tension à perdure de l'eo-Cambrlen au Cambrlen moyen et s'est. par la suite, attenuée au Cambrlen supérieur, possiblement en réponse directe ou indirecte aux processus qui ont suscité la fermeture de l’océan lapetus. [Traduit par le journal]

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Published

1986-12-01

How to Cite

Greenough, J. D., & Papezik, V. S. (1986). Acado-Baltic Volcanism in Eastern North America and Western Europe: Implications for Cambrian Tectonism. Atlantic Geoscience, 22(3). https://doi.org/10.4138/1609

Issue

Vol. 22 No. 3 (1986)

Section

Articles

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