Geochemistry and tectonic setting of the late Precambrian Folly River Formation, Cobequid Highlands, Avalon Terrane, Nova Scotia: a continental rift within a volcanic-arc environment

Auteurs-es

  • Georgia Pe-Piper Department of Geology, St. Mary's University, Halifax, Nova Scotia B3H 3C3, Canada
  • J. Brendan Murphy Department of Geology, St. Francis Xavier University, Antigonish, Nova Scotia B2G ICO, Canada

DOI :

https://doi.org/10.4138/1679

Résumé

The late Proterozoic Folly River Formation of the Cobequid Highlands, Nova Scotia, is a volcano-sedimentary sequence within the Avalon Terrane. The succession consists of interlayered mafic volcanic rocks and thinly laminated volcanogenic turbidites and is associated with abundant mafic dykes that are inferred to have fed the volcanic eruptions. The formation occurs exclusively between the Rockland Brook and Cobequid faults. The basalts and dykes are Fe- and Ti-rich, differentiated, within-plate continental tholeiites. Their emplacement is attributed to limited continental rifting. The Folly River Formation is similar in lithology, geochemistry and stratigraphy to the Clydesdale Formation in the Antigonish Highlands and is probably penecontemporaneous with arc-related volcanic sequences in both the Cobequid and Antigonish highlands. Hence it is concluded that the Folly River Formation formed in a rifting environment within a volcanic arc. RÉSUMÉ La Formation tardiprotérozoique de Folly River (Monis Cobequid, Nouvelle-Écosse) est une série volcano-sédimentaire au sein de la Lanière d'Avalon. La succession consiste en un interlitage de volcanites mafiques et de turbidites volcanogènes finement laminèes. Lui sont associées d'abondants dykes mafiques qui auraient nouiri les éruptions volcaniques. La formation ne se rencontre qu'entre les failles de Rockland Brook et de Cobequid. Les basaltes et les dykes sont des tholéiites intraplaques continentales, différenciées et riches en Fe ainsi qu'en Ti. On attribue leur emplacement à l'ouverture restreinte d'un rift continental. La Formation de Folly River ressemble, par sa litnologie, sa géochimie et sa stratigraphie, à la Formation de Clydesdale dans les Monts Antigonish. Elle est probablement pénécontemporaine des series volcaniques relives aux arcs des monts Cobequid et Antigonish. On conclut done que la Formation de Folly River s'&ablit en régime d'ouverture à l’intéieur d'un arc volcanique. [Traduit par le journal]

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Publié-e

1989-08-01

Comment citer

Pe-Piper, G., & Murphy, J. B. (1989). Geochemistry and tectonic setting of the late Precambrian Folly River Formation, Cobequid Highlands, Avalon Terrane, Nova Scotia: a continental rift within a volcanic-arc environment. Atlantic Geoscience, 25(2). https://doi.org/10.4138/1679

Numéro

Vol. 25 No. 2 (1989)

Rubrique

Articles

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