Petrology of the Shelburne and Barrington Passage plutons, southern Nova Scotia

Authors

  • H. Dean Rogers Department of Geology, Acadia University, Wolfville, Nova Sootia BOP 1XO
  • Sandra M. Barr Department of Geology, Acadia University, Wolfville, Nova Sootia BOP 1XO

DOI:

https://doi.org/10.4138/1637

Abstract

The Shelburne and Barrington Passage plutons are adjacent, but contrasting. Intrusions located on the southern coast of Nova Scotia. The Shelburne Pluton consists mainly of monzogranite and granodiorite, with minor areas of tonalite, whereas the Barrington Passage Pluton consists of tonalite gradational to quartz diorite. Both plutons have petrochemical characteristics consistent with derivation from netasedintentary source rocks. Major and trace element trends within the Barrington Passage tonalite suggest that magma evolution was controlled by biotlte fractionation, whereas plagioclase and biotlte fractionation may have produced much of the variation within the Shelburne Pluton. Tonalite within the Shelburne Pluton has higher Sr than the Barrington Passage tonalite, and may have formed by plagioclase accumulation from co-magmatic granodiorite and monzogranite of the Shelburne Pluton. On the basis of previously published Ar date, the Barrington Passage Pluton was probably emplaced during the main phase of regional netaaorphism related to the Acadian Orogeny (about 400 Ma). A Rb-Sr whole-rock lsochron suggests an age of 466 + 17 Ma for the Shelburne Pluton, although published Ar data have indicated a Devonian age. The ages of these plutons and others in the southernmost Heguma Terrane must be better constrained before a reliable assessment of petrogenesls and tectonic history can be made. RÉSUMÉ Les plutons de Shelburne et Barrington Passage sont des intrusions adjacentes qui contraatent et sont situées sur la côte méridionale de la Nouvelle-Écosse. Le Pluton de Shelburne se compose surtout de monzogranite et granodiorite ponctuées de tonalite; par contre. le Pluton de Barrington Passage est formé de tonalite passant graduellement à une diorite quartzique. Lea caractéres pétrochimlques de cea deux plutons s'accordent avec une provenance etasedinentaire. À la lumiére des éléments majeurs et en traces, le fractlonnement de la biotlte semble avoir condltlonne l’évolution magmatlque de la tonalite de Barrington Passage alors que la variation dans le Pluton de Shelburne semble assujettle en grande partle au fractlonnement du plagioclase et de la biotlte. La tonalite présente dans le Pluton de Shelburne renferme une plus grande proportion de Sr que la tonalite de Barrington Passage et pourralt avoir procédé de l’accumulation de plagioclase À partir d'un mélange magmatlque de granodiorite et monzogranite. Si on en Juge par les données déjà publiées sur l'argon, le Pluton de Barrington Passage s'est probablement mis en place dursnt la phase principale de métamorphisme régional relite A l'orogenie acadienne (environ 400 Ha). Un iBOchrone Rb-Sr sur roche entiere suggère un àge de 466 + 17 Ha pour le Pluton de Shelburne même si L’lnformatlon publiée sur l’argon à lndique un âge dévonien. On se dolt de preciser l'âge de ces intrusions ainsi que des autres plutons dans la partie la plus mériidionale de la Lanière de Heguma si on veut lever tout doute sur leur petrogenèse et leur histoire tectonlque. [Traduit par le journal]

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Published

1988-04-01

How to Cite

Rogers, H. D., & Barr, S. M. (1988). Petrology of the Shelburne and Barrington Passage plutons, southern Nova Scotia. Atlantic Geoscience, 24(1). https://doi.org/10.4138/1637

Issue

Vol. 24 No. 1 (1988)

Section

Articles

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