Anorthosltes and Gabbroic Bodies in northern Cape Breton Island, Nova Scotia

Authors

  • C. Dupuy Centre Geologique et Geophysique, U.S.T.L., 34060 Montpeller Cedex, France
  • J. Dostal Department of Geology Saint Mary*a University, Halifax, Nova Scotia B3H 3C3
  • P. K. Smith Nova Scotia Department of Mines and Energy, P.O. Box 1087, Halifax, Nova Scotia B3J 2X2
  • J. D. Keppie Nova Scotia Department of Mines and Energy P. 0. Box 1087, Halifax, Nova Scotia B3J 2X2

DOI:

https://doi.org/10.4138/1602

Abstract

Several lensoidal anorthositic bodies of probable Precaabrian age, are exposed in northern Cape Breton Island within a central fault-banded block of quartzofeldspathlc gneisses. One of these, the Red River anorthoslts coaplex Cell ka long and up to 1 ka Hide) ranges free anorthosite to anorthositlc gabbro with high Al2O3 and Sr contents and large positive Eu anomalies resulting mainly from plagloolase accumulation. Following an episode of polyphase deformation and amphilbolite facles metamorphism, a monzodlorite-gabbro body of unknown age was intruded into both the anorthosite and Its host rocks. The geochemistry of this Intrusion indicates that It Is calc-alkaline. Granite sheets, Intrusive Into the aonzodlorlte-gabbro body, do not appear to be comagmatic based upon the trace element chemistry. These sheets may be correlated with granitic plutons in the Cape North area which have been dated at 330 ±23 Ma. RÉSUMÉ Plusieurs masses anorthositiques, vraisemblablement d'âge précambrien, affieurent de manière lentlculaire eu sein d'un amas central de gneiss quartzofeldspathique, bordé par des failles, dans la nord de l’ile du Cap-Breton. Paral celles-ci, le compiexe d'anorthosite de Red River (d'environ 11 ka da longueur et jusqu'à 1 km de largsur) s'étage des anorthosites aux gabbros anorthositlques, montre de haute contenus en Al2O3 et Sr et a fouml des anomalies élevées en Eu résultant prlncipalament de L’accummulation des plagloclasses. Aprte un épisode de déformation polyphasée et métamorphisme au faciès amphibolite, un corps de monzonite et gabbro d'âge inconnu s'est introduit tant dans l'anorthosite que dans ses ancalssants. La géochimis de cette intrusion trahit une nature calco-alcaline. La chimie des éléments en traces tend à nier le comagmatisme des granites en nappe intruslfs dans le corps de monzodiorite-gabbro. Ceux-ci s'apparentent plutôt aux plutons granitiques dans la région de Cape North qui sent dates à 330 ±23 Ma. [Traduit par le journal]

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Published

1986-08-01

How to Cite

Dupuy, C., Dostal, J., Smith, P. K., & Keppie, J. D. (1986). Anorthosltes and Gabbroic Bodies in northern Cape Breton Island, Nova Scotia. Atlantic Geoscience, 22(2). https://doi.org/10.4138/1602

Issue

Vol. 22 No. 2 (1986)

Section

Articles

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