A Re-Appraisal of the Alaskite/Muscovite-Biotite Granite Suite of Halifax County, Nova Scotia

Authors

  • T. E. Smith Department of Geology, University of Windsor, Windsor, Ontario N9B 3P4
  • D. Peck Department of Geology, University of Windsor, Windsor, Ontario N9B 3P4
  • P. E. Holm Department of Geology, University of Windsor, Windsor, Ontario N9B 3P4

DOI:

https://doi.org/10.4138/1600

Abstract

New mapping, petrography and geochemistry, including REE analyses, indicate that a much larger area of muscovite-biotite granite and fewer alaskite dykes occur in the Halifax - St. Margarets Bay area than was originally thought. The rocks of this area were formed by fractional crystallization of quartz, plagioclase, biotite, zircon, ilmenite, apatite, and monazite. The presence of monazite in the fractional crystallization assenmlage is essential to account tor ttie strong depletion of the rare earth element contents and fractionation of the light rare earth elements noted in these rocks. They have been affected by a pervasive hydrothermal recrystallization and by localized development of pegmatitic vugs and a greisen-bordered sheeted vein complex. A greisen-bordered sheetea vein complex has developed in part of the muscovite-biotite granite south of Sandwich Point, ana although this zone shows all of the features characteristic of the mineralization elsewhere in the batitolith, it is barren. RÉSUMÉ Une nouvelle cartographie, pétrographie et géochimie, comprenant des analyses REE, indiquent une région plus étendue de granite de muscovite-biotite et moins de dikes d'alaskite qu'on ne le pensait auparavant, dans la région de Halifax-St. Margarets Bay. Lee roches de cette région ont été formées par le cristalisation fractionnfie de quartz, de plagioclase, de biotite, de zircon, d’ilmenite, d'apatite, et de la monazite. La présence de monazite dans l'assemblage de cristallisation fractionate est essentielle pour expliquer le fort épuisement du contenu d'élément terre-rare, et le fractionnement des éléments légers terre rare, qui ont été relevés dans ces roches. Elles ont été affectées par la recristallsation hydrothermale perméable et par des développements locaux de Druses pegmatitiques et par un complexe stratifé de veines à bordures greisen. Un complexe de veines stratifies, à bordures greisen s'est forme dans une partie du granite muscovite-biotite, au sud de Sandwich Point, et même si cette zone montre tous les traits caractéristiques de la minéralisation d'autres parties du batholithe, elle est stérile. [Traduit par le journal]

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Published

1986-04-01

How to Cite

Smith, T. E., Peck, D., & Holm, P. E. (1986). A Re-Appraisal of the Alaskite/Muscovite-Biotite Granite Suite of Halifax County, Nova Scotia. Atlantic Geoscience, 22(1). https://doi.org/10.4138/1600

Issue

Vol. 22 No. 1 (1986)

Section

Articles

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