The composition and structural features of feldspars from the rocks of Mounts Royal, Bruno, Johnson, St. Hilaire, Rougemont, Yamaska, Shefford and Brome have been studied by optical and x-ray diffraction methods. Extensive diffraction work did not disclose the presence of highly disordered feldspars (high comparative forms). However, the plagioclases of these rocks belong to a distinct series whose order-disorder relations are in agreement with the geological setting of the intrusives and would classify the rocks as hypabyssal rocks (shallow seated rocks). The alkali feldspars of the Monteregian rocks belong to the low-albite--orthoclase series. The presence of this series of alkali feldspars and the absence of feldspars of the low-albite--microcline series is a characteristic of these rocks that is regarded to be a consequence of their cooling history. The rate of cooling of the igneous masses and the annealing of the rocks under predominantly dry conditions are thought to have been the principal factors responsible for the incomplete ordering of the feldspars. The trends of crystallization and the interrelations between the rock types are discussed on the basis of the compositional data obtained on the feldspars. A qualitative diagram for pressures of approximately 1000 bars has been presented to explain the paragenesis of the feldspar associations encountered in the Monteregian Rocks.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.113745 |
| Date | January 1962 |
| Creators | Pouliot, Gaston. |
| Contributors | Stevenson, J. (Supervisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy. (Department of Earth Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: NNNNNNNNN, Theses scanned by McGill Library. |
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