Lithogeochemical investigations were carried out in and around the Montauban polymetallic deposits of the Grenville Province, Quebec. A number of chemical criteria used to distinguish sedimentary and igneous protoliths for the ore host rocks were tested and found to be weak in their discriminating capabilities. Critically evaluated chemical criteria show that the protoliths for quartzofeldspathic gneisses, quartz-rich rocks, and host rocks were mainly siliceous sediments and intercalated carbonate lenses. Hornblende gneisses of the Montauban area are orthogneisses. They and other orthoamphibolite rocks in the study area have a tholeitic affinity. Incompatible element chemistry suggests that they were formed in an island-arc (including back-arc) environment. / Alteration associated with the Montauban Pb-Zn deposits is weak and has a narrow lateral extension with erractic chemical halos close to the ore-bearing zones. A CaO-rich zone extends up to 140 m laterally to the east from the calc-silicate ore zone, and an anomalous MgO zone extends on both sides of the cordierite-anthophyllite ore zone into the quartzofeldspathic gneisses. The cordierite-anthophyllite gneiss host rock is more anomalous in Zn, Pb, Cu and Au than the calc-silicate host rock. Erractic high concentrations of Zn and Au occur within the quartzofeldspathic gneisses close to both ore-bearing zones. Copper and Au occur at slightly greater depths than Zn and Pb within the deposits. / The Montauban Pb-Zn deposits were formed in a mainly sedimentary environment, probably by exhalative processes, and were metamorphosed to the almandine-amphibolite facies with the enclosing sediments.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.77170 |
| Date | January 1981 |
| Creators | Prabhu, Mohan Keshav. |
| 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 Geological Sciences) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000139263, proquestno: AAINL10290, Theses scanned by UMI/ProQuest. |
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