A funnel-shaped alteration pipe in Archean tholeiitic to transitional rhyolite and andesite underlying massive Zn-Cu sulphide ore at the Norbec mine in northwestern Quebec was outlined from drill core samples. Geochemical parameters, including mass changes and mobile element ratios were used with normative alteration mineralogy and thin section petrography to determine the extent of the alteration. The alteration was initially characterised by a peripheral zone of sericite-chlorite-quartz and a central chlorite-quartz zone. Isochemical metamorphism of the alteration pipe within the contact aureole of the Lac Dufault stock has converted these assemblages to cordierite-anthophyllite-biotite bearing rocks. / Bulk oxygen isotope data for the altered rhyolite suggest that the Norbec deposit formed at temperatures between 200$ sp circ$C and 300$ sp circ$C, with highest temperatures in the central chloritic zone of the alteration pipe. Calculations using SiO$ sb2$, K and Fe solubilities in typical sea-floor hydrothermal fluids suggest that water/rock ratios of 250 to 900 were necessary to introduce the added mobile elements to the alteration pipe.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.56759 |
| Date | January 1992 |
| Creators | Shriver, Noëlle |
| 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 | Master of Science (Department of Geological Sciences.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001318392, proquestno: AAIMM80478, Theses scanned by UMI/ProQuest. |
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