Mineralogical and isotopic relations in the Port Radium pitchblende deposit, Great Bear Lake, Canada

• Main Author: Jory, Lisle Thomas
• Format: Thesis
• Language: English
• Published: 1964
• Subjects: Canada; Great Bear Lake; Echo Bay; Hornby Bay; Cameron Bay
• Online Access: https://thesis.library.caltech.edu/4028/; https://thesis.library.caltech.edu/4028/1/Jory_lt_1964.pdf; https://thesis.library.caltech.edu/4028/2/Jory_lt_1964_Fig_3.pdf; https://thesis.library.caltech.edu/4028/3/Jory_lt_1964_Fig_4.pdf; https://thesis.library.caltech.edu/4028/4/Jory_lt_1964_Fig_5.pdf; https://thesis.library.caltech.edu/4028/5/Jory_lt_1964_Fig_6.pdf; https://resolver.caltech.edu/CaltechETD:etd-10112002-152503

NOTE: Text or symbols not renderable in plain ASCII are indicated by [.]. Abstract is included in .pdf document. This thesis integrates the data from field, petrographic, X-ray, and lead and uranium isotopic studies on the Port Radium pitchblende deposit, Great Bear Lake, Canada. The oldest rocks exposed are andesitic-dacitic bedded tuffs and flows of the Echo Bay group. Overlying detrital rocks of the Cameron Bay group were accumulated before intrusion of hypabyssal, dacitic porphyry bodies and granitic rocks. Sandstones of the Hornby Bay group lie unconformably on the above groups and on denuded granitic rocks. Folds are generally open in the Echo Bay and Cameron Bay groups; the Hornby Bay group is flat-lying. The Echo Bay group was metamorphosed to hornblende hornfels facies rocks, probably during intrusion of granitic rocks. Fault and fracture zones, most commonly striking northeasterly and dipping steeply north, were in places loci for the successive introduction of "giant quartz veins", diabase dykes, and complex vein mineralizations. In the development of the Port Radium deposit, six stages of metallic and non-metallic vein mineral deposition are recognized. Three periods of wall rock alteration are correlative with episodes of vein mineralization. Tuffs of the Lower Echo Bay subgroup are the predominant host rocks to the ore mineralization. Localization of the pitchblende is attributed to physical factors. Diabase sills, intruded after development of the Port Radium deposit, were fractured during late-stage movements on the veins. An age of 1820[plus or minus] 30 million years is assigned to a granitic rock at Port Radium on the basis of the lead-uranium isotopic analyses of seven zircon fractions. This sets a lower limit on the age of the Echo Bay and Cameron Bay groups and an upper limit on the age of Hornby Bay group and diabase dykes. In the zircon fractions, uranium and radiogenic lead concentrations increase with decreasing average grain size. All fractions show the discordant age pattern Pb ...