Uranium and Thorium Occurrences on the North Shore of the Gulf of St. Lawrence

CIM Bulletin, 1970

A. B. BALDWIN, Chief Geologist, Cerro Mining Company of Canada Limited, Toronto, Of.ltario

Uranium and thorium mineralization occurs at several localities in eastern Quebec along the north shore of the Gulf of St. Lawrence. The main occurrences are near Sept-Iles, Baie Johan Beetz, Romaine and St-Augustin river. Mineralization occurs mainly as disseminated uraninite, uranothorite, uranothorianite, monazite and minor zircon and allanite. Yellow to orange oxidation products are observed along fracture planes of the uranium-bearing deposits to a depth of a few feet. Magnetite, biotite and smoky quartz have a distinct tendency to accompany the radioactive minerals. The host rocks include white to pink pegmatite, pink granite and also, in the case of the Romaine and StAugustin River occurrences, cream to grey plagioclaserich, well foliated paragneiss and migmatite. Radioactivity near secondary structures, such as fractures and joint planes, indicates some reconstitution of radioactive minerals. The North Shore of Quebec is the northeast extension of the G nville sub-province. It is also a uranium-thorium metallogenic province.
Keywords: biotite, gneisses, granite, pegmatite, plagioclase, Granite, Granites, mineral, minerals, North, Pegmatite, Pegmatites, Rock, Rocks