Mode of Uranium Occurrence in a Migmatitic Granite Terrain, Baie Johan Beetz, Quebec

CIM Bulletin, Vol. 70, No. 780, 1977

Marcelle A. Hauseux, At time of writing with — McGill University, Montreal, Que., Now with — Denison Mines Limited, Exploration Division, Toronto, Ont.

The Turgeon Lake granite lies 5 miles north of Baie Johan Beetz, Quebec, at the eastern margin of the Grenville Province. The rocks are classed as granites, granulites, quartzites, biotite schists and gneisses, and amphibolites. The granite's uraniferous character is manifested by phosphuranylite, uraninite, and metamict zircons associated with magnetite. Field anomalies occur in irregular pods, conformable with the tectonic foliation, in bands roughly paralleling sedimentary bedding. Associated features diagnostic of uraniferous granite are smoky quartz, brick-red feldspar, magnetite and a coarse to pegmatitic grain size. The granite is chemically and physically heterogeneous. Metasediment-granite contacts are diffuse or sharp, and usually conformable to bedding. The regional foliations within all rock types are coherent, and sedimentary structures are often preserved within both metasediments and granite. Autometasomatism probably was a strong granitization agent. A uranium reconcentration into fold-axial zones from original sediments which have been highly granit-ized during at least two phases of folding is suggested from the available data.

Keywords: Turgeon Lake granite, Baie Johan Beetz, Geology, Petrology, Ore mineralogy, Petrochemistry, Mineral deposits, Migmatites, Uranium, Granites.