Abstract

The Temiscamie Fe formation of the Lake Albanel iron range in Mistassini territory, Quebec, is approximately 700 ft. thick and is divided into 6 members on the basis of lithology. The principal Fe-bearing minerals are siderite, magnetite, hematite, and iron silicates. A bulk chemical analysis of the Fe formation, excluding the thin lower argillite member, shows 29% of Total Fe and is similar in many respects to the average compositions of Fe formations of the Mesabi, Cuyuna, and Gogebic districts. The Temiscamie Fe formation is overlain by the Kallio slate and is underlain by the Boulder Bay quartzite and the upper and lower Albanel dolomites, the sequence constituting the Mistassini group. These rocks are underlain by sediments of the Papaskwasati group, which rest with angular unconformity on a basement of folded sediments and volcanics of the Sam Gunner group. The latter was earlier intruded by igneous rocks of the Takwa complex. The Papaskwasati and Mistassini sediments are relatively unmetamorphosed. They dip to the SE. and abut against high-grade metamorphic and igneous rocks of the Grenville subprovince along the Mistassini fault. The names Boulder Bay quartzite, Sam Gunner group, and Takwa complex are introduced. The Temiscamie Fe formation, on the basis of lithology, has been correlated with the Fe formation of the Labrador trough. Results of radioactivity dating are inconclusive but indicate the possibility of the Temiscamie Fe formation being younger than the Huronian Fe formations of the Lake Superior district. At the same time the radioactivity dates from northern Quebec and Labrador suggest a complicated geologic history for this region. Effects of the Grenville orogeny have been superimposed on rocks that were involved in 2 earlier major orogenies.

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