The Cadillac mines are in the southern part of the Abitibi Greenstone Belt, one of the largest continuous units of the Superior Geologic Province. The belt extends for 760 km. over a width of 160 km. from the Grenville Province in the east to the Kapuskasing Gneiss Belt in the west. It is characterized by a number of elongate mafic to felsic volcanic complexes flanked by broad linear bands of metasedimentary rocks and ultramafic to mafic metavolcanic rocks. Numerous pre-, syn-, and post-tectonic plutons are present.
The geology of the Cadillac-Rouyn region is characterized by lenticular zones of Archean metavolcanic rocks of the Kinojevis, Blake River and Malartic Groups, separated by elongate bands of metasedimentary rocks of the Caste Formation and Kewagama and Cadillac Groups. Pre-, syn-, and post-tectonic granitoid intrusions are also present and all lithologies are cut by late, northeast-trending, Proterozoic diabase dikes.
The Porcupine-Destor Fault and the Larder Lake-Cadillac Fault are the main structural features of the area. They strike east/west to west-northwest/east-southeast and are subvertical. In the last decade, conflicting views on the genesis of these faults have been presented. Dimroth et al. (1982) have suggested that these structures are essentially dip-slip growth faults with dominantly normal movement. An alternative explanation, provided by Hubert et al. (1984), proposed that these faults were transcurrent (strike-slip) faults that were part of a system of wrench fault tectonism.
Stratigraphic interpretation of the area has also been the subject of much debate. Proposed stratigraphic columns from Table 1 lead us to conclude that those relationships are presently unknown; correlation across the major fault zones is the major difficulty. (For more information, readers are referred to the authors mentioned in the table.)
Regional metamorphic grade is low and most mineral assemblages are representative of the lower to upper greenschist facies (Jolly, 1976).
-REFER- Goodwin, A.M. and Ridler, R.H., 1970, The Abitibi orogenic belt, in Baer, A.J., ed., Basins and geosynclines of the Canadian Shield: Geological Survey of Canada., Paper 70-40, p. 130. Dimroth, E., Emreh, L., Rocheleau, M. and Goulet, N., 1982, Evolution of the south-central segment of the Archean Abitibi Belt, Quebec. Part 1: Stratigraphy and paleogeographic model: Canadian Journal of Earth Science, V. 19, p. 1729-1758. Hubert, C., Trudel, P., and Gelinas, L., 1984, Archean wrench fault tectonics and structural evolution of the Blake River Group, Abitibi Belt, Quebec: Canadian Journal of Earth Science, V. 21, p. 1024-1032. Jolly, W.T., 1978, Metamorphic history of the Archean Abitibi Belt, in Fraser, J.A. and Heywood, W.W., eds., Metamorphism in the Canadian Shield: Geological Survey of Canada, Paper 78-10, p. 63-77.
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