Date of Award
Master of Science (MS)
D. Perkins, III
Four areas are considered in this study. In Ontario, north-south traverses were made along Highway 599 between Savant Lake and Central Patricia, along the Vermilion River road (40 kilometers northeast of Sioux Lookout) and along Highway 105 between Vermilion Bay and Ear Falls (Fig. 3). The fourth area is centered at Bird River, northeast of Lac du Bonnet, Manitoba. The study areas are located in the Uchi, English River and Wabigoon Subprovinces.
The traverse along Highway 599 between Savant Lake and Central Patricia crosses the three subprovinces (Fig. 3). Pelites in the eastern Lake St. Joseph area (Uchi Sub province) and Wabigoon Subprovince indicate that metamorphic conditions were 2-4 kb and 425-600°C (Fig. 3).
The Vermilion River logging road crosses the English River Subprovince and has four lithologies that are useful in determining metamorphic conditions: hypersthene ± clinopyroxene granulites, biotite, biotite-garnet, and biotite-garnet-cordierite paragneisses (Fig. 3). Garnet cordierite geobarometry yielded pressures of 3.8-6.S kb. The metamorphic temperatures increased slightly for the four lithologies: biotite gneisses (<610-650°C), biotite-garnet gneisses (610-670°C), and granulites and biotite-garnet cordierite gneisses (650-750°C) .
The Red Lake road traverse crosses 3-4 km of the extreme northern Wabigoon Subprovince and approximately 90 km of the English River Subprovince (Fig. 3). The rocks of the North and South Domains of the English River Sub province were probably metamorphosed at 650-750°C and 5-7.5 kb.
The Bird River greenstone belt is located approximately 200 km northeast of Winnipeg in the English River Subprovince (Fig. 3, 34). Metamorphic temperatures were usually 450-600°C and were estimated from metamorphic assemblages. The common occurrence of andalusite in the pelites suggests that metamorphic pressures did not exceed 4 kb in most of the belt. Carbonate-rich rnetabasites at the Bird River Bridge may have had Xco2 values that exceeded 0.15.
Two tectonic models for the formation of the Uchi, English River, and Wabigoon subprovinces were derived from the pressure and temperature data, along with geophysical and structural information from other studies. A non subduction model assumes that Archean plates were too thin and hot to be subducted (Fig. 43-47). The plate tectonics model includes subducting plates and is based on the work of Langford and Morin (1976) (Fig. 49).
Henke, Kevin R., "Archean metamorphism in northwestern Ontario and southeastern Manitoba" (1984). Theses and Dissertations. 134.