Mineral Deposits Related to Maior Structures in the Precambrian of Manitoba
J. F. Davies Chief Geologist, Mines Branch, Manitoba Dept. of Mines & Natural Resources, Winnipeg, Man.
A review is presented of the fundamental differences between the Superior and Churchill geologic provinces. Structure, lithology, grade of metamorphism and a single recent age determination suggest that the Flin Flon - Snow Lake and Lynn Lake belts are remnant blocks of originally Superior rocks lying within the Churchill province. Major mineral belts occur along the main boundary between the Superior and Churchill provinces (the Thompson - Moak Lake nickel belt) and within the remnant Superior blocks inside the Churchill province (Flin Flon - Snow Lake and Lynn Lake). During the Hudsonian orogeny, metamorphic gradients must have existed across the Churchill-Superior boundary and between the remnants of Superior rocks and the enclosing gneisses of the Churchill province. It is possible that not only the unusual nickel deposits of the Thompson belt but also the base metal deposits of the Flin Flon - Snow Lake and Lynn Lake districts are due to redistribution, or diffusion and migration of metals to areas of lower-grade metamorphism during the Hudsonian orogeny. The southern edge of the Flin Flon - Snow Lake remnant and its intersection with the Thompson structure lies beneath a relatively thin mantle of Palaeozoic rocks. This should constitute a fertile area for exploration. Hudsonian ages are found in places throughout the Superior province and it is probable that Hudsonian activity has affected, to some extent, many parts of the Superior province. Those areas where superimposed orogenies are suspected merit further study. Other examples of such areas include the boundaries between the Palaeozoic and Precambrian southwest of Hudson Bay and along the northwest-trending strip paralleling Lake Winnipeg. In both these localities, major Precambrian discontinuities are suggested by abrupt changes in geologic trends. The depth to the Precambrian in the areas of interest ranges from 0 to 750 feet
Churchill Province, Flin Flon, Flin Flon, Lynn Lake, Nickel Belt, Palaeozoic, Precambrian, Manitoba, Precambrian, Rock, Rocks, Structure, Superior Province, Volcanic, Volcanics