Tracing Ore Boulders as a Prospecting Method in Canada

CIM Bulletin, 1958

A. DREIMANIS

Tracing of 'float' against the latest ice-flow directions ha!' led to or assisted in discoveries of several mineral deposits in Canada at least since 1891, e.g., fluorite and corundum in eastern Ontario, Steeprock and Josephine iron ore in western Ontario, Malartic, Fisher-Quebec, and Lamaque gold ore, and Vendome zinc ore, in western Quebec, Sullivan zinc and lead sulphides in British Columbia, Orvan Brook or New Calumet sulphide deposit in New Brunswick, Lynn Lake nickel sulphide deposit in Manitoba, etc. Pebbles or ore boulders whose source has not yet been found include diamonds in the Great Lakes region and sulphides in several localities in Ontario and Quebec. Complexity of transport of ore boulders, including non-glacial transport, may be the explanation. Tracing of ore boulders requires knowledge of the Pleistocene history of each particular area (ice flow directions, their changes during glacial oscillations, existence of preglacial lakes with ice-rafted boulders, later interference by streams, lakes, mass movements). Important also is distinction of till from similar non-glacial deposits and knowledge of the bed-rock geology. Quantitative methods, e.g., pebble counts, may 1be applied while tracing magnetite, hematite, or goethite. Fragments of sulphide ores are less abundant in indicator trains, and quantitative methods are less suitable for tracing them. Heavy-mineral investigations may give good results for minerals resistant to weathering. Geochemical methods are of value only in the vicinity of ore deposits

Keywords: Abitibi County, Quebec, Eastern Ontario, hematite, Iron Ores of Nipissing, nepheline syenite, Ontario, Ore, Ores, pebbles, sulphide, Sulphides, Till, Trains