USE OF GLACIAL GEOLOGY FOR MINERAL EXPLORATION

Glaciers erode, transport, and deposit debris systematically, and by applying this basic tenet, geologists use glacial geology as a prospecting tool, a concept commonly known as “drift prospecting,” to search for aggregate resources, industrial minerals, base metals, precious metals, and gems. Drift prospecting is commonly unavoidable in glaciated terrain that lacks significant bedrock outcrop, such as the Canadian Shield. Plumes of ore minerals can be found in a variety of glacial deposits and landforms, including till, glaciofluvial sediment, moraines, and eskers. The key to tracing the plumes upglacier to the source lies in carefully delimiting the size and shape of the plume, and through the provenance of the indicator boulders and minerals, identifying the lithology of the bedrock target. Field techniques include air photo interpretation, mapping glacial deposits and landforms, lithologic identification of large clasts (“boulder tracing”) and indicator minerals, geochemical analysis of the silt-plus-clay fraction of soil horizons. Airborne and ground geophysical surveys may provide useful supplementary information. These techniques have resulted in the discovery of base metal and precious metal deposits, and in the early 1990s, the world-class diamond deposits in kimberlites of Nunavut (northern Canada). Other examples to be presented include gold and barite mineralization (Matachewan, Ontario), kimberlites (Northern Michigan), and uranium (Nunavut, Canada).