Review of regional lake sediment geochemistry methods for mineral exploration in glaciated terrain

This paper reviews the application of lake sediment sampling in the recently glaciated terrain (last 100,000 years) of Canada where organic-rich lake sediments have been accumulating in lakes since deglaciation during the last 10,000 or so years. Lake sediment is a useful exploration sample medium for detecting geochemical dispersion from mineralized bedrock and/or metal-rich glacial dispersal trains. The method is used in areas of low to moderate topographic relief and poor to moderately developed drainage systems in the Canadian Shield and some parts of the Appalachian regions of Canada, as well as in low relief areas in the Canadian Cordillera that are covered by thick glacial sediments and have abundant lakes. Government organizations and exploration companies have conducted more than 100 lake sediment surveys across Canada since the 1970s and some of these are used to illustrate key concepts. The paper summarizes protocols for execution and interpretation of lake sediment surveys, serving as a practical guide for both the mineral exploration industry and government agencies. Methods for sample collection, processing, and analysis, quality assurance/quality control (QA/QC) procedures, and data reporting are reviewed. Much of the information presented here is based on the methods used by the Geological Survey of Canada, British Columbia Geological Survey, and Ontario Geological Survey to conduct lake sediment surveys in Canada.