CANADA NATIONAL GEOCHEMICAL RECONNAISSANCE PROGRAM

National Geochemical Reconnaissance (NGR) stream-and lake-sediment and water surveys have been carried out by the Geological Survey of Canada both independently and with the provinces under various federal-provincial programmes since the early 1970s. These surveys, which use established methods and specifications for the collection, preparation, analysis and publication of the data, provide a systematic coast-to-coast geochemical database. Areal coverage to 1990 amounted to approximately 2 100 000 km2, representing 180 000 sites. Although the data have applications in resource evaluation, environmental studies, etc., their prime utilization is in aiding and stimulating mineral exploration. Excess sediment material that is not required for the initial analytical determinations has been stored for future use. Reanalysis of these samples by instrumental neutron activation analysis (INAA) provides usable data for a large number of elements (up to 20 new elements). The NGR surveys and the programme of archive reanalysis are supported by orientation and follow-up studies on specific geochemical problems and interpretative work on the existing geochemical database. These often have a direct impact on the regional surveys.