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Biogeochemistry |
Geological Survey of Canada (Emeritus), 9860 West Saanich Road, Sidney, British Columbia V8L 4B2, Canada
This review article focuses on field methods in biogeochemical exploration and is based largely on the author’s experience. Consideration is given to reasons for applying biogeochemical methods as alternatives or supplements to other surficial sampling media that can be used in the exploration for mineral deposits in glaciated terrain. Extensive root systems can absorb metals from the substrate and integrate the geochemical signature of large volumes of sediment, groundwater and sometimes bedrock, thereby providing a more representative reflection of the chemical environment than that obtained from some other media. Sampling methods and precautions that should be taken are outlined. Variables that govern plant chemistry include the heterogeneity of composition among plant species and plant tissues, and the modifying effects of the seasons and contamination from external sources. Studies indicate that biogeochemical methods can provide a more proximal indication of concealed mineralization than the distal indications typical of till geochemistry programmes. Consequently, comparisons of till and biogeochemical data can help to define vectors toward mineralized sources such that the two methods are complementary.
