Talus fine sampling as a regional geochemical exploration technique in mountainous regions

Abstract

Abstract In areas of rugged topography, extensive and rapid dilution of metal-rich stream sediment with barren material can greatly shorten dispersion trains of base metals in drainage sediments. Poor definition of anomalies among stream data can also result from sampling an area of high background metal contents. Consequently, geochemical exploration requires a sample medium which will provide material that is more representative of underlying bedrock. In certain instances, talus fines meet this requirement. Talus fines are collected at regularly spaced intervals near the base of prograding deposits, possibly in conjunction with stream sediment and geological surveys. Sampling is completed more slowly than comparable drainage surveys, but still with relative ease. Sample collection is followed by analysis using routine analytical procedures. Comparison of Cu, Mo, Pb and Zn contents of complementary pairs of stream sediment and talus fine samples from cirques, and U- and V-shaped valleys in central British Columbia shows talus fine geochemistry more successfully outlines mineral occurrences than drainage geochemistry.