A FREEZE-SAMPLING TECHNIQUE FOR THE COLLECTION OF ACTIVE STREAM SEDIMENTS USED IN MINERAL EXPLORATION AND ENVIRONMENTAL-STUDIES

This paper compares freeze- and grab-sampling techniques for the colle ction of active stream sediments. statistical analysis indicates a sig nificant difference (p < 0.01) between the two techniques for all of t he 10 oxides and 21 minor elements analysed. The percent weight of oxi de and elemental concentrations obtained at over 122 sampling location s indicate that.freeze-sampling collects representative sediment sampl es. Fifty percent fewer freeze-samples are required per site in order to obtain representative estimates of the percentage oxide and element concentration in the sediment. In contrast, grab-sampling introduces a bias in the textural composition of the minus 125 mum (120 mesh or 3 phi) fraction, the sediment interval used for routine geochemical anal ysis, because of wash out and elutriation of finer fractions. The free ze-sampling technique is recommended for mineral exploration and basel ine environmental studies.