A freeze-sampling technique for the collection of active stream sediments used in mineral exploration and environmental studies

Abstract

This paper compares freeze- and grab-sampling techniques for the collection of active stream sediments. Statistical analysis indicates a significant difference (p<0.01) between the two techniques for all of the 10 oxides and 21 minor elements analysed. The percent weight of oxide and elemental concentrations obtained at over 122 sampling locations indicate that freeze-sampling collects representative sediments samples. 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 μm (120 mesh or 3φ) fraction, the sediment interval used for routine geochemical analysis, because of wash out and elutriation of finer fractions. The freeze-sampling technique is recommended for mineral exploration and baseline environmental studies.