Geochemical studies of snow over mineral accumulations under conditions of their overlap by sedimentary rocks of the platform cover.

In geochemical exploration, the seasonal snow cover is a convenient natural material for identifying under deep covered mineral accumulations. Snow has shielding and accumulating properties sufficient for the occurrence of dispersion of geochemical halos. The snow horizon of geochemical sampling is protected from atmospheric and landscape factors of replenishment of its chemical composition for most of the winter. The filtrate of snow melted water is cleaned of large-sized solid material, and chemical compounds are in the dissolved and finely dispersed solid phase of submicron dimension. Therefore, in terms of the physical and chemical properties of the analyzed substance, snow geochemical survey is close to selective methods. Test surveys were carried out on single profiles of snow sampling at two ore occurrences (Au, Pb-Zn) and an oil field within the West Siberian plate. Concentrations of a wide range of chemical elements in snowmelt water filtrate were determined by the ICP-MS method. As a result of statistical processing of geochemical data, a low variability of concentrations of chemical elements has been established. Correlation and regression analyzes demonstrate the presence of linear dependences in the distribution of trace elements, which reflect the ability of elements to form easily soluble and hardly soluble occurrence forms. The variability of the local geochemical background is mainly due to the content of hardly soluble phases that entered the snow layer during its deposition on the ground. Presumably, they are represented by particles of aeolian dust, needles and scales of tree bark captured by snow from tree and shrub crowns. In the area of study with high heterogeneity of elementary landscapes, the influence of this factor is comparable in amplitude to the contrast of superimposed geochemical halos. Normalization of the concentrations of trace elements by the sum of rare earth elements (REE) allows to strengthen the useful geochemical signal. Geochemical anomalies detected in snow in space quite accurately coincide with the position of mineral deposits buried the platform cover terrains, and also find confirmation in the chemical composition of soils and soil air. The good potential of snow metallometric surveying for prospecting of deep-seated mineral resources needs to be confirmed by studying the vertical and lateral migration of chemical elements in the snow cover. • Geochemical snow survey is informative when searching for buried mineral resources • Correlation associations of chemical elements indirectly reflect their easily soluble and hardly soluble occurrence forms • The concentration levels of rare earths are associated with the introduction of soil particles into the snow • Normalizing the concentrations of trace elements by the amount of REE is useful for mapping of superimposed halos [ABSTRACT FROM AUTHOR]