Snow in mineral exploration - Examples and practices in glaciated terrain

Although the origin of the snow is atmospheric, heat and gasses coming from underlying soil affect the concentration of hydrocarbons and elements in snow. For testing the use of snow in geochemical exploration, a test campaign was carried out in three different mineralization types in northern Finland: Au-Co, P-REE and Cu mineralizations. The snow samples were collected from the bottom of snow cover in two consecutive years. Two methods for analysing geochemical signatures of mineralized bedrock were applied to these snow samples: Spatiotemporal Geochemical Hydrocarbons (SGH) and ultra-trace elements determination by single collector high resolution inductively coupled plasma mass spectrometry (SC-HR-ICP-MS). The SGH method is based on detection of the hydrocarbons that are decomposition products of bacteria that use specific mineralization in their growth phase. In the case of the inductively coupled mass spectrometry, the content of a wide range of elements was determined. The results of both methods showed that the traces inherited from the tested mineralization can be observed in snow. The SGH signature located the Au-Co mineralization using an Au template and the Cu mineralization using a Cu template, although low signal repeatability may be the weakness. The response to the P-REE mineralization with a Polymetallic template was unclear. An improvement was achieved by reinterpreting the result with a customized template for REE. In addition, the repeatability with reinterpreted results showed similarities in the results between the sampling rounds. In the case of the SC-HR-ICP-MS method, results for several elements (e.g. As, Cu, Fe) showed a clear response over the mineralized zones for all three mineralization types. Mineral exploration would benefit using of snow as sampling material: this activity leaves virtually no footprint. Further studies are needed to improve the confidence and reliability in the use of snow as a sampling medium in mineral exploration.