Comparison of different portable XRF methods for determining till geochemistry

Abstract

Three portable X-ray fluorescence (pXRF) methods were compared and tested in an exploration program using till in Sinoselkä, northern Finland. The use of one truck-mounted XRF unit and two handheld pXRF analysers were tested for basal till samples gathered using percussion drilling with a flow-through sampling bit. The datasets were compared to both conventional aqua regia based analyses and each other. The results prove that a correlation between the data generated by different pXRF methods was acceptable for some major (Ca, Fe) and most of the base metal elements (like As, Cr, Cu, Mn, Ni, Pb, Zn) in the Sinoselkä area. The pXRF analyses also correlate well with the aqua regia geochemical data of the same elements. Distribution of the elements was comparable to the lithological changes in the underlying bedrock that indicates a short glacial transport distance. It is also demonstrated that more than absolute values, the relative values and their changes are those which should be considered and carefully examined. The results reported here emphasize the usefulness of pXRF analysers in till geochemical exploration and demonstrate that they involve easy and fast methods to collect geochemical data for tracing sources of multi-metal mineralization. Furthermore, pXRF is applicable in gold exploration, although indicator elements like As, Bi, Cu, Mn and Sb have to be used instead of Au.