Field-portable x-ray fluorescence spectrometer use in volcanogenic massive sulphide exploration with examples from the Touleary occurrence (MINFILE Occurrence 115O 176) in west-central Yukon

Field-portable x-ray fluorescence analysers (pXRF) are becoming a common tool in the savvy mineral explorer’s tool kit. Benefits include portability and ease of use, real-time acquisition of XRF data with minimal processing, immediate availability and analysis of data in the field, and a reasonably large number of elements that can be measured reliably. The findings indicate that data for 15 elements obtained with an Innov-X Omega pXRF analyser (2010 version) correlate well with lithogeochemical whole-rock analyses with R² values generally =0.7. The difference in elemental abundances between pXRF analyses of thin section off-cuts (a proxy for drill core) and pulps from the whole-rock analyses are generally ± 35%, indicating that no sample preparation is needed for the rock samples analysed in this study. The uncorrected pXRF values of some elements can be very similar to whole-rock analytical abundances; however, it is recommended that uncorrected pXRF data only be used semi-quantitatively, such as for downhole elemental plots in which relative patterns or trends are more informative than individual data points. For more sophisticated plots such as those combining elements into ratios to form alteration indices, corrected pXRF data should be used. The pXRF data are also adequate for construction of simple volcanic composition plots that can be used to aid in identification of protolith compositions of altered samples. The pXRF is well suited to volcanogenic massive sulphide exploration as the analytical data obtained from drill core (using thin section off-cuts as a proxy) are comparable to whole-rock analyses and the range of immobile and mobile, major and trace elements should be versatile enough for most exploration programs. However, pXRF shouldn’t be viewed as a replacement to traditional whole-rock geochemical methods.