Resolution of geochemical and lithostratigraphic complexity: a workflow for application of portable X-ray fluorescence to mineral exploration

Abstract

Portable X-ray fluorescence (pXRF) technology can be used to collect large amounts of multi-element data rapidly at relatively low cost and has been widely embraced within the minerals industry. However, to date, it has been difficult to compare data-sets collected by different users or at different times because there is no standardized approach to the collection of these data. The absence of information on standardization and calibration procedures raises concerns about a lack of internal consistency within these data-sets and precludes comparison of different data-sets. This paper seeks to address this issue by developing a workflow for the collection of pXRF data in an exploration or mining setting. Two case studies highlight the robustness and possible applications of pXRF data collected following QA/QC protocols. A good correlation between conventional laboratory analyses and pXRF data is demonstrated through comparison of analysis methods for a drill-hole at the Plutonic Gold Mine, Western Australia, and fine-scale lithostratigraphic variation is recognized in pXRF data collected on grade control pulps from a drill fan at the Agnew Gold Mine, Western Australia. The Agnew data precision is sufficient to distinguish alteration signals from background lithology, and to discern which alteration signals are associated with gold mineralization.

A review of pXRF (field portable X-ray fluorescence) applications for applied geochemistry

“…Despite these limitations, pXRF data have been used for demonstrating exploration results. This was made possible through the application of robust procedures and QA/QC schemes such as those recommended by Hall et al (2013), Fisher and Gazley (2014) or . A critical review of expedited field practice, suitable for reconnaissance but inadequate for reporting, was given by Durance et al (2014), who recommended the use of site-specific calibrations rather than general purpose CRMs.…”

“…It does not substitute laboratory analyses (Ridings et al, 2000), but it offers a wide range of possibilities for site investigations that could not be provided by laboratory analyses for an acceptable cost (Higueras et al, 2012;Paulette et al, 2015). pXRF is highly recommended for extensive field surveys and lab sample selection, using a robust protocol (West et al, 2015;Fisher et al, 2014) and to complement these surveys by systematic control analyses in the laboratory.…”

An innovative optical and chemical drill core scanner

“…Portable/handheld XRF instruments are gaining popularity and have been applied widely and successfully to analyse drill cores in a non-destructive way (e.g. Gazley et al, 2011Gazley et al, , 2012Fisher et al, 2014;Le Vaillant et al, 2014;Ross et al, 2014). Advantages of the new instrument over handheld XRF instruments are a better and more representative coverage (continuous scanning vs. point analyses), reduced labour, standardised analytical conditions, integrated routines, and advanced data handling.…”

Application of portable X-ray fluorescence analysis to characterize dolerite dykes at the Plutonic Gold Mine, Western Australia

“…From the Plutonic dataset of all the dolerite samples that had been analysed from the area of the Paris dolerite were split out (n = 210). This dataset was collected on pulverized core and standardized using the site-specific matrix-matched standard PLU-1 (see Fisher et al (2014) for expected values). Plotting Ti v. Zr data effectively discriminated dolerite populations at a mine-scale with clear separation in Zr concentrations but some overlap in Ti concentrations (i.e.…”