Marcela Barrera-Cortes, PhD
M. Barrera-Cortes1, D.R. Lentz1, K.G. Thorne2
1Department of Earth Sciences, University of New Brunswick, Fredericton, New Brunswick, Canada
2New Brunswick Department of Natural Resources, Fredericton, New Brunswick, Canada
Tungsten (W) is essential for hard metal alloys used in cutting and drilling equipment, as well as in heat-resistant coatings for green technologies and defence applications. Its properties cannot be substituted by other metals, and with China producing nearly 80% of global supply and holding ~52% of reserves, W is considered a critical mineral. Although portable X-ray fluorescence spectrometry (pXRF) is widely used for rapid geochemical assessment in various metallogenic systems, its application in granophile mineralization (W–Sn–Mo) remains limited due to the poor analytical performance for W. Nevertheless, several elements detectable by pXRF can serve as reliable pathfinders for W-enrichment. This study evaluates the behaviour of these pathfinders in differentiating W-bearing veins from weakly mineralized or barren host rocks across six deposits and occurrences located in the Central and Southern Plutonic Belt of New Brunswick. These systems are associated with Early to Late Devonian granitic cupolas. Diamond drill cores archived in the New Brunswick government core storage facilities were examined, and a dataset of 220 pXRF measurements was collected using an Olympus Vanta analyzer in soil mode, employing a 6-minute total integration time on flat, dry rock slabs. Calibration was completed with four Certified Reference Materials analyzed repeatedly. Preliminary results reveal three analytical performance groups: (i) elements with small bias and strong goodness of fit (>0.9), including As, Mo, Th, Pb, and Sn; (ii) elements with moderate bias and acceptable goodness of fit (Fe, Cu, Zn, Rb, Bi); and (iii) elements showing extremely poor behaviour, typically due to concentrations near the instrument’s detection limit (LOD) or large intercept values (instrument offset). These limitations indicate that pXRF should be used primarily as a qualitative vectoring tool rather than for quantitative W assessment. Multivariate analyses show consistent elemental patterns across deposits. Bi, As, and Mo are effective discriminators of W-mineralized veins, whereas Pb, Zn, and Cu are more closely linked to altered metasedimentary host rocks. These associations reflect mineralogical controls: Bi–As–Mo enrichments correspond to sulphide–wolframite vein assemblages, while Pb–Zn characterizes host-rock sulphides. Despite the masking effect of the metasedimentary rocks, principal component analysis (PCA) successfully differentiates sulphide veins from W-bearing veins based on elemental loadings, demonstrating the value of pXRF as a qualitative support tool during drill-core logging and early-stage exploration.