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Since 2009 all underground face samples and diamond-drill core samples at the Plutonic Gold Mine (Plutonic), Marymia Inlier, Western Australia have been analysed by portable X-ray fluorescence (pXRF) following a systematic approach. This method is rapid and cost-effective and provides analyses of a large suite of chemical elements which can be used to characterize lithology and alteration. The delivery of a comprehensive workflow for sample preparation, analysis, results correction, and rapid processing enabled a quantum leap in the way mine geologists use geochemistry in modelling the ore body. Interpretation of the mine-site dataset of over 200 000 multi-element analyses has resulted in significant improvements in the understanding of the Plutonic deposit. In this contribution, we review how our understanding of Plutonic has been significantly improved through the use of pXRF geochemical analyses. Incorporation of pXRF data into routine geological modelling at Plutonic has resulted in improved confidence in the models of the ore bodies themselves and late-stage dolerite intrusives. It has allowed better management of milling processes through the development of metallurgical proxies and for significant insights into the role of stratigraphy in controlling the location of gold mineralization. We highlight the potential that a systematic approach to collecting pXRF data can have in a mining environment. These same techniques could be adapted and used in other mine and/or exploration settings. [ABSTRACT FROM AUTHOR]

Abstract: Stratigraphy, structure and host-rock chemistry are dominant controls on the location of Au in Archaean greenstone-hosted Au deposits, but the stratigraphy in such deposits is seldom obvious due to the monotonous nature of the host rocks or pervasive alteration associated with Au mineralisation. Portable, hand-held, X-ray fluorescence (pXRF) spectrometry provides a method to rapidly collect large amounts of whole-rock geochemical data that can yield new insights into both stratigraphy and Au localisation. Here we present results of pXRF analyses of samples from a representative section through Au-mineralised amphibolite-facies metabasaltic rocks at Plutonic Gold Mine, Western Australia. These data illustrate a geochemical stratigraphy in which individual lava flows can be identified on the basis of element concentrations. The most evolved basalts are at the structural base of the succession, and the least evolved at the top of the sequence, confirming previous geochemical interpretations and textural evidence that the sequence is overturned, and demonstrating for the first time that the presented section does not involve significant structural repetition. In conjunction with Au assay data, the pXRF data reveal that Au commonly occurs along basalt flow boundaries. The elemental concentration data clearly demonstrates for the first time the stratigraphic control on Au mineralisation that is not readily apparent at the macroscopic level. The methods described in this paper are readily applied, and have the potential to enhance the understanding of otherwise unclear stratigraphy and its control on mineralisation in many different types of deposits worldwide. [Copyright &y& Elsevier]