DYNAMIC ANALYSIS - ONLINE QUANTITATIVE PIXE MICROANALYSIS AND ITS USE IN OVERLAP-RESOLVED ELEMENTAL MAPPING

General PIXE microanalysis benefits from the rapid extraction of quantitative results. The microanalysis of minerals demands continuous feedback on mineral composition in order to monitor changing zoning profiles, or else to detect the presence of inclusions or simply to confirm the identification of grains under analysis. Hence, we have developed a spectral decomposition transform that closely approximates the time-consuming nonlinear least-squares method. The transform can be performed in live time to obtain continuously updated quantitative PIXE analyses as the data accumulate. A spinoff from this dynamic analysis approach is the ability to accumulate on-line PIXE elemental maps that are inherently overlap-resolved and background-subtracted. This paper describes the dynamic analysis method, demonstrates its effectiveness and shows an application of the method in geology to project out true elemental maps of trace Au in a study of polished sections from the Emperor gold-telluride deposit in Fiji. The method produced Au maps that effectively rejected overlapping peaks from Zn and As present in inclusion phases and as minor elements in the pyrite, and hence revealed the real distribution of Au.