Quantitative PIXE analyses of single fluid inclusions in quartz crystals with a 1.92-MeV tandetron

Analytical errors in single fluid inclusion analyses by PIXE were investigated to evaluate the accuracy and detection limits of this type of analysis. Analytical errors due to the ellipsoidal approximation of the inclusion shape and the presence of a precipitated halite crystal in the inclusion were much smaller than the total analytical error. The major source of error in the quantification was the uncertainty in the determination of the inclusion depth, which can be minimized by using measurements of the Cl Kβ/Kα intensity ratio. The total analytical error was ±17% relative for most elements and ±40% relative for Cl. Detection limits of 15-40 ppm for elements with mass numbers 25-38 were achieved in analyses of ellipsoidal fluid inclusions (size, 50 μm × 30 μm × 30 μm; depth, 10 μm; bubble size, 15 μm; and NaCl solution, 10 wt%) in quartz, at an integrated charge of 1.0 μC and beam size of 50 μm × 50 μm. The trace-element compositions of single fluid inclusions in quartz crystals from a miarolitic cavity or from quartz veins within a granite body were also determined to investigate the chemical compositions of granite-derived fluids and compositional changes in the fluids during fluid movement in a granite body.