X-ray fluorescence micro-tomography of an individual fluid inclusion using a third generation synchrotron light source

Abstract

The aim of this study was to establish the feasibility of obtaining 3D elemental images of fluid inclusions, which consist of multiphase and irregular objects trapped in a host mineral. These experiments are based on the fluorescence micro-tomography technique, which combines X-ray fluorescence measurements and 2D tomographic reconstruction algorithms. For this purpose, multiphase aqueous fluid inclusions were synthesized in fractured quartz crystal within gold capsule at high temperature and pressure. A single fluid inclusion was isolated in a tiny quartz parallelepiped, polished on all its faces. On the basis of the parallel collection technique, the sample was successively scanned vertically over a few hundred micrometers, in steps of 3 μm and with an acquisition time of 1 s/point, and rotated by an angle of 2°. The 2D projection images, which consist in relative elemental concentration regions, provide the size and the location of the fluid inclusion as well as the elemental location and combination. By iterating the procedure along the horizontal rotation axis, full 3D elemental images can be obtained.