Quantification of Single Fluid Inclusions by Combining Synchrotron Radiation-Induced μ-X-ray Fluorescence and Transmission

Abstract

Fluid inclusions represent the only direct samples of ancient fluids in many crustal rocks; precise knowledge of their chemical composition provides crucial information to model paleofluid-rock interactions and hydrothermal transport processes. Owing to its nondestructive character, micrometer-scale spatial resolution, and high sensitivity, synchrotron radiation-induced micro-X-ray fluorescence has received great interest for the in situ multielement analysis of individual fluid inclusions. Major uncertainties associated with the quantitative analysis of single fluid inclusions arise from the inclusion depth and the volume of fluid sampled by the incident beam. While the depth can be extracted directly from the fluorescence spectrum, its volume remains a major source of uncertainty. The present study performed on natural and synthetic inclusions shows that the inclusion thickness can be accurately evaluated from transmission line scans. Experimental data matched numerical simulations based on an elliptical inclusion geometry. However, for one nonelliptical inclusion, the experimental data were confirmed using a computed absorption tomography reconstruction. Good agreement between the imaging and scanning techniques implies that the latter provides reliable fluid thickness values independent of the shape of the inclusion. Taking into consideration the incident angle, the incident beam energy, the inclusion fluid salinity, and the transmission measurement stability resulted in errors of 0.3-2 microm on calculated fluid inclusion thicknesses.

Synchrotron micro-X-ray fluorescence analysis of natural diamonds: First steps in identification of mineral inclusions in situ

“…The μSXRF spectra were collected using a 7-element intrinsic Ge detector mounted at 90° to the incident beam (45° to the sample normal). This 45° incident angle to the sample is within the 40-60° range recommended for the optimal set-up of analytical μSXRF (Cauzid et al 2004). Spectral reproducibility was excellent among repeat μSXRF spectra.…”

“…Quantifi cation of the μSXRF data requires knowledge of the geometry of an individual inclusion and its position in the host mineral. These two parameters could be determined optically (Mavrogenes et al 1995;Rickers et al 2004) or extracted from the fl uorescence spectrum (Philippot et al 1998) and transmission line scans (Cauzid et al 2004). Concentrations of trace elements are then evaluated by reference to an external or internal standard (Mavrogenes et al 1995;Vincze et al 2004;Hansteen et al 2000) or by comparison with spectra simulated by a Monte Carlo routine .…”

Cryogenic Raman Spectroscopic Studies on Common Ore-forming Fluid Systems

“…Fluid inclusions give insight into the composition of mineralizing fluids and the physical and chemical conditions of mineralization during the trapping of fluids. In recent years, advances have been made in micro-analytical techniques that can be applied to the in situ analysis of fluid inclusions, including laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) [1][2][3][4][5], secondary ion mass spectrometry (SIMS) [6], particle-induced X-ray emission (PIXE) [7][8][9], and synchrotron X-ray fluorescence spectroscopy (SR-XRF) [9][10][11][12][13][14]. Most of these methods are destructive and semi-quantitative.…”

Fluids in geological processes — The present state and future outlook

“…Synchrotron-based studies allow not only elemental, but also speciation information to be retrieved from single fluid inclusions (e.g., Cauzid et al, 2004Cauzid et al, , 2007, and the method may be applicable even to opaque minerals (Cauzid and André-Mayer, 2009). …”