In situ X-ray absorption spectroscopy using the FAME autoclave: a window into fluid-mineral-melt interactions in the Earth’s crust

ABSTRACT

We discuss the X-ray absorption spectroscopy (XAS) methods elaborated using the high pressure and high-temperature autoclaves installed at FAME and FAME-UHD beamlines. These methods are based on the in situ acquisition of X-ray transmission and fluorescence spectra of hydrothermal fluids and silicate melts and enable the derivation of both solubility and speciation information about metal complexes. The technological assets of our autoclaves are described across a wide range of experimental conditions spanning from different types of hydrothermal fluids, from liquid-like to vapor-like densities having metal concentrations of <1–10,000 ppm, to magmatic fluid-melt systems at 1000°C. Scientific examples are presented to illustrate the use and the advantages of our spectroscopic ‘micro-batch’ reactors. Finally, the integration of our autoclave setups on the FAME-UHD crystal analyzer spectrometer and the benefits of this technique are demonstrated.

KEYWORDS:

• X-ray absorption spectroscopy
• high pressure autoclave
• hydrothermal fluid
• silicate melt
• mineral deposit
• metal speciation
• metal solubility
• in situ studies

Acknowledgements

We acknowledge the European Synchrotron Radiation Facility for provision of synchrotron radiation facilities and we would like to thank the FAME and FAME-UHD staff for assistance. DT thanks François Guyot for fruitful discussions along those years.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The HP/HT autoclave was financially supported by the French ‘grand emprunt’ EquipEx (PlanEx, ANR-11-EQPX-36). The FAME-UHD project is financially supported by the French ‘grand emprunt’ EquipEx (MAGNIFIX, ANR-21-ESRE-0011), the French ‘Programmes et équipements prioritaires de recherche (DIADEM), the CEA-CNRS CRG consortium and the INSU CNRS institute.