Aqueous fluids play an important role in most geological processes of the Earth's crust and upper mantle. The speciation of dissolved components in the fluid is a key parameter for the understanding of both thermodynamics and kinetics of fluid-rock interactions. To model geological environments of the Earth's interior, the molecular structure of the fluid has to be studied in situ up to very high pressures and temperatures. Ab initio molecular dynamics simulations have become a powerful tool to complement experimental approaches in this respect. Here, we will present results of own recent work on fluid speciation that combines ab initio molecular dynamics with in situ Raman and x-ray absorption spectroscopy. Using a new efficient method, we are able to predict equilibrium isotope fractionation factors between aqueous fluids and minerals in good agreement with experiment, which will be demonstrated for B and Li isotopes.

From fluid speciation to the thermodynamics of fluid-rock interactions: Insights from DFT calculations

243rd National Meeting (2012)

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