In-situ determination of the speciation of Nd and Yb in high P-T fluids: Towards an improved modeling of the formation of REE ore deposits

Over the last 20 years, rare earth elements (REE: La to Lu, +Sc, Y) have become of critical importance to the development of new technologies and transition to carbon-free energy. A detailed understanding of REE aqueous chemistry is key to modeling the processes that enable their concentration to economic level in the Earth’s crust. Yet, current thermodynamic models only really on a scarce set of experimental data, mostly collected at T< 500C and P < 1kbar to describe REE aqueous transport and concentration. To tackle this issue, we propose to constrain the speciation of Nd and Yb in high P-T fluids conducting in-situ XAS analysis in RH-DAC. The obtained results will complete an experimental dataset developed for almost 10 years by the co-proposers and enable the development of more accurate depositional models for the REE.