Toward integrated geodynamic-petrological modelling: coupling ASPECT with thermodynamic calculations

The concentration of critical minerals and metals occurs within 200 km of the transition between thick and thin lithosphere(Hoggard et al., 2020). Understanding the mechanisms behind this distribution requires characterizing a variety of deep Earth processes of different scales and nature. Among these processes, mantle melting is a critical initial step, controlling compositions of early melts and to the stability of cratonic lithosphere. These melting processes are governed by complex phase equilibria which determines proportions and compositions of mineral assemblages, depending on pressure, temperature and bulk composition. 

 We investigate computational strategies for coupling mantle convection codes such as ASPECT with thermodynamic equilibrium calculations tools like MAGEMin. While a direct coupling would provide accurate phase equilibria predictions, it comes at a significant computational cost for large-scale geodynamic models. Our research explores developing surrogate models using machine learning and neural network techniques to approximate these thermodynamic calculations more efficiently. 

We present our preliminary research involving methodological approaches and discuss the computational trade-offs involved in different coupling strategies. A simplified geodynamic model demonstrates potential workflows for this approach. This research is a step towards a more integrated computational framework for a thermo-chemical geodynamic model, which will have important implications for modelling critical mineral formation in complex geodynamic settings. 

References:

• Hoggard, Mark J., Karol Czarnota, Fred D. Richards, David L. Huston, A. Lynton Jaques, and Sia Ghelichkhan. “Global Distribution of Sediment-Hosted Metals Controlled by Craton Edge Stability.” Nature Geoscience 13, no. 7 (July 2020):504–10.https://doi.org/10.1038/s41561-020-0593-2