Direct coupling of petrological and thermo-kinematic modelling: application to magmatic chambers

Understanding how magmatic systems work is of interest to a wide range of Earth Scientists. One of the key components when studying magmatic systems is the ability to predict stable mineral assemblage. These predictions allow retrieving critical information such as mineral stability, fraction and composition of melt.

However, the dynamic evolution of magmatic chambers, including the cycling between magmatic recharge and extraction in and out of the reservoir, imply that compositions of crystals and melts are constantly evolving. Hence, the use of phase equilibrium parameterization or look-up-tables of fixed bulk-rock composition is inappropriate to predict the dynamic chemical evolution of magmatic systems, and we instead need methods that can take the evolving chemistry into account.

Here, we present an updated version of our in-house Gibbs energy minimization package, MAGEMin [1,2]. MAGEMin is ideally suited so simulate the chemical evolution of magmatic systems by incorporating a range of recently developed thermodynamic melting models suitable to simulate both melting of magmatic arcs and of pelitic crustal rocks. Through its Julia wrapper, MAGEMin_C, it is particularly easy to perform (parallel) pointwise computations, and couple it with other thermal or thermomechanical codes.

We have made several additions to MAGEMin which include a) adding more thermodynamic databases, b) developing a new web-based graphical user interface, MAGEMin_app, which simplifies creating publishable phase diagrams and c) coupling MAGEMin with dynamic codes.

The ability to couple MAGEMin with other codes is demonstrated by linking it with the MagmaThermoKinematics.jl Julia package [4,5] that simulates the thermal evolution of magmatic systems following the intrusion of dikes and sills, in 2D, 2D axisymmetric and 3D geometries. For this to be efficient, we develop a new system in which we dynamically create a database of pre-computed points as a function of pressure, temperature and chemistry that is updated on the fly. This allows simulating the evolving chemistry of a crustal-scale mush system.

 

[1] Riel, N., Kaus, B.J.P., Green, E.C.R., Berlie, N., 2022. MAGEMin, an Efficient Gibbs Energy Minimizer: Application to Igneous Systems. Geochem Geophys Geosyst 23. https://doi.org/10.1029/2022GC010427

[2] https://github.com/ComputationalThermodynamics/MAGEMin

[3] https://github.com/ComputationalThermodynamics/MAGEMin_C.jl

[4] Schmitt, A.K., Sliwinski, J., Caricchi, L., Bachmann, O., Riel, N., Kaus, B.J.P., de Léon, A.C., Cornet, J., Friedrichs, B., Lovera, O., Sheldrake, T., Weber, G., n.d. Zircon age spectra to quantify magma evolution. Geosphere 19. https://doi.org/10.1130/GES02563.1

[5] https://github.com/boriskaus/MagmaThermoKinematics.jl