MCS and MELTS: What is the relationship?

In its root level, the Magma Chamber Simulator (MCS) is the marriage between a computational thermodynamic engine and an executive brain. The thermodynamic engine is one of the MELTS codes (v1.2.x, 1.1.x, 1.0.x, pMELTS) for performing phase equilibria calculations based on user- supplied parameters. The executive brain or command and control element of the MCS is called IGOR (pronounced EYE-GOR thanks to Mel Brooks). IGOR is responsible for implementing the particular RnAFC scenario specified by the user in the input file (MES_filename) by (1) sending instructions to the phase equilibria computational engine, (2) performing additional internal calculations based on values returned to IGOR from MELTS and (3) making conditional sequential executive decisions required to carry out the user-defined RnAFC petrological scenario based on (2). IGOR also handles the setup for graphical output and generates text output files to facilitate the interpretation of the MCS simulation. IGOR is smart enough to sometimes indicate why a run was not able to be completed. It is best not to (ever) humiliate IGOR.

More on MELTS engine

The engine within the MCS is one of four versions of the MELTS software created and developed by Mark Ghiorso and his collaborators. The MELTS website with information about MELTS is A century after the start of the pioneering work of N.L. Bowen, MELTS stands as the ‘go-to’ thermodynamic algorithm for computing multiphase-multicomponent phase equilibria in high-temperature molten or partially-molten silicate-oxide volatile-bearing systems at crustal and upper mantle conditions of temperature, pressure and redox potential subject to specific thermodynamic constraints. Literature references for MELTS include:

Ghiorso, Mark S., and Sack, Richard O. (1995) Chemical Mass Transfer in Magmatic Processes. IV. A Revised and Internally Consistent Thermodynamic Model for the Interpolation and Extrapolation of Liquid-Solid Equilibria in Magmatic Systems at Elevated Temperatures and Pressures. Contributions to Mineralogy and Petrology, 119, 197-212

Asimow PD, Ghiorso MS (1998) Algorithmic Modifications Extending MELTS to Calculate Subsolidus Phase Relations. American Mineralogist 83, 1127-1131;

Ghiorso, Mark S., Hirschmann, Marc M., Reiners, Peter W., and Kress, Victor C. III (2002) The pMELTS: An revision of MELTS aimed at improving calculation of phase relations and major element partitioning involved in partial melting of the mantle at pressures up to 3 GPa. Geochemistry, Geophysics, Geosystems 3(5), 10.1029/2001GC000217

Gualda G.A.R., Ghiorso M.S., Lemons R.V., Carley T.L. (2012) Rhyolite-MELTS: A modified calibration of MELTS optimized for silica-rich, fluid-bearing magmatic systems. Journal of Petrology, 53, 875-890

Ghiorso M.S., Gualda, G.A.R., (2015) An H2O-CO2 mixed fluid saturation model compatible with rhyolite-MELTS. Contributions to Mineralogy and Petrology 2015, in press