T-X Animation

Tony Withers, Earth Sciences, University of Western Ontario


This is an animation of reactions on a T-X diagram. The T-X diagram shows just two of the possible reactions in the CaO-MgO-SiO2-H2O-CO2 system. A similar diagram appears in Chapter 26 of Winter and a more complete one is found in the Metamorphic T-X Phase Diagrams page of this site. The phase diagram was calculated using thermodynamic data from Holland and Powell, assuming ideal mixing of non-ideal gases with fugacites from Pitzer and Sterner 1994.


How this visualization is used in class:

I use this when talking about internal vs external buffering of fluid compositions. The three animations illustrate the possible extent of reactions, starting with different phase proportions. Two of the animations differ only in fluid/rock ratio.


  • Tony Withers, University of Western Ontario

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