Thermodynamics in petrogenesis 1300-OTPGP-GEP

The course allows the student to get acquinted with the issues of the equilibrium thermodynamics in chemical approach as the closest in terms of describing the geological processes. Both the fundamentals and more advanced problems are discussed in geological context; as much as possible, assignmens and exercices are related to mineralogy and igneous or metamorphic petrology. First part introduces the concept of the system (open, closed, isolated, etc.), component and phase, equilibrium and reversible process, internal energy, work (including maximum work), heat and temperature, enthalpy, enthropy, Gibbs free energy, chemical potential, criteria for equilibrium and spontaneous reactions. First part is concluded with simple phase diagrams that show the state of equilibrium and predictable chemical reactions (e.g. diagrams for kyanite-sillimanite-andalusite, calcite-aragonite, equilibria and reactions between minerals in the MgO–CaO–H2O system etc.)
The second part of the course, due to widespread presence of solutions in natural systems (e.g. volcanic gases, oceanic water, magma, minerals), shows them in thermodynamic approach. Starting from fundamental laws (Henry’s and Raoult’s laws), thermodynamic properties and functions, standard states and activities are discussed for ideal and real solutions. Subsequently the concept of chemical-mineral equilibrium is introduced with special reference to the equilibrium constant of chemical reaction and its bearing on study of igneous and metamorphic rocks.
The third and final part of the course presents the binary and ternary phase diagrams and their importance in deciphering the pathways of mafic and felsic magma crystallization.
Each element of the tripartite theoretical issues is dealt with through worked examples and problems which are completed either graphically or algebraically. The exercises are based as much as possible on geological and natural systems cases. The proposed course shows thermodynamic approach as an effective tool for solving petrological problems and reconstruction of conditions of mineral stabilities and reactions.