140 likes | 953 Views
Geothermobarametry. Gibbs-Duhem equation describes how T and P changes affect free energy (as chemical potential). Reaction with big D S R change a good barometer, reaction with a big D V R change a good thermometer…. Clausius-Clapeyron. Thermobarometry reactions.
E N D
Geothermobarametry • Gibbs-Duhem equation describes how T and P changes affect free energy (as chemical potential) Reaction with big DSR change a good barometer, reaction with a big DVR change a good thermometer…. Clausius-Clapeyron
Thermobarometry reactions • Exchange Reactions - For solid solution series (Fe-Mg in olivine or pyroxene for example) T and P control the equilibrium distribution • Solvus thermometry – For minerals that exsolve, T at which 1 phase splits to 2 components dtermined by chemistry of the 2 components • Trace element substitution into a certain mineral is T/P dependent (KD changes with T and P!) • Isotope distributions in minerals are also T/P dependent
Garnet-Biotite Geothermometer From Selverstone,: http://serc.carleton.edu/files/NAGTWorkshops/petrology/teaching_examples/Selverstone_thermobarometry.pdf