Geothermobarometry. How do we know P and T?. Need min. at equilibrium. Good barometer rxn vs. good thermometer rxn Which has large D V and which has large D S?. D. dP. S. =. D. dT. V. Geothermobarometry.
Estimate P and T of equilibrium in natural samples
Garnet-biotite exchange reaction
K: (Mg/Fe)GarnetGood thermometer