Clinopyroxene thermobarometry
Many different minerals can be used for geothermobarometry, but clinopyroxene is especially useful because it's a common phenocryst in igneous rocks and easy to identify, and the crystallization of jadeite, a type of clinopyroxene, implies a growth in molar volume, making it a good indicator of pressure.
[1] The data given by this technique is used for understanding magmatic crystallization, prograde and retrograde metamorphism, and ore deposit formation.
[3] Thermobarometry uses equilibrium constants to calculate information about the environmental conditions present during the rocks' formation.
[2] While each rock is forming, it reacts with the surrounding elements until it cools down enough to become inert.
[2] Individual reactions of specific minerals can be used to calculate either the temperature or pressure.
Therefore, two different reactions are needed to calculate both the temperature and pressure of the magma for a single rock.
Some reactions are better for pressure and others are better for temperature, based on thermodynamics and Le Chatelier's Principle.
This technique requires each reaction to be calibrated, which is done through experimentation and data analysis.
Experimentation involves simulating the temperatures and pressures at which these rocks form and observing how the reaction proceeds at those conditions, while data analysis relies on amassing a large database of rock samples with pressure and temperature information.
Based on the temperature and pressure conditions, different proportions of these phases will emerge in the final rock.
[2] This is a common method to calculate the temperature because most exchange reactions have a high enthalpy.
Solvus Equilibria reactions occur when two phases dissolve into each other based on the temperature, so it is usually useful for geothermometry.
Instead of mining every kimberlite found, they can be sampled to see if they formed in an environment that would have favored the crystallization of diamonds.
Other applications are largely scientific; pressure and temperature data about magma can be used to propose detailed models of the lithosphere and mantle.
[3] These models enhance understanding of geological and volcanic activity, which may contribute to scientists' ability to predict events such as eruptions or earthquakes.
