Thermodynamics Of Solid Solution Phases And Geothermobarometry

Question 1

What is Geothermobarometry?

Answer 1

Calculation of equilibrium temps and pressures from the measured distribution of elements between coexisting mineral phases

Question 2

When there is mixing in a solid solution series, what happens to GFE as Entropy (S) changes?

Answer 2

As S increases, GFE decreases

Question 3

How can the GFE of a solid solution be determined graphically?

Answer 3

If a graph of chem potential (ų) and composition (X) is plotted with a non-ideal mixture curve on the graph, a line can be drawn tangent to it to find GFE

Question 4

What is activity (a)?

Answer 4

Describes the difference in the chemical potential of a component and the chem potential of the PURE phase of the component

Question 5

What happens when the composition of a phase varies (ex: solid solution)?

Answer 5

The free energy of a phase (change in free energy = chem potential) varies as well

Question 6

In the exchange of Fe-Mg between garnet and biotite, what is the end results of the garnet and biotite?

Answer 6

Garnet exchanges Fe and becomes Mg-garnet and biotite exchanges Mg and becomes Fe-biotite

Question 7

In the exchange between garnet and biotite, using the clapyron equation,what does the slope result look like and why?

Answer 7

The exchange relation has a delta V that is really small, therefore using the clapyron equation the slope will be steep on the P/T diagram