My thesis looks at rocks from the aureole of the Bushveld Layered Mafic Series to work out metamorphic reaction kinetics. The methods are simple and involve Crystal Size Distribution (CSD) analysis. Tracings are made either from projections of thin sections or the rock faces themselves of the porphyroblasts. The snap below was taken at an andalusite quarry of andalusite (chiastolite) porphyroblasts which are nice and easy to get accurate tracings of. Chiastolites can be about half an inch wide and 4 inches wide - the piece of paper in the drawing is A5 sized.
Image analysis is then carried out which allows a CSD to be generated by means of a histogram. The characteristics of the histogram can be summarised by a single number which is then compared with forward models of crystal nucleation and growth at the various rates of heating experienced at different parts of the aureole. Small crystals are produced when heating is rapid - it is best viewed from the diagram below.
One related paper has already been published, dealing mainly with calculating overstepping using petrological observations:
Waters, D. J. & Lovegrove, D. P., 2002. Assessing the extent of disequilibrium and overstepping of prograde metamorphic reactions in metapelites from the Bushveld Complex aureole, South Africa. Journal of Metamorphic Geology, 20, 135-149.
Another one dealing with the results is in the pipeline. Here is the title and abstract: