My research group has been working on developing new techniques for the interpretation of metamorphic petrogenesis and especially mineral reactions and chemical zonation. The mineral garnet has proved to be an exceptionally good recorder of reaction histories. Some accessory minerals also record a rock's history. Monazite is especially useful because it can also be dated, to provide not only a temperature but a time of formation. We have applied these techniques to areas in the Alps, New England, southern Chile, British Columbia, the Mojave desert, the Adirondacks of New York, the Limpopo belt of South Africa and the Caledonides of Norway.
Warm colors are high concentration, cool colors are low concentration.
The reaction history and zoning observed in minerals confirms a counterclockwise P-T path and nearly isobaric cooling for these rocks.