Terms used to describe the sequence of pressure(P) – temperature(T) conditions that occurred in a given rock body over a period of time (t) of a particular metamorphic event. Also called P–T–t paths.
Definitions are largely derived from:
a) England, PC and Richardson, SW 1977, The influence of erosion upon the mineral facies of rocks from different metamorphic environments: Journal of the Geological Society, v. 134, p. 201–213, doi:10.1144/gsjgs.134.2.0201)
b) England, PC and Thompson, AB 1984, Pressure-temperature-time paths of regional metamorphism I. Heat transfer during the evolution of thickened continental crust: Journal of Petrology, v. 25, no. 4, p. 894–928)
c) Harley, 1989 (Harley, SL 1989, The origins of granulites: a metamorphic perspective: Geological Magazine, v. 126, no. 3, p. 215–247, doi:10.1017/S0016756800022330)
d) https://en.wikipedia.org/wiki/Pressure-temperature-time_path.