The Al2SiO5 polymorphs / Полиморфизм Al2SiO5

The Al2SiOs polymorphs continue to be of paramount importance in metamorphic petrology. Their usefulness stems from their abundance in metapelites, the fact that some isograd reactions in metapelites correspond to polymorphic transformations involving the aluminum silicates, and the simple pressure-temperature (P- T) phase equilibrium relations of the Al2SiOs system. Although numerous other thermo barometers have been developed and utilized (especially within the last decade), petrologists still consider the AI2SiOs polymorphs for primary thermo barometry of metamorphic rocks. In fact, the Al2SiOs phase equilibria are used to calibrate other geothermometers and geobarometers. The following review highlights some landmark papers exemplifying the petrologic significance of the Al2SiOs polymorphs. <...>