|
Our transcription: As basalt is metamorphosed to different combinations of temperature and pressure, its mineral composition changes as the rock re-equilibrates to its new condition. These zones on the chart are called "metamorphic facies," and each facies is defined by the formation during metamorphism of a particular mineral or mineral assemblage. For example, this is a metamorphosed basalt containing the mineral "amphibole." Amphibole forms at a temperature between 450 and 700 degrees centigrade and at a pressure corresponding to a depth of at least six kilometers. So this metamorphosed basalt would plot here on a chart in the amphibolite facies.
|
