metamorphic grade

geology

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June 30, 2026

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Metamorphic grade refers to the relative temperature and pressure conditions under which a metamorphic rock formed. It's a way to classify the intensity of metamorphism a rock has undergone. Higher grades indicate higher temperatures and pressures, leading to more significant changes in the rock's mineralogy and texture.12

Metamorphic rocks are classified into different "facies" based on their mineral assemblages, which are indicative of specific pressure-temperature conditions. For example, the greenschist facies represents lower-grade metamorphism, while the amphibolite and granulite facies represent higher grades. The specific minerals present in a metamorphic rock, such as garnet or sillimanite, can help geologists determine its metamorphic grade.345

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metamorphic rock
Regional metamorphism
(Metamorphic grades refer to the degree and intensity of the metamorphism: they are determined by the pressure and temperatures to which the rock has been subjected.) Such areas are generally referred to as metamorphic core complexes. Metamorphism in these complexes may or may not be…
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(Metamorphic grades refer to the degree and intensity of the metamorphism: they are determined by the pressure and temperatures to which the rock has been subjected.) Such areas are generally referred to as metamorphic core complexes. Metamorphism in these complexes may or may not be…
Read More