eclogite facies

The eclogite facies represents a specific set of pressure-temperature conditions under which rocks transform. Initially recognized in basaltic rocks, these conditions convert them into dense, red and green rocks composed mainly of garnet and omphacite, minerals rich in high-pressure components like pyrope and jadeite.1

While basaltic compositions were the first recognized, other rock types can also undergo metamorphism within the eclogite facies, resulting in various mineral assemblages. These conditions are typically achieved through deep burial, around 35 km, and temperatures ranging from 400 to 1,000 °C. Eclogites are dense rocks and are thought to be representative of parts of the Earth's upper mantle, often found as inclusions in volcanic rocks or kimberlites. Their formation is linked to subduction zones, where oceanic crust is forced beneath another plate, experiencing the high pressures characteristic of this facies.123