Most regional metamorphic rocks are formed in conditions within this range of geothermal gradients, passing through the greenschist facies to the amphibolites
It's eclogite facies.
blue schist facies
A metamorphic grade takes into account only the change in temperature while a metamorphic facies is more specific by showing the change in temperature in relation to the change in pressure and depth. There are three grades: low (250°C-400°C), intermediate (400°C-600°C) and high (above 600°C). Although there are many facies, the major ones are zeolite, hornfels, greenschist, amphibolite, blueschist, eclogite, and granulite. This allows for geologist to easily locate where a metamorphic rock was formed.
metamorphic facies. This indicates that these rocks formed under similar pressure and temperature conditions despite coming from different locations.
Depending on the pressure and temperature conditions under which a rock undergoes metamorphism, differing groups of minerals tend to form. These differing groups formed under differing conditions are known as metamorphic facies. For more information, please see the related link.
sedimentary facies
Facies changes in sedimentary rocks refer to transitions in the characteristics of sedimentary deposits, such as grain size, composition, and sedimentary structures, over time and space. These changes can indicate shifts in environments of deposition, such as from a river to a delta or from shallow to deep marine settings. By studying facies changes, geologists can reconstruct the environmental conditions that existed in the past.
Zeolite and prehnite-pumpellyite facies are characteristic of burial metamorphism. These facies typically occur at low to medium pressures and temperatures, representing the early stages of metamorphism when sediments are first buried and compacted.
The blueschist facies is a metamorphic realm of low-temperature, high-pressure conditions typically found in subduction zones. It is characterized by the presence of minerals such as glaucophane and lawsonite, and indicates that rocks have undergone metamorphism at depths of 15-30 kilometers. This facies is important for understanding the processes of subduction and the formation of mountain belts.
Hans-Martin Albat has written: 'The Proterozoic granulite facies terrane around Kliprand, Namaqualand Metamorphic Complex' -- subject(s): Facies (Geology), Geology, Granulite, Stratigraphic Geology
Philip R. Royce has written: 'Stratigraphy, provinance and facies analysis of the Albian-Turonian Virginian Ridge Formation and Winthrop Sandstone, Methow Basin, northeastern Cascades, Washington' -- subject(s): Facies (Geology), Geology, Stratigraphic, Rocks, Sedimentary, Sedimentary Rocks, Sedimentation and deposition, Sediments (Geology), Stratigraphic Geology
In geology, a facies is a body of rock with specified characteristics.