What are metamorphic facies series?
What are metamorphic facies series?
• A metamorphic facies series is a sequence of facies that. occurs across a metamorphic terrane due to differences in pressure and temperature (P/T) conditions. • Variations in P/T conditions are related to both space and. time.
How do you identify metamorphic facies?
Metamorphic facies is not obvious in a given field specimen. To sum up, a metamorphic facies is the set of minerals found in a rock of a given composition. That mineral suite is taken as a sign of the pressure and temperature that made it. Here are the typical minerals in rocks that are derived from sediments.
Who proposed metamorphic facies?
Eskola
The classical metamorphic facies diagram, as proposed by Eskola (1920) and later refined in many textbooks (e.g., Bucher and Frey, 2002; Spear, 1993), provides a framework to place metamorphic rocks of crustal composition into a region of pressure–temperature (P–T) space, based on mineral assemblages (Figure 1).
How does metamorphic grade differ from facies?
Metamorphic grade is usually assessed on the basis of the mineral assemblage making up the metamorphic rock, as well as its foliation and other textural clues (such as grain size). Facies is a more precise term used for a restricted range of temperatures and pressures defined by the presence of key minerals.
How many metamorphic facies are there?
Miyashiro described the three facies associations given above as high-pressure, medium-pressure, and low-pressure facies series, respectively, and correlated the development of these characteristic series with the shape of the geotherm (a line or surface connecting points of equal temperature either on or within Earth) …
Is greenschist a metamorphic facies?
greenschist facies, one of the major divisions of the mineral facies classification of metamorphic rocks, the rocks of which formed under the lowest temperature and pressure conditions usually produced by regional metamorphism.
Which facies is lowest grade of metamorphism?
The zeolite facies is the metamorphic facies with the lowest metamorphic grade. At lower temperature and pressure processes in the rock are called diagenesis.
What type of rock is peridotite?
Peridotite
| Type | Igneous Rock |
|---|---|
| Texture | Phaneritic (Coarse-grained) |
| Origin | Intrusive/Plutonic |
| Chemical Composition | Ultramafic |
| Color | Medium Green |
Which metamorphic facies is characteristic of contact metamorphism?
The contact metamorphic rocks of the aureole zone often lack any obvious schistosity or foliation. The facies associated with contact metamorphism include the sanidinite, pyroxenite-hornfels, hornblende-hornfels, and albite-epidote-hornfels facies.
How are facies related to the formation of metamorphic rocks?
In other words, a given metamorphic facies groups together metamorphic rocks that form under the same pressure and temperature conditions, but which have different protoliths. Figure 10.35 shows the different metamorphic facies as patches of different colours.
How are metamorphic facies related to the protolith?
While these rocks will be exposed to the same range of pressure and temperatures conditions within that setting, the metamorphic rock that results will depend on the protolith. A convenient way to indicate the range of possible metamorphic rocks in a particular setting is to group those possibilities into metamorphic facies.
What are the characteristics of a facies model?
Gressly intended facies to represent a reasonably objective description of sedimentary beds, including characteristics like texture, colour, sedimentary structures, and fossils.
Can a facies model be cast in stone?
Facies models are not cast-in-stone; if a model requires too much tweaking to provide meaningful comparisons, then it needs modification or replacement by a new model. Those who use facies models also carry the burden of avoiding pigeonholing of depositional environments.