What type of metamorphic rock is greenschist?
foliated metamorphic rock
Greenschist is a fine- to medium-grained foliated metamorphic rock dominated by chlorite, actinolite and epidote, with or without albite, quartz and calcite.
What metamorphic grade is greenschist?
Definition. Greenschist facies is one of the major divisions of the mineral facies classification of metamorphic rocks. Greenschist facies refers to the low to medium metamorphic facies corresponding to temperatures of about 300–500°C and pressures of 3–20 kbar (crustal depths of 8–50 km).
What is the parent rock of greenschist?
Even though greenschist does not imply a specific parent rock, for our purposes we will assign a shale parent as a way of distinguishing it from a greenstone, which has a mafic parent.
What minerals are in greenschist?
Mineralogy of GreenschistHide
| Actinolite | ◻Ca2(Mg4.5-2.5Fe0.5-2.5)Si8O22OH2 |
|---|---|
| Chlorite | A name commonly used for undifferentiated members of the chlorite group. |
| Epidote | {Ca2}{Al2Fe3+}(Si2O7)(SiO4)O(OH) |
What is greenschist facies in geology?
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.
What is the parent rock of greenstone and greenschist quizlet?
For example, greenschist (shale parent) and greenstone (mafic igneous parent).
Where do you find greenschist?
These ancient rocks are noted as host rocks for a variety of ore deposits in Australia, Namibia and Canada. Greenschist-like rocks can also be formed under blueschist facies conditions if the original rock (protolith) contains enough magnesium.
Which is a member of amphibole group is characteristic of greenschist?
Actinolite is an Al-poor amphibole; it contains mainly tremolite. Actinolite is green in hand specimen and colourless to pale green under the microscope. Plagioclase is pure albite and contains no Ca. The two minerals are the major constituents of greenschists.
Which of the mineral assemblages are characteristic of a greenschist quizlet?
Greenschist contains Chlorite and Biotite Zones. Transition States contain Biotite and Garnet Zones.
What is meant by Metasomatism?
Metasomatism refers to the process whereby a preexisting igneous, sedimentary, or metamorphic rock undergoes compositional and mineralogical transformations associated with chemical reactions triggered by the reaction of fluids (so-called metasomatic agents), which invade the protolith.
Is zeolite metamorphic?
zeolite facies, one of the major divisions of the mineral facies classification of metamorphic rocks, the rocks of which formed at the lowest temperatures and pressures associated with regional metamorphism.
Is zeolite a rock or mineral?
Zeolites occur in a wide variety of sedimentary rocks. They are postdepositional minerals and form from varied types of materials including volcanic glass, feldspar, feldspathoids, smectite, and kaolinite.
What is sub greenschist facies?
Which of the mineral assemblages are characteristic of a greenschist?
Greenschist contains Chlorite and Biotite Zones. Transition States contain Biotite and Garnet Zones. Amphibolite contains Late Garnet, Staurolite/Kyanite, Sillimanite-Muscovite Zones.
When magma intrudes into a host rock the immediately adjacent rock is metamorphosed What is this process called?
Contact metamorphism occurs adjacent to a pluton when a body of magma intrudes relatively cool country rock. Andalusite, kyanite, and sillimanite are among the best known index minerals that provide information about the temperature and pressure of metamorphism.
What is metasomatism in metamorphic rocks?
Where does metasomatism occur?
Metasomatism takes place in some rocks adjacent to igneous intrusions (see Contact (thermal) metamorphism; Skarn). It may also affect extensive areas (regional metasomatism), with the introduction of fluids possibly related to partial fusion at depth.
What is a zeolite mineral?
zeolite, any member of a family of hydrated aluminosilicate minerals that contain alkali and alkaline-earth metals. The zeolites are noted for their lability toward ion-exchange and reversible dehydration.
Why are metamorphic rocks called greenschist?
metamorphic rock: Greenschist facies. The greenschist facies was once considered the first major facies of metamorphism proper. The name comes from the abundance of the green mineral chlorite in such rocks. Because chlorite and muscovite are ubiquitous and because both exhibit a platy crystal habit, these rocks….
Where are greenschist rocks found?
The greenstone belts of the various archean cratons are commonly altered to the greenschist facies. These ancient rocks are noted as host rocks for a variety of ore deposits in Australia, Namibia and Canada . Greenschist rocks have been used to make axes across Europe.
What is greenschist facies in metamorphism?
Greenschist facies. Greenschist facies is determined by the particular temperature and pressure conditions required to metamorphose basalt to form the typical greenschist facies minerals chlorite, actinolite, and albite. Greenschist facies results from low temperature, moderate pressure metamorphism.
What type of metamorphism is schist?
Schist. It is formed by dynamic metamorphism at high temperatures and high pressures that aligns the grains of mica, hornblende, and other flat or elongated minerals into thin layers, or foliation. At least 50 percent of the mineral grains in schist are aligned this way (less than 50 percent makes it gneiss ).