What are the facies of regional metamorphism?
The facies associated with regional metamorphism include, at low grade, the zeolite and prehnite-pumpellyite facies. In areas belonging to high-pressure facies series, the rocks are predominantly in the blueschist and eclogite facies.
Which metamorphic facies is associated with burial metamorphism?
The two metamorphic facies of burial metamorphism (Coombs, 1961) are, with decreasing grade following the greenschist facies, (1) prehnite–pumpellyite facies and (2) zeolite facies (see also Pumpellyite –actinolite schist facies).
What are the 4 main types of metamorphism?
Hydro-Thermo-Metamorphism.
- Type # 1. Contact Metamorphism:
- Type # 2. Regional Metamorphism:
- Type # 3. Hydro-Metamorphism:
- Type # 4. Hydro-Thermo-Metamorphism:
What metamorphic facies is Quartzite?
The two most common examples of non-foliated rocks are quartzite and marble. Quartzite is a metamorphic rock from the protolith sandstone. In quartzites, the quartz grains from the original sandstone are enlarged and interlocked by recrystallization.
What is regional Dynamothermal metamorphism?
Most metamorphic rocks are the result of regional metamorphism (also called dynamothermal metamorphism). These rocks were typically exposed to tectonic forces and associated high pressures and temperatures. They are usually foliated and deformed and thought to be remnants of ancient mountain ranges.
What is Dynamothermal metamorphism?
Dynamothermal metamorphism is due to the co-operation of directed pressure and heat. The heat element facilitates recrystallisation; but the stress element not only promotes recrystallisation, but is powerful in deforming the rocks, and producing new structures.
What metamorphic facies is Garnet?
The blueschist metamorphic facies are characterized by the minerals jadeite, glaucophane, epidote, lawsonite, and garnet. They record metamorphism in the cool high-pressure/low-temperature thermal gradients at less than 7°C/km in subduction zones in the last 1 billion years.
How are amphibolite facies formed?
Amphibolite frequently forms by metamorphism of mafic igneous rocks, such as basalt. However, because metamorphism creates minerals entirely based upon the chemistry of the protolith, certain ‘dirty marls’ and volcanic sediments may also metamorphose to an amphibolite assemblage.
What is prominent during Dynamothermal metamorphism?
Most metamorphic rocks are the result of regional metamorphism (also called dynamothermal metamorphism). These rocks were typically exposed to tectonic forces and associated high pressures and temperatures. They are usually foliated and deformed and thought to be remnants of ancient mountain ranges. Metamorphic grades.
Which of the factor plays important role in Dynamothermal metamorphism?
Dynamothermal metamorphism: where both pressure and temperature play a major role in effecting recrystallization and mineral growth. Several types of regional metamorphism fall into this category.
What is the metamorphic facies of gneiss?
Gneisses are characteristic of areas of regional metamorphism that reaches the middle amphibolite to granulite metamorphic facies. In other words, the rock was metamorphosed at a temperature in excess of 600 °C (1,112 °F) at pressures between about 2 to 24 kbar.
What minerals are in the greenschist facies?
The more common minerals found in such rocks include quartz, orthoclase, muscovite, chlorite, serpentine, talc, and epidote; carbonate minerals and amphibole (actinolite) may also be present.
What minerals are in the amphibolite facies?
Minerals typical of the rocks of the epidote-amphibolite facies include biotite, almandite garnet, plagioclase, epidote, and amphibole. Chlorite, muscovite, staurolite, and chloritoid may also occur.
What type of metamorphism is amphibolite?
Amphibolite is a rock of convergent plate boundaries where heat and pressure cause regional metamorphism. It can be produced through the metamorphism of mafic igneous rocks such as basalt and gabbro, or from the metamorphism of clay-rich sedimentary rocks such as marl or graywacke.
Which metamorphic facies is slate?
Slate is a low-grade metamorphic rock generally formed by the metamorphosis of mudstone, shale, or sometimes volcanic ash, under relatively low pressure and temperature conditions (prehnite-pumpellyite facies). With increasing metamorphic grade increases in muscovite grain-size transforms slate into phyllite.
What is the metamorphic facies of marble?
Marble is a metamorphic rock that forms when limestone is subjected to the heat and pressure of metamorphism. It is composed primarily of the mineral calcite (CaCO3) and usually contains other minerals, such as clay minerals, micas, quartz, pyrite, iron oxides, and graphite.
Where are greenschist facies found?
Greenschist facies prevail in the middle levels of oceanic crust and upper levels of orogenic belts. Many supracrustal rocks in Archean terranes are metamorphosed at greenschist facies, hence the name “greenstone belts.”
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.
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.
What’s the difference between shale and slate?
If the clay is deposited in layers and has a tendency to split along the bedding planes, it is shale. If it is tilted up at a new angle and was compressed so that it spread out and produced cleavage planes at right angles to the direction of pressure, it is slate.
Is slate a regional or contact?
| Summary Chart of Common Metamorphic Rocks | ||
|---|---|---|
| Original Rocks | Metamorphic Equivalent | Metamorphism |
| sandstone | quartzite | regional & contact |
| shale | slate >> phyllite >> schist >> gneiss | regional |
| limestone | marble | contact |
How many metamorphic facies are there?
There are seven widely recognized metamorphic facies, ranging from the zeolite facies at low P and T to eclogite at very high P and T. Geologists determine a facies in the lab after examining many specimens under the microscope and doing bulk chemistry analyses.
Where is greenschist formed?
Greenschists are metamorphic rocks that formed under the lowest temperatures and pressures usually produced by regional metamorphism, typically 300–450 °C (570–840 °F) and 2–10 kilobars (29,000–145,000 psi).
What is eclogite facies in geology?
Eclogites or eclogite facie of rocks forms at extremely high pressure and very high temperature (Fig. 7.9) from mafic magmatites rocks of gabbro and basalt. The optimum pressures required for the formation of eclogites is certainly much greater than the typical pressures of Earth’s crust.
How do you remember metamorphic facies?
Metamorphic Grades
I remember the order of the index minerals with the mnemonic “CBGSKS”, which I read as “See Bigs kiss”. I recall that gneiss is the highest grade because it is…”nice”. Above gneiss, when the rock actually starts to melt, it is called a migmatite.