What is amphibolite facies in geology?
amphibolite facies, one of the major divisions of the mineral-facies classification of metamorphic rocks, the rocks of which formed under conditions of moderate to high temperatures (500° C, or about 950° F, maximum) and pressures. Water is usually lost from the parent rock as these changes take place.
What is the concept of metamorphic facies?
In current usage, a metamorphic facies is a set of metamorphic mineral assemblages, repeatedly associated in space and time, such that there is a constant and therefore predictable relation between mineral composition and chemical composition. The facies concept is more or less observation-based.
What are the different types of metamorphic facies?
Contents
- 4.1 Zeolite facies.
- 4.2 Prehnite-pumpellyite facies.
- 4.3 Greenschist facies.
- 4.4 Epidote-amphibolite facies.
- 4.5 Amphibolite facies.
- 4.6 Granulite facies.
- 4.7 Ultra-high-temperature facies.
- 4.8 Blueschist facies.
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.
What is the difference between amphibole and amphibolite?
is that amphibolite is (geology) any of a class of metamorphic rock composed mainly of amphibole with some quartz etc while amphibole is (geology) a large group of structurally similar hydrated double silicate minerals, containing various combinations of sodium, calcium, magnesium, iron, and aluminium/aluminum.
How do you identify amphibolite?
Long prismatic, acicular, or fibrous crystal habit, Mohs hardness between 5 and 6, and two directions of cleavage intersecting at approximately 56° and 124° generally suffice to identify amphiboles in hand specimens. The specific gravity values of amphiboles range from about 2.9 to 3.6.
How the staurolite is formed during amphibolite facies?
Staurolite is formed by regional metamorphism of rocks, such as mica schists, slates, and gneisses, and generally associated with other minerals like kyanite, garnet, and tourmaline.
What is the difference between Blueschist and greenschist facies?
As nouns the difference between blueschist and greenschist is that blueschist is (geology) a metamorphic rock containing glaucophane while greenschist is a metamorphic rock formed at low temperature and pressure, often with an abundance of green minerals such as chlorite, serpentine, and epidote.
What is amphibolite rock?
amphibolite, a rock composed largely or dominantly of minerals of the amphibole group. The term has been applied to rocks of either igneous or metamorphic origin. In igneous rocks, the term hornblendite is more common and restrictive; hornblende is the most common amphibole and is typical of such rocks.
What is amphibolite rock used for?
Amphibolite is a common dimension stone used in construction, paving, facing of buildings, especially because of its attractive textures, dark color, hardness and polishability and its ready availability.
What texture is amphibolite?
The rocks may originate from pelitic sediments, with amphibole (hornblende), plagioclase, and typically include green pyroxene. The amphibolites are characterized by nematoblastic or granoblastic texture.
How the zeolite facies rocks are formed?
Zeolite facies describes the mineral assemblage resulting from the pressure and temperature conditions of low-grade metamorphism. Zeolite facies is most often experienced by pelitic sediments; rocks rich in aluminium, silica, potassium and sodium, but generally low in iron, magnesium and calcium.
What is the amphibolite facies?
Amphibolite facies. Amphibolite facies, one of the major divisions of the mineral-facies classification of metamorphic rocks, the rocks of which formed under conditions of moderate to high temperatures (500° C, or about 950° F, maximum) and pressures. Less intense temperatures and pressures form rocks of the epidote-amphibolite facies,…
Is amphibolite a metamorphic rock?
Amphibolite is a common rock of the metamorphic facies with the same name. However, not all amphibolites were formed within the pressure-temperature limits of the amphibolite facies and by no means are all rocks of this metamorphic facies amphibolites.
How are amphibolite facies formed in orogenic belts?
Water is usually lost from the parent rockas these changes take place. Amphibolite facies rocks are widely distributed in orogenic belts; they are interpreted as having formed in the deeper parts of these folded mountain belts. This article was most recently revised and updated by John P. Rafferty, Editor.
What is the composition of amphibolite?
It is made of amphiboles (usually hornblende) and plagioclase. Most samples have a relatively simple composition: hornblende + plagioclase. Garnet (almandine), pyroxene, biotite, titanite, magnetite, epidote, chlorite, and quartz are also frequent constituents. Main minerals in amphibolite are plagioclase (white) and hornblende.