Define granulite facies in geology?
Domanda di: Dr. Matilde De Santis | Ultimo aggiornamento: 29 dicembre 2021Valutazione: 4.7/5 (31 voti)
granulite facies, one of the major divisions of the mineral facies classification of metamorphic rocks, the rocks of which formed under the most intense temperature-pressure conditions usually found in regional metamorphism. At the upper limit of the facies, migmatite formation may occur.
How are granulite facies formed?
Formation. Granulites form at crustal depths, typically during regional metamorphism at high thermal gradients of greater than 30 °C/km. In continental crustal rocks, biotite may break down at high temperatures to form orthopyroxene + potassium feldspar + water, producing a granulite.
What is a metamorphic facies in geology?
A metamorphic facies is a set of mineral assemblages in metamorphic rocks formed under similar pressures and temperatures. ... The boundaries between facies (and corresponding areas on the temperature v. pressure graph) are wide because they are gradational and approximate.
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 type of rock is Granulite?
About GranuliteHide
A high-grade metamorphic rock in which the silicates are dominantly water-free, eg, feldspars, garnet, pyroxene; the presence of feldspar and the absence of primary muscovite are critical, and cordierite may also be present.
GRANULITE FACIES
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What is granitoid rock?
A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. ... The terms granite and granitic rock are often used interchangeably for granitoids; however, granite is just one particular type of granitoid.
What is Charnockite rock?
Charnockite (/ˈtʃɑːrnəkaɪt/) is any orthopyroxene-bearing quartz-feldspar rock formed at high temperature and pressure, commonly found in granulite facies metamorphic regions, sensu stricto as an endmember of the charnockite series.
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 the difference between amphibole and amphibolite?
The metamorphism sometimes flattens and elongates the mineral grains to produce a schistose texture. Amphibolite: Some amphibolites are greenish, as determined by the color of the amphibole minerals.
What is Metabasic rock?
Metabasic rocks form an important constituent of the Chynov and Cesky Krumlov units belonging to the Varied Group (Moldanubian Zone, south Bohemia). The amphibolites are dominated by amphibolite-facies mineral assemblages of mainly tschermakitic amphibole and plagioclase.
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.
What metamorphic facies is Quartzite?
Quartzite is a nonfoliated metamorphic rock composed almost entirely of quartz. It forms when a quartz-rich sandstone is altered by the heat, pressure, and chemical activity of metamorphism.
Is eclogite a metamorphic facies?
The protoliths of eclogites are igneous rocks with a basaltic composition (basalt, diabase, gabbro). ... It is a rock type that gave name to a metamorphic facies. Eclogite facies is characterized by pressures in excess of 1.2 GPa (45 km depth) and temperature exceeding at least 400-500 °C.
What is mafic granulite?
Granulite: Granulite is a high-grade metamorphic rock in which Fe-Mg-silicates are dominantly hydroxyl-free; the presence of feldspar and the absence of primary muscovite are critical, cordierite may also be present. The mineral composition is to be indicated by prefixing the major constituents.
What is Granulite used for?
In addition, Granulite fertilizer can be used on flowers, lawns and turf (golf courses, playing fields and sod). Granulite fertilizer is also an excellent agent for blending with other dry fertilizers to produce a complete analysis product.
What is a Granoblastic rock?
Granoblastic is an adjective describing an anhedral phaneritic equi-granular metamorphic rock texture. Granoblastic texture is typical of quartzite, marble, charnockites and other non-foliated metamorphic rocks without porphyroblasts.
Is amphibolite intrusive or extrusive?
Mafic igneous rocks (olivine, pyroxene, and the plagioclase feldspars) include basalt (extrusive) and gabbro (intrusive), while felsic igneous rocks (quartz, amphibole, mica, and the orthoclase feldspars) include granite (intrusive) and rhyolite (extrusive).
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 do you identify an amphibolite rock?
Amphibolite is a grouping of rocks composed mainly of amphibole and plagioclase, with little or no quartz. It is typically dark-colored and dense, with a weakly foliated or schistose (flaky) structure. The small flakes of black and white in the rock often give it a salt-and-pepper appearance.
How are greenschist facies formed?
Greenschists form by regional metamorphism of mafic igneous rocks, usually basaltic rocks, under greenschist facies metamorphism (usually produced by regional metamorphism, typically 300–450 °C and 1–4 kilobars).
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.
Is staurolite a metamorphic facies?
The chlorite and biotite zones represent greenschist facies metamorphism, and the garnet, staurolite, kyanite, and sillimanite zones represent amphibolite facies metamorphism. ... During this stage, much of the metamorphism took place.
What is the difference between a charnockite and a Granulite?
The major difference between these rocks is their nature, charnockites are igneous while granulites are metamorphic. ... While charnockites have a preserved igneous texture, and very commonly show hydration parageneses caused by magmatic fluids in the late magmatic stages (deuteric alteration).
Is charnockite a metamorphic rock?
charnockite, any member of a series of metamorphic rocks with variable chemical composition, first described from the state of Tamil Nadu in southern India and named for Job Charnock. The term is often limited to the characteristic orthopyroxene granite of the series.
What is Khondalite rocks?
Khondalite is a foliated metamorphic rock. In India, it is also called Bezwada Gneiss and Kailasa Gneiss. It was named after the Khond tribe of Odisha and Andhra Pradesh because well-formed examples of the rock were found in the inhabited hills of these regions of eastern India.
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