migmatite A coarse-grained, heterogeneous mixed rock consisting of: (a) a high-grade metamorphic component with a gneissose texture (see METAMORPHIC GRADE); and (b) an igneous component with a granite mineralogy and a foliated or unfoliated texture (see FOLIATION).
Why is Migmatite only half metamorphic rock?
Many migmatites probably represent the partial fusion of the metamorphic host during extreme metamorphism; the components of the rock with the lower melting temperatures are fused and gather to produce the streaks of granite. The migmatites of some Precambrian metamorphic terrains may be the result of this process.
What is a Migmatite quizlet?
Migmatite. a rock exhibiting both igneous and metamorphic characteristics. Such rocks may form when light-colored silicate minerals melt and then crystallize, while the dark silicate minerals remain solid. Minerology.
How do rocks undergo metamorphism?
Metamorphism occurs because some minerals are stable only under certain conditions of pressure and temperature. When pressure and temperature change, chemical reactions occur to cause the minerals in the rock to change to an assemblage that is stable at the new pressure and temperature conditions.
Is migmatite an igneous rock?
A migmatite is a metamorphic rock formed by anatexis that is generally heterogeneous and preserves evidence of partial melting at the microscopic to macroscopic scale. Migmatites represent the transition from metamorphic to igneous rocks in the rock cycle.
What is a migmatite in geology?
Migmatites are heterogeneous, medium- to high-grade metamorphic rocks with at least one component formed by partial melting. As migmatites form under P–T conditions common in the middle and lower crust, they are widespread and likely to be encountered in the field.
How are gneisses and migmatites related?
The two rock types are certainly relatives, so to speak. If a gneiss experiences just slightly higher temperatures, it may partially melt and become a migmatite.
How is migmatite rock formed?
Migmatites form under extreme temperature and pressure conditions during prograde metamorphism, when partial melting occurs in metamorphic paleosome. … If present, a mesosome, intermediate in color between a leucosome and melanosome, forms a more or less unmodified remnant of the metamorphic parent rock paleosome.
What is migmatite used for?
Migmatites have an attractive appearance, often being marked with irregular small stripes or patches of contrasting shades ranging from almost white to dark grey, and are widely used as building stone, sometimes being polished for ornament.
What distinguishes a Migmatite from other high grade metamorphic rocks?
temperatures Migmatite is a rock at the frontier between igneous and metamorphic rocks. Migmatites form under extreme temperature conditions during prograde metamorphism, where partial melting occurs in pre-existing rocks. … It is now a much harder rock similar to the situation of a meta-sandstone or quartzite.
What is a Hornfels rock?
Hornfels is medium-to-coarse crystalline metamorphic rocks formed out of contact metamorphism, dark color, and rich in silicates with granoblastic and porphyroblastic texture.
What is the partially melted rock that is a transition between metamorphic and igneous rocks?
A rock with this texture is called gneiss. Since gneisses form at the highest temperatures and pressures, some partial melting may occur. This partially melted rock is a transition between metamorphic and igneous rocks called a migmatite.
Which is a metamorphic rock?
Common metamorphic rocks include phyllite, schist, gneiss, quartzite and marble. Foliated Metamorphic Rocks: … Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned.
What is metamorphism quizlet?
Metamorphism. Metamorphism is the transformation. of preexisting rock into texturally or. mineralogically distinct new rock as a result of high temperature, high pressure, or both..but without the rock melting in the process. Solid state.
What is the different combination of a mineral formation?
The four main categories of mineral formation are: (1) igneous, or magmatic, in which minerals crystallize from a melt, (2) sedimentary, in which minerals are the result of sedimentation, a process whose raw materials are particles from other rocks that have undergone weathering or erosion, (3) metamorphic, in which …
Where is migmatite rock found?
A migmatite is a rock body that has been heated so much that some of the minerals in it have started to melt and segregate from other minerals with a higher melting temperature. Migmatites are often found at the base of crustal mountain blocks, where they have been heated by the pressure of the overlying mountains.
What is the texture of migmatite?
Migmatite – a high grade Barrovian metamorphic rock that has begin to fractionally melt. In appearance it looks like a gneiss intermixed with patches and splotches of phaneritic (coarse grained) igneous texture.
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.
Where is mylonite formed?
shear zones Mylonites form deep in the crust where temperature and pressure are high enough for the rocks to deform plastically (ductile deformation). Mylonites form in shear zones where rocks are deformed because of the very high strain rate.
Where should Migmatite be placed in the rock cycle?
Migmatite is a rock that straddles the fence separating metamorphic and igneous. Like the example we saw yesterday, it’s a rock on the cusp of one of the major transitions in the rock cycle.
What is the use of quartzite rock?
As a decorative stone, it is used to cover walls, pools, garden pathways, backyards, or stair treads. Construction – Quartzite has high abrasion resistance and durability so it’s a popular stone in the construction industry. It is used as road aggregate and concrete aggregate.
What is Charnockite rock?
Charnockite (/ˈtʃɑːr. nəˌkaɪt/) 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 meaning of schist in English?
: a metamorphic crystalline rock that has a closely foliated structure and can be split along approximately parallel planes.
What is Metaconglomerate used for?
A metamorphic rock formed by recrystallization of a conglomerate. This category is also used for meta-conglomerate.
How do you pronounce Migmatite?
Where can you find Blueschist?
This is a ‘low temperature, high pressure’ prograde metamorphic path and is also known as the Franciscan facies series, after the west coast of the United States where these rocks are exposed. Well-exposed blueschists also occur in Greece, Turkey, Japan, New Zealand and New Caledonia.
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