Why a Migmatite is both an igneous and metamorphic rock?
Why a Migmatite is both an igneous and metamorphic rock?
Granites are igneous rocks that form from magma, which is melted rock. Migmatite rock lies at the interface between metamorphic and igneous rock. What I mean by this is that migmatites are metamorphic rocks formed via melting of rock — but melted rock is magma — and igneous rock comes from magma.
What minerals are in Migmatite?
(1) Petrologic Property
| Type | Subtype | Mineral composition |
|---|---|---|
| Regional metamorphic rock | Plagioclase leptite | Biotite (amphibolite), plagioclase, quartz, epidote |
| Plagioclase gneiss | Plagioclase, quartz, biotite | |
| Amphibolite (plagioclase amphibolite) | Andesine, hornblende | |
| Migmatite | Quartz, feldspar, less biotite |
What is migmatite rock?
migmatite, in geology, rock composed of a metamorphic (altered) host material that is streaked or veined with granite rock; the name means “mixed rock.” Such rocks are usually gneissic (banded) and felsic rather than mafic in composition; they may occur on a regional scale in areas of high-grade metamorphism.
What is a migmatite rock?
What are slate stones?
Slate is a fine-grained, foliated, homogeneous metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade regional metamorphism. It is the finest grained foliated metamorphic rock. It may mean a single roofing tile made of slate, or a writing slate.
Why is migmatite only half metamorphic rock?
Commonly, migmatites occur below deformed metamorphic rocks that represent the base of eroded mountain chains, commonly within Precambrian cratonic blocks, Migmatites form under extreme temperature and pressure conditions during prograde metamorphism, when partial melting occurs in metamorphic paleosome.
Why is Migmatite only half metamorphic rock?
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.
Why are migmatites important to geologists?
Because migmatites are hybrid metamorphic-igneous rocks , they are important rocks for geologists to study in order to better understand how rocks melt and how these melts migrate and eventually become igneous rocks.
DESCRIPTION: Migmatites are macroscopically composite rocks, most of which consist of a dark colored amphibolite or biotite gneiss intimately mixed with a light colored rock of granitic or granodioritic composition.
What is the relationship between migmatites and granitic melts?
The exact relationship– if any– between migmatites and large bodies of melt is ambiguous and still debated amongst geologists, but migmatites do provide clear evidence that granitic melts (and also other types of melts) can be produced through partial melting of metamorphic rocks.
Should we call them migmatites?
In practice, it seems best for anyone other than petrologists working directly with these rockst to call them merely migmatite and to include descriptions of the chief component rocks.
