Granulite

Classification：Metamorphic Rock

At present, there is a different understanding of the definition of granulite, which is generally considered to be a granulite phase change rock. Some people think it should be renamed, but generally, granulite is used in scientific research.

Granulite, is a metamorphic rock and is a product of metamorphism in the middle and high regions. It is a regional metamorphic rock characterized by PERILITE. They are mainly distributed in Archean to early Proterozoic metamorphic rocks. Eastern Hebei and Western Liaoning are more developed. It is often rich in gold, silver, chromium, nickel, platinum, copper, lead, boron, graphite, piezoelectric quartz, gem, mica, rutile, apatite and other minerals.

Formation:
Granulite is a regional metamorphic rock formed at high temperature and high pressure. The temperature is about 700-900 degrees, the pressure is 0.7-1.2GPa, which is equivalent to the depth of underground 25-40km. The rock of the deepest metamorphic degree of granulite, with regard to its cause, is generally believed that the rock originally located in the upper part of the crust was gradually buried deep underground by tectonic movement, which was formed by high temperature metamorphism. After 1970s, some geologists thought that the magma derived from the upper mantle rose and invaded the bottom of the crust and metamorphosed under high temperature and high pressure. There is another view that the protolith is the product of the melting of oceanic plate subduction to the deep crust.

Form：
Weiss was first named in 1803. It is mainly composed of feldspar, quartz, pyroxene (xanthan pyroxene, diopside, etc.), sometimes containing garnet, sillimanite, kyanite and so on. The dark minerals in the rocks are mainly anhydrous minerals such as pericene, diopside and pomegranate, and hornblende and biotite are mainly non - or basically non - hydrous minerals. Light colored minerals are mainly plagioclase, striped feldspar, anti stripe feldspar and quartz, sometimes containing sillimanite, cordierite and so on. Water bearing minerals in rocks are unstable, which are generally not contained or contained. With coarse grained granite crystal texture, schistosity structure is not clear, massive structure. They are typical rocks of granulite facies metamorphism, and different types of granulites can appear because of their different compositions.

Dark colored Granulite:
(MELANOGRANULITE) or basic granulite (basic granulite). Dark minerals (xperite, diopside and hornblende) contents are 30% - 85%.

Light colored Granulite:
(leucogranulite) or acidic granulite (acidic granulite). The content of dark minerals is less than 30%. Some of them are further divided into dark granulite, medium granulite (mesogranulite) and light colored granulite. It is generally believed that the metamorphism belongs to the typical granulite facies. There is still a different understanding of the definition of granulite at present: some people think that the content of dark minerals in granulite is not more than 30%; some people think that the dark minerals of granulite should be mainly perilla pyroxene; some advocate that the metamorphic rocks with typical granulite facies are called granulites. Some people also include granulite facies metamorphic rocks (except marble and quartzite), including xperite and no xperite.