Anorthosite

Classification：Igneous Rock

Basic pluton, mainly composed of plagioclase (>90%), coarse-grained structure, is the main component of lunar land on the lunar surface.

Anorthosite is composed of 90% or more mafic plutonic rocks. Dark minerals include various pyroxene, olivine and hornblende. Anorthosite has been distributed in the mainland and oceanic area. It has been generated from early Archaean to Cenozoic, but formed huge blocks in Precambrian area. Anorthosite is subhedral or its shape of coarse grain structure. The mineral and structural features of some rock masses are characterized by widespread recrystallization and strong deformation, but the Mitch Kamau La feldspar Anorthosite clearly indicates the characteristics of layered intrusive rocks. The bottom forms fine olivine gabbro, upwards to olivine (6 km thick), main Anorthosite, light colored gabbro and iron rich. Late stage differentiation strata.

Definition：
Anorthosite (anorthosite) is composed of 90% or more mafic plutonic rocks. Dark minerals include various pyroxene, olivine and hornblende. Plagioclase is generally elongated or medium feldspar. The dark minerals are orthopyroxene, clinopyroxene, hornblende and so on. The sum is less than 10%. Anorthosite is subhedral or its shape of coarse grain structure.

Introduction:
A composed of 90% or more mafic plutonic rocks. Dark minerals include various pyroxene, olivine and hornblende. Anorthosite has been distributed in the mainland and oceanic area. It has been generated from early Archaean to Cenozoic, but formed huge blocks in Precambrian area.

Species:
According to the occurrence and structure of Anorthosite, there are 3 main types of earth.
Stratiform invasive Anorthosite
For example, the Greenland Kell GAD intrusive rock mass, the Steele Voight complex in the United States and the South African Bush Wilde stratified rock mass contain a few meters thick Anorthosite, which interbedded with the pyroxenite or peridotite, and are considered to be formed by the crystallization differentiation of the basaltic magma. Plagioclase is mostly plagioclase (An65 ~ 85), and there are augite, olivine and a small amount of magnetite in its gap. These characteristics are the main basis for plagioclase crystal stacking hypothesis on the bottom of magma reservoir. The reason for the formation of this layered structure is that the relatively large proportion of pyroxene or olivine crystals deposit faster in magma and the possible limited yield of magma.
(2) huge block type Anorthosite
It is usually a vault. It can be divided into two subtypes: one is the irregular Anorthosite plot, and the other is Canada Saint John lake and micchi Mora feldspar Anorthosite. The long crystal (An45 ~ 63) large shape dark crystal shows blue and green sparks along special directions because of inclusions containing microcrystalline dark minerals. Dark minerals are often olivine, various pyroxene and Titano magnetite. In gneiss, the contact relationship between surrounding rock and surrounding rock is not obvious. The relationship between them is usually uncertain. The mineral and structural features of some rock masses are characterized by widespread recrystallization and strong deformation, but the Mitch Kamau La feldspar Anorthosite clearly indicates the characteristics of layered intrusive rocks. The bottom forms fine olivine gabbro, upwards to olivine (6 km thick), main Anorthosite, light colored gabbro and iron rich. Late stage differentiation strata. The other is a domed Anorthosite block, in New York, Adidas Lunda Ke feldspar type and Norway Anorthosite in egersund as an example. These Anorthosite often symbiotic with metamorphic metamorphic rocks and perilla granitoids in the granulite facies region, and the crystalline form of the feldspar (An23 ~ 48) is irregular and has an anti stripe feldspar structure. Olivine is rare in dark minerals, mainly composed of clinopyroxene and hematite. Many rock masses have strip or bedding, and often have the boundary zone of the gabbro Anorthosite, which is closely related to the intrusion of the surrounding rock, and contains the irregular elongated Anorthosite inclusion. The genesis of block type Anorthosite is probably related to the abnormal release of heat and volatiles from deep underground.
Modern oceanic crust type Anorthosite
It is found in the middle India ridge stratified igneous complex, which is mainly rich in Ti and Fe gabbro. It contains only about 5% depleted calcium and elongated Anorthosite. In addition, there are also the moon type Anorthosite. Compared with the same rock on earth, the breccia Anorthosite structure is very fine grained, which is considered to be caused by the impact of meteorites, or by the rapid crystallization of the impact melts. Non brecciate Anorthosite has a complete crystalline calcium feldspar, which is associated with a small amount of olivine, spinel, pyroxene, ilmenite and natural iron. The moon Anorthosite is stratiform, and is formed from plagioclase crystals from basalt melt. These plagioclase rich rocks and Anorthosite constitute the main part of the lunar surface.