Formation of Anorthosite and Nephelinite

Anorthosite

Nephelinite

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1 Formation

1.1 Formation

Anorthosite is a phaneritic, intrusive igneous rock which is characterized by a predominance of plagioclase feldspar which is almost 90–100%, and a minimal mafic component.

Nephelinite is a fine-grained, hard rock which is a type of metasomatite, essentially altered basalt. It forms with or without crystallization, either below the surface as intrusive rocks or on the surface as extrusive rocks.

1.2 Composition

1.2.1 Mineral Content

Amphibole, Clinopyroxene, Ilmenite, Magnetite, Olivine, Orthopyroxene

Clinopyroxene, Nepheline, Plagioclase

1.2.2 Compound Content

Ca, CaO, Chromium(III) Oxide, MgO, Sulfur Trioxide

Ca, CaO, Carbon, Cl, MgO

1.3 Transformation

1.3.1 Metamorphism

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1.3.2 Types of Metamorphism

Cataclastic Metamorphism, Contact Metamorphism

Contact Metamorphism

1.3.3 Weathering

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1.3.4 Types of Weathering

Biological Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

1.3.5 Erosion

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1.3.6 Types of Erosion

Chemical Erosion, Wind Erosion

Chemical Erosion, Water Erosion, Wind Erosion

Anorthosite and Nephelinite Formation

Formation of rocks is a long process and hence, Anorthosite and Nephelinite formation sounds very interesting. According to the formation, all rocks are divided into :Igneous Rocks, Fossil Rocks and Metamorphic Rocks. Igneous rocks form by crystallization of magma or lava. The magma is made up of various components of pre-existing rocks which have been subjected to melting either at subduction zones or within the Earth's mantle. Igneous rocks are generally seen at mid ocean ridges or in intra-plate hotspots. Sedimentary rocks are formed when sediments accumulate gradually. As the sediments are buried they get compacted as more and more material is deposited on top. Eventually the sediments become so dense that they form a rock. Metamorphic rocks are rocks which once existed as igneous or sedimentary rocks but have been subjected to varying degrees of pressure and heat within the Earth's crust. Get to know all about formation of Anorthosite and Nephelinite, composition of Anorthosite and Nephelinite and their transformation.