Formation of Gneiss and Anorthosite

Gneiss

Anorthosite

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1 Formation

1.1 Formation

Gneiss is a high grade metamorphic rock i.e. it has been subjected to higher temperatures and pressures than schist. It is formed by the metamorphosis of Gneiss forms from volcanic rock, shale or granitie.

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.

1.2 Composition

1.2.1 Mineral Content

Biotite, Chlorite, Feldspar, Garnet, Graphite, Hornblade, Micas, Muscovite or Illite, Quartz, Quartzite, Silica, Zircon

Amphibole, Clinopyroxene, Ilmenite, Magnetite, Olivine, Orthopyroxene

1.2.2 Compound Content

Aluminium Oxide, NaCl, CaO, Iron(III) Oxide, FeO, Potassium Oxide, Magnesium Carbonate, MgO, MnO, Phosphorus Pentoxide, Silicon Dioxide, Titanium Dioxide

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

1.3 Transformation

1.3.1 Metamorphism

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1.3.2 Types of Metamorphism

Impact Metamorphism

Cataclastic Metamorphism, Contact Metamorphism

1.3.3 Weathering

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1.3.4 Types of Weathering

Biological Weathering, Mechanical Weathering

Biological Weathering

1.3.5 Erosion

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1.3.6 Types of Erosion

Chemical Erosion, Coastal Erosion, Sea Erosion

Chemical Erosion, Wind Erosion

Gneiss and Anorthosite Formation

Formation of rocks is a long process and hence, Gneiss and Anorthosite 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 Gneiss and Anorthosite, composition of Gneiss and Anorthosite and their transformation.