Formation of Amphibolite and Banded iron formation

Amphibolite

Banded iron formation

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1 Formation

1.1 Formation

Amphibolite is a coarse-grained metamorphic rock which forms by metamorphism of mafic igneous rocks like basalt and gabbro or from the metamorphism of clay-rich sedimentary rocks like marl or graywacke.

The banded iron layers are formed in sea water when oxygen is released by photosynthetic cyano-bacteria. The oxygen then combines with dissolved iron in ocean to form insoluble iron oxides, which precipitated out, forming a thin layer of banded iron formation on ocean floor.

1.2 Composition

1.2.1 Mineral Content

Amphibole, Andalusite, Biotite, Calcite, Epidote, Garnet, Hornblade, Kyanite, Magnetite, Olivine, Plagioclase, Pyroxene, Staurolite, Wollastonite

Hematite, Magnetite, Quartz

1.2.2 Compound Content

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

Fe, Iron(III) Oxide, Silicon Dioxide

1.3 Transformation

1.3.1 Metamorphism

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97% Igneous Rocks Rocks have it !

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19% Sedimentary Rocks Rocks have it !

1.3.2 Types of Metamorphism

Not Applicable

1.3.3 Weathering

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99% Igneous Rocks Rocks have it !

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78% Sedimentary Rocks Rocks have it !

1.3.4 Types of Weathering

Chemical Weathering, Mechanical Weathering

Chemical Weathering

1.3.5 Erosion

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92% Igneous Rocks Rocks have it !

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86% Sedimentary Rocks Rocks have it !

1.3.6 Types of Erosion

Chemical Erosion, Glacier Erosion, Sea Erosion, Wind Erosion

Coastal Erosion, Wind Erosion

Amphibolite and Banded iron formation Formation

Formation of rocks is a long process and hence, Amphibolite and Banded iron formation 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 Amphibolite and Banded iron formation, composition of Amphibolite and Banded iron formation and their transformation.