Formation of Dolomite and Banded iron formation

Dolomite

Banded iron formation

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1 Formation

1.1 Formation

Dolomite rocks are originally deposited as calcite or aragonite rich limestone, but during diagenesis process, the calcite or aragonite is transformed into dolomite.

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

Clay Minerals, Pyrite, Quartz, Sulfides

Hematite, Magnetite, Quartz

1.2.2 Compound Content

NaCl, CaO, Carbon Dioxide, Magnesium Carbonate, MgO

Fe, Iron(III) Oxide, Silicon Dioxide

1.3 Transformation

1.3.1 Metamorphism

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1.3.2 Types of Metamorphism

Burial Metamorphism, Cataclastic Metamorphism, Contact Metamorphism

Not Applicable

1.3.3 Weathering

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1.3.4 Types of Weathering

Not Applicable

Chemical Weathering

1.3.5 Erosion

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1.3.6 Types of Erosion

Not Applicable

Coastal Erosion, Wind Erosion

Dolomite and Banded iron formation Formation

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