Formation of Banded iron formation and Coquina

Banded iron formation

Coquina

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1 Formation

1.1 Formation

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.

Coquina is a sedimentary rock which is formed when billions of small clam-like seashell, called Coquina, or cockleshell are die and hence are deposited, buried and turns into a rock when pressure is applied.

1.2 Composition

1.2.1 Mineral Content

Hematite, Magnetite, Quartz

Apatite, Augite, Bronzite, Calcite, Chert, Chlorite, Clay Minerals, Epidote, Feldspar, Garnet, Micas, Muscovite or Illite

1.2.2 Compound Content

Fe, Iron(III) Oxide, Silicon Dioxide

CaO, Carbon Dioxide, Iron(III) Oxide, MgO

1.3 Transformation

1.3.1 Metamorphism

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1.3.2 Types of Metamorphism

Not Applicable

1.3.3 Weathering

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1.3.4 Types of Weathering

Chemical Weathering

Biological Weathering, Chemical Weathering, Mechanical Weathering

1.3.5 Erosion

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1.3.6 Types of Erosion

Coastal Erosion, Wind Erosion

Coastal Erosion, Sea Erosion, Water Erosion, Wind Erosion

Banded iron formation and Coquina Formation

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