Changes

==The Earth’s Crust==

==The Earth’s Crust==

The Earth’s crust triggers the questions of Earth scientists regarding its formation and evolution through time. Continental and oceanic crust makes up nearly three-fourths of the Earth’s body, providing sources of sediment and [[basement]] of basins. Continental crust, chemically, tends to have more felsic mineralogical composition than oceanic one.

The Earth’s crust triggers the questions of Earth scientists regarding its formation and evolution through time. Continental and oceanic crust makes up nearly three-fourths of the Earth’s body, providing sources of sediment and [[basement]] of basins. [[Continental crust]], chemically, tends to have more felsic mineralogical composition than oceanic one.

Divergent plate boundary displays the phenomenon of sea-floor spreading. Mid-Oceanic Ridge (MOR) is the place where magma from below the Earth emerges and crystallizes as oceanic crust. The spreading of the sea-floor causes decompression, triggering partial melting of the source rock. Generation of oceanic crust in MOR enables it to be the youngest crust making up the Earth. No oceanic crust is found to be older than Jurassic.

Divergent plate boundary displays the phenomenon of sea-floor spreading. Mid-Oceanic Ridge (MOR) is the place where magma from below the Earth emerges and crystallizes as oceanic crust. The spreading of the sea-floor causes decompression, triggering partial melting of the source rock. Generation of oceanic crust in MOR enables it to be the youngest crust making up the Earth. No oceanic crust is found to be older than Jurassic.

Primitive magma generated from the mantle wedge ascent to the boundary of crust and mantle. Due to density contrast, magma from mantle wedge underplates at the base of crust and experiences melting, assimilation, storage, and homogenization (MASH). Assimilation occurs because the crust is molten and enriching the composition of ascending magma. Winter<ref name=Winter>Winter, J. D. 2001, An Introduction to Igneous and Metamorphic Petrology. New Jersey: Prentice-Hall Inc.</ref> defines fractionation as mechanical separation of materials with distinct phases. Simplified explanation of fractional crystallization is represented in Bowen reaction series. Magma will ascent from the base of the crust when faults creating fractures for magma migration. This requirement may occur in thinning area.

Primitive magma generated from the mantle wedge ascent to the boundary of crust and mantle. Due to density contrast, magma from mantle wedge underplates at the base of crust and experiences melting, assimilation, storage, and homogenization (MASH). Assimilation occurs because the crust is molten and enriching the composition of ascending magma. Winter<ref name=Winter>Winter, J. D. 2001, An Introduction to Igneous and Metamorphic Petrology. New Jersey: Prentice-Hall Inc.</ref> defines fractionation as mechanical separation of materials with distinct phases. Simplified explanation of fractional crystallization is represented in Bowen reaction series. Magma will ascent from the base of the crust when faults creating fractures for magma migration. This requirement may occur in thinning area.

Assimilation and fractional crystallization of magma in the continents depends on the type of the crust. Continental crust itself is generally divided as upper and lower parts, represented with distinctive composition as previously discussed. With several possibilities of interaction, assimilation and fractional crystallization of magma have different Sr, Nd, Pb, and O isotopic signature. The use of Sr, Nd, and Pb data for interpreting young continental crust may trigger misleading result. Since young continental crust may have slightly different composition with the primitive magma, the data will show that contamination doesn’t occur. Winter<ref name=Winter /> states that assimilation and fractional crystallization in the deep-level generates magma with higher concentrations of K2O, Rb, Cs, Ba, Th, and Light Rare Earth Elements (LREE). Assimilation in active continental margin depends on temperature, composition, and thickness of the crust.

Assimilation and fractional crystallization of magma in the continents depends on the type of the crust. [[Continental crust]] itself is generally divided as upper and lower parts, represented with distinctive composition as previously discussed. With several possibilities of interaction, assimilation and fractional crystallization of magma have different Sr, Nd, Pb, and O isotopic signature. The use of Sr, Nd, and Pb data for interpreting young continental crust may trigger misleading result. Since young continental crust may have slightly different composition with the primitive magma, the data will show that contamination doesn’t occur. Winter<ref name=Winter /> states that assimilation and fractional crystallization in the deep-level generates magma with higher concentrations of K2O, Rb, Cs, Ba, Th, and Light Rare Earth Elements (LREE). Assimilation in active continental margin depends on temperature, composition, and thickness of the crust.

===Sedimentary Petrology===

===Sedimentary Petrology===