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Comparison of earth - Comparison of earth's crust with...

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Comparison of earth's crust with chondritic meteorites We can compare the proportions of minerals in the crust to that in chondritic meteorites as representatives of presumably undifferentiated (unfractionated) material from the relatively homogeneous formation of the original solar system material. We wouldexpect to see more lightewouldexpect to see more lighter material in the crust because of the fractionation: SiO 2 MgO FeO Chondrites 0.380 0.238 0.124 Crust 0.587 0.049 0.052 In the interior of the earth not only are Fe and Mg more abundant, but so are ions of the same size (c. 0.08nm radius) such as Co, Ni and Mn. Elements which do not substitute (e.g. radii 0.1- 0.15nm, such as K, Cs, Ba, Th, and U) tend to be more abundant near the surface. [Note the Th and U - does this mean we would only expect to see these radioactive elements now near the surface?] Reasons for density increase with depth The increase in density is partly due to the increase in pressure with depth.
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