抄録
Chemical structure of the earth's mantle is discussed under the assumptions that (1) chemical equilibrium and hydrostatic equilibrium are attained; (2) it is isothermal and incompressible. Based upon these assumptions, the distribution of chemical elements would be controlled by differences in their chemical affinities as well as by gravitational separation due to their density differences. Calculation of the equilibrium distribution of FeO-MgO-Fe-SiO2 system, it is concluded that FeO would increase with depth, reach maximum at a depth of several hundred kilometers, and then would decrease toward the earth's center. This result suggests the origin and the physical property of Jeffrey's 20° discontinuous layer.
