Temperatures and Seismic Discontinuities in the Earth
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By modifying Uffen's approach, which relates the Einstein-Debye theory of solids to Lindemann's melting criterion, the relative melting temperature distributions in each major division of the Earth's interior are calculated from observed seismic velocities. With further assumptions, the melting temperature profile and three possible present temperature distributions inside the Earth are also proposed. By extrapolation, this approach yields a temperature of ≤8, 000 K at the center of the Earth. On the basis of the melting temperature gradients at each major seismic discontinuity, it is concluded that only the 220- and 400-km seismic discontinuities are consistent with a phase transition possessing a positive Clapeyron slope, whereas all other seismic discontinuities are found to be consistent with either a phase transition having a negative slope or a chemical change. The outer-inner core boundary is not a simple melting phenomenon. These conclusions have been reached independently of all previous studies that used elastic and thermal properties of the Earth and of the predicted compositions for the various parts of the Earth.
- Earth, Planets and Space
Earth, Planets and Space 45(4), 247-263, 1997-08
The Seismological Society of Japan, The Volcanological Society of Japan , The Geodetic Society of Japan