Abstract:The core paradox reconsidered​

W. Ullmann and U. Walzer. The core paradox reconsidered. Phys. Earth Planet. Int., 22:204-210, 1980.

The core paradox reconsidered

W. Ullmann and U. Walzer

Abstract

Using a new theory of the volume dependence of Grüneisen's parameter we have reconsidered the core paradox. If the melting-point curve according to Higgins and Kennedy (1971) applies, and if the inner and outer cores are chemically equal, thermo-convective dynamos are impossible throughout the outer core. Thermal convection would be prevented even in the 200–300 km thick layer at the bottom of the outer core where, for constant γ-values, thermal convection is possible. Using Leppaluoto's (1972) and Boschi's (1975) melting-point curves and the volume-dependent γ, thermal convection is possible. Liu's (1975) melting-point curve shows the phenomenon of polymorphism of iron. The curve of adiabatic temperature computed by using our theory runs very closely above this, and consideration of the electronic contribution to Grüneisen's parameter produces a curve which runs very close below Liu's curve. By using the other melting-point curves mentioned above the conclusions are not altered. Thus we see that the core paradox exists not only in the case of Higgins' and Kennedy's (1971) melting-point curve and, despite claims to the contrary, this problem is unresolved even today. Various possibilities to circumvent the paradox are discussed.

Key words: Earth, Earth's core, core paradox, magnetic field, melting point, melting temperature, high pressure, dynamo, Grüneisen parameter, outer core, convection, thermal convection, electronic contribution, equation of state, thermodynamics, adiabatic temperature, geodynamic field, phase boundaries, adiabat, convection, iron

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