Abstract
The Earth is cooling and the solid inner core is growing as the outer core freezes. The outer core is composed primarily of iron but it contains a small fraction of some lighter constituent. Freezing such a mixture leaves most of the light constituent in the remaining fluid (the outer core), the frozen solid (the inner core) being nearly pure iron. The fluid close to the freezing interface [the inner-core boundary (ICB)] is therefore rich in the light constituent. This effect together with the latent heat released by the freezing process produces buoyant fluid at the ICB. This fluid rises, stirring the outer core and so is the source of the energy required to maintain the geomagnetic field against ohmic losses. This picture of the evolution of the Earth’s core is now widely accepted, but the consequences of the core being a freezing mixture have yet to be fully explored. Here we review the background to this theory and discuss its consequences for the structure of the inner core, the structure of the complex freezing region at the ICB, the flow in this region and the flow in the outer core.
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© 1989 Kluwer Academic Publishers
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Fearn, D.R. (1989). Compositional Convection and the Earth’S Core. In: Lowes, F.J., Collinson, D.W., Parry, J.H., Runcorn, S.K., Tozer, D.C., Soward, A. (eds) Geomagnetism and Palaeomagnetism. NATO ASI Series, vol 261. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-0905-2_25
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DOI: https://doi.org/10.1007/978-94-009-0905-2_25
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