Suspension in convective layers and style of differentiation of a terrestrial magma ocean

Recent physical theories for the formation of the Earth suggest that about 4.5 b.y. ago the mantle of the Earth was partially or completely molten. Fractional crystallization of this hypothetic magma ocean would result in a strong chemical stratification of the Earth's mantle. Such a scenario is controversial from the geochemical point of view. However, it has been noted that the simple scenario of fractional crystallization could be avoidable in a convective magma ocean if crystals remain suspended. In this paper, the problem of suspension is developed with the help of an energetic approach: convection must do some work against gravitational settling. Three regimes of convective suspensions are distinguished. Absolute or complete sedimentation occurs when the energy dissipation due to the settling exceeds the heat loss from the convective layer. This is possible only in large-scale systems like magma oceans and implies that cooling can proceed only together with sedimentation, crystallization, and a decrease in the liquidus temperature at a constant pressure. -from Authors