Physics of Two Phase Media: Evolution of the Early Earth

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A major puzzle has arisen concerning earliest Earth: How do we reconcile the physical arguments for a fully molten initial state with the geochemical arguments that the differentiations implied by this state are incompatible with the current Earth? One possible reconciliation lies in a better understanding of the physics of two phase media (e.g., partial melts) since many of the common preconceptions about how such media behave have never been tested quantitatively. Numerical fluid dynamical experiments will include the following: (1) Behavior of a vigorously converting partial melt undergoing cooling: To what extent does the melt escape rather than be quenched it situ? This pertains to the macroscopic differentiation of perovskite from coexisting melt. (ii) Convection of a partial melt in the presence of a density cross-over (where liquid density = solid density). To what extent is melt expelled? Can an olivine-rich "perched" layer develop ;at 250 to 500 km depth? (iii) Early mantle dynamics in the presence of core formation. To what extent can percolating iron drive silicate melt downwards? To what extent can the iron drive compositional convection that destroys primordial mantle layering? (iv) Mixing created by large impacts. (v) Mixing created by later partial melting in a stably stratified environment.