Physics of Two Phase Media: Evolution of the Early Earth

关于最早的地球出现了一个主要的谜题：我们如何调和关于完全熔融的初始状态的物理论点和由这种状态所暗示的差异与当前地球不相容的地球化学论点？一种可能的调和在于更好地理解两相介质(例如部分熔体)的物理学，因为许多关于这种介质行为的常见先入为主的概念从未进行过定量测试。数值流体动力学实验将包括以下内容：(1)部分熔体在冷却过程中剧烈转化的行为：熔体在多大程度上逃逸而不是被就地冷却？这与钙钛矿与共存熔体的宏观区别有关。(Ii)存在密度交叉(其中液体密度=固体密度)时部分熔体的对流。熔体被排出的程度有多大？在250到500公里的深度，能形成富含橄榄石的“栖息层”吗？(3)存在核形成时的早期地幔动力学。渗入的铁能在多大程度上驱动硅酸盐熔体向下移动？铁能在多大程度上驱动成分对流，从而破坏原始地幔分层？(4)大撞击造成的混合。(V)在稳定的分层环境中由后来的部分熔融产生的混合。

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.