Crystallizing the terrestrial magma ocean: thermo- and geodynamics

岩浆海洋的冷却和结晶可能起源于月球形成的影响，确定了固体地幔的初始热和化学结构，从而为随后的内部演化的热成分对流控制的条件。要模拟岩浆海洋结晶所产生的成分，就需要详细描述整个地幔压力范围内的液相线和相图、晶体和熔体之间主要元素的分配系数以及残余液体和新形成固体的密度。我们将通过进行有针对性的多砧高压实验，将MgO-SiO2系统中熔融相关系的热力学模型扩展到FeO-MgO-SiO2（FMS）和CaO-MgO-SiO2（CMS）系统。重点将是更好地约束液相线的MgO 3侧的共晶在FeO的存在下，并获得可靠的数据，共晶在CMS系统中，其中所有主要相的存在下：方镁石，钙钛矿和钙钛矿。这些实验也将被用来建立分配系数，特别是铁，熔体和下地幔阶段之间。这些额外的约束条件将被纳入岩浆海洋分离结晶模型，建立陆地岩浆海洋的结晶序列和密度结构。新获得的熔体密度在CMS，FMS和Al 2 O3轴承地幔组合物的MD结果将包括计算结晶岩性的浮力。由此产生的密度分层将为我们提供一个物理和化学上一致的图片的热量和成分状态的地幔后立即凝固，并将作为一个新的起点的内部动力学的数值模型。我们将利用这些模型来模拟地幔和核心在整个地球历史的耦合演化，并从一个新的角度描述基本过程，如板块构造和磁场产生的开始和维持，以及大规模地球化学水库的形成和随后的混合。

Cooling and crystallization of the magma ocean that likely originated from the Moon-forming impact set the initial thermal and chemical structure of the solid mantle and thus the conditions for the subsequent evolution of the interior controlled by thermo-compositional convection. Modelling of the composition resulting from magma ocean crystallization requires a detailed description of the liquidus and phase diagram - over the entire mantle pressure-range-, of the distribution coefficients of major elements between crystals and melts, and of the density of residual liquids and newly formed solids. We will extend thermodynamic models of melting phase relations in the MgO-SiO2 system to the FeO-MgO-SiO2 (FMS) and CaO-MgO-SiO2 (CMS) systems by performing targeted multianvil high-pressure experiments. The focus will be on better constraining the liquidus on the MgSiO3 side of the eutectic in the presence of FeO and to obtain reliable data on the eutectic in the CMS system in which all major phase of the lower exists: periclase, bridgmanite and Ca-perovskite. These experiments will also be used to establish partition coefficients, in particular of Fe, between the melt and lower mantle phases. The additional constraints will be incorporated into a model of fractional crystallization of the magma ocean, establishing the crystallization sequence and the density structure of the terrestrial magma ocean. Newly obtained MD results on melt densities in the CMS, the FMS and Al2O3-bearing mantle compositions will be included to compute buoyancy of crystallizing lithologies. The resulting density stratification will provide us with a physically and chemically consistent picture of the thermal and compositional state of the mantle immediately after its solidification and will serve as a novel starting point for numerical models of the dynamics of the interior. We will employ these models to simulate the coupled evolution of the mantle and core over the entire history of the Earth and characterize from a new perspective fundamental processes such as the onset and maintenance of plate tectonics and magnetic field generation, and the formation and subsequent mixing of large scale geochemical reservoirs.