岩浆洋金属-硅酸盐熔体的钾元素分配和同位素分馏研究

类地行星最重要的初始分异是核幔分异，这个行星尺度过程决定了行星地幔的基本成分和结构。核幔分异过程中Fe-Ni金属由于密度较大下沉到岩浆洋底部形成地核，亲铁元素分配到地核中。随着研究的深入，除了亲铁元素外，其他元素（如碱金属）也可以分配到地核中。作为碱金属之一，K在地核中的分配可以提供解决地核发电机的能量来源问题。然而，地核中的K含量是个具有争议的问题。尽管争议存在，高温高压实验观察事实在金属-硅酸盐相平衡的金属相中检测到K的分配，而两相平衡下的K同位素分馏尚未研究。K元素和同位素在金属-硅酸盐相平衡中的地球化学行为，是应用K元素和同位素研究行星核幔分异的基础。本项目拟开展高温高压实验，研究K在复杂成分金属相-硅酸盐相中的分配和同位素分馏，获得不同实验条件下K元素和同位素在硅酸盐和金属相的分配系数，评估金属相成分对分配系数的影响，为核幔分异过程提供K元素地球化学制约。

The most important process for early terrestrial planets is core-mantle differentiation, which determines the basic composition and structure of the mantle. The iron and nickel sank to the bottom of magma ocean to form the core. Siderophile elements were also participated to the core. Besides the siderophile elements, other light elements such as alkaline elements, also have the possibility to enter the core. Potassium, as one of the alkaline elements, is thought to exist in the early core. Potassium existence in the core may play a key role in driving the geodynamo. The content of K in the core is under debate, although K has been detected in the metal phase after high pressure-temperature experiments. Until now, the K isotopes have not been studied during metal-silicates melts and it should be a critical factor to assess core-mantle differentiation process. The project aims to carry out series of high pressure-temperature experiments to study the coefficient of K and K isotopes between metal and silicate melts under complex systems. The obtained data would be used to trace core-mantle differentiation process of terrestrial planets.