Pressure effect on element partitioning between minerals and silicate melt

通过高压熔融实验，研究了26种微量元素(稀土元素Sc、Y、Ga、In、Sr、Li、Rb、Cs、Ce、Zr、Hf)在硅酸盐熔体与共生矿物(石榴石、CPX、钙钛矿、钾矿、钙钙钛矿、镁钙钛矿)之间的分配规律。在具有相同价态的离子中，人们认为分配系数最大的离子在任何压力条件下都不会改变。然而，目前的实验结果清楚地表明，它们可以在非常高的压力条件下改变。这种影响在价态较小的离子中较大。例如，在一价离子中，K和Rb在常压条件下是典型的不相容元素，但在超高压条件下，它们的分配系数可能比其他一价离子大。

High pressure melting experiments on rocks doped with 26 trace elements (rare earth elements, Sc, Y, Ga, In, Sr, Li, Rb, Cs, Ce, Zr, Hf) were performed from 3 to 25 GPa, and the partitioning of elements between silicate melt and coexisting minerals (Garnet, CPx, Merwinite, K-hollandite, Ca-perovskite, Mg-perovskite) were investigated. Among ions which have the same valence, it has believed that the ion which has the maximum partition coefficient will not change under any pressure conditions. The present experimental results, however, are clearly showing that they can change under very high pressure conditions. This effect is larger in the ions which have smaller valence. For example, among monovalent ions, K and Rb are representative incompatible elements at normal pressure conditions, but their partition coefficients can be larger than other monovalent ions under ultra-high pressure conditions.