Element partitioning at ultrahigh pressure and chemical evolution of the Earth's interi

本文测定了镁钙钛矿与岩浆、镁钙钛矿与铁液、岩浆与铁液、镁橄榄石与铁液之间亲石、亲铁元素的分配系数。铁液-岩浆分配实验结果表明，Fe、Co、Ni在岩浆-铁液间的分配系数随压力的增加而减小，Mn随压力的增加而增大，而这些分配系数随温度的增加而增大。我们还研究了硫和碳在岩浆-铁液分配中的作用。研究发现，当体系中存在少量硫时，Mo和W的分配系数发生变化，特别是W;含硫体系中的W（和Mo）比不含硫体系中的W（和Mo）更容易进入硅酸盐岩浆中。Mo和W的分配行为表明，在没有硫的情况下，地幔中W和Mo的丰度与核幔平衡是一致的。我们还进行了地幔矿物Mg_2SiO_4-Fe_2SiO_4、Mg_2SiO_4-Mg_3Al_2Si_3O_4和Mg_2SiO_4-H_2O系统的熔融和相变实验<12>。这些数据为研究过渡带和下地幔上部深部岩浆活动和水量提供了基础信息。

In this work, we determined the partition coefficients of lithophile and siderophile elements between Mg-perovskite and magma, Mg-perovskite and molten iron, magma and molten iron, and magnesiowustite and molten iron. The experiments of the partitioning between molten iron and magma indicate that the partition coefficients between magma and molten iron implies that those for Fe, Co, and Ni decrease with increasing pressure, whereas that of Mn increase with increasing pressure, and these partition coefficients increases with increasing temperature. We also studied the effect of sulfur and carbon for the partitioning between magma and molten iron. We found that the partition coefficients of Mo and W,especially W,change with existence of a small amount of sulfur in the system ; W (and Mo) n the sulfur containing system tends to enter into the silicate magma compared to those in sulfur free system. The present partitioning behavior of Mo and W implies that the present mantle abundance of W and Mo is consistent with the core-mantle equilibrium without sulfur in the system. This suggests that sulfur is not likely to be a candidate for the light element in the core.We also conducted the melting and phase transition experiments of the mantle minerals, such as the Mg_2SiO_4-Fe_2SiO_4, Mg_2SiO_4-Mg_3Al_2Si_3O_<12>, and Mg_2SiO_4-H_2O systems. These data provide basic information on the deep seated magmatism and the amount of water in the transition zone and the upper most part of the lower mantle.