High-pressure on the structure and dynamics of the deep earth's interior.

建立了Mg_2SiO_4-Fe_2SiO_4体系中橄榄石改性尖晶石和尖晶石后相变的详细相图。地幔尖晶石在小于4 km的深度间隔内解离成钙钛矿（Pv）和镁武矿（Mw），使得650 km的不连续非常明显。该特征提供了650 km深度的地幔温度定点，并提出了标准的上地幔温度剖面。分析了下降板的动力特性。深震源地震的特征很好地解释了由相界扭曲引起的作用在板块上的俯冲力和浮力。同时指出，地震活动在700 km深度附近的突然消失可能是由于Pv和Mw组合的破裂引起的超塑性。对MgCO_3和MgCO_3- mgsio_3体系在25gpa和2000cc下进行的亚固态和熔融实验结果表明，在大于140 km的深度，CO_2不再以挥发组分的形式存在，而是以菱镁矿的形式固定存在，并通过火成岩过程逐渐释放到大气中。通过对高P、高T条件下CO_2在H_2O流体中的溶解度的考察，可以讨论考虑俯冲作用的CO_2再循环过程。大量的工作集中在下地幔物质的熔融关系上。MgSiO_3 Pv在2500℃/ 23 GPa下完全熔化，dTm/dP斜率约为25‰/GPa。MgO-FeO-SiO_2体系的熔炼过程在Pv和Mw之间呈现共晶熔炼。值得注意的是，共晶组分中SiO_2含量明显高于过渡带条件下的SiO_2含量，且随着深度的增加，共晶组分中SiO_2含量逐渐增加。将熔融实验扩展到芯材。结果表明，SiO_2组分在高于15 GPa的压力下溶于硅酸盐熔体中的铁液中，并且随着压力的增加，溶解作用增强。结果表明，作为核心热源的钾元素也会溶解在铁水中。这些结果使得建立一个地核形成模型成为可能，该模型可以一致地解释外核的轻元素，以及地核的演化和与地球冷却有关的D^1层的形成。少

The detailed phase diagrams of the olivine-modified spinel-spinel and the post spinel transformations, were constructed for the system Mg_2SiO_4-Fe_2SiO_4. The mantle spinel dissociates into perovskite (Pv) and magnesiowustite (Mw) within a depth interval less than 4 km making the 650 km discontinuity be sharp. This feature provide a fixed point of mantle temperature at 650 km depth and a standard temperature profile of the upper mantle was proposed. The dynamic nature of descending slabs was analyzed. The characteristics of deep focused earthquakes are well explained in terms of plunging and buoyant forces acting on the slabs caused by the distortions of phase boundaries. It was also pointed out that the sudden disappearance of seismic activity around 700 km depth would be due to the superplasticity associated with the breakdown assemblage of Pv and Mw.Results of subsolidus and melting experiments on MgCO_3 and the system MgCO_3-MgSiO_3 conducted up to 25 GPa and 2000 ﾟC revealed that … More , in the depths greater than 140 km, CO_2 no longer behaves as a volatile component but is fixed as magnesite, and that CO_2 is progressively released into the atmosphere by the igneous process. Examination of the solubility of CO_2 into H_2O fluid at high P and T made it possible to discuss the recycling process of CO_2 by taking the subduction into consideration.Extensive effort was focused on the melting relations of the lower mantle materials. MgSiO_3 Pv melts congruently at about 2500 ﾟC and 23 GPa with a dTm/dP slope of about 25ﾟ/GPa. The melting reration of the MgO-FeO-SiO_2 system exhibits a eutectic melting between Pv and Mw. It should be noteworthy that the eutectic composition is richer in SiO_2 than that found in the conditions of the transition zone and the composition is enriched in SiO_2 under further increase of depth. Melting experiments were extended to the core materials. It was demonstrated that SiO_2 component dissolves into molten iron from silicate melts at pressures higher than 15 GPa and the dissolution is enhanced by the increasing pressure. It was shown that potassium, a possible candidate as heat source in the core, also dissolves into molten iron. These results make it possible to construct a core formation model which consistently account for the light elements of the outer core, and the evolution of the core and the formation of the D^1 layer associated with cooling of the earth. Less