Geophysics of Iron in the Earth's D" Layer and Core

地球？在地球内部的演化和动力学过程中，地核和核幔边界起着中心作用。地震观测提供了我们星球上这个最偏远地区的详细描述，但许多神秘的地震特征的解释等待深入了解铁和富铁化合物在极端压力-温度（P-T）条件下的矿物物理学，现场测量具有挑战性。该项目利用了高压同步加速器X射线技术的最新进展，推动了当前实验能力的极限，并集成了多个原位探测器，以测量地球周围的关键特性并解决基本的地球物理问题。s核和D？层.实验的重点是采取综合的方法来确定铁和富铁硅酸盐的高P-T弹性。对于铁，状态方程，总的压缩和剪切波速度，速度各向异性和晶格优选取向，和弹性张量将确定原位在金刚石砧室使用一套互补的同步X射线技术：流体静力学X射线衍射（XRD），径向XRD，核共振非弹性X射线散射，声子非弹性X射线散射。结果将解决主要问题，如内核地震各向异性，并将建立一个基准的纯铁约束的理论计算和比较与铁合金。对于核幔边界，本项目重点研究含铁硅酸盐后钙钛矿的弹性。 虽然硅酸盐PPV的发现在D？尽管硅酸盐后钙钛矿的性质在实验条件下是公认的，但由于实验挑战，关于硅酸盐后钙钛矿的性质的数据量一直很少。原位高P-T径向XRD测量将被应用到这一阶段，为了解地球的不寻常特征提供实验基础？s D？包括该层顶部的尖锐不连续性、速度横向变化、地震各向异性、VP-VS反相关和超低速带。

The Earth?s core and core-mantle boundary play a central role in the evolution and dynamic processes within the Earth. Seismological observations provide detailed descriptions of this most remote region in our planet, but interpretations of the many enigmatic seismic features await in-depth understanding of the mineral physics of iron and iron-rich compounds at extreme pressure-temperature (P-T) conditions where in-situ measurements are challenging. This project takes advantage of recent advances in high pressure synchrotron x-ray technology, pushes the envelope of current experimental capabilities, and integrates multiple in-situ probes in order to measure key properties and address fundamental geophysical questions surrounding the Earth?s core and D? layer. The experiments focus on taking an integrated approach in determining the high P-T elasticity of iron and iron-rich silicates. For iron, the equation of state, aggregate compressional and shear wave velocities, velocity anisotropy and lattice preferred orientation, and elastic tensor will be determined in-situ in a diamond anvil cell using a suite of complementary synchrotron x-ray techniques: hydrostatic x-ray diffraction (XRD), radial XRD, nuclear-resonant inelastic x-ray scattering, and phonon inelastic x-ray scattering. The results will address major issues such as inner core seismic anisotropy and will establish a benchmark for pure iron for constraint of theoretical calculations and comparison with iron alloys. For the core-mantle boundary, this project focuses on the elasticity of iron-bearing silicate post-perovskite. Although the significance of the discovery of silicate ppv at D? conditions is well recognized, due to experimental challenges, the amount of data on the properties of silicate post-pervoskite has been scarce. In-situ high P-T radial XRD measurements will be applied to this phase to provide the experimental foundation for understanding the unusual characteristics of the Earth?s D? layer, including the sharp discontinuity at the top of this layer, its lateral velocity variations, its seismic anisotropy, its VP-VS anti-correlation, and its ultralow-velocity zones.