Chemistry of the Earth's Deep Mantle and Core

摘要：Hemley和Mao，华盛顿卡内基研究所，地球物理实验室该项目的目标是确定下地幔和地核物质在相关地球深部条件下的化学性质，以便获得对行星内部化学组成、形成和演化的直接实验约束。这项研究利用了许多新的发展，原位高压技术，包括同步加速器X射线衍射和光谱学，红外和光学技术，中子衍射，和新的高金刚石细胞的方法。该项目将首先改进深部地幔和核心条件下的压力和温度校准。有了这种提高的精度，将进行原位X射线衍射研究，以解决当前关于后尖晶石相边界作为压力-温度和组成（P-T-X）的函数的问题。含铁和铝的镁硅酸盐钙钛矿的缺陷结构和浓度将通过详细的成分研究和中子粉末衍射直接占位测量来表征。一系列互补的同步加速器X射线光谱技术，用于表征下地幔P-T范围内这些相态中铁的自旋和氧化态。额外的问题，非常高的P-T相的Fe和Fe-Ni合金将使用金刚石垫片双面激光加热/同步X射线衍射技术进行研究。高分辨率的X射线发射，核共振前向散射，和光学拉曼光谱将被用来确定可能的压力引起的变化，在电子，磁性和振动特性的铁合金的核心压力。在较低的压力范围内的高P-T X射线衍射测量也将允许调查的结构变化的液态铁。核心中轻元素的问题将在几个铁镍伪二元系统中进行研究，从氧开始，然后使用相同的衍射和光谱技术转移到硫和氢。

AbstractEAR-0126009Hemley and MaoCarnegie Institution of Washington, Geophysical LaboratoryThe goal of this project is to determine the chemical properties of lower mantle and core materials at relevant deep Earth conditions in order to obtain direct experimental constraints on the chemical composition, formation, and evolution of the planet's interior. The research takes advantage of numerous new developments in situ high-pressure techniques, including synchrotron x-ray diffraction and spectroscopy, infrared and optical techniques, neutron diffraction, and new high diamond-cell methods. The project will start by improving both pressure and temperature calibration at deep mantle and core conditions. With this improved accuracy, in-situ x-ray diffraction studies will be performed to resolve current questions about the post-spinel phase boundary as a function of pressure-temperature and composition (P-T-X). The defect structure and concentration of iron and aluminum-bearing magnesium silicate perovskites will be characterized by detailed compositional studies and by direct site-occupancy measurements with neutron powder diffraction. A series of complementary synchrotron x-ray spectroscopic techniques used to characterize the spin and oxidation state of iron in these phases throughout the P-T range of the lower mantle. The question of additional, very high P-T phases of Fe and Fe-Ni alloys will be investigated using diamond gasket double-sided laser heating/synchrotron x-ray diffraction techniques. High-resolution x-ray emission, nuclear resonant forward scattering, and optical Raman spectroscopies will be used to identify possible pressure-induced changes in electronic, magnetic, and vibrational properties of iron alloys to core pressures. High P-T x-ray diffraction measurements in the lower pressure range will also allow investigations of structural changes in the liquid state of Fe. The problem of the light element in the core will be examined in a few pseudo-binary systems with Fe-Ni, starting with oxygen and then moving to sulfur and hydrogen using the same battery of diffraction and spectroscopic techniques.