Equations of State, Elasticity, and Rheology of Earth Materials at High Pressures and Temperatures

高压和高温下地球材料的状态、弹性和流变方程

• 批准号: 0001173
• 负责人: Ho-kwang Mao
• 金额: $ 46.03万
• 依托单位: Carnegie Institution of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-08-01 至 2004-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0001173&HistoricalAwards=false
• 关键词: Equations; State; Elasticity; Rheology; Earth

Mao 0001173 A series of high-pressure experimental studies of the elasticity and equations of state of mantle and core materials needed to address major problems concerning the structure, dynamics, and evolution of the Earth's deep interior is proposed. The project takes advantage of numerous recent developments in diamond-anvil cell techniques, including cell design, high-temperature methods, synchrotron single-crystal and polycrystalline x-ray diffraction, synchrotron x-ray spectroscopy, and Brillouin scattering spectroscopy. The following experiments will be performed. (1) P-V-T equations of state of iron, iron alloys, and iron compounds will be studied to core pressures using polycrystalline x-ray diffraction with monochromatic x-radiation, hydrostatic pressure media, and an improved pressure calibration. (2) The shear modulus and elasticity tensor of core materials (initially e-Fe) will be determined up to 50 GPa and temperatures up to 1500 K using radial x-ray diffraction methods with monochromatic synchrotron radiation. (3) The technique will be further applied to study the rheological properties of these materials (including Fe, Fe-Ni, FeO, and FeS2) with accurate measurements of the intensities of reflections as a function of temperature and time. (4) The phonon densities of states of iron-bearing materials will be determined to core pressures using nuclear resonant inelastic x-ray scattering, as recently done for Fe to 153 GPa. Combined with theoretical calculations, the technique will be extended in later stages of the project to simultaneous high pressures and temperatures. (5) The P-V-T equations of state of principal deep mantle oxide and silicate phases will be determined using polycrystalline x-ray diffraction in hydrostatic media over the entire geotherm of the lower mantle. (6) This will be complemented by single-crystal x-ray diffraction of select phases for complete structure refinements to 100 GPa using a new combined energy dispersive/angle dispersive technique. (7) Brillouin scattering measurements of deep mantle phases [initially stishovite and (Mg,Fe)SiO3 perovskite] will be carried out to pressures above 50 GPa, and in the later stages of the project their temperature derivatives will be determined with resistive heating techniques. These results will provide an essential baseline for interpreting seismic velocity distributions and anisotropy of the lower mantle. (8) Finally, the calibration of pressure will be extended to high pressures and temperatures (800 K and 50 GPa) using the integrated Brillouin/x-ray diffraction approach recently applied to MgO at room temperature.

为了解决有关地球深部结构、动力学和演化的重大问题，需要对地幔和地核物质的弹性和状态方程进行一系列高压实验研究。该项目利用了金刚石压砧单元技术的许多最新发展，包括单元设计、高温方法、同步加速器单晶和多晶X射线衍射、同步加速器X射线光谱和布里渊散射光谱。将进行以下实验。(1)将利用多晶X射线衍射和单色X射线辐射、流体静压介质和改进的压力校准，研究铁、铁合金和铁化合物的P-V-T状态方程。(2)剪切模量和弹性张量的核心材料（最初的e-Fe）将确定高达50 GPa和温度高达1500 K使用径向X射线衍射方法与单色同步辐射。(3)该技术将进一步应用于研究这些材料（包括Fe，Fe-Ni，FeO和FeS 2）的流变性能，并精确测量反射强度随温度和时间的变化。(4)含铁材料的声子态密度将使用核共振非弹性X射线散射来确定核心压力，就像最近对Fe到153 GPa所做的那样。结合理论计算，该技术将在项目的后期阶段扩展到同时的高压和高温。(5)将在下地幔的整个地温范围内，利用流体静力学介质中的多晶X射线衍射，确定主要深部地幔氧化物和硅酸盐相的P-V-T状态方程。(6)这将通过选择相的单晶X射线衍射进行补充，以使用新的组合能量色散/角色散技术将完整的结构细化到100 GPa。(7)将在50 GPa以上的压力下对深地幔相[最初是斯铁云母和（Mg，Fe）SiO 3钙钛矿]进行布里渊散射测量，在项目的后期阶段，将用电阻加热技术确定它们的温度导数。这些结果将为解释下地幔的地震速度分布和各向异性提供必要的基线。(8)最后，校准的压力将被扩展到高压和高温（800 K和50 GPa）使用集成布里渊/X射线衍射方法最近适用于氧化镁在室温下。