Elasticity of Selected Deep Earth Phases Under Simultaneous High P-T Conditions Using Nuclear Resonant Inelastic X-ray Scattering

使用核共振非弹性 X 射线散射在同时高 P-T 条件下选定的深层地球相的弹性

• 批准号: 0711542
• 负责人: Jennifer Jackson
• 金额: $ 27.5万
• 依托单位: California Institute of Technology
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-08-01 至 2010-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0711542&HistoricalAwards=false
• 关键词: Elasticity; Selected; Deep; Earth; Phases

Recently observed seismic complexities require new and more accurate measurements of candidate lower mantle materials. The effort to understand the origin of these seismic complexities is an active area of modern cross-disciplinary research. Typically, models of the deep Earth have been made by extrapolating mineral properties to relevant pressure-temperature (P-T) conditions and comparing them with seismological determined compressional- and shear-wave velocities and density. However, the behavior of the shear properties of deep mantle materials is widely unknown. As a result, many extrapolations use either low P-T data, analogue materials, and/or infer that the chemically complex minerals behave the same as their end-member compositions. Even though ferropericlase (Mg,Fe)O and aluminous (Mg,Fe)SiO3 perovskite together make up more than 75% by volume of Earth's lower mantle, they are mostly optically opaque, making them difficult or impossible to study using optical scattering methods. In an effort to overcome these challenges, the use of established synchrotron methods of micro x-ray diffraction (Xrd) and nuclear resonant inelastic x-ray scattering (Nrixs) is engaged with diamond anvil cell and laser heating technology to obtain equations of state for chemically complex deep Earth materials under appropriate, yet uncharted, high-P-T conditions. With knowledge of the density determined from Xrd for these materials, the aggregate compressional and shear wave velocities, as well as the adiabatic bulk and shear moduli, is determined from the measured partial phonon density of states determined from Nrixs. These data permit the evaluation of the effects of iron and aluminum on the sound velocities and elasticity of deep Earth materials in a previously unexplored P-T sector. The results are expected to provide constraints on the correlation between seismological lateral variations and chemical composition.

最近观察到的地震复杂性需要对候选下层材料进行更新，更准确的测量。 了解这些地震复杂性的起源的努力是现代跨学科研究的活跃领域。 通常，通过将矿物质外推到相关压力温度（P-T）条件，并将其与地震学确定的压缩 - 压缩 - 波浪速度和密度进行比较，从而使深层的模型进行了。 然而，深地幔材料的剪切特性的行为尚不清楚。 结果，许多外推使用低P-T数据，模拟材料和/或推断化学复杂的矿物的行为与它们的最终成员组成相同。 即使纤维化酶（mg，fe）O和铝（mg，fe）sio3钙钛矿共同占地尺寸的低壁炉量超过75％，它们大多是光学上不透明的，使它们难以或不可能使用光学散射方法进行研究。为了克服这些挑战，使用已建立的微型X射线衍射（XRD）和核共振的非弹性X射线散射（NRIX）的使用同步加速器方法与钻石砧细胞和激光加热技术互动，以获得适用于适当的，未经教练的高-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T-P-T。 了解这些材料从XRD确定的密度的知识，骨料压缩和剪切波速度以及绝热的体积和剪切模量是由确定的Nrix确定状态的局部声子密度确定的。 这些数据允许评估铁和铝对先前未开发的P-T扇区中深层材料的声速和弹性的影响。 预计结果将对地震横向变异与化学组成之间的相关性产生限制。