High Pressure-Temperature Single-Crystal Elasticity of the Lower-Mantle Bridgmanite

下地幔布里奇曼石的高压-高温单晶弹性

• 批准号: 1916941
• 负责人: Jung-Fu Lin
• 金额: $ 41.53万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-06-01 至 2023-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1916941&HistoricalAwards=false
• 关键词: Pressure; Temperature; Single; Crystal; Elasticity

Earth's lower mantle extends from 670 km depth down to the core-mantle boundary, 2900 km deep. There, pressure and temperature exceed 1.3 million atm and 3500 K (5840 degree Fahrenheit). Understanding its properties is critical to constrain the planet dynamics. The lower mantle conducts heat away from the outer core. This contributes to power the Earth's magnetic field which shields us from the solar wind. Furthermore, thermal convection in the mantle drives plate tectonics and associated hazards, such as earthquakes and volcanic eruptions. Seismology, the study of seismic (elastic) waves, allows to observe directly the lower-mantle structures. But their interpretation requires knowledge of the elastic properties of the constitutive minerals. Bridgmanite accounts for more than 3/4th of the volume of the lower mantle, making it the most abundant mineral in the Earth. It is also of crucial interest when investigating lower-mantle properties. Here, the team quantifies experimentally the elastic properties of bridgmanite at the extreme conditions of the deep Earth. Coupling high pressure devices and state-of-the-art analytical techniques, they provide data allowing the interpretation of lower-mantle structures; notably that of large enigmatic provinces showing low seismic shear velocities. The project has strong implications in Seismology and broad impacts in Geodynamics. It also provides support and training in Mineral Physics for several graduate and undergraduate students, as well as educational outreach toward local elementary and middle schools. In this study, the team synthesize large single crystals of (Al,Fe)-bearing bridgmanite in the laboratory. Crystal properties are investigated at extreme conditions of pressure and temperature in the diamond-anvil cell. This apparatus generates high pressures at the tip of two opposing diamonds. The high temperatures are obtained by external heating or using focused laser beams. Crystal elastic properties are measured in situ using a combination of laboratory Brillouin and impulsive stimulated light scattering, as well as X-ray diffraction at national synchrotron facilities. This is achievable because the team is developing new technology in time-resolved impulsive laser spectroscopy. These new techniques will be shared with the community for future studies of material properties at extreme conditions. The researchers use the obtained data to constrain bridgmanite full elastic moduli as a function of pressure, temperature and of its contents in iron and aluminum. Extrapolation of the results to conditions relevant to the lower mantle, as well as modeling, allows interpreting seismological observations. The project outcomes further the understanding of seismic velocities, temperature profiles and chemical compositions in the deep Earth.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

地球的下层从670公里的深度向下延伸至核心壳边界，深度为2900公里。在那里，压力和温度超过130万ATM和3500 K（华氏5840度）。了解其特性对于限制行星动态至关重要。下幔将热量从外部核心转移。这有助于为地球的磁场提供动力，从而使我们免受太阳风的影响。此外，地幔中的热对流驱动板块构造和相关的危害，例如地震和火山喷发。地震学（弹性）波的研究允许直接观察到较低的牢房结构。但是他们的解释需要了解构成矿物的弹性特性。 Bridgmanite占低地幔体积的3/4以上，使其成为地球上最丰富的矿物。研究较低的壳体性质时，它也具有至关重要的兴趣。在这里，团队通过实验量化了Bridgmanite在深地球极端条件下的弹性特性。将高压设备和最先进的分析技术耦合，它们提供了允许解释较低壳结构的数据；值得注意的是，大型神秘省份显示出低地震剪切速度。该项目对地震学和地球动力学的广泛影响具有很大的影响。它还为几位研究生和本科生提供矿物质物理学的支持和培训，以及对当地中小学的教育宣传。在这项研究中，团队合成了实验室中的（Al，Fe）的大晶体。在钻石 - 洋维区细胞中的压力和温度的极端条件下研究了晶体性能。该设备在两只相对的钻石的尖端产生了很高的压力。高温是通过外部加热或使用聚焦激光束获得的。使用实验室布里渊和冲动刺激的光散射以及国家同步器设施的X射线衍射，原位测量晶体弹性特性。这是可以实现的，因为该团队正在使用时间分辨的冲动激光光谱开发新技术。这些新技术将与社区共享，以在极端条件下对物质特性进行未来的研究。研究人员使用获得的数据来限制Bridgmanite全弹性模量，这是铁和铝中其压力，温度及其含量的函数。将结果推断到与下地幔相关的条件以及建模，允许解释地震学观察。该项目的结果进一步理解了深层地球上的地震速度，温度曲线和化学成分。该奖项反映了NSF的法定任务，并且使用基金会的智力优点和更广泛的影响评估标准，认为值得通过评估来获得支持。

项目成果

Nonlinear effects of hydration on high-pressure sound velocities of rhyolitic glasses

水合作用对流纹岩玻璃高压声速的非线性影响

• DOI: 10.2138/am-2021-7597
• 发表时间: 2021
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Gu, Jesse T.;Fu, Suyu;Gardner, James E.;Yamashita, Shigeru;Okuchi, Takuo;Lin, Jung-Fu
• 通讯作者: Lin, Jung-Fu

Atomistic insight into the ferroelastic post-stishovite transition by high-pressure single-crystal X-ray diffraction

• DOI: 10.2138/am-2022-8458
• 发表时间: 2022-07
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Yanyao Zhang;S. Chariton;Jiaming He;S. Fu;Fang Xu;V. Prakapenka;Jung‐Fu Lin