Elasticity of clinopyroxene (Ca, Na) (Mg, Al, Fe) Si2O6 under Earth's upper mantle conditions

地球上地幔条件下单斜辉石(Ca,Na)(Mg,Al,Fe)Si2O6的弹性

• 批准号: 1646527
• 负责人: Jin Zhang
• 金额: $ 33.86万
• 依托单位: University of New Mexico
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-15 至 2022-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1646527&HistoricalAwards=false
• 关键词: Elasticity; clinopyroxene; Ca; Na; Mg

The Earth's upper mantle is one of the most dynamic layers of our planet and closely related to many tectonic processes adversely affecting human beings. For example, subduction and delamination, which are the two major geological processes of recycling crustal materials into the deep Earth, can result in seismic heterogeneities and anisotropies in the Earth's interior, as well as destructive Earthquakes and volcanisms on the Earth's surface. Therefore, understanding the nature and dynamics of the Earth's upper mantle is not only crucial for studying the mantle composition and convection but also relevant to society. Due to the difficulties of direct sampling, seismology provides by far the most accurate image of the Earth's upper mantle. Sound velocity and density measurements of relevant minerals are essential for understanding upper mantle seismic observations. Clinopyroxene, as a major phase of the Earth's upper mantle (10-30 vol%) and the dominating mineral of eclogite (about 60-70 vol%), is one of the most important yet least studied groups of minerals of the Earth's interior. Eclogite is widely believed to be the main driving force for subduction and delamination because of its high density. Thus direct density measurements of clinopyroxene at high pressure (P)-temperature (T) conditions are needed for calculating the buoyancy of eclogite in the Earth's interior. In addition, clinopyroxene is the most anisotropic major mineral in the Earth's upper mantle. It is also the only phase that contributes to any observed anisotropy of eclogite. Explanation of seismically observed upper mantle anisotropy requires knowledge of single-crystal elasticity of clinopyroxene at real Earth P-T conditions. Previous experimental studies have been limited mainly to high-symmetry materials, such as garnet, under P-T conditions far less than those expected in the Earth's interior. The purpose of this study is to measure the density and single-crystal elasticity of clinopyroxene in-situ, implement the optical system that is needed to complete the proposed experiments at University of New Mexico, apply the obtained experimental results to real Earth, and create unique opportunities for graduate and undergraduate students, especially underrepresented minority students, to participate in scientific research at the state-of-the-art experimental facilities both on campus and at national laboratories.The investigators will use synchrotron single-crystal micro-diffraction and single-crystal Brillouin spectroscopy combined with CO2 laser heating or resistive heating methods to systematically investigate the thermoelastic properties (including density and single-crystal elasticity) of clinopyroxene with different chemical compositions up to 1800K and 18 GPa, covering the entire stability field in the Earth's upper mantle. The obtained experimental result will be used to assist seismic interpretation and geodynamical modeling, which will eventually contribute to our understanding of the origin and nature of the anisotropy and heterogeneity observed in the Earth's upper mantle.

地球上地幔是地球上最活跃的层之一，与许多对人类产生不利影响的构造过程密切相关。例如，俯冲和分层，这是地壳物质再循环到地球深部的两个主要地质过程，可以导致地球内部的地震不均匀性和各向异性，以及地球表面的破坏性地震和火山活动。因此，了解地球上地幔的性质和动力学不仅对研究地幔成分和对流至关重要，而且与社会有关。由于直接采样的困难，地震学提供了迄今为止地球上地幔最准确的图像。有关矿物的声速和密度测量对于了解上地幔地震观测是必不可少的。单斜辉石作为地球上地幔的主要相态（10-30 vol%）和榴辉岩的主要矿物（约60-70 vol%），是地球内部最重要但研究最少的矿物之一。由于地壳的高密度，人们普遍认为地壳是俯冲和拆沉的主要驱动力。因此，为了计算榴辉岩在地球内部的浮力，需要在高压（P）-高温（T）条件下直接测量单斜辉石的密度。此外，单斜辉石是地球上地幔中各向异性最强的主要矿物。这也是唯一的阶段，有助于任何观察到的各向异性的榴辉岩。解释地震观测到的上地幔各向异性需要了解单斜辉石在真实的地球P-T条件下的单晶弹性。以前的实验研究主要局限于高对称性材料，如石榴石，其P-T条件远低于地球内部的预期。本研究的目的是原位测量单斜辉石的密度和单晶弹性，实现在新墨西哥州大学完成拟议实验所需的光学系统，将获得的实验结果应用于真实的地球，并为研究生和本科生，特别是代表性不足的少数民族学生，参与科学研究的国家最先进的实验设施都在校园和国家实验室。调查人员将使用同步加速器单晶微衍射和单晶，晶体布里渊光谱结合CO2激光加热或电阻加热方法，系统地研究热弹性性质（包括密度和单晶弹性），覆盖了地球上地幔的整个稳定场。所获得的实验结果将被用于辅助地震解释和地球动力学建模，这将最终有助于我们理解在地球上地幔中观察到的各向异性和非均匀性的起源和性质。

项目成果

The seismically fastest chemical heterogeneity in the Earth's deep upper mantle—implications from the single-crystal thermoelastic properties of jadeite

• DOI: 10.1016/j.epsl.2020.116345
• 发表时间: 2020-08
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: M. Hao;Jin S. Zhang;C. Pierotti;Wencai Zhou;Dongzhou Zhang;P. Dera

The single-crystal elastic properties of the jadeite-diopside solid solution and their implications for the composition-dependent seismic properties of eclogite

硬玉-透辉石固溶体的单晶弹性特性及其对榴辉岩成分相关地震特性的影响

• DOI: 10.2138/am-2019-6990
• 发表时间: 2019
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Hao, Ming;Pierotti, Caroline E.;Tkachev, Sergey;Prakapenka, Vitali;Zhang, Jin S.
• 通讯作者: Zhang, Jin S.

The Water-Fe-Pressure dependent single-crystal elastic properties of wadsleyite: Implications for the seismic anisotropy in the upper Mantle Transition Zone

瓦兹利石的水-铁-压力依赖性单晶弹性特性：对上地幔过渡带地震各向异性的影响

• DOI: 10.1016/j.epsl.2021.116955
• 发表时间: 2021
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Zhou, Wen-Yi;Ren, Zhiyuan;Zhang, Jin S.;Chen, Bin;Hao, Ming;Ohuchi, Tomohiro;Miyagi, Lowell;Zhang, Dongzhou;Alp, Esen E.;Lavina, Barbara
• 通讯作者: Lavina, Barbara

High‐Pressure Single‐Crystal Elasticity and Thermal Equation of State of Omphacite and Their Implications for the Seismic Properties of Eclogite in the Earth's Interior

• DOI: 10.1029/2018jb016964
• 发表时间: 2019-03
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: M. Hao;Jin S. Zhang;C. Pierotti;Z. Ren;D. Zhang

High pressure-temperature single-crystal elasticity of ringwoodite: Implications for detecting the 520 discontinuity and metastable ringwoodite at depths greater than 660 km

• DOI: 10.1016/j.epsl.2021.117359
• 发表时间: 2022-02
• 期刊: Earth and Planetary Science Letters
• 影响因子: 5.3
• 作者: Wencai Zhou;Jin S. Zhang;Quancheng Huang;X. Lai;Bin Chen;P. Dera;B. Schmandt