EAR-PF: Water in the Lower Mantle: Gaining Insight through Melt Generation and Deformation Textures

EAR-PF：下地幔中的水：通过熔化生成和变形纹理获得洞察

• 批准号: 1855336
• 负责人: Cara Vennari
• 金额: $ 17.4万
• 依托单位: Vennari, Cara Elizabeth
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-01 至 2021-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1855336&HistoricalAwards=false
• 关键词: EAR; PF; Water; Lower; Mantle

Dr. Cara Vennari has been granted an NSF EAR postdoctoral fellowship to carry out research and education plans at the University of Chicago and the University of Utah. Water has been studied extensively in the upper mantle, where it has been shown to lower the melting temperature of mantle rock and weaken it; however, there has been less systematic study of water in the lower mantle. Using diamond anvil cells to generate high pressures during laboratory experiments, she will investigate the melting temperature and strength of lower mantle rock with a variety of water content to advance our understanding of hydrous silicate melts and explain local anisotropic regions of the lower mantle. Broader impacts of this work include its direct application to other Earth science disciplines (geodynamics, petrology, geophysics, planetary sciences and geochemistry), mentorship of younger students, and volunteering through outreach programs. The overall goal of this project is to understand the effect of water in the lower mantle. The first is high pressure melting of synthetic pyrolite composition, with the goals being to determine (with a range of water content) the melting temperature, explore the stable phases, and probe the melt and recrystallized products for the cation and hydrous distribution. Hydrous melts and mineralogy have been assumed to affect the rheologic character of the lower mantle properties; however, there have been no experimental evidence to support this, so the second type of experiment will be an axial stress experiment at lower mantle pressures to investigate the deformation of hydrous peridotite. Techniques used for the melting measurements include in situ powder diffraction coupled with ex situ SEM analysis. Strength measurements of hydrated lower mantle phases will be investigated using X-ray diffraction with radial geometry.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.

Cara Vennari 博士已获得 NSF EAR 博士后奖学金，在芝加哥大学和犹他大学开展研究和教育计划。人们对上地幔中的水进行了广泛的研究，结果表明水可以降低地幔岩石的熔化温度并削弱其强度。然而，对下地幔中的水的系统研究还较少。她将在实验室实验中利用金刚石砧细胞产生高压，研究具有各种含水量的下地幔岩石的熔化温度和强度，以增进我们对含水硅酸盐熔体的理解并解释下地幔的局部各向异性区域。这项工作的更广泛影响包括其直接应用于其他地球科学学科（地球动力学、岩石学、地球物理学、行星科学和地球化学）、对年轻学生的指导以及通过外展计划进行志愿服务。该项目的总体目标是了解水对下地幔的影响。第一个是合成硫磺铁矿组合物的高压熔化，目标是确定（在一定水含量范围内）熔化温度，探索稳定相，并探测熔化物和重结晶产物的阳离子和水合分布。含水熔体和矿物学被认为会影响下地幔性质的流变特征；然而，还没有实验证据支持这一点，因此第二类实验将是较低地幔压力下的轴向应力实验，以研究含水橄榄岩的变形。用于熔化测量的技术包括原位粉末衍射与异位 SEM 分析相结合。将使用 X 射线衍射和径向几何来研究水合下地幔相的强度测量。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

A high-pressure Raman study of FeTiO3 ilmenite: Fermi resonance as a manifestation of Fe-Ti charge transfer

FeTiO3 钛铁矿的高压拉曼研究：费米共振作为 Fe-Ti 电荷转移的表现

• DOI: 10.1007/s00269-021-01151-9
• 发表时间: 2021
• 期刊: Physics and Chemistry of Minerals
• 影响因子: 1.4
• 作者: Vennari, Cara E.;Williams, Quentin
• 通讯作者: Williams, Quentin

Deformation and Strength of Mantle Relevant Garnets: Implications for the Subduction of Basaltic-rich Crust

与地幔相关的石榴石的变形和强度：对富含玄武质地壳俯冲的影响

• DOI: 10.2138/am-2021-7587
• 发表时间: 2021
• 期刊: American Mineralogist
• 影响因子: 3.1
• 作者: Vennari, C;Lin, F;Kunz, M;Akaogi, M;Miyagi, L;Williams, Q
• 通讯作者: Williams, Q