EAR-PF:Quantifying Scale of Lower Crust and Mantle Heterogeneities Beneath the Continental United States: Bridging Seismology, Mineral Physics, Petrology, and Magnetotellurics

EAR-PF：美国大陆下方地壳和地幔异质性的量化尺度：连接地震学、矿物物理学、岩石学和大地电磁学

• 批准号: 1952642
• 负责人: William Shinevar
• 金额: $ 17.4万
• 依托单位: Shinevar, William J
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-02-01 至 2023-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1952642&HistoricalAwards=false
• 关键词: EAR; PF; Quantifying; Scale; Lower

Dr. William Shinevar has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education activities at University of Colorado Boulder under the mentorship of Dr. Vera Schulte-Pelkum. The goal of this project is to improve interpretations of lower crustal and mantle seismic anomalies in terms of temperature, pressure, major element chemistry, hydration, and melt fraction by integrating constraints from the measurement of Earth’s electrical resistivity (magnetotellurics), and the directional dependence of the seismic wavespeeds (seismic anisotropy). Constraining the scale of lower crustal and mantle thermal and chemical heterogeneities is fundamental to determining the rheology and stress state of the lithosphere. This, in turn, is crucial to understanding seismic hazard, as well as how the continental crust and mantle compositionally evolved over Earth’s history, which is important to better understand the formation of natural resources. Dr. Shinevar’s education plan focuses on mentoring an undergraduate student on a research project associated in order to introduce a student to interdisciplinary approaches for understanding Earth processes. In addition, he will participate in public outreach and K-12 education activities in the Boulder area.Seismic wave speed on the lithospheric-scale is dependent on the (an)elastic moduli of the minerals present as well as the distribution and elastic moduli of fluids if present. The minerals present mainly depend on major element composition, water content, pressure, and temperature. Seismic wavespeeds of lower crustal and mantle rocks have been recently calculated using databases of whole-rock compositions, thermodynamic modelling, and grain-scale experimental observations of mineral moduli and anelasticity. The interpretation of seismic wavespeeds is non-unique. Applying these new calculations, this project will assess the scale and magnitude of chemical and thermal heterogeneities compatible with the most current seismic tomographic models of the lower crust and upper mantle, thus quantifying interpretation uncertainty. However, not all wavespeeds from these tomographic models can be interpreted using these calculations. For these anomalous regions, two other datasets will be used: seismic anisotropy can estimate uncertainty in isotropic tomographic models, and magnetotelluric measurements, which are highly sensitive to fluids and silicate melts, can better constrain mantle melt fraction or hydration. With these independent constraints, tomographic models will be edited to include expected seismic wavespeeds in anomalous regions due to melt or hydrous phases. Seismic delay times will be forward modeled to validate these calculations. This synthesis will increase our understanding of the evolution of mantle lithosphere from the Archean to the present as well as allow for a direct link between large-scale geophysical observations and small-scale laboratory measurements.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.

William Shinevar博士在Vera Schulte-Pelkum博士的心态下获得了NSF耳朵的博士后奖学金，以在科罗拉多大学博尔德大学进行研究和教育活动。该项目的目的是通过整合地球电阻率（磁性磁磁性）的限制来改善温度，压力，主要元素化学，水合和熔体分数的较低地壳和地震地震异常的解释。限制下地壳和地幔热和化学异质性的规模对于确定岩石圈的流变和应力状态至关重要。反过来，这对于了解地震危险以及大陆地壳和地幔如何在地球历史上演变而成，这对于更好地理解自然资源的形成非常重要。 Shinevar博士的教育计划着重于指导一名本科生对相关的研究项目的指导，以便将学生介绍到了解地球过程的跨学科方法。此外，他还将参加巨石区域的公共外展和K-12教育活动。岩石圈规模上的视力波速度取决于存在的矿物质的（AN）弹性模量以及流体的分布和弹性模量（如果存在）。存在的矿物主要取决于主要元素成分，水含量，压力和温度。最近，使用全岩体组成，热力学建模以及矿物模量和厌氧性的晶尺度实验观测来计算下地壳和地幔岩石的地震波动。地震波的解释不是唯一的。应用这些新计算，该项目将评估与下地壳和上地幔的最新地震层析成像模型兼容的化学和热异质性的规模和幅度，从而量化了解释不确定性。但是，并非可以使用这些计算来解释这些断层扫描模型的所有波动。对于这些异常区域，将使用另外两个数据集：地震各向异性可以估计各向同性层析成像模型中的不确定性，而磁性纤维化测量值对流体和硅胶融化高度敏感，可以更好地限制地幔分数或水合。借助这些独立的约束，将编辑层析成像模型，以包括由于熔体或含水相，在异常区域中包括预期的地震波。地震延迟时间将被转发建模以验证这些计算。这种综合将增加我们对地幔岩石圈从大天老到现在的发展的理解，并允许在大规模的地球物理观察和小规模的实验室测量之间直接联系。该奖项反映了NSF的法定任务，并通过使用基金会的知识优点和广泛的范围来评估，通过评估来获得珍贵的支持。

项目成果

Mantle thermochemical variations beneath the continental United States through petrologic interpretation of seismic tomography

通过地震层析成像的岩石学解释美国大陆下方的地幔热化学变化

• 发表时间: 2023
• 期刊: Earth and planetary science letters
• 影响因子: 5.3
• 作者: Shinevar, William J.;Golos, Eva M.;Jagoutz, Oliver;Behn, Mark D.;Van der Hilst, Robert D.
• 通讯作者: Van der Hilst, Robert D.

Geophysical‐Geochemical Modeling of Deep Crustal Compositions: Examples of Continental Crust in Typical Tectonic Settings and North China Craton

• DOI: 10.1029/2022jb025536
• 发表时间: 2023-05
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: D. Cui;Jing‐Liang Guo;William J. Shinevar;Liang Guo;Wangchun Xu;Hongfei Zhang;Zhenyi Jin