Nature of a Low Velocity Anomaly in the Mantle Transition Zone Beneath the Western Great Plains

西部大平原地幔过渡带低速异常的性质

• 批准号: 2149587
• 负责人: Kelly Liu
• 金额: $ 18.91万
• 依托单位: Missouri University of Science and Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-01-01 至 2024-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2149587&HistoricalAwards=false
• 关键词: Nature; Low; Velocity; Anomaly; Mantle

Decades of intensive research in the geological sciences have convincingly shown that large-scale surface features such as mountain belts, ocean basins, and rifted valleys; and natural hazards such as earthquakes and volcanic eruptions; are manifestations of dynamic processes occurring in the deep interior of the Earth. One of these processes is the upwelling of hotter-than-normal, partially melted rocks in the Earth’s mantle. In recent years, a number of geophysical studies have identified such upwelling beneath the western Great Plains, but the geometry, depth extent, and more importantly, formation mechanism for this feature remain enigmatic. This study will employ a suite of computationally-intensive geophysical techniques to investigate this intriguing feature. Findings from this study will shed light on similar features elsewhere on Earth, ultimately improving our capability to understand, predict, and mitigate natural hazards and effectively explore and develop natural resources. The proposed scientific investigations will have significant impacts for geoscientists from a wide range of fields and career stages. A graduate student, two undergraduate students, and a summer intern will be involved in the study. Materials developed from this project will be integrated into various educational programs at the university aimed at recruiting minority undergraduate and graduate students into scientific careers.The research team will use an array of seismologic approaches to investigate the existence and nature of a prominent low velocity anomaly beneath the western Great Plains by testing three hypotheses, including whether it represents 1) an anomalously hot, low-density, upwelling feature associated with the subduction of the Farallon slab; 2) an emerging plume originating from the lower mantle; and 3) a zone of high water content in the mantle transition zone. Research tasks to test the hypotheses include velocity corrections to the apparent transition zone discontinuity depths, obtained using P-to-S receiver functions; imaging the mantle transition zone using multiply reflected P-to-S conversions; investigation of seismic anisotropy layering; and constraining the anomaly feature using synthetic tests. Testing these hypotheses may provide first-order constraints for geodynamic models, leading to significant progress in understanding the tectonic evolution of North America.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.

数十年的地质科学研究令人信服地表明，大范围的地表特征，如山带、海洋盆地和裂谷，以及自然灾害，如地震和火山爆发，都是发生在深层内部的动力过程的表现。这些过程之一是地幔中比正常情况更热、部分熔化的岩石的上升流。近年来，许多地球物理研究已经发现了地下​​的这种上升流。西部大平原，但该特征的几何形状、深度范围，更重要的是，其形成机制仍然是个谜。这项研究将采用一套计算密集型地球物理技术来研究这一有趣的特征。地球其他地方的类似特征，最终提高我们理解、预测和减轻自然灾害以及有效探索和开发自然资源的能力，拟议的科学研究将对各个领域和职业阶段的地球科学家产生重大影响。 ，两名本科生，一名暑期实习生将参与这项研究。该项目开发的材料将被纳入大学的各种教育计划中，旨在招募少数民族本科生和研究生从事科学职业。研究小组将使用一系列地震学方法来调查地震的存在。通过测试三个假设，包括它是否代表 1) 与法拉隆板片俯冲相关的异常炎热、低密度、上升流特征 2) 新兴的羽流，来研究西部大平原下方显着的低速异常的性质；源自下地幔；3) 地幔过渡带的高含水量区域，用于检验假设的研究任务包括使用 P-to-S 接收器函数对明显的过渡带不连续深度进行速度校正；使用反射多重 P 到 S 转换来研究地幔过渡带；研究地震各向异性分层；并使用综合测试来检验这些假设可以为地球动力学模型提供一阶约束，从而在地质动力学方面取得重大进展。了解北美的构造演化。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

Seismic Azimuthal Anisotropy Beneath a Fast Moving Ancient Continent: Constraints From Shear Wave Splitting Analysis in Australia

• DOI: 10.1029/2022jb025866
• 发表时间: 2023-01
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Kailun Ba;Stephen S. Gao;Jian-Li Song;Kelly H. Liu

Metastable olivine within oceanic lithosphere in the uppermost lower mantle beneath the eastern United States

• DOI: 10.1130/g49879.1
• 发表时间: 2022-04
• 期刊: Geology
• 影响因子: 5.8
• 作者: F. Kong;Stephen S. Gao;Kelly H. Liu;Yinxia Fang;Hejun Zhu;R. Stern;Jiabiao Li

A possible lithospheric drip underneath the East Sayan Mountains in central Asia

中亚东萨彦山脉下方可能存在岩石圈滴水

• 发表时间: 2022
• 期刊: American Geophysical Union Fall Meeting
• 作者: Liao, Y.;Gao, S.S.
• 通讯作者: Gao, S.S.