CSEDI: Understanding the influence of mantle dynamics on the generation of Earth's magnetic field throughout the plate tectonics cycle.

CSEDI：了解整个板块构造周期中地幔动力学对地球磁场产生的影响。

• 批准号: 2054605
• 负责人: Courtney Sprain
• 金额: $ 42.87万
• 依托单位: University of Florida
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-15 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2054605&HistoricalAwards=false
• 关键词: CSEDI; Understanding; influence; mantle; dynamics

Earth's magnetic field acts as a shield against cosmic radiation and magnetic storms, which can potentially damage technical infrastructure, harm life, and strip away Earth's atmosphere. Understanding the evolution of the magnetic field therefore has important implications for Earth's habitability today and throughout history. An outstanding question that currently limits understanding of the evolution the magnetic field is: When did the solid inner core form? Today, the solidification of the inner core is an important driver of the geodynamo, which generates Earth’s magnetic field. This project seeks to better constrain the timing of inner core formation, which will be accomplished by a unique coupling of mantle convection models to geodynamo simulations that produce Earth-like magnetic fields. The results from this project will have a scientific impact in multiple disciplines, including geodynamics, magnetospheric physics, studies of the deep interior, and the evolution of life. More generally, this project addresses the important question of “How is Earth’s internal field generated?”, which can help to better predict future magnetic field changes that could result in harm to modern technical infrastructure or life itself. Additionally, the proposed work will support two early-career female PIs, build STEM talent by training and educating two undergraduate students and one postdoctoral researcher, improve available scientific infrastructure by releasing the created software as open-source, and will facilitate international exchange with project collaborators in the UK and France. A wide audience will be engaged through a multi-year outreach initiative building on the successful Scientist in Every Florida School program in collaboration with University of Florida Thompson Earth Systems Institute.Because the growth of the inner core is a major driver of the geodynamo today, it can be assumed that inner core nucleation may have caused significant changes in Earth's past magnetic field. But so far, the interpretation of any detectable signal in the paleomagnetic data at the Earth’s surface has remained ambiguous because (1) the precise effects of inner core nucleation on the magnetic field are unknown, and (2) the magnitude of magnetic field variations caused by mantle convection are currently not well constrained. This project will quantify the largest possible influence of mantle heat transport on the magnetic field at Earth’s surface, taking into account the influence of inner core size. This will be accomplished by computing realistic core-mantle boundary heat flux patterns generated by mantle convection models, and coupling them to geodynamo simulations that produce Earth-like magnetic fields as assessed with the Quality of Paleomagnetic Modeling (QPM) criteria, which is currently the only criteria set that assesses if simulations are reproducing Earth’s long-term magnetic field behavior. In contrast to previous studies, these mantle models do not try to recreate the relatively limited timeframe of known plate motions, or apply simplified heat flux patterns for present-day conditions, but instead predict the largest realistic heat flux variations caused by synthetic plate configurations during the cycle of supercontinent formation and dispersal in Earth's past. This work will improve understanding of the mantle’s role in regulating the magnetic field throughout Earth's history. Additionally, this work will determine whether changes in the magnetic field so far ascribed to inner core nucleation could instead partly or completely be explained by mantle dynamics alone. This project connects planetary evolution, mantle convection, the geodynamo, and paleomagnetic data. This wide collaboration will drive significant advances in the understanding of the Earth as one system, not separated into its layers. More generally, this project addresses the science priority question, “How is Earth’s internal field generated?”, released in the National Academies of Science, Engineering and Medicine decadal report for NSF-EAR.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.

地球磁场起到了抵御宇宙辐射和磁暴的作用，宇宙辐射和磁暴可能会破坏技术基础设施，损害生命，并剥离地球大气层。因此，了解磁场的演变对今天和整个历史上地球的宜居性具有重要的意义。目前限制对磁场演化理解的一个悬而未决的问题是：固体内核是什么时候形成的？今天，内核的凝固是产生地球磁场的地球发电机的重要驱动力。该项目寻求更好地限制内核形成的时间，这将通过地幔对流模型与产生类似地球磁场的地球发电机模拟的独特耦合来实现。该项目的结果将对多个学科产生科学影响，包括地球动力学、磁层物理学、深部内部研究和生命进化。更广泛地说，这个项目解决了“地球内部磁场是如何产生的？”这一重要问题，这有助于更好地预测未来的磁场变化，这些变化可能会对现代技术基础设施或生命本身造成损害。此外，拟议的工作将支持两名职业生涯早期的女性个人投资主管，通过培训和教育两名本科生和一名博士后研究员来培养STEM人才，通过将创建的软件作为开源发布来改善现有的科学基础设施，并将促进与英国和法国的项目合作者的国际交流。通过与佛罗里达大学汤普森地球系统研究所合作，在成功的每一所佛罗里达学校的科学家计划的基础上，将有更多的受众参与其中。由于内核的增长是当今地球发电机的主要驱动力，可以假设内核的成核可能已经导致地球过去的磁场发生重大变化。但到目前为止，对地球表面古地磁数据中任何可探测到的信号的解释仍然含糊不清，因为(1)内核成核对磁场的精确影响尚不清楚，(2)地幔对流引起的磁场变化的幅度目前还没有得到很好的约束。该项目将量化地幔热传输对地球表面磁场的最大可能影响，并考虑到内核大小的影响。这将通过计算地幔对流模型产生的真实的核-地幔边界热通量模式，并将其与产生类似地球的磁场的地球发电机模拟相耦合来实现，该模拟产生了用古地磁模拟质量(QPM)标准评估的类似地球的磁场，这是目前评估模拟是否再现地球长期磁场行为的唯一标准集。与以前的研究不同，这些地幔模型没有试图重现已知板块运动的相对有限的时间框架，也没有针对当今条件应用简化的热通量模式，而是预测了过去地球超大陆形成和扩散周期中由合成板块构型引起的最大实际热通量变化。这项工作将提高对地幔在地球历史上调节磁场的作用的理解。此外，这项工作将确定迄今为止归因于内核成核的磁场变化是否可以部分或完全由地幔动力学来解释。该项目连接了行星演化、地幔对流、地球发电机和古地磁数据。这种广泛的合作将推动对地球作为一个系统而不是分成不同层次的理解的重大进展。更广泛地说，这个项目解决了NSF-EAR在国家科学院、工程院和医学院发布的十年报告中发布的科学优先问题：地球内部场是如何产生的。这个奖项反映了NSF的法定使命，并通过使用基金会的智力优势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

The role of subduction in the formation of Pangean oceanic large igneous provinces

俯冲在泛古大陆大洋火成岩省形成中的作用

• DOI: 10.1144/sp542-2023-12
• 发表时间: 2023
• 期刊: Special Publications
• 作者: Heron, Philip J.;Gün, Erkan;Shephard, Grace E.;Dannberg, Juliane;Gassmöller, Rene;Martin, Erin;Sharif, Aisha;Pysklywec, Russell N.;Nance, R. Damian;Murphy, J. Brendan
• 通讯作者: Murphy, J. Brendan

How lowermost mantle viscosity controls the chemical structure of Earth’s deep interior

• DOI: 10.1038/s43247-023-01153-1
• 发表时间: 2023-12
• 期刊: Communications Earth & Environment
• 作者: J. Dannberg;K. Chotalia;Rene Gassmöller

An entropy method for geodynamic modelling of phase transitions: capturing sharp and broad transitions in a multiphase assemblage

用于相变地球动力学建模的熵方法：捕获多相组合中的急剧和广泛的转变

• DOI: 10.1093/gji/ggac293
• 发表时间: 2022
• 期刊: Geophysical Journal International
• 影响因子: 2.8
• 作者: Dannberg, Juliane;Gassmöller, Rene;Li, Ranpeng;Lithgow-Bertelloni, Carolina;Stixrude, Lars
• 通讯作者: Stixrude, Lars

Changes in core-mantle boundary heat flux patterns throughout the supercontinent cycle

• DOI: 10.1093/gji/ggae075
• 发表时间: 2024-04-09
• 期刊: GEOPHYSICAL JOURNAL INTERNATIONAL
• 影响因子: 2.8
• 作者: Dannberg，Juliane;Gassmoller，Rene;Sprain，Courtney
• 通讯作者: Sprain，Courtney