CSEDI Collaborative Research: Towards a unified model of the geomagnetic, geochemical, and thermal evolutions of Earth's mantle and core

CSEDI 合作研究：建立地幔和地核地磁、地球化学和热演化的统一模型

• 批准号: 1361228
• 负责人: Dave Stegman
• 金额: $ 4.04万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-05-01 至 2016-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1361228&HistoricalAwards=false
• 关键词: CSEDI; Collaborative; Research; Towards; unified

The magnetic field of the Earth, generated inside the fluid portion of Earth's Iron core, protects the Earth and orbiting satellites from a barrage of potentially harmful charged particles streaming through space. The magnetization of ancient rocks has shown us that the magnetic field has been shielding Earth for at least 3.5 billion years. Beyond that age, there are no observations currently available to assess if a magnetic field was present. It is a mystery when exactly the magnetic field arose, and also a challenging puzzle as to how it has been sustained for billions of years. The answers to those questions will greatly impact our understanding of how our Earth evolved from its initial state into a habitable planet able to develop and sustain life on its surface. The proposed research aims to take a new approach to answer these difficult questions by looking at the role a deep magma ocean overlying Earth's core might have played in helping sustain an ancient magnetic field. Recent experiments that are able to simulate the extreme pressures and temperatures within Earth's deep interior have provided new knowledge on how Earth materials behave under such conditions. Using this recently gained information on material properties, in conjunction with theoretical considerations of the energetics of magnetic field generation, this project will build physics-based models of Earth's interior and cooling through time. These efforts will specifically investigate scenarios in which there is a long-lived magma ocean on top of the core. These models will test if this scenario can explain the generation of Earth's magnetic field during ancient times. While we will learn directly about the Earth's deep interior, this work impacts our understanding of surface processes as well, since the magnetic shielding of highly charged particles aimed at Earth (or lack thereof) will affect the atmosphere and surface of the Earth.

地球的磁场是在地球铁核的流体部分内部产生的，它保护地球和绕轨道运行的卫星免受太空中流动的潜在有害带电粒子的影响。 古代岩石的磁化向我们表明，磁场已经屏蔽了地球至少35亿年。 超过这个年龄，目前还没有观测结果可以评估是否存在磁场。 磁场究竟是何时产生的，这是一个谜，也是一个具有挑战性的难题，它是如何持续了数十亿年。 这些问题的答案将极大地影响我们对地球如何从最初状态演变成一个能够在其表面发展和维持生命的可居住星球的理解。 这项拟议中的研究旨在采取一种新的方法来回答这些难题，方法是研究覆盖在地核上的深层岩浆海洋在帮助维持古代磁场方面可能发挥的作用。最近的实验能够模拟地球内部深处的极端压力和温度，为地球材料在这种条件下的行为提供了新的知识。 利用最近获得的关于材料特性的信息，结合对磁场产生的能量学的理论考虑，该项目将建立地球内部和随时间冷却的物理模型。 这些努力将专门调查在地核顶部存在长期岩浆海洋的情况。 这些模型将测试这种情况是否可以解释古代地球磁场的产生。 虽然我们将直接了解地球的深层内部，但这项工作也会影响我们对表面过程的理解，因为针对地球的高电荷粒子的磁屏蔽（或缺乏磁屏蔽）将影响地球的大气和表面。