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: 1361221
• 负责人: Joseph Stoner
• 金额: $ 15.4万
• 依托单位: Oregon State University
• 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=1361221&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.

地球磁场在地球铁核的流体部分产生，保护地球和轨道上的卫星不受流经太空的潜在有害带电粒子的影响。古老岩石的磁化向我们表明，磁场至少已经屏蔽了地球35亿年。在这个年龄之后，目前还没有观测到的数据来评估是否存在磁场。这是一个谜，磁场究竟是什么时候产生的，也是一个具有挑战性的谜题，它是如何维持了数十亿年的。这些问题的答案将极大地影响我们对地球如何从最初的状态演变为能够在其表面发展和维持生命的宜居行星的理解。这项拟议的研究旨在采取一种新的方法来回答这些困难的问题，方法是研究覆盖在地核上的深岩浆海洋在帮助维持古老磁场方面可能发挥的作用。最近能够模拟地球深处极端压力和温度的实验，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性质的信息，结合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基于物理的模型。这些努力将专门调查在核心顶部存在长期岩浆海洋的情况。这些模型将测试这一情景是否能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，但这项工作也影响了我们对地表过程的理解，因为针对地球(或缺乏高电荷粒子)的高电荷态粒子的磁屏蔽将影响地球的大气和表面。