EAGER: Determining When Earth's Magnetic Field Originated

EAGER：确定地球磁场的起源时间

• 批准号: 1226293
• 负责人: Benjamin Weiss
• 金额: $ 8.76万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2014-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1226293&HistoricalAwards=false
• 关键词: EAGER; Determining; When; Earth; Magnetic

It is currently unknown when the Earth?s magnetic field originated. This timing has major implications for the thermal evolution of the interior, the physics of dynamo action, and the evolution of the terrestrial atmosphere. Paleomagnetic studies of the oldest known unmetamorphosed rocks indicate that a field with intensity similar to that of the present existed at least 3.5 billion years (Ga) ago. Here we describe a project that could potentially determine its time of origin and earliest evolution. Detrital zircon crystals found in sandstones from the Jack Hills of Western Australia are the oldest known earthly materials. Ranging from 3.0-4.38 Ga in age, they may preserve a record of the origin of Earth?s geodynamo. Some of these zircons carry an extremely weak remanent magnetization. Depending on their thermal and alteration histories, the Jack Hills zircons may therefore provide the earliest known paleointensity records of the Earth?s field. The PIs will conduct research that will help determine the time when the Earth's magnetic field began. This is important for understanding how the planet has evolved over time. The PIs plan to share theirr results in public lectures at local science museums and as part of podcasts and local science festivals. They also plan to share results at multidisciplinary conferences. The PIs will train MIT undergraduates in research techniques. Finally, this project will further stimulate the development of next generation paleomagnetism techniques for the analysis of extremely weakly magnetic materials.

目前尚不清楚地球何时会出现？磁场的起源。 这一时间对内部的热演化、发电机作用的物理学和地球大气的演化具有重要意义。 对已知最古老的未变质岩石的古地磁研究表明，至少在35亿年前（Ga）存在一个强度与现在相似的磁场。 在这里，我们描述了一个可能确定其起源时间和最早进化的项目。 在西澳大利亚杰克山的砂岩中发现的碎屑锆石晶体是已知的最古老的地球材料。 年龄在3.0-4.38 Ga之间，它们可能保存了地球起源的记录。地球发电机。 其中一些锆石带有极弱的剩磁。 根据它们的热历史和蚀变历史，杰克山的锆石可能因此提供了地球已知最早的古强度记录。s字段。PI将进行研究，以帮助确定地球磁场开始的时间。 这对于了解地球如何随着时间的推移而演变很重要。 PI计划在当地科学博物馆的公开讲座中分享他们的成果，并作为播客和当地科学节的一部分。 他们还计划在多学科会议上分享成果。 PI将在研究技术方面培训麻省理工学院的本科生。 最后，该项目将进一步促进下一代古地磁技术的发展，用于极弱磁性材料的分析。