MicroPI: A micromagnetic approach to absolute palaeointensity determinations

MicroPI：绝对古强度测定的微磁方法

• 批准号: NE/Z000068/1
• 负责人: Wyn Williams
• 金额: $ 112.04万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2024
• 资助国家: 英国
• 起止时间: 2024 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FZ000068%2F1
• 关键词: MicroPI; micromagnetic; approach; absolute; palaeointensity

The physical and chemical processes that occur deep within the Earth have shaped the evolution of our planet over billions of years. We have very few tools that can be used to investigate the deep Earth over its entire geological history. One such tool is the analysis of magnetic recordings of the geomagnetic field made by rocks.The geomagnetic field is generated within the Earth's core more than 3000 km below the surface, and its behaviour is modified by the varying chemistry and sources of heat that have been slowly changing since the Earth's formation 4.5 billion years ago. The changes in the geomagnetic field are recorded by rocks when they form. By sampling and analysing the magnetic recordings of rocks, we can play back this recording of the changing geomagnetic field over time, and use this information to test the various theories of the evolution of our planet. In addition, knowledge of the ancient geomagnetic field also allows us to determine habitability on the early Earth's surface, as the geomagnetic field is known to protect and preserve the atmosphere from Solar radiation stripping.Unlike highly uniform man-made magnetic recording media, rocks contain a wide variety of magnetic particles of different shapes and sizes. These magnetic particles are known to display complex magnetic behaviours; however, until now a very simplified model has been used to explain and determine the ancient geomagnetic field intensities recorded by rocks. This means that the theory we presently use to extract ancient geomagnetic field information from rocks is incorrect, leading to errors in estimates of the ancient field intensity. This casts doubt on our current view of the how the geomagnetic field intensity has varied in the past, and also likely explains inconsistencies in multiple studies where different results are obtained from rocks of the same age.In the last year, the proposers of this project have developed a new theoretical model which accurately captures the complex behaviour of the magnetisations recorded within rocks. In this project, we propose to use our new understanding of how magnetic minerals record the geomagnetic field to build a completely new and different approach for determining ancient geomagnetic field intensities recorded in rocks. This new method will rely on a large numerical database of magnetic characteristics of different types of magnetic particles that have been simulated from numerical models. We will make this new method available to the scientific community through a web-app, where Earth Scientists can upload their own experimental measurements and can calculate estimates of palaeomagnetic field intensities using our new method.With our new approach we will investigate one of the most pressing issues of our times concerning heat and heat flow within the Earth over the last 4.5 billion years: when did the solid Inner Core nucleate? There are some published palaeomagnetic data to suggest that it is as recent as ~500 million years ago, though this is widely disputed. We will use our new approach to determine the reliability of these magnetic data, and to better pinpoint the timing of Inner Core Nucleation.

地球内部发生的物理和化学过程已在数十亿年内塑造了我们星球的发展。我们很少有工具可以用来调查整个地质历史上的深层地球。这样的工具是对岩石制造的地磁场的磁性记录的分析。地球核心内生成地面磁场内生成的地面以上超过3000公里，其行为被不同的化学和热量来源而改变，自从地球的形成以来，这种变化的热源一直在缓慢变化。地磁场的变化是由岩石形成时记录的。通过对岩石的磁记录进行采样和分析，我们可以随着时间的推移播放不断变化的地磁场的记录，并使用此信息来测试我们星球演变的各种理论。此外，对古代地磁场的知识还使我们能够确定地球早期表面上的可居住性，因为已知地磁领域可以保护和保护大气免受太阳辐射剥离。已知这些磁性颗粒显示复杂的磁性行为。但是，直到现在，一个非常简化的模型已被用来解释和确定岩石记录的古代地磁场强度。这意味着我们目前用来从岩石中提取古代地磁田地信息的理论是不正确的，导致对古代田间强度的估计错误。这对我们目前对过去的地磁场强度如何变化的看法产生了怀疑，并且也可能解释了在多项研究中的不一致性，这些研究从同一年龄的岩石中获得不同的结果。去年，该项目的建议者开发了一种新的理论模型，可以准确捕获岩石中记录的磁性复杂行为。在这个项目中，我们建议利用对磁性矿物如何记录地磁场的新理解，以建立一种全新的和不同的方法来确定岩石中记录的古代地磁场强度。这种新方法将依赖于已从数值模型模拟的不同类型磁性颗粒的磁性特性的大数字数据库。 We will make this new method available to the scientific community through a web-app, where Earth Scientists can upload their own experimental measurements and can calculate estimates of palaeomagnetic field intensities using our new method.With our new approach we will investigate one of the most pressing issues of our times concerning heat and heat flow within the Earth over the last 4.5 billion years: when did the solid Inner Core nucleate?有一些已发表的古磁数据表明，这是最近大约5亿年前的，尽管这是广泛争议的。我们将使用新方法来确定这些磁数据的可靠性，并更好地确定内核成核的时机。