Understanding rapid changes in Earth's magnetic field: timing, spatial extent, and causes of geomagnetic spikes and excursions

地球不断变化的磁场是由地球外核中导电流体的地球动力学运动产生的。磁场的快速和极端变化不仅危及地球对有害宇宙射线和太阳风的磁屏蔽保护，还对支撑现代社会的导航技术和电子基础设施构成严重威胁。令人担忧的是，过去数万年的古地磁记录显示，地磁场经历了快速漂移和尖峰事件，在此期间，其强度要么下降到现在水平的几分之一，要么显示出比现在和历史场中所观察到的任何极值都大的极值。这些极端的变化对地球发电机的动力产生了至关重要的制约。然而，缺乏来自关键地点的过时、高分辨率和连续记录，使我们无法回答许多基本问题。例如，地磁尖峰/漂移是在原地增长/衰减，还是在空间上随时间移动？该项目旨在通过利用全球纵向断面的多种地质档案，以前所未有的分辨率重建地磁漂移和尖峰事件的连续记录，从而改变我们对该领域极端和快速变化的理解。

Earth's constantly changing magnetic field is generated by the geodynamic motion of electrically conductive fluid in Earth's outer core. Rapid and extreme changes of the field not only compromise Earth's magnetic shielding protection from harmful cosmic rays and solar wind but also pose serious threat to the navigation technology and electrical infrastructure that underpin modern society. Alarmingly, palaeomagnetic records covering the last few tens of thousand years reveal that geomagnetic field has experienced rapid excursions and spike events during which its intensity either drops to only a few percent of the present level or show extreme values greater than any observed in present and historical field. These extreme changes place crucial constraints on the dynamics of the geodynamo. Yet, the lack of well dated high-resolution and continuous records from key locations has prevented us from answering many basic questions. For example, do geomagnetic spikes/excursions grow/decay in situ or move spatially through time? This project aims to make a step change in our understanding of extreme and rapid changes of the field by reconstructing continuous records of geomagnetic excursion and spike events at unprecedented resolution using multiple types of geological archives from a longitudinal transect around the globe.