生物磁铁矿是微生物通过生物矿化产生的一类重要磁性矿物，在合适条件下会保存形成纳米级生物磁铁矿化石。近些年的大量研究表明生物磁铁矿化石在自然界中广泛存在，改变了之前人们认为其在地质记录中缺乏保存的传统观念。生物磁铁矿及其携载的磁性信号记录了一系列地球物理和环境演变等信息，如何定量、有效、准确解译其磁性记录是目前面临的重要挑战。申请人拟在最近生物磁铁矿研究的重要进展之上，围绕其性质特征信息提取和磁性记录定量解译，具体开展：1.通过计算机图像分析和三维有限元微磁模拟，发展完善生物磁铁矿颗粒和磁性特征的定量分析方法，确定其岩石磁学性质变化范围及其敏感影响因素；2.验证并建立基于生物磁铁矿的古环境示踪方法，特别是追踪海底氧气含量演变；3.通过分析大洋钻探岩芯中的生物磁铁矿记录，探索其在海洋碳循环和新生代环境转变中的指示作用。此研究对开发和拓展生物磁铁矿在海洋地质和地球物理的应用有重要科学意义

Biogenic magnetite produced by magnetotactic bacteria is an important type of terrestrial magnetic minerals. Under suitable conditions, biogenic magnetite nanoparticles can be preserved in geological records as magnetofossils. Recent studies show that biogenic magnetite is widespread in the geological records, changing the conventional view that biogenic magnetite nanoparticles are prone to be dissolved in natural environments. Biogenic magnetite and the associated magnetic signals carry important geophysical and environmental information. Quantitative, efficient, and accurate interpretations of its magnetic signals are currently challenging. Building upon recent progress on biogenic magnetite from the applicant’s group, this proposal aims to develop advanced analytical approaches for extracting key information from biogenic magnetic assemblages, and to make quantitative geophysical/environmental interpretations of magnetofossil records. Specific projects include: 1. Using image processing techniques and three-dimensional micromagnetic modelling, developing suitable tools that can quantitatively extract key morphological information and magnetic properties of magnetofossil assemblages, producing ‘database’ with their magnetic property variations; 2. Testing and establishing magnetofossil as a sensitive environmental indicator, particularly for tracing changes in bottom ocean oxygenation; 3. Using magnetofossil records of ocean drilling cores from South Indian Ocean and Southwest Pacific to investigate marine carbon cycles and rapid environmental shifts during the Cenozoic. The proposed project will establish the value of biogenic magnetite in a wide range of applications in marine geology and geophysics.