Integrated Mineralogic and Rock Magnetic Study of Silicate-Hosted Magnetization

这项研究将阐明与硅酸盐中磁铁矿晶体取向包裹体（COMIS）相关的独特稳定磁化的起源。这些特征在各种火成岩和变质岩类型的几种矿物中很常见，以前的工作表明它们保存了关于地球古代磁场的异常强大的信息。 这项工作将结合联合收割机亚微观矿物学技术，包括扫描和透射电子显微镜，电子背散射衍射，原子和磁力显微镜，以确定如何COMIS形成。岩石磁性分析结合磁力显微镜将用于确定这些功能获得其磁化的具体机制。这些研究将侧重于来自许多不同地质时代和环境的样本。从海底钻取的一套样品将用于评估COMIS是否可能对海洋磁异常负责的悬而未决的问题，对海洋磁异常的认识导致了板块构造理论。该项目的一个重要目标是完善对单个硅酸盐晶体进行岩石磁性分析的方法，包括制定确定地质历史中地球磁场强度和方向的方法。关于磁场演化的信息对磁场起源的地核的演化有影响。这项研究还有望为推断2亿年前没有海底记录的岩石圈板块构造运动提供更好的依据。该项目将涉及一名博士生，并与国家实验室，国家设施和其他学术机构的同事合作。

EAR-0309686RenneThis study will clarify the origin of uniquely stable magnetizations associated with crystallographically oriented inclusions of magnetite in silicates (COMIS). These feature are common in several minerals in various igneous and metamorphic rock types, and previous work shows that they preserve exceptionally robust information about Earth's ancient magnetic field. This work will combine submicroscopic mineralogical techniques, including scanning and transmission electron microscopy, electron backscattered diffraction, atomic and magnetic force microscopy, to determine how COMIS form. Rock magnetic analyses combined with magnetic force microscopy will be used to determine the specific mechanisms by which these features acquire their magnetizations. These studies will focus on samples from many different geologic ages and environments. A suite of samples drilled from the sea-floor will be used to evaluate the outstanding question of whether COMIS could be responsible for oceanic magnetic anomalies, whose recognition led to the theory of plate tectonics. A significant goal of the project is to perfect methods for rock-magnetic analysis of individual silicate crystals, including development of methods for determining the intensity and orientation of Earth's magnetic field in the geologic past. Information about the evolution of the magnetic field has implications for the evolution of Earth's core, where the magnetic field originates. The study is also expected to yield an improved basis for deducing plate tectonic movements of the lithosphere for times prior to 200 million years ago when the sea-floor record is nonexistent. The project will involve a PhD student and collaboration with National Labs, National Facilities, and colleagues at other academic institutions.