Toward a full vector model of depositional remanent magnetization and the global sedimentary paleointensity data base

地磁场既是保护伞，保护我们不受宇宙辐射的影响，也是一扇窗户，让我们得以一窥地球内部的运作情况。地磁场的古代记录可以告诉我们早期地球的动力学和边界条件随时间的变化。由于其本质上的偶极性质，该磁场起到了向导的作用，指向自转轴，从而为勘探者和地质学家提供了纬度信息。人类对地磁场的测量可以追溯到大约一千年前，而在大约400年前之前的测量非常稀少。关于磁场在过去的作用的知识依赖于地质和考古材料的磁化所带来的偶然记录。从这些材料中获得有意义的信息需要了解复杂的记录过程，这对于大多数天然材料来说是知之甚少的，因为这些材料偏离了理想的理论。在沉积物和沉积岩中发现了地磁场历史的一些最重要的档案。这种材料可以保存地磁场矢量的准连续记录，可以转化为时间序列，具有相当严格的年龄控制。由于沉积物和沉积岩具有许多优点，60多年来一直是古地磁学家们深入研究的对象。已有100多篇文献报道了基于沉积物质的古地磁强度研究结果。然而，沉积物是如何被磁化的，以及如何最好地获取地磁场矢量，人们仍然没有很好地理解。这就是本提案的主题。在这项研究中，我们正在构建数值模型，旨在解释我们在严格控制的条件下通过实验室再沉积实验获得的实验数据。这些模型可以用来做出特定的预测，并对已发布的数据集进行测试。我们的工作对整个地球科学产生了重大影响，有助于理解地球最重要的物理特性之一，即磁场。它将有助于理解许多基本过程，包括古地磁数据中的板块运动约束，内核在控制地磁场中的作用，以及建立偶极矩的平均强度，以正确地看待最近的观测结果。地磁场的约束对于研究地球深部内部动力学过程的深地界人士来说是非常重要的。通过这笔拨款，我们将扩大可公开访问的磁信息数据库（MagIC），极大地扩展其对更广泛的地球科学社区的效用。随着地球磁场在气候系统中的作用受到越来越多的关注，这一点尤为重要。最后，它将作为斯克里普斯海洋学研究所研究生的博士论文项目。

The geomagnetic field acts both as an umbrella, shielding us from cosmic radiation and as a window, offering one of the few glimpses of the inner workings of the Earth. Ancient records of the geomagnetic field can inform us about dynamics of the early Earth and changes in boundary conditions through time. Thanks to its essentially dipolar nature, the field has acted as a guide, pointing to the axis of rotation thereby providing latitudinal information for both explorers and geologists. Human measurements of the geomagnetic field date to about a millenium and are quite sparse prior to about 400 years ago. Knowledge of what the field has done in the past relies on accidental records carried by the magnetization of geological and archaeological materials. Obtaining meaningful information from such materials requires an understanding of complex recording processes, which are poorly understood for most natural materials as these deviate from the ideal tractable to theory. Some of the most important archives for the history of the geomagnetic field are found in sediments and sedimentary rocks. Such materials can preserve quasi-continuous records of the geomagnetic field vector, which can be turned into time series with rather tight age control. Because of their many advantages, sediments and sedimentary rocks have been the subject of intense study by paleomagnetists for over sixty years. There are over 100 publications reporting results of ancient field intensity based on sedimentary materials. Yet how sediments get magnetized and how best to retrieve the geomagnetic field vector are still not well understood. This is the topic of the present proposal. In this study, we are constructing numerical models designed to explain experimental data that we are obtaining through laboratory redeposition experiments under carefully controlled conditions. These models with then be used to make specific predictions testable with published data sets. Our work has significant impacts throughout the geosciences, contributing to the understanding of one of the most important physical properties of planet Earth, its magnetic field. It will contribute to the understanding of many fundamental processes, including plate motion constraints from paleomagnetic data, the role of the inner core in controlling the geomagnetic field, and establishing the average strength of the dipole moment to place recent observations in perspective. Constraints on the geomagnetic field are important to those in the deep Earth community who study the dynamical processes in Earth's deep interior. Through this grant we will augment the publicly accessible database for magnetic information (MagIC), greatly expanding its utility to the broader geoscience community. This is particularly important as the role of the Earth's magnetic field in the climatic system undergoes increased scrutiny. Finally, it will serve as the doctoral dissertation project of a graduate student at the Scripps Institute of Oceanography.