Collaborative Research: Geomagnetic Field as Recorded on Iceland and Jan Mayen: Key to Field Structure at High Northern Latitudes

一些岩石在形成时就像磁带一样，从而证明了地球磁场在时间上的记录。这些记录的数据在地球的各种地球物理研究中发挥着重要作用，包括板块构造重建、磁性地层学和研究古代地磁场的行为。在过去的40年里，许多研究使用从岩石中获得的磁矢量做出的基本假设是，地球磁场的平均方向对应于地球中心与自旋轴对齐的条形磁场所产生的方向。这意味着古代磁场方向的倾角从靠近(古)赤道的水平方向到靠近(古)极点的垂直方向不等。假设古地磁数据具有足够的精确度，使其能够用于重建随时间推移的岩石圈板块的位置。最近，研究人员开始重新检查古代地磁场的基本数据模型，并发现现有数据库中最明显的缺陷是缺乏来自北纬高纬度的高质量数据，包括有关磁场强度的信息。固体内核可能会影响地球磁场的产生，而磁场的产生发生在流体内核中。平行于地球自转轴、与内核相切的圆柱体(切线圆柱体)内部的对流状态被认为是不同的。因此，来自切圆柱体北(南)的数据在地磁学理论中具有特殊的意义，是检验古地磁研究基本原理之一的有效性的关键。对如此高纬度的火山进行采样的机会很少。斯克里普斯海洋研究所的研究人员与他们的挪威合作者一起，正在对扬马延进行古地磁采样和合适的地点分析，扬马延是北极中大西洋裂谷的一个偏远火山岛，位于冰岛东北部。这项研究的样品正在从北纬高纬度产生高质量的古地磁、古强度和地质年代学数据，这些数据对于加强对古分子变化、时间平均场及其长期变化的理解至关重要。这项研究的年代学工作由俄勒冈州立大学的合作者进行，有助于加深对这座与世隔绝的火山岛上镁铁质岩浆活动的年龄和持续时间的了解。除了这项工作的科学目标外，该项目还有助于培训和支持斯克里普斯的博士生研究员，他是地球科学中代表性不足的群体的一员，并将成果用于外联活动，这些活动有助于为全国科学教师协会编写K-12课程教材和网络研讨会。

Some rocks as they form, act like magnetic tape, thus proving recordings of the Earth's magnetic field through time. Data from such records play an important role in a variety of geophysical studies of the Earth, including plate tectonic reconstructions, magnetostratigraphy, and studies of the behavior of the ancient geomagnetic field. Over the past four decades the fundamental assumption made in many studies using the magnetic vectors coaxed from rocks has been that the average direction of the Earth's magnetic field corresponds to one that would have been produced by a bar magnetic centered in the Earth that is aligned with the spin axis. This implies that the dip of the ancient magnetic field directions vary from horizontal near the (paleo) equator to vertical near the (paleo) poles. The assumption is that paleomagnetic data are of sufficient accuracy to enable their use in reconstructing the positions of lithospheric plates through time. Recently, researchers have begun to reexamine the fundamental data underlying models of the ancient geomagnetic field and are finding that the most glaring deficiency in the existing data base is a dearth of high quality data, including information about the field strength, from high northerly latitudes. It is possible that the solid inner core influences the generation of the Earth's magnetic field, which takes place in the fluid outer core. The convective regimes inside a cylinder parallel to the Earth's rotational axis that is tangent to the inner core (the tangent cylinder) are thought to be different. Therefore, data from north (or south) of the tangent cylinder are of special interest in the theory of geomagnetism and are key to testing the validity of one of the fundamental tenets of paleomagnetic study. Opportunities to sample such high latitude volcanics are few and far between. Researchers from Scripps Institute of Oceanography, in conjunction with their Norwegian collaborators, are conducting paleomagnetic sampling and analysis of suitable sites from Jan Mayen, a remote volcanic island in the Arctic along the mid-Atlantic rift, northeast of Iceland. Samples from this study are producing high quality paleomagnetic, paleointensity, and geochronological data from high northern latitudes that are essential to an enhanced understanding of paleosecular variation, the time averaged field and its long term variations. Geochronologic work for this study, conducted by collaborators from Oregon State University, is providing an enhanced understanding of the age and duration of mafic magmatic activity at this isolated volcanic island. In addition to the scientific objectives of this work, the project is contributing to the training and support of doctoral researcher at Scripps who is a member of an underrepresented group in the earth sciences, and results are being used in outreach activities that benefit in the development of K-12 teaching materials and web seminars for the National Science Teacher Association.