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。在过去的四十年里，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磁场。这意味着古代磁场方向的倾角从水平的(古)赤道附近到垂直的(古)极附近不等。假设古地磁数据具有足够的精度，使其能够用于重建随时间推移的岩石圈板块位置。最近，研究人员开始重新审查古代地磁场的基本数据基础模型，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)的数据对地磁学理论具有特殊的意义，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岩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正在对扬马延岛进行古地磁采样和分析，扬马延岛是北极中大西洋裂谷中的一个偏远火山岛，位于冰岛东北部。这项研究的样品正在从北半球高纬度产生高质量的古地磁、古强度和地质年代学数据，这些数据对于增强对古分子变化、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，这些活动有助于为国家科学教师协会编写K-12级教材和网络研讨会。

Some rocks as they form, act like magnetic tape, thus proving recordings of the Earth'smagnetic field through time. Data from such records play an important role in a varietyof geophysical studies of the Earth, including plate tectonic reconstructions,magnetostratigraphy, and studies of the behavior of the ancient geomagnetic field. Overthe past four decades the fundamental assumption made in many studies using themagnetic vectors coaxed from rocks has been that the average direction of the Earth'smagnetic field corresponds to one that would have been produced by a bar magneticcentered in the Earth that is aligned with the spin axis. This implies that the dip of theancient magnetic field directions vary from horizontal near the (paleo) equator to verticalnear the (paleo) poles. The assumption is that paleomagnetic data are of sufficientaccuracy to enable their use in reconstructing the positions of lithospheric platesthrough time. Recently, researchers have begun to reexamine the fundamental dataunderlying models of the ancient geomagnetic field and are finding that the most glaringdeficiency in the existing data base is a dearth of high quality data, including informationabout the field strength, from high northerly latitudes. It is possible that the solid innercore influences the generation of the Earth's magnetic field, which takes place in thefluid outer core. The convective regimes inside a cylinder parallel to the Earth'srotational axis that is tangent to the inner core (the tangent cylinder) are thought to bedifferent. Therefore, data from north (or south) of the tangent cylinder are of specialinterest in the theory of geomagnetism and are key to testing the validity of one of thefundamental tenets of paleomagnetic study. Opportunities to sample such high latitudevolcanics are few and far between. Researchers from Scripps Institute ofOceanography, in conjunction with their Norwegian collaborators, are conductingpaleomagnetic sampling and analysis of suitable sites from Jan Mayen, a remotevolcanic island in the Arctic along the mid-Atlantic rift, northeast of Iceland. Samplesfrom this study are producing high quality paleomagnetic, paleointensity, andgeochronological data from high northern latitudes that are essential to an enhancedunderstanding of paleosecular variation, the time averaged field and its long termvariations. Geochronologic work for this study, conducted by collaborators from OregonState University, is providing an enhanced understanding of the age and duration ofmafic magmatic activity at this isolated volcanic island. In addition to the scientificobjectives of this work, the project is contributing to the training and support of doctoralresearcher at Scripps who is a member of an underrepresented group in the earthsciences, and results are being used in outreach activities that benefit in thedevelopment of K-12 teaching materials and web seminars for the National ScienceTeacher Association.