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

有些岩石在形成时，就像磁带一样，从而证明了地球磁场在时间上的记录。来自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、磁地层学和古代地磁场行为的研究。在过去的四十年里，许多利用岩石磁矢量的研究得出的基本假设是，地球磁场的平均方向与以地球为中心、与自转轴对齐的磁棒所产生的方向相对应。这意味着古代磁场方向的倾角从（古）赤道附近的水平方向到（古）两极附近的垂直方向不等。假设古地磁数据具有足够的精度，可以用来重建岩石圈板块随时间的位置。最近，研究人员开始重新审视古代地磁场模型的基础数据，并发现现有数据库中最明显的缺陷是缺乏高质量的数据，包括来自北纬高纬度地区的场强信息。有可能是固体的地核影响了地球磁场的产生，而磁场的产生发生在流体的地核中。与地球自转轴平行且与内核相切的圆柱体（切线圆柱体）内的对流状态被认为是不同的。因此，切线柱面北（或南）的数据在地磁理论中具有特殊的意义，并且是检验古地磁研究的一个基本原则的有效性的关键。对这种高纬度火山进行取样的机会很少。来自斯克里普斯海洋学研究所的研究人员与他们的挪威合作者一起，正在对扬马延岛的合适地点进行古地磁采样和分析，扬马延岛是冰岛东北部沿大西洋中部裂谷的北极偏远火山岛。这项研究的样本产生了高质量的古地磁、古强度和北纬高纬度地区的地质年代学数据，这些数据对于增强对古长期变化、时间平均场及其长期变化的理解至关重要。这项研究的地质年代学工作由俄勒冈州立大学的合作者进行，为这个孤立的火山岛上的岩浆活动的年龄和持续时间提供了更好的理解。除了这项工作的科学目标之外，该项目还有助于培训和支持斯克里普斯大学的博士研究员，他们是地球科学领域一个代表性不足的群体的成员，研究结果正在用于有利于开发K-12教材和国家科学教师协会网络研讨会的推广活动。

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.