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

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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.