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'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.