Collaborative Research: The Time Averaged Field Initiative: Addressing a Critical Data Gap

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Paleomagnetic data 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 (which we call paleo-geomagnetism). Ever since its inception, the key assumption in many paleomagnetic studies has been that the average direction of the paleomagnetic field corresponds to one that would have been produced by a geocentric axial dipole (GAD), and that the dip of the magnetic field from the horizontal plane provides data of sufficient accuracy to enable their use in plate reconstructions. This proposal will enhance the underlying data that go into time averaged field models, which assess the degree to which the geomagnetic field can be considered "GAD". What is required are data sets with more than 100 sampling sites from all over the globe. To be of most value the data sets would have both directional and intensity data and have excellent age control. The quality required for meaningful interpretation of the data mean that there are very few places on Earth that have adequate coverage. The task at hand is daunting and must be attacked one study at a time. We propose here to exploit the potential of the volcanic fields of Israel, for which there is an enormous amount of preliminary data in the form of both paleomagnetic directions and K-Ar and 40Ar/39Ar dates. This proposal concerns the understanding of one of the most important physical properties of planet Earth, its magnetic field. Magnetic fields are vectors with both direction and strength. While obtaining ancient field directions is relatively straight-forward, extracting accurate ancient field strength information is not. We propose here to attempt to obtain the full vector information and couple it with accurate age information for a 4-D look at the ancient magnetic field as recorded in the volcanics of Israel. This work can contribute to the understanding of many fundamental processes, including the motions of tectonic plates, the role of the inner core in controlling the geomagnetic field, and establishing the average strength of the magnetic field to place recent observations in perspective. Constraints on the geomagnetic field are important to those who study the dynamical processes in Earth?s deep interior. Also, it will serve as the doctoral dissertation project of a graduate student.