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Gee, JS, Tauxe L, Constable C.  2008.  AMSSpin: A LabVIEW program for measuring the anisotropy of magnetic susceptibility with the Kappabridge KLY-4S. Geochemistry Geophysics Geosystems. 9   10.1029/2008gc001976   AbstractWebsite

Anisotropy of magnetic susceptibility (AMS) data are widely used as a petrofabric tool because the technique is rapid and nondestructive and because static measurement systems are capable of determining small degrees of anisotropy. The Kappabridge KLY-4S provides high resolution as a result of the large number of measurements acquired while rotating the sample about three orthogonal axes. Here we describe a graphical-based program called AMSSpin for acquiring AMS data with this instrument as well as a modified specimen holder that should further enhance the utility of this instrument. We also outline a method for analysis of the data (that differs in several ways from that of the software supplied with the instrument) and demonstrate that the measurement errors are suitable for using linear perturbation analysis to statistically characterize the results. Differences in the susceptibility tensors determined by our new program and the SUFAR program supplied with the instrument are small, typically less than or comparable to deviations between multiple measurements of the same specimen.

Genevey, A, Gallet Y, Constable CG, Korte M, Hulot G.  2008.  ArcheoInt: An upgraded compilation of geomagnetic field intensity data for the past ten millennia and its application to the recovery of the past dipole moment. Geochemistry Geophysics Geosystems. 9   10.1029/2007gc001881   AbstractWebsite

This paper presents a compilation of intensity data covering the past 10 millennia (ArcheoInt). This compilation, which upgrades the one of Korte et al. (2005), contains 3648 data and incorporates additional intensity and directional data sets. A large majority of these data (similar to 87%) were acquired on archeological artifacts, and the remaining similar to 13% correspond to data obtained from volcanic products. The present compilation also includes important metadata for evaluating the intensity data quality and providing a foundation to guide improved selection criteria. We show that similar to 50% of the data set fulfill reasonable reliability standards which take into account the anisotropic nature of most studied objects (potsherds), the stability of the magnetization, and the data dispersion. The temporal and geographical distributions of this sub-data set are similar to those of the main data set, with similar to 72% of the data dated from the past three millennia and similar to 76% obtained from western Eurasia. Approximately half of the selected intensity data are associated with at least an inclination value. To constrain the axial and full dipole evolution over the past three millennia requires that we avoid any overrepresentation of the western Eurasian data. We introduce a first-order regional weighting scheme based on the definition of eight widely distributed regions of 30 degrees width within which the selected data are numerous enough. The regional curves of virtual axial dipole moments (VADM) and of mixed VADM-virtual dipole moments (VDM) averaged over sliding windows of 200 years and 500 years testify for strong contributions from either equatorial dipole or nondipole components. The computation of global VADM and mixed VADM/VDM variation curves, assuming an equal weight for each region, yields a dipole evolution marked by a distinct minimum around 0 B.C./A.D. followed by a maximum around the third-fourth century A. D. A second minimum is present around the eighth century A. D. This variation pattern is compatible with the one deduced from earlier, more sophisticated analysis based on the inversion of both intensity and directional data. In particular, there is a good agreement among all VADMs and dipole moment estimates over the historical period, which further strengthens the validity of our weighting scheme.