HR: 0830h
AN: GP21B-0037    [PDF]
TI: Constraining the geomagnetic field intensity in Western Europe during the 17-19th centuries from French faience shards
AU: Rosen, J
EM: Jean.Rosen@u-bourgogne.fr
AF: UMR5594, Archeologie, cultures et societes, Universite de Bourgogne, bat. Sciences-Gabriel, 6 Bd Gabriel, Dijon, 21000 France
AU: Genevey, A
EM: agenevey@ucsd.edu
AF: Scripps Institution of Oceanography, GRD, UCSD, 9500 Gilman drive, La Jolla, CA 92093 United States
AU: Genevey, A
EM: agenevey@ucsd.edu
AF: Institut de Physique du Globe de Paris, Laboratoire de Paleomagnetisme, 4 place Jussieu, Paris, 75252 France
AU: * Gallet, Y
EM: gallet@ipgp.jussieu.fr
AF: Institut de Physique du Globe de Paris, Laboratoire de Paleomagnetisme, 4 place Jussieu, Paris, 75252 France
AB: We obtained new archeointensity results for France from the analysis of seven groups of potsherds precisely dated from the beginning of the 17th century to the 19th century. These earthenware shards were found during excavations in Nevers which was an important production center of faience in France during the 17-18th centuries. For our intensity determinations, we used a new variant of the Thellier and Thellier (1959) method. This procedure ("IZZI" method; Tauxe et al., 2003) involves the alternation of pair of heatings in field-zero field ("IZ" steps) and pair of heatings in zero field-in field ("ZI" steps), and was specially designed to detect biased intensity results due to multi-domain magnetic grains. The raw intensity values were corrected for TRM anisotropy and cooling rate effects. Our preliminary results do not show strong intensity variations during the 17-19th centuries. In particularly they do not exhibit a rapid intensity decrease during the 17th century as predicted in Western Europe from the global geomagnetic models of Jackson et al. (2000). To constrain their models during the 1590-1840 period, during which directional but no intensity geomagnetic measurements are available, these authors used a backward extrapolation made on the basis of the linear decay of the dipole moment observed since 1840. Our study challenges the validity of this extrapolation and contributes to our knowledge on the recent variation of the dipole moment of the geomagnetic field.
DE: 1503 Archeomagnetism
DE: 1521 Paleointensity
DE: 1522 Paleomagnetic secular variation
DE: 9335 Europe
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting