HR: 16:00h
AN: GP22B-01 INVITED     [PDF]
TI: Recent advances in the high-resolution description of time variations of the geomagnetic field in France and comparison with data of Western Europe.
AU: * Lanos, P
EM: philippe.lanos@univ-rennes1.fr
AF: CNRS UMR6566, University of Rennes 1 Laboratory of Archaeomagnetism Campus of Beaulieu, RENNES, 35042 France
AB: Archaeomagnetism can provide a high-resolution full-vector description of the geomagnetic field, but the uncertainties associated to the reference data pose some specific problems. Archaeomagnetic data from archaeological structures (sites) such as hearths, kilns or sets of potteries, bricks or tiles, generally exhibit large experimental errors and are associated with more or less well constrained dates given by stratigraphic sequences (relative chronology), archaeological evidences, historical records or chronometric methods (radiocarbon, thermoluminescence.). The aim is to combine these different sources of information in order to get the best estimate of the past geomagnetic field. Research in archaeomagnetism in France has been particularly productive during the last two decades and addressed different methodological aspects: data acquisition, magnetic corrections (in particular, correction of the TRM anisotropy and cooling rate effects), allowance for the dating uncertainties, curve estimation, application to dating and to geomagnetism. An efficient sampling policy in close co-operation with archaeologists (in the framework of rescue archaeology) associated with the development of new statistical tools (statistical modelling of the sampling strategies, new moving average techniques, Bayesian statistics applied to curve building), and with the study of the magnetic properties of baked clays, permits to significantly constrain the secular variation at century and millennium scales. Precise reference curves of the directional variations of the geomagnetic field over the last three thousand years can be defined. At the same time, studies of the intensity have been relaunched on sites in France and Middle East, with some particular attention on to cooling rate dependence of the thermoremanent magnetization. Comparisons with other recent results from Western Europe will be presented and applications to geomagnetic modelling and to dating will be discussed.
DE: 1500 GEOMAGNETISM AND PALEOMAGNETISM
DE: 1503 Archeomagnetism
SC: Geomagnetism and Paleomagnetism [GP]
MN: 2003 Fall Meeting