Origin of magnetic fabric in bricks: its implications in archaeomagnetism
Earth and related Environmental sciences
Anisotropy of magnetic susceptibility
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Comparison with the magnetic anisotropy of unbaked (onldy dried) and baked loam bricks, hand moulded in a rectangular frame, reveals that the same moulding technique had been applied to produce the bricks of a Medieval brick kiln that was archaeomagnetically dated at 1650 AD [Geoarchaeology (to be published)]. Anisotropy of magnetic susceptibility (AMS) measurements show that the unbaked and baked bricks have a shape-related magnetic fabric, induced during the moulding process, with average Kmax occurring in the greatest faces along the direction of the longest edges and Kmin perpendicular to the greatest faces of the bricks. The anisotropy of thermoremanence (ATRM) is high, indicating that the remanence directions of bricks may accuse large deviations from the geomagnetic field direction responsible for it. However, anisotropy seems unldikely to be the cause for the apparent discrepancy between the archaeomagnetical and archaeological date of the brick kiln, the latter presumably about half a century older. Besides AMS, also the anisotropy of anhysteretic remanence was examined as a possible substitute for ATRM and to obtain information on the magnetic state of the minerals contributing to the remanence anisotropy.
CitationHus, J.; Ech-Chakrouni, S.; Jordanova, D. (2002). Origin of magnetic fabric in bricks: its implications in archaeomagnetism. , Issue 0, IRM,