Palacomagnetic and rock magnetic investigation of Late Pleistocene loess deposits in Belgium

The results of a palaeomagnetic and rock magnetic investigation of two loess profiles of Late-Pleistocene age in Tongrinne (TG) and Rocourt (RC) in Belgium are given. We examined the possibility of using this type of sediment, which is, strictly speaking, eolian in origin, to gain information about the dynamic behaviour of the ancient geomagnetic field. The influence of geological processes, especially those known to occur in periglacial environments, were examined. A field test was applied to the upturned strata near a fossil frost wedge of Weichselian age in Tongrinne to demonstrate that at least some large directional changes found in periglacial sediments, and which could be mistaken for ‘excursions’, cannot be attributed to the Earth's magnetic field, but are due to mechanical disturbances. The DRM/ARM method and the requirements for uniformity by Levi et al. to obtain relative geomagnetic palaeointensities were tested on those loess deposits which contain a large silt fraction.