Secular variation in Permian red beds from Dôme de Barrot, SE France

The Dôme de Barrot red beds (SE France) were deposited during the Permo¯Carboniferous Reversed Superchron (PCRS), near the palaeo-equator. The natural remanent magnetisation (NRM) resides in detrital hematite, which is very resistant against thermal demagnetisation. Microprobe analyses reveal the presence of titanium in hematite grains, indicating the volcanic and thus detrital origin. Therefore, the NRM is a detrital remanent magnetisation and NRM variations reflect changes in the geomagnetic field. Tuning of the proxy parameter magnetic susceptibility to periods of the Earth orbit during Permian times provides relative time control. The inferred average sedimentation rate is 11.8 cm 1000 yr-1. The variation in NRM directions is similar to present-day secular variation (SV). This suggests that SV was not suppressed during (at least part of) the PCRS.