Apparent palaeomagnetic low-inclination excursion in a pre-consolidated continental shelf sediment

The presence of an almost exact 180° change in declination in a piston-core from the continental margin off the west coast of Norway is associated with two distributions of positive inclination of the remanent directions which could have been interpreted to represent an excursion of the geomagnetic field. The over-consolidated top section, defined by anomalously low-inclination directions, reveals a magnetic fabric typical of slurries or deposits affected by water currents, as opposed to an anomalous fabric in the lower section associated with magnetic directions coinciding with the present geomagnetic field. The sampling area reveals seismic features indicative of slumping, erosion and redeposition, which are also reflected by micropalaeontological evidence. It is concluded that the pre-consolidated top-section has been transported by slumping, the anomalously low-dipping directions resulting from processes acting during the initial consolidation.