Redeposition experiments with natural sediments from the SE Black Sea in magnetic fields between about 2 and 114 μT

Diluted slurry with an initial density of 1.30 g cm(-3) prepared from natural glacial Black Sea sediments was deposited under controlled field conditions between 1.72 and 114.21 mu T. Compaction was achieved by evaporation of a portion of the pore water from the open sample boxes over 4-7 d until a density of about 1.44-1.55 g cm(-3) was reached. Magnetizations M acquired in a magnetic field B follow a slightly non-linear function with M similar to B-0.82. Similar relationshipswere also obtained for palaeointensity estimates for the artificial samples by using normalization by low-field susceptibility, anhysteretic remanent magnetization and saturation magnetization. All samples are characterized by a magnetic fabric typical for natural sediments as checked by determining the anisotropy ofmagnetic susceptibility. The sediments' anisotropy is in the range of 6-7 per cent and it is characterized by an oblate anisotropy ellipsoid with its small axis perpendicular to the deposition plane. According to scanning electron microscope imaging low-Ti magnetite particles present in the used sediments are in the range of 1-30 mu m with the majority of particles 2-5 mu m in size. Obtained results confirm the conclusion from other magnetostratigraphic studies that the Laschamps geomagnetic polarity excursion in the Black Sea area exhibited field values as low as 2.8 mu T in its transitional phase between normal and reversed polarity.

Automated summary

The study conducted experiments on diluted slurry prepared from natural glacial Black Sea sediments, revealing a slightly non-linear function relationship between magnetization and magnetic field in the artificial samples used. Normalization calculations showed that all samples exhibit a typical magnetic fabric of natural sediments with an anisotropy range of 6-7%.