Reliability of the natural remanent magnetization recorded in Chinese loess

Abstract

Chinese loess‐paleosol sequences undoubtedly have recorded geomagnetic events (both polarity reversals and excursions). However, the fidelity of the rapid paleomagnetic field oscillations during a polarity reversal remains uncertain. To test the reliability and consistency of the natural remanent magnetization records in Chinese loess, 10 subsets of parallel samples across the Matuyama‐Brunhes (MB) reversal boundary were obtained from the Luochuan region in the hinterland of the Chinese Loess Plateau. Our paleomagnetic results show diversified virtual geomagnetic poles (VGPs) during the MB transition but consistent VGPs outside of the transitional zone. The anisotropy of magnetic susceptibility and rock magnetism results indicate that the sampled interval is rather uniform and undisturbed. The discrepancies of the characteristic remanent magnetization within the MB transition are probably due to the low efficiency in aligning magnetic grains, mainly pseudo‐single‐domain magnetite, associated with the low field intensity. Nevertheless, the stratigraphic location of the MB boundary can be confidently defined. Therefore, we conclude that Chinese loess‐paleosol sequences can record geomagnetic reversal events, but the morphology within the polarity transition is rather questionable.