An experimental assessment on the stability of remanent magnetization of Chinese loess and implications for the loess magnetostratigraphy investigations

Magnetostratigraphic dating is an important method for establishing the chronological framework of Chinese loess. However, the positions of geomagnetic polarity boundaries and anomalous geomagnetic excursions have been reported inconsistently across different loess sections. Previous studies have questioned the fidelity of the primary remanent magnetization recorded by coarse loess layers, as it may be influenced by remagnetization processes during subsequent geomagnetic reversals. In this study, we simulated magnetic field reversals in the laboratory to investigate their effect on paleomagnetic records in Middle and Late Pleistocene loess and paleosol samples from the western and southeastern Chinese Loess Plateau (CLP). The results reveal that: 1) Remagnetization processes are more likely to occur in surface subsamples from the same block of loess compared to interior subsamples, while such phenomena are rare in paleosol samples. 2) Individual specimens from the western CLP are more prone to exhibiting anomalous remanent magnetization components, suggesting that coarser and more porous samples are more susceptible to recording erratic paleomagnetic information. 3) Secondary remanent magnetization acquired in the laboratory is unstable and exhibits varied thermal demagnetization behaviors among individual subsamples. These observations suggest that the reliability of short geomagnetic reversals, as well as the transition processes and behaviors recorded in Chinese loess, should be carefully re-evaluated. The effects of remagnetization cannot be ignored when investigating the magnetostratigraphy of Chinese loess.