A full-vector paleomagnetic record from the southern South China sea reveals regional geomagnetic instability over the past 30,000 years

Abstract

The Western Pacific Anomaly (WPA), a low-intensity geomagnetic anomaly associated with complex geodynamic processes, remains poorly understood due to the limited availability of paleomagnetic records from the region. Here, we present a high-resolution full-vector paleomagnetic record from core BKAS58PC in the southern South China Sea, spanning the past 30,000 years and filling a critical gap in Late Pleistocene geomagnetic records from the equatorial western Pacific. The directional data reveal multiple large-amplitude geomagnetic directional swings between 30 and 10 ka, reflecting axial dipole instability during the post–Mono Lake excursion recovery phase. Comparisons with regional and global paleointensity records reveal pronounced differences in behavior, particularly between 30 and 23 ka, indicating enhanced non-dipole activity and possibly the recurring emergence of the WPA. Our findings provide a rare constraint on geomagnetic variability in the equatorial western Pacific and may offer new insights into the Earth's interior dynamics.