Low Geomagnetic Field Intensity in Southern China 6,000 Years Ago

Abstract

The West Pacific Anomaly (WPA), a low geomagnetic field anomaly observed in the 16th to 18th centuries, represents a recently recognized and complex feature of Earth's magnetic field. However, the history of the WPA is still uncertain due to a scarcity of paleointensity data in Southeast Asia. Here, we conducted archeointensity analyses on pottery shards from the Xiajiaoshan site in southern China, dated to 4107 ± 123 BCE. Using Thellier–Coe and Repeated Thellier-Series Experiment methods, we obtained high-fidelity paleointensities ranging from 14.1 to 26.4 μT (20.7 ± 4.4 μT). These values are significantly lower than surrounding archeointensity data. We incorporated this new data into ArchKalmag14k paleomagnetic field model, which shows the presence of a geomagnetic field low-intensity anomaly in Southeast Asia around 6,000 years ago. Our study provides the first absolute paleointensity data for low-latitude East Asia at that time, suggesting that the WPA may have recurred approximately 6,000 years ago.