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

Luo, Xin; Liu, Jiabo; Wang, Huapei; Schanner, Maximilian; Zhang, Yuan; Xie, Peng; Tang, Jigen; Han, Peng; Li, Quan; Han, Fei; Chen, Xiaowei; Wen, Chen; Zhong, Wen; Hu, Yufan; Liu, Qingsong

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. Plain Language Summary: The possible existence of a geomagnetic field low‐intensity anomaly in the West Pacific region has been suggested based on the observation of polar lights recorded in Korean historical texts. However, this hypothesis remains controversial due to the lack of paleointensity data. In this study, we performed detailed paleointensity analyses on pottery shards unearthed from the Xiaojiaoshan site in southern China, dating back approximately 6,000 years. Our new paleointensity results, ranging from 14.1 to 26.4 μT (20.7 ± 4.4 μT), are substantially lower compared to the present‐day intensity of 45.8 μT at the study site. These results are also significantly lower than the paleointensity data from surrounding areas in the archeointensity database. By combining our findings with other global archeomagnetic data, we updated the paleomagnetic model ArchKalmag14k. The updated model clearly shows a low‐intensity feature in the West Pacific region around 6,000 years ago. This finding provides new constraints on archeomagnetic reference curves and regional geomagnetic models in East Asia, and likely indicates the presence of a geomagnetic field anomaly. Key Points: Pottery shards from southern China, dated to 6,000 years ago, recorded paleointensity values ranging from 14.1 to 26.4 μT (20.7 ± 4.4 μT)These low paleointensities suggest an anomalous geomagnetic field behaviorThe findings indicate the West Pacific Anomaly likely recurred in Southeast Asia 6,000 years ago

GEOMAGNETISM; AURORAS; MAGNETIC anomalies; EIGHTEENTH century; DATABASES

Geophysical Research Letters, 2025, Vol 52, Issue 9, p1

0094-8276

Academic Journal

10.1029/2024GL113552