Persistent Influence of Non‐Dipole Geomagnetic Field on East Asia Over the Past 4,000 Years

Abstract

The observed variations in intense geomagnetic flux lobes have a significant impact on regional geomagnetic fields, and produce unique geomagnetic characteristics. To investigate the time‐dependent effect of the Siberian flux lobe on the geomagnetic field in East Asia, we reconstructed a stacked full‐vector paleomagnetic secular variation record (since 2000 BCE) from three sediment cores collected in the Bohai Sea, China. Age models of the studied cores were established through a combination of radiocarbon 14C dating and inter‐profile correlation of mass‐normalized magnetic susceptibility. Rock magnetic results indicate that fine‐grained magnetite is the primary remanent carrier. We found that the paleomagnetic field records in the Bohai Sea correspond more closely with those from the middle latitudes, rather than the low latitudes. This was primarily attributed to the variation of the Siberian flux lobe. This study provides a better understanding of the contrasting patterns of regional geomagnetic fields in East Asia, and emphasizes the significant role played by the Siberian flux intensity lobe in shaping their formation.