New archaeointensity results from ~7 ka in Eastern China and their constraint on the regional variations of the geomagnetic field

SUMMARY Archaeomagnetic study serves as an effective way to investigate the detailed variations of the geomagnetic field during the Holocene. China has accumulated numerous high-quality archaeomagnetic data in recent years, but these data are primarily limited to the period younger than 1500 BCE, which limits our comprehensive understanding of the Holocene geomagnetic field evolution. Here, we carried out archaeomagnetic research on 28 unoriented pottery shards and baked clays collected from two Neolithic archaeological sites, with ages spanning from ∼5350 to 5030 BCE, in Anhui province, Eastern China. Rock magnetic analyses show that pseudo-single domain magnetite is the main magnetic carrier among the samples with limited contributions from high coercivity minerals such as hematite. The ideal magnetic behaviour demonstrates the samples are suitable for palaeointensity experiments, as confirmed by the palaeointensity results. A total of 14 samples yielded high-fidelity palaeointensity results, indicating that a fast-changed geomagnetic field with virtual axial dipole moments varying from ∼56 to ∼91 ZAm2 over ∼300 yr. This inference is further evidenced by intensities recovered from the double-remanent components of some samples through vector calculation. Our new data provide reliable anchors for the strength variations of the geomagnetic field in Eastern Asia during the poorly constrained time period before 4000 BCE. With the new data in this study, we updated the previous Chinese archaeointensity reference curve and named the new curve as ArchInt_China3, which extends the previous curve forward for ∼500 yr. The newly reported archaeointensity data and released reference curve in this study will provide valuable insights into the regional and global geomagnetic field variations during the Holocene, and thus assist in understanding the dynamic processes in the Earth's interior.