New constraints on the variation of the geomagnetic field during the late Neolithic period: Archaeointensity results from Sichuan, southwestern China

Abstract

We have carried out an archaeomagnetic study on a late Neolithic locality (Liujiazhai) in Sichuan, southwestern China. We pull together various dating techniques, including radiocarbon analysis, optically stimulated luminescence dating, stratigraphic information as well as archaeological and archaeomagnetic estimations, to constrain the age of the studied samples. Rock magnetic results indicate thermally stable fine-grained magnetite or titanomagnetite as the dominant magnetic carriers. More than half of the specimens (141/246) in the paleointensity experiment pass the selection criteria and are considered to record robust intensity values. The virtual axial dipole moments range from approximately (2.8 to 7.8) × 1022Am2 with an average of 5.9 × 1022Am2, indicating that the geomagnetic intensity around 3000 before the Common Era (B.C.E.) is overall lower than the present field intensity (9.8 × 1022Am2) of this area. The new results from Liujiazhai are generally consistent with the published data of similar age but deviate from the only available model of CALS10k.1b at certain time periods, making them important for future improvements of the model. Those data are significant for constraining the variation of geomagnetic field intensity between ∼3100 and 2600 B.C.E. and improving the regional model of eastern Asia.