Geomagnetic paleointensity and its geodynamic significance for the last 40 ka recorded in the northwestern sub-sea basin of the South China Sea

• Main Authors: Wang HaoSen, Xu Xing, Liu QingSong, Zhong Yi, Chen Ting, Qiang XiaoKe, Chou YuMin, Yang XiaoQiang
• Format: Report
• Language: English
• Published: SCIENCE PRESS 2020
• Subjects: Northwestern sub-sea basin of the South China Sea; Relative paleointensity; Non-dipole field; Geodynamics; East Asian positive magnetic anomaly; NON-DIPOLE; FIELD; KYR; INTENSITY; REVERSAL; ATLANTIC; BE-10; MAP; Geochemistry & Geophysics; Okhotsk; okhotsk sea
• Online Access: http://ir.ieecas.cn/handle/361006/15088; https://doi.org/10.6038/cjg2020N0353

Marine sediments can record relatively continuous paleomagnetic information. Normalized natural remanent magnetization (NRM) records of sediments can be used to construct continuous relative paleointensity (RPI) information of the paleomagnetic field, which facilitates studying evolution of the geomagnetic field and global record correlations. This paper investigated the gravity core L07 drilled from the northwestern sub-sea basin of the South China Sea. By using isothermal remanent magnetization (IRM) as the normalization parameter, RPI curve was constructed for the past 37 ka. Results show that the dominant magnetic minerals in the L07 are mainly (pseudo) single domain (PSD/SD) magnetite particles. In addition, RPI value maximized at 11. 5 ka. By further combining the RPI records of the Okhotsk sea core in East Asia and the abundance changes of Be-10 in China Loess, we attribute the RPI peak to the Earth's non-dipole field. Our results indicate that the influence of positive magnetic anomalies in East Asia can reach to low latitude area such as the South China Sea. This greatly improves our understanding the evolution of magnetic fields in East Asia and provides a possible mechanism for change in the millennium scale's RPI characteristics in this region.