Age model and susceptibility of sediment core PS2212-3

Palaeomagnetic investigations of two sediment cores recovered from RV Polarstern near the eastern slope of the Yermak Plateau (sites PS1533 and PS2212) reveal convincing evidence for four polarity events of the Earth's magnetic field during the last 170 Ka. A comprehensive rock magnetic study of the sediments proved that fine-grained magnetite is the principal carrier of the remanent magnetization. No changes in magneto-mineralogy across the polarity transitions in the sediments investigated were found. Calcareous nannofossil biostratigraphy, AMS-14C (accelerated mass spectrometry) and oxygen isotope data, and 10Be and 230Th stratigraphies yielded age ranges of 24-29 Ka for the Mono Lake event, 34-43 Ka for the Laschamp event, 72-86 Ka for the Norwegian-Greenland Sea event and 118-128 Ka for the Blake event. Two reverse polarity samples at the base of core PS2212-3 KAL are interpreted as the termination of the Biwa I event (171-181 Ka). the events exhibit full inversion of inclination in both cores. the data suggest that the transition process of the Earth's magnetic field during such polarity events requires some 1 Ka.

对“极地星号”（RV Polarstern）科考船在叶尔马克高原（Yermak Plateau）东坡附近获取的两个沉积岩芯（站位PS1533与PS2212）开展的古地磁研究，获得了确凿证据，证实地球磁场在过去170 ka间存在四次极性事件。针对沉积物开展的全面岩石磁学研究表明，细粒磁铁矿是剩余磁化强度的主要载体。在所研究的沉积物中，未发现极性转换过程中磁矿物学特征发生改变的迹象。钙质超微化石生物地层学、AMS-¹⁴C（加速器质谱法，accelerated mass spectrometry）、氧同位素数据，以及¹⁰Be与²³⁰Th地层序列，分别限定了各极性事件的年龄范围：莫诺湖事件（Mono Lake event）为24~29 ka，拉斯尚普事件（Laschamp event）为34~43 ka，挪威海-格陵兰海事件（Norwegian-Greenland Sea event）为72~86 ka，布莱克事件（Blake event）为118~128 ka。岩芯PS2212-3 KAL底部的两个反向极性样品，被解读为琵琶湖I事件（Biwa I event）的终止阶段（年龄区间171~181 ka）。上述四次极性事件在两个岩芯中均呈现出倾角完全倒转的特征。相关数据显示，此类极性事件期间地球磁场的转换过程耗时约1 ka。