Behaviour of the Earth’s magnetic field during superchrons: comparative study of the Cretaceous and Meso-Neoproterozoic Maya events recorded in the flows of the Okhotsk- Chukotka Volcanic Belt (NE Russia) and the sediments of the Yenisey Ridge (SW Siberia

超纪元期间地球磁场的行为：鄂霍次克-楚科奇火山带（俄罗斯东北部）和叶尼塞山脊（西伯利亚西南部）沉积物中记录的白垩纪和中新元古代玛雅事件的比较研究

• 批准号: 405632737
• 负责人: Privatdozent Dr. Florian Lhuillier
• 金额: --
• 依托单位: Sektion Geophysik
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2019
• 资助国家: 德国
• 起止时间: 2018-12-31 至 2021-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/405632737?language=en
• 关键词: Behaviour; Earth; magnetic; field; during

The Earth’s magnetic field, generated by a dynamo process in the outer core, is a dynamic object, the time variability of which, on centennial-to-millenial timescales, is called palaeosecular variation (PSV). On multimillion-year timescales, this field is known to stochastically reverse its polarity, but can surprisingly also produce prolonged periods (> 20 Myr) with stable polarity termed superchrons. These persistently occurring events over the Earth’s history, documented both during the Phanerozoic and Proterozoic, are usually characterised by a strong dipolar field and low directional dispersion. Nevertheless, the possibility of more complex temporal dynamics with periods of higher variability within a superchron, has been recently proposed, and needs to be investigated further. Having a clear view of the behaviour of the geomagnetic field during superchrons, indeed has direct implications on the understanding of the outer core’s dynamics.To this end, we would like to investigate comparatively the behaviour of the Earth’s magnetic field during the Cretaceous Normal Superchron (CNS, 121–83 Ma) and the Meso-Neoproterozoic Maya superchron (PMS, ~1,000 Ma) recorded in the flows of the Okhotsk-Chukotka Volcanic Belt (NE Russia) and the sediments of the Yenisey Ridge (SW Siberia). The project includes two field campaigns in each area to collect a large amount of palaeomagnetic samples. On one hand, the almost unexplored magnetic record of the Okhotsk-Chukotka Belt offers a unique possibility to sample, at the same latitude, piles of volcanic flows from several time intervals within and after the CNS. On the other hand, the carbonate Kartochka formation of the Yenisey Ridge, is a nonpareil location to scrutinise the temporal evolution of the field during and around the PMS, and conduct relative palaeointensity experiments.The primary aim of this project is to produce detailed magnetostratigraphy for the Kartochka formation, and determine directional PSV estimates over various time intervals for the Okhotsk-Chukotka Volcanic Belt. We will pay special attention to the time dependency of the magnetic field to discern possible intermittencies of the geodynamo during the two investigated superchrons. We will also conduct relative (or where possible — absolute) palaeointensity experiments to determine the relative variability in intensity, which is assumed to be a robust and latitude-independent PSV estimator. One secondary method-related aspect of the project will be to better assess the robustness of pseudo-Thellier experiments. Ultimately, our new results will be compared with the existing palaeomagnetic dataset and the predictions from numerical dynamo simulations.

由外核中的发电机过程产生的地球磁场是一个动态对象，即百年至m义务的时间变化，称为古属分类变化（PSV）。已知的牙齿扭转了其极性，但稳定的极性也会产生稳定的超晶状，这持续发生在历史上的偶极场和低方向性的情况下。已经进行了进一步研究，实际上具有外核动力学的直接含义。在白垩纪正常的超级沿着地球的磁场（CNS，121-83 MA）和中氧化元中的磁场上，〜1,000 MA）在Okhotsk-Chukotka火山带（NE俄罗斯）和Yenisey Ridge的沉积物（SW Siberia）中记录下来几乎磁性记录的记录是从CN中和之后的几个时间间隔进行采样DE的Aunique the可能性的可能性。在PMS周围和周围的田地）PALAEEOINSITY用于确定强度的变异性，这被认为是Andetend PSV估计器。