Various geodynamo models proposed recently in the different ways explain the processes of geomagnetic field generation and its evolution over the course of the geological history. The testing capabilities of these models are strongly limited, inter alia, by the scarcity of the reliable magnetostratigraphic data for the Paleozoic and more ancient eras of geologic time, especially for the time periods before the establishment of the Kiama and Moyero superchrons. In this work, we present the results of the magnetostratigraphic and geochemical studies of the top part of the Upper Cambrian section in the Chopko river valley, Norilsk region, which is one of the most complete Upper Cambrian reference sections in the Siberian Platform. Our studies have shown that in the Late Cambrian there has been an interval of the reversed magnetic polarity which lasted at least 1.5 million years. Together with the previous data obtained on the Upper Cambrian of the Kulumbe river section and on the Early Ordovician of the Kotuy river (Pavlov and Gallet, 1998; Pavlov et al., 2017), our result presented in this study means that between the mid-Cambrian epoch of the extremely frequent reversals (Gallet et al., 2019) and the Ordovician Moyero superchron of the reversed polarity (Pavlov et al., 2005), there intervened at least two magnetic polarity intervals (reversed and normal) whose duration was at least one million years. This conclusion quite definitely points to a low frequency of the reversals on the eve of the Ordovician superchron and supports the concept according to which a process preparing the onset of the superchron takes place at the core/mantle boundary. The data obtained in our study support the hypothesis of the existence of three geodynamo regimes with sharp, on the order of a few million years, transitions between them (Gallet and Pavlov, 2016). At the same time, overall, the quality and amount of the currently existing magnetostratigraphic data for the pre-Mesozoic and, in particular, for the Paleozoic are still insufficient for confident testing this hypothesis.

中文翻译：

---

乔普科河上寒武统关键段、西西伯利亚地台地磁地层及接近莫耶罗超纪时地磁反转频率的新约束

最近提出的各种地球动力学模型以不同的方式解释了地磁场的产生过程及其在地质历史过程中的演变。这些模型的测试能力受到严重限制，尤其是由于缺乏古生代和更古老地质时代的可靠磁地层数据，特别是在 Kiama 和 Moyero 超年代学建立之前的时期。在这项工作中，我们展示了诺里尔斯克地区乔普科河谷上寒武统剖面顶部的磁地层学和地球化学研究结果，该剖面是西伯利亚地台上最完整的上寒武统参考剖面之一。我们的研究表明，在晚寒武世，有一段至少持续了 150 万年的反转磁极间隔。结合先前在库伦贝河段上寒武统和科图伊河早奥陶世获得的数据（Pavlov and Gallet，1998；Pavlov et al.，2017），我们在本研究中提出的结果意味着-寒武纪极端频繁的逆转（Gallet et al., 2019）和奥陶纪Moyero superchron（Pavlov et al., 2005），至少干预了两个磁极间隔（反转和正常），其持续时间为至少一百万年。这一结论非常明确地表明奥陶纪超时相前夕的反转频率较低，并支持了在地核/地幔边界处发生准备超时相开始的过程的概念。在我们的研究中获得的数据支持存在三个地球发电机制度的假设，它们之间的过渡急剧，大约几百万年（Gallet 和 Pavlov，2016 年）。同时，总体而言，现有的前中生代特别是古生代磁地层数据的质量和数量仍然不足以自信地检验这一假设。在几百万年的时间里，它们之间会发生转变（Gallet 和 Pavlov，2016 年）。同时，总体而言，现有的前中生代特别是古生代磁地层数据的质量和数量仍然不足以自信地检验这一假设。在几百万年的时间里，它们之间会发生转变（Gallet 和 Pavlov，2016 年）。同时，总体而言，现有的前中生代特别是古生代磁地层数据的质量和数量仍然不足以自信地检验这一假设。