Abstract

New petrogeochemical data and the first results of U–Pb dating of detrital zircons from terrigenous units of the Nyarovei series, which refers to the basal level of the Meso–Neoproterozoic sections of the Polar Urals, are presented. On the basis of the analysis of the contents of petrochemical components, rare (Th, Co, Sc, Cr, and V) and rare earth elements in the rocks, and their ratios, it is suggested that sedimentary-volcanogenic rocks of the Nyarovey series were formed within rift-related settings. A possible provenance of detrital material is reconstructed. On the basis of U–Pb isotope-geochronological data, the accumulation time of the Nyarovey deposits is established. It is shown that the entire section of the series, including the Verhnekharbey and the Miniseyshor formations, was formed in the Neoproterozoic; therefore, the widely accepted idea that these units belong to the Mesoproterozoic is erroneous. On the basis of the analysis of data on the age constraints of the Precambrian units from different parts of the Timan–Northern Ural region, the following conclusion is made: contrary to the Southern Urals where the Precambrian section is complete, the post-Paleoproterozoic Precambrian section in the studied region begins with sediments referring to the Meso–Neoproterozoic boundary, but most likely Neoproterozoic ones. This indicates that the Timan passive margin formed in the Neoproterozoic.

中文翻译：

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极地乌拉尔上元古生界碎屑锆石的物源和U–Pb年龄：关于Timan被动裕度形成时间的问题

摘要

介绍了新的岩石化学数据和来自Nyarovei系列陆源单元碎屑锆石的U–Pb测年的初步结果，这是指极地乌拉尔中细新生代剖面的基础水平。在分析岩石中岩石化学成分，稀有元素（Th，Co，Sc，Cr和V）和稀土元素的含量及其比例的基础上，提出了Nyarovey系列沉积-火山成岩是在与裂谷有关的环境中形成的。重建了可能的碎屑物源。根据U–Pb同位素-年代学数据，确定了Nyarovey矿床的沉积时间。结果表明，该系列的整个部分，包括Verhnekharbey和Miniseyshor地层，都是在新元古代形成的。因此，这些单元属于中元古代的广泛接受的想法是错误的。在对来自Timan-North Ural地区不同地区的前寒武纪单元的年龄限制数据进行分析的基础上，得出以下结论：与古前生代前寒武纪完整的前寒武纪断层的南乌拉尔相反。研究区域的剖面以沉积物为准，以中新元古代界为起点，但最有可能是新元古代界。这表明在新元古代形成了Timan被动边缘。与前寒武纪剖面完整的南部乌拉尔山脉相反，研究区的后古生代前寒武纪剖面始于涉及中新元古代界的沉积物，但最有可能是新元古代的沉积物。这表明在新元古代形成了Timan被动边缘。与前寒武纪剖面完整的南部乌拉尔山脉相反，研究区的后古生代前寒武纪剖面始于涉及中新元古代界的沉积物，但最有可能是新元古代的沉积物。这表明在新元古代形成了Timan被动边缘。