Abstract

The work is based on extensive factual material, including a core collection and GIS data on 84 deep wells drilled in the southeastern Nepa–Botuoba anteclise (Siberian Platform). Lithological studies of the Vendian basal deposits formed in the postglacial epoch were carried out. These deposits characterized by significant vertical lithological heterogeneity include layers of highly radioactive coarse-grained monazite-containing rocks. Therefore, it was necessary to check the clay content and combine the chosen lithological types into paragenetic rock associations that compose relatively thick intervals of the section and can be recognized using the geophysical research methods. The results of cyclostratigraphic analysis made it possible to indentify three ranks of binomial sedimentary cyclites and a basal acyclic unit of pudding conglomerates. The population of detritus zircons from pudding conglomerates (66 grains) contains the youngest grains with an age of 600–900 Ma. Minimum age of zircons is 631 ± 14 Ma. Taking into account the presence of diamictites and pudding conglomerates in the Vendian basal deposits, the results of studying the quartz grain surface and mineralogy of the heavy fraction from the sedimentary cover base and basement rocks suggested that their formation coincided with late glacial and postglacial stages of the Gaskier glacioperiod (584–582 Ma). Structural and textural features of postglacial deposits were determined based on the hydrodynamic parameters of fluvioglacial flows, features of the postglacial relief, the distance to provenances, and the mineral composition of eroded rocks. The Vendian cyclical deposits (Nepa and Tira formations) were formed during climate changes from the glacial to arid conditions in the course of transition from the continental to coastal-marine type.

中文翻译：

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Nepa–Botuoba东南部的文迪斯后冰期相的相和古地理重建

摘要

这项工作基于广泛的事实材料，包括一个核心集合和有关在Nepa–Botuoba东南缘（西伯利亚平台）上钻的84口深井的GIS数据。对冰期后形成的文迪亚基底沉积物进行了岩性研究。这些以明显的垂直岩性非均质性为特征的矿床包括高放射性粗粒含独居石的层。因此，有必要检查粘土含量，并将选定的岩性类型组合到共生岩石组合中，这些组合构成了该段相对较厚的间隔，并且可以使用地球物理研究方法加以识别。旋回地层分析的结果使我们有可能识别出三类二项式沉积环闪石和一个布丁砾岩的基底无环单元。布丁集团的碎屑锆石（66粒）中年龄最小的是600-900 Ma。锆石的最小年龄为631±14 Ma。考虑到文迪亚基底沉积物中存在铁矾土和布丁砾岩，研究石英沉积物表面和沉积盖层基底和基底岩石中重组分的矿物学的结果表明，它们的形成与晚冰期和后冰期相吻合。 Gaskier glacioperiod（584–582 Ma）。冰川期沉积物的结构和质地特征是根据潮河水流的流体力学参数，冰川后起伏特征，到物源的距离以及侵蚀岩石的矿物成分确定的。