Abstract

The new data on the tectonic setting and conditions for the Middle‒Late Cambrian deposits formation in the southern part of the North Kara terrane, presented in our research, the data induced from the studies of clastic rocks in the metaterrigenous basement complexes of Troynoy Island (Izvestia CEC archipelago) and the northern part of Bolshevik Island (Severnaya Zemlya archipelago). The sandstones of both regions are similar in the lithic wacke composition and contain the same groups of rocks fragments. Detrital zircons and Cr-spinels from sandstones of both regions have the same Zr/Hf and TiO2/Al2O3 ratios, respectively. The similarity of even-aged sediments from both regions can be explained by their accumulation due to the demolition of detrital material from a single source eroded area, which is a segment of the accretionary uplift of the Timan‒Severnaya Zemlya orogenic belt, with the newly formed continental Neoproterozoic‒Cambrian crust. Low- and medium-grade metamorphosed terrigeneous complexes dominated in the structure of the source area. Presence of volcanic and intrusive complexes in the source area is marked by clastic Cr-spinels with geochemical signatures of volcanic arc and suprasubductional ophiolites origin. By the beginning of the Ordovician, the Middle‒Late Cambrian sediments were also crushed, metamorphosed and included in the structure of the Timan‒Severnaya Zemlya orogenic belt. Peculiarities of petrographic and grain-size composition and sorting of the sandstones from the north of Bolshevik Island are more typical for the sediments of gravity turbidite flows, in deep or relatively deep water conditions. The deposits of Troynoy Island could be formed at the shallow and coastal-marine environments.

中文翻译：

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布尔什维克岛和特罗诺伊岛（俄罗斯北极）中上寒武统沉积物的构造环境：以变质岩复合体碎屑岩为例

摘要

我们的研究提供了有关北卡拉地层南部中晚期寒武纪沉积形成的构造环境和条件的新数据，这些数据是由Troynoy岛的变质基底复合物中的碎屑岩研究引起的（ Izvestia CEC群岛）和布尔什维克岛的北部（Severnaya Zemlya群岛）。这两个地区的砂岩在岩性瓦奇成分中相似，并且包含相同的岩石碎屑组。来自两个地区的砂岩的碎屑锆石和Cr-尖晶石分别具有相同的Zr / Hf和TiO2 / Al2O3比。来自两个地区的均匀老化沉积物的相似性可以用它们的积累来解释，这是由于从单一来源侵蚀区拆除了碎屑物质，这是Timan‒Severnaya Zemlya造山带增生隆起的一部分，其中有新近形成的陆陆新元古代o寒武纪地壳。中低品位的变质陆源复合体在源区结构中占主导地位。源区中火山和侵入性复合体的存在以碎屑状Cr尖晶石为标志，这些碎屑Cr尖晶石具有火山弧和超俯冲蛇绿岩起源的地球化学特征。到奥陶纪开始时，中晚期寒武纪沉积物也被压碎，变质，并包含在Timan‒Severnaya Zemlya造山带的结构中。布尔什维克岛北部岩石学和粒度组成的特殊性以及砂岩的分选对于深水或相对深水条件下重力浊流的沉积物更为典型。