Abstract

Sedimentological features of the Upper Cambrian–Middle Ordovician rocks exposed in eastern Taimyr in the Faddey Gulf area are discussed. The studied sections belong to the transitional facies zone located between the carbonate platform (Siberian Platform continuation) in the south and a relatively deep-water basin in the north. The studied deposits compose a genetically coherent sequence formed in the distal zone of the siliciclastic–carbonate ramp at a depth exceeding the storm wave base. The lower (Upper Cambrian–lowermost Ordovician) part of the sequence is represented by limestones, dolomitized carbonate siltstones, and sandstones with shale layers. The upper (Lower–Middle Ordovician) part of the studied interval is dominated by shales with thin layers of carbonate siltstones. The carbonate detritus was sourced from a shallow-water shelf located south of the studied sections. The siliciclastic admixture in carbonate siltstones and sandstones was sourced from an island in the northern part of the modern Siberian Platform. The sandy material was transported by storm bottom currents; the fine-grained particles, by surface currents and winds as particulates and suspension clouds in the bottom water. Carbonate sandstones with the typical turbidite sedimentary structures, common in the lower part of the section, were deposited by turbidity currents initiated by storms. At that time, a prominent break likely existed in the ramp profile. The predominant NE orientation of flute casts indicates the alongslope (or along the trough axis) transport of material by bottom currents. The ramp topography was leveled in the second half of the Early Ordovician and in the Middle Ordovician.

中文翻译：

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碳酸盐台地与黑色页岩盆地过渡带（泰米尔东部）下古生界沉积

摘要

讨论了法代湾地区泰米尔东部出露的上寒武统—中奥陶统岩石的沉积学特征。研究剖面属于位于南部碳酸盐台地（西伯利亚台地延续）与北部较深水盆地之间的过渡相带。所研究的沉积物构成了在超过风暴波底深度的硅质碎屑-碳酸盐斜坡的远端区域形成的遗传连贯序列。该层序的下部（上寒武统—最下部奥陶统）以石灰岩、白云化碳酸盐粉砂岩和具有页岩层的砂岩为代表。所研究层段的上部（下—中奥陶统）以具有薄层碳酸盐粉砂岩的页岩为主。碳酸盐碎屑来自位于研究剖面以南的浅水陆架。碳酸盐粉砂岩和砂岩中的硅质碎屑混合物来自现代西伯利亚地台北部的一个岛屿。沙质物质由风暴底流输送；细粒颗粒，通过地表水流和风作为颗粒和悬浮云在底层水中。具有典型浊积岩沉积结构的碳酸盐砂岩，常见于断面下部，由风暴引发的浊流沉积。当时，坡道剖面中可能存在明显的断裂。长笛铸件的主要 NE 方向表明底流沿斜坡（或沿槽轴）输送材料。