Lithological and geomorphological indicators of glacial genesis in the upper Quaternary strata, Nadym River basin, Western Siberia

Oleg Sizov,Anatoly Molodkov,Evgeny Abakumov,Anna Volvakh,Andrey Vishnevskiy,Andrey Soromotin

doi:10.5194/se-11-2047-2020

Abstract

Abstract. Analysing the genesis of Quaternary sediments is important for understanding the glaciation history and development of marine sediments in the northern part of Western Siberia. The problem is relevant since there is no consistent concept of the Quaternary sediment genesis in the north of Western Siberia. The formation of sediments is associated with marine, glacial and interglacial sedimentation conditions. The research objective is to identify the persistent features characterising the conditions of sedimentation and relief formation using the Nadym River basin as an example. The best method for studying this problem is a comprehensive analysis of the lithological, chronostratigraphic, petrographic and geomorphological studies of the Quaternary sediment upper strata. This study provides data from the analysis of the basic characteristics of quartz grains at the site. The rounding and morphology of the quartz grains provide evidence of possible glacial processing of some of the site strata. A petrographic study of selected boulder samples was performed. Some of them, by the shape and presence of striation, can be attributed to ice basins. The first use of a detailed digital elevation model applied to the study area made it possible to identify specific relief forms that could very likely be created during glaciations. Based on the analysis, we propose to consider the vast lake alluvial plains in the Nadym River basin as periglacial regions. This idea lays the lithological framework for understanding the reasons for the formation of the modern landscape structure. The materials and descriptions provided are of interest to researchers of Quaternary sediments, topography, vegetation and soil cover, particularly researchers engaged in revising the history of the natural environment development in the north of Western Siberia.

Highlights

The history of geomorphological development in the northern part of Western Siberia was a subject of intensive discussion at the end of the 20th century
Sections K-1 and NS-6 show the similar structure of the second above-ground terrace of the Nadym and Tanlov rivers: in the upper part, thick podzolised soil is formed over the aeolian deposits, in the middle part, floodplain-type deposits dominate, and in the lower part they are replaced by wellleached grey layered sand
The middle part of the section is dominated by fine- and medium-grained sand; the portion of large fractions increases in the lower part where single pebbles of up to 3–4 cm are found

Summary

Introduction

The history of geomorphological development in the northern part of Western Siberia was a subject of intensive discussion at the end of the 20th century. The stratigraphy of the Yenisey River estuary is a key factor of the Western Siberian lowland Quaternary evolution. Numerous examples of sedimentation alternation induced by various cover glaciations of different ages and thicknesses are presented. This series of sediments was used as a background for geological interpretation of the history of the Western Siberian lowland. The possible existence of ice sheets and related permafrost sediments was identified as a key issue at the beginning of the systematic geological study of the north of Western Siberia in the 1960s. Svendsen et al, 2004) suggested that there were extensive glaciations that resulted in blocking the Yenisei, Pur, Taz and Nadym rivers at certain stages, leading to the formation of large glacier dammed lakes (Grosvald, 1999) Some researchers (e.g. Svendsen et al, 2004) suggested that there were extensive glaciations that resulted in blocking the Yenisei, Pur, Taz and Nadym rivers at certain stages, leading to the formation of large glacier dammed lakes (Grosvald, 1999)

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Conclusion