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Abstract <p>The discovery of Pleistocene paleosols, including the level corresponding to the previous interglacial period (MIS5e), in the north of Western Siberia is of fundamental importance for Quaternary stratigraphy and paleoecology. This paper presents for the first time the results of a study of a pedocomplex that was found in the Belaya Gora section (Vakh River valley). The period of its formation, established through uranium–thorium dating and taking into account paleobotanical and paleontological data, spans from the end of MIS 6 to MIS 4 inclusive. A morphogenetic analysis at the macro-, meso-, and micro-levels, as well as data on granulometry, mineralogy, and humus composition (including the humic acid/fulvic acid ratio and proportions of the main structure-forming elements (C, H, and N) in humic acids), have made it possible to reconstruct the succession of pedogenetic, sedimentary, and cryogenic processes. A paleoecological reconstruction and chronostratigraphic attribution of all pedocomplex levels were carried out based on the resulting comprehensive geological record and using the previously published paleontological data. A paleosol subprofile corresponding to the warmest substage MIS 5e, the Kazantsevo thermochron, has been identified. At the same time, it has been shown that the permafrost–gley (cryohydromorphic) stage, which marks the end of the formation of each paleosol level and took place during the cold substages of MIS5, has a dominant influence on paleosol morphology and masks the features of preceding, warmer phases. The unexpected finding of newly formed gypsum crystals in combination with ferruginous nodules has been explained by the oxidation of previously formed pyrite and has also been attributed to the cryohydromorphic phase of paleopedogenesis. An interregional correlation of the studied profile with pedostratigraphic schemes of the loess formation in adjacent regions (East European Plain and south of West Siberia) has been carried out. Correlative levels have been identified in loess–paleosol sequences for most of the elements of the studied pedocomplex and the overlying sedimentary and cryogenic MIS4 units except the paleosols from the end of MIS6 (Taz cryochron), which indicates a gap in the South Siberian loess–paleosol record.</p>

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Paleosol Record of the Transition MIS5–MIS4 Thermochron in the Belaya Gora Section (Vakh River, Western Siberia)

  • 期刊论文

  • 发表日期：

    2025年12月25日

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  • S. N. Sedov,
  • A. V. Rusakov,
  • V. S. Sheinkman,
  • M. I. Dergacheva,
  • N. L. Bazhina,
  • F. E. Maksimov

摘要

Abstract

The discovery of Pleistocene paleosols, including the level corresponding to the previous interglacial period (MIS5e), in the north of Western Siberia is of fundamental importance for Quaternary stratigraphy and paleoecology. This paper presents for the first time the results of a study of a pedocomplex that was found in the Belaya Gora section (Vakh River valley). The period of its formation, established through uranium–thorium dating and taking into account paleobotanical and paleontological data, spans from the end of MIS 6 to MIS 4 inclusive. A morphogenetic analysis at the macro-, meso-, and micro-levels, as well as data on granulometry, mineralogy, and humus composition (including the humic acid/fulvic acid ratio and proportions of the main structure-forming elements (C, H, and N) in humic acids), have made it possible to reconstruct the succession of pedogenetic, sedimentary, and cryogenic processes. A paleoecological reconstruction and chronostratigraphic attribution of all pedocomplex levels were carried out based on the resulting comprehensive geological record and using the previously published paleontological data. A paleosol subprofile corresponding to the warmest substage MIS 5e, the Kazantsevo thermochron, has been identified. At the same time, it has been shown that the permafrost–gley (cryohydromorphic) stage, which marks the end of the formation of each paleosol level and took place during the cold substages of MIS5, has a dominant influence on paleosol morphology and masks the features of preceding, warmer phases. The unexpected finding of newly formed gypsum crystals in combination with ferruginous nodules has been explained by the oxidation of previously formed pyrite and has also been attributed to the cryohydromorphic phase of paleopedogenesis. An interregional correlation of the studied profile with pedostratigraphic schemes of the loess formation in adjacent regions (East European Plain and south of West Siberia) has been carried out. Correlative levels have been identified in loess–paleosol sequences for most of the elements of the studied pedocomplex and the overlying sedimentary and cryogenic MIS4 units except the paleosols from the end of MIS6 (Taz cryochron), which indicates a gap in the South Siberian loess–paleosol record.