Abstract

The soils of Russian Altai highlands were used as a paleoenvironmental archive, as a source of dating material, and as a chronostratigraphic marker to describe Holocene environmental change in the studied area. Based on calibration intervals of 14C dates obtained for buried humus horizons (11 buried soils in 6 studied soil-sedimentary sequences) and some dates from pendants of contemporary soils, following stages of pedogenesis were recorded in studied soil-sedimentary systems and surface soils: 6.4 – 11.5 ky cal BP; about 4.9-5.3 cal BP; 2.5-3.8 cal BP; 0.6 – 1.2 cal BP. All studied surface soils in the basins nowadays develop in cold, ultra-continental water deficit conditions: Skeletic Kastanozems Cambic, Skeletic Cambisols Protocalcic, Skeletic Cambic Calcisol Yermic. The most extreme conditions of soil formation within Holocene were within the last 1-2 kyr. All buried soils were formed in better conditions, more balanced in water, with higher biological activity, mostly within steppe or forest-steppe landscapes. Cryogenic features had been insisting all over the Holocene till nowadays. Water demandant cryogenic features are met in buried soils up to the age of 1-2 ky cal BP. In the last millennia cryogenic processes are suppressed, water demandant features gave way to those which can be formed in contemporary water deficit conditions: simple fissures, frost sorting, and shattering. At lower levels (Kuraj basin) more or less arid cold steppe conditions insisted within the most part of Holocene. Initial stages of soil formation were often ground water affected, or at least shortly waterlogged. At the highest positions humid and relatively warm Early Holocene stage of forest pedogenesis is recorded for the beginning of Holocene, and a Late Holocene (last 3-4 kyr) cold humid phase, presumably under mountain tundra and/or alpines. Microsedimentary intra-soil record in carbonatehumus pendants imprints fine fluctuations of soil water regime at initial stages of soil formation, controlled by local topography, and climatic changes in the second half of Holocene. General trends of environmental changes in the region recorded in soil and soil sedimentary systems are in well correspondence with other records of paleonvironment.

Highlights

  • IntroductionPaleoenvironmental changes in the Russian Altai in the end of the Late Pleistocene and Holocene have been studied using different proxy records and indicators, such as pollen, diatoms, and chironomids in lake sediments, landforms and lithostratigraphy of glacial, lacustrine, and fluvial deposits (Butvilovskij 1993; Rudoy and Baker 1993; Westover et al 2006; Blyakharchuk et al 2007; Ilyashuk and Ilyashuk 2007; Carling et al 2011; Nazarov et al 2012; Agatova et al 2012, 2015 and many others)

  • The upper part of the soil profile (0–40 cm) in all studied surface soils is subdivided into brown A, rather high in organic carbon due to numerous fine plant residues, and Despite location within permafrostaffected area and severe temperature regime, such highly water-demanding cryogenic features as wedges and tongues at horizon borders, material mixed by cryoturbation, disrupted soil horizons, involutions, organic intrusions, frost heave usually are very rare if any in both in polygenetic whole Holocene cryoarid sur

  • As can be seen from the above, all studied buried soils were formed at milder environmental conditions, and less water deficit comparatively to surface contemporary soils, in a more favourable environment for intra-soil biological activity

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Summary

Introduction

Paleoenvironmental changes in the Russian Altai in the end of the Late Pleistocene and Holocene have been studied using different proxy records and indicators, such as pollen, diatoms, and chironomids in lake sediments, landforms and lithostratigraphy of glacial, lacustrine, and fluvial deposits (Butvilovskij 1993; Rudoy and Baker 1993; Westover et al 2006; Blyakharchuk et al 2007; Ilyashuk and Ilyashuk 2007; Carling et al 2011; Nazarov et al 2012; Agatova et al 2012, 2015 and many others). Soils, being environmental archive with high space-resolution (Targulian and Goryachkin 2008) (in comparison with sedimentary records which can have high time resolution at nearly always low space resolution) have certain preferences in paleoenvironmental reconstructions, especially in the areas with high spatial variability of environments. The oldest dates obtained from buried and surface polygenetic soils could be regarded as a low limit of subaerial phase and soil formation

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