Catena 112 (2014) 99–111 Contents lists available at ScienceDirect Catena journal homepage: www.elsevier.com/locate/catena Late Pleistocene–Holocene environmental changes in ultra-continental subarid permafrost-affected landscapes of the Terekhol' Basin, South Siberia Maria Bronnikova a,⁎, Andrey Panin b, Ol'ga Uspenskaya c, Yuliya Fuzeina b, Irina Turova a a Institute of Geography, Russian Academy of Sciences, 119017, Staromonetnyj, 29, Moscow, Russia b Faculty of Geography, Moscow State University, 119992, Vorobjevy Gory, Moscow, Russia c Institute of Horticulture, Russian Academy of Agriculture, 140153, Moscow region, p/o Vereya, Building 500, Russia article info abstract Keywords: This study is an attempt to use closely related inter-complementary paleo-archives of a local landscape to access Paleo-archives understanding of Late Pleistocene–Holocene environmental changes in the region. The study site is a small Paleosols intermountain basin in the Sayan-Tuva Upland, 51°N., 97°E., 1300 m a.s.l. Paleo-archives covering about Paleoenvironment 13,000 yrs were studied: paleosol-sedimentary sequences on a delta-alluvial fan of a small river, lacustrine sedi- Pleistocene/Holocene transition ments in bottom cores and on palsa-islands and soils of palsa-islands. The following sequence of environmental Holocene changes was established. The fluvial activity in the basin reached its maximum at the end of the Late Pleistocene. South Siberia The sharp decrease of the fluvial activity is terminated by two successive paleosols of Pleistocene–Holocene tran- sition. The older paleosol indicates meadow-steppe (or tundra-steppe) conditions with a shallow permafrost table and impeded drainage. The younger paleosol testifies on sharp aridization, biological activity suppression, contrasting water regime, and warming. Dammed lake appeared in the midst of the trough about 11,000 cal yr BP. Sedimentation on delta-alluvial fan was fairly inconsiderable in Holocene. The first part of Holocene (before 4000 cal yr BP) was most balanced in annual distribution of precipitation. Runoff, even being prominently enhanced in a fluvial and relatively warm sub-phase 8000–6250 cal yr BP, was canalized, without giving seasonal floods. Sub-phase 6250–3800 is characterized by increased continentality and relative aridization caused reduc- tion of runoff, lowering of the lake level, and enhancement of cryogenic processes. The next phase 3800–2000 cal yr BP was more humid. It caused slight revival of fluvial processes and rise of lake level. The last 2000 years climate was more continental and the most arid within the studied period. The lake level and runoff values dropped again, and fluvial activity totally decreased. In contemporary soils aridization is reflected in widely spread Natric features and progressive salinization. © 2013 Elsevier B.V. All rights reserved. 1. Introduction to dynamism of fluvial, lacustrine, slope sedimentation (interchanging intensive sedimentation and relatively continuous hiatuses) during Environmental changes and related evolution of soils in the late Late Pleistocene and Holocene. Pleistocene and the Holocene in South Siberia have not been studied There are only few studies on Holocene soil and environmental satisfactory yet as far as the region is complicated and diverse in respect evolution based on the analysis of soil (or soil-sedimentary) records to landscapes and soils, and hardly reachable in some parts. Soils and of the South Siberia (Dergacheva et al., 2006; Desjatkin, 1984, 2008; pedosedimentary sequences of small intermountain basins of the South Vorob'eva, 2010). Some of these studies analyze local sources not Siberia are one of still insufficiently developed and highly promising correlating them with earlier produced data on environmental changes archives of the Late Pleistocene and Holocene environmental changes. in a wider region or the data obtained from other environmental Advantages of soil-sedimentary sequences for paleoenvironmental archives. reconstructions in small inter-mountain basins were closely discussed Studies of different sedimentary Late Pleistocene and Holocene by Vorob'eva (2010).Surfacesoilsofsuchbasins,asarule,havegot archives in the South Siberia and, taking a broader region, in arid sector obvious evidences of polygenesis (recording more than one set of soil of Central Asia are more in number (Blyakharchuk et al., 2004, 2007, forming environmental conditions). Buried soils related to different pe- 2008; Huang et al., 2009; Rudaya et al., 2009; Schwanghart et al., riods and environments are widespread in intrermountain basins due 2009; Vipper et al., 1976 and others). However the data on Late Glacial and Holocene obtained for different localities and applying different ⁎ Corresponding author. Tel.: +7 495 959 00 28; fax: +7 095 959 00 33. methods are often contradictory. Generalizations of data accumulated E-mail address: [email protected] (M. Bronnikova). at the moment are still rare (Blyakharchuk et al., 2004; Zhao et al., 0341-8162/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.catena.2013.08.020 100 M. Bronnikova et al. / Catena 112 (2014) 99–111 2009). Despite the growth in understanding of the Late Glacial and Continuous relic permafrost is found in the bottom of Terekhol' Basin. Holocene climate in the South Siberia and generally in arid/subarid It is up to 170 m thick according to geophysical data (Koshurnikov et al., parts of Asia a further work is needed. In editorial to the special issue 2008). Active layer is 120–300 cm deep in July–August in well drained of Quaternary International “Holocene climate variability in arid Asia: conditions. In most of sections it varies around 200 cm. Nature and mechanisms” necessity to extend a net of study sites across Steppe landscapes prevail in the basin's bottom. They occupy all the region was emphasized, in order to escape difficulties in the identi- areas with the exception of the alluvial–lacustrine–thermokarst fication of regional patterns. Studies focused on climatically sensitive area surrounding the Terekhol' Lake and narrow strips of larch areas (such as ultracontinental arid permafrost affected areas) and taiga along transit streams. The never plowed areas are now inter-archive comparisons are among first-priority tasks (Chen et al., occupied by dry steppe communities (Stipa sp., Psathyrostachys 2009). hyalantha (Rupr.) Tzvel., Poa argunensis Roshev., Bupleurum Usually there are a number of paleoenvironmental archives available scorzonerifolium Willd., Veronica incana L., and Orostachys spinosa in local landscapes to access information on environmental changes. (L.) C.A. Mey) and communities of meadow steppes (Stipa sp., Bromopsis There could be independent sedimentary records of various origins (fluvi- inermis (Leyss.) Holub., Potentilla bifurca, P. argunensis Roshev., al, limnic sediments, loess, peat etc.) and soil record in polygenetic surface Thermopsis mongolica Czefr., Heteropappus altaicus (Willd.) Novopokr., soils and buried paleosols (soil memory). Different kinds of paleo- and B. scorzonerifolium Willd). Previously arable lands have lost Stipa archives in most cases are studied independently because of narrow sp. and got some ruderal species such as P. hyalantha (Rupr.) Tzvel., specialization of researchers and common difficulties of interdisciplinary Elytrigia repens (L.) Nevski, Potentilla tanacetifolia Willd. ex Schlecht., studies. Meanwhile each kind of paleo-archive each method used to Artemisia glauca Pall. ex Willd., Chenopodium album L., Descurainia extract paleoecological information has its own approaches, limitations, sophia L. Larch taiga communities cover mountain slopes of the basin. advantages and disadvantages. Therefore a comparative study of different Lake terraces and low islands are occupied mostly by meadows and sedimentary and paleosol archives in a single local geosystem seems to be meadow-steppes, the highest positions of the terraces and high islands the most fruitful and reliable for environmental reconstructions. Data are covered with normal steppe vegetation with Stipa sp. obtained from independent environmental archives of the same age are Cryosols are the major and the most widely spread soils of the complementary and verifying each other. Meanwhile such comparative Terekhol' Basin. Soil cover of steppe landscapes, particularly the sur- studies of different local paleoenvironmental archives are not a common face of the delta-alluvial fan, mostly consists of Turbi-Natri-(Sali)- practice in paleopedology. Only some rare studies can be cited in this field Molliglossi-Calcic Cryosols and Turbi-Protonatri-Molliglossi-Calcic (Sedov et al., 2003, 2009, 2010; Solleiro-Rebolledo et al., 2006). Cryosols. There are two general options of surface soil formation This study is an attempt to use closely related complementary paleo- which proceeds at the background of numerous evidences of archives of a local landscape – asmallintermountainbasin– for most cryogenesis: (1) all the variety of solonization–solodization and comprehensive understanding of Late Pleistocene–Holocene environ- alkalization–dealkalization processes in its different stages (from mental changes in the region. The following archives were studied its initial phase through the mature, sodic stage and later secondary as sources of paleoenvironmental information: salinization up to residual morphological features of Natric horizon), and (2) chernozemic process including formation of the Mollic hori- - soil-sedimentary