The Late Pleistocene Bokhan site (Fore-Baikal area, Russia) and its palaeoenvironmental reconstruction

Accepted Manuscript The Late Pleistocene Bokhan site (Fore-Baikal area, Russia) and its palaeoenvironmental reconstruction Fedora Khenzykhenova, Kunio Yoshida, Takao Sato, Alexander Shchetnikov, Evgenia Osipova, Guzel Danukalova, Varvara Ivanova, Alexandra Simakova, Ivan Filinov, Elena Semenei, Oyuna Namzalova, Erdem Tumurov, Dmitry Malikov PII:

S1040-6182(18)31028-0

DOI:

https://doi.org/10.1016/j.quaint.2019.04.023

Reference:

JQI 7840

To appear in:

Quaternary International

Received Date: 31 August 2018 Revised Date:

3 February 2019

Accepted Date: 24 April 2019

Please cite this article as: Khenzykhenova, F., Yoshida, K., Sato, T., Shchetnikov, A., Osipova, E., Danukalova, G., Ivanova, V., Simakova, A., Filinov, I., Semenei, E., Namzalova, O., Tumurov, E., Malikov, D., The Late Pleistocene Bokhan site (Fore-Baikal area, Russia) and its palaeoenvironmental reconstruction, Quaternary International (2019), doi: https://doi.org/10.1016/j.quaint.2019.04.023. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT

The Late Pleistocene Bokhan Site (Fore-Baikal Area, Russia) and its palaeoenvironmental reconstruction Fedora Khenzykhenovaa*, Kunio Yoshidab, Takao Satoc, Alexander Shchetnikovd,e,f, Evgenia Osipovag, Guzel Danukalovag,j, Varvara Ivanovae,h, Alexandra Simakovai, Ivan Filinovd,e,f, Elena

Geological Institute, Siberian Branch (SB), Russian Academy of Sciences (RAS), Ulan-Ude,

Russia b

Keio University, Japan

d e f

Institute of the Earth’s Crust, SB RAS, Irkutsk, Russia

Vinogradov Institute of Geochemistry, SB RAS, Irkutsk, Russia

M AN U

c

University Museum, Tokyo University, Tokyo, Japan

SC

a

RI PT

Semeneik, Oyuna Namzalovaa, Erdem Tumurovk, and Dmitry Malikovl

Irkutsk Scientific Centre, SB RAS, Irkutsk, Russia

g

Institute of Geology, Ufa Federal Research Centre RAS, Ufa, Russia

h

Institute of Geology and Mineral Resources of the Ocean (VNIIOkeangeologia), St. Petersburg,

Russia

Geological Institute, RAS, Moscow, Russia

j

Kazan Federal University, Kazan, Russia

k l

TE D

i

A.P. Ershov Institute of information systems, SB RAS, Novosibirsk, Russia

Sobolev Institute of Geology and Mineralogy, SB RAS, Novosibirsk, Russia

EP

*Corresponding author: Geological Institute, Siberian Branch (SB), Russian Academy of

AC C

Sciences (RAS), 6a Sakhjanovoi str., 670047, Ulan-Ude, Russia.

E-mail addresses: [email protected] (F. Khenzykhenova), [email protected] (K. Yoshida); [email protected] (T. Sato); [email protected] (A. Shchetnikov), [email protected] (E. Osipova); [email protected] (G. Danukalova), [email protected] (V. Ivanova), [email protected] (A. Simakova), [email protected], [email protected] (E. Semenei); [email protected] (O. Namzalova), [email protected] (E. Tumurov); [email protected] (D. Malikov)

Abstract

ACCEPTED MANUSCRIPT

Multidisciplinary research was carried out at the new Late Pleistocene Bokhan site in the Baikal region (Fore-Baikal) including geochemical and petrochemical X-ray fractions, palynological and palaeozoological studies, and AMS-dating. Four palynological complexes show a development of vegetation from open meadow-steppe landscapes that are replaced by meadow steppe with small areas of tundra vegetation to pine and pine-birch boreal forests. The fauna included molluscs, reptile and mammals of tundra, steppe and taiga inhabitants. It is a so-called

RI PT

no-analogue fauna extant analogy of species composition which reflects tundra-steppe landscapes in conditions of cold and dry climate during Sartanian time (MIS 2) (layers 1-2) and tundra-forest-steppe landscapes with more comfortable climatic conditions, during the end of

SC

The Pleistocene (layer 3).

M AN U

Keywords: molluscs, reptile, mammals, Late Pleistocene, Fore-Baikal, no-analogue fauna

1. Introduction

The Bokhan section (coordinates 53°10'7.08"N, 103°48'23.88"E; altitude 490 m above sea level), is located on the territory of the Fore-Baikal sector of the Middle Siberian Plateau within the Irkutsk-Cheremkhovo Hilly Plain on the slope of the Ida River valley (right tributary of the

TE D

Angara River) (Fig. 1). The relief of the territory is characterized by wide flattened interfluves, in the upper belt of which the relics of the Cretaceous-Paleogene surface of the levelling dominate. The modern river network is embedded in this hilly plain. The indigenous rocks of the territory are represented by burgundy and brown (red) dolomites and limestones of the Angara

developed.

EP

suite of the Lower Cambrian, over which the weathering crust of the Paleogene-Neogene age is

AC C

Despite the surroundings of the Baikal Lake are known for their famous Late Palaeolithic archaeological sites – Malta, Byret’, Achinskaya and others (Gerasimov, 1931; Medvedev et al., 2001 etc.), well stratified, dated and studied in detail by complex of methods Pleistocene sites are not numerous in this area. Biostratigraphical field investigations of the Pleistocene deposits of this area conducted by geologists and palaeontologists in cooperation with archaeologists permit to discover new localities which studies allow to add a new information to the palaeonvironment evolution of the Baikal area during Quaternary. One of the recently studied sites is the Bokhan site which was discovered in 2012. A joint Russian-Japanese study of the stratigraphical sequence performed in 2012-2017 in the vicinity of the Bokhan settlement allowed the obtainment of representative palaeontological material from the Upper Pleistocene deposits and in this paper we describe and interpret data of the

ACCEPTED MANUSCRIPT

multidisciplinary analysys. The main aim of our research was to reconstruct palaeoenvironment in the surroundings of the Bokhan site on the basis of radiocarbon dating, geochemical and palaeontological material and to correlate new data with published materials.

Fig. 1 Here

RI PT

2. Regional setting

The Baikal Siberia region is conventionally divided into three natural units: Fore-Baikal, NearBaikal, and Trans-Baikal areas – the division based on the regional morphotectonics. The

SC

Baikalian Rift Zone occupies the central position in Baikalian Siberia. The zone consists of a chain of Cenozoic intracontinental rift valleys surrounded by high mountain ranges (more than

M AN U

3000 m a.s.l., the highest point is 3491 m). The mountain relief is noted for landforms typical of the mountain (Alpine) glaciation and the presence of the glaciers in the uppermost zone. Tectonically, the mountains of the Baikalian Rift Zone form a system of end-to-end joined tilted horsts oriented from SW to NE. The ranges form an important orographic barrier on the way of the main moisture-bearing air masses within Central Asia.

Morphotectonically, the Fore-Baikal region is a southern protrusion of the Siberian Platform

TE D

encircled with folded mountains of the Baikalian Rift Zone. Mountain systems join each other in the south forming a giant horseshoe open to the north and known as the Irkutsk amphitheater. There are two parts distinguishable in the latter – the inner part occupied by the Angara-Lena Plateau (1000-1500 m a.s.l.) and the marginal part. The latter is distinguished for block tectonics

EP

related to the Baikalian rift and folding structures recognizable within the Mezo-Cenozoic sedimentary cover. Those marginal structures of the Irkutsk Amphitheater are seen in the

AC C

topography as hilly plains drained by large river systems (Atlas, 2005). In the south of the Siberian Platform the relief evolution through the Late Cenozoic was mostly controlled by the general intermittent uplift and related erosional dissection of the ancient planation surface. The conditions were unfavorable for accumulation of loose deposits, except for some areas of differentiated tectonic movements superimposed on the general uplift. The thickness of the Quaternary sediments within the considered region vary between 5 and 25 m, except for a few blocks where it reaches 50 m or slightly more (Logachev et al., 1964). The most active processes of the Quaternary lithogenesis in the region were confined to the valley network (the Angara and Lena drainage basins). The sediment accumulation processes take place mostly along with (and in relation to) the erosion and deposition activities of streams belonging to those two large river systems. Of the deposits confidently attributable to the Late

ACCEPTED MANUSCRIPT

Pleistocene (Logachev et al., 1964), first should be mentioned fluvial deposits of the young terraces (less than 40 m above the stream channel) and the mantle of deluvial and solifluction slope deposits occurring on the terraces and slopes in the south of the Siberian Platform. A prominent place in the Quaternary deposits of the considered region is occupied by subaerial series – silty loams and sandy loams of deluvial, solifluctional and aeolian origin. They occur as large fields or spots on slopes of the river valleys or smaller linear hollows (pad’) usually devoid

RI PT

of stream and often are found on the watersheds. The covering deposits are often represented by loess-like varieties. They occur mostly on the sides of large river valleys where they contribute to the leveling of the buried relief irregularities. Their thickness varies considerably, reaching its maximum (25-30 m) at the back of terraces, in buried gullies, and small valleys, and over karst

SC

depressions (Bratskoye Vodokhranilishche, 1976). The covering series not infrequently include buried soil horizons, mostly of Karginian age (MIS 3), more rarely – Kazantsevo (MIS 5)

M AN U

(Vorob’yeva, 2010). The maximum of the loessial mantle deposition (and, therefore, the peak of aeolian activity) in the south of East Siberia falls on the second half of the Late Pleistocene. There was no ice sheet in Baikalian Siberia during the Late Pleistocene. The Alpine glaciers persisted, at intervals, until the end of the Pleistocene. The load of the glacier ice caused the Earth’s surface to sink approximately by 400 m below its present-day position. As the glaciers melted, the load was gradually reduced and finally disappeared about 12–13 ka BP. That resulted

TE D

in an active post-glacial rebound of the formerly glaciated regions; they underwent an uplift proceeding at a rate 3 to 4 times greater than the uplift rate in unglaciated areas of the Baikal region (Atlas, 2005). All that formed rather specific environments for the Early Man in the region. The Fore-Baikal area lies west of Lake Baikal and is actually a periglacial margin of

EP

Southern Siberia (Fig. 1). The Fore-Baikal area lies in the inner part of the continent far from the oceans, which accounts for a sharp continental climate, with mean annual temperatures being

AC C

typically below zero (from -5.4°C to -0.6°C) and annual precipitation amount rather low. Typical are severe and prolonged winters and frosts occurring early in autumn and late in spring.

3. Material and methods

3.1. Stratigraphical and chronological study

During field excavation of the deposits (3 meters thick) of the Bokhan site Upper Pleistocene and Holocene intervals were determined. The colors of the Munsell Soil Color Chart have been used to describe the natural sediment before drying.

ACCEPTED MANUSCRIPT

In this study we followed the general stratigraphic subdivisions of the Russian Stratigraphic Scale (Zhamoida et al., 2006). The Neopleistocene, a unit of the General Stratigraphic Chart of Russia, is correlated with the Brunhes palaeomagnetic epoch of normal polarity and can be subdivided into Lower (0.78–0.427 Ma ago), Middle (0.427–0.127 Ma ago), and Upper (0.127– 0.01 Ma ago) Members. Each Member is subdivided into Horizons which are recognised as regional divisions. The determination of the regional stratigraphic divisions of the Fore-Baikal

RI PT

area and their age was carried out in accordance with the existing detailed scheme of stratigraphy of the Upper Neopleistocene subaerial deposits, based on materials of pedolytic studies of geoarchaeological key objects of the region, provided with archaeological, radiocarbon dates, OSL-dating and palaeofaunistic findings (Vorob’yeva, 2010; Vorob’yeva et al., 2010;

SC

Shchetnikov et al., 2015 a, b, 2016). The upper part of the Neopleistocene (= Upper Pleistocene of the International Stratigraphic Chart, Cohen, Gibbard, 2016) of the Fore-Baikal area is

M AN U

subdivided into four horizons with local names: Kazantzevo (corresponds to MIS 5), Murukta (MIS 4), Karginian (MIS 3) and Sartanian (MIS 2).

Absolute data were obtained at the Radiocarbon laboratory of the Museum of The University of Tokyo (Tokyo, Japan) (C14 cal) following standard methodology.

TE D

3.2. Geochemical analysis

Petrochemical analysis (14 samples; sampling range is 0.2 m) was performed in order to determine the composition of the terrigenous deposits of the Bokhan section. Trace and rare element composition (Sc, V, Cr, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Ba, Pb, Th, U) was

EP

analysed by X-ray fluorescent method (the laboratory of instrumental methods of analysis of GIN SB RAS), content of eight major and two minor oxides were determined by wet chemical

AC C

analysis. Loss of ignition was determined at 1000°C. Oxide contents analysis results were recalculated to the ignited non carbonate bar, and then to the molar mass for primary petrochemical parameters evaluation. Statistical analysis of these results was made using the Statistica 10.0 software.

In order to obtain the general characteristics of the section sediments, we calculated the main petrochemical indices and pedogenic ratios listed in Table 1.

Table 1 Here.

In order to determine the degree of weathering we used the following weathering proxies: chemical index of alteration CIA=(Al2O3 / (Al2O3 + CaO + Na2O + K2O))*100 (Nesbitt, Young,

ACCEPTED MANUSCRIPT

1982), chemical index of weathering CIW = (Al2O3/(Al2O3 + CaO + Na2O))*100 (Fedo et al., 1995), index of compositional variability ICV = (Fe2O3 + K2O + Na2O + CaO + MgO +TiO2)/Al2O3 (Cox et al., 1995). Variations in geochemical proxies (LOI, Cu, Zn, Cu/Zr, Co/Zr) across the section were used for establishing the climatic conditions during sedimentation.

RI PT

3.3. Palynological analysis

Fifteen samples were selected for palynological analysis, with an interval of 0.20 m between them. The pollen diagram was compiled using Tilia 1/5/12 software developed and kindly

SC

provided by Dr. E. Grimm (2010). According to that technique, the general composition of the spectra is counted (arboreal pollen + non-arboral pollen + spores = 100%), and a proportion of

M AN U

individual components of the pollen assemblage is expressed as a percentage of total number of counted grains. The study of palynological preparations was carried out at the Geological Institute, RAS (Moscow) on an optical microscope Motic BA 400 with Moticam 2300 camera, with an operating magnification of ×400. All kinds of spores and pollen in the sample are determined. In the case of a small number of palynomorphs, all the instances encountered are

3.4. Faunal analysis

TE D

counted.

The traditional methods of dispersal of sediments in water, using sieves with a mesh size of 1.0

EP

and 0.5 mm were used to recover the molluscan and vertebrate remains. Mollusc remains were represented by 141 complete mollusc shells and occasional shell

AC C

fragments were found. The mollusc species determination was done according to Kerney and Cameron (1999), Likharev and Rammelmeier (1952), Sysoev, Shileyko (2009), and Falkner et al. (2002). The shells of molluscs were photographed at the Institute of Geology UFRC RAS (Ufa) on a stereomicroscope Motic SMZ–171 with a camera Moticam–10x. Small mammal teeth and bones (~113 items) can be attributed to lagomorphs and rodents. Molluscs were studied in the Institute of Geology, Ufa Federal Research Center RAS (Ufa) and vertebrates were studied at the Geological Institute of SB RAS (Ulan–Ude).

4. Results

4.1. Stratigraphy and Chronology

ACCEPTED MANUSCRIPT In the vicinity of Bokhan village, Upper Pleistocene and Holocene deposits of slope (colluvial) and subaerial (soil) genesis were excavated, which filled a small buried paleo-ravine. The Bokhan geological section consists of the following sediments (from base to top) (Fig. 2): Layer 1. Brown dense loam (10YR4/4) colored by iron oxides with lenses and interlayers of gravel sand, with fragments of rocks. Visible thickness of the sediments is 1.0 m.

RI PT

Layer 2. Brown dense and massive loam (10YR4/4) with slightly expressed platy structure, with numerous molehills filled with modern soil. Bone remains of the horse (jaw with teeth) and fragments of a large-mammal skeleton were found in the upper part of the layer. The lower boundary of the layer is poorly expressed and gradual. Thickness is 1.1 m.

SC

Layer 3. Light brown finely porous dense loam (10YR4/6) which is whitish due to carbonates, with grass roots inclusions, with pseudomycelia and molehills. The lower boundary is poorly

M AN U

expressed and gradual. Thickness is 0.4 m.

Layer 4. Dark gray homogeneous not laminated sandy loam (2.5Y3/1) with a sharp, well expressed almost horizontal lower boundary. This is a layer of the modern soil which is used for the agricultural purposes. Thickness is 0.5 m.

Results of the radiocarbon (AMS) dating of the jaw of a collared lemming Dicrostonyx sp. from the layer 2 have two dates: 20,221 ± 52 BP (TKA–17724) and 20,066 ± 52 BP (TKA–17725),

Fig. 2. Here

EP

4.2. Geochemistry

TE D

which indicates part of the Sartanian (MIS 2) interval of the Late Pleistocene.

AC C

Variations in the contents of major oxides, LOI and CO2 in the sediments of the Bokhan section are shown on Figure 3A, variations of trace and rare elements are shown on Figure 3B. Variability of petrochemical indices is presented on Figure 4. Figure 5A-C shows variation of all geochemical indices with depth. The profile distribution of the studied indices display the change of the sedimentation conditions: atmospheric and ground humidity, palaeotemperatures. Hypothetical model of the climate change in the sedimentary environment of the Bokhan section is shown with red lines on Figure 5C.

Fig. 3 here. Fig. 4 here. Figure 5 here.

ACCEPTED MANUSCRIPT 4.3. Palynology

The palynological analysis shows that a saturation of samples with pollen grains was uneven (Figs. 6 and 7). The reduced amount of pollen and spores grains of a bad preservation was found in the dense brown loam of the layer 3 (depth of 0.9–1.7 m). Single redeposited Neogene pollen

RI PT

grains of Pinaceae gen. indet., Podocarpus, Tsuga, and Ulmaceae exist throughout the section. A variety of freshwater algae Pediastrum, Cosmarium, Zygnema-type, and Botryocoсcus were found in the deposits at 0.5 m depth. The lower parts of layer 4 contains the largest

concentrations of green algae spores. The presence of freshwater algae indicates forming of the

SC

sediments in standing (lakes) or weakly-flowing waters (rivers).

Four palynological complexes (PС), reflecting the main stages of vegetation development were

boundaries of this section.

M AN U

recognized in the Bokhan section; the boundaries of PC are coeval with the lithological

PC1 (1.8–2.7 m depth). The pollen of the herbaceous group (74–88 %) dominates in the palynospectra. Cichoriaceae pollen is numerous; pollen grains of Cyperaceae, Chenopodiaceae, Caryophyllaceae, Brassicaceae, Artemisia, and Ephedra are also present. The group of trees is represented by the single grains of Pinus, Betula sect. Fruticosae + Nanae and Duschekia

TE D

fruticosa. Polypodiaceae grew under the trees. The composition of freshwater algae is diverse and is rpresented by Pediastrum, Cosmarium, Zygnema-type, and Botryococcus. This palynocomplex indicates a wide distribution of treeless meadow-steppe landscapes and cold climate conditions.

EP

PC2 (0.8–1.8 m depth). The spectra of the PC2 are similar to spectra of the PC1, however, PC2 spectra are poorly saturated with pollen grains. The pollen of grasses continued to dominate and

AC C

the amount of Asteraceae increased in the spectra. The pollen of Betula sect. Fruticosae + Nanae and Duschekia fruticosa were not present in spectra. The part of the water plants slightly reduced. The open meadow-steppe landscapes continued to dominate. PC3 (0.4–0.8 m depth). In this the amount of tree pollen is 1–8 % (Pinus, Picea, Betula sect., Fruticosae + Nanae, Salix). The amount of Artemisia and Asteraceae pollen increased; the number of Cichoriaceae pollen was reduced. There is an underdeveloped pollen of dicotyledonous herbaceous plants. The number of spores (Polypodiaceae, Diphasiastrum alpinum, Botrychium) is slightly increased up to 11 %. Spores of green algae are represented only by the grains of Botryococcus. Treeless landscapes continue to prevail and they were represented by meadow-steppe associations in combination with small areas of tundra vegetation in cold and arid climate conditions.

ACCEPTED MANUSCRIPT

PC4 (0.1–0.4 m depth). This PC characterizes modern soil. It was noted that the part of tree pollen dominates (70–80 %). Their spectra contain a significant quantity of pines, including Pinus sylvestris and Pinus sect. Cembrae. Pollen of Betula, Picea, and Salix also occur in this complex. Grass pollen is represented by Asteraceae, Artemisia, Chenopodiaceae, and Caryophyllaceae. Soil fungi spores are also present in significant quantity in this spectrum. The spore and pollen composition of the spectra indicates widespread development of pine and pine-

RI PT

birch forests with small meadows.

The palynological data indicate significant changes in the composition of the pollen spectra of the Bokhan section at a depth of 0.4 m, which is correlated approximately with the boundary between first and second layers. At this boundary deposits were formed in the arid and cold

SC

conditions during Late Pleistocene when the treeless landscapes were covered by meadow-steppe vegetation. The presence of freshwater green algae indicates sediment forming in standing or

M AN U

weakly-flowing waters (lakes or rivers). Modern soil was formed during Holocene under the pine and pine-birch forests (Shchetnikov et al., 2015b; Simakova, 2017).

Figs. 6 and 7.

TE D

4.4. Malacology

Two mollusc’s associations collected in different years were studied. First association was sampled in 2012 from the deposits of the layer 2. In 2017 other mollusc assemblages were

EP

gathered from different layers of the section with spacing of 0.2 m between samples (Table 2). Shells of molluscs are distributed unevenly across the deposits. The largest number of shells is

AC C

concentrated at a depth of 1.5–1.7 m. A smaller number of shells was observed in the lower part of the section at a depth of 2.3–2.9 m. Shells of Succinella, Vallonia and Gyraulus are of a good safety with carbonate crust (CaCO3); shells of Pupilla are of a bad preservation. All mollusc’s shell belong to Gastropoda Class. Studies have shown that in the samples there are shells of terrestrial molluscs (3 species, 3 genera) and one freshwater mollusc shell (1 species), as well as single shell detritus. The species composition is presented in Table 2.

Table 2.

Succinella oblonga (Draparnaud, 1801) and Vallonia tenuilabris (A. Braun, 1843) are the main numerous species.

ACCEPTED MANUSCRIPT

Succinella (Fig. 8). Genus is represented by S. oblonga (Draparnaud, 1801). The shell is highconispiral (shell height is 7.5–5.0 mm; shell width is 2.0–4.0 mm), thin-walled. The shell has 3– 3.5 whorls marked with thin and even striae which are separated with a deep suture; the top whorls are convex; the last whorl is less convex than the previous one. The aperture is oval, arrow-headed at the top; lip of the aperture is thin, the inner edge of the aperture borders the shell, covering the umbo.

RI PT

Vallonia (Fig. 8). The genus is represented by the species V. tenuilabris (A. Braun, 1843). The shell is low-conispiral (shell height is 2.0–1.5 mm; shell width is 3.0–2.2 mm) with thin and even striae. The shell has 3.5 convex whorls separated with a deep suture. The last whorl is widened and lowered to aperture. The aperture is rounded; the outer edge of the aperture is thin, slightly

SC

turned out, not thickened. The umbo is open and wide.

Pupilla (Fig. 8). Shells are represented by Pupilla muscorum (Linnaeus, 1758). The shell has

M AN U

oval-cylindrical form (shell height is 3.0 mm; shell weight is 1.8 mm) with rounded obtuse apex. The shell has 6-6.5 weekly convex whorls with thin and even striae separated with almost horizontal shallow suture. The aperture is semicircular with slightly turned away well developed lip; the palatal edge has a distinctive “constriction”; the aperture of all studied shells lacks teeth. Umbo is small and narrow.

Gyraulus (Fig. 8). Only one shell of Gyraulus laevis (Alder, 1838) represents this genus, was

TE D

found in the deposits. The shell is planispiral (shell height is 0.7 mm; shell width is 2.9 mm) thin-walled, the upper side is concave. The shell has 3.5 rapidly growing whorls with thin striae separated with deep suture. The whorls are not keeled. The aperture is rounded, oblique, the

AC C

Fig. 8.

EP

upper edge is extended forward.

4.5. Herpetology

Fragments of the Lacerta sp. jaws were the only reptiles identified (Schepina et al., 2016). This green lizard found on the sloping hills and ravines covered with grass and bushes most often.

4.6. Mammalogy

The species composition of the Bokhan mammal fauna includes 16 taxa. Mammal teeth were collected from the dark-brown sandy loam of layer 2 in 2012. Additional mammal bone material

ACCEPTED MANUSCRIPT

was collected from layers 1–3 in 2017 which completed the list of the previously determined species (Table 3). Species composition of small mammals is represented by steppe, tundra and taiga species. So, narrow-skulled voles Microtus gregalis Pallas and steppe lemming Lagurus lagurus Pallas are typical inhabitants of the steppe landscape; Siberian lemming Lemmus sibiricus Kerr, collared lemming Dicrostonyx guilielmi Sanford, and North Siberian vole Microtus hyperboreus

RI PT

Vinogradov are typical tundra species; Amur’ lemming Lemmus amurensis Vinogradov preferred to live in the taiga forest as well as Clethrionomys rutilus Pallas which is forest inhabitant. Key small-mammal species are represented on the Figure 9.

The megafauna is represented by Alopex lagopus (Linnaeus, 1758), Equus sp., Coelodonta

SC

antiquitatis Blumenbach, 1799, Rangifer tarandus (Linnaeus, 1758), Bos sp., Bison sp., and Mammuthus primigenius Blumenbach, 1799 and is typical of the Late Palaeolithic (or

mammoth tusk at a depth of 1.3 m.

M AN U

Mammoth) faunal complex (Gromov, 1948). It should be noted the find of the fragment of the

The mammal species composition of the fauna of the Bokhan section indicates a moderately cold and dry climate during Sartanian time and the presence of tundra-steppe landscapes.

Table 3. Here.

TE D

Fig. 9. Here.

5. Discussion

EP

5.1. Stratigraphy and Chronology

AC C

Two AMS dates (see subchapter 4.1) and lithology of the studied deposits permitted to attribute layers 1–3 to the Sartanian Horizon (MIS 2) according to a correlation with similar deposits in the vicinity of the site that provide a detailed stratigraphic succession of the Upper Pleistocene subaerial deposits of the Fore-Baikal area (Vorob’yeva, 2010; Vorob’yeva et al., 2010; Shchetnikov et al., 2015a, 2016), based on pedolytic, geoarchaeological and paleozoological arguments in combination with radiocarbon and OSL–dating.

5.2. Geochemistry

In general, the sediments of the Bokhan section show relatively small variations in the contents of the main oxides and trace/ rare elements (Fig. 3 A, B). All components vary slightly; their

ACCEPTED MANUSCRIPT

variations do not exceed 30 %, except of CaO, LOI, CO2, Pb and Mo. CO2 content varies highly, from 0.22 % to 6.82 %, while its median values are 5.06 %. It suggests the presence of the weathering crust developed in arid zones in the provenance rocks and the noticeable carbonatization. Due to dependence solely on lithological conditions, the carbonatization process can take place practically in any climatic conditions. However, being directly associated with migration processes (irrigation and leaching), carbonatization may not be fixed in the soil

RI PT

profile in the form of carbonates. In humid regions in well drained soils this process can be diagnosed only in the liquid phase – in soil solution. Thus, the solid-phase effect of

carbonatization is observed only in arid regions, where the process is associated with the accumulation of carbonates.

SC

Loss on ignition (LOI) reflecting relative content of organic compounds in sediments varies from 7.48 to 15.37 % (the median value is 11.07 %). The maximum values of this parameter are typical for sediments formed in warm periods. Commonly such sediments have an increased

M AN U

contents of organic C, S and N. Positive direct correlation of LOI and Cu (K= 0.7) contents is observed. The peak of LOI content is observed in the soil horizon (layer 4). Calculated values of most petrochemical indices (Table 1, Fig. 4) are typical for the sandysilty sediments. The range of the values of AM, ASM and NAM indicates the predominance of mica and low content of clay minerals in the mineral composition of the initial deposits

TE D

(Yudovich, Ketris, 2000).

The maximal variations are observed for AM, NAM, HM and ASM indices, so it is obvious that these parameters will be the most sensitive indicators of the weathering processes (see Table 1). These indices characterize the behavior of readily soluble salts (AM, NAM) and the

EP

intensity of hydrolysis processes (HM and ASM). Variations of the indices characterizing the salinization in the profile distribution (Table 1, Fig. 5

AC C

A) show the sharp increase in the degree of the sediments salinization in the formation of the layer 1 deposits and at the boundary between layers 4 and 3. Accumulation of soil carbonates (illustrated by the increasing of the values of the calcification index (CaO+MgO) / Al2O3 ) mainly occurs at the formation of the layer 2 deposits (Fig. 5 A). The sharp decrease of the calcification index is observed at the boundary between layer 4 and layer 3. It suggests the most humid conditions existed at this time. Noticeable changes of the sedimentation redox conditions index ((Fe2O3+MnO) / Al2O3) are observed in the formation of deposits of the lower part of the section (layer 1 and the lower part of layer 2) and upper part of the layer 4. The sharp increase of the values of normalized alkalinity index (NAM) (Fig. 5 A) while reducing of the values of the alkaline index (AM) can be explained by the presence in the initial

ACCEPTED MANUSCRIPT

sediments the carbonate rocks which contain the autigenic feldspars in the mineral composition. The profile distribution of the titanium index (TM) (Fig. 5 A) is suggesting the genetic homogeneity of provenance rocks. The CIA values varying from 37 to 61 and ICV values varying from 1.1 to 1.8 suggest arrival into the sedimentation area of the immature material of the weathering products of basic and acid igneous rocks. The index of compositional variability ICV slightly ranges through the

RI PT

section (see Fig. 5 C). However fine sediments have high values evidencing the increase of eolian accumulation (ICV values over 1 imply low rock maturity, i.e. minor amount of clay minerals in sedimentation area). Thus, the variations of ICV index along the profile suggests an increase in the share of eolian material in the formation of sediments of the middle part (layers 2

SC

and 3) of the section. The observed СIА indicates arid or subarid climatic settings in the provenance areas. The chemical index of weathering (CIW) in the studied sediments varies

M AN U

from 39 to 66 (median 44.6), which also indicates an insignificant level of rock alteration at paleo catchment area. The changes of CIW and ICV proceed synchronously, and the increase of CIW values with a simultaneous ICV decrease marks the periods of climate humidization. The values of index A / CMKN (Table 1, Fig. 5 A) characterizing an intensity of hydrolysis change synchronously to ICV. The profile distribution of Ba / Sr ratio shows the greatest intensity of hydrolytic weathering and leaching in the formation of sediments of the layers 1

TE D

and 4.

The accumulation of other trace elements in the deposits of the section is connected with their biogenic accumulation. The maximum increases in the concentrations of Zn and Cu (Fig. 5 B) are recorded at the stages with the highest degree of atmospheric moisture and at the present

EP

stage, when activization of biological activity took place on the territory. Minimum values are observed during periods of climate aridization. The decrease of the values of the Co / Zr, Cu /

AC C

Zr ratios (Fig. 5 B) marks periods of cooling, since in cold conditions, in the presence of a seasonally melted layer, Cu, Co are removed from the sediments more intensively than in taiga landscapes, and Zr is inert. The profile distribution of the studied geochemical indices (Fig. 5 A–C) displays the change of the sedimentation environment conditions: atmospheric and ground humidity and temperature. Based on a set of the geochemical data, a hypothetical model of the climate change in the sedimentary environment of the Bokhan section is constructed and shown on the Fig. 9 C (red lines). Thus, the results of the study of the sediments chemical composition allow to establish that during formation of the section sediments the geochemical indices of the intensity of salinization (AM, NAM), calcification ((CaO + MgO) / Al2O3), oxidation (Fe2O3 + MnO) /

ACCEPTED MANUSCRIPT

Al2O3, leaching and hydrolysis (Ba / Sr) and weathering (CIA, CIW and ICV) change cyclically. The results of the study of the sediments chemical composition at the Bokhan section allow concluding that the climate changes during the section formation were cyclic. The most humid and warm conditions and activation of weathering and leaching processes are established for the deposits of the layer 4. The observed variations of the geochemical

RI PT

indices are consistent with the data of the spore-pollen analysis, according to which the most noticeable changes in the composition of the pollen spectra of the Bokhan section occur approximately at the boundary of layers 3 and 4.

SC

5.3. Palynology

M AN U

Open meadow-steppe and tundra-steppe landscapes reconstructed from palynological data dominated during the last glaciation (Sartanian) and during the Late Glacial transition in the Baikal region. Rare forest patches are recorded in warm intervals of the Late Glacial time (Bezrukova et al., 2008: Bezrukova et al., 2011; Tarasov et al., 2009, Simakova, 2017). The Holocene is dominated by pine and pine-birch boreal forests with small areas of meadow vegetation (Shchetnikov et al., 2015, Simakova, 1917).

TE D

Diverse freshwater algae (Pediastrum, Cosmarium, Zygnema–type, and Botryococcus braunii) were recorded from layers 2–4 at a depth of 0.5 m and the highest concentrations of green algae was confined to the lower part of layer 4. The presence of freshwater algae

EP

indicates that sediments were formed in low-flow waters.

AC C

5.4. Malacology

The terrestrial molluscs found in the Sartanian horizon are widespread, well-adapted and coldresistant species. Mostly they lived in biotopes with high humidity, but at the same time, they could live in relatively dry places. They lived in the floodplain in the river valley or on the water meadow near the pond. The species Succinella oblonga is hydrophilic, and therefore could live directly near the water on the vegetation. The molluscs Pupilla muscorum and Vallonia tenuilabris lived under the fallen leaves, in moss and wood dust, which indicates the presence of woody vegetation and grasses. The freshwater gastropod Gyraulus laevis lived on the water plants in small flood-plain lakes at a depth of 0.20–1.50 m. Based on the malacological data, it can be assumed that during the formation of the Sartanian horizon river existed, bushes and

ACCEPTED MANUSCRIPT

forests possibly grew on the banks of the river and the open landscapes existed on the interfluves.

5.5. Mammalogy

Mammal fauna of Bokhan locality (Table 3) was disharmonious, ecologically mixed, and has no

RI PT

analogue in recent time (Fig. 10). As known, the Late Pleistocene faunal assemblages are often composed of the mammalian species whose present ranges are entirely separated. They have been recorded in several regions of Eurasia, North America and Australia (Nadachowsky, 1982; Lundelius, 1983; Semken, 1988; Kochev, 1992; Khenzykhenova, 1999; Sato et al., 2014;

SC

Smirnov et al., 2016; Markova et al., 2013, etc.). These faunas have no recent analogues and they are called “ecologically mixed”, “lemming”, “periglacial” or “intermingled” faunas. This is the

M AN U

phenomenon of the Late Pleistocene faunas of Eurasia, North America and Australia, when tundra, steppe, and forest species could live together, while their modern habitats are located in different natural zones and do not intersect each other. Figure 10 shows the ranges of modern tundra species and the steppe Lagurus lagurus, a semi-desert and dry steppe species (the range is highlighted in orange) and a small area in Tuva. In modern conditions, tundra and dry steppe species are not apear together, as well as dry steppe and taiga species. The coexistence of such

TE D

different ecology of animals was proved using the AMC method (see the references above). In the Fore-Baikal region, such Pleistocene faunas were found in the Igetei, Malta, Bolshoi Yakor, Bolshoi Naryn localities.

No-analogue, ecologically mixed faunas of the Fore-Baikal region are known from the Middle

EP

Pleistocene Igetei geo-archaeological site (the Bratsk Reservoir), from the Late Pleistocene Malta and Buret’ sites and Gerasimov’ settlement close to Irkutsk city, from the Bolshoi Yakor

AC C

settlement on the Vitim River near Bodaibo city. A characteristic feature of no-analogue faunas is the coexistence of dry-steppe and tundra species. The small-mammal association contain about 17 species of insectivores and lagomorphs. The Dicrostonyx cf. simplicior Feifar is a transitional form between the Middle Pleistocene D. simplicior and Late Pleistocene D. guilielmi. Gromov and Erbajeva (1995) and Gromov and Polyakov (1977) gave a modern distribution of some small-mammal species found in the Bokhan site. Summary of these characteristics is given below. Nowadays, Lagurus lagurus Pallas inhabits the southern forest-steppe and northern deserts of Eurasia. This species is known from Middle Pleistocene when occurred on a wide area from Great Britain Islands in the west to the Trans-Baikal area in the east.

ACCEPTED MANUSCRIPT

Microtus gregalis Pallas inhabits open landscapes of plains as well as mountains and occurs from tundra to alpine meadows. The areal of this species currently is divided into two parts – the northern (tundra) and the southern (steppe and mountain) areas. In the past, starting from Middle Pleistocene, this species was widely distributed and is known from the sites of the westernmost part of Europe (France), central parts of the Eastern-European plain and Siberia. The Lemmus sibiricus Kerr species nowadays inhabits tundra in mountains and forest-tundra of

RI PT

the wide area of the mainland and some islands and is distributed from Baltic and White Seas in the west to Kolyma River in the east. Fossil remains of this species are known from the Early Pleistocene.

The modern Dicrostonyx torquatus Pallas, 1779 area covers the arctic and subarctic tundra and

SC

the northern forest-tundra of the Eurasia and Northern America, including the islands of the polar basin. The fossil remains of Dicrostonyx are known from the second half of the Pleistocene.

M AN U

Microtus hyperboreus Vinogradov nowadays inhabits dry steppe areas on the banks of the river terraces with sandy or stony and sandy soil. This species is distributed in the mountainous regions of the Central Siberia from Yenisei River to Indigirka and Kolyma Rivers. Lemmus amurensis Vinogradov is the only Palaearctic species of the genus Lemmus; it is distributed within the forest zone in the plain and mountains of the Trans-Baikal area and the FarEast. Late Pleistocene fossil remains of this species were found in surroundings of the Baikal

TE D

Lake (Khenzykhenova, 2001; Shchetnikov et al., 2015).

Recent Clethrionomys rutilus Pallas inhabits the forest, forest-tundra and forest-steppe zones of Eurasia, Japan, Alaska and the north-western part of Canada. Late Pleistocene fossils are known from the Siberia and the Far East.

EP

As the dating of the Bokhan site demonstrated, layer 2 is correlated to classical cultural layer of the famous Palaeolithic site of Malta (Sartanian time; MIS 2) (Khenzykhenova et al., in press).

AC C

There is also a similarity in species composition, a mixture of steppe, tundra and intrazonal species. Both faunas are ecologically mixed, disharmonious and characteristic for the cold times of Eurasia during the Late Pleistocene (Khenzykhenova et al., in press). The species composition of the fauna of Bokhan indicates a moderately cold climate and the presence of tundra-steppe landscapes.

Fig. 10. Here.

5.6. A summary palaeoenvironmental considerations

ACCEPTED MANUSCRIPT

The palaeoecological reconstructions were estimated using multy-proxi data, which indicate some changes in the conditions of the sedimentation, climate and landscape. All these changes are summarised in the Figure 11.

Fig. 11

RI PT

6. Conclusion

Deposits of the Bokhan section on the base of the mammal faunistic complex and according to the radiocarbon dates were attributed to the Sartanian time of the Late Pleistocene. The results of

SC

the various methods used for the Bokhan site study complete each other and make it possible to reconstruct the changes in the palaeoenvironment and climate during Sartanian time.

M AN U

1. The study of the sediments chemical composition allows concluding that the climate changes during the section formation were cyclic. The most humid and warm conditions and activation of weathering and leaching processes were established for the deposits of the layer 4. 2. Large mammals with key-species Rangifer tarandus, Mammuthus primigenius, and Alopex lagopus represented the Late Palaeolithic (Mammoth) faunal complex. 3. Species composition of the small mammals included tundra, dry steppe and intrazonal species;

Late Pleistocene.

TE D

that is periglacial, disharmonious fauna characteristic for the cold periods of Eurasia during the

4. During Sartanian time tundra-steppe landscapes dominated in the vicinities of the Bokhan site,

EP

the climate was moderately cold and dry.

AC C

Acknowledgements

This research was supported by following grants: RFBR N 16–05–01096; 16–05–00586; Fundamental Basic project IX.127.1.5, AAAA-A16-11621550056-9; State Assignment N 33.2057.2017 / 4/6 of the Ministry of Education and Science of the Russian Federation, RSF grant N 16–17–10079 (geomorphology), and Integration Project N 0341–2016–001. This work was partly achieved thanks to the State programmes N–0340–2016–0003, N–0252–2016–0006, N–0246–2019–0118, and the Russian Government Program of Competitive Growth of Kazan Federal University as well as this study was financially supported in 2012 by Grants-in-Aid for Scientific Research (KAKENHI) from Japan Society for the Promotion of Science (JSPS) (Grant Number 25300037).

ACCEPTED MANUSCRIPT

We are grateful to Professor of the Hokkaido University (Japan) Hirofumi Kato and our colleagues – archaeologists of Irkutsk State University Ekaterina Lipnina and Dmitry Lokhov. The authors also want to thank the reviewers for their useful comments and the editors and the editorial board of Quaternary International for their help.

Availability of the data. The palaeontological collections are kept at the Institute of Geology

RI PT

UFRC RAS (Ufa) and Geological Institute of SB RAS (Ulan–Ude).

References

SC

Abramson, N.I., 1993. Rod Lemmus v pozdnem kajnozoe Evrazii. Materialy` po mezozojskoj i kajnozojskoj istorii nazemnyh pozvonochnyh [The genus Lemmus in the Late Cenozoic of

M AN U

Eurasia. Materials on the Mesozoic and Cenozoic history of terrestrial vertebrates] (Proceedings of the Zoological Institute of the Russian Academy of Sciences. Vol. 249. P. 146–157) (in Russian).

Atlas of the Lake Baikal. Past. Present. Future, 2005. FGUP Eastern-Siberian Aerogeodesic enterprise, Irkutsk. 117 p. (in Russian and English).

Bratskoe vodohranilische. Injenernaya geologiya territorii, 1976. [Bratsk reservoir. Engineering

TE D

geology of territory]. Odintsov, M.M. (Ed.). Publishing House of the USSR Academy of Sciences. Moscow. 276 p. (in Russian).

Cohen, К.М., Gibbard, Рh., 2016. G1obal chronostratigraphical correlation table for the last 2.7 million years. V.2016a. Subcommission on Quatemary Stratigraphy (Intenational Commission).

EP

Cox, R., Lowe, D.R., Cullers, R.L., 1995. The influence of sediment recycling and basement composition on evolution of mudrock chemistry in southwestern United States. Geochimica et

AC C

Cosmochimica Acta 59, 2919–2940. Falkner, G., Ripken, T.E.J., Falkner, M., 2002. Mollusques continentaux de France. Liste du references annotees et Bibliographie. Patrimoines naturels 52, 1–350 (Museum National d’ Histoire Naturelle (Paris), France). Fedo, C.M., Nesbitt, H.W., Young, G.M., 1995. Unraveling the effects of potassium metasomatism in sedimentary rocks and paleosols, with implications for paleoweathering conditions and provenance. Geology 23, 921–924. Gerasimov, M.M., 1931. Paleoliticheskaya stoyanka v Mal'te [Palaeolithic Site in Malta]. Communications of State Academy of history of material culture 11/12, 55-57 (in Russian). Grazhdankin, D.V., Maslov, A.V., 2012. Litokhimicheskie osobennosti primitivnykh paleopochv v razreze srednei chasti bederyshinskoi podsvity zil'merdakskoi svity verkhnego rifeya na

ACCEPTED MANUSCRIPT

yuzhnoi okraine g. Min'yar [Lithochemical features of primitive paleosols in the section of the middle part of the Bedeshinsky subsuite of the Zilmerdak suite of the upper Riphean on the southern of Minyar city]. Ezhegodnik–2011. P. 77–84 (Proceedings IGG UrO RAN; v. 159) (in Russian). Grimm, E.C., 2011. TILIA and TILIA.GRAPH. Illinois State Museum, Springfield. Gromov, I.M., Erbajeva, M.A., 1995. Mlekopitajuschie fauny Rossii i sopredel'nyh territorij.

RI PT

Zajtseobraznye i gryzuny [Mammals of the fauna of Russia and adjacent territories. Leporidae and rodents. St. Petersburg. 522 p. (Determinants on the fauna of Russia, published by the Zoological Institute of the Russian Academy of Sciences; iss. 167) (in Russian).

Gromov, I.M., Polyakov, I.Y., 1977. Polevki (Microtinae) [Voles (Microtinae).. Nauka Press,

SC

Leningrad. 504 p. (Fauna of the USSR. Mammals; v. III, iss. 8] (in Russian).

Gromov, V.I., 1948. Paleontologicheskoe i arheologicheskoe obosnovanie stratigrafii

M AN U

kontinental'nyh otlozhenij chetvertichnogo perioda na territorii SSSR (mlekopitayushchie, paleolit) [Paleontological and paleontological substantiation of the stratigraphy of continental deposits of the Quaternary period in the territory of the USSR (mammals, Palaeolithic)]. Moscow 521 p. (Proceedings of the Institute of Geological Sciences. Geological series; v. 64) (in Russian).

Kalinin, P.I., Alekseev, A.O., Savko, A.D., 2009. Lessy, paleopochvy i paleogeografiya kvartera

TE D

yugo-vostoka Russkoi ravniny. [Loesses, paleosols and paleogeography of Quaternary of southeast of the Russian Plain]. Voronezhskii gosudarstvennyi universitet Press,Voronezh, 132 p. (in Russian).

Kerney, M.P., Cameron, R.A.D., 1999. Guide des Escargots et limaces d’ Europe. Delachaux et

EP

Niestle S.A. 3, Lausanne, 70 p.

Khenzykhenova, F.I., 1999. Paleolithic disharmonious faunas of the Baikal Region (Russia,

AC C

Siberia) and its implication for Paleogeography. Anthropozoic 23, 118–121. Khenzykhenova, F., Lipnina, E., Danukalova, G., Shchetnikov A., Osipova E., Semenei E., Lokhov D. The area surrounding the world-famous geoarchaeological site Mal'ta (Baikal Siberia): New data on the chronology, archaeology, and fauna. Quaternary International, DOI: 10.1016/j.quaint.2018.02.026 in press. Kochev, V.A., 1992. Plejstocenovye gryzuny Severo-Vostoka Evropy i ih stratigraficheskoe znachenie [Pleistocene rodents of the Northeast of Europe and their stratigraphic significance. Nauka Press, St.Petersburg, 112 p.] (in Russian). Kolfschoten, van T., 1995. On the application of fossil mammals to the reconstruction of the palaeoenvironment of northwestern Europe. Acta zoologica 38 (1), 73–84.

ACCEPTED MANUSCRIPT

Likharev, I.M., Rammelmeier, E.S., 1952. Nazemnye molluski fauny SSSR [Land molluscs of the Fauna of the USSR]. Academy of Sciences of USSR Press, Leningrad, Moscow, 511 pp. (Determinative Tables of the USSR Fauna. Proceedings of the Zoological Institute of the USSR Academy of Sciences; v. 43) (in Russian). Logachev, N.A., Lomonosova, T.K., Klimanova, V.M., 1964. Kaynozoyskiye otlozheniya Irkutskogo amfiteatra [Cenozoic deposits of the Irkutsk amphitheater]. Nauka Press, Moscow,

RI PT

195 p. (in Russian).

Lundelius, E.L., Jr., 1983. Climatic Implications of Late Pleistocene and Holocene faunal associations in Australia. Alcheringa 7, 125–149.

Markova, A.K., Puzachenko, A.Yu., van Kolfschoten, T., van der Plicht, J., Ponomarev, D.V.,

SC

2013. New data on changes in the European distribution of the mammoth and the woolly rhinoceros during the second half of the Late Pleistocene and the early Holocene. Quaternary

M AN U

International 292, 4–14.

Markova, A.K., Smirnov, N.G., Kozharinov, A.V., Kazantseva, N.E., Simakova, A.N., Kitaev, L.M., 1995. Late Pleistocene distribution and diversity of mammals in Northern Eurasia (PALEOFAUNA Database). Paleontologia and Evolucio 28–29. Sabadell, 1–143 p. Maslov, A.V., 2005. Osadochnye porody: metody izucheniya i interpretatsii poluchennykh dannykh [Sedimentary Rocks: Methods for the Study and Interpretation of Obtained Data].

TE D

UGGU Press, Yekaterinburg. 325 p. (in Russian).

Medvedev, G.I., Slagoda, E.A., Lipnina, E.A., Berdnikova, N.E., Generalov, A.G., Rogovskoy, E.O., Oschepkova, E.B., Vorobyeva, G.A., Shmygun, P.E., 2001. Kamennyy vek Yuzhnogo Priangar'ya [Stone Age of the Southern Angara region]. V. 2: Belsk geoarchaeological region.

EP

Irkutsk University Press, Irkutsk. 242 pp. (in Russian). Nadachowsky, A. 1982. Late Quaternary rodents of Poland with special reference to Morphotype

AC C

dentition analysis of voles. PWN Press, Warszawa-Krakov. 108 p. Nesbitt, H.W., Young, G.M., 1982. Early Proterozoic climates and plate motions inferred from major element chemistry of lutites. Nature 299, 715–717. Panteleev, P.A., Terekhina, A.N., Varshavsky, A.A., 1990. Ekogeograficheskaya izmenchivost' gryzunov [Ecogeographical variability of rodents]. Nauka Press, Moscow. 374 p. (in Russian). Retallack, G.J., 2001. Soils of the Past: an Introduction to Paleopedology. Blackwell Press, Oxford. 2nd Ed. 600 p. Retallack, G.J., 2007. Soils and Global Change in the Carbon Cycle over Geological Time. In: H.D. Holland, K.K. Turekian (Eds.), Treatise on Geochemistry. University of Oregon, Eugene. P. 581–605.

ACCEPTED MANUSCRIPT

Sato, T., Khenzykhenova F., Simakova, A., Danukalova, G., Morozova, E., Yoshida, K., Kunikita, D., Kato, H., Suzuki, K., Lipnina, E., Medvedev, G., Martynovich, N., 2014. Paleoenvironment of the Fore-Baikal region in the Karginian interstadial: Results of the interdisciplinary studies of the Bol’shoj Naryn site. Quaternary International 333, 146–155. Semken, H.A., Jr., 1988. Environmental interpretation of the “disharmonious” Late Wisconsinan biome of southeastern North America. In: Laub, R.S., Miller, N.G., Steadman, D.W. (Eds.), Late

RI PT

Pleistocene and Early Holocene Paleoecology and Archaeology of the Eastern Great Lakes Region. Bulletin of the Buffalo Society of Natural Sciences 33, 185–194.

Sheldon, N.D., 2006. Abrupt chemical weathering increase across the Permian–Triassic boundary. Palaeogeography, Palaeoclimatology, Palaeoecology 231, 315–321.

SC

Sheldon, N.D., Tabor, N.J., 2009. Quantitative paleoenvironmental and paleoclimatic reconstruction using paleosols. Earth Science Reviews 95, 1–52.

M AN U

Schepina, N.A., Khenzykhenova, F.I., Namzalova, O.D.-Ts., 2016. Fauna zemnovodnyh i presmykayushchihsya pozdnego plejstocena i golocena Bajkal'skogo regiona (novye dannye) [Amphibian and Reptilian fauna of the Baikal region of Late Pleistocene and Holocene (new data). Bulletin of the St. Petersburg University. Series 3: Biology 4, 48–61. Shchetnikov, A.A., Semenei, E.Y., Filinov, I.A., Khenzykhenova, F.I., 2015a. New data on the Late Pleistocene stratigraphy and paleoenvironment of the South-Western Baikal area (Siberia).

TE D

Quaternary International 355, 65–79.

Shchetnikov, A.A., Khenzykhenova, F.I., Klement'ev, A.M., Simakova, A.N., Semenei, E.Y., Filinov, I.A., 2015b. Changes of environments and climate during the Late Pleistocene and Holocene reconstructed from aeolian and colluvial deposits of the Zaktui site (Tunka rift valley,

EP

Baikal region). Quaternary International 355, 80–89. Shchetnikov, A.A., Bezrukova, E.V., Maksimov, F.E., Kuznetsov, V.Yu., Filinov, I.A., 2016.

AC C

Environmental and climate reconstructions of the Fore-Baikal area during MIS 5-1: Multiproxy record from terrestrial sediments of the Ust–Oda section (Siberia, Russia). Journal of Asian Earth Sciences 129, 220–230.

Simakova, A.N., 2017. Rastitel'nost' vtoroj poloviny pozdnego neoplejstocena Bajkal'skogo Regiona po palinologicheskim dannym [Vegetation of the second half of the late NeoPleistocene of the Baikal Region according to palynological data]. XIV All-Russian Palynological Conference “Actual Problems of Modern Palynology” (Moscow, June 5–8, 2017)]. Moscow State University Publishing House, Moscow. P. 323–326 (in Russian). Smirnov, N.G., Bolshakov, V.N., Borodin, A.V., 1986. Plejstocenovye gryzuny Severa Zapadnoi Sibiri [Pleistocene rodents of the North Western Siberia]. Nauka Press, Moscow. 145 p. (in Russian).

ACCEPTED MANUSCRIPT

Smirnov, N.G., Izvarin, E.P., Kuzmina, E.A., Kropacheva, Y.E., 2016. Steppe species in the Late Pleistocene and Holocene small mammal community of the Urals. Quaternary International 420, 136–144. Sysoev, A., Shileyko, A., 2009. Land Snails and Slugs of Russia and adjacent countries. Pensoft Publishers, Sofia – Moscow, 312 p. Vorob’yeva, G.A., 2010. Pochva kak letopis' prirodnykh sobytiy Pribaykal'ya: problemy

RI PT

evolyutsii i klassifikatsii pochv. [Soil as a chronicle of natural events of the Baikal region: problems of evolution and classification of soils]. Irkutsk University Press, Irkutsk. 205 p. (in Russian).

Vorob’yeva, G.A., Berdnikova, N.E., Vashukevich, N.V., Arslanov, Kh.A., Ryzhov, Yu.V.,

SC

2010. Karginskiy megainterstadial Pribaykalya: harakter otlojeniy i problemy datirovaniya [Karginsky megainterstadial of the Baikal region: character of deposits and problems of dating].

M AN U

Problemy arheologii, etnografii, antropologii Sibiri i sopredelnyih territoryi. Materials of annual session of Institute of Archeology and Ethnography of the SB RAS (IAET SO RAS). V. 16. IAET SO RAS Press, Novosibirsk, p. 33–36 (in Russan).

Yudovich, Ya.E., Ketris, M.P., 2000. Osnovy litokhimii [Principles of Lithochemistry], Nauka

AC C

EP

TE D

Press, St. Petersburg. 450 p. (in Russian).

ACCEPTED MANUSCRIPT Captions for figures

Fig. 1. A map of the studied area showing the Bokhan site (the image is based on data of the Shuttle Radar Topographic Mission (SRTM).

RI PT

Fig. 2. Stratigraphic column (A) of the excavation (D) and location of the excavation at the Bokhan site (B, C).

Legend: 1 – silty clay; 2 – clayey loam; 3 – sandy gravel; 4 – molehill; 5 – carbonatization; 6 – ferruginization; 7 – modern soil; 8 – mammal bone. MIS – marine isotopic stages (Cohen,

SC

Gibbard, 2016).

M AN U

Fig. 3. Median values and range of values of elemental oxides, LOI and CO2 (А), rare and trace elements (B) in the sediments of the Bokhan section.

Fig. 4. Median values and range of values of the petrochemical indices in the sediments of the Bokhan section.

TE D

Fig. 5. Distribution of the geochemical indices along the depth profile. A: Variations of the pertochemical indices and pedogenic ratios. B: Variations of the geochemical proxies (Cu, Zn, LOI, Ba/Sr, Co/Zr, Cu/Zr). C: Variations of the weathering proxies and the relative temperature and humidity change (red lines), reconstructed using a complex of the geochemical data. The

EP

legend to the lithology column is shown on Fig. 2.)

AC C

Fig. 6. Pollen diagram of the Upper Neopleistocene sediments, Bokhan site.

Fig. 7. Pollen images from the Sartanian deposits (Upper Neopleistocene) of the Bokhan site. 1 – Abies; 2 – Picea; 3 – Pinus sect. Cembrae; 4, 5 – Pinus sylvestris; 6 – Betula sect. Albae; 7 – Chenopodiaceae; 8 – Asteraceae; 9 – Chicoriaceae; 10 – Cyperaceae, 11 – Fabaceae; 12 – Artemisia; 13 – Polypodiaceae – Polypodium; 14 – Diphasiastrum alpinum; 15 – Botrychium; 16 – Zygnema-type; 17 – Botryococcus; 18 – Cosmarium; 19 – Alternaria; 20 – Valsaria-type, 21 – Thecophora; 22 – Glomus.

Fig. 8. Molluscs found at the Bokhan site, Fore-Baikal region, Eastern Siberia, Russia.

ACCEPTED MANUSCRIPT

Legend: Succinella oblonga (Draparnaud, 1801): 1 – IG 345/5319/15, depth is 0.9–1.1 m; 2 – IG 345/5320/16, depth is 1.1–1.3 m; 3 – IG 345/5323/21, depth is 1.5–1.7 m; 4 – IG 345/5324/24, depth is 2.1–2.3 m; 5 – IG 345/5327/29, depth is 2.7–2.9 m; Pupilla muscorum (Linnaeus, 1758): 6 – IG 345/5323/22, depth is 1.5–1.7 m; Vallonia tenuilabris (A. Braun, 1843): 7 – IG 345/5317/11, depth is 0.5–0.7 m; 8 – IG 345/5318/12, depth is 0.7–0.9 m; 9 – IG 345/5323/20, depth is 1.5–1.7 m; 10 – IG 345/5324/23, depth is 2.1–2.3 m; 11 – IG 345/5325/25, depth is 2.1–

RI PT

2.3 m; 12 – IG 345/5326/28, depth is 2.3–2.5 m; Gyraulus laevis (Alder, 1838): 13 – IG 344/5316/7, layer 2; a – apertural view; b – abapertural view (view from the opposite side of the aperture); c – lateral view (top right); d – umbilical view; e – apical view.

SC

Fig. 9. Vole molars found in the Sartanian sediments of the Bokhan site, Fore-Baikal region, Eastern Siberia, Russia.

M AN U

Legend: 1 – Microtus gregalis Pallas, M1–M2, depth is 1.1–0.9 m; 2 – Lagurus lagurus Pallas, M1–M2, depth is 2.7–2.5 m; 3 – Microtus gregalis Pallas, M1, depth is 1.1–0.9 m; 4 – Microtus gregalis Pallas, M1–M2, depth is 1.1–0.9 m; 5 – Dicrostonyx cf. guilielmi Sanford M1, depth is 2.1–1.9 m; 6 – Lemmus amurensis Vinogradov M3, depth is 1.3–1.1 m; 7–8 – Dicrostonyx cf. guilielmi Sanford M2, depth is 2.1–1.9 m.

TE D

Fig. 10. The geographical position of the Late Pleistocene Bokhan site and Palaeolithic site Malta in the Baikal Siberia in frame of the recent ranges of Microtinae in Eurasia (according to Panteleev et al., 1990).

EP

Legend: 1 – Bokhan site, 2 – Palaeolithic site Malta.

AC C

Fig. 11. The summary data on the Bokhan site study

Captions for tables

Table 1. Petrochemical indices and pedogenic ratios.

Table 2. Molluscs species composition from the Sartanian horizon (MIS 2) of the Bokhan site. Legend: L3 –layer and its number.

Table 3. The stratigraphical distribution of the small mammals in the Bokhan site. Legend: 1/1 – Numbers indicate Minimum Number of individuals/ Number of Identified Specimens.

ACCEPTED MANUSCRIPT

Table 1. Petrochemical indices and pedogenic ratios

HM

TM

SM

Calculation

Proxy information

(Al2O3 +TiO2+Fe2O3+FeO+MnO) Hydrolizate index. Intensity SiO2 of chemical weathering Titanium index. Ti is most readily removed by TiO2 physical weathering, Al by Al2O3 chemical weathering. Acidification (provenance) Sodium index. Intensity of chemical weathering: degradation of plagioclases.

Na2O Al2O3

NAM

(Na2O+K2O) Al2O3

ASM

Al2O3 SiO2

A/CMKN

Al2О3/(СаО+Na2O+K2O+MgO)

(CaO+MgO) Al2O3

(CaO+MgO) Al2O3

Alkaline index. The ratio is a signal of the K-feldspar and mica content versus plagioclase content in the sediments. Normalized alkalinity index. Prevalence of feldspars. Provenance (presence of basic volcanic rocks,)-high values. Alumosilicic index. Degree of weathering. Clayeyness. Al accumulated as clay minerals form Common rock-forming alkaline and alkaline earth elements are lost relative to Al during pedogenesis The ratio reflects the accumulation of soil calcite and dolomite

Ba/Sr

Ba/Sr

Reference

Hydrolysis

Yudovich, Ketris,2000; Maslov, 2005;

Acidification

Yudovich, Ketris,2000; Maslov, 2005; Sheldon, 2006

Alkali elements accumulate as soluble salts not removed: salinization

Yudovich, Ketris,2000; Maslov, 2005; Retallack, 2007

Salinization

Yudovich, Ketris,2000; Maslov, 2005; Retallack, 2007

SC

M AN U

Salinization

Hydrolysis

Yudovich, Ketris,2000; Maslov, 2005; Retallack, 2001; Sheldon and Tabor, 2009 Yudovich, Ketris,2000; Maslov, 2005; Sheldon and Tabor, 2009

Hydrolysis

Retallack, 2007; Grazdankin, Maslov, 2012

Calcification

Retallack, 2007

Sr solubility >Ba solubility

Leaching, hydrolysis

Retallack, 2001; Sheldon and Tabor, 2009

The ratio reflects the sedimentation redox conditions. High values characterize oxidizing environment

Redox conditions

Kalinin et al,2009

TE D

(Fe2O3+MnO) Al2O3

AC C

(Fe2O3+MnO) Al2O3

Na2O K 2O

EP

AM

Pedogenic process

RI PT

Index

ACCEPTED MANUSCRIPT

Table 3. The stratigraphical distribution of the mammals in the Bokhan section

Taxa

Sartanian horizon (MIS 2) layer 1 layer 2 layer 3 3.0-2.0 m 2.0–0.9 m 0.9-0.5 m

Lagomorpha 1/1

RI PT

Ochotona sp. Rodentia Clethrionomys rutilus (Pallas, 1779)

1/1

Lemmus sibiricus (Kerr, 1792)

1/1

Dicrostonyx gulielmi Sanford, 1870

4/2

M AN U

Dicrostonyx sp.

1/1

SC

Lemmus amurensis Vinogradov, 1924

7/2

4/2

2/2

1/1

Lagurus lagurus (Pallas, 1773)

6/3

36/11

6/2

Microtus gregalis (Pallas, 1779)

6/2

25/12

8/6

M. hyperboreus Vinogradov, 1934

2/1

Microtus sp.

1/1

Alopex lagopus (Linnaeus, 1758)

+

TE D

Carnivora

+

Perissodactyla

Equus sp.

Coelodonta antiquitatis Blumenbach, 1799

+

EP

Artiodactyla

+

Bos sp.

+

AC C

Rangifer tarandus (Linnaeus, 1758)

Bison sp.

+ Proboscidea

Mammuthus primigenius Blumenbach, 1799

+

+

Legend: 1/1 – Numbers indicate Minimum Number of individuals/ Number of Identified Specimens.

ACCEPTED MANUSCRIPT Table 2. Molluscs species composition from the Sartanian horizon (MIS 2) of the Bokhan site Interval of depth of Sartanian horizon (MIS 2), m 0.5- 0.7- 0.9- 1.1- 1.3 1.3- 1.5- 1.9- 2.1- 2.3- 2.70.7 0.9 1.1 1.3 1.5 1.7 2.1 2.3 2.5 2.9 L3 L2 L2-1 L1 2017 2 3 3 3 6 22 5 4 1 2

1. Succinella oblonga (Draparnaud, 1801) 2. Succinea sp. 3. Vallonia tenuilabris (A. Braun, 1843) 1 4. Pupilla muscorum (Linnaeus, 1758) 5. Pupilla sp. 6. Gyraulus laevis (Alder, 1838) Shell fragments 3 Total 4

4

1

6

4

3

3

1 10

14 4

40

3

4

1

8

+ 8

2

AC C

EP

TE D

M AN U

SC

Legend: L3 – layer and its number.

3

Total 0.9-2.0 L2 2012 25 1 26 1 1 1

RI PT

Taxa

2

55

76 1 57 5 1 1 4 145

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT

AC C

EP

TE D

M AN U

SC

RI PT

ACCEPTED MANUSCRIPT