Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene

Abstract

The multi-layered settlement of Turganik in the Tok River valley (steppe region west of the Urals) has been studied using paleopedological and microbiomorphical methods. Early humans lived in the settlement during the Eneolithic epoch (the fifth millennium BC) and in the Early Bronze Age (the fourth millennium BC). The cultural layers attributable to the Atlantic period of the Holocene developed under conditions of a rather dry climate, with the landscapes being dominated by the grass and herb steppe. The settlement area was above the flood water level and was suitable for habitation. The soils in its vicinity were Kastanozems (Endosalic Protosodic). The final stages of the cultural layer formation bear traces of strong (though short-term) floods, with the deposits of the latter partly concealed traces of the preceding long-term arid phase. Maximum aridity was during the final interval of the Atlantic period. The Subboreal and Subatlantic periods were noted for meadow-chernozem soil formation (Luvic Chernozems [Stagnic]) and an increasing proportion of arboreal species in the pollen assemblages. Some phytoliths of aquatic plants were found in the assemblages dominated by those of meadow grasses. The climate was more humid and cool, although short episodes of aridity were possible.

Full text

Quaternary Research (2018), 1–15
Copyright © University of Washington. Published by Cambridge University Press, 2018.
doi:10.1017/qua.2018.23
Dynamics of paleoenvironments in the Cis-Ural steppes during the
mid- to late Holocene
Olga Khokhlova
a
*, Nina Morgunova
b
, Alexander Khokhlov
c
, Alexandra Golyeva
d
a
Institute of Physicochemical and Biological Problems in Soil Science, Russian Academy of Sciences, ul. Institutskaya 2, 142290, Pushchino, Moscow
Region, Russia
b
Orenburg State Pedagogical University, ul. Sovetskaya, 19, 460014, Orenburg, Russia
c
Insitute of Cell Biophysics, Russian Academy of Sciences, ul. Institutskaya 3, 142290, Pushchino, Moscow Region, Russia
d
Institute of Geography, Russian Academy of Sciences, Staromonetnyi pereulok, 29, 119017, Moscow, Russia
(RECEIVED August 23, 2017; ACCEPTED February 22, 2018)
Abstract
The multi-layered settlement of Turganik in the Tok River valley (steppe region west of the Urals) has been studied using
paleopedological and microbiomorphical methods. Early humans lived in the settlement during the Eneolithic epoch (the
fifth millennium BC) and in the Early Bronze Age (the fourth millennium BC). The cultural layers attributable to the
Atlantic period of the Holocene developed under conditions of a rather dry climate, with the landscapes being dominated
by the grass and herb steppe. The settlement area was above the flood water level and was suitable for habitation. The
soils in its vicinity were Kastanozems (Endosalic Protosodic). The final stages of the cultural layer formation bear traces
of strong (though short-term) floods, with the deposits of the latter partly concealed traces of the preceding long-term arid
phase. Maximum aridity was during the final interval of the Atlantic period. The Subboreal and Subatlantic periods were
noted for meadow-chernozem soil formation (Luvic Chernozems [Stagnic]) and an increasing proportion of arboreal
species in the pollen assemblages. Some phytoliths of aquatic plants were found in the assemblages dominated by those
of meadow grasses. The climate was more humid and cool, although short episodes of aridity were possible.
Keywords: Multi-layered settlement; Cultural layers; Paleopedological method; Microbiomorphical method; Phytoliths;
Paleoenvironmental reconstructions; Eneolithic; Early Bronze Age
INTRODUCTION
Paleosols buried under archaeological sites are natural
“archives”where information about past environments is
stored. The overwhelming majority of studies in archaeo-
logical pedology are focused on burial mounds (kurgans)
in Russia (Gennadiev, 1990; Ivanov, 1992; Demkin, 1997;
Dergacheva, 1997; Alexandrovskiy, 1996; Alexandrovskiy,
2000); while in Europe, the studies of this kind are less
common (Limbray, 1975; Goldberg and Macphail, 2006). In
the studies of paleosols buried under kurgans, the obtained
data on paleoenvironments characterize only a rather short
time interval immediately preceding the burial of the studied
paleosols. Studies of kurgans of different ages provided
materials for compiling a chronosequence of the buried soils
and for paleoenvironmental reconstructions covering a
longer time interval in the second half of the Holocene. The
cases of kurgan assemblages (cemeteries) confined to a lim-
ited area, with kurgans being raised successively through the
entire period of the kurgan ritual existence, from 6000 yr BP
to the early Middle Ages, are extremely rare (Morgunova
et al., 2003; Demkin et al., 2008; Pesochina, 2013). Even in
such cemeteries, there are considerable time intervals when
no kurgans were constructed. To fill the gaps—the time
intervals when kurgans were not constructed—we have to
interpolate the available data into the intervals lacking data
(Khokhlova et al., 2004).
There are known, however, earthen sites built by early
human (settlements) where material accumulated over a
considerable time interval (for instance, from the middle
Holocene to the present day). Though some sedimentary
layers may have been eroded at one time or another, still they
may still contain almost continuous records since the begin-
ning of the sites’existence (Sorokin, 2012). Such sites are of
special importance, as they shed light on the Holocene
intervals poorly represented in the paleosol sequences below
kurgans, in particular, the Atlantic period of the Holocene
*Corresponding author at: Institute of Physicochemical and Biological
Problems in Soil Science, Russian Academy of Sciences, ul. Institutskaya 2,
142290, Pushchino, Moscow Region, Russia. E-mail address: olga_004@
rambler.ru (O. Khokhlova).
1
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(7500–5000 yr BP). The kurgan rite arose in interfluves
of the Volga and Ural rivers rather late in the Atlantic period
(Merpert, 1974). Besides, kurgans dating back to such an
early age are exceedingly rare.
In the present study, the multi-layered Turganik settlement
in the Tok River valley (steppe area of the Cis-Urals,
Orenburg Region, Russia) was investigated using an inte-
grated (paleopedological and paleobotanical) approach. The
study is aimed at reconstructing paleoenvironmental
conditions, climate and vegetation in particular, for the entire
period of the settlement’s existence.
LOCATION AND SETTING
The Turganik settlement in the Orenburg Region constitutes
part of the so-called Ivanovo microregion of cultural heritage
monuments, along with the Mesolithic Starotokskaya site; an
Ivanovskoye multi-layered settlement (Neolithic, Eneolithic
[or Chalcolithic], Late Bronze Age); Toksky I and Toksky II
settlements attributed to the Late Bronze Age (the Timber-
Grave archaeological culture); an Ivanovsky ground burial
dated to the Eneolithic; and the Ivanovsky kurgan cemetery
of the Early Iron Age (Fig. 1).
The ancient settlements are located at the Turganik River
mouth, where the river joins the Tok River (the Samara River
drainage basin). The Turganik River enters an old channel of
the Tok which continues to flow due to that fact. Both valleys
are wide and dissected by multiple river channels. The
floodplain landscapes are mostly wet meadows with rich herb
and grass vegetation, pastures, and hay fields. On both sides
of the Turganik River, and farther along the right side of the
Tok valley there are flat-topped elevations, with occasional
forests (Chibilev, 1996). The Turganik settlement was posi-
tioned on a slightly elevated surface at the confluence of the
Turganik and Tok rivers, on the right side of the valley. The
settlement was inhabited in the Eneolithic and the Late
Bronze Age, the fifth to fourth millennia BC.
The studied area is at the extreme east of the East European
Platform, within the limits of Obshchiy Syrt Upland. The
latter is a kind of stepped structural surface with some
residual outliers of planation surface typical of the studied
region (the central Orenburg Region). The soil parent rocks
are the Quaternary loams and clays. Among the parent rocks,
there are some admixtures of red rocks attributed to the Tatar
Stage of the Permian System; that accounts for the brownish
or reddish hue of the soil horizons that developed in the
region.
The studied region belongs to the subzone of northern herb
and grass steppe with sheep’s fescue (Festuca sp.) and feather
grass (Stipa pennata) on Ordinary Chernozems (Erokhina,
1959) or on Calcic Chernozems (IUSS Working Group
WRB, 2014). The proportion of ploughed area is high (more
Figure 1. (color online) (a and b) Location of the studied region and (c) the objects of the cultural heritage in the microregion: 1, Turganik
settlement; 2, Toksky II settlement; 3, Ivanovsky dune with Ivanovsky ground cemetery; 4, Ivanovskoye II multi-layered settlement; 5,
Staro-Tokskaya site; 6, Toksky I settlement; 7, Ivanovsky I kurgan cemetery.
2O. Khokhlova et al.
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than 63%), while the percentage of forested land area is very
low and amounts to 0.7% at present. The climate is con-
tinental, with average long-term temperatures varying over a
wide range (about 15°C). The mean temperature is 21°C in
July and –15°C in January. Mean annual precipitation is 360
to 410 mm. The snow cover lasts for 145–150 days; its depth
at the end of winter is 30–40 mm. The frost-free period is
130 days long on average. The sum of temperatures above
10°Сexceeds 2600° С(Geographic atlas of Orenburg
Region, 1999).
MATERIALS AND METHODS
Archaeological excavations
The excavations of the site were performed in two stages. The
settlement was first excavated in 1981–1982, when cultural
layers were identified as belonging to the Eneolithic, Bronze
Age, and early Middle Ages. There was a dark-gray humus
horizon with pottery described above the lower Eneolithic
layer and tentatively assigned to the Early Bronze Age; its
cultural and chronological position was not determined con-
clusively due to its difference from previously known cul-
tures of that stage (Morgunova, 1984). Later on, after some
ceramic fragments had been radiocarbon dated, the cultural
remains were attributed to the Early Bronze Age (Morgu-
nova, 2014). Still, a few problems as to the ceramics chron-
ology and its cultural attribution remained unsolved. The
most serious doubts were raised in connection with the
radiocarbon ages being older than formerly accepted ages
(Kuznetsov, 2013). Thus, the excavations of the settlement
were resumed in 2014–2015. About 800 m
2
have been
excavated altogether (including the area opened in 1982).
The stratigraphy is uniform all over the area, as is the thick-
ness of cultural and barren layers. Six paleosol horizons have
been identified; the four upper ones, up to 60 cm thick, are
completely devoid of artifacts. The only exception is the
uppermost layer yielding some medieval pottery fragments.
The lower part of the sedimentary sequence appears to
include two cultural layers: the lower one contained pre-
dominantly Eneolithic ceramics, while the ceramic items
recovered from the upper layer are confidently attributed to the
Early Bronze Age. Judging from the morphological and
technological characteristics of the Eneolithic ceramics, they
were definitely related to the Samara culture (the second stage
in the evolution of the latter). That, together with the presence
of some objects directly imported from the Khvalynian culture
typical for the steppes in the Volga drainage basin, gave
grounds to correlate the layer with the Khvalynian culture
(Morgunova et al., 2016b). The data obtained from integrated
studies of the early Bronze ceramics confirmed its attribution
to the early (Repino) stage of the Pit-Grave culture
(Morgunova and Salugina, 2016; Morgunova et al., 2016a).
A series of 32 radiocarbon ages obtained on animal bones
and various ceramic fragments collected from all the exca-
vated areas and taken from different depths permitted the
cultural layers and related materials to be reliably dated
(Morgunova et al., 2016b). The ages formed three groups,
two of them falling within the Eneolithic epoch. The older of
the two (4898–4440 ВС) corresponds chronologically to the
Khvalynian burial grounds, the ceramics recovered from the
latter closely resembling those from the Turganik cultural
layer (Shishlina, 2007; Chernykh and Orlovskaya, 2010), as
well as the materials of the Khvalynian type found at the
settlements of the Samara region of the Volga drainage basin
(Korolev and Shalapinin, 2014). The second interval was
dated by radiocarbon to 4237–3790 ВС on samples of the
Toksky type ceramics (the late stage of the Samara culture).
The same stage is distinguished by the presence of Surtandy
and Novoilyinka type ceramics typical of the Transuralian
regions and the Kama drainage basin at that time. Both may
be assigned to the late stage of the Eneolithic epoch. The
cultural layer attributed to the Early Bronze Age was dated to
the interval of 3800–3360 BC, correlatable with the early
(Repion) stage of the Pit-Grave culture in the Cis-Ural steppe
(Morgunova, 2014).
Analysis of paleosols
The studies of paleosols were performed on the Turganik
settlement in 2015. The excavation wall was hidden under
50 cm layer of waste left by the previous excavations. The
wall was described in details, photographed, and sampled for
various kinds of analysis.
Analytical studies were performed at the Center of Com-
mon Facilities of the Institute of Physicochemical and Bio-
logical Problems in Soil Science, Pushchino, Russia. The
grain-size analysis for fine earth (<1 mm) was performed by
conventional pipette method with sodium pyrophosphate
pretreatment (Kachinskiy, 1965) to appropriate texture clas-
ses. Particle size distribution was established according to the
Russian conventional fraction groups, physical sand (fraction
>0.01 mm), physical clay (fraction <0.01 mm), and clay
(fraction <0.001 mm). The organic carbon content was
determined according to the Tyurin method of wet combus-
tion with potassium dichromate and concentrated sulfuric
acid. The carbonate CO
2
was determined by chromatography
in sealed vessels with rubber stoppers in which the samples
reacted with 10% HCl solution and were then converted to C.
The content of SO
4
gypsum was analyzed by weighing: the
method is based on the precipitation of the sulfate ion by
barium chloride, the weight of the calcined BaSO
4
precipitate
is recalculated to SO
4
. The sum of exchange bases was
determined by way of replacement with ammonium acetate,
K, and Na to be determined subsequently by flame-
photometer, and Ca and Mg by complexometry (Vorobieva,
1998). Soil acidity was determined in water extract (soil and
water are in a ratio of 1:5) and loss on ignition at 900°C
(Arinushkina, 1970).
The concentrations of macro- and microelements were
measured by the X-ray fluorescence analysis (XRF) using the
sequential (wavelength dispersive) vacuum spectrometer,
Axios mAX model, produced by PANalytical Company (the
Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene 3
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Netherlands, 2012). The macro- and microelements were
analyzed in the Laboratory of the Mineral Matter Analysis,
Institute of the Ore Geology, Petrography, Mineralogy, and
Geochemistry, Russian Academy of Sciences. The geo-
chemical coefficients were calculated from the data on the
bulk composition for every studied layer. Samples with
undisturbed structure were taken from every described layer
and thin sections were prepared. They were studied using a
polarized-light microscope (Carl Zeiss HBO 50, Germany) at
the Center of Common Facilities of the Institute of Physical,
Chemical and Biological Problems in Soil Science, Russian
Academy of Sciences located in Pushchino, Russia, and
described according to Stoop’s (2003) terminology.
Microbiomorphic analysis
Microbiomorphic analysis is the microscopic investigation of
detritus, phytoliths, sponge spicules, and other remains of
biota for the reconstruction of ancient pedogenic conditions.
Each microbiomorph is associated with certain types of land-
scape, and provides information on conditions of soil devel-
opment and on landscape evolution (Golyeva, 2001). The
main method of microbiomorphic analysis is the consecutive
study of individual kinds of biomorphs under the microscope.
The amount of 50 g of samples were treated with a hot 30%
solution of H
2
O
2
, separated from sand and clay, and subjected
to flotation in a heavy liquid (cadmium iodide and potassium
iodide with a specific gravity of about 2.3 g/cm
3
). After a
10-minute centrifugation, the floating siliceous and other
biomorphs were collected into a tube and washed with
distilled water several times, then immersed in oils (silica
oil or glycerin), and studied under the optical microscope at
200–900 × magnification. Quantitative content of silica
microbiomorphs was assessed following the methodology
published by Albert and colleagues (Albert and Weiner, 2001;
Albert et al., 2002). We counted all the morphotypes we found
per whole slide. Analyzing the entire complex of soil micro-
biomorphs enables one to determine the entire spectrum of
particles from one sample. Interpretation of the phytolith
assemblages in terms of ecology and environments is given
according to Golyeva (2007), who characterized phytolith
assemblages from different ecological zones of the Russian
Plain. In addition, the results of the microbiomorphic analysis
were compared with pollen analysis data obtained in the
1980s, when the Turganik site was first excavated (Lavrushin
and Spiridonova, 1995).
RESULTS
Profile description
The studied column was designated in the field as Tr1b-15
and included seven layers (Fig. 2). The column was described
from the top downward, with the boundary between the
buried surface and the overlying dumped soil being taken as
the initial point.
Layer I, 0–20 (22) cm or 50–70 (72) cm from the
dump surface (henceforth, the depths of layers are indicated
without regard for the dump thickness), is a medium loam
with granular structure, densely penetrated with roots,
and is gray-brown (10 YR 5/2) with a pale yellowish hue
(10YR 6/4).
Layer II, 20 (22)–50 (55) cm, is a very dark gray
(7.5 YR 3/1) medium loam with a coarse crumby
and granular structure; roots are less abundant compared
to layer I.
Layer III, 50 (55)–70 (80) cm, is dark gray with a brown
hue (7.5 YR 4/3) and very dense, with nutty structure easily
destroyed to dust under pressure; boundaries are quite indis-
tinct (due to appearance of carbonates in the lower part). The
presence of the carbonate efflorescence makes visible an
indistinct columnarity. Roots are rare and do not penetrate
into the lower layer.
Layer IV, 70 (80)–100 (105) cm, is dark gray with whitish
efflorescence of carbonates (10 YR 4/2). Stone rubble is
present in abundance and is traceable to the bottom. Both the
soil consistency and structure show columnar features, at
least in fragments; the deposits become more clayey
downward.
Layer V, 100 (105)–135 cm, is whitish due to abundant
carbonates (7.5 YR 6/3) and columnar structure is distinctly
seen when dried.
Layer VI, 135–150 (155) cm, is dark gray with a whitish
hue (10 YR 4/3), locally black with a hint of blue (10YR 2/1),
and poorer in carbonates. The structure is nutty-columnar and
easily crushed into small crumbs when scraped.
Layer VII, 150 (155)–180 (185) cm. The color abruptly
changes from dark gray to brown, with a reddish hue (2.5YR
4/6). There are holes of burrowing animals filled with dark
matter, the latter having a well-pronounced bluish hue. In
general, the material is structureless.
Figure 2. (color online) Morphology of the studied sequence,
Tr1b-15, and the position of the identified layers.
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Total phosphorus
As follows from the chemical analysis results, elevated con-
centrations of the total phosphorus (Р
2
О
5
) are found in layers
V and VI only. The phosphorus concentrations in those layers
are as high as 0.30%, while in the uppermost horizon (that
may be considered as background, or normal) and in all the
other layers they amount to 0.09-0.15% (Fig. 3a). Judging
from the distribution of that element, indicative of a human
impact (Leonardi, 1999; Holiday and Gartner, 2007), only
layers V and VI can be considered cultural layers, whereas
the remaining identified units are interpreted as natural
formations without human interference.
Organic and carbonate carbon
The distribution of the organic (C
org
) and carbonate carbon
(C
carb
) indicates that the deposition of C
org
definitely
exceeding that of C
carb
in layers I to IV (Fig. 3b), the carbo-
nates being completely absent from layers II and III. There-
fore, the upper part of the sequence, layers I–IV, developed
mostly in the absence of carbonates under conditions favor-
able to humus formation.
The cultural layers are characterized by slightly lower C
org
content when compared to the overlying horizons. The С
org
content presumably diminished after the soil burial due to
diagenetic biomineralization processes (Ivanov, 1992): the
longer a soil stays buried, the less humus it contains. To
compare the C
org
content in the studied layers, it is necessary
to take into consideration the fact that layers V and VI stayed
buried for a much longer time than the overlying layers, and
the diagenesis and decrease in the C
org
content proceeded
longer in them. Therefore, it should be admitted that the C
org
content in the cultural layers is not very low and could be
formerly comparable with (or even exceed) its content in
layers III–IV at the moment of the burial of the cultural layer.
The cultural layers display a higher proportion of C
carb
in
comparison with C
org
content (Fig. 3b, layers V, VI). That is
not particularly surprising, taking into consideration that C
org
loss is expected in deposits that have been buried for a long
time. It should be stressed that the carbonate content in cul-
tural layers is four to five times higher than in the overlying
layer IV, the latter being also carbonate-bearing. Finally,
layer VII may be considered to be essentially lithogenic
(parent rock), it is completely devoid of C
org
and features the
maximum concentration of C
carb
(up to 5%, i.e., more than
40% of the total mass of the material in terms of CaCO
3
). The
reddish hue noticeable in layer VII suggests solid calcareous
red rocks of the Tatarian stage (Permian) to take part (or are
predominant) in the layer formation.
Only the uppermost layer I shows the carbonate con-
centration increasing due to warming and summer droughts
recorded by instrumental meteorological observations over
the last decades (Platova, 2008). It is not inconceivable that
the uppermost layer I in the studied area was formed partly of
redeposited carbonate-enriched horizons of soils from the
vicinities. The surface soils of the vicinities are Haplic
qGypsic Calcisols (Endosalic, Sodic).
Particle-size distribution
As follows from the granulometric analysis (Fig. 3c), the
uppermost layer is of medium loam, layer II is fine loam,
layers III and IV are composed of silty clay, and layer VII is
of fine loam in common with layer II. As for the clay
Figure 3. (color online) The distribution of soil characteristics over the studied layers of the Tr1b-15 sequence: (a) total Р
2
О
5
,%; (b) C
org
and C
carb
, %; (c) fractions <0.001 mm and <0.01 mm, %; (d) pH
water
; (e) loss on ignition, %; (f) SO
4
of gypsum, %.
Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene 5
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proportion (light gray stripes in Fig. 3c), it is the greatest
(up to 40%) in the cultural layers V and VI.
Soil pH (H
2
O)
The obtained values of pH in the water extract vary from 7.8
to 8.6, that is, between weakly alkaline (рН =7–8) and
alkaline (рН =8–9) values (Fig. 3d). The values thus
obtained are correlatable with data on the carbon content,
both organic and carbonate. The least alkalinity (рН =7.8)
was recorded in layer II, noted for the highest content of C
org
and total absence of carbonates. The cultural layers V and VI
show the highest рН (8.5–8.6).
Loss on ignition
The loss on ignition was found as the difference of the soil
sample weight before and after heating to 900°C with free
access to air. The loss under those conditions includes che-
mically bound water, humus, CO
2
of carbonates, adsorbed
gases, and chlorides (Arinushkina, 1970). Maximum losses
on ignition were recorded in layers V and VII (Fig. 3e), which
is in good agreement with the highest proportion of carbo-
nates in those layers.
Gypsum content
Layers II and III are noted for the absence of gypsum, which
cannot be detected by the chemical analyses (Fig. 3f). The
maximum concentrations of gypsum are recorded in the
lower part of the studied sequence, in the lowermost layer VII
in particular, which may be attributed to the gypsum presence
in abundance in the parent (Permian) rocks. It is worth noting,
however, that gypsum content is only slightly lower in the
cultural layers.
Exchangeable bases
The studied layers differ notably from each other in the
composition and proportion of the exchangeable bases.
Exchangeable Ca is dominant in the two upper layers, which
are completely devoid of exchangeable Mg. The latter first
appears in layer III, its proportion is 15–16% in layers III and
IV, and reaches its maximum in the cultural layers and in
layer VII (up to 28%; Fig. 4). According to data in the
literature (Mikhailichenko et al., 1972; Slavnyy and
Mel’nikova, 1977), the exchangeable Mg in common with
the exchangeable Na may be the cause of the soil solonetzi-
city. In the considered case, the most important point is
a difference in the exchangeable base composition between
the modern upper layers (I, II) and the older, lower ones
(III–VII), with the cultural layers being of particular interest.
The modern layers are practically depleted of solonetzicity
(except for rare cases attributable to the presence a very small
quantity of Na), while the exchangeable Mg may be mostly
responsible for the solonets properties in the lower layers.
Geochemical indices
Geochemical indices based on bulk composition and on
ratios of macro- and microelements in soil mass (Nesbitt and
Young, 1982; Gallet et al. 1996; Retallack, 2001; Pieter et al.
2004; Driese et al. 2005; Starr and Lindroos, 2006; Whitfield
et al. 2006) can be divided into several groups. The first one
includes the following known as indices of weathering
(Fig. 5):
(a) СIA (chemical index of alteration) is calculated by the
formula CIA =[Al
2
O
3
/(Al
2
O
3
+ CaO + Na
2
O+K
2
O)] ×
100; it shows a relationship between primary and
secondary minerals in the bulk composition.
(b) Al
2
O
3
/(CaO + Na
2
O+K
2
O + MgO) displays clay con-
stituent relationship to the major cations removed into
soil solutions.
(c) Rb/Sr is the relation of micas and feldspars (with which
Rb is associated) to the carbonates associated with Sr.
(d) Ba/Sr is essentially close to the preceding index, except
Ba is only associated with feldspars.
(e) SiO
2
/(MnO + CaO + K
2
O+MgO+Na
2
O) characterizes
the eluviations processes.
The above-listed (first) group of the indices of weathering
characterizes the processes of leaching and hydrolysis. The
result of these processes is that certain chemical compounds
are dissolved and removed, while others remain fixed in the
soil profile. As follows from the data obtained (Fig. 5a–e), the
weathering indices in cultural layers (V–VI) are extremely
low when compared with the lowest values of layer VII
(slightly weathered parent rock). The weathering indices
calculated for layers I–IV show the maximum values,
especially in layers II and III.
The only index included into the second group, Zr/TiO
2
,
makes it possible to estimate the homogeneity of the material
constituting the layers (Retallack, 2001; Schilman et al.,
2001). Noteworthy is that the greatest values of the considered
index are observed in layers I and II (Fig. 5f). The distribution
of that coefficient over the layers suggests the two upper layers
contain an admixture of some material different in composi-
tion from the lower layers. This conclusion is in agreement
with the earlier conclusion regarding the exchangeable Na and
Mg distribution in the layers under study.
Indices СаО + MgO/Al
2
O
3
and Na
2
O/K
2
O form the third
group and point to the processes of enrichment in carbonates
Figure 4. (color online) Distribution of the exchangeable bases
over the studied sequence Tr1b-15.
6O. Khokhlova et al.
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and salinization (with readily soluble salts). The distribution
of the carbonate content index (Fig. 5g) correlates well with
the C
carb
distribution over the studied layers (Fig. 3b). This
supports the validity of usage of the geochemical index for
estimating process of carbonate accumulation. As for the
salinity index (Fig. 5h), the readily soluble salts prevail in the
lowermost and upper layers (VII and I) as could be expected,
as those layers are notable for the greatest proportion of
exchangeable Na (Fig. 4). The cultural layers VI and V are
also rich in the easily soluble salts. This agrees well with the
distribution of losses on ignition. It may be tentatively
ascribed to the chloride salt presence in the layers, though
they have not been specially analyzed. The “grayish”hue was
most characteristic of the cultural layers in particular. It
should be kept in mind, however, that the hue may be related
not only to a high proportion of carbonates, but to the pre-
sence of readily soluble salts (Fig. 2).
The indices attributed to the fourth group are related in one
way or another to the redistribution of iron and manganese
compounds (Fig. 5i–l). According to the published data (Vlag
et al., 2004), these indices are indicative of the level of
bioactivity and biological productivity in the sedimentary
rocks. We also placed the magnetic susceptibility (MS) of the
rocks in this group, as its value depends directly on the pre-
sence of iron-containing magnetic minerals, which may be
produced by micro-organisms under certain conditions
(Schüler and Frankel, 1999).
The highest values of the above-cited indices are found in the
cultural layers (Fig. 5i–k), and slightly lower values are found
in layers IV and VII. The measured magnetic susceptibility
values agree with those data (Fig. 5lm). That seems to be at
variance with the cited characteristics indicative of a greater
carbonate content and salinity in the cultural layers; the data
suggest a greater aridity at the time of the deposition of layers,
so that the freshly deposited material was hardly subject to
physical and chemical weathering in situ. On the other hand,
the layers are greatly enriched with Mn and Fe compounds and
magnetic minerals, which attest to a high level of bioactivity
and bioproductivity and to a considerable supply of moisture to
the layers. The micromorphological studies of the layers in
section Tr1b-15 shed new light upon that contradiction.
Micromorphology
The general microstructure of all the layers under study is dis-
played in Figure 6. When considered in succession, the gradual
changes in the layer structure are well traceable: the upper
layers (I and II) present granular structure, coprogenic, with
distinct traces of mezofauna activities (Fig. 6a and b); down-
ward the structure is coarser and the soil mass becomes more
Figure 5. (color online) Distribution of the geochemical indices (a–l) and magnetic susceptibility, ×10
–6
m
3
/kg (m), over the studied layers
in the Tr1b-15 sequence.
Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene 7
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compact and closely packed, though individual granular
aggregates are still visible and traces of faunal activities are
discernible in layers III and IV (Fig.6c and d). Cultural layers V
and VI are noted for a drastic change in structure: the soil mass
is broken into blocks outlined with regular (subparallel) fissures
and cracks (Fig. 6e and f). Layer VII is completely structureless
and Fe-Mn dark spots are well-pronounced (Fig. 6g).
The elements of structure, and first of all carbonate
features, when considered in detail, reveal specific char-
acteristics giving an insight into the cause of conflicting data
obtained from the studies of the layer composition (see
above). The fine matter in layer I is clayey-ferruginous in
composition, with carbonate accumulations found in pores,
voids, and present as micrite concentrations around pores, or
as undifferentiated nodules. Occasional presence of shell
fragments of presumably aquatic mollusks (Fig. 7a) suggests
the river periodically flooded the layer. Soil fine material in
layers II and III is clayey-ferriferous in composition, weakly
anisotropic, optically oriented around skeletal particles, and
mottled with spots of iron compounds and small-size Fe
nodules (Fig. 7b and c). Such microstructure is typical of
medium (not superficial) horizons of Meadow Chernozems
(Stagnic Chernozems) with sufficient water supply; usually
such soils develop under conditions of a leaching water
regime. Carbonates are completely absent from layer II,
while in the lower layer (III) they are found in a small pro-
portion as limestone fragments in pores. The calcareous
material of the fragments is recrystallized, which agrees well
with meadow type of soil formation easily identifiable from
the morphology and composition of the two layers.
Considering microstructures of the lower lying layers IV, V,
VI (Fig. 7d–f), the microstructure is noted for much darker color
as compared with the three others considered above. The fine
materials in layers IV, V, and VI is clayey-calcareous, so that
carbonates are present in abundance. The carbonates with clay
are overlain with clayey-ferruginous material, as particularly
clear in Figures 7d and e. When viewed in reflected light, the
samples show the presence of organic matter and manganese,
besides Fe and clay, in the overlying material. Some fragments
of calcareous shells are also quite distinct in the overlying
material (Fig. 7e and f). Evidently, that was a case of two-phase
formation of the fine material in the layers under consideration:
the initial clayey-calcareous material was later overlain with
ferruginous-clayey matter with organics and manganese
admixture. The presence of mollusk shells suggests fluvial
deposits taking part in the overlying material formation.
Figure 6. (color online) The microstructure of the studied layers in
the Tr1b-15 sequence. See the text for explanations. All the
photographs were taken with plane polarized light (PPL) at the
same magnification, except for (e) and (g).
Figure 7. (color online) Elements of microstructure of the studied
layers in the Tr1b-15 sequence. See the text for explanations. All
the photographs were taken with cross polarized light (XPL).
8O. Khokhlova et al.
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The microstructure of layer VII does not reveal any signs
of soil formation; diversified carbonate features, from
recrystallized calcareous rubble to cryptocrystalline nodules
in fine material and large fragments of shells (Fig. 7g), are
conspicuous. The mineral skeleton of the layer is quite dif-
ferent from the overlying layers in both composition and the
size of fragments. That is indirect evidence that the Permian
red rocks noted for a high content of carbonates took an
active part in the formation of that layer.
Microbiomorpic analysis
The microbiomorphic analysis revealed a great amount of
plant detritus and amorphous organics present practically in
all the layers (except for the lowermost layer VII, where its
proportion is slightly lower); sponge spicules (Fig. 8a) are
also present in abundance (Table 1). Cultural layers V and VI
differ from the other layers by the greatest proportion of
charred wood detritus. The spicules recovered from the layers
have no signs of corrosion and their canals are not filled with
mud, so they have not been redeposited and their deposition
was apparently synchronous to the formation of the layers.
Similar, undamaged spicules are present, though in smaller
amounts, in layers I and VII. Samples from layers III and IV
yielded spicules only occasionally, the latter being partially
destroyed, with canals well-silted with redeposited older
sediments. In addition to spicules, the samples contained
diatom frustules (Fig. 8b). It is of interest that the diatom
distribution is close to that of spicules: diatoms are found in
those samples only where the spicules seem to be well-
preserved (like those in layers I, V, and VI). The
best-preserved diatom frustules were recovered from the
uppermost sample.
The greatest number of phytoliths was recorded in layer VI
(Table 2). The sample taken from the layer differs con-
spicuously in phytolith abundance from adjacent samples. It
may be suggested that the layer richest in phytoliths is a result
of superposition of the cultural layer characteristics on the
alluvial deposits. Another possible explanation is that a
human dwelling existed there with various herb and grasses,
or probably reed, used in its construction.
The number of phytoliths in layers V and IV is much less
(almost by an order of magnitude) than in layer VI. It is only
in samples from those three layers that the presence of steppe
gramineous plants (Fig. 8c) together with reed (Fig. 8d) and
sedge phytoliths was recorded, along with a considerable
proportion of meadow grasses (Fig. 8e).
The samples with minimum number of phytoliths (layers II
and III) are also noted for the absence of diatoms and a
scarcity of sponge spicules. It may be assumed that those
layers resulted from the movement of sediments on the slope,
phytoliths being probably involved in the movement only
occasionally. It is also possible that originally those layers did
not occur on the surface and were exposed after the overlying
layers had been removed by erosion. Layer I also features an
abundance of phytoliths, their assortment is close to that in
the cultural layers. A distinguishing feature of layer I is the
presence of coniferous phytoliths (besides that layer, con-
iferous phytoliths [Fig. 8 f] were found only in layer VII, their
abundance being there ever greater); those of reed or sedge
are completely absent.
Phytolith assemblages recovered from fluvial sediments or
from deposits of slope wash or those of intermittent streams
provide information on the regional vegetation. As follows
from those data, the region was dominated by forest and
meadow coenoses at all times; small amounts of steppe grass
phytoliths were found in layers IV, V, and VI only.
Pollen analysis, comparison with data obtained
from microbiomorpic analysis
Pollen analysis was performed on the Turganik site by
Spiridonova (Lavrushin and Spiridonova, 1995) during the
Figure 8. Different forms of silica microbiomorphs: (a) sponge
spicula; (b) diatom; (c) phytolith of stipa grasses; (d) phytolith of
reed; (e) phytolith of meadow grasses; and (f) phytolith of
coniferous.
Table 1. Comparative semi-quantitative contents of micro-
biomorphs. Estimated content of the microbiomorphs: + + +, high;
+ +, medium; +, low.
Sample
no. Detritus
Amorphous
organics
Sponge
spicules Diatoms Phytoliths
1 + + + + + + + Single + +
2++++++ ––+
3 + + + + + + Single –Single
4 + + + + + + Single –++
5 + + + + + + + Single + +
6 + + + + + + + Single + + +
7++++ +–+
Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene 9
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first excavation of the settlement. The radiocarbon ages were
widely used when interpreting the pollen assemblages. In case
a particular layer had not been dated by radiocarbon, its age
was conjectured on the basis of geological and paleogeo-
graphic correlations. To give one example, layer VII, extre-
mely deficient in pollen and spores and composed mostly of
solid rock fragments, was tentatively dated by the authors to
the final stage of the late glacial (Younger Dryas). After that,
the processes of erosion and denudation were dominant. Much
later, at the second part of the Atlantic period of the Holocene
(as was confirmed by radiocarbon dating of archeological
materials), the pollen assemblages suggest steppe vegetation
of herbs and grasses, or purely grass steppe, with small amount
of pine. This conclusion agrees with the data on phytoliths and
with the xeromorphic properties of paleosols dated to that time
(the earlier phase of the layer VI deposition).
Pollen assemblages of the Atlantic optimum ~ 5500 yr BP
indicate some increase in moisture supply and related affor-
estation of the floodplain (Lavrushin and Spiridonova, 1995). As
follows from our data, the site was abandoned at that time and
the no-longer-functioning cultural layer VI was gradually buried
under deposits of frequent floods. According to the
14
Cages
obtained on archeological materials, the age of layer VI (or the
second stage of the Eneolithic epoch on the Turganik settlement)
may be dated to 4237–3790 cal yr BC, that is, somewhat earlier
than the Holocene optimum suggested by palynologists.
Layer V shows another interval marked by increasing cli-
mate aridity and the dominance of grass steppes. As stated by
the above-cited authors, the climate at the time that layer V
was functioning was even dryer than during the formation of
layer VI. That is confirmed by our data on the layer V com-
position, was formed during early Pit-Grave culture (the
Early Bronze Age), in the range from 3800–3360 BC,
according to the dates obtained on archeological
materials (Morgunova et al., 2016b). As follows from the
above, the maximum of aridity coincided with the Atlantic
optimum. The above-cited authors (Lavrushin and
Spiridonova, 1995) obtained the age of 4250 ±200
14
Cyr
BP on humus from layer V; that date may be taken as the end
of the functioning of the layer and the beginning of its burial
under later deposits.
Later on, in the Subboreal interval, the authors noted a
cooling, development of meadow-chernozem soils or Luvic
Chernozems (Stagnic; IUSS Working Group WRB, 2014),
and proportion of arboreal pollen in the assemblages rising up
to 40%. Quite possibly, it was at that time that layers IV, III,
and II formed. The humus horizons of the soils, however,
developed at that time could be completely destroyed by
wind erosion activated during dry intervals.
Finally, there are interlayers in layer I indicative of a drastic
increase in aridity that probably took place in the Middle Ages;
occasional fragments of medieval pottery have been recovered
from the layer where pollen assemblages are dominated by
Chenopodiaceae with Artemisia and grasses, with some sedge
pollen near the top of the layer. Most likely, the layer I for-
mation was a complicated process, asmight be inferred from its
composition as well as from pollen and spore assemblages.
On the whole, there is certain compatibility between the
data obtained from the phytolith analysis and those from
pollen assemblages; both strongly suggest the dominance of
open landscapes (indicated by prevalence of meadow plant
communities) through the entire period of the deposition.
Varying relation between tree species and steppe (dry steppe)
grasses may be interpreted in terms of the climate aridity and
humidity. Each of the considered methods provides
additional information on the landscapes and vegetation, in
particular, that existed at the time of the deposition,
functioning, and burial of the layers under study.
DISCUSSION
The analysis of the geologic and geomorphic context of the
Turganik settlement performed during its initial excavations
led Yu.A. Lavrushin to the conclusion on the deluvial-
proluvial character of its deposits, despite the fact that the
settlement is located near the riverbed of the Тоk River
(Lavrushin and Spiridonova, 1995). The archeological
objects are enclosed into an apron composed of materials
Table 2. Distribution of siliceous microbiomorphs (counted/%) and diagnostic groups of phytoliths (%). Numbers
1 to 6 designate the diagnostic groups of phytoliths as follows: 1, herbs; 2, coniferous needles; 3, forest grasses;
4, meadow grasses; 5, steppe grasses (mostly Stipa sp.); 6, reed and sedges.
Diagnostic group of phytoliths
Sample Total Sponge spicules Diatoms Phytoliths 1 2 3 4 5 6
1 102
a
/100 16/16 4/4 82/80 71 2 11 15 1 –
2 23/100 ––23/100 100 –– –––
3 6/100 3/50 –3/50 100 –– –––
4 67/100 4/6 –63/94 68 –10 16 3 3
5 73/100 9/12 1/1 63/87 75 –13 813
6 410/100 10/2 1/
b
399/98 63 –52822
7 40/100 18/45 –22/55 68 9 5 18 ––
a
Number per gram (millions).
b
Particles found in amounts less than 1% of the total.
10 O. Khokhlova et al.
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brought by sheetwash or ephemeral streams from the adjacent
elevated surfaces to the base of the valley side. Deposits of the
settlement may be a source of information on environments
during the entire period of the accumulation of sediments. We
focused our attention precisely on the processes of sediment
accumulation together with the environments of accumulation,
considering the morphology and composition of the layers in
the Tr1b-15 section on the Turganik settlement.
Clear signs of human activities are found in two out of
seven layers of the studied section; those are layers V and VI,
noted for increased contents of total phosphorus as compared
with the background values. Only those units may be con-
sidered as cultural layers bearing strong evidence of human
permanent habitation, not just of a short-time stay. In case of
a short-term human stay, some artefacts could be probably
found, but changes in the chemical composition of deposits
(an increased content of phosphorus) are highly improbable.
Among distinctive features of the morphology of cultural
layers are: a whitish hue clearly pronounced in the deposit
color, a high carbonate content, clayey composition, and
columnar or nutty-columnar structure (Table 3). The cultural
layers display an abundance of carbonates and gypsum, the
greatest proportion of fine fractions (<0.001 and <0.01 mm)
in their granulometric composition, the dominance of Mg in
the exchangeable bases, and the highest values of pH, while
geochemical coefficients of weathering are relatively low.
Only those cultural layers indicate the presence of readily
dissolved salts. Of course, such properties as alkalization and
carbonatization may be partly attributed to the results of
human activity. That was noted, for instance, in the soils of
antique cities in comparison with virgin natural soils (Alex-
androvskiy et al., 2015). But the whole set of the listed char-
acteristics can be conditional on natural processes only and
suggests highly arid environments at the time of accumulation
of those layers and transformation by soil-forming processes.
The soils formed at that time were probably of chestnut type
(or Kastanozems [Endosalic Protosodic]; IUSS Working
Group WRB, 2014), bearing distinct traces of salinization and
solonetzicity. These conclusions are supported by the data on
phytoliths and pollen assemblages, the latter being clearly
indicative of the dominance of grass and herb steppes at the
time of functioning of the cultural layer.
At the same time, the cultural layers under consideration
feature high contents of C
org
, along with high values of
geochemical coefficients of bioactivity and bioproductivity
of the ecosystems, as well as magnetic susceptibility. As
follows from the micromorphological studies, the fine mate-
rial rich in Fe, Mn, organic matter, and shell fragments
overlies and conceals the clayey-calcareous material. The
phytolith assemblages recovered from the layers include
sponge spicules and diatom frustules.
The observed characteristics of the microstructure and
composition of layers V and VI (cultural layers) may be
interpreted as follows. The layers were supposedly formed in
the course of prolonged and quiet stages of the slow sedi-
mentation, the deposits being gradually changed by processes
of the arid soil formation. Every stage of the deposition ended
with an episode of catastrophic floods that left the poorly
sorted overlying material. Those episodes were short when
compared with long-lasting period of the site (or settlement)
existence near the quietly flowing river, where floods did not
occur even in spring. That accounts for an apparent contra-
diction in the composition of cultural layers V and VI: on one
hand, they contain carbonates and gypsum, readily soluble
salts, exchangeable Na and Mg, and, on the other, iron
compounds (including magnetic ferriferous minerals),
manganese, and organic carbon. So, the long-lasting dry
periods when cultural layers developed and were functioning
came to an end with catastrophic floods that could force
ancient people to leave the habitable area. The floods were
probably high-energy but short-term: they left only limited
amounts of non-sorted material enriched in the above-listed
constituents and could not completely conceal traces of arid
soil-forming processes.
The aforementioned interpretation is supported by the
diversity of phytolith assemblages retrieved from the cultural
layers. These assemblages contain phytoliths of forest,
meadow, and steppe grasses on one hand and indicators of
aqueous environments of deposition (such as sponge
spicules, diatoms, reed, and sedges) on the other. The main
body of a cultural layer could be formed in comparatively
arid environments but, at the final stages, the river water
bringing minor amounts of alluvial material flooded the site.
The earliest stages of the sequence formation were marked by
the presence of coniferous trees in the vegetation, which seem
to be gradually restored at present.
Layer IV, dated to the final Atlantic-early Subboreal
periods of the Holocene, is similar to the cultural layers
(V and VI) in its composition and assortment of phytoliths.
This means that the processes of accumulation and transfor-
mation of materials in layer IV were largely similar to those
in the older cultural units. A more thorough analysis of layer
IV, however, revealed signs of a long-lasting increase in
humidity since the Subboreal period. When compared with
layers V–VI, layer IV is noted for a less distinct columnar
structure and a less pronounced whitish (grayish) hue in its
color. Traces of mesofauna activities are more noticeable in
micromorphology and granular aggregates appear. The C
org
accumulation prevails markedly over that of C
carb
, while the
pH of water extract and gypsum content are lower. Layer IV
is also noted for a higher proportion of exchangeable Ca in
the exchangeable bases, as well as for greater indices of
weathering and lower rate of carbonate accumulation and
salinity. The coefficients of biological activity and biopro-
ductivity as well as the value of magnetic susceptibility are
the highest in this layer (Table 3).
For reconstruction of environments at the second half of
the Holocene recorded in the studied layers, most important is
a dramatic change in the soil formation process after the
formation of layer IV had been completed. Unlike the lower
ones, layers II and III display characteristics of humid soil
formation: they are devoid of carbonates, gypsum, and easily
soluble salts, C
org
content is rather high, and the exchangeable
bases differ from the above in that Mg is completely absent or
Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene 11
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Table 3. The age of the layers, main indices of soil processes, pollen and phytolith assemblages, and paleoclimatic reconstruction.
Signs of ancient
Main indices of soil processes
Data on phytolith and
Soil name
according to Reconstructed
Layer Age human inhabitation Morphological Chemical pollen assemblages WRB-2014 climate
I Subatlantic period of
Holocene
Occasional
fragments of
medieval pottery
The lightest gray color Low percentage of C
carb
and
gypsum, a negligible
amounts of exchangeable
Na in the exchangeable
bases
Chenopodiaceae pollen
dominance (with
sagebrush and grasses
as co-dominants) in the
lower part of the layer
replaced by sedges in
the upper part of the
layer; the presence of
coniferous phytoliths
Haplic Gypsic
Calcisols
(Endosalic,
Sodic)
Comparatively
drier than
previously
II Subboreal period of
Holocene
No Well-pronounced signs of
biological activities and
soil aggregation: clear
granular structure; the iron-
clayey carbonate-free fine
material bears
characteristics of mobility
and anisotropy
No carbonates, gypsum, and
easily soluble salts; the
high C
org
content; the high
proportion of exchangeable
Ca and negligible amounts
of exchangeable Mg in the
exchangeable bases
Meadow forbs and herbs Luvic Chernozem
(Stagnic)
Humid
III
IV The final Atlantic –
early Subboreal
periods of the
Holocene
No Less distinct columnar
structure, traces of
mesofauna activities, an
appearance of granular
aggregates, a less
pronounced whitish
(grayish) hue
The C
org
accumulation
prevails over that of C
carb
;
lower pH and gypsum
content; higher proportion
of exchangeable Mg in the
exchangeable bases;
greater coefficients of
weathering and lower –
those of carbonate
accumulation and salinity;
highest coefficients of
biological activity and
bioproductivity; and the
highest magnetic
susceptibility
Steppe gramineous plants
together with reed and
sedge phytoliths; a
considerable proportion
of meadow grasses
Transitional soil
process from
Kastanozems
under dry steppe
to Luvic
Chernozems
under meadow
grasses
Transitional from
arid to humid
V 3800–3360 yrs cal BC Cultural layer of the
Repino stage of
the Pit-Grave
culture (the Early
Bronze Age)
Whitish hue in the deposit
color; columnar or nutty-
columnar structure
High carbonate and gypsum
percentages; the greatest
proportion of fine fractions
(<0.001 mm and <0.01
mm); the dominance of Mg
The dominance of grass
and herb steppes; the
greatest proportion of
charred wood detritus
Kastanozems
(Endosalic
Protosodic)
The most arid
12 O. Khokhlova et al.
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present in negligible amounts. Those layers show well-
pronounced signs of biological activities and soil aggrega-
tion: granular structure is clearly discernible in macro- and
micromorphology and the iron-clayey carbonate-free fine
material bears characteristics of mobility and anisotropy. All
those features are evidence of humid soil formation of the
meadow-chernozem type (or Luvic Chernozems [Stagnic];
IUSS Working Group WRB, 2014) in the case under con-
sideration. Frequent floods regularly occurring since then
made the high floodplain surface unfit for habitation.
Layer I seemingly developed at the time of the surrounding
area being actively used as arable land. The tilling caused
accelerated erosion. The layer composition gives an inte-
grated picture of the modern background soils resulting from
mixing of the upper humus horizons with the underlying
calcareous ones. Layer I is noted for the lightest gray color
(Table 3). As follows from the palynological data, the lower
interlayers within the layer contain information on a short
interval of increased aridity marked by Chenopodiaceae
pollen dominance (with sagebrush and grasses as codomi-
nants), replaced by sedges in the upper part of the layer.
It follows from the above that the Atlantic period of the
Holocene was mostly characterized by arid environments; the
peak of aridity fell on the early Bronze Age, the time of the
early (Repino) stage of the Yamnaya culture in the Cis-Ural
steppes. The Subboreal and Subatlantic periods were
relatively colder and more humid, though short episodes of
aridity could occur and some of them happened to be
recorded in the sequence under study.
The reconstructed history of the climate changes in the
Cis-Ural steppes during three intervals of the Holocene is in a
good agreement with the results obtained in other regions.
According to Alexandrovskiy (1996, 2000; Alexandrovskiy
et al., 1999, 2004), the Atlantic period was the most arid one in
the south of Russia, the subsequent intervals being compara-
tively wetter and colder. The extreme aridity was recorded on
the Ukraine territory at the final Atlantic period, a few less arid
chrono-intervals having been identified over the entire period
(Kotova, 2009). There are, however, other schemes of climate
fluctuations in the central part of the Russian steppe zone; a
few of them consider the Atlantic period to be humid, or even
the most humid, as compared with the second half of the
Holocene (Ivanov, 1992; Demkin, 1997). Also acceptable is a
scenario of climatic fluctuations occurring at different times in
different regions (Chendev et al., 2010). Further investigations
and accumulation of empirical data would help to gain a better
insight into the problem.
CONCLUSION
The studies of the multi-layered settlement Turganik (Cis-Ural
steppe region) permitted the development of a scheme of cli-
matic fluctuations and changes in regional vegetation for the
second half of the Holocene (beginning from the Atlantic); the
scheme is based on the data on paleosols and phytolith analysis,
some earlier publications on pollen assemblages also being
widely used.
Table 3. (Continued )
Signs of ancient
Main indices of soil processes
Data on phytolith and
Soil name
according to Reconstructed
Layer Age human inhabitation Morphological Chemical pollen assemblages WRB-2014 climate
in the exchangeable bases;
the highest values of pH;
low geochemical
coefficients; the presence of
readily dissolved salts
VI 4237–3790 yrs cal
ВС-upper part
4898–4440 yrs cal
ВС –lower part
Cultural layer of the
Khvalynian
culture (the
Eneolithic epoch)
Arid
VII The final stage of the
Late Glacial
(Younger Dryas)
No The reddish hue in the deposit
color is due to a high
proportion of solid
calcareous red rocks of the
Tatarian stage (Permian)
The highest proportion of
carbonates and absence of
C
org
; maximum losses on
ignition and gypsum
content
The presence of
coniferous phytoliths
No signs of soil
formation, the
predominance of
processes of
erosion and
denudation
Not reconstructed
Dynamics of paleoenvironments in the Cis-Ural steppes during the mid- to late Holocene 13
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The ancient people inhabited the place from 5000 to 4000 BC
(actually throughout the Atlantic period), when the place was
not subjected to flooding. At the time of human habitation, the
climate was mostly arid. Paleosols of that time are attributable to
the Kastanozems (Endosalic Protosodic). They developed under
grass (or herb and grass) steppes. The peak of aridity falls on the
final Atlantic period. At the end of Eneolithic epoch (the fifth
millennium BC) and in the Early Bronze Age (the fourth mil-
lennium BC) there were short-term but violent floods, which
forced people to leave the habitable place.
During the Subboreal and Subatlantic periods of the
Holocene, the climate became more humid, the floods
became regular, the vegetation was dominated by meadow
forbs and herbs growing on meadow-chernozem soils (Luvic
Chernozem [Stagnic]), and the settlement was completely
abandoned. In general, the studied sedimentary record at the
Turganik archeological site reveals traceable climate change
towards lower temperatures and increasing humidity in the
second part of the Holocene, with occasional episodes of
aridity that did not affect the general trend.
ACKNOWLEDGMENTS
The archeological excavations and dating were performed with the
financial support from the Department of Education and Science RF,
Project No 33.1389.2017. The paleosol investigations were funded
by the RSF, Project No 16-17-10280; the works on phytolith ana-
lysis had supported from the RSF Project No 14-27-00133. We also
thank two anonymous reviewers for their constructive criticism of
the manuscript and their valuable suggestions.
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