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Past climate and vegetation in Southeast Bulgaria — a study based on the late Miocene pollen record from the Tundzha Basin

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The results of palynological studies on the late Miocene freshwater deposits of the Tundzha Basin (Southeast Bulgaria, SE Europe) are presented. The basin is relatively well known in terms of geology and palaeogeography. The age of sediments in the Tundzha Basin ranges between the late Miocene to the Pliocene, based on mammal and diatom fossils. We carried out a palynological analysis of clayey sediments interlayered with coal beds from four cores and from one outcrop, aiming to obtain information about the composition and the structure of fossil vegetation. The ratios between the main floristic elements and the composition of the fossil flora are analysed and discussed from a palaeoecological point of view. Several main vegetation palaeocommunities were recorded: swamp forests, mixed mesophytic, communities of aquatic plants, and herbaceous palaeocoenoses. The changes in vegetation and in plant diversity are identified. The palaeoclimate analysis indicates a warm temperature climate with high rainfall and mild winter temperatures, without seasonal drier conditions. The early Pontian climate was about 3–4 °C warmer than today, with rainfalls per year at least 300 mm higher than today. The results of palaeoecological analysis of the flora and of the quantitative palaeoclimate data show that the climate in the Southeast Bulgaria indicates a climate change towards slight cooling and some drying. This event is consistent with the period of accumulation of the upper, undivided part of the Elhovo Formation.
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R E S E A R C H Open Access
Past climate and vegetation in Southeast
Bulgaria a study based on the late
Miocene pollen record from the Tundzha
Basin
Dimiter Ivanov
*
and Maria Lazarova
Abstract
The results of palynological studies on the late Miocene freshwater deposits of the Tundzha Basin (Southeast
Bulgaria, SE Europe) are presented. The basin is relatively well known in terms of geology and palaeogeography.
The age of sediments in the Tundzha Basin ranges between the late Miocene to the Pliocene, based on mammal
and diatom fossils. We carried out a palynological analysis of clayey sediments interlayered with coal beds from
four cores and from one outcrop, aiming to obtain information about the composition and the structure of fossil
vegetation. The ratios between the main floristic elements and the composition of the fossil flora are analysed and
discussed from a palaeoecological point of view. Several main vegetation palaeocommunities were recorded:
swamp forests, mixed mesophytic, communities of aquatic plants, and herbaceous palaeocoenoses. The changes in
vegetation and in plant diversity are identified. The palaeoclimate analysis indicates a warm temperature climate
with high rainfall and mild winter temperatures, without seasonal drier conditions. The early Pontian climate was
about 34 °C warmer than today, with rainfalls per year at least 300 mm higher than today. The results of
palaeoecological analysis of the flora and of the quantitative palaeoclimate data show that the climate in the
Southeast Bulgaria indicates a climate change towards slight cooling and some drying. This event is consistent with
the period of accumulation of the upper, undivided part of the Elhovo Formation.
Keywords: Palynology, Palaeobotany, Coexistence approach, Neogene, Tundzha Basin, Bulgaria
1 Introduction
Changes in climate and vegetation during the Miocene are
the subject of scientific interest which has encouraged
studies of fossil floras and palaeoenvironments. After the
middle Miocene climatic optimum (MMCO), the Earth
climate recorded a progressive cooling trend (Zachos et al.
2001). This reveals a global transformation in biodiversity
and ecosystems. For the eastern Paratethys, the emergence
of open habitats and the distribution of herbaceous vege-
tation during the late Miocene characterized the flora and
the vegetation turnover (Ivanov et al. 2002,2007c). The
territory of the Balkan Peninsula with its numerous Mio-
cene lakes and swamps served as a key region for the
study of the Neogene evolution of flora and vegetation, for
the migration routes and for the exchange corridor of
many plant species between Central-Eastern Europe and
Asia Minor (Meulenkamp et al. 1996;Rögl1998,1999;
Meulenkamp and Sissingh 2003; Popov et al. 2006;Akgün
et al. 2007; Akkiraz et al. 2008;Ivanovetal.2011;Alçiçek
and Jiménez-Moreno 2013;Biltekinetal.2015; Durak and
Akkiraz 2016; Ivanov and Worobiec 2017; Kayseri-Özer
2017; Kayseri-Özer et al. 2017; Yavuz et al. 2017). The ter-
ritory of Bulgaria apparently provides substantial informa-
tion for many of these processes, e.g., the survival of a
number of palaeotropical species in various refuges
and the processes of plant speciation (Palamarev 1989;
Palamarev and Ivanov 1998,2001,2004; Palamarev et al.
1999;Ivanov2015).
The spatial distribution of plants and vegetation strongly
depends on climatic conditions. Thus, through recon-
struction of the vegetation from the past, conclusions can
* Correspondence: dimiter@bio.bas.bg
Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of
Sciences, 23 Acad. G. Bonchev Str., BG-1113 Sofia, Bulgaria
Journal o
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Palaeo
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© The Author(s). 2019 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0
International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and
reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to
the Creative Commons license, and indicate if changes were made.
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3
https://doi.org/10.1186/s42501-018-0019-x
be drawn about past climates. Based on this assump-
tion, several quantitative methods have been developed
during the last few decades aiming to reconstruct the
climate of the past, e.g., the Climate Leaf Analysis Multi-
variate Programme (CLAMP) (Wolfe 1993), the Coexist-
ence Approach (CA) (Mosbrugger and Utescher 1997;
Utescher et al. 2014), the Leaf Margin Analysis (Wilf 1997),
the Climatic Amplitude Method (Fauquette et al. 1998),
and the European Leaf Physiognomic Approach (ELPA)
(Traiser et al. 2005). In this way, many climate reconstruc-
tions and a number of local and regional climatic recon-
structions have been proposed for the Neogene period
(Bertini 2002,2006; Bruch and Gabrielyan 2002;Ivanovet
al. 2002,2007c,2007b,2007a,2011; Bruch and Kovar-Eder
2003; Fauquette and Bertini 2003;Uhletal.2003,2006,
2007b,2007a; Bruch et al. 2004,2006,2007,2011;Mos-
brugger et al. 2005; Traiser et al. 2005,2007; Fauquette et
al. 2006,2007; Jiménez-Moreno 2006; Jiménez-Moreno and
Suc 2007; Jiménez-Moreno et al. 2007c,2007a,2007b,
2008a,2008b,2009;Utescheretal.2007,2009b,2009a,
2011a,2011b,2013,2015; Alçiçek and Jiménez-Moreno
2013;Ivanov2015; Ivanov and Worobiec 2017;Yavuzet
al. 2017).
Intensive investigations on the Miocene vegetation and
on climate dynamics were performed in the Neogene
basins in Bulgaria over the last years, using pollen ana-
lysis (e.g., Utescher et al. 2009b;Ivanovetal.2010,
2011; Hristova and Ivanov 2014;Ivanov2015;Ivanov
and Worobiec 2017). This area plays a key role in the
network of palaeoecological studies conducted in different
parts of the Balkan Peninsula in relation to Southeast-
European Neogene vegetation and flora history, aiming to
reveal the chronological succession of the main vegetation
phases, the climate changes behind them, species migra-
tion and distribution (Akgün et al. 2007;Jiménez-Moreno
et al. 2007c,2007a; Akkiraz et al. 2008; Bozukov et al.
2009; Alçiçek and Jiménez-Moreno 2013;Biltekinetal.
2015;Ivanov2015; Durak and Akkiraz 2016; Kayser-
i-Özer 2017; Kayseri-Özer et al. 2017; Yavuz et al.
2017). Nevertheless, there are only few studies in the
Fig. 1 Geological map of the Toundzha Basin, Southeast Bulgaria (redrawn from Kojumdgieva et al. 1984)
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 2 of 25
Southeast Bulgaria on past vegetation and climate
(Palamarev and Bozukov 2004;IvanovandLazarova
2005;Ivanovetal.2007b;Ivanov2004,2010). The aim
of this paper is to present new results on pollen analysis
from sediments of the Tundzha Basin and to
summarize the available data about the vegetation ecol-
ogy and climate in this area during the late Miocene.
2 Geology and palaeogeography
The Tundzha Basin provides important information on
both dynamics of the system of fresh-water basins on
Balkan Peninsula (Burchfiel et al. 2000; Nakov et al. 2001)
and climate change and vegetation evolution in southeast-
ern part of Europe (Ivanov et al. 2007b,2010). It occurs in
the Southeast Bulgaria (Fig. 1) and in older papers it is
also known as the Elhovo-Yambol Basin (Kojumdgieva et
al. 1984). The basin has a graben structure, which was
generated as a result of movements along faults during
the Tortonian (early late Miocene).
The Neogene sediments of the Tundzha Basin are
assigned to the Elhovo Formation (Kojumdgieva et al.
1984)withtwomembers(Fig.1): the Izgrev Member and
the Duganovo Member, and one undivided part (Prustnik
Limestone Formation; access to Angelova et al. 1991). It is
represented by an irregular alternation of claystone, sand-
stone and rare conglomerates. The thickness of the Elhovo
Formation is ca. 150200 m, but locally it reaches up to
300 m. Within these deposits, large lenses of gray and
black clays, diatomite clays and lignites are grouped within
the Izgrev Member, which locally occurs in the middle
part of the basin (Fig. 1). The total thickness of the Izgrev
Member reaches up to 40 m, with three main coal seams,
each of them with a thickness varying from 3 m up to 8 m.
The lignite seams accumulated in a rheotrophic, low-
lying mire. A vegetation rich in decay resistant conifers
dominated in the Elhovo Formation together with meso-
phytic angiosperm species. The peat accumulation oc-
curred in an environment subject to a low subsidence
rate, in which the woods were sustained severe mechan-
ical destruction prior to the burial. Peat accumulation
was terminated by a major flooding event, expressed by
a short-lived lake (Zdravkov et al. 2007). The Elhovo
Formation is unconformably overlain by a few meters of
the Pleistocene-Holocene sediments.
The vertebrate fauna recorded to the upper part of the
Elhovo Formation (Kojumdgieva et al. 1984; Nikolov
1985) reveals a Pontian (=late Messinian)-Pliocene age
(MN 1314). The results of the diatom analysis (Tem-
niskova-Topalova et al. 1996; Temniskova-Topalova and
Ognjanova-umenova 1997) confirmed the late Miocene
age (Pontian age for Elhovo Formation). The lithological
and facies characters and the specific cyclicity of the
sediments of the Tundzha Basin gave grounds to some
authors to define these sediments as analogous to the
Neogene sediments of the Upper Thracian Basin
(Dragomanov et al. 1984). However, similar correlations
were confirmed neither by biostratigraphic data, nor by
detailed sedimentological studies. Even more, significant
differences occur in the nature of sedimentation processes
in the two basins, with specific periods of sedimentation
interruption and denudation surfaces.
The sediments of the Elhovo Formation are deposited
in alluvial, fluvial and locally lacustrine-marshy environ-
ments (Nakov et al. 2001). As a result of extensive tec-
tonic movements at the beginning of the late Miocene, a
number of freshwater pools appeared in the Balkans,
including the Tundzha Basin. During the Maeotian, two
low areas were formed: Yambol and Elhovo (Savov
1983). The initial alluvial sedimentation had been pre-
dominantly replaced by lake and swamp environments
(Izgrev Member). Gradually, the basin was filled, and at
the end of the Pontian and the early Pliocene, the allu-
vial sedimentation was restored.
3 Material and methods
3.1 Studied sections
Fossil material has been collected and studied from four
cores in the central part of the Tundzha Basin: C-96,
C-146, C-127 and С-432 (Figs. 1and 2). The outcrops of
the Neogene sediments of the Tundzha Basin are very
scarce and they expose only the topmost intervals with
sands and sandstones. The drilled cores in the area pro-
vide the best material for studies and analyses. A basic
profile of the present study is the core C-432, near the
village of Trankovo, north of the town of Elhovo (Fig. 1).
This profile crosses the sediments of the Izgrev Member
of the Elhovo Formation. Samples of black and greyish
clays, lignite clays and diatomaceous clays are analyzed.
The total thickness of the studied profile is about 40 m.
In addition, materials from the other three cores located
north-northwest of the town of Elhovo, close to the core
C-432, were analyzed, namely cores C-96, C-146 and
C-127 (Figs. 1and 2).
Twenty-eight samples from the upper part of the
Elhovo Formation from three outcrops were collected
for pollen and spores analyses: 1) the outcrop in the
abandoned quarry in Prastnitsata, 200 m west of the
Izgrev village, Elhovo district (Kojumdgieva et al. 1984),
including about 1.5 m greenish clayey alleurites with
limestone and green muds, 67 m white and yellowish
fine-grained sands with layers of medium to coarse grain
sands (six samples); 2) the outcrop along the road from
Elhovo to Golyam Manastir village (SR-1), close to the
bridge over the Sinapovska River (18 samples); and, 3)
the outcrop Hanovo on the right bank of the Tundzha
River between the Hanovo and Tenevo villages, includ-
ing cross-bedding sands with thin layers of sandy clays
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 3 of 25
(four samples). Samples of these outcrops proved to be
barren, except for some of the samples of the outcrop
SR-1 (Sinapovska River outcrop).
The profile near Sinapovska River (SR-1) includes
about 5 m of sandstones with three layers of about 0.5 m
of green to purple aleuritic clays, followed by 510 m of
cross-bedded sands (for details see Ivanov et al. 2007a).
Leaf imprints and pollen have been found in the clay
layers. The sedimentological analysis of the flora-bearing
sediments (Ivanov et al. 2007a) explains the conditions
for the accummulation of sediments and for the preser-
vation of the fossil material. Good preservation of plant
debris is related to the relatively rapid sedimentation
(accumulation) rate of the alluvial clay material in which
they were deposited. This material underwent significant
compaction due to the pressure of the overlying sediments.
But the high sedimentation rate is inappropriate for the ac-
cumulation of sufficient pollen, which is why the estab-
lished pollen complexes are comparatively pure.
The total number of studied samples from the
Tundzha Basin is 64: 27 were barren, but 35 from four
cores and two from the outcrop SR-1 contained enough
pollen for study.
Tracing the changes in the percentage values of the
different pollen type curves permitted the identification
of pollen zones in the investigated cores. Differentiation
of the pollen zones is based on sediments with a specified
fossil content, or specific palaeontological characters (char-
acteristic pollen complexes, type and frequency of palyno-
morphs), which distinguish them from the neighbouring
sediments (Gordon and Birks 1972). The presented pollen
zones for each core were regarded as Local Pollen Zones
Fig. 2 Lithological columns of the studied cores C-432, C-96, C-127, C-146. For completing the lithological column of outcrop SR-1 is given.
Standard chronostratigraphy and regional stages were after Gradstein et al. (2004,2012)
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 4 of 25
(LPZ) indexed by letters and digits. The palynological sub-
division was applied only for the core C-432, which con-
tains enough samples for correlation.
3.2 Methods for vegetation and climate reconstructions
The principles of autecology were used for the recon-
struction of vegetation, as well as the data on eco-
logical requirements of the nearest analogues of the
fossil taxa. As many Neogene European floras, the flora
of the Tundhza Basin includes taxa whose nearest liv-
ing relatives (NLR) now grow in distant areas, e.g., East
Asia and North America. The palaeocoenoses were
reconstructed with the help of autecological analysis,
assuming that the ecological requirements of fossil taxa
are similar to those of their recent analogues; taxa with
similar ecological and edaphic requirements were grouped
and the main palaeocommunities were identified.
Charts showing the results of the pollen analyses are
illustrated by two types of pollen diagrams: detailed and
synthetic. The first diagrams include all identified plants
and show their individual presence. In the second type of
diagrams, the plants were ordered into ecological groups
following Suc (1984) and Jiménez-Moreno et al. (2005)
and they provide information for the general trends in
Fig. 3 aSpore-pollen percentage diagram of core C-432, Tundzha Basin (part a); bSpore-pollen percentage diagram of core C-432, Tundzha
Basin (part b)
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 5 of 25
vegetation change. The synthetic pollen diagram was plot-
ted with pollen taxa arranged in different groups on the
basis of ecological criteria to clearly show the temporal
changes in vegetation.
The groups used are the following (Nix 1982):
Mega-mesothermic (subtropical) elements: taxodioid
Cupressaceae pollen, Taxodium-type, Symplocos,Engel
hardia,Platycarya,Myrica, Sapotaceae, Distylium,Ha
mamelis,Corylopsis,Castanea-Castanopsis type, Cyrilla
ceae-Clethraceae, Reevesia, Theaceae, Alangium,
Chloranthaceae, Parthenocissus, Araliaceae, Arecaceae
and others;
Cathaya: pollen of Cathaya sp.;
Mesothermic elements: (Quercus,Carya,Pterocarya,
Carpinus betulus,Carpinus orientalis,Ostrya,Parrotia,
Eucommia,Juglans,Zelkova,Ulmus,Tilia,Acer,Liquid
ambar,Alnus,Salix,Populus,Rhus,Celtis,Platanus,
Nyssa,Ilex,Lonicera, Caprifoliaceae, Vitaceae, Fraxinus,
Betula,Sequoia-type, Fagus,Hedera,Ilex,Tilia, etc.;
Pinus + Pinaceae:Pinus diploxylon type and
undetermined Pinaceae pollen;
Mid-altitude trees (Meso-microthermic elements):
Tsuga,Cedrus,Sciadopitys;
High-altitude trees (microthermic elements): Abies,
Picea,Keteleeria;
Cupressaceae:Cupressus-Juniperus-type and/or pollen
irrespective of environmental interpretations, including
unspecified pollen grains;
Xerophytes: xerophyte taxa e.g. Quercus ilex-coccifera-
type, Olea-type (Oleaceae), Caesalpiniaceae, Pistacia,
Rhus and others;
Herbs: Poaceae, Amaranthaceae, Asteraceae-Asteroid
eae, Asteraceae-Cichorioideae, Centaurea,Plantago,
Brassicaceae, Lamiaceae, Valerianaceae, Polygonaceae,
Knautia (Dipsacoideae), Rosaceae, Malvaceae, Geran
iaceae, Erodium, Caryophyllaceae, etc.;
Steppe elements:Artemisia,Ephedra.
The palaeoclimate reconstructions in this work are
based on the Coexistence Approach (CA) (Mosbrug-
ger and Utescher 1997;Utescheretal.2014), and
based on the assumption that climatic requirements of
the fossil plants for environmental conditions are
similar to those of their recent analogues. It should be
noted that the Coexistence Approach uses only the
presence or absence of taxa, without analyzing their
relative frequency. Tests have shown that the ap-
proach yields good results when applied to fossil floras
with more than ten taxa with a known contemporary
analogue. The approach is valid for various types of
fossils: leaves, fruits and seeds, spores and pollen
grains. This method permits to analyze also carpologi-
cal data and to compare the two types of fossil
associations. This method provides a robust palaeo-
climatic proxy although its reliability has been ques-
tioned by some authors (Grimm and Denk 2012;
Grimm et al. 2016). A lot of studies were undertaken
for testing different climate reconstruction methods
(CAMethod, LMA, CLAMP, ELPA, etc.), which em-
phasized some differences in the results when compar-
ing the CA and other proxies. But in most cases,
similar results were obtained (Bruch et al. 2002;Uhlet
al. 2003;Yangetal.2007; Jacques et al. 2011,2014;
Xing et al. 2012; Bondarenko et al. 2013). The results
are consistent with respect to global climate recon-
structions, and in general they are consistent with the
data obtained from a large variety of other proxies, for
example isotope geochemistry, small mammals or
other independent palaeoclimatic approaches.
The Palaeoflora Database (Utescher and Mosbrugger,
19902018) has been used for palaeoclimatic recon-
structions. The graphic presentations of palaeoclimate
results are illustrated by the respective figures, where the
coexistence intervals (CA-intervals) for each pollen
spectrum (=local pollen flora) are represented by four
parameters. Besides the respective CA-intervals, the
graphics also show a curve of the CA mean values. This
curve does not mean that these are the most probable
values (the values of the respective climate parameter
could remain within the boundaries of the range), but
they illustrate approximately the changeability of climate
and the dynamics of climate values over time (Pross et
al. 2000; Ivanov et al. 2002).
4 Results
4.1 Palynological subdivision of the Elhovo formation
Core C-432 (Fig. 3)
Local pollen zone Tu-1
Ulmus -Betula -Carya
Age: late Miocene.
Distribution: 79.061.0 m.
The core is marked by high values of the Ulmus pollen,
which is represented by values ranging mainly in the range
of 13%20% and with a maximum of 29.8% at 65.0 m. The
quantity of Carya pollen is 4%9%, which are the highest
values in the core. The Betula pollen is also represented
with higher values (3%5%) in this part of the profile.
Fagus is represented with higher values in the lower part
of the zone (3.9%7.4%), and is below 1% and marked by
a sharp drop in the upper part (interval 64.561.0 m).
Similar dynamics of the quantitative values are character-
istic for inaperturate pollen referred to Glyptostrobus
3%-6% at the base and a drop to about 1% in the upper
part. Carpinus orientalis/Ostrya type, Ericaceae, Nyssa,
Poaceae, Typha ,Sparganium and Tricolporopollenites
sibiricum are also registered with higher values. Pinus
diploxylon type is represented by constant values ranging
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 6 of 25
in narrow range between 17% and 20%, with single devia-
tions from them, e.g., 11.3% at 73.0 m or 26.1% at 74.0 m.
Cathaya has low values not exceeding 1.5%. The pollen of
herbs is low (less than 1%), with the exception of Poaceae,
Asteraceae, partially Amaranthaceae: Chenopodioideae.
Higher values for these three pollen types trigger higher
NAP (Non-Arboreal Pollen grains) values, reaching a per-
centage of 13.1%, which is the maximum for the entire
profile. Local elements also have a broader involvement in
the pollen spectrum of this zone, reaching maximum
value of 15.6% at 73.0 m.
Local pollen zone Tu-2
Engelhardia -Quercus -Fraxinus
Age: late Miocene.
Distribution: 60.046.0 m.
Quercus records higher values in this part of the profile.
While in the previous zone it is discovered in quantities of
about 2%, in this zone its values vary between 6% and
11%. The change in the Engelhardia is similar, after a rela-
tively poor presence in the Tu-1 zone (2%5%), the par-
ticipation rate increased to 8%10% and even 11.8%
(maximum value for the whole profile registered at 48m).
The most significant is the increase in the participation of
Fraxinus: it reaches up to 12%16% from 2%5%. Parallel
to this, Tsu ga values increase up to 4%, and also Corylop-
sis, but less pronounced. Oleaceae (up to 4.7%), Buxus (up
to 2.6%) and Pistacia (up to 1%) are shown at the top of
the higher-value zone. Platanus pollen is below 1% across
in the profile, but at 48.0 m it has a peak of 9.6%. At the
same depth (48.0 m), Alnus, whose pollen in the rest of
the profile has a constant participation of 1%2%, also
shows its maximum percentage. In the range of 48.046.0
m, the Myrica (up to 3.6%) and Salix (up to 6.3%) were re-
corded. Lower values in this zone are registered for
Betula,Fagus,Ulmus and Carya, which were predominant
in the previous zone. Pollen of herbaceous plants (NAP) is
also presented with lower values. The local elements with
reduced pollen spectra in this pollen zone are Typha and
Sparganium.Pinus pollen reaches a peak at 54.0m (45%),
followed by a decreasing trend. Cathaya,aswellasinthe
Tu-1 zone, is low at 1.0%1.5%.
The pollen diagrams of the cores C-96, C-127 and C-
146 are not divided into pollen zones due to the small
number of studied samples (four to six in each core).
The analysis of pollen content and the quantification of
fossil palynomorphs show a similarity to the local pollen
zone (LPZ) Tu-2 on core C-432. The major pollen types
found in the cores C-96, C-127 and C-146 are of similar
values in all pollen spectra. Quercus pollen records high
values ranging from 6% to 11%. In this respect, the prox-
imity to the quantitative coverage of this type of pollen
is almost identical to its participation in the LPZ Tu-2.
Ulmus has variable values, with about 2% in most sam-
ples up to a maximum of 12.5%. With similar values,
this type of pollen is recorded in the upper parts of the
LPZ Tu-2. Similar values are represented by Tsuga and
Picea, for which values of 1%2% were established in
four profiles. Similar quantities are observed in the
pollen of Betula,Fagus,Oleaceae,Pterocarya,Carya,
Engelhardia,Alnus,Salix, and Myrica ranging from 1%
2% to 3%4%.
The main differences in both profiles refer to Pinus
pollen. Pinus diploxylon-type in LPZ Tu-2 has a quan-
titative value close to the core C-96 (except the max-
imum at 54.0 m), followed by a decreasing trend
observed in both profiles. The more significant is the
presence of Cathaya,whichintheLPZTu-2waspre-
sented with lower values (1.0%1.5%), and only in the
pollen spectrum of 46.0 m was registered with higher
values (3.6%). In the core C-96, this type of pollen is
registered with higher values of 11%17%, which in
the upper part of the section reduced to 5%. Higher
values may be explained partly by local features in the
structure of vegetation, suggesting a greater involve-
ment of Cathaya in the pollen rain. Another possibil-
ity is related to a discrepancy in stratigraphic levels,
e.g., the cut-out interval from the core is a later stage
of the LPZ Tu-2, at the end of which higher values of
this pollen type were recorded. The lack of other fos-
sils, lithological and stratigraphic data makes the cor-
relation of the two cores less reliable.
The pollen flora from the Sinapovska Riveroutcrop
(SR-1) differs significantly from the flora found in the
sediments of the Izgrev Member of the Elhovo Forma-
tion. The profile includes layers of greenish to violet
aleuretic clays, which refer to the uppermost levels of
Elhovo Formation and correspond to a later stage in the
development of the flora in the area. A characteristic
feature of the pollen flora is the significant involvement
of pollen from herbaceous plants and the lack of repre-
sentatives of spore plants. Herbaceous plants are subject
to significant taxonomic diversity and to a high percent-
age participation, e.g., Amaranthaceae: Chenopodioideae
(11.6%), Asteroideae (8.5%), Poaceae (7.1%), Dipsacoi-
deae (Caprifoliaceae) (5.4%), and Artemisia (2.7%). The
composition of the spore-pollen complex differs signifi-
cantly from the pollen complexes of the studied samples
from cores C-432, C-96, C-127 and C-146. At the same
time, the low content of pollen in the studied samples
makes the separation of an independent pollen zone in
the outcrop Sinapovska River (SR-1) uncertain.
4.2 Fossil flora and vegetation of the Tundzha Basin
The pollen analysis of the sediments of the Tundzha
Basin (the Izgrev Member of the Elhovo Formarion and
the upper undivided part of the Elhovo Formation) re-
veals the characters and the peculiarities of the fossil
flora and vegetation during their accumulation. The total
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 7 of 25
composition of the fossil flora from four cores and the
outcrop SR-1 includes 114 taxa (Table 1; Plates 1,2and
3). The basic floristic diversity of the relatively rich
Tundzha palaeoflora is due to arboreal plants, a charac-
teristic feature of the late Miocene flora. They are repre-
sented by 87 taxa from 50 families (among them the tree
and shrub species predominate as 60 taxa, and the grasses
are 27 taxa), the Gymnosperms are registered with 16
pollen taxa, and the spores plants are with 12 species. The
Pinaceae pollen has the highest values among the trees,
with the Pinus diploxylon-type predominant in the cores
C-432, C-127 and C-146 and the Cathaya is more
frequent in the core C-96. Picea,Abies,Ts u ga,Cedrus,
Sequoia-type, and Cupressaceae (Cupressus-Juniperus-
type) are present in small amounts, usually less than 3%.
The families Fagaceae, Juglandaceae, Betulaceae, Aster-
aceae, Ulmaceae, Hamamelidaceae and Oleaceae are
present with higher diversity among angiosperms. Quer-
cus,Ulmus,Fraxinus,Fagus,Engelhardia and Carya are
the most abundant among them. The percentage of most
taxa varies within a relatively narrow range, mainly be-
tween 1%5%, and refers to Betula,Corylus,Carpinus,
Acer,Tilia ,Castanea-Castanopsis-type, Corylopsis,Eucom-
mia,Pterocarya and others.
The thermophillous elements are relatively limited in
the composition of the flora in terms of their floral diver-
sity. Grass plants are poorly represented in quantitative
terms, although they are covered with 27 taxa, which is
about a fifth of the palaeoflora diversity. The pollen of
wood and shrub components (AP) is predominant. This
implies the dominance of the forest-type vegetation in the
areas around the basin. This does not apply to the pollen
flora from the outcrop of Sinapovska River, where the
grass component is much better represented.
Table 1 Taxonomic composition of the fossil pollen flora from
the Tundzha Basin
Taxa Taxa
Abies sp. Lycopodium sp.
Acer sp. Magnolia sp.
Achillea sp. Mentha/Salvia
Alisma sp. Myrica sp.
Alnus sp. Nuphar sp.
Amaranthaceae: Chenopodioideae Nymphaeaceae
Anacardiaceae Nyssa sp.
Apiaceae Oleaceae
Araliaceae Osmunda sp.
Artemisia sp. Parrotia sp.
Aster type Persicaria sp.
Asteraceae Picea sp.
Asteraceae: Asteroideae Pinaceae indet.
Asteraceae: Cichorioideae Pinus diploxylon-type
Betula sp. Cathaya sp.
Brassicaceae Trifolium sp.
Buxus sp. Pistacia sp.
Caprifoliaceae: Caprifolioideae Plantaginaceae
Caprifoliaceae: Dipsacoideae Platanus sp.
Carpinus betulus type Platycarya sp.
Carpinus orientalis/Ostrya type Poaceae
Carya sp. 1 and sp. 2 Polygonum sp.
Caryophyllaceae Polypodiaceae
Castanea sp. Polypodiosporites sp.
Castanopsis sp. Potamogeton sp.
Cedrus sp. Pteridium sp.
Celtis sp. Pteridophyta
Centaurea sp. Pterocarya sp. 1 and sp. 2
cf. Altingia Quercus sp. 1 and sp. 2
cf. Glyptostrobus Ranunculaceae
Cornus sp. Rosaceae
Corrugatosporites sp. Rubiaceae
Corylopsis sp. Salix sp.
Corylus sp. Sapotaceae
Cupressaceae (Cupressus-Juniperus-type) Sciadopitys sp.
Cyperaceae Selaginella sp.
Cyrillaceae/Clethraceae Sequoia-type sp.
Echinatisporis sp. Sparganium sp.
Engelhardia sp. 1 and sp. 2 Symplocos sp.
Ephedra sp. Tamarix sp.
Equisetum sp. TaxodioidCupressaceae
cf. Euphorbia Thalictrum sp.
Ericaceae Tilia sp.
Table 1 Taxonomic composition of the fossil pollen flora from
the Tundzha Basin (Continued)
Taxa Taxa
Eucommia sp. Tricolporopollenites sibiricum
Fabaceae Tsuga canadensis-type
Fagus sp. Tsuga heterophylla-type
Fraxinus sp. Tsuga sp.
Hedera sp. Typha sp.
Humulus/Cannabis type Typha/Sparganium
Ilex sp. Ulmus sp.
Juglans sp. 1 and sp. 2 Urtica sp.
cf. Keteeleria Verrucatosporites sp.
Laevigatosporites Viburnum sp.
Liliaceae Vitaceae
Liquidambar sp. Zelkova sp.
Lonicera sp. Botryococcus sp.
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 8 of 25
Plate 1 (See legend on next page.)
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 9 of 25
An interesting feature of the palaeoflora is the morpho-
logical variability of the pollen of the Juglandaceae family,
observed in all recorded genera. In the case of genus
Engelhardia (Pl. 3: 19) the variability can be considered
within the range of the natural variation of the morpho-
logical features as it shows smooth transitions without dis-
tinct differences in grain outline and in morphometric
characteristics. This pollen type can be assumed to be
within the range of the variability of Engelhardia walli-
chiana-type (Ivanov 2004). The pollen illustrated on Pl.
310 and Pl. 311 is morphologically close to Engelhardia
spicata-type, and more specifically to the pollen of mod-
ern species of E. rigida Blume and E. spicata Blume.
Two morphotypes were found in the Carya pollen (Pl.
2: 2933), which differ in size of pollen grains and thick-
ness of the exine. The pollen of Pterocarya is also repre-
sented by two pollen types (Pl. 3: 14 and 15), with a
major difference between them in the shape of apertures
and in the exine thickness, the first closer to the modern
species Pterocarya pterocarpa (Michx.) Kunth. (Pl. 314)
and the second closer to Pterocarya serrata Schneider
(Pl. 315).
Exine thickness, pollen grain outlines and aperture shape
are the diagnostic characters allowing the separation of two
morphotypes in the fossil pollen of Juglans (Pl. 3: 12 and
13), corresponding to the artificial species Juglandipollis
juglandoides Kohlman-Adamska (Pl. 312) and Juglandi-
pollis maculosus (Pot.) Kohlman-Adamska (Pl. 313).
The palaeoflora from the outcrop SR-1 has a more
limited floristic composition, as the palynomorphs are
poorly preserved due to taphonomic reasons (see above
Chapter 4.1.). The high sedimentation rate at which fos-
sil deposition is formed explains the poor pollen content
of the recorded fossil complexes (Ivanov et al. 2007a).
The palaeobotanical studies on the composition of the
macroflora include mainly the results of the leaves from
the outcrop SR-1 (Palamarev and Bozukov 2004). The
macroflora is represented by 33 species belonging to 16
families. Scarce palaeofloristic data are also reported for
carpoids from the Elhovo Formation (including the
Izgrev Member) Potamogeton,Phelodendron,Polycne-
mum,Portulaca,Arenaria and Chenopodium (Pala-
marev 1990; Mai and Palamarev 1997). A total of 35
genera were found in the macroflora composition, and
11 of them were confirmed by palynomorphs. 64 species
are reported in the present study as new fossil taxa for
the studied area.
The data obtained from the four cores (Figs. 3,4,5
and 6) show that the mesophytic forest communities
played a key role in the formation of the natural vegeta-
tion cover in the studied area during the sediment de-
position of the Izgrev Member. Mixed mesophytic
forests occupied vast territories in the plain and in the
lowlands surrounding the basin. A dominant role in
their structure was played by representatives of Quer-
cus,Ulmus,Fraxinus,Fagus,Engelhardia and Carya.
The structure of the mesophytic forests was not con-
stant in time and space, and at certain stages, species of
different genera were dominant. This is emphasized by
the changes in the quantitative involvement of these
major pollen types in pollen records, due to the dynam-
ics of vegetation in time. The spatial differentiation of
vegetation and the prevalence of different plant types in
the areas along water bodies explain the differences in
quantitative values of the dominant taxa in the four
cores. From a taphonomic and palaeoecological point
of view, the mixed mesophytic forests inhabited a nat-
ural polytope complex, with a variety of lowland and
low hilly terrain, crossed by a complex river network
and marked by the presence of large lakes or swamps.
The composition of the mixed mesophytic forest com-
munities varied, and besides the families already men-
tioned, the representatives of Magnolia,Betula,Corylus,
Carpinus,Fagus,Acer,Tili a,Castanea,Corylopsis,Parro-
tia,Eucommia,Pterocarya,Juglans,Ilex,Buxus and others
participate in their structure. Thermophilous plant species
of the genera and families Platycarya,Engelhardia,Sym-
plocos, Sapotaceae, and Araliaceae are also present in
pollen spectra with varying frequencies in sediments of
different age and position. Of these, only the representa-
tives of the Engelhardia probably had a dominant role at
certain stages of vegetation development. The reasons for
such an assumption are provided by the data dealing with
quantitative values of this genus illustrated in Figs. 3,4,5
and 6.
The variegated palaeofloristic composition of mixed
mesophytic forest communities suggests the presence of
vertical differentiation of palaeoflora and of palaeocenoses
and the existence of a belt of mountain forest palaeoce-
noses. The components involved in the construction of
mountain palaeocenoses include representatives of the
genera Tsuga ,Abies,Keteleeria,Picea,Cedrus and Cath-
aya, generating mixed communities with the participation
of Betula,Fagus,Acer and Ericaceae.
(See figure on previous page.)
Plate 1 Selected spores and pollen from the late Neogene of the Tundzha Basin. 1, 2 Polypodiaceae/Thelypteridaceae (Laevigatosporites); 3, 4
Pteridaceae (Polypodiaceoisporites cf. gracillimus Nagy); 5, 6 Cathaya sp.; 7 Abies sp.; 8, 9 Tsuga sp.; 10, 11 Tsuga canadensis type;
12, 13 Tsuga heterophylla type; 14, 15 Betula sp.; 16, 17 Betula sp.; 18, 23, 24 Myrica sp.; 19, 20 Carpinus betulus type; 21, 22, 27
Corylus sp.; 25, 26 Carpinus orientalis type; 28, 29 - Ulmus sp. Scale bars = 10 μm
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 10 of 25
Plate 2 Selected spores and pollen from the late Neogene of the Tundzha Basin. 1 Ulmus sp.; 25Zelkova sp.; 6, 7 Eucommia sp.; 810
Quercus sp. 1; 11, 12 Quercus sp. 2; 1315 Quercus sp. 1 (Polar view); 16, 17 cf. Parrotia;1820 Fagus sp.; 21, 22 Liquidambar sp.; 23, 24
Salix sp. (Polar view); 25, 26 Cyrillaceae/Clethraceae; 27, 28 cf. Cyrillaceae; 29, 30 Carya sp. 1; 3133 Carya sp. 2. Scale bars = 10 μm
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 11 of 25
Plate 3 (See legend on next page.)
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 12 of 25
The vertical differentiation of vegetation has been
expressed in mountain systems located remote from the
Tundzha Basin. The low values of the representatives of
these communities (Figs. 3,4,5and 6) support such con-
clusions. This is particularly emphasized by the synthe-
sized pollen diagrams, where the meso-microthermal
groups (hill and low-mountain communities) and the
microthermal elements (involved in the structure of
high-mountain forest ecosystems) are presented at values
around and below 5% (Figs. 7,8,9and 10). These data
support the idea that in the region of present-day south-
eastern Bulgaria, which is predominantly flat and with low
mountains, the main mountain ecosystems were relatively
distant from the place of pollen deposition.
Herbaceous palaeocenoses have a relatively limited distri-
bution, demonstrated by low percentages of their pollen.
This indicates their limited importance for the formation of
the vegetation cover compared to the forest palaeocenoses.
Their main components were Amaranthaceae: Chenopo-
dioideae, Asteraceae, Caryophyllaceae, Apiaceae, Brassica-
ceae, Poaceae, Ranunculaceae, Achillea,Artemisia,Aster,
Centaurea,Mentha/Salvia,Polygonum, Plantaginaceae,
Thalictrum and others. Probably some of them have been
involved in the structure of herbs cover in the mesophytic
forest communities, while others have occupied open (or
erosional) terrains near the basin and the river valleys.
Swamp forests were comparatively limited, as evidenced
by the percentage contribution of their components to
pollen spectra. Representatives of Ta x o d io i d Cupressaceae
and Alnus were predominant in these forests, which are
supposed by the slightly higher pollen values found in
pollen spectra (1%2% to 5%7%). They were accompanied
by species belonging to the genera Glyptostrobus,Sciadop-
itys,Nyssa,Myrica,Osmunda,Salix, and Cyrillacaeae/Cle-
thraceae, typically represented at around 1%, rarely higher.
The presence of pollen from some pollen types characteris-
tic of coastal forests (e.g., Salix,Pterocarya,Platanus,Li-
quidambar, etc.) can be interpreted as an indication of the
distribution of this type of palaeocenoses in the valleys of
the inflowing rivers and in the coastal areas. Fraxinus,
which in some of the analyzed samples, was recorded with
high values compared to other taxa, probably also partici-
pated in the composition of riparian forests, swamps or
transitional areas with mixed mesophytic forest palaeoce-
noses. Components of these palaeocenoses were probably
the liana species of Vitaceae, Humulus and Hedera.
Thespreadofswampforestsislikelytobedirectlyre-
lated to the water level in the basin. During high water
stands of the lake, the diatomite clays wеre deposited, while
at low water stands, the marsh-swampy vegetation was
widespread, as precursors of coal seams. The Tundzha
Basin was an extensive graben structure formed in the final
stage of the continental collision at the southern edge of
the Alpine Orogen. Typically, this type of basins has a
similar development, starting with lake-river sedimentation
and deposition of conglomerates and sands, gradually
(See figure on previous page.)
Plate 3 Selected spores and pollen from the late Neogene of the Tundzha Basin. 19Engelhardia sp. (Morphological variability); 10, 11 Engelhardia
sp. (cf. Engelhardia spicata type); 12 Juglans sp.1(Juglandipollis juglandoides Kohlman-Adamska); 13 Juglans sp.2(Juglandipollis maculosus
(Pot.) Kohlman-Adamska); 14 Pterocarya sp. 1 (cf. Pterocarya pterocarpa (Michx.) Kunth.); 15 Pterocarya sp. 2 (cf. Pterocarya serrata
Schneider); 16 Lamiaceae; 17 Apiaceae; 18 Amaranthaceae: Chenopodioideae; 1921 cf. Euphorbia; 22, 23 Persicaria sp.; 24
Tricolporopollenites sp.; 25, 26 Poaceae; 27 Ericaceae; 28 Sparganium sp.; 29 Botryococcus sp.; 30, 31 Tricolporopollenites
sibiricum;32Bambusoideae (Poaceae). Scale bars = 10 μm
Fig. 4 Spore-pollen percentage diagram of core C-96, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 13 of 25
passing into clay sedimentation and subsequently swamp-
ing and forming thick coal beds covered by lake sediments
(Zdravkov et al. 2007). This sequence reflects the drown-
ing of the palaeomire due to high subsidence rates. When
subsidence rates decreased, the lake was filled with
river-delta sediments. The high number of lignite layers in
the Tundzha Basin is the evidence of a relatively low
subsidence speed, which allowed the frequent change be-
tween lacustrine (diatomaceous and black clays) and
swampy environments (lignite).. The high peat content of
lignite indicates that swamps were often flooded, and the
marsh complex was of the so-called rheolytic marshes
(Zdravkov et al. 2007).
The geochemical analysis of the coals showed that lig-
nites originated from coniferous wood, which is signifi-
cantly more resistant to oxidation processes than that of
herbaceous plants and it is better stored (Zdravkov et al.
2007). Probably the main coal precursors were the repre-
sentatives of Taxodioideae (Taxodium,Glyptostrobus), as
in most Miocene lignite basins in Bulgaria.
During the periods of peat accumulation, the (ground)-
water table was probably not above the peat surface. The
basis for such asumption is the complete absence of algal
remains and of sapropelic coal (Zdravkov et al. 2007). Ac-
cording to Zdravkov et al. (2007), the vegetation rich in
decay-resistant conifers, accompanied by mesophytic
broadleaf species, prevailed during these intervals. Due to
the lack of samples for pollen analysis from coal beds, this
assumption cannot be confirmed or rejected. The studied
samples were collected from diatomitic and black clays
formed in lake environments. The results of the diatom
analysis (Temniskova-Topalova et al. 1996)showthatdur-
ing the period of accumulation of diatomaceous clays, the
lake had a depth of approximatively 15.0 m. This means
that during high water stands in the Tundzha Basin, vast
territories flooded and the marshland had been completely
submerged. This explains the low participation of swamp
palaeocoenoses components, which have been preserved
on the outskirts of the lake complex, in conditions suitable
for their ecology.
Fig. 5 Spore-pollen percentage diagram of core C-127, Tundzha Basin
Fig. 6 Spore-pollen percentage diagram of core C-146, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 14 of 25
The representatives of aquatic vegetation (euhydro-
phyte and hygrohydrophyte grasslands) found in the
studied pollen spectra are in low quantities and they
have a relatively poor species composition. In the
open water, typical hydatophytes evolved, such as, in
Potamogeton,inNuphar, and in Nymphaeaceae. In
the peripheral areas of the basin, plant communities
of helophyite species of Alisma,Persicaria,Typ ha and
Sparganium were developed. The low occurrence of
pollen from aquatic plants in the pollen spectra sup-
ports the features of the lake basin: rather deep (pre-
dominant planktonic species of diatom algae), poorly
developed shallow water (suitable for the development
of hygrohydrophyte grasslands) and low eutrophicity
(Temniskova-Topalova et al. 1996).
The xerophytes (Oleaceae, Celtis,Rhus,Buxus,Pis-
tacia and some grasses) also have a limited distribu-
tion occupying possibly eroded or rocky terrains near
the lake. The development of this vegetation type
was directly related to edaphic and microclimatic fac-
tors. The quantitative contribution of sub-xerophytes
and xerophytes in pollen spectra does not give rea-
son to assume that they have the character of zonal
vegetation.
Fig. 7 Synthetic pollen diagram of core C-432, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 15 of 25
5 Climatic analysis of the fossil flora of Tundzha
Basin
The results of the palaeo-climatic analysis of the pollen
flora from the studied cores (C-432, C-96, C-127, C-146)
obtained using the Coexistence Approach are illustrated in
Figs. 11,12,13 and 14. The current climate in the Tundzha
Lowland, Southeast Bulgaria, is characterized by the follow-
ing climate parameters: the mean annual temperature
(MAT) 12.2 °C, the coldest month temperature (CMT) 0.9 °
C, the warmest month temperature (WMT) 22.7 °C, and
the mean annual precipitation (MAP) 541 mm according to
data from the Yambol meteorological station, located at
143 m above sea level (Stringmeteo 20062009;Velev
1997). For the Elhovo meteorological station (130 m above
sea level) the data show: MAT 12.3 °C, CMT 1.1 °C, WMT
22.9 °C, and MAP 545 mm.
The climate reconstruction, based on the palaeoeco-
logical data from the Izgrev Member of the Elhovo For-
mation, shows relatively constant values for observed
climate parameters. The lower limit of the coexistence
intervals for the mean annual temperature is limited in
all the analyzed pollen floras at 15.6 °C. The upper limit
is in most cases set at 16.5 °C, only in few cases higher
values (18.4 °C and 19.4 °C) are observed thus forming
Fig. 8 Synthetic pollen diagram of core C-96, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 16 of 25
wider ranges. The average temperature was typically
about 16 °C with few exceptions. These annual temper-
atures show the relatively high precision of results ob-
tained with the Coexistence Approach. The stability of
the data for these parameters and the absence of signifi-
cant deviations indicate no significant climate change.
Winter temperatures also show relatively constant
values without significant changes. The most common
coexistence intervals are 5.07.0 °C, and the most com-
mon mean values are 6.0 °C. In some cases, the upper
limit of calculated cold temperature values indicates
higher values and wider ranges, for example, 5.08.1 °C
and 5.09.6 °C. In the coldest month temperature, the
lower limit of intervals is important because low winter
temperatures are often a limiting factor for the spread
of many plants. The persistence of values above 5.0 °C
indicates a mild and wet winter without extreme mini-
mum temperatures.
Perhaps the wider ranges for the two temperature ra-
tios are related to the incomplete fossil record rather
Fig. 9 Synthetic pollen diagram of core C-127, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 17 of 25
than to a possible climate change. As far as they occur
almost in synchronicity in the analyzed pollen flora, a
slightly warmer climate with a higher average annual
temperature due to higher winter temperatures is not
excluded, with less seasonal climate change. The latter
assumption is supported by the results obtained for the
average temperature of the warmest month. The ob-
tained WMTs are 24.727.8 °C and 24.727.3 °C (with
one exception at 61 m; Fig. 11) and the average summer
temperatures are in the range of 26.026.3 °C. There is
no synchronization between wider WMT intervals and
the other two indicators CMT and MAT. This sug-
gests a less pronounced seasonality, related only to a
change in winter temperatures.
The mean annual precipitation also does not show
drastic deviations. The intervals for annual rainfall are
Fig. 10 Synthetic pollen diagram of core C-146, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 18 of 25
relatively broad ranging from 823 mm/m
2
to 1308 mm/
m
2
, and the average curve is slightly above 1000 mm.
6 Discussion
The dynamics of the pollen quantitative values of the
various fossil taxa showed two stages in vegetation de-
velopment, the boundary between them being estab-
lished in the pollen spectrum of 60.00 m in core C-432
(Fig. 3). The representatives of Ulmus and Carya dom-
inate the mesophytic forest communities of the lower
part of the profile (LPZ Tu-1). The representatives of
Betula,Fagus and Carpinus orientalis/Ostrya also
played an important role in the construction of this
type of palaeocoenosis. The mega-mesothermic ele-
ments (Figs. 7,8,9and 10) are represented with lower
values and the grasses have a wider distribution reach-
ing a maximum in the range of 64.562.5 m in core
C-432. Among the latter, a major role is played by spe-
cies belonging to the families Asteraceae, Poaceae, and
partially Amaranthaceae: Chenopodioideae. Hydro-
phytic forest palaeocenoses also had a wider spread,
and Glyptostrobus was dominant. The representatives
of the Nyssa were also important components of the
swamp forests. The hydrophytic herbaceous vegetation
represented by Typ ha and Sparganium has also been
established. These data testify to the development of
the flora in a warm temperate and humid climate.
In the range of 60.046.0 m (LPZ Tu-2) in core C-432
(Fig. 3), a significant change in the composition and struc-
ture of the vegetation was recorded. The change is associ-
ated with an increase in Quercus,Fraxinus,Engelhardia,
Oleaceae, Buxus, Cyperaceae, Typha,Sparganium and
NAP. An interesting fact is that in the diatom flora of core
C-432 changes also occur in this interval (Temniskova--
Topalova et al. 1996). It is likely that a climate change
took place. The beginning of this change is recorded to
the top of the profile C-432, and a later result of this
change is reflected in the flora from the outcrop SR-1 (see
below). The most significant change in the composition of
the mesophytic forest communities was a change of dom-
inant taxa a reduced distribution of Ulmus and Carya
is observed, and at the same time, a rapid increase in the
values of Quercus and Engelhardia. The participation of
Fraxinus pollen, which plays an important role in the
Fig. 11 Coexistence intervals (bars) for the mean annual temperature (MAT), and the coldest (CMT) and warmest month temperature (WMT), and
the mean annual precipitation (MAT) of core C-432, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 19 of 25
construction of riparian forest palaeocenoses, is stronger.
The participation of Oleaceae, Buxus and Pistacia in the
composition of the vegetation increases in the upper part
of the profile. Mega-mesothermic elements (Fig. 7)are
presented with higher values, which may indicate warm-
ing climate.
The profiles C-96, C-127 and C-146 show a trend to-
wards the reduction of coniferous pollen (Cathaya and
Pinus), but the group of mesothermal and subtropical
species does not change significantly (Figs. 4,5and 6).
This change can be correlated with that of the top of core
C-432, or it may even be a sequel. The increase in herb-
aceous pollen at the top of the cores C-96, C-127 and
C-146 (Figs. 4and 7) coincided with some increases in
NAP in C-432 and the increased participation of some
(sub-) xerophytes in the same range. These data could in-
dicate a certain climate change associated with increased
seasonality and the occurrence of drier habitats.
The pollen record from the outcrop SR-1 differs from
the four cores. It includes 47 taxa from 30 families (Iva-
nov et al. 2007a). The fossil macroflora (Palamarev and
Bozukov 2004) includes a total of 33 taxa of 16 families
of leaf imprints. Based on the composition of the estab-
lished macro- and micro-flora, the following main plant
communities are distinguished: mixed mesophytic for-
ests composed of representatives of Magnolia,Lindera,
Daphnogene,Ocotea,Quercus,Carya,Acer,Ulmus,Zel-
kova,Corylus,Fagus,Castanea,Tilia,Wisteria,etc.;
riparian forests involving species of the genera Salix,
Populus,Pterocarya,Liquidambar,Alnus,Rhamnus,
Nyssa,Myrica, and Bambusoideae; xero-mesophyte tree
and shrub communities of Robinia,Arbutus,Paliurus,
Pistacia,Parrotia, Oleaceae; herbaceous palaeocenoses
composited by the following families and genera: Amar-
anthaceae: Chenopodioideae, Asteraceae, Artemisia,
Centaurea, Plantaginaceae, Caryophyllaceae, Brassica-
ceae, Apiaceae, Poaceae, Dipsacoideae (Caprifoliaceae);
hydrophytic vegetation of Ty pha,Sparganium, Cypera-
ceae, Nymphaeaceae.
The representatives of the riparian forests are repre-
sented with the greatest number of leaf imprints. This is
related, on one hand, to the better storage possibilities
(spread around the water basin) and, on another hand,
to the relatively limited distribution of mesophytic forest
palaeocenoses. In spatial terms, mesophytic forests have
been in close contact with riparian and coastal forests,
occupying damp habitats in lowered areas of relief with-
out forming a fully developed mesophytic forest belt
Fig. 12 Coexistence intervals (bars) for the mean annual temperature (MAT), and the coldest (CMT) and warmest month temperature (WMT), and
the mean annual precipitation (MAT) of core C-96, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 20 of 25
(Ivanov et al. 2007a). Palynological data also suggest that
the mesophytic forests were fragmented, as their represen-
tatives have low values and low affinity in pollen spectra.
They differ significantly from the data on the mixed meso-
phytic forests that existed during the accumulation of the
sediments of the Izgrev Member, when they were building
the zonal vegetation. During this period of vegetation de-
velopment, Quercus and Ulmus were the dominants in
forest vegetation, with Betula,Carya,Carpinus,Corylus,
Acer,Juglans,Engelhardia,Tilia and others. The floristic
elements, whose distribution today is bound to temperate
climates, but also with some thermophillous taxa, are
regular in the pollen record of Engelhardia,Platycarya,
Castanea-Castanopsis,Corylopsis (see above). The pres-
ence of pollen from Pinus,Tsuga ,Cedrus,Keteleeria and
Picea implies the presence of mountain forest communi-
ties. Their low percentages suggest that the recorded
pollen is likely to be a result of a long distant transport, as
there were not enough high-mountain systems near the
sedimentation site. Xerophytes also played an important
role in shaping the palaeolandscape. Their representatives
were spread over drier and more eroded terrains, along
rocky slopes.
Pollen data suggest a wide spread of grass palaecoenosis
(NAP = 45.8%). It is quite possible the existence of at least
two types of herbaceous communities: mesophytic grass-
lands inhabiting humid habitats near ponds (wetland prai-
ries, wet prairies; see Hofmann and Zetter 2005), and
more xerophytic herbs spread over drier terrains. As some
recent studies on the prevalence of modern pollen and the
AP/NAP ratio to their vegetation produce (Favre et al.
2008), small changes in herbs pollen values usually do not
take into account real changes in herbaceous vegetation.
While the sharp change in the ratio of woody and grassy
pollen in favor of the latter is usually a sure indication of
open habitats. Palamarev et al. (1999) also testify to the
prevalence of xerophytic grasslands, made up of represen-
tatives of Polycnemum,Chenopodium,Arenaria and Por-
tulaca, who formed semi-grade species communities on
open and eroded terrains.
Popescu (2006) provided palaeoecological data from
the Southwest Black Sea Region (DSDP Site 380A) and
notedanincreaseinthegrasscomponentandthe
steppe/forest index (SFI) in the late Miocene-Pliocene.
These data correspond to the high NAP values found
in this study. A sharp increase and high values of the
grass component were also recorded for the upper
sequences of the late Miocene sediments of the Karlovo
and Staniantsi Basins (Utescher et al. 2009b;Ivanovet
al. 2010).
Fig. 13 Coexistence intervals (bars) for the mean annual temperature (MAT), and the coldest (CMT) and warmest month temperature (WMT), and
the mean annual precipitation (MAT) of core C-127, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 21 of 25
All palaeoclimatic data provided in the current study
indicate a warm to subtropical climate with values for all
temperatures of about 4 °C higher than today and with
precipitations that were at least 300 mm higher than
today. The climate was steady and stable over the period
of sedimentary deposition. This assumption of slight cli-
mate change to the top of the profile (LPZ Tu-2), based
on the analysis of vegetation changes, finds no confirm-
ation in the climate reconstructions. Perhaps such a
change was less than the resolution of the Coexistence
Approach, which explains why it was not registered in
other palaeoclimate reconstructions.
The climate reconstruction, based on the palaeo-floris-
tic data from outcrop SR-1,, shows different values for
the monitored parameters. The calculations made for
the ranges of the individual palaeoclimate values based
on the data from fossil macroflora (Ivanov et al. 2007a)
show that the annual temperatures were in the range of
14.415.8 °C, the winter temperatures were 3.75.8 °C,
the summer temperatures were 25.626.4 °C, and the
annual rainfall was in the range of 9611179 mm. These
values are several degrees higher than the current values
for the temperatures in the Elhovo-Yambol area, and sig-
nificantly higher in terms of the amount of precipitation.
Calculated values for the same climate parameters, based
on palynological data, show wider CA intervals: MAT as
13.618.4 °C, CMT as 2.49.4 °C, WMT as 22.826.1 °C,
and MAP as 7401206 mm. The wider coexistence in-
tervals derived from the palynological data are explained
by the lower taxonomic resolution of the pollen analysis.
The wider annual precipitation interval (7401206 mm)
may reflect also the diversity in the climatic conditions
of a larger area, and the presence of habitats with a drier
character.
The results of the macro- and micro-flora analysis
from outcrop SR-1 show a high degree of similarity,
which increases the reliability of the resulting palaeo-
climate quantification. They are also in line with the
palaeoecological analysis of the flora, which implies
the development of the vegetation in a temperate cli-
mate with a possible dry period in the year. Compared
to the results on palaeoclimate, during the deposition
of the Izgrev Member, a climate-cooling trend, which
is reflected in all temperature parameters, and a lower
amount of annual rainfall, is now reported.
7 Conclusions
The results from the pollen analysis of the Neogene
sediments from the Tundzha Basin include spore and
pollen flora permitting to outline the main vegetation
Fig. 14 Coexistence intervals (bars) for the mean annual temperature (MAT), and the coldest (CMT) and warmest month temperature (WMT), and
the mean annual precipitation (MAT) of core C-146, Tundzha Basin
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 22 of 25
palaeocommunities: namely mixed mesophytic forests,
swamp forests, communities of aquatic plants, and herb-
aceous palaeocoenoses. The dominant species in the zonal
vegetation were floristic elements growing in warmtemper-
ate to subtropical climate conditions, while thermophillous
floristic elements were not well represented. The studied
palaeoflora shows a stage in the long-term evolution of the
Late Neogene floras in the Balkan Peninsula, connected
with the reduction of palaeotropical elements, the domin-
ance of arcto-tertiary taxa in the vegetation structure, and
the increased distribution of herbaceous vegetation. Palaeo-
climate results obtained with the Coexistance Approach
show that the climate in the Tundzha Basin was warm tem-
perate and permanently humid.
The results from the palaeoecological analysis of the
flora and the quantitative data on the palaeoclimate re-
corded from the top of the sediment succession (the
outcrop SR-1) show a trend in climate change towards
the decline of temperature and of humiditity and a wider
distribution of herbaceous vegetation.
Abbreviations
AP: Arboreal Pollen grains; CA: Coexistence Approach; CAM: Climatic Amplitude
Method; CLAMP: Climate Leaf Analysis Multivariate Programme; ELPA: European
Leaf Physiognomic Approach.; LMA: Leaf Margin Analysis; NAP: Non-Arboreal
Pollen grains
Acknowledgements
The authors are grateful to V. Mosbrugger and T. Utescher (Germany) for the
kindly provided access to the Palaeoflora database and Climstat software
used by us for climate reconstructions. This work is a contribution to the
International Network Programe NECLIME (www.neclime.de) and Project B-
1525/2005 NSF of Bulgaria. The authors are thankfull for the critical reading
and the valuable comments of three anonymous peer-reviewers.
Authorscontributions
DI carried out pollen analysis of core C-432, ML carried out pollen analysis of cores
C-96, C-127 and C-146. Interpretetaions, analysis, discussion and conclusions have
been done by DI. The design and draft of the manuscript was prepared by DI. All
authors read and approved the final manuscript.
Competing interests
The authors declare that they have no competing interests.
PublishersNote
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Received: 19 March 2018 Accepted: 22 October 2018
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Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 25 of 25
... Several quantitative methods have been developed during the last few decades based This article is a contribution to the special issue "Palaeobotanical contributions in honour of Volker Mosbrugger" on this assumption, e.g. the Climate Leaf Analysis Multivariate Programme (CLAMP) (Wolfe 1993), the Coexistence Approach (CA) (Mosbrugger and Utescher 1997;Utescher et al. 2014), the Leaf Margin Analysis (Wilf 1997), the Climatic Amplitude method (Fauquette et al. 1998), and the European Leaf Physiognomic Approach (ELPA) (Traiser et al. 2005). In this way, a number of local, regional and global climatic reconstructions have been proposed for the Neogene period (Bertini 2010(Bertini , 2002(Bertini , 2006Bruch and Gabrielyan 2002;Ivanov et al. 2002Ivanov et al. , 2007aIvanov et al. , b, c, 2011Bruch and Kovar-Eder 2003;Fauquette and Bertini 2003;Uhl et al. 2003Uhl et al. , 2006Uhl et al. , 2007aBruch et al. , 2004Bruch et al. , 2006Bruch et al. , 2007Bruch et al. , 2011Mosbrugger et al. 2005;Traiser et al. 2005Traiser et al. , 2007Fauquette et al. 2006Fauquette et al. , 2007Jiménez-Moreno 2006;Jiménez-Moreno and Suc 2007;Jiménez-Moreno et al. 2007a, b, c, 2008a, b, 2009Utescher et al. , 2009aUtescher et al. , b, 2011aUtescher et al. , b, 2013Utescher et al. , 2015Alçiçek and Jiménez-Moreno 2013;Ivanov 2015;Ivanov and Worobiec 2017;Yavuz et al. 2017, Popova et al. 2017, Ivanov and Lazarova 2019. ...
... Another important feature of the fossil flora is the low quantity of herbaceous plants. For the Eastern Paratethys, the emergence of open habitats and the distribution of herbaceous vegetation during the late Miocene characterised the flora and the vegetation turnover (Ivanov et al. , 2007aFeurdean and Vasiliev 2019;Ivanov and Lazarova 2019). That is not registered in the present section. ...
... Climate data calculated for the Beli Breg microflora are well within the range of values reconstructed for upper Miocene succession in neighbouring areas, e.g. the Forecarpathian Basin , Staniantsi Basin (Utescher et al. 2009a), Tundzha Basin (Ivanov and Lazarova 2019), and Danube Valley/Belgrade ). The climate record of the Forecarpathian Basin (Drenovets) shows comparative values in the lower part of the Pontian sediments, while in the upper part, the record displays a trend to higher temperature and annual precipitation when compared to our data. ...
Article
Late Miocene sediments from the Beli Breg Coal Basin, Western Bulgaria, were investigated using spore-pollen analysis. Based on palynological characteristics, we describe dynamics and development of vegetation in the studied basin. The main types of palaeocoenoses are distinguished. The fossil flora is characterised by a variable structure of plant communities and diversity of dominant species. In general, the warm temperate representatives of the genera Quercus, Castanea, Corylopsis, Ulmus, and Carya dominated the composition of mixed mesophytic forest palaeocoenoses. Climate data reconstructed using the Coexistence Approach method show that the climate was of a moderately warm type, with a mean annual temperature of ca. 16 °C and temperatures ca. 4 °C by mean in the winter season, thus providing very favourable climatic conditions for the distribution of warm temperate vegetation. The established values for precipitation of about 1000 mm annually indicate the presence not only of a warm but also humid climate, with low seasonality and relatively short dry period.
... In this study, nine selected coal samples (K-3, 4, -5, -6, -9, -11, -15, -16 and -17) were palynologically studied (Fig. 4). Taxonomic identifications of the fossil spores and pollen were based on published atlases and sporomorph keys (Akgün et al. 2007;Biltekin et al. 2015;Bouchal et al. 2017;Bruch and Gabrialyan, 2002;Bruch et al. , 2004Bruch et al. , 2006Güner et al. 2017;Ivanov and Lazarova, 2005;Ivanov and Lazarova, 2019;Ivanov et al. 2002Ivanov et al. , 2007aIvanov et al. , 2007bIvanov et al., 2010;Kayseri and Akgün 2008;Kayseri-Özer et al., 2014b, a;Kayseri-Özer 2014Kayseri-Özer , 2017Mosbrugger and Utescher 1997;Uhl et al. 2003;Utescher et al., 2007aUtescher et al., , b, 2009aUtescher et al., , 2009bUtescher et al., , 2014Yavuz et al., 2017). The studied samples were prepared based on the standard technique (hydrochloric acid (HCl), hydrofluoric acid (HF), potassium hydroxide (KOH), and heavy liquid separation (ZnCl 2 ) and were stored in glycerin) for disintegrating Neogene sediments (Erdtman 1966). ...
... According to the palynological records of the Turkish and European Neogene Basins, the Miocene palynoflora has a unique palynofloral content (e.g. Bertini 2006;Biltekin et al. 2015;Fauquette et al. 2007; Ivanov 2015;Ivanov and Lazarova 2019;Ivanov and Worobiec 2017;Ivanov et al. 2007aIvanov et al. , 2011Jiménez-Moreno and Suc 2007;Karayigit et al. 1999;Kayseri and Akgün 2008;Jiménez-Moreno, 2006;Kayseri-Özer et al., 2014a, b;Popova et al. 2017;Uhl et al. 2007aUhl et al. , 2007bUtescher et al., 2009aUtescher et al., , 2009bUtescher et al., , 2011aUtescher et al., , 2011bUtescher et al., , 2013Utescher et al., , 2015Yavuz et al. 2017). The existence and abundance of some spore species (e.g. ...
... These gymnosperms thrived at middle and high altitude areas and/or were generaly observed in the deciduous forest during the Neogene (e.g. Casas-Gallego et al., 2020;Ivanov and Lazarova 2019;Kayseri and Akgün 2008). Among the other coniferous pollen, Cedrus is predominant (between 5-10%), while Tsuga, Picea, and Abies are less common, usually in the range of 1-3%. ...
Article
The Harmancık Basin, in the north-easternmost Miocene graben in western Anatolia, hosts a 12.6-m-thick coal seam located in the Keles coalfield, in which coals are being exploited by open-cast mining methods. Syngenetic clinoptilolite/heulandite-type zeolite formation in the upper part of coal seam and carbonaceous clayey diatomite as a roof rock have been identified for the first time, and the palaeoenviromental reconstruction of the coal seam was conducted using a multidisciplinary approach. The coal facies and palynological data show that vegetation and depositional changes took place during the middle Miocene, which resulted in vertical variations in elemental and mineralogical compositions. During the initial stages of mire development woody vegetation (e.g. pollen with affinity to Cupressaceae) prevailed, telmatic conditions were common, and preservation of organic matter was high due to anoxic conditions. Thus, relatively low-ash yield was observed in the lower and middle parts of the coal seam. Furthermore, the presence of kaolinite and smectite-type clay mineral aggregates in these parts of the coal seam suggests that alteration of synchronous volcanic inputs took place under weak acidic to neutral conditions. In contrast, limnotelmatic conditions prevailed during the late stages of peat-accumulation, and macrophytes coinciding with herbaceous peat-forming vegetation (e.g. Osmundaceae, Polypodiaceae, and Nymphaeaceae) were dominant. The elevated Gelification Index (GI) values in the uppermost parts of the coal seam could be related to development of alkaline conditions in the palaeomires, which also caused formation of syngenetic clinoptilolite/heulandite-type zeolite from the alkaline activations of synchronous volcanic inputs. Even though palynological data points to the prevalence of freshwater conditions during peat-accumulation, B enrichments along Sr/Ba ratio higher than 1.0 could point to possible marine influence; however, no Neogene marine deposits have been identified in the Harmacik Basin. Nevertheless, the SEM-EDX data show the presence of traceable Ba and Sr in clinoptilolite/heulandite grains, and Sr-bearing barite around feldspar grains in the studied samples from the upper parts of the coal seam. This implies K-feldspars and K-rich alkali-feldspars, derived from synchronous volcanic ash fall, altered under alkaline conditions. Moreover, alginite proportions increased towards the upper parts of the seam, while relatively high Hydrogen Index (HI) values were reached in the uppermost part of coal seam and carbonaceous clayey diatomite roof-rock sample. Furthermore, palynolgical data imply that vegetation changes towards the roof of the coal seam reflect the progressive development of more humid conditions and nutrient-rich surface waters, which favoured increased algal activity.
... These are common constituents of most of the Late Neogene mesophytic plant palaeocommunities on the territory of Bulgaria (e.g. Bozukov et al., 2011;Ivanov, 1997;Ivanov et al., 2008;Ivanov et al., 2002;Ivanov and Ashraf, 2007;Ivanov and Lazarova, 2019;Palamarev, 1964;Palamarev et al., 2002;Palamarev et al., 1999), and therefore, their presence in the studied samples is not surprising. However, since many gymnosperm pollen grains are resistant to degradation and highly adapted to long distance transport (e.g. ...
... Many of these genera are also common in other Late Neogene wetland and mesophytic vegetation communities (e.g. Ivanov et al., 2008;Ivanov et al., 2002;Ivanov and Lazarova, 2019;Palamarev et al., 2002), and represent different ecological habitats -i.e. water logged environments (Sparganiaceae and/or Typhaceae, Potamogeton, and Cyperaceae), and swamp and riparian forests (Alnus, Carya, Pterocarya, Acer, Zelkova, Myrica) within or around the basin. ...
... The plant source, however, cannot be referenced since the presented palynological data provide no evidence. Although a continuous record of the presence of Fagaceae species throughout the Tertiary peat-forming environments on the territory of Bulgaria exists Ivanov and Ashraf, 2007;Ivanov and Lazarova, 2019), none of the previous organic geochemical studies recognized the presence of onocerane I. This fact suggests that Fagaceae species are rather unlike source of onocerane I in the studied lignite. ...
Article
The paper reports the results of the organic petrological, palynological and geochemical characterization of lignite samples from the Kipra lignite seam (Late Miocene, Maritsa-West Basin, Bulgaria). The bulk of the organic matter (OM) is represented by highly gelified detrohuminite with locally abundant leaf-derived ulminite. Liptinite group is characterized by predominance of microsporinite and liptodetrinite, locally with cutinite and fluorinite. Terpene resinite and suberinite are rare. Low TPI and high GI indices indicate peat formation from vegetation with low preservation potential, deposited under water-logged environment of marsh- or fen-type. The palynological results reveal a vegetational community representing different habitats (i.e. mesophytic, marginal and aquatic). The relatively poor preservation of the palynomorphs, however, suggests vegetation that was more diverse during peat formation. Although gymnosperm palynomorphs predominate, the gymnosperm organic matter contribution was probably minor as indicated by the low contents of sesqui- and diterpenoid biomarkers. Because of the absence of triterpenoid biomarkers of neither oleanane, nor lupane or ursane-type, it is considered that angiosperms that do not synthesize their precursors predominated, or the depositional environment had unfavorable characteristics, which prevented the transformation of the triterpenoid precursors. The extractable organic matter yield from the Kipra lignite is low, and dominated by saturated compounds, while polar compounds and asphaltenes occur in low amounts. Aromatic compounds are completely absent. The saturated hydrocarbons are mainly composed of n-alkanes, accompanied by minor amounts of branched- (including isoprenoids) and cycloalkanes, sesqui- and diterpenoids, steroids and hopanoids. Straight chain alkanes are prevailed by long-chain homologues, but show rather mature distribution with CPI ~ 1. Biological (e.g. bacterial) activities and/or environmental control are considered as the main factor/s controlling the observed uncommon n-alkane distributions. A rather uncommon pentacyclic terpenoid, i.e. onocerane I, was tentatively identified in one sample, based on its characteristic fragmentation pattern. Based on its presence, a very specific plant community is considered, and/or specific palaeoenvironmental conditions occurred at least temporarily during the peat formation. However, the responsible plants could not be identified. The low amounts of hopanoid biomarkers, together with the low amounts of n-alkanones, are consistent with limited aerobic biodegradation of the plant remains. The mature 22S/(22S + 22R) C30 hopane ratio (~ 0.55), as well as the random huminite reflectance values (~0.3–0.4%), which are more than twice higher than previously reported, argue for local a increase of coalification degree, presumably due to increased thermal influx around major faults.
... The method was recently applied for palaeoclimate reconstructions in Europe and Asia (e.g. Pross et al. 1998;Utescher et al. 2000;Uhl et al. 2003;Ivanov et al. 2002Ivanov et al. , 2011Biltekin et al. 2015;Durak & Akkiraz 2016;Ivanov & Worobiec 2017;Kayseri-Özer 2017;Kayseri-Özer et al. 2017;Yavuz et al. 2017;Ivanov & Lazarova 2019). For a given fossil flora, the CA method determines the nearest living relatives of fossil taxa and their climatic tolerances and calculates the coexistence intervals (minimum and maximum values) for various climate parameters (for details see Utescher 1997 andUtescher et al. 2014) within which all living relatives of fossil species can coexist. ...
... The following climate parameters were considered as presenting the main climate characteristics: MAT -mean annual temperature (°C), TCM -mean temperature of the coldest month (°C), TWM -mean temperature of the warmest month (°C), MAP -mean annual precipitation (mm). In addition, a brief description of fossil vegetation is also presented based on autecological analysis (Ivanov 2015;Ivanov & Worobiec 2017;Ivanov & Lazarova 2019). ...
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Article
An analysis of selected macrofloras (leaves, fruits and seeds) from NW Bulgaria using the Coexistence аpproach method was applied to obtain quantitative data about Volhynian and Bessarabian climate in studied area. The aim of the study is to compare the climate data derived from the analysis of macrofloras and palynological data. The Middle Miocene was a period of a subtropical/warm temperate humid climate with mean annual temperature between 16 and 18 o C and mean annual precipitation between 1,100 and 1,300 mm. Comparison of all data, received from different floras we can observed, showed that nevertheless some differences, in all cases there was a good relation between climate and vegetation dynamics. We observed some deviations in quantities, but they varied in small limits. The climate data derived from macro-and microfloras coincided well in regard to all parameters, nevertheless that different taxa determined coexistence intervals. In some cases, the macropalaeobotanical data provide narrow climate interval, that is explained by better taxonomic resolution and better identification of nearest living relatives (NLRs). The application of both methods has the advantage of obtaining both more accurate climate data and tracking climate change in more detail throughout the study period.
... The studied samples were prepared using techniques for Cenozoic sediments reported by Erdtman (1966). Taxonomic identifications of the fossil spores and pollen were based on published atlases and palynological studies of Anatolia with morphological properties (e.g., Ivanov et al., 2002Ivanov et al., , 2007aIvanov et al., , 2007bAkgün et al., 2007;Utescher et al., 2007Utescher et al., , 2009Utescher et al., , 2014Kayseri and Akgün, 2008;Kayseri-Özer et al., 2014aKayseri-Özer et al., , 2014bBouchal et al., 2017;Kayseri-Özer, 2013Kayseri-Özer, , 2017Güner et al., 2017;Yavuz et al., 2017;Ivanov and Lazarova, 2019). The vertical distributions of identified fossil pollen and spores were prepared using TGView 2.0.2 and TILIA 2.0.b.4 software (Grimm, 1991(Grimm, , 2004, while cluster analyses of palynological data were conducted using CONISS software (Grimm, 1987). ...
Article
The Şarkikaraağaç coalfield is located in the north-western part of the Lake Beyşehir Basin, which is the most significant graben area in the eastern flank of Isparta Angle, and hosts a 300-Mt coal resource. This study focuses on the first palaeoenvironmental and palaeoclimatic reconstruction of Pliocene and early Pleistocene coal-bearing sequences cored in the two coal exploration wells (SK-1 and SK-2) using coal petrography, mineralogy, faunal (ostracod and mollusk), and floral (palynology and diatom) data from four coal seams (from bottom to top: B, A, X-1, and X-0) with the variable total thickness (1 to 7 m). According to the palynological data, warm and humid climate conditions prevailed during the early Pliocene, and the precursor peats of seams A and B were mainly accumulated under limno-telmatic conditions, with high contributions of herbaceous peat-forming plants. Nevertheless, the co-occurrence of syngenetic carbonate minerals and framboidal pyrites along with calcareous fossil and diatom remains implies neutral to weakly alkaline conditions within palaeomires of these seams. Furthermore, ostracod and gastropod fauna from these seams might imply nutrient-rich shallow water conditions and spring support (e.g., karstic aquifer) into palaeomires. Thus, algal activity within the palaeomires was presumably high, and freshwater algae and diatoms were commonly identified in these seams.With the development of increased uplift ratio of central Taurides and climatic changes towards to late stages of Pliocene and particularly early Pleistocene, the common peat-forming plants within palaeomires and vegetation in the surrounding areas were changed. The increased precipitation caused an elevation of water levels in the study area; hence, the precursor peats of the seam X-1 were accumulated under wet forest mire conditions. This increase also explains the existence of ostracod and mollusk fauna related to river and spring support underlying sequences of the seam X-1. With the ceasing of accumulation of peat of the seam X-1, the climate became drier, and very shallow water conditions have been common. The development of spring support and relatively high precipitation in a short period of time allowed for final peat accumulation (seam X-0) during the early Pleistocene. Nevertheless, this period was followed by the development of relatively colder conditions in the study area, and cold small water conditions were developed during the end of the early Pleistocene. Furthermore, microthermic vegetation was common in the vicinity of the palaeomires during the early Pleistocene. Overall, the peat accumulation and water level of lakes in the study area seem to be controlled by climatic oscillations and uplift of margins of the Lake Beyşehir Basin during the Pliocene to early Pleistocene.
... The basement rocks and the metamorphic rock cover near the site include muscovite, quartz, plagioclase, microcline, alkali feldspar, biotite, epidote, titanite, bluish-green amphibole, chlorite, opaque minerals, garnet, staurolite, zircon, and apatite [18,[21][22][23]. The basement rocks, granitoids, and metamorphic rocks are overlain by Tertiary sediments (Eocene sedimentary rocks and upper Miocene to partially lowermost Pleistocene sediments [16,18,24,25]). The upper Miocene to Pleistocene sediments underlie and extend a few kilometers around the study site. The Eastern Rhodope massif consists mainly of Paleozoic basement rocks (metagranitoids, migmatite, and gneiss), medium-to high-grade metamorphic rocks (amphibolite, eclogite, metabasic rocks, and metaultrabasic rocks), and low-grade metamorphic rocks (greenschist, pelitic schist, phyllite, and marble) [27][28][29][30]. ...
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Article
Several pottery sherds from the Svilengrad-Brantiite site, Bulgaria, were mineralogically and petrographically analyzed. The aim was to add information to the very scarce material data available for Early Bronze Age pottery in the southeastern Thrace plain, Bulgaria, in order to examine a possible raw-material source of the pottery. The characterization techniques applied were optical microscopy (OM), petrographic microscopy (PM), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM-EDS), X-ray fluorescence (XRF) spectroscopy, and X-ray diffraction (XRD). The pottery samples consisted of two typological groups: a local-made type and a cord-impressed decoration type influenced by foreign cultures. All of the samples were produced from fine clay pastes that had a quite similar composition, with abundant mineral grains of similar mineral composition and fragments of metamorphic and granitic rocks. The chemical compositions of each mineral in the grains and fragments were almost identical, and consistent with those from metamorphic and granitic rocks from the Sakar-Strandja Mountains near the study site. The clay paste compositions corresponded to those of illite/smectite mixed-layer clay minerals or mixtures of illite and smectite, and the clay-mineral species were consistent with those in Miocene–Pleistocene or Holocene sediments surrounding the site.
... Taxodium and/or Glyptostrobus species, which are common in Bulgarian Neogene coal-bearing basins (e.g. Ivanov and Lazarova, 2019;Stefanova et al., 2013), seem likely candidates for coal precursors. ...
... Zachos et al., 2001), fossil pollen (e.g. Liu et al., 2011;Chevalier et al., 2014;Ivanov and Lazarova, 2019), and fossil leaves (e. g. Jacobs, B. F., 2002;Liu et al., 2011;Peppe et al., 2018), and different reconstruction methodologies, such as Integrated Plant Record (IPR), Plant Community Scenarios (PCS), and Plant Functional Type (PFT) (Franç ois et al., 2017). ...
Article
Concern about the course of the current environmental problems has raised interest in investigating the different scenarios that have taken place in our planet throughout time. To that end, different methodologies have been employed in order to determine the different variables that compose the environment. In paleoecology, these variables are used for the reconstruction of paleoenvironments. Therefore, the objective of the present study was to reconstruct the environment of the early Miocene of Simojovel, Chiapas, using the taxonomic affinity of flower structures preserved in amber as a proxy. We used the method of the nearest living relative (NLR) for an estimation of the paleovegetation, which resulted in a high evergreen forest with the presence of mangrove elements and flooding zones. The paleoclimatic reconstruction was obtained using the Mutual Ecogeographic Range (MER) method, which resulted in a mean annual temperature of 24.19 ± 1.79 °C and a mean precipitation of 1745 ± 336 mm per year. These results indicate that the environmental conditions of the Miocene of Chiapas exhibited a tropical climate warmer (+1.99 °C) and drier (−337.7 mm) than the Present. Thus, the use of methods alternative to conventional ones used in plant macrofossils, together with a good proxy, such as flowers in amber as in our study, can help to infer the conditions of a fossil locality using quantitative and qualitative parameters.
... The method was recently applied for paleoclimate reconstructions in Europe and Asia (e.g. Pross & al. 1998;Utescher & al. 2000, Ivanov & al. 2002, 2011, Ivanov & Worobiec 2017, Ivanov & Lazarova 2019. For a given fossil flora, the CA method determines the nearest living relatives of fossil taxa and their climatic tolerances and calculates the coexistence intervals (minimum and maximum values) for various climate parameters (for details see Utescher 1997 andal. ...
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Article
The problem of paleoclimate reconstruction is an extremely interesting issue, which has been repeatedly discussed in many publications. This topic engages the attention of numerous specialists in many and various scientific disciplines. Fossil plants have vast potential as a source of information about past climatic conditions in the terrestrial realm. Various methods have been developed for the extraction of climate information from fossil land plants, but only few of these methods have provided quantitative data, e.g. Leaf Margin Analysis, Leaf Area Index, CLAMP and Coexistence Approach (CA). In this study we analyzed Middle Miocene floras from Bulgaria aiming to compare the results from different methods. The fossil floras are located in the southernmost part of the Forecarpathian Basin (NW Bulgaria). Two types of models were used to obtain quantitative data about the paleoclimate characteristics in the studied area-Simple Linear Regression (SLR) and Multiple Linear Regression (MLR) model. Furthermore, CLAMP and CA were applied. The obtained results evidence overlapping of CLAMP and CA data for diverse floras, while CLAMP data tend to produce cooler estimates than those obtained with the CA. The temperatures calculated by the SLR and MLR models are more or less consistent, but only when the standard deviations are considered. Moreover, the SLR and MLR intervals have strong correlation with those obtained from the CA. This corroborates statements by other authors, that under favorable circumstances (high diversity of the fossil flora and good taxonomic resolution) the climatic resolution of the CA can be twice as high compared to Leaf Physiognomy Approaches. The results obtained from the CA have less variability, consistently with data obtained from the MLR model. A great advantage of the CA method is that the width of coexistence intervals does not depend on species richness.
Article
This study presents the stratigraphy, biostratigraphy and palaeoecology of a 420- m thick sequence of the Mamuca Formation (Dümrek Basin, Eskişehir, Turkey). The age for the strata of the Mamuca Formation in the Çakıroğlu Creek section is narrowed to late Ypresian-Lutetian (early-middle Eocene) by benthic foraminifera (Nummulites planulatus, N. burdigalensis, Assilina placentula, A. laxispira and A. cuvillieri), planktonic foraminifera (Acarinina bulbroki, Acarinina rohri and Acarinina topilensis) and ostracoda (Eopaijenborchella longicosta and Bairdia gliberti). The sedimentation started in coastal conditions and changed basinward into a shallow marine environment. The palynological assemblage is documented by frequency of palms Spinizonocolpites, Proxaperties and Longapertites, and unknown botanical affinity of Psilodiporites iszkaszentgyoergyi linking them to mangrove environments, along with pteridophytic spores indicating coastal sedimentation. Subsequently, a relative sea-level rise is obvious, leading to a sharp increase in the abundance of organic-walled dinocysts and a decrease in mangroves, almost died-off. The following faulting caused a tectonically triggered subsidence of the basin and led to an environment that deepened even more, provided that it was still shallow marine conditions that allowed the accumulation of coarse-grained sediments, devoid of fossil. Palynological data, stable isotopes (δ¹⁸O and δ¹³C) and quantitative palaeoclimate estimates point to a warm (probably tropical) and humid climate during the late Ypresian and Lutetian.
Article
Precise estimates of past temperatures are critical for understanding the evolution of organisms and the physical biosphere, and data from continental areas are an indispensable complement to the marine record of stable isotopes. Climate is considered to be a primary selective force on leaf morphology, and two widely used methods exist for estimating past mean annual temperatures from assemblages of fossil leaves. The first approach, Leaf Margin Analysis, is univariate, based on the positive correlation in modern forests between mean annual temperature and the proportion of species in a flora with untoothed leaf margins. The second approach, known as the Climate-Leaf Analysis Multivariate Program, is based on a modern data set that is multivariate. I argue here that the simpler, univariate approach will give paleotemperature estimates at least as precise as the multivariate method because (1) the temperature signal in the multivariate data set is dominated by the leaf-margin character; (2) the additional characters add minimal statistical precision and in practical use do not appear to improve the quality of the estimate; (3) the predictor samples in the univariate data set contain at least twice as many species as those in the multivariate data set; and (4) the presence of numerous sites in the multivariate data set that are both dry and extremely cold depresses temperature estimates for moist and nonfrigid paleofloras by about 2°C, unless the dry and cold sites are excluded from the predictor set. New data from Western Hemisphere forests are used to test the univariate and multivariate methods and to compare observed vs. predicted error distributions for temperature estimates as a function of species richness. Leaf Margin Analysis provides excellent estimates of mean annual temperature for nine floral samples. Estimated temperatures given by 16 floral subsamples are very close both to actual temperatures and to the estimates from the samples. Temperature estimates based on the multivariate data set for four of the subsamples were generally less accurate than the estimates from Leaf Margin Analysis. Leaf-margin data from 45 transect collections demonstrate that sampling of low-diversity floras at extremely local scales can result in biased leaf-margin percentages because species abundance patterns are uneven. For climate analysis, both modern and fossil floras should be sampled over an area sufficient to minimize this bias and to maximize recovered species richness within a given climate.
Article
Reconstructions of past vegetation and climate are crucial for our understanding of regional palaeovegetation. In this study the regional palaeovegetational and palaeoclimatic properties of the late Oligocene and Miocene-Pliocene interval of Anatolia are presented using the Integrated Plant Record (IPR) vegetation analysis and the Coexistence Approach (CA). The IPR analysis allows the reconstruction of six types of zonal vegetation: broad-leaved deciduous forests, mixed mesophytic forests, broad-leaved evergreen forests, subhumid sclerophyllous forests, xeric open woodlands, and xeric grasslands or steppes all identified from the macro-microfloras of Anatolia. In the late Oligocene, warm subtropical and humid climatic conditions prevailed, and the palaeovegetation was represented by mixed mesophytic forests. From the late early-early middle Miocene to late middle Miocene temperature decreased slightly. Broad-leaved evergreen and mixed mesophytic forests and ecotones between these forests were the common zonal vegetation types in Anatolia during this period. According to these palaeoclimatic data based on pollen floras, it can be stated that the middle Miocene cooling affected the terrestrial areas of Anatolia. Besides, precipitation values of the late middle Miocene were slightly higher compared to the late early Miocene. Increasing precipitation rates can be interrelated with increasing humidity. Furthermore, low percentages of the sclerophyllous + legume-type components and a high percentage of the broad-leaved deciduous components support increased humidity in Anatolia during the late middle Miocene. Temperatures increased from the Tortonian to the beginning of the Messinian, and thereafter decreased significantly during the Messinian. Precipitation distinctly increased in Anatolia at the Mio-Pliocene transition. Moreover, palaeoclimatic and zonal vegetational changes in Anatolia during the late Miocene-Pliocene are first identified, and mixed mesophytic forests, ecotone between broad-leaved evergreen and mixed mesophytic forests, subhumid sclerophyllous forests, xeric open woodlands and zonal xeric grasslands or steppes vegetation type are recorded from this time interval. The cooling from the early to late Pliocene is recorded based on the numerical climatic values and the increase in the broad-leaved deciduous components.
Article
Radiometric and palynological data of the Upper Oligocene-Lower Miocene Soma Formation from the Kalkım-Gönen Basin yield new results related to age and palynological contents. In this study, Upper Oligocene strata from the Danişment and Linfa areas and Lower Miocene strata from the Bengiler area were sampled palynologically and for radiometric dating. The Danişment assemblage, which is older than the Linfa assemblages, mainly contains coniferous and evergreen to deciduous mixed mesophytic forest elements. Relatively high quantities of the altitudinal plants Picea and Abies, indicate a cooler palaeoclimate. The Linfa associations mainly include coniferous and riparian elements. Pollen of the riparian plant Alnus and Taxodiaceae indicative for the swamp forest community were predominant, probably as a result of a high lake level. There is a hiatus during the Oligocene-Miocene transition, probably showing a nondepositional phase and sea-level fall indicating the Mi-1 glaciation event. Higher in the sequence, the Aquitanian Bengiler sediments include high amounts of coniferous forest elements as well as components indicative for the evergreen and deciduous mesophytic forest and also riparian forest and swamp forest. Due to presence of thermophilous taxa Reveesia, Mastixiaceae and Arecaceae a warm and humid palaeoclimate is inferred according to quantitative analyses using the Coexistence Approach.
Article
An integrated stratigraphic study of Neogene lacustrine succession in the Çankırı Basin (Central Anatolia), combining pollen analysis, biostratigraphy and isotope analysis records variations in vegetation and depositional environment. The palynological analysis of the upper Miocene interval of the studied section reveals the existence of a coniferous forest. This flora reflects warm-temperate, humid climatic conditions. The pollen changes observed at the onset of the Pliocene are related to climatic changes. In the early Pliocene the vegetation changed to a mixed coniferous forest dominated by meso-microthermic trees (Cedrus and Cathaya) with a widespread herbaceous understory (Poaceae) sparcely interspersed with open areas occupied by Asteraceae whereas Abies and deciduous trees (Quercus, Carya, Juglans, Ulmus, Carpinus, Acer, etc.) are represented by lower percentages. This flora reflects a warm-temperate, relatively arid climate, reflecting the global warm climate of the Early Pliocene. The fluctuations in abundance of Tsuga may represent fluctuations in temperature. Climate analysis using the Coexistence Approach (CA) shows the presence of precipitation oscillations within the Pliocene. The identified ostracod assemblage indicates a dominance of fresh water conditions during the early late Miocene and of brackishwater conditions during the late lateMiocene while minor salinity oscillation is present throughout the section. The δ18Osulfate and 87Sr/86Sr isotopic ratios of non-marine gypsum are indistinguishable from the marine evaporites. This suggests recycling of oldermarine evaporiteswhich is also supported by intense replacement of ostracods by gypsum.
Article
The Miocene represents a time in Eurasia when evergreen and thermophilous dominated Paleogene vegetation was replaced by deciduous and temperate plants. Climatically, it is the transition from a greenhouse to an icehouse world, with the middle Miocene Climatic Optimum as the last warm episode of Earth history. Processes of plant evolution, transformation of vegetation and coenotic structure were significantly forced by both, changes in the global climate system, and also by significant palaeogeographic reorganizations. To give new insight in the middle Miocene evolution of European ecosystems and climate dynamics, we compared plant assemblages from northern Bulgaria and southern Poland (southern Paratethyan and Polish Lowlands realms).
Article
The Elhovo structural depression was formed during the neotectonic phase. It consists of two synforms - Elhovo and Jambol, divided by a slightly outlined structural treshold of about 100o strike. The strike of the Elhovo synform is about 30o and here lignite coal accumulated best. The Jambol synform is smaller, striking about 145o and the coal seams in it are represented only by black shists. Vertical movements prevail since the end of the Romanian and during the Quaternary. -from Abstracts of Bulgarian Scientific Literature