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
and Maria Lazarova
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.
Keywords: Palynology, Palaeobotany, Coexistence approach, Neogene, Tundzha Basin, Bulgaria
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.
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: firstname.lastname@example.org
Institute of Biodiversity and Ecosystem Research, Bulgarian Academy of
Sciences, 23 Acad. G. Bonchev Str., BG-1113 Sofia, Bulgaria
© 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
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,
2011a,2011b,2013,2015; Alçiçek and Jiménez-Moreno
2013;Ivanov2015; Ivanov and Worobiec 2017;Yavuzet
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. 150–200 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 13–14). 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, 6–7 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 5–10 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
Cathaya: pollen of Cathaya sp.;
Mesothermic elements: (Quercus,Carya,Pterocarya,
Carpinus betulus,Carpinus orientalis,Ostrya,Parrotia,
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):
High-altitude trees (microthermic elements): Abies,
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.;
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,
1990–2018) 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).
4.1 Palynological subdivision of the Elhovo formation
Core C-432 (Fig. 3)
Local pollen zone Tu-1
Ulmus -Betula -Carya
Age: late Miocene.
Distribution: 79.0–61.0 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 64.5–61.0 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: 60.0–46.0 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 48.0–46.0
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 River”outcrop
(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
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.
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.
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. ‘Taxodioid’Cupressaceae
cf. Euphorbia Thalictrum sp.
Ericaceae Tilia sp.
Table 1 Taxonomic composition of the fossil pollen flora from
the Tundzha Basin (Continued)
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.
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: 1–9) 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.
3–10 and Pl. 3–11 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: 29–33), 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. 3–14)
and the second closer to Pterocarya serrata Schneider
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. 3–12) and Juglandi-
pollis maculosus (Pot.) Kohlman-Adamska (Pl. 3–13).
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,
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
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.; 2–5–Zelkova sp.; 6, 7 –Eucommia sp.; 8–10 –
Quercus sp. 1; 11, 12 –Quercus sp. 2; 13–15 –Quercus sp. 1 (Polar view); 16, 17 –cf. Parrotia;18–20 –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; 31–33 –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,
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.
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. 1–9–Engelhardia 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; 19–21 –cf. Euphorbia; 22, 23 –Persicaria sp.; 24
–Tricolporopollenites sp.; 25, 26 –Poaceae; 27 –Ericaceae; 28 –Sparganium sp.; 29 –Botryococcus sp.; 30, 31 –Tricolporopollenites
sibiricum;32–Bambusoideae (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
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
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 2006–2009;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 5.0–7.0 °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, 5.0–8.1 °C
and 5.0–9.6 °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-
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 24.7–27.8 °C and 24.7–27.3 °C (with
one exception at 61 m; Fig. 11) and the average summer
temperatures are in the range of 26.0–26.3 °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
to 1308 mm/
, and the average curve is slightly above 1000 mm.
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 64.5–62.5 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 60.0–46.0 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-
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,
riparian forests involving species of the genera Salix,
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-
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
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
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
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
14.4–15.8 °C, the winter temperatures were 3.7–5.8 °C,
the summer temperatures were 25.6–26.4 °C, and the
annual rainfall was in the range of 961–1179 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
13.6–18.4 °C, CMT as 2.4–9.4 °C, WMT as 22.8–26.1 °C,
and MAP as 740–1206 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 (740–1206 mm)
may reflect also the diversity in the climatic conditions
of a larger area, and the presence of habitats with a drier
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.
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.
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
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.
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.
The authors declare that they have no competing interests.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
Received: 19 March 2018 Accepted: 22 October 2018
Akgün, F., M.S. Kayseri, and M.S. Akkiraz. 2007. Palaeoclimatic evolution and
vegetational changes during the late Oligocene-Miocene period in Western
and Central Anatolia (Turkey). Palaeogeography, Palaeoclimatology,
Palaeoecology 253 (1–2): 56–90.
Akkiraz, M.S., M.S. Kayseri, and F. Akgün. 2008. Palaeoecology of coal-bearing
Eocene sediments in Central Anatolia (Turkey) based on quantitative
palynological data. Turkish Journal of Earth Sciences 17: 317–360.
Alçiçek, H., and G. Jiménez-Moreno. 2013. Late Miocene to Pliocene fluvio-
lacustrine system in Karacasu Basin (SW Anatolia, Turkey): Depositional,
palaeogeographic and palaeoclimatic implications. Sedimentary Geology 291:
Angelova, D., N. Popov, and M. Mikov. 1991. Stratigraphy of the quaternary
sediments in the Tundzha depression. Review Bulgarian Geological Society 52:
99–105 (in Bulgarian with English abstract).
Bertini, A. 2002. Palynological evidence of upper Neogene environments in Italy.
Acta Universitatis Carolinae, Geologica 46: 15–25.
Bertini, A. 2006. The northern Apennines palynological record as a contribute for
the reconstruction of the Messinian palaeoenvironments. Sedimentary
Geology 188–189: 235–258.
Biltekin, D., S.-M. Popescu, J.-P. Suc, P. Quézel, G. Jiménez-Moreno, N. Yavuz, and
M.N. Çağatay. 2015. Anatolia: A long-time plant refuge area documented by
pollen records over the last 23million years. Review Palaeobotany Palynology
Bondarenko, O.V., N.I. Blochina, and T. Utescher. 2013. Quantification of Calabrian
climate in southern Primory'e, Far East of Russia —An integrative case study
using multiple proxies. Palaeogeography, Palaeoclimatology, Palaeoecology
Bozukov, V., T. Utescher, and D. Ivanov. 2009. Late Eocene to Early Miocene
climate and vegetation of Bulgaria. Review Palaeobotany Palynology 153:
Bruch, A.A., S. Fauquette, and A. Bertini. 2002. Quantitative climate reconstructions
on Miocene palynofloras of the Velona Basin (Tuscany, Italy). Acta Universitatis
Carolinae, Geologica 46: 27–37.
Bruch, A.A., and I. Gabrielyan. 2002. Quantitative data of the Neogene climatic
development in Armenia and Nakhichevan. Acta Universitatis Carolinae,
Geologica 46: 41–48.
Bruch, A.A., and J. Kovar-Eder. 2003. Climatic evaluation of the flora from
Oberdorf (Styria, Austria, Early Miocene) based on the coexistence approach.
Phytologia Balcanica 9 (2): 175–185.
Bruch, A.A., D. Uhl, and V. Mosbrugger. 2007. Miocene climate in Europe —
Patterns and evolution: A first synthesis of NECLIME. Palaeogeography,
Palaeoclimatology, Palaeoecology 253 (1–2): 1–7.
Bruch, A.A., T. Utescher, and V. Mosbrugger. 2011. Precipitation patterns in the
Miocene of Central Europe and the development of continentality.
Palaeogeography, Palaeoclimatology, Palaeoecology 304: 202–211.
Bruch, A.A., T. Utescher, V. Mosbrugger, I. Gabrielyan, and D.A. Ivanov. 2006. Late
Miocene climate in the circum-alpine realm —A quantitative analysis of
terrestrial palaeofloras. Palaeogeography, Palaeoclimatology, Palaeoecology
Bruch, A.A., T. Utescher, C.A. Olivares, N. Dolakova, D. Ivanov, and V. Mosbrugger.
2004. Middle and Late Miocene spatial temperature patterns and gradients
in Europe —Preliminary results based on palaeobotanical climate
reconstructions. Courier Forschungsinstitut Senckenberg 249: 15–27.
Burchfiel, B.C., R. Nakov, T. Tzankov, and L.H. Royden. 2000. Cenozoic extension in
Bulgaria and northern Greece: The northern part of the Aegean extensional
regime. In Tectonics and magmatism in Turkey and the surrounding area.
Geological Society of London, Special Publication, ed. E. Bozkurt, J.A.
Winchester, and J.D.A. Piper, vol. 173, 325–352.
Dragomanov, L., G. Angelov, E. Kojumdgieva, N. Nikolov, and I. Komogorova.
1984. The Neogene in Haskovo district. Palaeontology, Stratigraphy, Lithology
20: 71–75 (in Bulgarian with English abstract).
Durak, S.D.Ü., and M.S. Akkiraz. 2016. Late Oligocene–Early Miocene palaeoecology
based on pollen data from the Kalkım-Gönen Basin (Northwest Turkey).
Geodinamica Acta 28: 295–310.
Fauquette, S., and A. Bertini. 2003. Quantification of the northern Italy Pliocene
climate from pollen data: Evidence for a very peculiar climate pattern. Boreas
32 (2): 361–369.
Fauquette, S., J. Guiot, and J.-P. Suc. 1998. A method for climatic reconstruction
of the Mediterranean Pliocene using pollen data. Palaeogeography,
Palaeoclimatology, Palaeoecology 144 (1–2): 183–201.
Fauquette, S., J.-P. Suc, A. Bertini, S.-M. Popescu, S. Warny, N. Bachiri Taoufiq, M.-J.
Perez Villa, H. Chikhi, N. Feddi, D. Subally, G. Clauzon, and J. Ferrier. 2006. How
much did climate force the Messinian salinity crisis? Quantified climatic
conditions from pollen records in the Mediterranean region. Palaeogeography,
Palaeoclimatology, Palaeoecology 238 (1–4): 281–301.
Bachiri-Taoufiq, A. Bertini, M. Clet-Pellerin, F. Diniz, G. Farjanel, N. Feddi,
and Z. Zheng. 2007. Latitudinal climatic gradients in the Western
European and Mediterranean regions from the Mid-Miocene (c. 15 Ma) to
the Mid-Pliocene (c. 3.5 Ma) as quantified from pollen data. The
Micropalaeontological Society, Special Publications, The Geological Society,
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 23 of 25
Favre, E., G. Escarguel, J.-P. Suc, G. Vidal, and L. Thévenod. 2008. A contribution to
deciphering the meaning of AP/NAP with respect to vegetation cover.
Review Palaeobotany Palynology 148: 13–35.
Gordon, A., and H.J.B. Birks. 1972. Numerical methods in quaternary palaeoecology. I.
Zonation of pollen diagrams. New Phytologist 71 (5): 961–979.
Gradstein,F.M.,J.G.Ogg,M.D.Schmitz,andG.M.Ogg.2012.The geologic time scale.Vol.
1. Boston, Elsevier; 1144 p., https://doi.org/10.1016/B978-0-444-59425-9.01001-5.
Gradstein, F.M., J.G. Ogg, A.G. Smith, W. Bleeker, and L.J. Lourens. 2004. A new
geologic time scale, with special reference to Precambrian and Neogene.
Episodes 27 (2): 83–100.
Grimm, G.W., J.M. Bouchal, T. Denk, and A. Potts. 2016. Fables and foibles: A
critical analysis of the Palaeoflora database and the coexistence approach for
palaeoclimate reconstruction. Review Palaeobotany Palynology 200: 211–228.
Grimm, G.W., and T. Denk. 2012. Reliability and resolution of the coexistence
approach —A revalidation using modern-day data. Review Palaeobotany
Palynology 172: 33–47.
Hofmann, C.-Ch., and R. Zetter. 2005. Reconstruction of different wetland plant
habitats of the Pannonian Basin system (Neogene, eastern Austria). Palaios
Hristova, V., and D. Ivanov. 2014. Late Miocene vegetation and climate
reconstruction based on pollen data from the Sofia Basin (West Bulgaria).
Palaeoworld 23 (3–4): 357–369.
Ivanov, D. 2004. Pollen of some exotic plants in the Neogene of Bulgaria. Acta
Palaeobotanica 44: 69–77.
Ivanov, D. 2010. Palaeoclimate reconstructions for the Late Miocene in the
Southeast Bulgaria using pollen data from the Tundzha Basin. In Scientific
Annals, School of Geology, Aristotle University of Thessaloniki, Special, ed. G.
Christofides, N. Kantiranis, D.S. Kostopoulus, and A.A. Chatzipetros, vol. 100,
269–278. Thessaloniki, Greece: Proceedings of the XIX CBGA Congress.
Ivanov, D. 2015. Climate and vegetation change during the late Miocene in
Southwest Bulgaria based on pollen data from the Sandanski Basin. Review
Palaeobotany Palynology 221: 128–137.
Ivanov, D., A.R. Ashraf, and V. Mosbrugger. 2007c. Late Oligocene and Miocene
climate and vegetation in the eastern Paratethys area (Northeast Bulgaria),
based on pollen data. Palaeogeography, Palaeoclimatology, Palaeoecology 255
Ivanov, D., A.R. Ashraf, V. Mosbrugger, and E. Palamarev. 2002. Palynological
evidence for Miocene climate change in the Forecarpathian Basin (central
Paratethys, NW Bulgaria). Palaeogeography, Palaeoclimatology, Palaeoecology
178 (1–2): 19–37.
Ivanov, D., A.R. Ashraf, T. Utescher, V. Mosbrugger, and E. Slavomirova. 2007b.
Late Miocene vegetation and climate of the Balkan region: Palynology of the
Beli Breg Coal Basin sediments. Geologica Carpathica 58 (4): 367–381.
Ivanov, D., V. Bozukov, and E. Koleva-Rekalova. 2007a. Late Miocene flora from SE
Bulgaria: Vegetation, landscape and climate reconstruction. Phytologia
Balcanica 13 (3): 281–292.
Ivanov, D., N. Djorgova, and E. Slavomirova. 2010. Palynological subdivision of
Late Miocene sediments from Karlovo Basin, Central Bulgaria. Phytologia
Balcanica 16 (1): 23–42.
Ivanov, D., and M. Lazarova. 2005. Late Miocene flora from Tundzha Basin.
Preliminary palynological data. Comptes rendus de l'Academie bulgare des
Sciences 58 (7): 799–804.
Ivanov, D., T. Utescher, V. Mosbrugger, S. Syabryaj, D. Djordjević-Milutinović,andS.
Molchanoff. 2011. Miocene vegetation and climate dynamics in eastern and
central Paratethys (southeastern Europe). Palaeogeogra phy, Palaeoclimatology,
Palaeoecology 304: 262–275.
Ivanov, D., and E. Worobiec. 2017. Middle Miocene (Badenian) vegetation and
climate dynamics in Bulgaria and Poland based on pollen data.
Palaeogeography, Palaeoclimatology, Palaeoecology 467: 83–94.
Jacques, F.M.B., S.-X. Guo, T. Su, Y.-W. Xing, Y.-J. Huang, Y.-S. Liu, D.K. Ferguson,
and Z.-K. Zhou. 2011. Quantitative reconstruction of the Late Miocene
monsoon climates of Southwest China: A case study of the Lincang flora
from Yunnan Province. Palaeogeography, Palaeoclimatology, Palaeoecology
Jacques, F.M.B., G.L. Shi, H.M. Li, and W.M. Wang. 2014. An early–middle Eocene
Antarctic summer monsoon: Evidence of ‘fossil climates’.Gondwana Research
Jiménez-Moreno, G. 2006. Progressive substitution of a subtropical forest for a
temperate one during the middle Miocene climate cooling in Central Europe
according to palynological data from cores Tengelic-2 and Hidas-53
(Pannonian Basin, Hungary). Review Palaeobotany Palynology 142: 1–14.
Jiménez-Moreno, G., H.A. Aziz, F.J. Rodriguez-Tovar, E. Pardo-Iguzquiza, and J.-P.
Suc. 2007c. Palynological evidence for astronomical forcing in Early Miocene
lacustrine deposits from Rubielos de Mora Basin (NE Spain). Palaeogeography,
Palaeoclimatology, Palaeoecology 252 (3): 601–616.
Jiménez-Moreno, G., A. de Leeuw, O. Mandic, M. Harzhauser, D. Pavelic, W.
Krijgsman, and A. Vranjkovic. 2009. Integrated stratigraphy of the Early
Miocene lacustrine deposits of Pag Island (SW Croatia): Palaeovegetation and
environmental changes in the Dinaride Lake system. Palaeogeography,
Palaeoclimatology, Palaeoecology 280: 193–206.
Jiménez-Moreno, G., S. Fauquette, and J.-P. Suc. 2008a. Vegetation, climate and
palaeoaltitude reconstructions of the eastern Alps during the Miocene based
on pollen records from Austria, Central Europe. Journal of Biogeography 35
Jiménez-Moreno, G., S. Fauquette, J.-P. Suc, and H.A. Aziz. 2007a. Early Miocene
repetitive vegetation and climatic changes in the lacustrine deposits of the
Rubielos de Mora Basin (Teruel, NE Spain). Palaeogeography, Palaeoclimatology,
Palaeoecology 250 (1): 101–113.
Jiménez-Moreno, G., O. Mandic, M. Harzhauser, D. Pavelic, and A. Vranjkovic.
2008b. Vegetation and climate dynamics during the early middle Miocene
from Lake Sinj (Dinaride Lake system, SE Croatia). Review Palaeobotany
Palynology 152 (3–4): 270–278.
Jiménez-Moreno, G., S.-M. Popescu, D. Ivanov, and J.-P. Suc. 2007b. Neogene
flora, vegetation and climate dynamics in southeastern Europe and the
northeastern Mediterranean. In Deep-Time Perspectives on Climate Change:
Marrying the Signal from Computer Models and Biological Proxies, ed. M.
Williams, A.M. Haywood, F.J. Gregory, and D.N. Schmidt, 503–516. London:
The Micropalaeontological society, geological society, Special Publications.
Jiménez-Moreno, G., F.J. Rodriguez-Tovar, E. Pardo-Iguzquiza, S. Fauquette, J.-P.
Suc, and P. Muller. 2005. High-resolution palynological analysis in late early-
middle Miocene core from the Pannonian Basin, Hungary: Climatic changes,
astronomical forcing and eustatic fluctuations in the central Paratethys.
Palaeogeography, Palaeoclimatology, Palaeoecology 216 (1): 73–97.
Jiménez-Moreno, G., and J.-P. Suc. 2007. Middle Miocene latitudinal climatic
gradient in Western Europe: Evidence from pollen records. Palaeogeography,
Palaeoclimatology, Palaeoecology 253: 208–225.
Kayseri-Özer, M.S. 2017. Cenozoic vegetation and climate change in Anatolia —A
study based on the IPR-vegetation analysis. Palaeogeography, Palaeoclimatology,
Palaeoecology 467: 37–68.
Kayseri-Özer, M.S., L. Karadenizli, F. Akgün, N. Oyal, G. Saraç, Ş.Şen, C. Tunoğlu,
and A. Tuncer. 2017. Palaeoclimatic and palaeoenvironmental interpretations
of the late Oligocene, Late Miocene-early Pliocene in the Çankırı-Çorum
Basin. Palaeogeography, Palaeoclimatology, Palaeoecology 467: 16–36.
Kojumdgieva, E., S. Stojkov, and S. Markova. 1984. Lithostratigraphy of the
Neogene sediments in Tundzha Basin. Review of Bulgarian Geological Society
45 (3): 287–295 (in Bulgarian with English abstract).
Mai, D., and E. Palamarev. 1997. Neue paläofloristische Funde aus kontinentalen
und brackichen Tertiärformationen in Bulgarien. Feddes Repertorium 108:
Meulenkamp, J.E., M. Kovac, and I. Cicha. 1996. On late Oligocene to Pliocene
depocentre migrations and the evolution of the Carpathian–Pannonian
system. Tectonophysics 266: 301–317.
Meulenkamp, J.E., and W. Sissingh. 2003. Tertiary palaeogeography and
tectonostratigraphic evolution of the Northern and Southern Peri-Tethys
platforms and the intermediate domains of the African–Eurasian convergent
plate boundary zone. Palaeogeography, Palaeoclimatology, Palaeoecology 196:
Mosbrugger, V., and T. Utescher. 1997. The coexistence approach —A method
for quantitative reconstructions of tertiary terrestrial palaeoclimate data using
plant fossils. Palaeogeography, Palaeoclimatology, Palaeoecology 134 (1–4):
Mosbrugger, V., T. Utescher, and D.L. Dilcher. 2005. Cenozoic continental climatic
evolution of Central Europe. Proceedings of the National Academy of Sciences
102 (42): 14964–14969.
Nakov, R., B.C. Burchfiel, T. Tzankov, and L.H. Royden. 2001. Late Miocene to
recent sedimentary basins of Bulgaria. Geological Society of America Map and
Chart Series, MCHO 88: 1–28.
Nikolov, I. 1985. Catalogue of the localities of tertiary mammals in Bulgaria.
Palaeontology, Stratigraphy and Litholology 21: 43–62.
Nix, H. 1982. Environmental determinants of biogeography and evolution in Terra
Australis. In Evolution of the Flora and fauna of arid Australia, ed. W.R. Barker
and P.J.M. Greenslade, 47–66. Frewville: Peacock Publishing.
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 24 of 25
Palamarev, E. 1989. Paleobotanical evidences of the tertiary history and origin of
the Mediterranean sclerophyll dendroflora. Plant Systematics and Evolution
Palamarev, E. 1990. Grundzüge der paläofloristischen Paläosukzessionen im
Spätmiozän (Sarmatien-Pontien) Bulgariens. In Proceedings of the
symposium Palaeofloristic and Palaeoclimatic changes in the cretaceous and
tertiary, Prague 1989,ed.E.KnoblochandZ.Kvaček, 257–263. Prague:
Palamarev, E., and V. Bozukov. 2004. The macroflora of Neogene sediments in the
Elhovo formation (Southeast Bulgaria). Phytologia Balcanica 10 (2–3): 131–146.
Palamarev, E., and D. Ivanov. 1998. Über einige Besonderheiten der tertiären
Floren in Bulgarien und ihre Bedeutung für die Entwicklungsgeschichte der
Pflanzenwelt in Europa. Acta Palaeobotanica 38: 147–165.
Palamarev, E., and D. Ivanov. 2001. Charakterzüge der Vegetation des Sarmatien
(Mittel-bis Obermiozän) im südlichen Teil des Dazischen Beckens (Südost
Europa). Palaeontographica 259: 209–220.
Palamarev, E., and D. Ivanov. 2004. Badenian vegetation of Bulgaria: Biodiversity,
palaeoecology and palaeoclimate. Courier Forschungsinstitut Senckenberg 249:
Palamarev, E., D. Ivanov, and V. Bozukov. 1999. Paläoflorenkomplexe im
Zentralbalkanischen Raum und ihre Entwicklungsgeschichte von der
Wende Oligozän/Miozän bis ins Villafranchien. Flora Tertiaria Mediterranea
VI (5): 1–95.
Popescu, S.-M. 2006. Late Miocene and early Pliocene environments in the
southwestern Black Sea region from high-resolution palynology of DSDP site
380A (leg 42B). Palaeogeography, Palaeoclimatology, Palaeoecology 238 (1–4):
Popov, S.V., I.G. Shcherba, L.B. Ilyina, L.A. Nevesskaya, N.P. Paramonova, S.O.
Khondkarian, and I. Magyar. 2006. Late Miocene to Pliocene
palaeogeography of the Paratethys and its relation to the Mediterranean.
Palaeogeography, Palaeoclimatology, Palaeoecology 238: 91–106.
Pross, J., S. Klotz, and V. Mosbrugger. 2000. Reconstructing palaeotemperatures
for the early and middle Pleistocene using the mutual climatic range
method based on plant fossils. Quaternary Science Reviews 19: 1785–1799.
Rögl, F. 1998. Palaeogeographic considerations for Mediterranean and paratethys
seaways (Oligocene to Miocene). Annalen des Naturhistorischen Museums in
Wien 99: 279–310.
Rögl, F. 1999. Mediterranean and paratethys. Facts and hypotheses of an
Oligocene to Miocene paleogeography (short overview). Geologica
Carpathica 50: 339–349.
Savov, S. 1983. Construction of the Elhovo structural decline. Review Bulgarian
Geological Society 44 (3): 326–331 (in Bulgarian with English abstract).
Stringmeteo, 2006–2009. Climate data for reference Bulgarian stations (1961–
1990, Monthly weather-fore-cast of NIMH). https://www.stringmeteo.com/
synop/bg_climate.php?m1=7&m2=8&station (in Bulgarian). Last accessed: 28
Suc, J.-P. 1984. Origin and evolution of the Mediterranean vegetation and climate
in Europe. Nature 307: 429–432.
Temniskova-Topalova, D., D.A. Ivanov, and E. Popova. 1996. Diatom analysis on
Neogene sediments from the Elhovo Basin in South Bulgaria. Geologica
Carpathica 47 (5): 289–300.
Temniskova-Topalova, D., and N. Ognjanova-Rumenova. 1997. Description,
comparison and biostratigraphy of the nonmarine Neogene diatom floras
from southern Bulgaria. Geologica Balcanica 27 (1–2): 57–81.
Traiser, C., S. Klotz, D. Uhl, and V. Mosbrugger. 2005. Environmental signals from
leaves —A physiognomic analysis of European vegetation. New Phytologist
Traiser, C., D. Uhl, S. Klotz, and V. Mosbrugger. 2007. Leaf physiognomy and
palaeoenvironmental estimates —An alternative technique based on an
European calibration. Acta Palaeobotanica 47 (1): 181–201.
Uhl, D., A. Bruch, C. Traiser, and S. Klotz. 2006. Palaeoclimate estimates for the
middle Miocene Schrotzburg flora (S Germany): A multi-method approach.
International Journal of Earth Sciences 95 (6): 1071–1085.
Uhl, D., S. Klotz, C. Traiser, C. Thiel, T. Utescher, E. Kowalski, and D.L. Dilcher.
2007b. Cenozoic paleotemperatures and leaf physiognomy —A European
perspective. Palaeogeography, Palaeoclimatology, Palaeoecology 248: 24–31.
Uhl, D., V. Mosbrugger, A. Bruch, and T. Utescher. 2003. Reconstructing
palaeotemperatures using leaf floras —Case studies for a comparison of leaf
margin analysis and the coexistence approach. Review Palaeobotany
Palynology 126: 49–64.
Uhl, D., C. Traiser, U. Griesser, and T. Denk. 2007a. Fossil leaves as palaeoclimate
proxies in the Palaeogene of Spitsbergen (Svalbard). Acta Palaeobotanica 47
Utescher, T., M. Böhme, T. Hickler, Y. Liu, V. Mosbrugger, and F. Portmann. 2013.
Continental climate and vegetation patterns in North America and Western
Eurasia before and after the closure of the central American seaway. In: GSA
125th anniversary annual meeting, Geological Society of America, Abstracts
with Programs, Denver 45, 7, 302.
Utescher, T., M. Böhme, and V. Mosbrugger. 2011a. The Neogene of Eurasia:
Spatial gradients and temporal trends —The second synthesis of NECLIME.
Palaeogeography, Palaeoclimatology, Palaeoecology 304: 196–201.
Utescher, T., O.V. Bondarenko, and V. Mosbrugger. 2015. The Cenozoic cooling —
Continental signals from the Atlantic and Pacific side of Eurasia. Earth and
Planetary Science Letters 415: 121–133.
Utescher, T., A.A. Bruch, B. Erdei, L. François, D. Ivanov, F.M.B. Jacques, A.K. Kern, Y.
Liu, V. Mosbrugger, and R.A. Spicer. 2014. The coexistence approach —
Theoretical background and practical considerations of using plant fossils for
climate quantification. Palaeogeography, Palaeoclimatology, Palaeoecology
Utescher, T., A.A. Bruch, A. Micheels, V. Mosbrugger, and S. Popova. 2011b.
Cenozoic climate gradients in Eurasia —A palaeo-perspective on future
climate change? Palaeogeography, Palaeoclimatology, Palaeoecology 304:
Utescher, T., D. Djordjevic-Milutinovic, A. Bruch, and V. Mosbrugger. 2007.
Palaeoclimate and vegetation change in Serbia during the last 30 Ma.
Palaeogeography, Palaeoclimatology, Palaeoecology 253 (1–2): 141–152.
Utescher, T., D. Ivanov, M. Harzhauser, V. Bozukov, A.R. Ashraf, C. Rolf, M. Urbat,
and V. Mosbrugger. 2009b. Cyclic climate and vegetation change in the late
Miocene of Western Bulgaria. Palaeogeography, Palaeoclimatology,
Palaeoecology 272 (1–2): 99–114.
Utescher, T., and V. Mosbrugger. 1990–2018. The Palaeoflora Database. http://
Utescher, T., V. Mosbrugger, D. Ivanov, and D.L. Dilcher. 2009a. Present-day
climatic equivalents of European Cenozoic climates. Earth and Planetary
Science Letters 284: 544–552.
Velev, S. 1997. Contemporary air temperature and precipitation fluctuations in
Bulgaria. In Geography of Bulgaria, ed. M. Jordanova and D. Donchev, 145–
150. Sofia: Publishing House Bulgarian Academy Sciences (in Bulgarian with
Wilf, P. 1997. When are leaves good thermometers? A new case for leaf margin
analysis. Paleobiology 23: 373–390.
Wolfe, J.A. 1993. A method of obtaining climatic parameters from leaf
assemblages. US Geological Survey Bulletin 2040: 1–71.
Xing, Y.-W., T. Utescher, F.M.B. Jacques, S. Tao, Y.-S. Liu, Y.-J. Huang, and Z.-K. Zhou.
2012. Palaeoclimatic estimation reveals a weak winter monsoon in
southwestern China during the late Miocene: Evidence from plant macrofossils.
Palaeogeography, Palaeoclimatology, Palaeoecology 358–360: 19–26.
Yang, J., Y.-F. Wang, R.A. Spicer, V. Mosbrugger, C.-S. Li, and Q.-G. Sun. 2007.
Climatic reconstruction at the Miocene Shanwang basin, China, using leaf
margin analysis, CLAMP, coexistence approach, and overlapping distribution
analysis. American Journal of Botany 94: 599–608.
Yavuz, N., G. Culha, Ş.S. Demirer, T. Utescher, and A. Aydın. 2017. Pollen, ostracod
and stable isotope records of palaeoenvironment and climate: Upper
Miocene and Pliocene of the Çankırıbasin (Central Anatolia, Turkey).
Palaeogeography, Palaeoclimatology, Palaeoecology 467: 149–165.
Zachos, J., M. Pagani, L. Sloan, E. Thomas, and K. Billups. 2001. Trends, rhythms, and
aberrations in global climate 65 Ma to present. Science 292 (5517): 686–693.
Zdravkov, A., I. Kostova, and J. Kortenski. 2007. Properties and depositional
environment of the Neogene Elhovo lignite, Bulgaria. International Journal of
Coal Geology 71 (4): 488–504.
Ivanov and Lazarova Journal of Palaeogeography (2019) 8:3 Page 25 of 25