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Research Paper
Hydrological isolation of the Paratethys in the late Middle-Late Miocene:
Integrated stratigraphy, palaeoenvironments and biotic record of the
Caspian Basin, Karagiye, Kazakhstan
Sergei Lazarev
a,b,*
, Oleg Mandic
c
, Marius Stoica
d
, Pavel Gol’din
e
, Stjepan ´
Cori´
c
f
,
Mathias Harzhauser
c
, Wout Krijgsman
g
, Dias Kadirbek
h
, Davit Vasilyan
a,b
a
Department of Geosciences, University of Fribourg, Fribourg, Switzerland
b
JURASSICA Museum, Porrentruy, Switzerland
c
Geological-Paleontological Department, Natural History Museum Vienna, Vienna, Austria
d
Faculty of Geology and Geophysics, University of Bucharest, Bucharest, Romania
e
Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, Kyiv, Ukraine
f
GeoSphere Austria, Vienna, Austria
g
Department of Earth Sciences, Utrecht University, Utrecht, the Netherlands
h
School of Mining and Geosciences, Nazarbayev University, Astana, Kazakhstan
ARTICLE INFO
Keywords:
Caspian basin
Eastern Paratethys
Serravallian-Tortonian
Magnetostratigraphy
Biostratigraphy
Vertebrate fauna
ABSTRACT
The hydrological connectivity of semi-isolated basins with the global ocean drives remarkable ecosystem turn-
over and regional climate shifts, making palaeoenvironmental and palaeohydrological studies of the epiconti-
nental basins of high relevance. During the late Middle–Late Miocene, the Paratethys Sea, which occupied vast
areas of the West Eurasian Interior, underwent a notable hydrological isolation from the global ocean. Between
12.65 and 7.65 Ma, the Paratethys experienced signicant water level uctuations and eventually near-total
ecosystem collapse. The causes and timing of these hydrological and biotic changes remain unclear, especially
in the understudied Caspian Sea region. Our study presents an integrated stratigraphic framework of the 136-m-
thick Karagiye section on the east coast of the Caspian Sea (Mangystau region, Kazakhstan). The fauna-rich
deposits document the pre- (Konkian), syn- (Volhynian, Bessarabian and Khersonian) and post-isolation
(Maeotian) phases of Paratethys evolution at its eastern margin. We reconstruct the palaeoenvironmental his-
tory of the Caspian Basin by combining palaeomagnetic dating with biostratigraphic analyses of microfauna,
molluscs, marine vertebrates and calcareous nannoplankton. Our key ndings in the studied section include: 1.
Konkian (incomplete): Open lagoonal environments with restricted connectivity to the global ocean in the early
Konkian followed by a middle Konkian faunal inux and establishment of normal marine environments; 2.
Volhynian (incomplete, 12.3–12.05 Ma): Onset of Paratethys hydrological isolation with marginal lagoonal
environments, new endemic species, plus rare surviving Konkian taxa; 3. Bessarabian (12.05–9.9 Ma): Trans-
gression and offshore setting at ~12.05 Ma with maximum ooding at 11.6 Ma and Intra-Bessarabian Carbonate
Surge at ~10.7 Ma, followed by upper Bessarabian (10.7–9.9 Ma) carbonate platform interior settings; 4.
Khersonian (9.9–7.65 Ma): Khersonian Ecological Crisis, carbonate platform to backshore environments with
hiatus between 9.5 and ~8.0 Ma representing an extreme lowstand. 5. Maeotian (incomplete 7.65–7.0 Ma):
Transgression at 7.65 Ma, followed by a delayed invasion of Maeotian faunas at 7.5 Ma, linked to the recon-
nection of the Caspian Basin with the rest of the Eastern Paratethys. The well-dated biotic record of Karagiye
enhances understanding of Paratethyan hydrological and ecological events in the Caspian Basin and provides a
foundation for further palaeoclimatic and palaeobiogeographic studies across Eurasia.
1. Introduction
The hydrological evolution of enclosed basins (i.e. surrounded by
land), with irregular connectivity history to the global ocean (Healy and
Kenichi, 1991), is a complex and fascinating process. In these systems,
the interplay of tectonics and climate controls the water budget
* Corresponding author. Department of Geosciences, University of Fribourg, Fribourg, Switzerland.sergei.lazarev@unifr.ch
Contents lists available at ScienceDirect
Marine and Petroleum Geology
journal homepage: www.elsevier.com/locate/marpetgeo
https://doi.org/10.1016/j.marpetgeo.2025.107288
Received 18 September 2024; Received in revised form 3 January 2025; Accepted 4 January 2025
Marine and Petroleum Geology 173 (2025) 107288
Available online 11 January 2025
0264-8172/© 2025 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC license ( http://creativecommons.org/licenses/by-
nc/4.0/ ).
(evaporation vs precipitation) and denes the basin connectivity mode
with the global ocean (Meijer, 2012; Simon et al., 2019). Any change in
the gateway conguration may signicantly impact the basinal water
level and, with this, change regional palaeoclimate (precipitation and
temperature) (Zhao et al., 2022; Voigt et al., 2017; Frisch et al., 2019;
Hoyle et al., 2020). Further, water level uctuations (Paramonova,
1994; Popov et al., 2010), erosional processes on land (Schobben et al.,
2016) and connectivity changes with the global ocean (or other basins)
(Flecker et al., 2015; Andreetto et al., 2021) strongly control basinal
water chemistry and aquatic ecosystems. Detailed palaeoenvironmental
and palaeohydrological reconstructions of epicontinental basins are
vital for understanding palaeoprecipitation dynamics and faunal
dispersal pathways.
An outstanding example of an epicontinental basin with a dynamic
connectivity history is the Paratethys – a former Cenozoic Sea in the
West Eurasian interior that, at its maximum extension, spread from
modern Kazakhstan to France (Laskarev, 1924). Since its birth in the
early Oligocene from the Tethys Sea/Ocean, the Paratethys, consisted of
numerous basins that were periodically connected with the global ocean
via tectonically-controlled gateways (R¨
ogl, 1999; Schulz et al., 2005).
During the late Middle – early Late Miocene (Serravallian-Torto-
nian), the Paratethys underwent a major phase of hydrological isolation
(Fig. 1). At 12.65 Ma, the restriction and closure of the Slovenian Strait
disconnected Paratethys from the global ocean. Between 12.65 and 7.65
Ma, during the Volhynian, Bessarabian and Khersonian (sub)stages, the
restricted marine basin transformed into a large anomalohaline lake
(R¨
ogl, 1999; Popov et al., 2022). Later, at 11.7 Ma, the uplift of the
Carpathian mountains separated the Eastern Paratethys from the Central
Paratethys, with the latter transforming into the Lake Pannon (ter Borgh
et al., 2014). The marine cut-off made the Eastern Paratethys water
budget (evaporation vs precipitation) highly sensitive to climatic
changes, resulting in extreme water level uctuations (Popov et al.,
2010). During the Bessarabian, the Eastern Paratethys underwent a
gigantic water surface expansion, ooding the vast territories of Central
Asia and the northern Black Sea margin (Iljina et al., 1976). During the
Khersonian, the Eastern Paratethys experienced water level drops of
~300 m amplitude that repetitively disconnected the Caspian, Euxinian
and Dacian subbasins, exposing large areas of the former shelf (Popov
et al., 2010).
The aquatic Paratethyan ecosystems faced remarkable diversica-
tion and expansion to near-total extinction. Right after the isolation,
during the Volhynian, the aquatic faunal communities gradually radi-
ated and thrived in the Bessarabian. However, at the transition to the
Khersonian lowstand, the ecosystem collapsed: the biodiversity of
molluscs shrunk by about 90%, the entire foraminifera fauna vanished
and the marine vertebrate fauna such as shes, dolphins, whales and
seals went nearly entirely extinct (Paramonova, 1994; Maissuradze and
Koiava, 2011; Popov et al., 2022; Gol’din and Startsev, 2017).
The diversity dynamics of Eastern Paratethys biota are well under-
stood, but the drivers behind the extreme water level uctuations and
biodiversity rise and demise remain elusive. This is mainly related to the
lack of continuous geological outcrops with reliable age constraints. In
Fig. 1. Serravallian-Tortonian regional stages of the Central (CP) and Eastern Paratethys (EP) (A), palaeogeographic evolution of the region (B–E) (redrawn from
(Paramonova, 1994; Popov et al., 2010), (F–G) geographic location (red dot) of the studied outcrop Karagiye (maps are taken from Google Earth©). Abbreviations (in
column) Kar. – Karaganian, Mt. – Maeotian; (on the maps): SS – Slovenian Strait, CS – Carasu Strait, IG – Iron Gate Strait, NUS – North-Ustyurt Shelf, SMS – South
Mangyshlak Shelf, PKS – Pre-Kopet Dag Shelf, SCd – South Caspian Depression, KFB – Kura Foreland Basin, TCD – Terek-Caspian Depression, RB – Rioni Basin, ScS –
Scythian Shelf, DB – Dacian Basin, TB – Transylvanian Basin, PB – Pannonian Basin, VB – Vienna Basin, FCB – Fore-Carpathian Basin.
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
2
line with the Oligocene-Early Miocene Maikopian Series, the Volhynian-
Bessarabian-Khersonian Stages remain one of two poorly dated intervals
in the Paratethys history. Moreover, most of the palaeoenvironmental
recontructions are based on biotic records from the Dacian (Carpathian
Foreland) and the Euxinian (Black Sea) basins (Popov et al., 2016). Its
large easternmost segment – the Caspian Sea misses robust constraints.
In this paper, we present an integrated stratigraphy of the 136-m-
thick Karagiye section in Kazakhstan (Fig. 1), which comprises one of
the most complete Middle–Late Miocene sedimentary successions of the
Caspian Basin. A combination of high-resolution magnetostratigraphy,
sedimentary facies observations, molluscs, microfauna (foraminifera
and ostracods) and calcareous nannoplankton reveals the palae-
oenvironmental evolution of the Eastern Paratethys before, during and
after the Serravalian–Tortonian hydrological isolation. Moreover, we
provide a continuous and well-dated record of marine vertebrate fauna
(whales, dolphins, seals, shes) for the rst time, allowing us to better
understand their responses to palaeoenvironmental perturbations. The
paper aims to create a well-dated biotic and palaeoenvironmental record
for the Volhynian – Khersonian of the Caspian Basin, further contrib-
uting to a broad range of interregional palaeoenvironmental studies
concerning the hydrological evolution of the Paratethys, palae-
obiogeography of aquatic groups and palaeoclimatic reconstructions of
Eurasian Interior.
2. Geological setting and stratigraphy
2.1. Serravallian-Tortonian stratigraphy of the Eastern Paratethys
The Paratethys’s semi-isolated nature throughout its history made it
an important hotspot of diverse endemic faunas, whose correlation to
the Geological Time Scale has been problematic (Harzhauser et al.,
2024b; Popov et al., 2022). Because of that, the Paratethys has its own
regional stratigraphic subdivision, which is mainly based on the
endemic mollusc fauna (Nevesskaya et al., 2003).
The Serravallian-Tortonian stratigraphy of the Eastern Paratethys
comprises the following regional stages: Karaganian, Konkian, Sarma-
tian s.l. and Maeotian (Popov et al., 2022; Raf et al., 2020), with the
rst one being not present in our study and thus not discussed below (but
see Harzhauser et al., 2024a). The term “Sarmatian” was introduced in
1866 for the Central Paratethys (CP) (Suess, 1866) and was later
adopted for the Eastern Paratethys (EP). However, later it was shown
that the Sarmatian in the CP comprises a much shorter stratigraphic
interval (e.g. 12.65–11.6 Ma) than in the EP (e.g. 12.65–7.6 Ma). In
order to resolve the conict on the term use, the stratigraphic committee
adopted a temporal solution by calling the Sarmatian in the CP as Sar-
matian sensu stricto and in the EP – Sarmatian sensu lato (Papp et al.,
1974a). Nowadays, some of the authors use the Sarmatian s.l. substages
– the Volhynian (lower), Bessarabian (middle) and Khersonian (upper),
as independent stages (Palcu et al., 2019; Lazarev et al., 2020). In our
work, we follow this nomenclature and show that these substages have
distinct biostratigraphic signatures that allow us to show and recognise
these units as independent regional stages.
The Konkian Stage dated between 13.4 and 12.65 Ma (Palcu et al.,
2017) is subdivided into three substages: the lower (Kartvelian) marked
by the dominance of the molluscs Barnea and Ervillia; the middle (Sar-
taganian) characterised by a massive inux of euhaline faunas domi-
nated by Limacina, Aequipecten and Loripes molluscs and upper
(Veselyankian) with Timoclea konkensis and Ervilia podolica (Popov et al.,
2022).
The Volhynian Stage characterises the onset of the hydrological
isolation of the Eastern Paratethys. The base of Volhynian is marked by
the Badenian-Sarmatian Extinction Event (BSEE) (Harzhauser and Pil-
ler, 2007; Palcu et al., 2015) and by the rst occurrence of the molluscs
Polititapes vitalianus and Sarmatimactra eichwaldi (Muratov and Neves-
skaya, 1986; Paramonova, 1994). The base of the Volhynian (known as
the base of the Sarmatian s.l.) is concurrent with the base of the
Sarmatian s.s. in the Central Paratethys and has an age of 12.65 Ma
(Palcu et al., 2017).
The Bessarabian Stage begins as a large-scale transgression fol-
lowed by the occurrence of new mollusc fauna with Sarmatimactra
vitaliana, Plicatiformes plicatottoni and Obsoletiformes spp.
(Paramonova, 1994; Popov et al., 2022; Muratov and Nevesskaya,
1986). The base of the Bessarabian lacks any conclusive age constraints
and was previously estimated between 12.2 Ma (Chumakov et al., 1992)
and 11.9 Ma (Harzhauser and Piller, 2004). The lower part of the Bes-
sarabian correlates with the upper Sarmatian s.s. in the Central Para-
tethys, while the upper part (e.g., from 11.6 Ma) corresponds there to
the Pannonian Stage.
The Khersonian Stage signies a massive decline of biodiversity and
the occurrence of new endemic mollusc genera Chersonimactra with only
a few species such as Ch. caspia, Ch. balcica and Ch. bulgarica
(Kojumdgieva et al., 1989; Paramonova, 1994). They become extinct
prior to the Khersonian–Maeotian boundary and the uppermost part of
the Khersonian is therefore referred to as the “Barren biozone”
(Kojumdgieva et al., 1989; Paramonova, 1994). The Bessarabian –
Khersonian boundary is placed between 8.9 and 8.6 Ma in GPTS 2020;
Raf et al., (2020) but has recently been dated in the Panagea outcrop of
the Euxinian Basin at 9.6 Ma with a potential window between 9.8 and
9.6 Ma (Palcu et al., 2021).
The Maeotian Stage begins with a transgression event that termi-
nated the Khersonian lowstand and probably reconnected the Eastern
Paratethys with the global ocean (Vasiliev et al., 2021; Popov et al.,
2022). The faunal record is usually characterised by the occurrence of
fresh-to brackish water mollusc taxa such as Andrusoviconcha panticapea,
Sinzowinaia subhoernesi and Viviparus moldavicus followed by marine
taxa with Dosinia maeotica, Polititapes abichi and Mactra superstes
(Lazarev et al., 2020; Popov et al., 2016). The Khersonian – Maeotian
boundary has been dated with magnetostratigraphy in the Dacian and
Euxinian Basins at 7.65 Ma (Lazarev et al., 2020; Palcu et al. 2019,
2021).
2.2. On the way to isolation: Paratethys and Caspian Basin during the
Serravallian-Tortonian
During most of the Serravallian, the Paratethys Sea combined two
large realms: the Central Paratethys, consisting of the Pannonian,
Vienna, Transylvanian, Dacian and Forcarpathian basins (up to Volhy-
nian), and the bigger Eastern Paratethys, with the Caspian, Euxinian
(Black Sea) and Dacian and Forcarpathian basins (both, starting from
Volhynian) (Fig. 1). During that time, the westernmost Central Para-
tethys was directly connected with the global ocean via the Slovenian
Strait. The Eastern Paratethys did not have a direct connection to the
global ocean and only connected with the Central Paratethys by a Car-
asu/Barlad Strait (until 12.65 Ma) and by an Iron Gate Strait (until 11.7
Ma) (Fig. 1) (Palcu et al., 2017; Popov, 2004). The Caspian Basin, as the
easternmost part of the Eastern Paratethys, consisted of several sub-
basins with three major depocentres –the South Caspian Depression in
the south, the Kura Foreland Basin in the southwest and the
Terek-Caspian Depression in the north-west. The northern and eastern
parts were shallow water shelves – The North Pre-Caspian, Ustyurt and
Mangyshlak and Pre-Kopetdag (Fig. 1). The Caspian Basin was con-
nected with the Euxinian Basin in the north-west via the Scythian Shelf –
Terek-Caspian Depression and in the south-west via the Transcaucasian
Strait (Kura Foreland Basin – Rioni Basin) (Fig. 1) (Popov, 2004).
Before the main endorheic phase, the Paratethys had already expe-
rienced repetitive episodes of restriction and widening of hydrological
connectivity with the global ocean (R¨
ogl, 1999; Popov et al., 2022;
Vernyhorova et al., 2023). The early Serravallian was marked by
Slovenian Strait restriction (Simon et al., 2019; Palcu et al., 2017).
Accompanied by a negative water budget, restricted marine inow
caused thick evaporite formation in the Fore-, Transcarpathian and
Transylvanian basins – a period known as the Badenian Salinity Crisis
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
3
(13.8–13.4 Ma) (De Leeuw et al., 2010; Simon et al., 2019; Peryt, 2006).
At the same time, the restriction of the Carasu Strait resulted in the
Eastern Paratethys freshening and endemic fauna radiation (e.g. Kar-
aganian Stage, 13.8–13.4 Ma) (Palcu et al., 2017). At 13.4 Ma, restored
connectivity through the Slovenian and Barlad Straits re-established
near-marine environments in the entire Paratethys – an interval
known as upper Badenian in the CP and Konkian in the EP (13.4–12.65
Ma) (Palcu et al., 2017; Popov et al., 2022).
During the Konkian, the Eastern-Central Paratethys connectivity was
unstable. After a short reconnection event at the base of the early Kon-
kian (Kartvelian), an isolation phase occurred marked by Barnea-
dominated mollusc fauna (Popov et al., 2022). The sudden inux of
middle Konkian (Sartaganian) euhaline fauna indicates the restoration
of connectivity with marine Central Paratethys (Vernyhorova, 2015).
However, during the upper Konkian (Veselyankian), the new rise of
endemics along with the euhaline taxa potentially points to a gradual
decline of connectivity with the global ocean (Popov et al., 2022).
The eventual termination of the Slovenian Strait at 12.65 Ma (Palcu
et al., 2015) completely isolated the unied Paratethys from the global
ocean, marking the onset of a main endorheic phase. The basin’s salinity
decreased, which provoked the massive extinction of stenohaline faunas
at 12.65 Ma, known as the Badenian-Sarmatian Extinction Event
(Harzhauser and Piller, 2007; Harzhauser et al., 2024b).
The hydrological isolation made the Paratethyan water budget
(evaporation vs. precipitation) highly sensitive to climatic oscillations
(Palcu et al., 2021). During the Volhynian/early Sarmatian s.s., the
Paratethyan water level was generally at a similar level as during the
pre-isolation Konkian/late Badenian (Popov et al., 2010). In contrast, at
the onset of Bessarabian/late Sarmatian s.s., a large-scale transgression
extended far landwards into the northern Black Sea region and Central
Asia (Iljina et al., 1976) (Fig. 1).
In the beginning of Tortonian, the uplit of the Carpathians isolated
the CP from the rest of the Paratethys and transformed it into the Lake
Pannon (ter Borgh et al., 2014). In the terminal Bessarabian, uplift of the
Caucasus and the closure of the Transcaucasian Strait took place
(Cavazza et al., 2024; Mosar et al., 2010; Nemˇ
cok et al., 2013; Sokhadze
et al., 2018). During the Khersonian, a series of sudden high-amplitude
water level drops in the Eastern Paratethys not only disconnected its
subbasins (including the Caspian Basin) but also provoked a near-total
extinction of all faunal groups (Paramonova, 1994; Popov et al., 2010;
Gol’din and Startsev, 2017; Maissuradze and Koiava, 2011). The Eastern
Paratethys endorheic phase was terminated by the Maeotian trans-
gression that shortly reconnected the basin with the global ocean, pre-
sumably via the Aegean Basin (Lazarev et al., 2020; Palcu et al., 2019;
Vasiliev et al., 2021).
3. Methodology
3.1. Logging
The 136-m-thick Karagiye section, located in the south-eastern part
of the Karagiye Depression, comprises three transects (A, B and C),
whose correlation in between was checked by laterally tracing marker
beds (Fig. 2N and O). A series of trenches were dug along each transect,
enabling sampling for palaeomagnetic and biostratigraphic analysis and
lithofacies observations.
The Karagiye section was measured with a Jacob’s staff and a
geological compass. Bedding orientation is mostly horizontal, locally
deepening <5◦. Logging was performed with a resolution of 10–20 cm,
focusing on sediment colour, granulometry, sedimentary structures and
type of bed contact. The outcrop was photographed with a Mavic Air 2
drone, and a 3D model was constructed using Agisoft© software (Fig. 2N
and O).
3.2. Biostratigraphy
3.2.1. Molluscs
For the analysis of mollusc fauna and for the biostratigraphic sub-
division of the outcrop, 132 hand samples were taken. Silicone casts
were made in some beds, where the mollusc fauna was fragile or present
as imprints. The samples were usually 0.5–1 kg in weight and were
either washed and picked over 1 mm sieve or, in case of high fragility,
were gently cleaned, surfaced-glued and studied under the microscope.
Mollusc fauna was identied at the Vienna Natural History Museum,
Austria using Kojumdgieva (1969); Iljina et al., (1976); Nevesskaja et al.,
(1993); Paramonova (1994); Iljina (1993); Harzhauser (2021); Harz-
hauser et al., (2023); Sladkovskaya (2017).
3.2.2. Microfauna
In total, 126 micropalaeontological samples, weight of 300–1000
taken with an average resolution of 1 m, were analysed for ostracods and
foraminifera. Sample processing was performed at the Faculty of Geol-
ogy and Geophysics, University of Bucharest, Romania. The samples
were rst completely dried for the elimination of interstitial water. Next,
samples were boiled for 30–60 min in a sodium carbonate solution for
better disintegration, washed through a battery of sieves (63–500
μ
m)
and dried. Samples were picked under a ZEISS–GSZ microscope. A ZEISS
– Stemi SV11 microscope with a NIKON digital camera was used to
illustrate the key foraminifera and ostracod species.
For identication and palaeoecological evaluations of ostracod, we
used M´
ehes (1908)and Zal´
anyi (1913)for the Central Paratethys species
and Schneider (1953; Schneider, 1939, 1949), Suzin (1956), Pobedina
et al. (1956) for the northern Black Sea, Caucasus and Caspian areas.
Then, the works of Cernajsek (1974); Jiˇ
riˇ
cek (Jiˇ
riˇ
cek, 1974, 1983);
Stancheva (Stancheva, 1963, 1972, 1990); Olteanu (Olteanu, 1989,
1998, 1999, 2006); Zelenka (1990); and the newer contributions of
Fordin´
al et al. (2006); Gross (2006); T´
oth (2008); T´
oth et al. (2010);
Gebhardt et al. (2009); Stoica in ter Borgh et al., 2013 and ter Borgh
et al., 2014 were used; We also referred to studies of Filipescu et al.,
(2014); Dumitriu et al., (2017); Harzhauser et al., (2018); Szur-
omi-Korecz et al., (2021).
Foraminifera identication and biostratigraphic signicance from
the Central Paratethys was based on the historical monograph of d’Or-
bigny (1846), revised by Papp and Schmid (1985), as well as the works
of Korecz-Laky (1968), Brestensk´
a (1974), Papp et al. (1974b), Papp
et al. (1978), G¨
or¨
og (1992) and ter Borgh et al. (2013).
From the Transylvanian and Dacian basins (including the Moldavian
platform) we used the contributions of Filipescu (1996), (2005), (2014),
Silye (2015), Popescu (1995), Popescu and Grihan (Popescu and Grihan,
2002, 2004, 2005, 2008), Brˆ
anzil˘
a (1999), Ionesi (2006), ter Borgh et al.
(2014) and Dimitriu (2017).
From the Transcarpathian and modern Ukraine areas of the Eastern
Paratethys, we used the studies of Bogdanovich (1952), Venglinsky
(1953, 1958, 1962, 1975), Serova (1955), Subbotina et al. (1960),
Didkowski (1961), Didkowski and Satanovskaja (1970) and Pishanova
(1969). For other areas of Eastern Paratethys related to the Caucasus,
Black and Caspian seas Voloshinova (1952), 1958; Krasheninnikov
(1959); Zhizhtschenko (1959); Maisuradze (1971), 1980; Maissuradze
and Koiava (2011); Vernyhorova et al., (2023) were used. For the Polish
part of the Paratethys, we used the papes of Łuczkowska (1974) and
Szczechura (1982). For the interpretation of the foraminifera palae-
oecology, we mainly used Murray (2009).
3.2.3. Calcareous nannofossils
For the investigation of calcareous nannofossils, 103 samples were
prepared using the standard protocol of Perch-Nielsen (1985). Nanno-
fossil assemblages were studied quantitatively and qualitatively (pre-
sence/absence). For biostratigraphic interpretation, standard
nannoplankton zonation dened by Martini (1970) was used. From all
samples containing calcareous nannofossils, at least 300 specimens were
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
4
Fig. 2. Lithological log, stratigraphic units and representative photographs of some lithologies along the section. Explanations for photos from A to M can be found in
Chapter 4.1, subchapters on lithology. N, O: 3D models of the studied outcrop with indicated stratigraphic units and logging paths, N. for transects A and B, O. for
transects B and C. Abbreviations: Mk – Maikopian, Vh – Volhynian, Bs – Bessarabian, Kh – Khersonian, Mt – Maeotian.
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
5
counted to reconstruct palaeoecologic environments. For samples con-
taining poor nannoplankton assemblages, i.e. less than 1 specimen in 10
elds of view under the microscope, only presence/absence analyses
were applied.
3.3. Marine vertebrate fauna
Marine vertebrate fauna remains were collected both in situ and ex
situ (surface ndings/debris), registering their exact stratigraphic levels
or, in the case of an ex situ nd, the relative stratigraphic position. The
fragile fragments were glued in place and, together with other remnants,
packed for further preparation and taxonomic interpretation. Partial
skeletons and isolated bones were identied using Brandt (1873)
Mchelidze (1964, 1984) and Kaz´
ar (2006) and compared with type
specimens when available in museum collections.
3.4. Magnetostratigraphy
To determine magnetic polarity patterns, 344 standard cylindrical
doublet samples were taken throughout the section with a resolution of
0.1–0.5 m. Samples were extracted using a portable battery-powered
drill machine with a 25-mm diamond crone and a pressurised water
tank. Samples were then oriented using a measuring table and a com-
pass, and two parameters (sample tilt and sample azimuth) were
documented.
Palaeomagnetic measurements were done at the Palaeomagnetic
laboratory “Fort Hoofddijk”, Utrecht, the Netherlands. Thermal
demagnetisation (th) was performed on a horizontal 2G Enterprises DC
SQUID magnetometer (noise level 3 ×10
−12
Am
2
) in a shielded room
with an effective internal eld of 0–0.1 mT. Each sample was measured
in multiple positions with temperature increments of 20–40 ◦C either up
to a maximum of 690 ◦C or to the remanent magnetisation dropping
below 10% from the initial natural remanent magnetisation (NRM). For
the determination of magnetic carriers, 10 samples were measured for
thermomagnetic properties in air on a horizontal type Curie balance
(noise level 5 ×10
−9
Am
2
) (Mullender et al., 1993). In addition, for 30
samples, different coercivity fractions of IRM were thermally demag-
netised along three orthogonal axes following the method of Lowrie
(1990). For that, samples were rst magnetised in a horizontal 2G En-
terprises DC SQUID magnetometer along axes x, z and y in 700, 150 and
50 mT elds, respectively and then step-wise thermally demagnetised
up to 700 ◦C in a shielded room with zero eld.
Palaeomagnetic data associated with this manuscript, such as the
interpretation of magnetic components (Supplementary 1) and statisti-
cal tests (Mean directions, 95%-cutoff, reversal test, E/I shallowing test,
Supplementary 2) were done using an online platform Paleomagnetism.
org (Koymans et al., 2016). In our manuscript, we refer to the
Geomagnetic Polarity Time Scale (GPTS) 2020 (Raf et al., 2020).
4. Results
4.1. Stratigraphic intervals and associated fauna
4.1.1. Stratigraphic interval 1 (Pre-Konkian, 0–8.7 m)
4.1.1.1. Lithology. Description: The studied outcrop begins with Strati-
graphic interval (SI) 1, represented by grey to dark greenish grey thinly
(2–4 mm) parallel-laminated claystones (Fig. 2A). On the surface, the
claystones have a paper shale appearance with brownish-red secondary
oxidation, secondary gypsum or yellowish powder of jarosite. In the
studied section, the claystones have a thickness <9 m but become
thicker and better exposed westwards towards the Karagiye Depression
centre. No fossil fauna has been detected in SI1.
Interpretation: The thinly parallel-laminated claystones were accu-
mulated from hemipelagic suspension fall-out in a low-energy
depositional setting (van der Merwe et al., 2010; Jorissen et al., 2018).
The paper shale appearance and abundant jarosite powder on the sur-
face point to the oxidation of iron sulde minerals and may suggest
accumulation in anoxic settings (van et al., 2016a). We interpret the
depositional settings of SI1 as offshore. Similar, clay-dominated low--
energy offshore depositional environments are common around the
globe and are usually described as shelf or offshore facies associations
(Yoshida, 2000; Lazarev et al., 2020).
4.1.2. Stratigraphic interval 2 (Konkian, 8.7–13.9 m)
4.1.2.1. Lithology. Description: SI2 begins with a sharp erosional contact
bounded by secondary gypsum crystals and rare intraformational peb-
bles followed by a set of one to two 10-cm-thick beds of matrix-
supported conglomerates (Fig. 2B). These conglomerates are usually
separated by siltstones and laterally, they either disappear or transform
into thicker, up to 1-m-thick beds with highly irregular bases (Fig. 2B).
Above the conglomerates, the package is represented by greenish grey to
pale yellowish brown (almost white) marlstones with interchangeable
sedimentary structures: 1. speckled, with tiny abundant rusty brown to
black spots (Fig. 2C); 2. thinly (3–4 mm) parallel-laminated, lenticularly
bedded with thin sandy lenses and troughs (Fig. 2D). Except for the
conglomerates, the marlstone beds have gradual basal surfaces.
Interpretation: The matrix-supported sharp-based intraformational
breccia at the base of the Konkian represents transgressive lag deposits.
The laterally extensive incisive conglomerate beds may represent pe-
riods of rapid shoreface progradation related to water level oscillation
within shallow water marginal environments (Nichols, 2009). The
following marsltones with alternating speckled, thinly-laminated and
lenticular structures were formed in shallow water lagoonal environ-
ments. Here, the alternation of speckled and laminated structures may
suggest different levels of the bottom oxygenation and thus facilitate
more and less bioturbation, respectively (Damholt and Surlyk, 2004).
The lenticular bedding with thin sandy stripes and ripple marks was
formed by wave winnowing or tidal processes with bidirectional or
oscillatory currents sorting the sediments at the lagoon bottom (Reineck
and Wunderlich, 1968). Similar lagoonal depositional environments
were previously described in the Upper Cretaceous marginal marine
strata of the Straight Cliffs Formation, USA (Allen and Johnson, 2011).
4.1.2.2. Mollusc fauna. SI2 consists of two mollusc units – 2a and 2b.
Unit 2a is represented by several monospecic shell-concentrations of
disarticulated pholadid bivalve Barnea pseudoustjurtensis (Samples KDM
8.8─KDM 12.0 m, Figs. 3 and 4). They mostly form pavements of hori-
zontally oriented, up to 17-mm-long valves, counting occasionally the
juveniles. The uppermost pholadid pavement is recorded at 12.0 m. Unit
2b (KDM 13─KDM 13.6 m, Fig. 3) begins in yellowish-grey bioturbated
marlstones containing Limacina konkensis, Varicorbula gibba and Appo-
rhais alata. Varicorbula gibba is common and dominantly present by ar-
ticulated shells. Shiny, translucent microscopic shells of the pteropod
gastropod L. konkensis are, in general, badly preserved due to compac-
tion and leaching and occur as single individuals or accumulated thin
lenses.
4.1.2.3. Foraminifera. Rich Konkian benthic foraminifera assemblages
were recorded at levels 12.6 and 13.7 m (Figs. 5 and 6A). No planktonic
foraminifera have been detected. Agglutinated foraminifera are repre-
sented by the species Pseudogaudryna karreriana. Miliolids are richer and
represented by several species, e.g. Pseudotriloculina ex. gr. consobrina,
Quinqueloculina haueriana, Qu. gracilis, Qu. pseudoangustissima, Qu. col-
laris, Qu. tortonica, Adelosina longirostra, Pyrgoella controversa and Sig-
moilina mediterranensis. Strongly and heavily ornamented tests of
Cycloforina serovae, Adelosinia poligonia and Adelosina schreibersi are
common.
Lagenids are moderately recorded, being observed by a few
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6
Fig. 3. Stratigraphic distribution of fossil mollusc fauna in the Karagiye Section and dened biozones plotted against the polarity patterns. The age of magnetic zones
is discussed in Chapter 5.
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specimens of Grigelis pyrula, Dentalina antenula and Laevidentalina com-
munis. Buliminids are represented by frequent specimens of Bulimina
elongata, B. subulata, Globobulimina pyrula, and Fursenkoina acuta
together with the frequent bolivinid Bolivina aff. dilatata. The small-
sized uvigerinids Angulogerina esuriens and Angulogerina angulosa are
frequently observed in our samples. Rotaliid foraminifera are moder-
ately present in the Konkian of Karagiye. We identied specimens of the
species Cibicides konkensis, Melonis soldanii, Porosononion martkobi,
Anomalinoides transcarpathicus and Elphidium aculeatum.
4.1.2.4. Ostracods. In contrast with foraminifera, the Konkian (Unit 2,
8.7–13.9 m) contains a less diverse ostracod association (Figs. 5 and 6B).
We identied four forms, the most frequent being small-sized Cytherois
gracilis. At 10 m, Cythereis caucasica appears in very large numbers.
Olimfalunia plicatula and Sclerochilus sp. are very rare.
4.1.2.5. Nannofossils. Ten samples from SI2 were investigated for
calcareous nannofossils (Fig. 7). Five samples from the lower part
(9.8–11.1 m) contain rare, poorly to moderately preserved nannofossils
with Coccolithus pelagicus, C. miopelagicus, Cyclicargolithus oridanus,
Reticulofenestra pseudoumbilicus and Sphenolithus moriformis (Figs. 7 and
8). The upper part (ve samples from 12.8 to 13.8 m) is rich in well-
preserved nannofossils with regular occurrences of Braarudosphaera
bigelowii, Coccolithus pelagicus, Holodiscolithus macroporus, Rhabdos-
phaera sicca, Reticulofenestra pseudoumbilicus and Syracosphaera medi-
terranea. In addition, there are also Acanthoica cohenii, Calciosolenia
fossilis, Cyclicargolithus oridanus, helicoliths (Helicosphaera carteri, H.
wallichi), Nivisolithus kovacici, N. vrabacii, Pontosphaera multipora,
Umbilicosphaera rotula etc. The upper interval (12.8–13.8 m) of SI2 is
also characterised by a stepwise increase of Coccolithus pelagicus from
the bottom (min. value 0.7% in sample 12.8 m) to the top (max. value
96.8% in sample 13.8 m). The percentages of R. pseudoumbilicus in this
interval follow an opposite trend, with a maximum presence at the
bottom (30.5% in sample 12.8 m) and absence in the uppermost sample
(13.8 m). Similar to R. pseudoumbilicus, the percentages of holococcolith
H. macroporus decrease from sample 12.8 m (13.2%) to the top of SI2
(0.6% in sample 13.8 m). Moreover, very rare reworked specimens from
the Cretaceous and Paleogene were observed.
4.1.3. Stratigraphic interval 3 (Volhynian, 13.9–25.1 m)
4.1.3.1. Lithology. Description: Generally, SI3 has a remarkably white
appearance in the outcrop (Fig. 2O). SI3 starts at 13.9 m with an
irregularly-based 10-cm-thick orange-brown horizon mainly built of
reworked bivalve shells and rare intraclasts. In the interval 14–18 m
(Fig. 2E), SI2 is represented by an alternation of light brown, light
yellowish brown (in dry condition, almost white) marlstones with thin
(2–4 mm) parallel-lamination, speckled structure with mm-scale hori-
zontally elongated black and brown spots, and lenticular bedding with
occasional sandy troughs and wave ripple marks. Among the marlstones,
there are also single 5-cm-thick sharp-based orange-brown coquina
beds. Between 18 and 25.1 m, the coquina beds become more frequent
and up to 30 cm thick (Fig. 2, log). Between 18.4 and 19.6 m, there are
three 10–20 cm thick levels with remarkable perforated structures with
abundant 1–2 mm holes. At 21.3 m is a remarkable sharp-based coquina
bed with highly reworked shells, intraclasts, and abundant cm-scale
rootlets. The marlstone beds in SI3 usually have gradual bases, while
the coquina beds have sharp, slightly irregular basal surfaces.
Interpretation: The depositional environments of SI3 are similar to
those of SI2. Here, the marlstones were accumulated in the low-energy
lagoonal settings. The speckled marlstones and horizons with tiny un-
lled burrows represent serpulid bioturbation (BI =3–4). The lenticular
bedding may either represent a wave winnowing process or stand for the
microtidal activity (Reineck and Wunderlich, 1968). At the same time,
the abundance of shell debris and the presence of rootlet horizons point
to much shallower, lagoonal margin environments that periodically
experienced episodes of subaerial exposure.
4.1.3.2. Mollusc fauna. SI3 (Volhynian) is divided into two parts
delimited by an erosive boundary at 21.3 m, followed by the introduc-
tion of three new gastropod species (Fig. 3). According to the faunal
changes, ve units (3a─3e) are distinguished.
Unit 3a (KDM 14–KDM 15.2 m, Fig. 3). At 13.9 m, the reworked bed
comprises shell fragments and articulated bivalve shells of small-sized
Obsoletiformes ruthenicus and Musculus naviculoides as well as largely
disarticulated shells of Varicorbula gibba (sample KDM 14.0 m, Fig. 3).
Microscopic planktonic gastropod Limacina konkensis and minute
hydrobiid steinkerns are likely present. Above, at 14.1 m, a light
yellowish grey marlstone exhibits a pavement on its top surface with
densely packed, size-sorted and horizontally oriented articulated
bivalve shells of Abra alba and random small-sized cardiid shells (sample
KDM 14.2 m, Sup.1). The lying above light yellowish-brown marlstone
contains scattered shells of A. alba and of some minute cardiids (samples
KDM 14.7─KDM 15.2 m, Fig. 3).
Unit 3b (Samples KDM 15.7─KDM 18.2 m, Fig. 3). At 15.7 m,
orange-brown coarse shell-debris concentration contains small dis-
articulated whole shells, mainly of Ervilia dissita, accompanied by
O. ruthenicus and Mohrensternia sp. (KDM 15.7 m, Fig. 3). Above, the
greenish-brown mudstone includes scattered disarticulated shells of
Sarmatimactra eichwaldi, A. alba, E. dissita and Obsoletiformes sp. (KDM
15.7 m, Fig. 3), grading into a mollusc-barren interval (16.5─18.1 m).
The latter is intercalated at its very top by several thickening upwards,
mm-to few-cm-thick shell concentrations of horizontally oriented dis-
articulated Obsoletiformes obsoletus, A. alba, E. dissita, S. eichwaldi and
Polititapes vitalianus (KDM 18.1─KDM 18.2 m, Fig. 3).
Unit 3c (KDM 18.7–KDM 21.2 m, Fig. 3). The following beige-
coloured interval begins with a 20-cm thick limestone bed with
frequent up to 4-cm-long and 1-mm-broad tubes of bristle worms
(polychaetes) adjoined by a few single and articulated shells of A. alba
and Obsoletiformes sp. and minute hydrobiid gastropods (KDM 18.7 m).
Above, the pale yellowish-grey marlstone comprises in its lower part
common, predominantly horizontally oriented and disarticulated shells
of latter species (KDM 19.4 m); its middle part is barren of molluscs,
whereas in its top part, several thin, densely packed concentrations of
horizontally oriented shells of Obsoletiformes sp. and Musculus navicu-
loides appear (KDM 20.1 m). The three following samples (KDM
19.4─KDM 21.2 m) represent occasional thin horizontal shell concen-
trations of disarticulated Obsoletiformes sp., M. naviculoides, A. alba, E.
dissita and S. eichwaldi.
Unit 3d (KDM 21.4–KDM 22.8 m). The erosional contact at 21.3 m
is overlain by an orange-brown rudstone with shell debris bearing
Fig. 4. Molluscs from Karagiye with indication of the stratigraphic positions (in meters) in the section. Konkian forms: 1. Barnea pseudoustjurtensis, 9.3 m; 2.
Varicorbula gibba, 13.0 m; 3. Apporhais alata, 13.0 m; 4. Limacina konkensis, 14.0 m. Volhynian forms: 5. Musculus naviculoides, 14.0 m; 6. Abra alba, 14.2 m; 7.
Obsoletiformes lithopodolicus, 18.7 m; 8. Acteocina lajonkaireana, 21.4 m; 9. Dorsanum duplicata, 21.4 m; 10. Sarmatimactra crassa, 21.4 m; 11. Plicatiformes praeplicata,
21.4 m; 12. Timisia plicata, 21.4 m, 13. Abra scythica, 22.0 m; 14. Abra reexa, 23.8 m. Lower Bessarabian forms: 15. Plicatiformes plicatottoni, 26.0 m; 16. Ervilia
dissita, 43.5 m; 17. Obsoletiformes obsoletus, 44.0 m; 18. Polititapes tricuspis, 44.0 m; 19. Polititapes vitalianus, 44.0 m; 20. Sarmatimactra vitaliana, 61.5 m. Upper
Bessarabian forms: 21. Barbotella hoernesi, 66.4–79.3 m; 22. Solen submarginatus, 71.15 m; 23. Paradonax lucidus, 74.8 m; 24. Sarmatimactra podolica, 76.3 m; 25.
Plicatiformes ttoni, 85.95 m. Lower Khersonian forms: 26. Chersonimactra cf. caspia, 94.9 m; 27. Chersonimactra bulgarica, 101.25 m; 28. Chersonimactra balcica,
103.2 m; 29. Chersonimactra bulgarica, 105 m. Upper Khersonian forms: 30. Chersonimactra caspia, 114.9 m. Lower Maeotian forms: 31. Lampanella maeotica, 129.5 m;
32. Potamides taitboutii, 129.5 m; 33. Mytilaster minor, 129.5 m; 34. Ervilia minuta, 135.8 m; 35. Loripes pseudoniveus, 135.8 m.
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Fig. 5. Stratigraphic distribution of foraminifera and ostracod faunas and other micropalaeontological groups of the Karagiye section plotted against the age model.
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Fig. 6a. Konkian foraminifera from the Karagiye section. 1-4. Pseudogaudryna karreriana; 5, 6. Quinqueloculina haueriana; 7, 8. Quinqueloculina gracilis; 9,10.
Cycloforina serovae; 11, 12. Adelosinia poligonia; 13, 14. Adelosina schreibersi; 15, 16. Quinqueloculina tortonica; 17, 18. Pyrgoella controversa; 19, 20. Pseudotriloculina
ex. gr. consobrina; 21, 22. Quinqueloculina pseudoangustissima; 23–26. Adelosina longirostra; 27, 28. Sigmoilina mediterranensis; 29, 30. Grigelis pyrula; 31, 32. Dentalina
antenula; 33, 34. Laevidentalina communis; 35, 36. Fursenkoina acuta; 37, 38. Bulimina elongata; 39, 40. Bulimina subulata; 41,42. Angulogerina esuriens; 43, 44.
Angulogerina angulosa; 45, 46. Bolivina aff. dilatata; 47–49. Cibicides konkensis; 50–52. Melonis soldanii; 53,54. Porosononion martkobi; 55–57. Anomalinoides trans-
carpaticus; 58.59. Elphidium aculeatum.
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Fig. 6b. Konkian (1–12) and Volhynian–Khersonian (13–28) ostracods from the Karagiye section. 1-5. Cythereis caucasica; 1,3. Left valve (LV), external view; 2, 4.
Right valve (RV), external view; 5. C, ventral view; 6. Olimfalunia plicatula. LV, fragmented valve; 7,8. Sclerochilus sp.; 7. LV, external view; 8. RV, external view;
9–12. Cythereis gracilis; 9, 11. LV, external view; 10, 12. RV, external view. 13–18. Aurila merita; 13, 15. LV, external view; 14, 16. RV, external view; 17. C, dorsal
view; 18. C, ventral view; 19–24. Aurila mehesi; 19, 21. RV, external view; 20, 22. RV, external view; 23. C, dorsal view; 24. C, ventral view; 25, 26. Aurila sp; 25. LV,
external view; 26. RV, external view; 27, 28. Aurila angularis; 27. LV, external view; 28. RV, external view.
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common Dorsanum duplicatum, Timisia picta, Plicatiformes praeplicatus
and S. eichwaldi, adjoined by rare E. dissita, Polititapes vitalianus, as well
as a few fretted shells of Varicorbula gibba (KDM 21.4 m). A yellowish-
grey marlstone follows above, showing thin shell concentrations of
horizontally oriented A. alba, M. naviculoides and Obsoletiformes sp.
(KDM 21.8 m), overlain by a 15-cm-thick densely packed shell-bed
similar in composition to penultimate one with the exception of pre-
sent A. alba and absent D. duplicatum, P. praeplicatum, P. vitalianus and
V. gibba (KDM 22.0 m). The overlaying two samples represent occasional
shell debris lenses (KDM 22.2 m) and thin shell-bed intercalations (KDM
22.8 m) in marlstones with horizontally oriented shells dominated by
A. alba.
Unit 3e (KDM 23.1–KDM 25.05 m). At 23 m, the orange-brown
shell-debris with clay intercalations bear whole large-sized shells of
O. obsoletus and O. lithopodolicus (KDM 23.1 m), grading upwards into
marlstone with lenses of shell-debris additionally comprising E. dissita
(KDM 23.5 m). The pale yellowish-grey marlstone above includes spo-
radic horizontally-oriented shells of A. abra, A. reexa, M. naviculoides,
O. lithopodolicus, S. eichwaldi and P. vitalianus (KDM 23.8─KDM 24.4 m).
In its upper part, the marsltone bears a densely packed concentration of
bristle worm tubes. The marlstone interval is nally overlain by a
greenish claystone (KDM 25.05 m) bearing small-sized bivalve shells of
O. obsoletus, P. vitalianus, M. naviculoides horizontally oriented and
commonly taking articulated buttery position. The gastropod shells of
D. duplicatum are additionally present.
4.1.3.3. Foraminifera. The part between 13.9 and 19 m is dominated by
Pseudotriloculina ex. gr. consobrina, Porosononion martkobi, Bulimina
elongata, Quinqueloculina pseudoangustissima, Quinqueloculina gracilis,
Quinqueloculina collaris, which survived from the Konkian (Figs. 5 and
9A-B). They are associated with newly occurring species Sinuloculina
angustioris, Varidentella latelacunata, Nonion bogdanowiczi, Elphidium
crispum, Elphidium hauerinum, Elphidium antoninum and Elphidium ch-
tellianum. The sample from 18.2 m shows abundant presence of the
euryhaline species Ammonia ex. gr. beccarii.
A diversication of foraminifera starts at 19 m, with the presence of
rotaliid species such as Porosononion ex. gr. granosum, P. ex. gr. sub-
granosum as well as diverse species of Fissurina genus, like F. cubanica, F.
bicaudata, F. bessarabica, F. carpathica, F. elongata, F. daraensis and the
polymorphinid Guttulina austriaca (Fig. 5). The Volhynian index species
Varidentella reussi appears in small numbers at 19 m and between 19 and
21 m becomes abundant marking the Varidentella reussi Zone (Popescu,
1995).
Samples from 21 to 25.1 m mark the presence of Elphidium species
that show different degrees of development of the marginal spines,
starting with relatively small ones in Elphidium aculeatum, going to forms
with more developed, long spines, as Elphidium josephinum up to Elphi-
dium reginum var. caucasica (Fig. 9B). Many transitional forms are
observed, making taxonomic classication difcult. In the same inter-
val, the Articulina genus appears with the species Articulina problema.
The large number of Elphidium species with marginally developed spines
and associated with miliolid foraminifera of the genus Articulina, denes
the so-called Elphidum reginum Zone (Popescu, 1995).
4.1.3.4. Ostracods. The Volhynian stage marks a progressive diversi-
cation of the ostracod assemblage, especially towards the top of this
interval (Figs. 5, 6B and 9C-D). Only the small-sized Cytherois gracilis
passed the boundary to Volhynian.
The basal part of SI3 (13.9–19 m) is characterised by the dominance
of leptocytherids, among them the most abundant being Amnicythere
tenuis, associated with Euxinocythere aff. marginata. The Loxoconcha
genus is represented by Loxoconcha subcrassula.
Like the foraminifera, starting from 19 m, a greater diversication of
the ostracod fauna is observed. New are the index species Aurila merita
and Aurila mehesi. The loxoconchids are well represented by
L. subcrassula, L. aff. subcrassula, Loxocorniculum schmidi and the rare
thin-shelled Phlyctocythere fragilis. Besides A. tenuis and E. marginata, the
leptocyderids are also represented by Euxinocythere ex. gr. praebosqueti,
Callistocythere naca and two more species – Euxinocythere sp. 1 and
Euxinocythere sp. 2. Three xestolebrids species are identied at this
stratigraphic interval – Xestoleberis aff. dispar, Xestoleberis fuscata and
Xestoleberis glabrescens. The top part of SI3 displays the maximum
diversication and abundance of the Volhynian ostracods.
4.1.3.5. Nannofossils. In total, 35 samples from SI3 were investigated
on calcareous nannofossils. The lowermost part (samples at 14 m, 14.2
m and 14.6 m) is rich in lower salinity indicator species Braarudosphaera
bigelowii. Nannoplankton assemblages from 14.1 to 18.2 m are generally
scarce, moderately preserved and are mostly dominated by species
reworked from the Upper Cretaceous (Arkhangelskiella cymbiformis,
Micula staurophora, Prediscosphaera cretacea, Watznaueria barnesiae etc.)
and Paleogene (Coccolithus formosus, Reticulofenestra bisecta, Retic-
ulofenestra dictyoda, Isthmolithus recurvus, Zygrhablithus bijugatus etc.).
Autochthonous assemblages are comparable with those from SI2
Fig. 7. Distribution of the age-indicative/stratigraphically important calcareous nannoplankton taxa from the Karagiye section.
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(Konkian) containing: Acanthoica cohenii, Coccolithus pelagicus, Retic-
ulofenestra pseudoumbilicus, Nivisolithus kovacici, N. vrabacii, Syr-
acosphaera mediterranea etc. Samples from 19.4 m to 21.45 m are rich in
well-preserved diatoms accompanied by very rare nannofossils. Samples
above the diatoms layer (21.8–24.8 m) are generally barren in nanno-
fossils, containing just a few specimens reworked from the Cretaceous
and Paleogene.
4.1.4. Stratigraphic interval 4 (lower Bessarabian, 25.2–65 m)
4.1.4.1. Lithology. Description: SI4 begins with a remarkable orange-
brown double shell bed separated by a thin claystone intercalation.
Further up, it continues with an alternation of speckled yellowish-grey
claystones and dark greenish grey thinly (1–2 mm) parallel-laminated
0.4–0.6 m thick claystone beds. Starting from 30 m, the claystones
have thin, silty, to very ne-grained sandy laminae (Fig. 2F). From 34 m,
among claystones appear occasional beds of pale yellowish-grey massive
marlstones, locally with speckled structure and concave-down oriented
bivalve shells. From 44 m until the top of SI4, the marlstones prevail and
occasional 20-30 cm-thick orange-brown coquina beds appear with
sharp undulating bases and locally, with swaley cross-stratication. All
the beds except for sharp-based coquinas have gradual basal surfaces.
Interpretation: The basal coquina bed containing both, reworked Vol-
hynian and new Bessarabian taxa was formed as a transgressive lag. The
thin parallel lamination in the claystone suggests accumulation from
suspension fallout in low-energy offshore settings (Jorissen et al., 2018;
van der Merwe et al., 2010). The laterally-delimited sharp-based shell
debris are tempestites deposited within the storm-wave base or offshore
transition zone (Raaf et al., 1977; Dott and Bourgeois, 1982; Nichols,
2009). Later appearance and thickening of marlstones intervals point to
progradation of a carbonate platform (Tucker, 1985; Reading, 1996).
Similar examples of low-energy offshore settings and storm-dominated
offshore transition zones were previously described in Cretaceous de-
posits of the Wasatch Plateau (USA) (Gani, M. R. et al., 2015) and as
offshore-lower shoreface deposits in Cretaceous Upper Almond Forma-
tion (USA) (Kieft et al., 2011).
4.1.4.2. Mollusc fauna. Based on changes in mollusc distribution, we
divided SI4 into 7 units (4a─4f, Fig. 3).
Unit 4a (KDM 25.2–KDM 28.4 m) begins with a 20-cm-thick orange-
coloured, densely packed mollusc-debris concentration delineated by
thin clay intercalation. Samples taken below and above the claystone
(KDM 25.15─24.25 m) include a small number of detectable shells,
including only E. dissita in the lower, accompanied in the upper sample
by Obsoletiformes sp., Musculus naviculoides and Plicatiformes plicato-
ttoni. The claystones include articulated shells of P. plicatottoni, (KDM
25.5─28.4 m). E. dissita and M. naviculoides are present throughout the
entire interval, with the rst being especially common in KDM 26.5 m,
where Polititapes vitalianus starts regularly occurring and Sarmatiamactra
vitaliana is detected. Except for a few thin Ervilia layers, shell concen-
trations are absent in this unit.
Unit 4b (KDM 29.5–KDM 31.5 m), located in dark greenish-grey
claystones, exhibits badly preserved shells of P. vitalianus. In its upper
part, monospecic pavements of E. dissita with concave up-oriented
single valves are present.
In Unit 4c (KDM 32.6–KDM 34.9 m), the greenish grey claystones
passing upwards into yellowish grey marlstones are marked by
concomitant occurrence of P. plicatottoni and P. vitalianus (KDM
32.6─KDM 34.9 m). The former, represented by single and articulated
valves in buttery position and oating in sediments or concentrated in
lenses, is very common in the upper part of the interval. Between KDM
30.7 m and KDM 33.3 m, lenses with numerous Acteocina lajonkaireana
specimens occur, comprising additionally E. dissita. Musculus navicu-
loides occurs in the topmost sample.
Unit 4d (KDM 35.6–KDM 40.1 m, Fig. 3) continues with similar li-
thology, but the mollusc content is reduced solely to P. vitalianus (KDM
35.6─40.1 m). In the lowermost part of the interval, its shells are
concentrated in lenses; above, they are present randomly oating in the
muddy sediment.
Unit 4e (KDM 40.6–KDM 43.5 m, Fig. 3), represented by similar
claystones as in the previous unit, bears thin shell concentrations with
partly articulated P. plicatottoni and P. vitalianus (KDM 41.5─KDM 43.5
m). The topmost sample comprises a 10-cm-thick beige limestone
intercalation with steinkerns of the latter two taxa adjoined by a few
D. duplicatum shells.
Unit 4f (KDM 44–KDM 45.8 m, Fig. 3). At 44.5 m, a composite, clay-
intercalated, orange-coloured 20-cm-thick shell-debris bed bears nicely
preserved shells of Obsoletiformes obsoletus, E. dissita and P. vitalianus
(KDM 44m, Fig. 3). Lower and thicker bed shows large-sized concave-
down bivalve shells at the base (Sample KDM 44.0 m). The reworked bed
is overlain by greyish brown mudstone that starts with a thin concen-
tration of single valves of P. vitalianus followed by a horizon with cluster-
accumulated P. plicatottoni shells (KDM 44.3 m). The greenish-grey
claystone (45.3–45.95 m) begins with rare P. vitalianus followed up-
wards by several up to 10-cm-thick coquinas with small-sized
P. plicatottoni. In the coquinas E. dissita is common, followed by
P. vitalianus, P. plicatottoni, M. naviculoides and D. duplicatum (KDM
45.5─45.8 m).
Unit 4g (KDM 46.4–KDM 49.1 m, Fig. 3) within the pale yellowish-
grey marlstones contains monotypic shell pavements and lenses of
P. vitaliana.
Unit 4h (KDM 51.3–KDM 61.5 m, Fig. 3). The topmost mollusc
bearing interval starts with a 30-cm-thick orange-coloured shell-debris
concentration bearing horizontally oriented shells of O. obsoletus and
P. vitalianus, intercalated by mollusc bearing marl. The shell-debris bed
is overlain by about 10-m-thick alternation of dark and light grayish to
brownish coloured mudrocks with occasional up to 10 cm thick co-
quinas. In its upper sandier part, three up to 4-cm-thick shell-debris
layers occur. Below, several pavements with disarticulated P. vitalianus
shells are present, marked by a regular occurrence of P. vitalianus usually
accompanied by Obsoletiformes sp. E. dissita. The interval ends with a 15-
cm-thick orange shell-debris layer bearing whole single valves of
P. vitalianus and S. vitaliana along with D. dorsanum shells.
4.1.4.3. Foraminifera. The lower Bessarabian foraminifera assemblage
is less diverse than in Volhynian, but in general, the abundance of in-
dividuals is higher. The most common taxa in SI4 (Figs. 5 and 9A-B) are
Porosononion ex. gr. granosum and P. ex. gr. subgranosum. The difference
between these two species is often very difcult to observe. In addition,
N. bogdanowiczi appears frequently. Elphidium is not as common as in the
previous stratigraphic interval, being identied by rare specimens of
E. crispum and E. hauerinum species. Miliolids are represented mainly by
Pseudotriloculina ex. gr. consobrina and Varidentella sarmatica.
Fig. 8. Calcareous nannofossils from the Karagiye outcrop. 1. Coccolithus miopelagicus, sample KD22-88, 17.5; 2, 3. Coccolithus pelagicus, sample KD22-27, 11.4 m; 4.
Calcidiscus leptoporus, sample KD22-88, 17.5 m; 5, 6. Holodiscolithus macroporus, sample KD22-23, 11 m; 7. Reticulofenestra pseudoumbilicus, morphotype >7
μ
m,
sample KD22-88; 8. Reticulofenestra pseudoumbilicus, morphotype 5–7
μ
m, sample KD22-23, 11 m; 9. Sphenolithus moriformis, sample KD22-88, 17.5 m; 10. Rhab-
dosphaera clavigera, sample KD22-23, 11 m; 11, 12. Discosphaera tubifera, sample KD22-23, 11 m; 13, 14. Rhabdolithus siccus, sample KD22-23, 11 m; 15. Umbil-
icosphaera rotula, sample KD22-23, 11 m; 16. Helicosphaera euphratis, sample KD22-23, 11 m; 17. Pontosphaera discopora, sample KD22-23, 11 m; 18. Pontosphaera
desuetoidea, sample KD22-23, 11 m; 19, 20. Syracosphaera sp., sample KD22-23, 11 m; 21. Helicosphaera wallichii, sample KD22-23, 11 m; 22. Nivisolithu vrabacii,
sample KD22-23, 11 m; 23, 24, 29, 30. Nivisolithus kovacicii, sample KD22-23, 11 m; 25, 26. Syracosphaera fragilis, sample KD22-23, 11 m; 27, 28. Braarudosphaera
bigelowii, sample KD22-23, 11 m. The scale bar applies to all gured fossils.
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Fig. 9a. Volhynian-Bessarabian foraminifera from the Karagiye Section. 1-6. Pseudotriloculina ex. gr. consobrina; 7, 8 Sinuloculina angustioris; 9–12. Quinqueloculina
collaris; 13–20. Varidentella reussi; 21–26. Varidentella latelacunata; 27–28. Varidentella sarmatica; 29, 30. Spiroloculina tenuiseptata; 31, 32. Varidentella rosea; 33–37.
Articulina problema; 38–40. Fissurina cubanica; 41–43. Fissurina bicaudata; 44–46. Fissurina bessarabica; 47–49. Fissurina carpathica; 50–52. Fissurina elongata; 53–54.
Fissurina sp.; 55. Fissurina daraensis; 56–59. Guttulina austriaca; 60, 61. Bulimina elongata; 62–65. Ammonia ex. gr. beccarii; 66–71. Nonion bogdanowiczi; 72–76.
Porosononion ex. gr. granosum.
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Fig. 9b. Volhynian-Bessarabian foraminifera from the Karagiye Section. 1-7. Porosononion ex. gr. subgranosum; 8–14. Porosononion hyalinum; 15–20. Elphidium
crispum; 21,22. Elphidium antoninum; 23–25. Elphidium chtellianum; 26–29. Elphidium hauerinum; 30,31. Elphidium aculeatum; 32–34. Elphidium josephinum; 35–37.
Elphidium reginum var. caucasica.
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4.1.4.4. Ostracods. In contrast to the previous interval, the lower Bes-
sarabian ostracod assemblage is low in diversity and abundance. Only in
the lower part (25.1–44 m), we identied a few to common specimens of
Amnicythere tenuis and very rare Euxinocythere marginata, E. sp. 1 and E.
sp. 2. as well as the loxoconchid species Loxoconcha subcrassula and
Loxoconcha schmidi. The upper part of SI4 (44–65 m), contains almost no
ostracods, except for the sample at 54 m where we identied E. ex. gr.
praebosqueti in large abundance.
4.1.4.5. Nannofossils. Samples from the lower part of SI4 (25.2–44.2 m)
contain nannofossil assemblages dominated by Calcidiscus leptoporus,
C. tropicus, C. pataecus, Coronosphaera sp., small reticulofenestrids
(Reticulofenestra minuta, R. minutula, R. haqii) and Sphenolithus mor-
iformis (highest amounts in samples from 25.4 m to 25.6 m). Allochth-
onous nannofossils point to reworking from the Upper Cretaceous and
Paleogene. Two levels with common diatoms were observed at
46.3–48.5 m and 54–58.4 m. Samples above these levels are barren of
calcareous nannofossils.
4.1.5. Stratigraphic interval 5 (upper Bessarabian, 65–93.2 m)
4.1.5.1. Lithology. Description: SI5 is built up by carbonate rocks with
medium-to thickly-bedded alternation of white, pale yellow parallel-
laminated to wave-ripple cross-laminated ooidic and bioclastic grain-
stones and massive wackstones and packstones with ooids and mollusc
bioclasts (Fig. 2H); Frequent are up to 1m-thick beds of white mud-
stones, locally pierced by horizontal and vertical branched burrows. The
packstones and grainstones are often followed by greenish grey to beige
thinly parallel laminated bindstones (Fig. 2I). There are also occasional
up-to-0.5-m-thick beds of white to beige bioclastic rudstones and fra-
mestones formed by the up-to-1-m-wide and 40-cm-thick bowl-shaped
build-ups of Sinzowella novorossica (Fig. 2G). All the beds show sharp,
straight, locally slightly undulating contacts. SI5 ends with a remarkable
succession represented by highly bioturbated mudstones gradually
coarsening upwards into a massive pink medium-grained grainstone.
Interpretation: The sudden switch from clay-prone SI4 to the
carbonate-dominated depositional settings of SI5 indicates a pro-
gradation of the shallow water nearshore carbonate settings, potentially,
due to a relative water-level fall. The horizontally laminated to wave
ripple-cross laminated oolites were formed as barriers within the car-
bonate platform margins, where the depositional processes are strongly
controlled by the wave-driven oscillatory currents (Burchette, T. P.
et al., 1990; Reading, 1996). The rare foraminifera colonies (frame-
stones) and bindstones represent patch reefs and carbonate mounds
respectively – both developed in the low-energy carbonate platform
interior (Reading, 1996; Tucker, 1985).
4.1.5.2. Mollusc fauna. Based on mollusc distribution, ve units are
recognised with decreasing taxonomic richness (12-10-9-7-2 taxa from
5a to 5e, Fig. 3).
Unit 5a (KDM 66.1─KDM 68.9 m, Fig. 3) shows repetitive alterna-
tion of limestones and marlstones. In the lower part of Unit 5a, the
marlstones comprise loose shells and densely packed shell-debris con-
centrations. In the upper part they become thinner or absent, contrib-
uted by pavements of S. podolica or lenses with small Obsoletiformes sp.
partly in buttery position. Limestone beds can bear large gastropod
shells of Barbotella hoernesi and articulated bivalve shells of S. vitaliana.
The unit is marked by regular presence of S. podolica, Musculus cf.
naviculoides and Obsoletiformes sp. The latter taxon, together with
S. vitaliana and P. tricuspis commonly dominates the assemblages in the
samples. Unit 5a itself marks the lowermost occurrences of B. hoernesi
and Plicatiformes ttoni in the section.
Unit 5b (KDM 69.3─KDM 74.8 m, Fig. 3) is marked by a continuous
presence and the topmost occurrence of Paradonax lucidus. The latter
species is always found together with Obsoletiformes sp. and mostly also
by S. vitaliana and Solen subfragilis. The lowermost sample (KDM 69.3,
Fig. 3) bears random shells and lenses of small Obsoletiformes sp., partly
in a buttery position. The following sample (KDM 71.15 m, Fig. 3)
represents a single pavement with P. vitalianus, sole shells of the latter
species in living position, as well as a shell-concentration comprising
additionally S. vitaliana and P. tricuspis. The third sample (KDM 73.2 m,
Fig. 3) displays shell-debris similar in content to the last one except for
showing no dominant species. The topmost sample (KDM 74.8 m, Fig. 3)
marks the base of a 1-m-thick interval of thinning upward (5–1 cm)
shell-debris interlayers, bearing disarticulated large-sized shells of
common P. tricuspis and Obsoletiformes sp. followed by B. hoernesi and
S. vitaliana, among others.
Unit 5c (KDM 76.2─KDM 79.3 m, Fig. 3) is marked by the regular
and common presence of S. podolica. Additionally abundant are
P. vitalianus and P. tricuspis in the lowermost and S. fabreana in the
topmost sample (KDM 79.3 m). The unit shows frequent shell concen-
trations mostly preserved as steinkerns. Two such 20-cm-thick, reddish-
coloured shell beds are prominent markers, the lower one directly un-
derlying the Sinzowella novorossica bioherm at 78 m, the upper one
marking the sample KDM 79.3 m. They show densely packed unsorted
shell material with B. hoernesi and large horizontally oriented S. fabreana
valves.
Unit 5d (KDM 83.8─88.7 m, Fig. 3) built of various limestone facies,
is marked by a continuous presence of P. ttoni and Obsoletiformes sp.
The latter taxon dominates the assemblage, commonly associated with
S. subfragilis and S. podolica. Additionally, P. vitalianus, S. vitaliana and
M. naviculoides occur. The lowermost mollusc bearing interval (KDM
80.5 m) is a 40-cm-thick shell concentration made by loosely distributed
horizontally oriented valves and valve lenses in nely bedded marly
limestone. The next one (KDM 83.8 m), superposing a stromatolite
bearing interval, represents a 30-cm-thick composite coquina made by a
succession of thin pavements of small-sized Obsoletiformes sp. valves.
The next interval represents occasional bivalve shells and pavements
associated with microbiolithic bindstones (KDM 85.10─85.95 m).
Finally, in a 2-m-thick horizon marked by the presence of serpulid and
bryozoan buildups, the shells-concentrations are represented as thin
singular pavements on bedding planes as well as densely packed co-
quinas with horizontally oriented valves (KDM 87.1─88.7 m). Except for
the lowermost interval, the shells are regularly preserved as steinkerns.
Finally, the topmost Unit 5e (KDM 93–KDM 93.2, Fig. 3), dominated
by light-coloured ooidal limestones, is barren of molluscs. The only
exception is its very top, where a 20-cm-thick pink shell concentration
by randomly distributed shells of Obsoletiformes sp., partly in a buttery
position, is present (KDM 93.0 m). Also rare S. vitaliana and P. ttoni are
present. This level marks the topmost occurrence of Bessarabian mollusc
species in the section.
4.1.5.3. Foraminifera. The lower part of SI5 (up to 78 m) displays
Fig. 9c. Volhynian - Bessarabian ostracods from the Karagiye Section. 1-5. Amnicythere tenuis; 1, 3. LV, external view; 2, 4. RV, external view; 5. C, dorsal view; 6–10.
Euxinocythere ex. gr. praebosqueti; 6, 8. LV, external view; 7, 9. RV, external view; 10. C, dorsal view; 11–14. Euxinocythere adelosinaaff. marginata; 11, 13. LV, external
view; 12, 14. RV, external view; 15–20. Euxinocythere sp. 1; 15, 17. LV, external view; 16, 18. RV, external view; 19. C, ventral view; 20. C, dorsal view; 21–26.
Euxinocythere sp. 2.; 27–32. Callistocythere multicristata; 27, 29. LV, external view; 28, 30. RV, external view; 31. C, ventral view; 32. C, dorsal view; 33–38. Euxi-
nocythere aff. naviculata; 33, 35. LV, external view; 34, 36. RV, external view; 37. C, dorsal view; 38. C, ventral view; 39–43. Loxoconcha subcrassula; 39. LV, external
view, female; 40. RV, external view, female; 41. LV, external view, male; 42. RV, external view, male; 43. C, ventral view; 44–46. Loxoconcha aff. subcrassula; 44. C,
view from LV; 45. C, view from RV; 46. C, dorsal view; 47–50. Loxoconcha ex. gr. kochi; 47, 49. V, external view; 48, 50. RV, external view; 51, 52. Loxoconcha
odessaensis; 51. LV, external view; 52. RV, external view; 53–55. Loxoconcha valiente; 53. LV, external view; 54. RV, external view; 55. C, dorsal view.
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almost the same taxa as below, with even more abundant records (Fig. 5
and 5A-C). The association is dominated by Porosononion ex. gr. gran-
osum, P. ex. gr. subgranosum and Nonion bogdanowiczi. The elphidiids
also show an increasing abundance, especially with numerous speci-
mens of E. crispum and less frequent E. josephinum and E. reginum var.
caucasica. Small-sized Fissurina are quite common between 65 and 75 m,
the most abundant being F. carpathica.
Compared to the lower Bessarabian, the upper Bessarabian speci-
mens have larger and more strongly calcied tests, possibly related to
increased calcium carbonate concentration in the water.
The upper part of SI5 (87–93.2 m) is marked by the appearance of the
strongly calcied species Porosononion hyalinum, associated with
numerous specimens of P. ex. gr. subgranosum (with well-calcied tests)
and E. crispum. Also, the elphidiids with well-developed marginal spines
such as E. josephinum and Elphidium reginum reappear in this interval.
The terminal Bessarabian marks the last foraminifera occurrence in the
Karagiye section.
4.1.5.4. Ostracods. The interval characteristic for the upper Bessara-
bian (65–93.2 m) begins with an important diversication and abun-
dance of ostracod species. Most ostracods possess stronger and well-
calcied shells, similar to foraminifera.
Leptocytherids include A. tenuis, E. ex. gr. praebosqueti, E. sp. 1, E. sp.
2 and Callistocythere multicristata. The Aurila genus is represented by the
well-known A. merita and A. mehesi species, with stronger valves that
differ slightly from the Volhynian specimens. New “aberrant” forms like
Aurila angularis and Aurila sp. appear. From loxoconchids, we identied
L. subcrassula, with bigger shells than in the Volhynian, associated with
new occurrences of Loxoconcha ex. gr. kochi, Loxoconcha odessaensis,
Loxoconcha valiente and the “aberrant” Loxoconcha aff. quadrituberculata.
Besides them, we frequently identied Loxocorniculum ornata, possibly
the more robust and ornate variant, the descendent of L. schmidi from the
Volhynian. The xestoleberids are still represented by X. fuscata and
X. glabrescens, together with more arched species attributed to Xestole-
beris aff. castis. At the top of SI5, we noticed the rst occurrence of
Cyprideis ex. gr. pannonica.
During the upper Bessarabian, the ostracod fauna was dominated by
forms, with stronger calcied shells and more diversied ornamentation
than in Volhynian. The shell peculiarities were possibly a result of the
increase in carbonate concentration in the basin. This phenomenon was
also described for molluscs in the Central Paratethys by Piller and
Harzhauser (2005).
4.1.6. Stratigraphic interval 6 (lower Khersonian, 93.2–112.5 m)
4.1.6.1. Lithology. Description: SI6 begins with pale grey sharp-based
rudstone followed by thinly-bedded very-well sorted pale yellowish
brown Chersonimactra rudstones in beds of 5–10 cm occasionally alter-
nating with beds of pink ooidic sandstones and continuous thin (5–10
cm) lenses of intraformational conglomerates (Fig. 2J). Interestingly, all
the beds in this rudstone-oolite-conglomerate alternation gently deepen
landwards. At 103.8 m, the rudstones are suddenly covered by light
greenish grey massive silty claystones that gradually pass upwards into
pale grey sandy marlstones with wave-ripple marks and abundant
Chersonimactra shells. Above is a series of brown to reddish brown
convoluted and pedogenically modied mudstones with rare vertical
rootlets and gradual bases (Fig. 2K).
Interpretation: The very well sorted Chersonimactra rudstones prob-
ably accumulated on the stoss side of the barrier islands formed at the
margin of the carbonate platform. Here, the gentle landwards deepening
and good sorting suggest high-energy unidirectional wave currents. The
poorly sorted ooidic sandstones point to periods of oscillatory wave-
driven currents, while conglomerates represent events of exceptionally
high waves and/or storm events that caused reworking and redeposition
of the barrier sediments. The overlying massive claystone represents a
lagoon followed by the progradation of coastal settings and establish-
ment of the backshore environments with palaeosols.
4.1.6.2. Mollusc fauna. The lower Khersonian interval comprises four
units marked by monotypic occurrences of Chersonimactra species (C. cf.
caspia in 6a, C. bulgarica in 6b and 6c and C. balcica in 6d). From here, up
to the top of the section, the shells are exclusively preserved as
steinkerns.
Unit 6a (KDM 93.3─KDM 94.9 m, Fig. 3) starts over a sharp lower
boundary with grey bioclastic limestones that contain very common but
poorly preserved shells, thus provisory identied as C. cf. caspia.
Already, the very base of the succession is marked by a 30-cm-thick
coquina with chaotically oriented shells (KDM 93.3 m). Above, they
can additionally occur as horizontally oriented partly articulated shells
(KDM 94.9 m) or concentrated in lenses.
Unit 6b (KDM 98.5─101.25 m, Fig. 3) is represented by about 6-m-
thick horizontally-bedded bioclastic rudstone, composed exclusively of
densely packed randomly oriented single C. bulgarica valves.
Unit 6c (KDM 103.2─KDM 103.65 m, Fig. 3) is located directly atop
the previous rudstone. It begins with a 10-cm-thick coquina bed with
horizontally oriented convex up and remarkably large valves and arti-
culated shells of C. balcica (KDM 102.3 m, Fig. 3). Above, a light grey
marlstone interval is intercalated by two 15-cm-thick C. balcica coquinas
with densely packed shells showing no orientation.
Unit 6d (KDM 104.2–KDM 111.7 m) comprises three C. bulgarica
bearing intervals separated by two barren intervals with loading and
water-escape structures and root traces. The lower shell-bearing interval
(KDM 104.2─106.0 m) shows in its lower part shells oating in the
muddy matrix. They are followed by tiny pavements overlain by a 30-
cm-thick coquina comprising convex-up valves and articulated shells
in situ. Following a short barren interval, another 20-cm-thick coquina
with convex-up valves is present. The 70-cm-thick middle mollusc in-
terval (KDM 109.50─110.05 m) consists of stacked pavements by
convex-up valves, disturbed by lenses of reworked, partly articulated
shells. Finally, the topmost mollusc interval (KDM 111.50─111.7 m) is a
30-cm-thick interval containing accumulations of small-sized dis-
articulated valves.
4.1.6.3. Foraminifera. No foraminifera have been identied in this
stratigraphic interval, possibly due to a salinity drop below their toler-
ance value (possibly under 9 g/L).
4.1.6.4. Ostracods. The luxuriant ostracod fauna from the upper Bes-
sarabian almost disappears in the Khersonian (Figs. 5 and 9D). Only a
few disparate samples, e.g., at 93.8 m, 106 m and 107 m, contain
Fig. 9d. Volhynian-Khersonian (1–39, 44) and Maeotian (40–47) ostracods from the Karagiye section: 1-5. Loxocorniculum schmidi; 1, 3. LV. external view; 2, 4. RV,
external view; 5. LV, ventral view; 6–10. Loxocorniculum ornata; 6, 8. LV, external view; 7, 9. RV, external view; 10. C, ventral view; 11, 12. Phlyctocythere fragilis; 11.
LV, external view; 12. RV, external view; 13–15. Loxoconcha ex. gr. muelleri; 13. LV, external view; 14. RV, external view; 15. C, dorsal view; 16, 17. Loxoconcha aff.
quadrituberculata; 16. LV, external view; 17. RV, external view; 18, 19. Heterocypris salina; 18. LV, external view; 19. RV, external view; 20, 21. Cyprideis ex. gr.
pannonica; 20. LV, external view; 21. RV, external view; 22–25. Cytherois gracilis; 22. LV, external view, female; 23. RV, external view, female; 24. LV, external view,
male; 25. RV, external view, male; 26–28. Xestoleberis fuscata; 26. LV, external view; 27. RV, external view; 28. C, dorsal view; 29–31. Xestoleberis aff. castis; 29. LV,
external view; 30. RV, external view; 31. C, dorsal view; 32–34. Xestoleberis aff. dispar; 32. C, view from LV; 33. C, view from RV; 34. C, dorsal view; 35–39;
Xestoleberis glabrescens; 35. LV, external view, female; 36. RV, external view, female; 37. LV, external view, ? male; 38. RV, external view, ? male; 39. C, dorsal view;
40–42. Euxinocythere aff. maeotica; 40. LV, external view; 41. RV, external view; 42. C, ventral view; 43, 44. Cyprideis ex. gr. pannonica; 43. LV, external view; 44. RV,
external view; 45–47. Xestoleberis maeotica; 45. C, view from LV; 46. C, view from RV; 47. C, ventral view.
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ostracods. We identied the euryhaline species C. ex. gr. pannonica,
associated mainly with Euxinocythere aff. naviculata, Loxoconcha ex. gr.
muelleri, Xestoleberis sp., X. aff. castis and Heterocypris salina.
Even if the diversity is not great, the respective species appear in
abundance and suggest a more restrictive environment.
4.1.7. Stratigraphic interval 7 (upper Khersonian, 112.5–120 m)
4.1.7.1. Lithology. Description: SI7 is characterised by the repetitive
alternation of the following beds: 1. white, thinly parallel-laminated
(1–2 mm) to wave ripple cross-laminated bindstones in beds of 5–50
cm thick with sharp but blanketing bases; 2. pale grey parallel-stratied
mudstones with abundant intraformational angular clasts of reworked
bindstones. The mudstone beds have sharp to gradual bases and a
thickness of up to 60 cm; 3. Orange-brown to light brown massive to
convoluted and aggregated mudstones. The bases of these beds are
gradual, often demonstrating a ame-like irregular appearance. These
mudstones are rare in the lower part of the unit and become more
pronounced and thicker (up to 40 cm) towards the top (Fig. 2L).
Interpretation: The alternation is characteristic of the shallow water
tidal plain. Here, the bindstone represents a shallow water microbial at
growth within the intertidal zone (Browne et al., 2000). The appearance
of the wave ripple marks represents episodes when the intertidal zone
was periodically submerged and affected by the wave-driven oscillatory
currents (Reading, 1996). The “reworked horizons” with intraclasts
point at a more subaerially exposed part of the tidal plain, where there is
more time for the erosion of previously accumulated intertidal deposits.
The top orange and red mudstone indicate pedogenic modication
within the supratidal zone. Here, the convoluted bedding reects the
rare exceptional episodes of high tides responsible for the soft sediment
deformation in palaeosols.
4.1.7.2. Mollusc fauna. The upper Khersonian starts with the topmost
C. bulgarica occurrence in the section, represented by a shell concen-
tration showing shells in live position at the base of a 50-cm-thick, grey-
coloured bindstone (Unit 7a, KDM 113.25 m, Fig. 3). The interval above
(Unit 7b, KDM 114.90–KDM 117.15 m, Fig. 3) is marked by the mono-
specic occurrence of C. caspia starting with a 15-cm-thick shell-
concentration in light-greyish limestone with densely packed pave-
ments of horizontally, convex-up oriented shells of different growth
stages (KDM 114.9 m). Above, a 1-m-thick whitish marl unit bears
several tiny pavements (KDM 115.77 m). Finally, a 30-cm-thick micro-
bial bindstone shows horizontally oriented valves in its lower and arti-
culated shells in life-position in its upper part (KDM 117.50 m).
4.1.7.3. Microfauna. In all micropalaeontological samples, taken from
this interval, no foraminifera and ostracods could be found.
4.1.8. Stratigraphic interval 8 (lower Maeotian, 120–135.5 m)
4.1.8.1. Lithology. Description: In its lower part (120–124.8 m), SI8 is
composed of brown wave-ripple cross-laminated mudstone alternating
with greenish-grey wave-ripple cross-laminated to convoluted micro-
biolithic bindstones. Reworked horizons and palaeosols are rare. From
124.8 m, several 40 cm thick beds of white, very coarse-grained ooidic
calcarenites are present, normally graded, ning upwards into medium-
grained and with irregular erosive bases. The calcarenites are massive,
with faint planar cross-lamination at the base and rare dunes with planar
cross-lamination in the middle. Upwards, the calcarenites pass into a
pale yellow, 4-m thick small-scale trough cross-laminated oolite fol-
lowed by a 0.5 m thick framestone formed by dome-shaped branched
algae build-ups (Fig. 2M). Above, there is a 3-m thick package of thinly
parallel (1–5 mm) laminated bindstone followed by another pinkish-red
trough cross-laminated oolite. Among oolites, concentrations of
gastropod casts and bivalves are present.
Interpretation: SI8 begins with a small transgression that switched the
depositional environments from the inter-/supratidal to subtidal/inter-
tidal. The wave-ripple cross laminated mudstone was formed under the
active wave oscillatory action, while the thick microbiolites represent
shallower periodically exposed intertidal settings. Starting from 124.8
m, the calcarenites and oolites characterise the switch towards the
barrier settings within the shallow water margin of the carbonate plat-
form. The algae build-ups and stromatolithic bindstones indicate the
low-energy carbonate platform interior (Reading, 1996; Tucker, 1985).
4.1.8.2. Mollusc fauna. In the lower Maeotian interval (Unit 8a, KDM
129.5–KDM 135.8 m, Fig. 3), only two mollusc-bearing horizons have
been detected. The lower one is a 40-cm-thick white oolith bed with
common randomly oriented shells of Potamides taitboutii, accompanied
by Lampanella maeotica and single valves of Mytilaster minor (KDM 129.5
m). The upper one, representing the topmost layer in the section, is a
coarse, porous calcarenite with numerous minute shells of P. taitboutii,
M. minor, Loripes pseudoniveus and Ervilia minuta (KDM 135.8 m).
4.1.8.3. Foraminifera. No foraminifera have been identied in the
lower part of the unit, while the upper part was not sampled for
microfauna.
4.1.8.4. Ostracods. Maeotian ostracods have been identied only in a
few samples between 122.1 m and 125.7 m below the oolite bed. The
most characteristic ostracod species are Euxinocythere aff. maeotica, C.
ex. gr. pannonica. L. ex. gr. muelleri and Xestoleberis maeotica.
4.1.8.5. Nannofossils. One investigated sample from SI8 contains a
bloom of Perforocalcinella fusiformis (ascidians; common name sea
squirts). These benthic tunicates commonly occur in shallow marine
environments. No other nannofossils were detected. Perforocalcinella
fusiformis was originally described from the lower Pannonian at Mecsek
Mt., Hungary (Bona, 1964), but is also known from the Sarmatian and
Badenian (Mandic et al., 2019a; Galovi´
c, 2014).
4.2. Vertebrate fauna
The vertebrate nds are grouped and presented by their stratigraphic
occurrences and the position of the nding: in layers (in situ) or in debris
(ex situ) (Table 1). The fossil material has different distribution and
abundance in different beds (e.g. marlstones, shell-beds, conglomerates)
characterising different depositional processes (e.g. accumulations in
lagoons, storm deposition). The shell-beds and conglomerates provide
the highest number of reworked fossils, whereas the marlstones contain
sporadically appearing mostly isolated single bones. Most of the nds
are from the outcrop surface (ex situ), so only their approximate strati-
graphic positions are available. In these cases, the ndings could come
from the overlying (younger) beds and stratigraphic interpretations are
limited.
4.2.1. Fishes
The overall sh diversity has been estimated based on the dentary
bones. This bone is the most commonly found and abundant element in
the Karagiye fossil record. In situ ndings are limited and can be sum-
marised as follows (Table 1): two sciaenids in Konkian; a sciaenid, a
perciform and a sparid in Volhynian; a sparid, a gobiid and a probable
scombrid in Bessarabian (Fig. 10); only fragmentary material from the
micropalaeontological samples in Khersonian. In addition, the Konkian-
Bessarabian micropalaeontological samples include rich otolith mate-
rial. The ex situ nds (Table 1), include Pre-Konkian (debris) sharks
(Selachia indet.) and a sciaenid, Konkian (debris) sharks, two sciaenids,
sparids, three perciform species, Bessarabian (debris) a sparid and a
perciform. In the Khersonian, one micropalaeontological sample (at 115
m) contained unidentiable bone sh fragments, the other samples from
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22
Khersonian-Maeotian beds provided no sh remains.
4.2.2. Marine mammal fauna (whales, dolphins, seals)
4.2.2.1. Konkian. The in situ Konkian forms include: three baleen
whales Imerocetus cf. karaganicus, Zygiocetus cf. nartorum and a Ceto-
theriidae indet. (Fig. 10); an unidentied dolphin Kentriodontidae
indet.; a new form of a seal Phocinae indet. represented by isolated
bones and a partial skeleton, respectively.
The ex situ nds (Pre-Konkian and Konkian debris) include:
numerous isolated bones of a baleen whale Otradnocetus virodovi; several
forms of toothed whales as Kentriodon fuchsii, other unidentied mem-
bers of Kentriodontidae and ?Eurhinodelphidae indet. families and a
partial skeleton of Pachyacanthus suessi; two seals Praepusa sp. and
Phocinae indet. It should be stressed that their Konkian ex situ could be
equally originated from the overlying (Volhynian) beds and (consid-
ering the large bone size and weight) be transported downslope during
weathering processes. Thus, eventual Konkian occurrences of
O. virodovi, P. suessi and K. fuchsii need to be further tested by in situ
nds.
4.2.2.2. Volhynian. The Volhynian in situ nds comprise two whale taxa
Cetotheriidae indet. and Mysticeti indet. and one kentriodontid dolphin
(Table 1). The ex situ nds are very diverse and include more than ten
forms. Among baleen whales, Otradnocetus virodovi is the most abun-
dant. Other whales include several morphotypes of undetermined
members of Cetotheriidae, the most similar to Kurdalagonus mchedlidzei,
an unnamed whale similar to Herpetocetus or Metopocetus genera tenta-
tively identied herein as Herpetocetinae indet.; Mysticeti indet. rep-
resented by vertebrae of a small unknown whale similar to “Archaeocetus
fockii”. The toothed whales, i.e. dolphins, are present with abundant
remains of Pachyacanthus suessi, a diverse kentriodontid with at least
ve taxa (Fig. 10): Kentriodon fuchsii, Sophianaecetus commenticius,
Imerodelphis thabagarii, a large dolphin similar to “Heterodelphis” leio-
dontus and a dwarf dolphin Kentriodontidae indet. (comparable with
“Phocaena” euxina or Microphocaena podolica. The seals are present by
Praepusa sp. and a Phocidae indet.
4.2.2.3. Bessarabian. In the Bessarabian beds, two seals (Praepusa sp.,
Phocidae indet.), a cetotheriid baleen whale and two toothed whales
(Kentridon fuchsii, Odontoceti indet.) were found. The Bessarabian sur-
face nds include Pachyphoca sp., Cetotheriidae indet. and Ken-
triodontidae indet.
The Khersonian and the Maeotian layers do not contain any marine
mammalian remains.
4.3. Magnetostratigraphy
4.3.1. Rock magnetism
The natural remanent magnetisation (NRM) measurements showed
that the Karagiye sediments have a relatively low intensity varying be-
tween 200 and 400
μ
A/m (Supplementary 2). Consequently, the deter-
mination of the magnetic mineral carriers performed with the Curie
balance resulted in a series of hyperbola-shaped curves (Fig. 11A and B)
characteristic of paramagnetic behaviour (Mullender et al., 1993; van
et al., 2016b). In the interval with red rootled mudstone (110.5–111.5
m, SI7), three samples demonstrated a high NRM of up to 17000
μ
A/m.
The thermomagnetic runs show a slightly concave curve with irrevers-
ible cooling curves gently going down to 580 ◦C but keeping part of the
magnetisation up to 700 ◦C (Fig. 11C). Such behaviour is characteristic
of ferromagnetic minerals (Mullender et al., 1993) that considering the
major unlocking temperatures of 580 ◦C and 700 ◦C represent magnetite
and a minor admix of hematite.
Thermal demagnetisation of IRM samples revealed three distinct
groups. The rst group, represented by various Konkian, Volhynian and
Bessarabian carbonate facies (from wackstones to ooidic grainstones),
shows all three coercivity fractions. They display a remarkable reduction
at 330 ◦C indicative for pyrrhotite followed by gradual decline and
demagnetisation at 580 ◦C indicating magnetite as the main magnetic
mineral (Fig. 11C) (Dekkers, 1989; O’Reilly, 1984). In the second group,
samples from relatively deep-water Bessarabian claystones (SI3), all
three orthogonal components gradually decay towards 580 ◦C, sug-
gesting only magnetite (Fig. 11D). The third group, sampled from
Khersonian red mudstones (SI6), show gradual demagnetisation of all
three coercivity components towards 660 ◦C, followed by a sharp drop at
680 ◦C pointing to hematite as the major magnetic carrier (Fig. 11E)
(Lowrie, 1990). Overall, in most samples, the magnetite is the main
magnetic mineral carrier (Supplementary 1).
Table 1
Summary of the marine vertebrate fauna (shes and marine mammals) from the Karagiye Section.
Strat. stage sh seals baleen whales toothed whales/dolphins
otolith-based skeleton-/tooth-based
Maeotian – – – – –
Khersonian –Teleostei indet. – – –
Bessarabian –Sparidae indet.; Gobiidae
indet.; Scombridae indet.;
Perciformes indet. 4
Praepusa sp.;
Phocidae indet.
Cetotheriidae indet. Kentriodon fuchsii; Odontoceti indet.
Bessarabian
debris
–Sparidae indet.; Perciformes
indet. 4
Pachyphoca sp. Cetotheriidae indet. Kentriodontidae indet. Odontoceti indet.
Volhynian –Sciaenidae indet. -Cetotheriidae indet.; Mysticeti
indet.
Kentriodontidae indet.
Volhynian
debris
Sciaenidae indet. 1 (?
Trewasciaena);
Sciaenidae indet. 2
Sparidae indet. Praepusa sp.;
Phocidae indet.
Kurdalagonus cf. mchedlidzei;
Otradnocetus virodovi;
Herpetocetinae indet.;
Cetotheriidae indet.; Mysticeti
indet.
Pachyacanthus suessi; ?“Heterodelphis”
leiodontus; Imerodelphis thabagarii;
Kentriodon fuchsii; Sophianaecetus
commenticius; Kentriodontidae indet.
Konkian Sciaenidae indet. 1 (?
Trewasciaena);
Sciaenidae indet. 2
Perciformes indet. 3 Phocidae indet. Imerocetus cf. karaganicus;
Zygiocetus cf. nartorum;
Cetotheriidae indet.
Kentriodontidae indet.
Konkian
debris
Sciaenidae indet. 1 (?
Trewasciaena);
Sciaenidae indet. 2
Selachia indet.; Sparidae
indet.; Perciformes indet. 1;
Perciformes indet. 2;
Perciformes indet. 3
Praepusa sp.;
Phocinae indet.
Otradnocetus virodovi;
Cetotheriidae indet.
Pachyacanthus suessi; Kentriodon fuchsii;
Kentriodon sp.; ?Eurhinodelphidae indet.
Kentriodontidae indet.
Pre-Konkian
debris
Sciaenidae indet. 1 (?
Trewasciaena)
Selachia indet.; Perciformes
indet. 1
Praepusa sp.
Phocidae indet.
Imerocetus cf. karaganicus;
Otradnocetus virodovi;
Cetotheriidae indet.
Pachyacanthus suessi; Kentriodontidae indet.
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Thermal demagnetisation of 344 samples showed the presence of
two magnetic components. The low-temperature component (LT)
demagnetised at temperatures between 230 and 280 ◦C (on average
around 230 ◦C) and has positive inclination values (Fig. 11F–H). The LT
component mean direction has parameters of declination (D) =4.62◦,
inclination (I) =57.13◦, distribution parameter of Fisher (1953) (k) =
21.98, 95% cone of condence (
α
95) =1.9 for a number of accepted
samples (N) =260 in geographic coordinates (Fig. 11I). The
low-temperature component is usually linked to the current-day
magnetic overprint. The modern magnetic eld in the Karagiye section
has parameters of D =7.58◦and I =63◦(https://www.ngdc.noaa.gov/
for April 2023). Therefore, we interpret the LT component as a
modern-day magnetic overprint complicated by viscous remanent
magnetisation.
The second magnetic component commonly demagnetises between
250 and 400 ◦C (for rare samples with magnetite/hematite, at 690 ◦C)
and has both normal (HT_N) and reversed (HT_R) inclination directions.
The mean direction for the HT_R component has parameters of D =
Fig. 10. Marine vertebrate fauna (1-10. shes and 11-26. marine mammals) from the Karagiye Section. 1, 2. dentary of Perciformes indet. 1 (K23-2), Konkian debris;
3, 4. dentary of Perciformes indet. 2 (KG23-18), Konkian debris; 5, 6. dentary of Perciformes indet. 3 (KG1-213), Konkian debris; 7, 8. dentary of Perciformes indet. 4
(KG22–13.02), Bessarabian (44 m); 9, 10. dentary of Scombridae indet. (KG22-1), Bessarabian (44 m); 11. lumbar vertebra of Pachyacanthus suessi (KG22-05),
Konkian debris; 12, 13. periotic of Kentriodon fuchsii (KG23-1), Volhynian debris; 14, 15. periotic of Sophianaecetus commenticius (KG21-1), Volhynian debris; 16, 17.
periotic of Kentriodontidae indet. (K23-9a), Konkian debris; 18, 19. periotic of Kentriodontidae indet. (KDFs-23-1c), Bessarabian debris; 20. humerus of Imerodelphis
thabagarii (KG1-141), Bessarabian debris; 21. vertebra of Odontoceti indet. (KDFs-23-1c), Bessarabian debris; 22. periotic of Kurdalagonus cf. mchedlidzei (K23-6),
Volhynian debris; 23. tympanic bulla of Zygiocetus cf. nartorum (K23-15), Konkian debris; 24. humerus Praepusa sp. (KDFs-23-1b), Bessarabian debris; 25. lumbar
vertebra of Imerocetus cf. karaganicus (K23-10), Konkian, 12 m; 26. hyoid of Otradnocetus virodovi (unnumbered), Konkian debris.
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(caption on next page)
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Marine and Petroleum Geology 173 (2025) 107288
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186.26◦, I = − 48◦, k =10.18,
α
95 =5.32 for N =77, while for HT_N
component D =2.04◦, I =41.22◦, k =11.05,
α
95 =4.41 for N =102,
both in tectonic coordinates (Fig. 11J and K). These parameters
demonstrate that the LT component is clearly distinguishable from the
HT_N. The reversal test of McFadden and McElhinny (1990) applied to
both HT_N and HT_R is positive (Fig. 11L), and, thus, we interpret the
high-temperature component as characteristic of the sedimentation age.
4.3.2. Polarity patterns
Out of 344 measured samples, 22 samples (~7%) had no magnetic
signal (diamagnetic), 91 samples (~26%) have undetermined (grey in
Fig. 12) directions, 159 samples (~46%) have directions with mean
angular deviation (MAD) less than 15◦, 34 samples (~10%) have MAD
between 15 and 20◦and 38 samples (~11%) have MAD exceeding 20◦
(Fig. 8, Supplementary 1). Conventionally, only directions with MAD
<15◦are considered reliable (Butler, 1992). The higher MADs likely
result from the low NRM of the sediments, and make polarity in-
terpretations less straightforward. Considering that the
high-temperature component passes the reversal test, we tend to accept
all directions up to MAD ≤20◦and we use directions with MAD >20,
only to support polarity interpretation of questionable intervals.
The polarity patterns of the studied outcrop comprise 18 polarity
zones with nine normal (N1–N9) and nine reversed (R1–R9) (Fig. 11).
The measurements of three samples from SI1 (Maykopian) did not
deliver reliable results; likely due to the chemical alteration of the
sediments (e.g. jarosite powder standing for oxidation of suldes). The
Konkian begins with a series of undetermined directions (8.8–10.5 m)
followed by a short normal zone N1 (10.5–13 m) and a reversed zone R1
(13–13.9 m). The Volhynian shows a sharp polarity change towards
normal (zone N2, 13.9–16.2 m), followed by reversed zone R2
(16.2–18.1 m), after which the sample directions are indeterminate
between 18.1 and 19 m. The normal directions in the remaining upper
part of SI3, between 19 and 25 m, form normal polarity zone N3.
The lower Bessarabian (SI4) comprises a long reversed zone R3
(25–50.1 m), among which there are three single normal samples (26.4,
34.65 and 45.5 m). Between 50.1 and 52.9 m, sample polarity uctuates
and thus is uncertain. At 52.9 m, a long normal polarity zone N4 begins,
extending into upper Bessarabian (SI5) until 88 m. Within the N4, there
are two single reversed polarity samples (75.3 and 82.1 m). Above the
N4, between 88 and 90.85 m, there is a series of four reversed samples:
three with high and one with low MAD. We interpret this interval as
reversed zone R4. Above is a normal zone N5 that passes into the lower
Khersonian (SI6) and lasts up to 96.25 m. Between 96.25 and 96.6 m,
two reversed samples are situated within a thick package of normally
magnetised rudstone. Considering active sedimentary processes within
this body, we interpret these two samples as remnants of a small
reversed zone R5 (with a question mark). Above lies the normal polarity
zone N6 (96.6–101.4 m), which is followed by long reversed polarity
zone R6 (101.4–112.5 m) with two single normal polarity samples
(107.9, 110.5 m).
The upper Khersonian (SI7) begins with a normal polarity zone N7
(112.5–119.25 m) followed by a short reversed polarity zone R7
(119.25–119.75 m). The Maeotian (SI8) begins in the lowermost part of
a normal polarity zone N8 (119.75–121.8 m) followed above by
reversed zone R8 (121.8–123.9 m) and normal zone N9 (123.9–125.2
m). Higher up, the polarity becomes less clear; apparently, fragile
bindstones and framestones were unsuitable for palaeomagnetic sam-
pling. Between 125.2 and 129, there are three reversed samples, with
two having MAD between 15 and 20. We call this interval the polarity
zone R9. The last measured sample at 129 m has normal polarity.
5. Discussion
The combination of sedimentological observations, high-resolution
palaeomagnetic dating and fossil records of molluscs, microfauna,
calcareous nannoplankton and vertebrates allows us to reconstruct the
palaeoenvironmental evolution of Karagiye and the Caspian Basin and
compare it with other parts of the Eastern Paratethys. The discussion
below is built stage-wise, focusing on the correlation of the Karagiye
polarity patterns to the GPTS, a comparison of the Karagiye biotic record
with other parts of the Eastern Paratethys and a summary of the effects
of the Miocene hydrological and biotic events on the Caspian Basin.
5.1. Konkian Stage – pre-isolation phase of the Eastern Paratethys
5.1.1. Correlation to the global polarity time scale (GPTS)
The acquired magnetostratigraphic patterns of the Karagiye section
require a cautious correlation to GPTS due to the presence of several
hiatuses in the stratigraphic succession. Except for the Konkian part, the
combination of magnetostratigraphy and biostratigraphy generally
provided solid age constraints (Fig. 13).
The Konkian Stage was previously dated magnetostratigraphically
between 13.4 and 12.65 Ma, by correlation to the C5ABn – C5Ar.1r
chrons in the GPTS (Fig. 13) (Palcu et al., 2017). In Karagiye, the
6-m-thick Konkian deposits display only one polarity switch from a long
normal polarity zone N1 to a short reversed – R1, suggesting an
incomplete Konkian record (Fig. 13). Within this interval, a faunal
change at 12.6 m from assemblages with Barnea ustjurtensis to a faunal
complex with Limacina konkensis (Fig. 3) marks a lower-middle Konkian
(also known as Kartvelian-Sartaganian) biostratigraphic boundary
(Popov et al., 2022). This boundary was magnetostratigraphically dated
in the Zelenskiy-Panagea (Euxinian Basin) at 12.9 Ma, correlating to the
top of the C5Ar.3r reversed chron (Palcu et al., 2017), while in Karagiye
it appears in the upper part of the normal zone N1.
We consider two correlation options. Option 1 correlates the N1/R1
polarity switch to the C5AAn-C5Ar.3r reversal (Fig. 13A). Extrapolation
of the average sedimentation rates of 0.04 m/kyr from the lithologically
similar Volhynian, estimates the base of the Konkian at 13.14 Ma and
the Sartaganian faunal change at ~13.03 Ma. This suggests that the
Sartaganian marine fauna reached the Caspian Basin about 100 ky
earlier than in the Euxinian Basin (e.g. 12.9 Ma, Popov et al., 2022), an
unlikely scenario considering this fauna arrived from the Central Para-
tethyas via the Euxinian Basin.
Option 2 correlates the N1/R1 polarity change to the C5Ar2n-
C5Ar.2r reversal (Fig. 13A). This scenario suggests a delayed arrival of
the marine Sartaganian faunas to the Caspian Sea at ~12.83 Ma, with
the base of the Konkian being ~12.88 Ma. None of the two correlation
options are conclusive.
5.1.2. Comparison of the Konkian biotic record within the Caspian Basin
and with Euxinian Basins
During the Kartvelian, the Karagiye region was characterised by a
sparse faunal assemblage, including the calcareous nannoplankton
Coccolithus pelagicus, the ostracod Cytherois gracilis and the mollusc
Barnea ustjurtensis (Fig. 14). In the neighbouring Terek-Caspian
Depression and Kura Basin, the Kartvelian faunal assemblages are also
Fig. 11. Summary of rock magnetic properties and magnetic components of sediments from the Karagiye outcrop. Curie Balance curve showing: A. paramagnetic
behaviour, B. Demagnetisation of hematite-bearing red mudstones; Demagnetisation curves of orthogonal IRM fractions: C. For pyrrhotite and magnetite-bearing
carbonates (Group 1), D. For hematite-bearing red mudstones (Group 2), E. For magnetite-bearing claystones (Group 3). Representative Zijderveld diagrams after
thermal demagnetisation in tectonic coordinates (tc) for: F. G. Reversed polarity samples, H. Normal polarity samples. Areal plots for: I. Low temperature (LT)
directions in geographic coordinates; J. High temperature reversed (HT_R) and K. High temperature normal (HT_N) directions, both in tectonic coordinates. L.
Cumulative distributions of Cartesian coordinates of means HT_N and HT_R (Bootstrap reversal test of (Tauxe, 2010)). The reverse polarity has been ipped to
antipode. The condence bounds of three components overlap (e.g. cannot be distinguished at 95% of condence) and thus pass the reversal test.
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Fig. 12. Magnetic polarity patterns of the Karagiye section.
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impoverished and contain B. ujratamica, B. ustjurtensis, sh otoliths and
almost no microfauna (Muratov and Nevesskaya, 1986). On the Euxi-
nian side of the Caucasian Foreland (Rioni Basin), the Kartvelian fauna is
more diverse and contains abundant mollusc taxa of Barnea –
B. ustjurtensis, B. ujratamica, B. scrinia, B. kubanica, B. sinzovi, B. bul-
garica, Ervillia pussila and single species of the foraminifera genera
Cassidulina, Discorbis, Elphidium and Ammonia (Jgenti and Maisuradze,
2016). The Euxinian outcrops of Crimea and the eastern part of the
northern Black Sea contain no mollusc fauna but have a foraminifera
assemblage dominated by the genera Cassidulina and Discorbis:
D. kartvelicus, C. bulbiferous, C. bogdanowiczi and rare Varidentella ex gr.
reussi, Ammonia beccarii, Nonion sp., Pseudotriloculina ex gr. consobrina,
Articulina vermicularis, Reussella spinulosa and calcareous nannoplankton
association with Braarudosphaera bigelowii, Calcidiscus leptoporus,
Fig. 13. Correlation of magnetic polarity patterns from Karagiye to the GPTS with a focus on three boundary intervals: A. Kartvelian-Sartaganian (middle-upper
Konkian) with two correlation options, both being non-conclusive; B. Bessarabian-Kehrsonian boundary. Here, both options place the boundary at ~9; 9 Ma, but
Option 1 is favourable; C. Khersonian-Maeotian transition with the boundary placed at 120 m (7.65 Ma).
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Fig. 14. Correlation of the Karagiye polarity pattern to the GPTS. Mollusc, foraminifera and calcareous nannoplankton biozonations, the most characteristic ostracod fauna and marine vertebrate fauna diversity trends
are correlated to major Paratethyan hydrological and biotic events. References: 1 - (Popov, 2004), 2 - (Paramonova, 1994), 3 - (ter Borgh et al., 2014), 4 - (Palcu et al., 2015).
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Coccolithus pelagicus, Cyclicar golithus oridanus, Pontosphaera multipora
and Reticulofenestra pseudoumbilicus (Palcu et al., 2017; Vernyhorova,
2015, 2018; Krasheninnikov et al., 2003; Popov et al., 2016).
A massive Sartaganian faunal inux brought to Karagiye several
mollusc taxa such as Varicorbula gibba, Aporrhais alata and Limacina
konkensis, rich foraminifera assemblage with the dominance of Bolivina
dilatata, Bulimina elongata, B. subulata, Porosononion marktobi, Quinque-
loculina tortonica, Q. irregularis, Q. akneriana, Q. gracilis, Anetrina col-
laris and Pseudotriloculina consobrina etc. (Fig. 6A). The Sartaganian
ostracod assemblage is represented by Cytherois gracilis, Cythereis cau-
casica, Olimphalunia plicatula and Sclerochilus sp. (Fig. 6B). Cythereis
caucasica has been described by Schneider (1939) from the Tarkhanian
and Chokrakian of the Western Caucasus (Taman Peninsula). It has also
been observed in the Konkian of the Western Black Sea, (Tuzlata section,
Bulgaria) (M. Stoica unpublished results). However, it never appeared in
the Central Paratethys. Cytherois gracilis was described by Schneider
(1949) from the Karaganian deposits of Azerbaijan. In the Central Par-
atethys, this species is well known and frequently occurs during the
Sarmatian s. str. under the name Cytherois sarmatica (Jiˇ
riˇ
cek, 1974). The
latter name, in our opinion, should be considered a junior synonym of
C. gracilis. Olimfalunia plicatula is a common species recorded in the late
Badenian of the Central Paratethys, described by Reuss in the Viena
Basin (see also Gross, 2006). In addition, it is mentioned in the Dacian
Basin (Olteanu, 2006), as well in the northern Black Sea (North Caucasus
and Crimea) by Schneider (Schneider, 1939, 1949), under the name
Cythereis tschokrakensis. The Sartaganian deposits of Karagiye also
contain rich calcareous nannoplankton with Braarudosphaera bigelowii,
Coccolithus pelagicus, Holodiscolithus macroporus, Rhabdosphaera sicca,
Reticulofenestra pseudoumbilicus and Syracosphaera mediterranea (Fig. 8),
which based on the absence of Sphenolithus heteromorphus can be
attributed to the NN6 biozone ( ´
Cori´
c et al., 2023). Moreover, Sartaga-
nian samples from Karagiye contain endemic Nivisolithus kovacici and
N. vrabacii, originally described from the time-equivalent late Badenian
of the Central Paratethys (Bukova Glava, Krndija Mountain, Croatia)
(´
Cori´
c et al., 2023), suggesting an active water exchange and similar
hydrological conditions across the entire Paratethys domain.
Compared to the other parts of the Caspian Basin, the Sartaganian
faunas of Karagiye appear to be taxonomically poorer. In the Terek-
Caspian Depression, in addition to the mollusc forms present in Kar-
agiye, there are also Davidaschvilia sokolovi, Abra alba, Timoclea kon-
kensis and Nassarius Dujardin (Muratov and Nevesskaya, 1986). In the
Kura Basin, the biodiversity is higher and, in addition to listed Karagiye
taxa, includes molluscs Mactra basteroti, Aequipecten malvinae, A.
diaphanus, Anomia ephippium, Europicardium multicostatum, Acantho-
cardia paucicostata, A. andrussovii, Cochlis cf. millepunctata and fora-
minifers Angulogerina angulosa, Uvigerina gracilissima, Borelis (Muratov
and Nevesskaya, 1986; Jgenti and Maisuradze, 2016; Rostovtseva et al.,
2020).
The Sartaganian fauna of the Euxinian Basin comprises most of the
mentioned Caspian fauna but with addition of many other forms: Ana-
dara turonica, Polititapes vitalianus, Plicatiformes praeplicatus, Ervilia
pusilla trigonula, Obsoletiformes ruthenicus, Retusa sp., Cochlis cf. mil-
lepunctata molluscs (Muratov and Nevesskaya, 1986), dominant steno-
haline foraminifers of genera Lagena, Nodobaculariella, Spirolina,
Globulina, Virgulina, Reussella, Pyrgo (Vernyhorova, 2018; Kra-
sheninnikov et al., 2003) and nearly identical calcareous nannoplankton
assemblage (Radionova et al., 2012).
5.1.3. Konkian palaeoenvironment in Karagiye and its response to the
Eastern Paratethys – global ocean connectivity dynamics
During the Konkian, the Eastern Paratethys was mostly connected to
the global ocean via the Barlad and Carasu Straits – Central Paratethys –
Slovenian Strait, although experiencing episodes of pronounced hy-
drological restriction (Fig. 14) (Popov, 2004; Popov et al., 2022; Stu-
dencka et al., 1998). However, the connection with the Central
Paratethys was not strong enough to allow a uniform distribution of
planktonic foraminifera and radiolarians. At that time, the Caspian Basin
was connected with the Euxinian (Black Sea) Basin in the south via the
Transcaucasian Strait (Kura and Rioni basins) along the Caucasian
Foreland and in the north along the Forecaucasus (Caspian-Terek
Depression and Scythian Shelf).
During the Kartvelian, the Karagiye area was occupied by a large
open lagoon/shallow littoral zone subject to oscillatory wave action and
probably small tidal activity. With the dominance of Barnea molluscs,
rare calcareous nannoplankton and impoverished foraminifera fauna,
both in Karagiye and the neighbouring parts of the Caspian Basin, the
Kartvelian palaeosalinity can be estimated as polyhaline. The Eastern
Paratethys connection with the global ocean was limited as revealed by
the basin-wide development of a poor faunal assemblage dominated by
the endemic Barnea species and impoverished foraminifera fauna
(Jgenti and Maisuradze, 2016; Popov et al., 2022).
Comparing the Kartvelian biotic records between the Caspian and
Euxinian basins demonstrates a remarkable westward biodiversity in-
crease, which is likely linked to the presence of a salinity gradient
throughout the Eastern Paratethys, with the Euxinian Basin being saltier
than the Caspian Basin. The Euxinian Basin, as the closest to the Carasu
Strait, received more marine inow, while in the remote Caspian Basin,
the riverine inux played a more prominent role in the basin salinity.
A massive faunal inux marks the onset of the Sartaganian substage.
In Karagiye, this event was not accompanied by any changes in the
depositional environments, with the open lagoon settings persisting
further.
During the Sartaganian, the Eastern Paratethys connection with the
global ocean was restored, which facilitated the invasion of numerous
euhaline faunal groups (Vernyhorova, 2018; Popov et al., 2022). The
occurrence of rich euhaline fauna far east, in the Caspian Basin shows
that even the most distal parts of the Eastern Paratethys turned to full
marine conditions.
5.2. The Volhynian (sub)stage – the onset of isolation of the Eastern
Paratethys
5.2.1. Correlation to the GPTS
The base of the Volhynian is synchronous with the base of the Sar-
matian s.s. in the Central Paratethys and has an age of 12.65 Ma, which
correlates to the middle of C5Ar.1r (Palcu et al. 2015, 2017; Mandic
et al., 2019b). One of the rst attempts to date the
Volhynian-Bessarabian boundary was made by Chumakov et al. (1992)
using the ssion track method, who placed the boundary at 12.2 Ma.
Later, using the integrated stratigraphic approach (cyclo- and biostra-
tigraphy) for the correlation between the Central and Eastern Para-
tethys, Harzhauser and Piller (2004) estimated the
Volhynian-Bessarabian boundary age at around 11.9 Ma. At the same
time, neither palaeomagnetic nor radiometric age constraints were
performed in the Eastern Paratethys on the Volhynian-Bessarabian
geological records. Considering the mentioned age constraints and
anticipating the Volhynian age to be around 12.6–12 Ma, we correlate
the Volhynian polarity patterns in Karagiye in the following order: the
N2 to C5An.2n, R2 to C5An.1r and N3 to C5An.1n (Fig. 12). Such cor-
relation suggests that a large portion of the Volhynian deposits (reversed
polarity chron C5Ar.1r and the lower part of the normal polarity chron
C5An.2n) is missing at Karagiye. Calculating the average sedimentation
rates from the chrons R2 and N3 (C5An.1r–C5An.1n) results in 0.04
m/kyr. Extrapolation of this rate downwards to the base of the N2 zone
results in an age of 12.33 Ma for the basal Volhynian deposits in Kar-
agiye. Therefore, we interpret the presence of a ~670 kyr gap (between
13.0 and 12.33 Ma) straddling the Konkian/Volhynian boundary in the
Karagiye section.
5.2.2. Volhynian biotic record of the Caspian Basin and its comparison with
the rest of the Eastern Paratethys
The Volhynian fossil record of Karagiye is characterised by a gradual
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diversication towards the top of the record (Figs. 3 and 5). The onset
begins with a few new rotaliid taxa of rare Nonion bogdanowiczi, Elphi-
dium crispum and Elphidum hauerinum foraminifers, Amnicythere tenuis,
Euxinocythere marginata and Loxoconcha subcrassula ostracods and
Obsoletoformes spp., Musculus spp. and Abra spp. molluscs. In addition to
the newly-occurring taxa, several foraminifera taxa such as Quinquelo-
culina haueriana, Q. gracilis, Q. pseudoangustissima and Pseudotriloculina
ex. gr. consobrina and one ostracod species Cythereis gracilis passed from
the Konkian and persisted during the Volhynian.
Further upwards, the mollusc fauna diversies gradually, with the
new taxa Ervilia dissita, Sarmatimactra eichwaldi and Polititapes vitalianus,
while the microfauna expands stepwise: at 15.6 m occur Ammonia bec-
carii, Elphidium crispum, E. hauerinum, Varidentella reussi and Quinque-
loculina collaris; and at 18.20 m – Fissurina carpathica, F. elongata,
Porosononion ex. gr. subgranosum and P. ex.gr. granosum. The most
remarkable Volhynian faunal change in Karagiye happened at 21.3 m,
where Dorsanum duplicatum, Timisia picta and Plicatiformes plicatottoni
molluscs, Fissurina cubanica, F. bicaudata and Elphidium aculeatum, E.
josephinum, E. reginum, Guttulina austriaca foraminifers and Aurila merita,
A. mehesi, Euxinocythere praebosqueti, Loxococncha subcrassula, Lox-
ocornichulum ornata, Xestoleberis spp. ostracods occur.
In the neighbouring regions of the Caspian Basin, the data on the
Volhynian fossil fauna is scarce but generally, resembles those in Kar-
agiye. In the Terek-Caspian Depression, the Volhynian deposits
comprise a similar faunal assemblage with Abra reexa, Sarmatimactra
eichwaldi and deep water Cryptomactra pseudotellina molluscs and Vari-
dentella reussi and Quinqueloculina consorbina foraminifers (Muratov and
Nevesskaya, 1986). In the Kura Basin, similar to Karagiye, the Volhynian
fauna is dominated by the indicative molluscs Polititapes vitalianus,
Ervilia dissita, Abra reexa, Dorsanum duplicatum, Sarmatimactra eich-
waldi with addition of Donax dentiger and other taxa of the genera Tro-
chus, Calliostoma, Gibbula, Solen and Acteocina (Buleyshvili, 1960;
Ali-Zade, 1974). In the outcrops of East Georgia (Kura Basin), the Vol-
hynian foraminifera fauna is typically subdivided into three biozones
(following upwards): Elphidium horridum zone, Varidentella reussi zone
and Elphidium aculeatum zone (also often referred as Elphidium reginum
zone) with the latter two being identical to Karagiye (Koiava et al.,
2008).
In the Euxinian Basin, the Volhynian faunas were studied in more
detail, and the faunal assemblages are similar to the ones documented in
Karagiye. On the Taman Peninsula (Euxinian Basin), the Volhynian is
marked by the mass occurrence of euryhaline molluscs Abra alba scythica
and rarer Ervilia dissita, Obsoletiformes sp., Sarmatimactra eichwaldi and
Musculus sp. The microfaunal assemblages are dominated by Lep-
tocythere, Loxoconcha, Xestoleberis, Aurila, Denticulocythere, Cytherois,
Cythereis and Cyprideis ostracods and Articulina sarmatica, Elphidium
josephinum and Varidentella reussi foraminifers with the latter two
constituting the Varidentella reussi and Elphidium reginum zones (Popov
et al., 2016; Karmishina and Shneider, 1986). During the Volhynian,
both foraminifera and ostracods have many elements in common with
the lower Sarmatian fauna of the Central Paratethys. The Volhynian
calcareous nannofossils in Taman are represented by a very poor
monospecic assemblage with Syracosphaera (Radionova et al., 2012),
which is incomparable with a rich complex documented in Karagiye by
Helicosphaera spp., Braarudosphaera bigelowii, Cocolithus pelagicus,
Reticulofenestra pseudoumbilicus (Figs. 7 and 8).
5.2.3. Volhynian palaeoenvironments in Karagiye – the onset of
hydrological isolation of the EP and its expression in the Caspian Basin
The Volhynian marks the onset of the hydrological isolation of the
Paratethys from the global ocean. This conclusion is based on a sharp
extinction of stenohaline taxa at the Badenian-Sarmatian (in the Central
Paratethys) and Konkian-Volhynian (in the Eastern Paratethys) bound-
aries known as the BSEE (see Chapter 2). A major role in this process was
attributed to the Slovenian Strait, whose termination stopped the marine
inow and led to a basin-wide salinity drop. However, no fauna-
independent geochemical constraints exist to conrm this hypothesis.
Between 12.33 and 12.0 Ma, Karagiye was at the margin of a large
open lagoon with oscillatory wave- and small tidal currents, active
bioturbation and episodes of subaerial exposure. As the upper Konkian –
lowermost Volhynian are missing in the section, it is impossible to es-
timate the impact of the Paratethyan hydrological isolation on the area.
The Volhynian in Karagiye largely misses most of the Konkian fora-
minifers, marine ostracods and, most remarkably, sharks, which likely
points to a salinity decrease (lack of fully marine conditions). At the
same time, four foraminifera taxa, one marine ostracod and, most
importantly, all Konkian nannoplankton taxa passed into the Volhynian.
Comparison of the Volhynian biotic record and biozonation from
Karagiye with the other parts of the Caspian and Euxinian basins shows
the uniformity of Volhynian ecosystems across the Eastern Paratethys,
which is essential for inter-basinal correlations and application of
biozones.
5.3. Bessarabian Stage – from a maximum transgression to the rst
hydrological disruption of the Eastern Paratethys
5.3.1. Correlation to the GPTS
The Bessarabian in Karagiye starts at 25.2 m, marked by a large
transgression event and a rst occurrence of indicative Bessarabian
Plicatiformes plicatottoni molluscs. The Bessarabian palaeomagnetic
record in Karagiye comprises magnetic zones ranging from R3 to the
middle of N5 (Fig. 13). Considering the conformable position of Bes-
sarabian on top of Volhynian, we correlate these zones in the following
order: long reversed zone R3 with three single normal samples is
correlated to the chron C5r (that comprises several short normal polarity
intervals according to Krijgsman and Kent, 2004); long normal zone N4
– to the C5n.2n; reversed one R4 corresponds to the C5n.1r and the
following normal zone N5 correlates to the C5n.1n (Fig. 13).
The Volhynian-Bessarabian boundary is located only a few centi-
metres above the C5An.1n–C5r.3r reversal that has an age of 12.045 Ma.
Such age is generally in line with the age model of Harzhauser and Piller
(2004) who correlated the boundary slightly above the C5An.1n–C5r.3r
reversal. Therefore, we date the Volhynian-Bessarabian boundary at
~12.05 Ma.
5.3.2. Bessarabian fossil record in Karagiye and its comparison with other
parts of the Eastern Paratethys
From the faunal point of view, the Bessarabian deposits in Karagiye
are subdivided into lower and upper intervals (Fig. 14). For the lower
Bessarabian, the most characteristic fauna includes Sarmatimactra
vitaliana, Obsoletiformes spp., Plicatiformes plicatottoni, Ervillia dissita,
Polititapes vitalianus molluscs, Nonion bogdanowiczi, Porosononion gran-
ossum, Elphidium crispum foraminifers, minor presence of Amnicythere
tenuis and Loxoconcha subcrassula ostracods and rich but upwards-
decreasing calcareous nannoplankton assemblage with Calcidiscus
spp., Coronasphaera sp., Reticulofenestra pseudoumbilicus and Sphenolithus
moriformis.
The base of the Bessarabian is marked by an abundant occurrence of
Calcidiscus spp. nannoplankton, resembling similar forms of the Naˇ
sice
section, Croatia (´
Cori´
c, 2006; Galovic and Young, 2012) suggesting
uniform basin-wide ecological conditions.
In the upper Bessarabian, the molluscs fauna is represented by Sar-
matimactra podolica, S. fabreana, Plicatiformes ttoni, Solen subfragilis,
Polititapes tricuspis, Barbotella hoernesi, Paradonax lucidus and minor
presence of Gibbula feneoniana. The upper Bessarabian foraminifera
assemblage is similar to the lower Bessarabian except for the new
Porosononion hyalinum appearing in the very top and other taxa such as
Porosononion ex. gr. granosum, P. ex. gr. subgranosum and Elphidium
reginum becoming abundant. The ostracod fauna shows numerous new
taxa, with Callistocythere sp., Loxoconcha ex. gr. kochi, Cyprideis ex. gr.
pannonica and Loxoconcha aff. quadrituberculata. No nannoplankton was
detected in the upper Bessarabian. Ostracod fauna from the Karagiye
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section is similar to the fauna described from the northern Black Sea,
Caucasus and Caspian areas, although some differences in taxonomic
approach exist (Schneider, 1939, 1949, 1953; Suzin, 1956; Pobedina
et al., 1956; Stancheva, 1990).
Similar to Karagiye, the two-member subdivision of the Bessarabian
into lower (known as the “Novomoscovian layers”) and upper (also
known as the “Dnipropetrovsk-Vasilevka layers”) has been traced across
the Euxinian and Caspian basins of the Eastern Paratethys (Paramonova,
1994). In the stratotypes of Southern Ukraine, the lower Bessarabian
fauna comprises Obsoletiformes obsoletum, Cerastoderma plicatum plica-
tum, Sarmatimactra vitaliana, Calliostoma podolica, while the upper Bes-
sarabian deposits include Plicatiformes ttoni, Sarmatimactra fabreana,
Barbotella intermedia and others (Muratov and Nevesskaya, 1986). In the
Taman Peninsula (Euxinian Basin), Kura Basin and Terek-Caspian
Depression (both in the Caspian Basin), the lower Bessarabian is repre-
sented by deep-water claystone facies, which contains characteristic
deep-water assemblage dominated by Cryptomactra pesanseris,
C. pseudotellina and Sarmatimactra urupica molluscs, rare foraminifers of
the genera Nonion and Elphidium and Reticulofenestra sp. and Coccolithus
pelagicus calcareous nannoplankton (Muratov and Nevesskaya, 1986;
Nevesskaya and Trubikhin, 1984; Popov et al., 2016).
The upper Bessarabian deposits in the Kura Basin and the Terek-
Caspian Depression are represented by shallow water marlstone facies
that contain assemblages similar to Karagiye with Plicatiformes ttoni,
Sarmatimactra fabreana, Ervilia dissita (Muratov and Nevesskaya, 1986).
5.3.3. Bessarabian palaeoenvironments in Karagiye
During the Bessarabian Stage, the Eastern Paratethys reached its
maximum Middle-Late Miocene water level (Fig. 14). The large trans-
gression started at 12.05 Ma and extended far inland, in the direction of
Central Asia and north of the Black Sea (Popov et al., 2022).
In Karagiye, the Bessarabian transgression changed the shallow-
water marginal lagoon environments to relatively deep-water offshore
settings. Remarkably for the Bessarabian, the faunal assemblages
demonstrate a quantitative explosion in the rst meter above the
transgressive contact at 25.2 m. This fauna almost disappeared above 27
m as the water level continued to rise.
The observations on the lower Bessarabian facies in Karagiye show
that the depositional settings uctuated between offshore and offshore
transition. One of the most remarkable transgressive surfaces occurred
at 32.5 m dated at ~11.8 Ma, with the offshore setting lasting up until
41 m or ~11.6 Ma, afterwards switching back to offshore transition
environments. During this time, the water level rise in the Euxinian
Basin reached its maximum as the basin ingressed far north into the
Palaeo-Don Valley, where the Bessarabian transgression was dated at
11.5 Ma (Daniˇ
sík et al., 2021).
At 11.7 Ma (below C5r.2n), the closure of the Iron Gate Strait
separated the Central Paratethys from the Eastern Paratethys and turned
it into a gradually freshening brackish lake (ter Borgh et al., 2014). As
observed in Karagiye, neither the water balance nor the faunal record
was affected by this event.
At 10.67 Ma (65 m), the depositional setting abruptly switched to the
carbonate platform interior, followed by the appearance of new late
Bessarabian faunas. A similar transition from clastic to shallow car-
bonate depositional settings has been previously observed in all other
parts of the Eastern Paratethys, such as the Bulgarian coast of the Black
Sea (Koleva-Rekalova, 1994), Crimea and north of the Black Sea
(Muratov and Nevesskaya, 1986).
We assume that this event, called here the “Intra-Bessarabian Car-
bonate Surge,” was linked to the water-level-drop-related increase in
carbonate saturation. Carbonates were constantly delivered into the
isolated Eastern Paratethys from the surrounding land masses and
mountain ranges (Carpathians, Caucasus). Observations on the micro-
fauna in Karagiye showed a remarkable thickening of ostracod and
foraminifer shells, which indicates a rise in the water alkalinity.
During the late Bessarabian, between 10.7 and 9.9 Ma, Karagiye was
a shallow water carbonate platform interior inhabited by serpulid col-
onies, microbial mats and rich invertebrate faunas.
5.4. Khersonian Stage – onset of hydrological and biotic instability
5.4.1. Correlation to the GPTS
The Khersonian deposits in Karagiye begin at 93.2 m with the rst
occurrence of Chersonimactra cf. caspia and span the N5-N8 polarity
interval (Fig. 13). The transition from the upper Bessarabian (SI5) car-
bonate platform interior grainstones to Khersonian barrier island rud-
stones has an erosional appearance and thus requires cautious
correlation to the GPTS.
The Bessarabian-Khersonian boundary is located in the middle of the
normal zone N5. The following R5 and N6 are located in rudstones
accumulated in high-energy environments, making the chrons thicker
(as for N6) or extremely short/incomplete (as for R5). The R6 spans the
ne-grained lagoon to backshore deposits and is incomplete as it is
followed by a hiatus at 112.5 m.
For the correlation of N5-R6 to GPTS, we discuss two options
(Fig. 13): Option 1 correlates N5 to C5n.1n, R5 to C4Ar.3r, N6 to
C4Ar.2r and R6 to C4Ar.2r. With such correlation, the transition to
rudstones demonstrates a slight increase in the average sedimentation
rates from 0.04 to 0.06 m/kyr. Extremely low sedimentation rates in R5
are in disagreement with observed coarse-grained lithology, which
suggests the incompleteness of the chron. Extrapolation of the 0.04 m/
kyr rates within the N5 zone results in a Bessarabian-Khersonian
boundary age of 9.87 Ma. If extrapolating the sedimentation rates
from R4 up to the boundary (R4 and the lower part of N5 have similar
lithology), the boundary arrives at 9.9 Ma.
The reversed zone R6 has a similar lithology as R4. Extrapolation of
the sedimentation rates of 0.04 m/kyr from R4 to the R6 results in the
uppermost age limit for R6 of ~9.46 Ma, which is still within C4Ar.2r
(Fig. 13).
Option 2 assumes that R5 is not a chron but an anomaly; both N5
and N6 correlate to the C5n.1n, and R6 correlates to C4Ar.3r. Such
correlation implies a decrease of sedimentation rates from 0.06 to 0.04
m/kyr, contradicting the observed sedimentological transition towards
higher energy depositional settings. Option 2 also results at the
Bessarabian-Khersonian boundary age of 9.9 Ma. For calculation of the
R6 upper age limit, extrapolation of sedimentation rates from R4 (lith-
ologically similar to R6) results in an age of ~9.6 Ma, meaning, that
there must be a missing C4Ar.2n normal chron, somewhere between
101.4 and 112.5 m. Overall, both correlation options indicate an age of
the Bessarabian-Khersonian boundary at ~9.9 Ma, but option 1 better
agrees with the lithological changes and provides more logical ages for
the R6 zone.
The Bessarabian-Khersonian boundary was also magnetostrati-
graphically dated in the Panagiya outcrop (Russia, Black Sea Basin) at
9.6 Ma, corresponding to the lower part of C4Ar.2r chron (Palcu et al.,
2021). However, the lack of diagnostic fauna in the large parts of layers
14 and 15 in Panagiya (Popov et al., 2016) creates an additional un-
certainty of at least 200 ky (9.75–9.55 Ma). Moreover, the biostrati-
graphic, palaeomagnetic and sedimentological data in Panagiya were
collected sequentially, which could potentially contribute to the
boundary position discrepancy.
The polarity patterns of the upper Khersonian (112.5–120 m) be-
tween N7 and N8 do not t into subsequent GPTS patterns (Fig. 13). A
simultaneous sharp change in both the magnetic polarity and the
depositional environments at the SI6/SI7 transition (lower-upper
Khersonian) points to the presence of a hiatus.
Considering the biostratigraphic data from the upper Kherso-
nian–lower Maeotian of the Karagiye section, the polarity zones N7 – R9
can be correlated to the GPTS in the following order: N7 to C4n.2n, R7 to
C4n.1r, N8 to C4n.1n, R8 to C3Br.3r, N9 to C3Br.2n, R9 to C3Br.2r
(Fig. 13). Calculating sedimentation rates from complete chrons C4n.1r
– C3Br.2n (R7-N9) results in an average rate of 2.55 cm/ky. Using these
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
32
rates, the age of the last Khersonian molluscs in Karagiye section at
117.5 m can be estimated at ~7.8 Ma, while the appearance of the rst
Maeotian ostracods at 122.1 m is around 7.5 Ma. Therefore, with a time
window of 300 kyr between the last Khersonian and rst Maeotian
faunas, a rm placement of the boundary between these two stages in
Karagiye section is complicated.
In other parts of the Eastern Paratethys, such as the Dacian (Lazarev
et al., 2020; Palcu et al., 2019) and the Euxinian basins (Palcu et al.,
2021) the Khersonian-Maeotian boundary was dated at 7.65 Ma,
correlating to the C4n.1n – C4n.1r boundary. Geochronologically, the
7.65 Ma level correlates to 120 m, where the depositional record dis-
plays a small transgression event marked by the disappearance of
coarse-grained sandstones with reworked bindstone fragments and be-
comes dominated by wave-ripple cross-laminated mudstones. We
tentatively place the Khersonian – Maeotian boundary at that level.
5.4.2. Khersonian ecological crisis
The Khersonian faunal assemblage of Karagiye is remarkably poor
and contains only Chersonimatra balcica, Ch. caspia and Ch. bulgarica
molluscs and rare ostracods of the genera Xestoleberis, Callistocythere,
Euxinocythere, Heterocypris and Loxoconcha. Overall, compared to the
Bessarabian, the biodiversity of Khersonian molluscs shrunk from 17
taxa to 3 (with complete turnover) and ostracods from 19 to 7 taxa.
Neither foraminifers nor nannoplankton and marine vertebrates (except
for one sample with a few sh remains) were found. This extensive in-
terval of ecological turnover, called here the Khersonian Ecological
Crisis, was also observed in other parts of the Eastern Paratethys.
In the Terek-Caspian Depression, the Khersonian fauna is mainly
represented by Chersonimactra molluscs and rare freshwater genera such
as Unio, Melanopsis and Viviparus. In the Kura Basin, besides those
molluscs, Khersonian deposits occasionally comprise Solen subfragilis
molluscs, Cyprideis littoralis ostracods and rare Ammonia beccarii fora-
minifers. Two latter taxa may indicate a slightly higher salinity than in
Karagiye and Terek-Caspian Depression. The Khersonian fauna of the
Euxinian Basin is more diverse than in the Caspian. On the Taman
Peninsula, it includes the molluscs Chersonimactra and foraminifers
Ammonia (Muratov and Nevesskaya, 1986). In the Dacian Basin, the
Khersonian interval is characterised by molluscs Chersonimactra, Coe-
logonia and Potamides, rare foraminifers Ammonia and frequent ostra-
cods Cyprideis torosa (Palcu et al., 2019; Lazarev et al., 2020).
The comparison of faunal records across the Eastern Paratethys
shows a heavy impact of the Khersonian Ecological Crisis on the biotic
record. Besides the catastrophic decline of invertebrate communities,
the fossil record lost nearly all large marine faunas such as whales,
dolphins and seals. The exact driver(s) of this process remain nebulous.
The lack of foraminifers in the Caspian Basin (except for some rare
Ammonia) suggests that the salinity of the basin dropped below 9‰.
Overall, the faunal-based salinity of the Eastern Paratethys during the
Khersonian was estimated between 5 and 12‰ (Paramonova, 1994), but
requires further fauna-independent conrmation.
5.4.3. Khersonian-Maeotian palaeoenvironmental evolution
During the Khersonian, the Eastern Paratethys started experiencing
extreme water level uctuations with suggested amplitudes of up to 300
m (Popov et al., 2010), which were linked to the climatically driven
disruption of the water budget. During the lowstand episodes, some
parts (basins/subbasins) disconnected, exposing large areas of the
former shelf. In the Euxinian Basin, three extreme lowstand events were
recognised from seismic proles: one large event spanning the
Bessarabian-Khersonian transition, one minor event in the middle of the
Khersonian and the strongest one in the terminal Khersonian (Popov
et al. 2010, 2022).
The expression and timing of these events in the Caspian Sea remain
blank. During the Khersonian, the Caspian Sea retreated from the vast
areas of the Ustyurt Plateau of Central Asia (Paramonova, 1994).
Moreover, the rst Khersonian water drop at the
Bessarabian-Khersonian transition along with the tectonic pulse in the
Caucasus caused a closure of the Transcaucasian Strait (Popov et al.
2010, 2022). As a result, the sea retreated from the upper Kura Basin
(Kartli Depression) (Buleyshvili, 1960) making the Caspian Basin con-
nected to the rest of the Eastern Paratethys only via the northern
Pre-Caucasus Strait (Scythian Shelf – Caspian-Terek Depression) (Popov,
2004).
The observations on the lithofacies in Karagiye suggest that during
the Khersonian, also the Caspian Basin experienced some water-level
uctuation. In the late Bessarabian, the carbonate platform was gradu-
ally shallowing upwards and later, with erosional contacts, became
covered with Khersonian barrier rudstones. Such reorganisation may be
linked with the end-Bessarabian water level fall, which quickly
rebounded with the Khersonian transgression. As this event appears
within the 47-kyr-long C5n.1n chron, this process was rather rapid and
should not have caused much loss of the depositional record. Hence, the
Bessarabian-Khersonian transition in the Caspian Basin was not as dra-
matic as in the Euxinian Basin, potentially because the major water level
drop in the Caspian Basin happened earlier, at the early-late Bessarabian
boundary (65 m, 10.67 Ma) where the facies change seems to be more
severe.
Between 9.87 and 9.48 Ma (SI6, 93.2–112.5 m), the Karagiye record
demonstrates a gradual progradation from a carbonate platform barrier
to a lagoon and further to a backshore with palaeosols. Higher up, the
depositional record comprises a 1.5-Myr-long hiatus (between 9.5 and
8.0 Ma) that, in our opinion, characterises a strong water level drop.
Future focus on geochronological, sedimentological and seismic con-
straints from the deep-water parts of the basin is needed to verify this.
With the return of aquatic environments at ~8.0 Ma (112.5 m),
Karagiye turned into a tidal plain with frequent Chersonimactra molluscs
and microbial mats. At ~7.8 Ma, prior to the Khersonian–Maeotian
boundary, the last Khersonian fauna disappeared, characterising the
culmination of the Khersonian Ecological Crisis. A similar faunal trend
identied as the “Barren Zone” (Paramonova, 1994; Kojumdgieva et al.,
1989), was previously documented in the Euxinian and Dacian basins
and was linked to the effect of the nal and strongest Khersonian water
level drop (Lazarev et al., 2020; Palcu et al., 2019).
The Khersonian lowstand was terminated by a large Maeotian
transgression at 7.65 Ma dated in the Euxinian and the Dacian basins
(Palcu et al. 2019, 2021; Lazarev et al., 2020). The appearance of new
invertebrates of Mediterranean afnity (Popov et al., 2022) and the rise
of the
87
Sr/
86
Sr isotopic ratio towards the oceanic values (Vasiliev et al.,
2021) may suggest a short reconnection of the Eastern Paratethys with
the global ocean.
In Karagiye, the Maeotian transgression was accompanied by neither
faunistic nor remarkable depositional changes. At 7.65 Ma (120 m), the
late Khersonian inter-to-supratidal environments became slightly
deeper – sub-to intertidal and contained no fauna. Only at 7.5 Ma, the
rst characteristic Maeotian ostracod and mollusc assemblage appeared
in the record. The delayed occurrence of Maeotian molluscs in the
Caspian Basin could be linked with a slightly delayed reconnection be-
tween the Caspian and the Euxinian Basins.
At around 7.3 Ma, the depositional settings in Karagiye changed
towards the shallow water carbonate platform interior with widespread
oolithic barriers and microbial mats.
The comparison of the extreme Khersonian water level oscillation of
the Euxinian Basin with the facies and faunal trends in Karagiye suggests
that the Caspian Basin had its own hydrological evolution, which does
not correlate with the Euxinian Basin. The Bessarabian-Khersonian and
terminal Khersonian water level drops did not greatly impact the
depositional system of Karagiye. Instead, the early-late Bessarabian
(10.67 Ma) and the middle Khersonian (between ~9.5 and ~8 Ma) re-
gressions had the strongest effect on the basin.
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
33
5.5. “Marine” vertebrate fauna
Though most of the vertebrate remains come from ex-situ nds, the
tentative reconstruction of the fauna allowed the following conclusions.
The Konkian stage was richer in sh diversity in comparison to younger
sediments and included fully marine organisms such as sharks, perci-
forms and otolith-based large-sized sciaenids (Fig. 14). Among the latter,
the small-sized form represents a new, undescribed sciaenid species,
whereas the large-sized form can be assigned to the genus Trewaschiaena
(Bannikov et al., 2018). The latter represents the oldest representative of
the genus and, at the same time, counts as the second Konkian species of
the genus in the Eastern Paratethys.
The marine mammal fauna of Karagiye is rather diverse, with at least
ve in-situ taxa and a few additional ex-situ taxa (Otradnocetus virodovi,
Praepusa, Kentridon fuchsii, etc.). Among them, the baleen whales Imer-
ocetus and Otradnocetus were previously documented from the
Karaganian-Konkian (without precise dating) of other parts of the
Eastern Paratethys (south-western (Mchedlidze, 1964) and
north-western Caucasus (Gol’din, 2018; Mchedlidze, 1984). The Kar-
agiye record extends the palaeogeographic distribution of the genera,
further for the Otradnocetus with much longer probable Volhynian
stratigraphic occurrence.
A partial skeleton of Pachyacanthus was found in the Konkian sedi-
ment debris, making its stratigraphic position uncertain. A second par-
tial skeleton, with a similar body size and similar fossilisation state
(bone colour and appearance), has been found on the Volhynian beds
(ex-situ), suggesting that the Konkian (ex-situ) nd should also be
considered Volhynian. The Karagiye record, which indicates a Volhy-
nian age, has the same age as the Central Paratethyan record, suggesting
that this toothed whale had a basin-wide (Paratethyan) distribution.
Interestingly, some of Karagiye’s marine mammalian taxa have ages
similar to the Atlantic Ocean record. Herpetocetinae indet. found from
Volhynian debris (dated younger than 12.4 Ma) shares characters
similar to Herpetocetus and Metopocetus. The oldest Metopocetus is known
from the Nomini Cliffs, USA, which was dated 14–13.5 Ma (Kodama and
Pazzaglia, 2023). In general, Herpetocetinae becomed widespread
worldwide since the Late Miocene (Boessenecker, 2011). The most
probable scenario that explains the Paratethyan and out-of-Paratethyan
occurrences of Herpetocetinae would be that the faunal exchanges
occurred between the Paratethys and the global ocean before the
isolation and afterwards the fauna radiated in the isolated Eastern Par-
atethyan Basin. Previously, the Paratethys has already been suggested as
a diversication hotspot of whales, as it has been demonstrated by
Gol’din (2018) on the example of Cetotheriidae and some clades of
Phocinae (Koretsky, 2001). Further ndings in and outside Paratethys,
as well as a comparison with another faunistic record, will be necessary
to reconstruct the basin’s role in the biotic record’s palaeobiogeographic
history.
The Bessarabian fauna replaced the Konkian and Volhynian with an
assemblage including sparids, a small-sized gobiid, a perciform taxon
and a large-sized scombrid. A similar association could be found also in
the Sarmatian of the Vienna Basin, Central Paratethys (DV personal
observations). A marine mammal fauna includes Paratethyan endemic
taxa, widely distributed across the Eastern Paratethys. The lack of any
vertebrates in the Khersonian and Maeotian beds suggests that this part
of the region was not favourable for their life.
6. Conclusion
Using the integrated stratigraphic approach, we have created well-
dated and almost complete palaeoenvironmental and biotic records of
the Karagiye section, which provide insight into the evolution of the
Caspian Basin before (Konkian), during (Volhynian—Khersonian) and
after (Maeotian) the major endorheic phase of the Eastern Paratethys.
Before the major endorheic phase, during the present portion of
lower Konkian (Kartvelian), the Karagiye area was an open lagoon with
very low faunal diversity. During this period, the Eastern Paratethys had
a restricted or closed connection to the global ocean; and the Caspian
Basin was fresher than the Euxinian Basin, with salinity ranging within
the polyhaline values. Later, the appearance of the numerous middle
Konkian marine faunal assemblages marked the restoration of connec-
tivity with the global ocean via the Central Paratethys and the estab-
lishment of normal marine environments in the Caspian Basin.
The geological record of the Konkian–Volhynian boundary is missing
in Karagiye, hampering the expression of the Paratethyan isolation at
12.65 Ma. After the marine connectivity cut off at 12.65 Ma, the Caspian
faunal record underwent a remarkable biotic turnover. Through the
preserved portion of the Volhynian (12.33–12.0 Ma), the Karagiye was a
shallow-water marginal lagoon inhabited by new endemics, including a
few taxa inherited from the Konkian.
At 12.0 Ma, the large Bessarabian transgression established a rela-
tively deep-water offshore environment and introduced new faunas. At
~10.7 Ma, the sudden progradation of shallow water carbonate plat-
form followed by new molluscs and foraminifers indicate the late Bes-
sarabian time. Across the Eastern Paratethys, this event, named here the
intra-Bessarabian Carbonate Surge, is characterised by a remarkable
increase of carbonate precipitation that was potentially caused by a
tectonically driven increase of erosion on land with further supply into a
landlocked Eastern Paratethys. Widespread oolite formation and
hypercalcication of microfauna suggest high anomalohaline salinity at
that time.
In the terminal Bessarabian, the sea retreated from Karagiye but
briey returned with a small-scale Khersonian transgression at 9.9 Ma
that established here the marginal carbonate platform barrier with new
highly impoverished fauna. Compared to the Bessarabian, the Kherso-
nian fossil record shows no foraminifers, most of the ostracods and all
marine vertebrate mammals and the biodiversity of molluscs shrunk to a
single genus. This event, called here the Khersonian Ecological Crisis
(KEC), was probably linked to strong salinity changes.
The gradual early Khersonian shallowing in Karagiye culminated in
palaeosol formation at ~9.5 Ma, which was followed by a 1.5-My-long
hiatus (until ~8.0 Ma) that was linked to one of the extreme Kherso-
nian lowstands of the Caspian Basin. In the late Khersonian over the
hiatus, the Karagiye represented a shallow-water tidal plain. At around
7.8 Ma, the Khersonian fauna disappeared in Karagiye, marking the peak
of the KEC. This event was potentially linked to the freshening and
disconnection of the Caspian Basin from the Euxinian Basin, which at
that time experienced the terminal Khersonian water level drop.
At 7.65 Ma, a small-scale transgression in Karagiye tentatively marks
the Khersonian–Maeotian boundary. However, the rst Maeotian faunas
appeared here only at 7.5 Ma, which was likely caused by a delayed
reconnection with the Euxinian Basin.
Our study shows that while being a part of the Eastern Paratethys,
the Caspian Basin still had its unique palaeohydrological evolution.
During the isolation phase of the Eastern Paratethys, the Caspian Basin
faunal record followed a similar trend with high diversication during
the Volhynian-Bessarabian to a near-total faunal extinction during the
Khersonian. However, the facies trend of Karagiye shows a signicant
difference in the number and amplitude of extreme Khersonian water
level uctuations compared to the neighbouring Euxinian Basin and,
thus, requires an in-depth sedimentological analysis.
Integrating high-resolution dating with documentation of biotic re-
cords creates an important framework for more precise intra-basinal
biostratigraphic correlations. It is especially crucial for the dating of
the marginal Paratethyan outcrops that, along with marine faunas, often
contain land mammals whose dating can be challenging. However,
further work on the dating and distribution of biozones across the
Eastern Paratethys is highly encouraged.
CRediT authorship contribution statement
Sergei Lazarev: Writing – review & editing, Writing – original draft,
S. Lazarev et al.
Marine and Petroleum Geology 173 (2025) 107288
34
Methodology, Investigation, Formal analysis, Data curation, Conceptu-
alization. Oleg Mandic: Methodology, Investigation, Formal analysis.
Marius Stoica: Methodology, Investigation, Formal analysis, Data
curation. Pavel Gol’din: Methodology, Formal analysis, Data curation.
Stjepan ´
Cori´
c: Methodology, Formal analysis, Data curation. Mathias
Harzhauser: Writing – review & editing, Formal analysis, Data cura-
tion. Wout Krijgsman: Writing – review & editing, Data curation. Dias
Kadirbek: Writing – review & editing, Formal analysis. Davit Vasilyan:
Writing – review & editing, Writing – original draft, Supervision, Project
administration, Methodology, Funding acquisition, Formal analysis,
Data curation.
Declaration of competing interest
The authors declare that they have no known competing nancial
interests or personal relationships that could have appeared to inuence
the work reported in this paper.
Acknowledgements
Our study is dedicated to the memory of our friend and colleague
Professor Laurent Richard, Nazarbayev University, who enthusiastically
supported us and the project from the beginning of the joint research.
We want to thank: Sergey Popov for valuable discussions on different
aspects of the Paratethys research; Milovan Fustic for the support in the
organisation of the eldwork and fruitful discussions on the depositional
history of the Paratethys; Renaud Roch for valuable assistance in the
fossil excavation in the eld and fossil preparation in the lab; Bettina
Reichenbacher and Werner Schwarzhans for the guidance in the iden-
tication of the otolith material; Pavlo Otriazhyi for the help with the
organisation and identication of the fossil record of the Karagiye; Mark
Dekkers for guidance in IRM measurements; our driver Vadik Gassiev for
our safe and smooth steppe rides, patience and all logistic support which
made our ambitious eld campaigns possible. We are grateful to all
geology students of the Nazarbaev University who contributed from
2019 to 2024 to the study of the geology and fossil record of the Kar-
agiye section. Special thanks to two anonymous reviewers whose com-
ments helped to improve the manuscript. The study has been funded by
the Swiss National Science Foundation project # 200021_197323 and a
seed funding grant from the University of Geneva SFG 772 (to DV).
Appendix A. Supplementary data
Supplementary data to this article can be found online at https://doi.
org/10.1016/j.marpetgeo.2025.107288.
Data availability
All data associated with this manuscript is available as Supplemen-
tary materials.
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