2018 | 71/3 | 135 – 146 | 9 Figs. | www.geologia-croatica.hr Journal of the Croatian Geological Survey and the Croatian Geological Society 1. INTRODUCTION The Konkian is the Middle Miocene stage of the Eastern Parate- thys that corresponds to the NN6-NN7 Nannoplankton Zone (NEVESSKAYA et al., 2005), to the Serravallian of the Global Time Scale and to the upper Badenian (Kosovian) of the Central Paratethys (HILGEN et al., 2012). The Karaganian/Konkian boundary is dated at 13.4 Ma, and the Konkian/Sarmatian boun- dary is dated at 12.65 Ma (PALCU et al., 2017). The Konkian (upper Badenian) time is characterized by a marine transgression which reactivated connections between the Central and Eastern Parate- thys. The preceding Karaganian time was characterized by euryha- line conditions which correspond to the Badenian Salinity Crisis in the middle Badenian of Central Paratethys (e.g. MURATOV & NE- VESSKAYA, eds., 1986; PERYT, 2006). After the Konkian (up per Badenian), the Sarmatian basin was characterized by palaeoenviron- men tal changes and the appearance of an endemic fauna in the Eastern and Central Paratethys. (e.g. MURATOV & NEVESSKA- YA, eds., 1986; NEVESSKAYA et al., 2005; HILGEN et al., 2012). The aim of this study is to understand how the foraminiferal assemblages developed and to show the differences between the shallow-water and deeper water basins in the Konkian. The re- sults are discussed in the context of temporal and spatial changes of foraminiferal species diversity and presented together with the analysis of molluscs as an additional group in the various Konkian facies of the Southern Ukraine. 2. THE KONKIAN REGIONAL STAGE OF THE EASTERN PARATETHYS 2.1. Peculiarities of the Konkian stratigraphy of the Eastern Paratethys The first stratigraphic studies of the Neogene of the Eastern Pa- ratethys were based on identification of mollusc assemblages. If Biostratigraphy of the Konkian (Middle Miocene of the Eastern Paratethys) deposits of Southern Ukraine based on foraminifera Yuliia Vernyhorova National Academy of Sciences of Ukraine, Institute of Geological Sciences, Department of stratigraphy and palaeontology of the Cenozoic deposits, O. Honchar str., 55 b, Kyiv, 01601 Ukraine; (july.vern@gmail.com) doi: 10.4154/gc.2018.18 Abstract The Konkian (Middle Miocene) foraminiferal assemblages and molluscs from five Wells situated in Southern Ukraine were studied in order to correlate the palaeoecology and biostratigraphy of the coeval palaeobasins with different environmental conditions. The article contains compre- hensive analysis of controversial issues of the Konkian stratigraphy of the Eastern Paratethys and additional keys for determination of Konkian development phases by foraminifera and mol- luscs. Five stenohaline normal-marine, two euryhaline and one mixed foraminiferal assemblage were identified in different levels in the investigated wells with the analysis of their accordance to different molluscs assemblages. The study defines an isochronous foraminiferal assemblage for some wells, suggests a palaeoecological and stratigraphic reconstuction of the middle Mio- cene sediments in the Eastern Black Sea Region and recognizes two models of development of the Konkian foraminiferal assemblages. These models show the differences between envi- ronmental conditions in the shallow-water basin of the Eastern Black Sea Region and deeper water basin of the Kerch Peninsula at that time. While the Eastern Black Sea Region was influ- enced by frequent and abrupt changes in environmental conditions during almost all Konkian time, a relatively deeper basin of the Kerch Peninsula had a successive phase. The late Konkian time created similar depositional conditions for both basins. certain species of mollusсs were traced in sections, then these deposits were defined as the same age and such mollusc associa- tions were identified as “Beds with molluscs” (e.g. ANDRUSOV, 1917; ARKHANGUELSKY, 1930). Several “Beds with mol- luscs” were determined in the Konkian deposits: Beds with Ve­ nus konkensis in the Northern Black Sea Region of the Southern Ukraine (SOKOLOW, 1899), were named later as the Veselyanka Beds by MERKLIN (1953); the Pholadidae Beds on the Kerch Peninsula of the Southern Ukraine (ANDRUSOV, 1917); the Kartvel Beds in Georgia (DAVITASHVILY, 1930); the Sartagan Beds in Transcaspian (ZHIZHCHENKO, 1937a, b). The Kartvel Beds are characterized (Fig. 1) by Pholadidae (Barnea pseu­ doustjurtensis BOGATCHEV, B. ustjurtensis (EICHWALD), B. kubanica (ZHIZHCHENKO) B. scrinia (BOGATSCHEV) etc.); the Sartagan Beds are defined as deposits with a rich marine stenohaline Konkian mollusc fauna; the Veselyanka Beds are de- fined as deposits with euryhaline Konkian molluscs (MERKLIN, 1953; VERESHAGIN & MIRONOVA, 1982; MURATOV & NEVESSKAYA, eds., 1986). Later, such Beds with molluscs were found in the Konkian of other areas of the Eastern Parate- thys (e.g. VARENTSOV, 1950; MERKLIN, 1953; MURATOV & NEVESSKAYA, eds., 1986). Shallow-water Konkian deposits often comprise Beds with Ervilia trigonula SOKOLOV or Beds with E. trigonula and Barnea pseudoustjurtensis, B. kubanica in the Southern Ukraine (MOLYAVKO, 1960; BARG, 1969). There- fore, they were called the “Ervilia-Pholadidae Beds” and were also considered as Kartvel Beds (BARG, 1969). The age of the Kartvel Beds has been under discussion. These Beds were defined as belonging to both the Karaganian and the Konkian regiostages based on the mollusc species com- position (Pholadidae) (ZHIZHCHENKO, 1937a, 1937b; BU- RIAK, 1965). They were also considered as the final stage of the Karaganian (SUDO, 1961; NEVESSKAYA et al., 2005) or were Article history: Manuscript received January 30, 2018 Revised manuscript accepted September 18, 2018 Available online October 24, 2018 Keywords: Foraminifera, Mollusca, Biostratigraphy, Palaeocology, Konkian, Upper Badenian, Eastern Paratethys, Southern Ukraine G eo lo gi a C ro at ic a Geologia Croatica 71/3136 determined as the individual Kartvelian regiostage (ZHGENTI, 1976; ILYINA, 2000; ZHGENTI & MAISSURADZE, 2016). The presence of typical Konkian species of foraminifera (Varidentella reussi sartaganica KRASHENINNIKOV, Nodo­ baculariella konkensis BOGDANOWICZ, Nonion tauricus KRASHENINNIKOV, Reussella spinulosa (REUSS), Cassi­ dulina bulbiformis KRASHENINNIKOV, Discorbis kartvelicus KRASHENINNIKOV, D. supinus KRASHENINNIKOV etc.) and ostracods (Leptocythere distenta SCHNEIDER, Loxoconcha spongiosa LJULJEV, Trachyleberis lascarevi SCHNEIDER etc.) in the Kartvel Beds is a sufficient basis to determine them as the Konkian regiostage (Fig. 1) (KRASHENINNIKOV, 1959; BARG & IVANOVA, 2000; KRASHENINNIKOV et al., 2003; BARG & STEPANIAK, 2003; BONDAR, 2004; PRISYAZHNYUK et al., 2007; GOLOVINA et al., 2009; VERNIGOROVA, 2009; IVANOVA, 2012; VERNYHOROVA, 2014, 2015a, b, 2016). The Konkian age of the Sartagan Beds, was confirmed not only on the basis of molluscs but also by normal-marine assem- blages of Konkian foraminifera (Fig. 1) such as Quinqueloculina minakovae ukrainica DIDKOWSKI, Varidentella reussi sartaga nica, Nodobaculariella konkensis, N. didkowskii BOGDANOWICZ, Articulina vermicularis BOGDANOWICZ, Melonis soldanii (ORBIGNY), Borelis melo (FICHTEL & MOLL), Cassidulina bulbiformis, Discorbis kartvelicus, D. supinus, Reussella spinu­ losa, etc. (KRASHENINNIKOV, 1959; DIDKOVSKIY, 1959; DJANELIDZE, 1970) and the Konkian ostracods such as Trachyl­ eberis semiornara LJULJEV, T. golubjatnikovi SCHNEIDER, T. lascarevi, Leptocythere distenta, Loxoconcha spongiosa, Aglaio­ cypris konkensis SCHNEIDER, Aurila similis (REUSS) etc. (BARG & STEPANIAK, 2003; BONDAR, 2004; PRISYAZHNYUK et al., 2007). The Konkian age of the Veselyanka Beds, except for mol- luscs, is also confirmed by euryhaline assemblages of Konkian foraminifera (Fig. 1) such as Nonion tauricus KRASHENIN- NIKOV, Elphidium farsiensis KRASHENINNIKOV, E. horri­ dum BOGDANOWICZ, etc. (KRASHENINNIKOV, 1959; DID- KOVSKIY, 1959; DJANELIDZE, 1970) and the Konkian ostracods (BARG & STEPANIAK, 2003; BONDAR, 2004; PRISYAZHNYUK et al., 2007). According to the recent research on the Konkian/Sarmatian boundary in Georgia, the Sarmatian age was suggested for the Veselianka Beds. This conclusion was drawn from a comparison of foraminiferal assemblages from the Veselianka Beds with those from the Sartagan Beds and the lower Sarmatian deposits (KOIAVA et al., 2016). However, these fo- raminiferal data were not consistent with other palaeontological data (e.g. molluscs, ostracods) from the Konkian deposits which suggested a Konkian age for the Veselianka Beds (e.g. MERK- LIN, 1953; MURATOV & NEVESSKAYA, eds., 1986). The Konkian regiostage was subdivided into three substages: Kartvel Beds, Sartagan Beds and Veselyanka Beds by MERK- LIN (1953). However, there are researchers who do not support Merklin’s point of view since the Konkian sections in different areas of the Eastern Paratethys have different and irregular de- posit patterns with various “Beds with molluscs” (VARENTSOV, 1950; BULEISHVILI, 1960; NOSOVSKIY, 1960; CHIKOVANI, 1964; BARG, 1969; 2008; PRISYAZHNYUK et al., 2007; VERNIGOROVA, 2008, 2009, 2012). Also, some sections may have several levels with the same type of fossiliferous beds, while in others some horizons of such beds are missing (review pre- sented in VERNIGOROVA, 2009). In addition, the Konkian de- posits in Southern Ukraine comprise molluscs or foraminiferal assemblages with both normal-marine and euryhaline species (DIDKOVSKIY, 1959; MOLYAVKO, 1960; BARG, 1969; VERNIGOROVA, 2012). As a result, researchers have two different opinions on the Konkian stratigraphy (Fig. 2). The first group considers that the Kartvel Beds, the Sartagan Beds and the Veselyanka Beds rep- resent development phases in the Konkian basin (MERKLIN, 1953; BARG, 1993; BARG & STEPANIAK, 2003; IVANOVA, 2012; STARIN, 2012; KOIAVA et al., 2016). They are therefore used in regional stratigraphy as the Konkian substages. The se- cond group thinks that these beds can be associated with different environmental conditions which could appear at different times during the Konkian. So they are used as additional biostrati- graphic subdivisions such as “Beds with fauna” (according to ZHAMOIDA, ed., 1977; TESLENKO, ed., 1997; GOZHYK, ed., 2012) in the local stratigraphy for the correlation of sections and palaeoenvironmental reconstructions of separate areas (VAR- ENTSOV, 1950; BULEISHVILI, 1960; CHIKOVANI, 1964; BURIAK, 1965; PRISYAZHNYUK et al., 2007; VERNY- HOROVA, 2014, 2015a, b, 2016). Thus, today the terms the Kartvel Beds, the Sartagan Beds and the Veselyanka Beds are not clearly defined, as they can refer to stratigraphic horizons or palaeoecological conditions. So, there are problems in the case of their use for the correlation when it is necessary to compare deposits with the same names but they can have different semantic meanings. Therefore, it is possible to agree with the proposal of ILYINA (2000) not to divide the Konkian stage into several substages and not to call these units by their own names such as the Kartvel Beds, the Sartagan Beds and the Veselyanka Beds. However in the case when a researcher decides to divide the Konkian into substages it is proposed to use the terms: lower, middle and upper Konkian substages. If a re- Barnea pseudoustjurtensis, B. ustjurtensis, B. kubanica, Ervilia trigonula Konkian characteristic species; but there aren't specific and characteristic species for identification just these beds. There are several assemblages with different paleoecological characteristics Konkian characteristic species; predominance of stenohaline species of genera: Lagena, Nodobaculariella, Spirolina, Globulina, Virgulina, Reussella, Pyrgo, etc. Konkian characteristic species; predominance of stenohaline species of genera: Chama, Chlamys, Anadara, Turreitella, Spiratella etc. Konkian characteristic species; predominance of euryhaline species of genera: Elphidium, Nonion, Ammonia. Presence of a small number of normal-marine species of genera: Bulimina, Cassidulina, Quinqueloculina etc. is possible Konkian characteristic species; predominance of euryhaline species of genera: Parvivenus, Alvenius, Parvicardium, Sandbergeria etc. Veselyanka BedsKartvel Beds Mollusca Foraminifera Sartagan Beds Figure 1. Typical species of molluscs and foraminifera from the Konkian of the Eastern Parethetys (according to ZHIZHCHENKO, 1937a, b; MERKLIN, 1953; KRASH­ ENINNIKOV, 1959; BARG, 1969; IVANOVA, 2012, etc.). G eologia C roatica Vernyhorova Yuliia: Biostratigraphy of the Konkian (Middle Miocene of the Eastern Paratethys) deposits of Southern Ukraine based on foraminifera 137 searcher still decides to use individual names for these substages then it is proposed not to call them as Beds, but rather the Kart- velian substage, the Sartaganian substage and the Veselyankian substage (e.g. MAISSURADZE et al., 2014; PALCU et al., 2017). In addition, since the initial criteria for recognition of the Konkian substages were not universal, it is necessary to clarify the defini- tions for each of these substages by adding criteria to aid more accurate recognition of them in sections. At the same time, it is necessary to take into account the fact that the different facies of the Konkian deposits in the Eastern Paratethys generally contain stable species assemblages of fauna with certain palaeoecologi- cal characteristics that are separate biostratigraphic subdivisions “Beds with the fauna” (according to ZHAMOIDA, ed., 1977; TESLENKO, ed., 1997; GOZHYK, ed., 2012). In this case, it has been proposed to not call these subdivisions names such as the Kartvel Beds, the Sartagan Beds, the Veselianka Beds, but to name them after the characteristic fossils (e.g. limestones with Ervilia trigonula, Barnea pseudoustjurtensis) (VERNY- HOROVA, 2014, 2015a,b, 2016). 2.2. Criteria for determination of the initial (early) and final (late) development stages of the Konkian basin by molluscs and foraminifera Since the different Beds with fauna may occur at different strati- graphic levels of the Konkian of the Eastern Paratethys they are not unique for particular development phases of the Konkian ba- sin. Therefore, additional criteria for determination of the deve- lopment stages of the Konkian basin are needed. Experience in the study of foraminifera and molluscs in the Konkian deposits from different areas of the Southern Ukraine, the Ciscaucasus and the Mangyshlak Peninsula (VERNIGOROVA et al., 2006, 2009; VERNIGOROVA, 2008, 2009, 2012; GOLOVINA et al., 2009; BRATISHKO et al., 2015) allows the definition of addi- tional criteria for determination of the initial (early) and final (late) development stages of the Konkian basin (VERNY- HOROVA, 2015a; POPOV et al., 2016). An initial stage of the Konkian basin development may be recognized by a specific foraminiferal assemblage with a pre- dominance of the genera Cassidulina and Discorbis (Cassidulina bulbiformis, C. bogdanowiczi KONENKOVA, Discorbis kartve­ licus etc.) (Fig. 3). This regular trend can be observed in some relatively deep Konkian deposits (clays and marls) of the eastern part of the Crimean Peninsula, the Kerch Peninsula and the Cis- caucasus (KRASHENINNIKOV, 1959; BOGDANOWICZ, 1965; VERNYHOROVA, 2015a; POPOV et al., 2016; PALCU et al., 2017). This stage is clearly visible only in the most complete Konkian sections. Otherwise the stage is difficult to identify, be- cause similar foraminiferal assemblages are present in different Konkian stratigraphic horizons, especially in the shallow-water deposits (VERNYHOROVA 2014, 2015a, b, 2016). Criteria for determining of the initial (early) development phase of the Konkian by molluscs are also not yet clearly defined. The early Konkian may contain Beds with Ervilia and Pholadidae. How- ever, as has been indicated above, they are also present in other stratigraphic horizons. The final development phase of the Konkian basin can be defined more precisely. These sediments comprise not only eu- ryhaline species of molluscs and foraminifera which are typical for the Konkian basin but also a small amount of early Sarmatian species (e.g. molluscs – Obsoletiforma lithopodolica ruthenica (HILBER), Ervilia dissita dissita (EICHWALD) small-sized tests; foraminifera – Elphidium horridum, Porosononion mart­ Konkian Veselyankian (Veselyanka Beds) Sartaganian (Sartagan Beds) Kartvelian (Kartvel Beds) Beds with Lutetia (Spaniodontella) gentilis – Research interval ? Karaganian Sarmatian Sarmatian deposits Sarmatian depositsSarmatian Se rra va llia n Ba de ni an Sy st em N e o g e n e M i o c e n e M i d d l e Se rie s Su b- se rie s St ag e Nothern Black Sea Region Crimea Peninsula Kerch Peninsula Eastern Paratethys Regional stage Central Paratethys Stage Veselyanka Beds Representations about the stratigraphic value of “beds with fauna”GTS, 2004 "Beds with molluscs" are reflection regional substages of the Konkian "Beds with molluscs" are biostratigraphic units that are traced on different levels in coeval facies Sartagan beds West Centre East Kartvel beds Veselyanka beds Veselyanka beds Sartagan Beds Kartvel Beds Kartvel beds Beds with Lutetia (Spaniodontella) gentilis Nothern Black Sea Region Crimea Peninsula Kerch Peninsula "beds with molluscs" are not recognized in sections Figure 2. The different understanding of stratigraphic value of the Kartvel Beds, Sartagan Beds and Veselyanka Beds in the Southern Ukraine deposits in strati­ graphic schemes of the Konkian of the Eastern Paratethys. ? Predominance of Konkian euryhaline species and presence of a small number of the early Sarmatian species (e.g. E. dissita dissita, Obsoletiforma lithopodolica ruthenica; their shells have small sizes) A variety of molluscs and foraminiferal Konkian assemblages that have different paleoecological characteristics. It is depend on environmental conditions in different areas of the Konkian basin especially in shallow-water deposits. Predominance of Konkian euryhaline species and presence of a small number of the early Sarmatian species (e.g. E. horridum, Porosononion martkobi, Nonion bogdanowichi ) Konkian characteristic species; reduced species composition of assemblages; normal-marine species; predominance of the genera Cassidulina and Discorbis (e.g. C. bulbiformis, C. bogdanowiczi, D. kartvelicus) MolluscsPhase of development late middle early Ko nk ia n R eg io - st ag e Foraminifera Figure 3. Characteristics of the Konkian development phases based on foraminifera and molluscs (VERNYHOROVA, 2015a). G eo lo gi a C ro at ic a Geologia Croatica 71/3138 kobi (BOGDANOWICZ), Nonion bogdanowiczi VOLOSHI- NOVA). This regular trend can be observed in the Konkian se- diments of the Northern Black Sea Region (including the Konkian stratotype), on the Kerch Peninsula, the Ciscaucasus and the Mangyshlak Peninsula (SOKOLOW, 1899; LIVEROVSKAYA, 1935; 1960; BOGDANOWICZ, 1965; VERNIGOROVA et al., 2009; VERNYHOROVA, 2014; BRATISHKO et al., 2015; PALCU et al., 2017). 3. THE KONKIAN LITHOFACIES OF THE SOUTHERN UKRAINE The Konkian deposits of different lithofacies features are wide- spread in the Southern Ukraine (Figs. 4, 5). Shallow-water de- posits (3-25 m thick) have accumulated in the Northern Black Sea Region and in most parts of the Crimean Peninsula (e.g. MOLY- AVKO, 1960; BARG & STEPANIAK, 2003). Different types of limestones (Hladkivka Formation, Tarkhankut Formation, Me- kenziev Strata) prevail in the western part of the Northern Black Sea Region and in the western and southern parts of the Crimean Peninsula; sands and sandstones (Novokakhovka Formation) are more abundant in the south-east of the Northern Black Sea Re- gion and in the northern and central parts of the Crimean Penin- sula; laminated green-grey clays with varying sandy admixtures (Tymoshivka Formation) occur in the north-eastern part of the Northern Black Sea Region (VERNYHOROVA, 2015b, 2016). The Konkian deposits in these areas have sedimentation hiatuses and these strata are not stratigraphically complete (MOLYAVKO, 1960; DIDKOVSKIY & KULICHENKO, 1975, VERNY- HOROVA, 2015b, 2016). More deep-water deposits (36-155 m thickness) are monoto- nous dark gray clays, partially laminated with rare sandy admix- tures that have accumulated in the Kerch Peninsula and in the south-eastern parts of the Crimean Peninsula. They differ from other Konkian deposits of the Southern Ukraine by their litho- logical peculiarities and occurrence of more deep-water species of fauna (e.g. ANDRUSOV, 1917; OSIPOV, 1927; ARHANGUEL- SKY, 1930; ARKHANGUELSKY, ed., 1940; MOLYAVKO, 1960; BARG & STEPANIAK, 2003; VERNYHOROVA, 2014). These Konkian deposits represent a complete stratigraphic se- quence and all of them are combined in the Petrovske Formation (VERNIGOROVA et al., 2012; VERNYHOROVA, 2014). 4. MATERIALS AND METHODS The Konkian deposits were studied in five wells from several re- gions of the Southern Ukraine (Figs. 4, 6). There are four wells from the Eastern Black Sea Region (upper part of the Tymoshivka Formation): Well 8z (altitude – 69.5 m; thickness of the Konkian deposits – 4.2 m; 26 samples selected); Well 9 (altitude – 69.7 m; thickness of the Konkian deposits – 1.7 m; 24 samples selected); Well 6 (altitude – 30.5 m; thickness of the Konkian deposits – 5.0 m; 33 samples selected); Well 8m (altitude – 86,0 m; thickness of the Konkian deposits – 10.0 m; 47 samples selected) and one Well from the Kerch Peninsula (Petrovske Formation): Well 20 (alti- tude – 17.0 m; thickness of the Konkian deposits – 51.0 m; 82 samples selected). The stratigraphic sequence of these deposits was determined on the basis of foraminiferal and mollusc assem- blages. Mollusc data from Well 8z were defined also by PRISY- AZHNYUK et al., 2007 and were used in this research. During analysis, data on the Konkian foraminiferal and molluscs assem- blages and lithological features of the Konkian deposits from other areas of the Southern Ukraine from published literature (e.g. DIDKOVSKIY, 1959; MOLYAVKO, 1960; BARG, 1993; BARG & IVANOVA, 2000) and industrial-geological reports (1947–2015) were also utilised. The selection and determination of all species of foramini- fera was made from 300 g of sediment sample that was previously washed through a 76 μm sieve (e.g. VERNIGOROVA et al., 2006; VERNIGOROVA, 2008). Descriptions and images of foramini- Tokmachka M ol oc hn a Vovcha Sam ar a D ni pr o Inhul et s V ys un Saksah an In hu l Pivdennyi Buh Kropyvnytskyi Kamianske Pavlohrad Kryvyi Rih MarhanetsNikopol Melitopol Berdiansk Dzhankoi Kerch Feodosiia Yalta Sevastopol Yevpatoriia Dnipro Zaporizhzhia Kherson Simferopol Mykolaiv II II I I V V III III IV IVMekenziev Strata Hladkivka Formation Tymoshivka Formation VI Petrovske FormationNovokakhovka Formation Tarkhankut Formation VI UKRAINE – Crimean Peninsula – Northern Black Sea Region – Kerch Peninsula Location of the study area 8z 9 6 8m 20 8z; 9; 6; 8m; 20 – investigated Wells Fig. 4 Vernyhorova Figure 4. Location map of the studied wells in different facies of the Eastern Black Sea Region and the Kerch Peninsula. G eologia C roatica Vernyhorova Yuliia: Biostratigraphy of the Konkian (Middle Miocene of the Eastern Paratethys) deposits of Southern Ukraine based on foraminifera 139 fera from the Neogene deposits of the Eastern Paratethys were used for their species determination (KRASHENINNIKOV, 1959; BOGDANOWICZ, 1952; DJANELIDZE, 1970; BU- GROVA et al., 2005). Molluscs were extracted first, both from the vicinity of the wells and then during sample processing in the laboratory. Traditional conchological methods were used to iden- tify molluscs (ILYINA, 1993; NEVESSKAYA et al., 1993). The number of tests of each foraminifera species was counted in each sample for each well. Species were considered dominant when their percentage of tests was more than the percentage of tests of other species. The foraminiferal assemblages were com- pared based on the similarity of foraminifera species composition and the presence of the same dominant species. A definition of normal–marine, euryhaline, and mixed foraminiferal assemblages became possible after assessment of the palaeoecological charac- teristics of the foraminifera species composition of each assem- blage. Comprehensive analysis of the data obtained from the Konkian stratigraphy of the Southern Ukraine is represented here. Descriptions and graphic presentation of qualitative and quantita- tive analyses of foraminiferal assemblages in the Konkian depo- sits from each of these wells is described in detail in: VERNI- GOROVA, 2008, 2009, 2012; VERNIGOROVA et al., 2009. Palaeoecological characteristics of foraminifera and mol- luscs (their classification as stenohaline, normal-marine and eu- ryhaline species) is based on data from: ARKHANGUELSKY, ed., 1940; MERKLIN, 1953; DIDKOVSKIY & KULICHENKO, eds., 1975; MURATOV & NEVESSKAYA, eds., 1986; DIDKO- VSKIY, 1959; KRASHENINNIKOV, 1959; BOGDANOWICZ, 1965; DJANELIDZE, 1970; ILYINA, 2000; MAISSURADZE et al., 2014; ZHGENTI & MAISSURADZE, 2016, etc. Analysis of changes of foraminifera and molluscs species composition gave possibility to understand the peculiarities of the development of different regions of southern Ukraine in Konkian time. Palaeoecological and stratigraphic reconstruction of the middle Miocene deposits of the Eastern Black Sea Region was created using palaeoecological, bio- and lithostratigraphic data that were obtained both from published literature and the author’s research (e.g. ARKHANGUELSKY, ed., 1940; DIDKO- VSKIY, 1959; MOLYAVKO, 1960; BARG, 1969, 2008; PRISYAZHNYUK et al., 2007; VERNIGOROVA, 2008, 2009, 2012; VERNIGOROVA et al., 2009; VERNYHOROVA, 2014, 2015b, 2016). 5. RESULTS AND DISCUSSION 5.1. Peculiarities of foraminifera and molluscs assemblages in the Konkian deposits of the studied area Five stenohaline normal-marine (NM1-NM5), two euryhaline (EH1, EH2) and one mixed (MX) foraminiferal assemblages were identified within the cores of the investigated wells at different levels (Figs. 7, 8). They are characterized by the predominance of either normal-marine or euryhaline foraminiferal taxa (e.g. KRASHENINNIKOV, 1959; BOGDANOWICZ, 1965; DJANELIDZE, 1970; KRASHENINNIKOV et al., 2003) or an equal number of marine and euryhaline foraminiferal taxa (DID- KOVSKIY, 1959; VERNIGOROVA, 2012) accordingly. Assemblage NM1 is characterized by dominant species: Quinqueloculina minakovae ukrainica, Q. pseudoangustissima KRASHENINNIKOV, Q. ex gr. consobrina ORBIGNY, Variden­ tella reussi sartaganica, Triloculina inflata ORBIGNY, T. ebersini DIDKOVSKIY, Globulina gibba ORBIGNY and subdominant species: Triloculina inornata ORBIGNY, Spiroloculina konkensis BOGDANOWICZ, Sigmoilina sp., Florilus boueanus ORBIGNY, Nonion sp.1, Elphidium joukovi SEROVA, Ammonia ex gr. bec­ carii (LINNÉ). It was determined in three wells in the eastern part Figure 5. Stratigraphic scheme of the Konkian deposits of the Southern Ukraine (according to VERNYHOROVA, 2014, 2015a, b, 2016). G eo lo gi a C ro at ic a Geologia Croatica 71/3140 -5 0,0 +5 -70 -65 -60 -55 -50 -45 -40 -35 -30 -25 -20 -15 -15 Well 8z Well 9 Well 6 Well 8m Well 20 ab so lu te el ev at io n43,0 km West East 17,0 km West East 40,9 km North South 182 km North South 84,3 88,5 N1mc 82,2 84,0 N1Chk 90,0 100,0 N1S2 85,0 90,0 16,2 67,2 N1S1 N1S1 N1S1 N1S1 N1Krg Tokmachka Marhanets Melitopol Berdiansk Dzhankoi Kerch Feodosiia Zaporizhzhia 8z 9 6 8m 20 * – 8z; 9; 6; 8m; 20 – investigated Wells * * * * * V VI III I II II I V III Mekenziev Strata Tymoshivka Formation VI Petrovske Formation The Legend of wells see on Fig. 8Novokakhovka Formation Tarkhankut Formation Figure 6. Location of the wells and schematic section of the Konkian deposits from Wells 8z, 9, 8m, and 20. G eologia C roatica Vernyhorova Yuliia: Biostratigraphy of the Konkian (Middle Miocene of the Eastern Paratethys) deposits of Southern Ukraine based on foraminifera 141 of the Northen Black Sea Region (Figs. 6, 8). The Well 8z (88.3- 87.8 m) is characterized by the interbedding of light yellow-grey and green-grey loose or dense argillaceous limestones. Well 9 (83.0-82.65 m) is characterized by light-gray with a greenish tinge, dense, laminated, carbonate clays with sandy grains on bedding planes. Well 6 (87.15-87.0 m) is characterized by black with a greenish tinge argillite clays. Different molluscs were found to- gether with this foraminiferal assemblage (Figs. 7, 8). Namely, rare shells of Mytilaster volhynicus (EICHWALD), Ervilia pusilla tri­ gonula SOKOLOV, Gibbula aff. bajarunasi (KOLESNIKOV), Nassarius aff. karaganicus (ZHIZHCHENKO) were observed in Well 8z; similar molluscs species composition and also many shells of Ervilia pusilla trigonula were found in Well 9; Nassarius aff. karaganicus, Ervilia pusilla trigonula and rare Hydrobia sp., Alvenius nitidus (REUSS) were found in Well 6. These are nor- mal-marine mollusc assemblages (Fig. 7) or Sartagan Beds (in the sense of MERKLIN, 1953; MURATOV & NEVESSKAYA, eds., 1986). Also the numerous shells of ostracods, remnants of bryo- zoans and echinoid radiole were found together with this forami- niferal assemblage (Figs. 7, 8). Assemblage NM2 is characterized by a small number of specimens of: Quinqueloculina gracilis KARRER, Q. aff. guri­ Fo ra m in ife ra l a ss em bl ag es W el ls (in te rv al , m ) Beds with predominance of normal-marine species Beds with predominance of euryhaline species assemblage NM1 assemblage NM2 assemblage NM3 assemblage NM4 assemblage NM5 Mixed assemblage MX assemblage EH1 assemblage EH2 Dominant species: R. spinulosa, S. austriaca, S. aff. bidentata, D. cf. haueri, B. melo Subdominant species: V. reussi sartaganica, Nonionella ventragranossa, N. tauricus, El. antonina, Elphidium sp. Normal-marine: Well 6 Anadara turonica, V. (Polititapes) vitaliana, P. praeplicata, E. pusilla trigonula, Obsoletiforma lithopodolica ruthenica, Retusa sp., N.millepunctata In upper parts of some Konkian sections The same species compositions as EH1 assemblage and also admixture of shells of the Early Sarmatian species: E. reginum, E. horridum, Q. consobrina sarmatica, Articulina sp., Entosolenia sp. Euryhaline: Well 8z rare shells of Hydrobia sp., E. pusilla trigonula, Alvenius nitidus and some terrestrial species Shells detritus and rare small shells of Cardium sp. Well 20: 18,1-16,2 m Different quantitaties of shells throughout the section: Q. gracilis, Q. guriana, B. floridana, B. dilatata, N. elongata, U. gracilissima, Fursenkoina schreibersiana, G. aff. austriaca, D. kartvelicus, Cassidulina sp. Rare shells throughout the section Well 20: 45,7-18,1 m S. konkensis, Alvenius nitidus, Mactra sp., and shells detritus Beds with Pholadidae Well 20: 54,7-45,7 m many shells of Barnea pseudoustjurtensis and shells detritus Dominant species: P. subgranosus, El. macellum, A.ex gr. beccarii Subdominant species: Fl. boueanus, Q. aff. guriana, V.reussi sartaganica, Discorbis sp., N. tauricus, El.joukovi Euryhaline: Well 6: 88,5-87,5 m 87,35-87,3 m; 8m: 96,2-93,8 m 93,0-91,6 m 91,1-90,0 m A. nitidus, E. pusilla, Venus sp. Beds with Pholadidae Well 8m: 100,0-97,8 m 96,4-96,2 m Beds with Ervilia Well 9: 84,0-83,93 m; Well 6: 86,6-85,8 m many shells of E. pusilla trigonula Equal quantities of shells: Large shells of euryhaline species: Porosononion subgranosus, E. aculeatum, A. ex gr. beccarii and small shells of stenohaline species: B. dilatata, N. elongata, U. gracilissima, Fursenkoina schreibersiana, G. aff. austriaca, R. spinulosa, Discorbis sp.1, Cassidulina sp. Euryhaline and Spirialis: Well 8m: 96,7; 93,5 m Alvenius nitidus, E. pusilla trigonula, Cardium sp., Venus sp. and plus Spiratella sp. Shells detritus Well 9: 83,7-83,5 m 83,3-85,8 m Well 6: 88,0-87,5 m 87,0-86,6 m Beds with Pholadidae Well 9: 83,50-83,32 m many shells of Barnea pseudoustjurtensis and shell detritus Small sizes, poor preservation, small number of shells: Q. gracilis, Q. minakovae ukrainica, Q. ex gr. consobrina, Q. aff. guriana, Q. angustissima, V. reussi sartaganica, T. inflata, G.gibba, D. supinus, D. squamulus, Spirolina sp., F. boueanus, Nonion sp., A. ex gr. beccarii Beds with Pholadidae: Well 8 many shells of Barnea pseudoustjurtensis single shells of E. pusilla trigonula, Hydrobia sp. Equal quantities of shells: H. aff. podolica, Hauerina sp. 1, Hauerina sp. 2, Discorbis sp. 1, Discorbis? sp. 2 Beds with Ervilia and Pholadidae: Well 8z many shells of E. pusilla trigonula, Barnea pseudoustjurtensis, Hydrobia sp. and shells detritus Dominant species: Q. minakovae ukrainica, Q. pseudo- angustissima, Q. ex gr. consobrina, V. reussi sartaganica, Triloculina inflata, T. ebersini, Globulina gibba Subdominant species: T. inornata, S. konkensis, Sigmoilina sp., F. boueanus, Nonion sp.1, E. joukovi, A. ex gr. beccarii Normal-marine: Well 8z rare shells of M. volhynicus, E. pusilla trigonula, G. aff. bajarunasi, N.aff. karaganicus; Bryozoans, echinoid radiole Well 9 similar on well 8z but has also many shells of Ervilia pusilla trigonula; Bryozoans, echinoid radiole Well 6 N. aff. karaganicus E.pusilla trigonula, rare:Hydrobia sp., Al.nitidus, Bryozoans, echinoid radiole 8z (88,5-87,8m); 9 (83,0-82,65 m); 6 (87,15-87,0 m) 8z (87,8-87,0 m) 8z (86,9-86,3 m) 6 (87,3-87,2 m 85,8-85,0 m) 20 (67,2-18,1 m) Kerch Peninsula Eastern part of the Nothern Black Sea RegionEastern part of the Nothern Black Sea Region Kerch Peninsula 9 (83,7-83,0 m); 6 (87,0-86,6 m); 8m (96,75-96,7 m 93,5-93,45 m) 9 (84,0-83,7m); 6 (88,5-87,5 m 87,35-87,3 m 86,6-85,8 m); 8m (100,0-96,5 m) 8z (86,3-84,3 m); 20 (18,1-16,2 m) M ol lu sc s as se m bl ag es Figure 7. General characteristics of foraminiferal and mollusc assemblages in the studied Wells (for detailed analyses of these assemblages in the Konkian depo­ sits of each of these wells see also: PRISYAZHNYUK et al., 2007; VERNIGOROVA, 2008, 2009, 2012; VERNIGOROVA et al., 2009). G eo lo gi a C ro at ic a Geologia Croatica 71/3142 NM1 EH1 NM NM EH 16,2 18,0 20,0 22,0 24,0 26,0 28,0 30,0 32,0 34,0 36,0 38,0 40,0 42,0 44,0 46,0 48,0 50,0 52,0 54,0 56,0 58,0 60,0 62,0 64,0 66,0 67,2 K o n k ia n T h ic k n e s s 5 1 ,0 m lower Sarmatian (Volhynian) N1S1 lower Sarmatian (Volhynian) N1S1 middle Sarmatian (Bessarabian) N1S2 lower Sarmatian (Volhynian) N1S1 lower Sarmatian (Volhynian) N1S1 Karaganian N1Krg EH2 NM5 S he lls d et rit us a nd ra re s he lls o f S pi ra te lla k on ke ns is , A lv en iu s ni tid us , M ac tra s p. S he lls d et rit us Sh el ls d et rit us an d ra re s m al l sh el ls o f C ar di um s p. – Alvenius – Ervilia – Shells detritus– Bivalvia– Hydrobia– Gastropoda– Barnea be ds w ith P ho la di da e K o n k ia n T h ic k n e s s 4 ,2 m Mayachka Formation (N1mc)Tarkhanian ? lamination clays aleurites sandstones cloddy clays sands limestones chemogenic limestones gravel and pebbles detritus break in sedimentation Well 9 Tymoshivka village Well 6 Soloviovka village Well 20 Leninske village Well 8m Melitopol town Well 8z Dohmarivka village 88,5 88,0 87,8 87,1 87,0 86,5 86,0 85,5 85,2 85,0 84,5 84,3 EH2 Fo ra m in ife ra l as se m bl ag es M ol lu sc s as se m bl ag es Sh el ls d et rit us ; r ar e H yd ro bi as p. a nd E . p us illa ; in te rla ye r o f s he lls o f t er re st ria l s pe si es (8 4, 7- 84 ,3 m ) NM1 NM NM2 NM3 Redeposited fauna E rv ili a P ho la di da e be ds w ith P ho la di da e 82,65 82,70 82,75 82,80 82,85 82,90 83,00 83,10 83,21 83,32 83,43 83,54 83,65 83,76 83,87 84,00 K o n k ia n T h ic k n e s s 1 ,7 8 m Rumpled layer with redeposit fauna of Chokrakian and Karaganian ages NM1 NM MX EH1 Fo ra m in ife ra l as se m bl ag es M ol lu sc s as se m bl ag es B ar ne a Ervilia S he lls de tri tu s S he lls de tri tu s 85,0 86,0 88,0 89,0 90,0 87,0 K o n k ia n T h ic k n e s s 5 ,0 m The well was stopped NM4 EH1 EH1 NM EH1 NM4 MX Fo ra m in ife ra l as se m bl ag es M ol lu sc s as se m bl ag es euryhaline Sh el ls de tri tu s EH EH normal-marine Molluscs assemblages NM S he lls de tri tu s Be ds w ith Er vi lia 90,0 91,0 93,0 94,0 95,0 92,0 96,0 97,0 99,0 100,0 98,0 K o n k ia n T h ic k n e s s 1 0 ,0 m Fo ra m in ife ra l as se m bl ag es M ol lu sc s as se m bl ag es The well was stopped MX MX EH1 EH1 EH1 EH1 EH1 EH1 EH1 EH1 EH EH1 EH EH be ds w ith P ho la di da ebeds with Ervilia and Pholadidae beds with Ervilia beds with Pholadidae – sampling points the general (isohronous) foraminiferal assemblage for some wells foraminiferal assemblages with different paleoecological characteristic euryhaline assemblage and Spirialis sp. EH Spirialis EH Spirialis MX EH Spirialis Ervilia Barnea Ervilia Barnea Ervilia Barnea Fo ra m in ife ra l as se m bl ag es M ol lu sc s as se m bl ag es EH2 NM3 NM1 NM4 Figure 8. Distribution of foraminiferal and molluscs assemblages in the Konkian deposits of the studied wells. G eologia C roatica Vernyhorova Yuliia: Biostratigraphy of the Konkian (Middle Miocene of the Eastern Paratethys) deposits of Southern Ukraine based on foraminifera 143 ana DJANELIDZE, Q. minakovae ukrainica, Q. ex gr. consob­ rina, Q. pseudoangustissima, Varidentella reussi sartaganica, Triloculina inflata, Globulina gibba, Discorbis supinus, D. squa­ mulus (REUSS), Spirolina sp., Florilus boueanus, Nonion sp., Ammonia ex gr. beccarii. It was determined in Well 8z (87.8-87.0 m) in the eastern part of the Northen Black Sea Region (Figs. 6, 8). This interval is characterized by dark grey viscous clays with aleurite powders grains on bedding planes. The numerous mol- lusc shells of Barnea pseudoustjurtensis and fragments of Ervilia pusilla trigonula and Hydrobia sp. were found together with this foraminiferal assemblage (Figs. 7, 8). These are Beds with Pholadidae (Fig. 7) or Kartvel Beds (in the sense of Merklin, 1953; MURATOV & NEVESSKAYA, eds., 1986). Assemblage NM3 is characterized by equal quantities of poorly preserved tests: Hauerina podolica SEROVA, Hauerina sp. 1, Hauerina sp. 2, Discorbis sp. 1, Discorbis? sp. 2. It was de- termined in Well 8z (86.9-86.3 m) in the eastern part of the North- ern Black Sea Region (Figs. 6, 8). These deposits are character- ized by interbeddings of greenish-light-grey aleurites and darker clays. The numerous mollusc shells of Barnea pseudoustjurten­ sis, Ervilia pusilla trigonula and single shells of Hydrobia sp. were found together with this foraminiferal assemblage (Figs. 7, 8). These are Beds with Ervilia and Pholadidae (Fig. 7) or the Kartvel Beds (in the sense of BARG, 1969). Assemblage NM4 is characterized by the dominant species: Reussela spinulosa, Spirolina austriaca ORBIGNY, Dendritina cf. haueri ORBIGNY, Borelis melo and subdominant species: Varidentella reussi sartaganica, Nonionella ventragranossa KRASHENINNIKOV, Nonion tauricus, Elphidium antonina KRASHENINNIKOV, Elphidium sp. It was determined in two levels of Well 6 (87.3-87.2 m; 85,8-85.0 m) in the eastern part of the Northern Black Sea Region (Figs. 6, 8). These deposits are characterized by greenish-dark-grey dense clays. The numerous mollusc shells have been found together with this foraminiferal assemblage (Figs. 7, 8). There are Anadara turonica (DUJAR- DIN), Venerupis (Polititapes) vitaliana (ORBIGNY), Plicati­ forma praeplicata (HILBER), Ervilia pusilla trigonula, Obso­ letiforma lithopodolica ruthenica, Retusa sp., Natica millepunctata LAMARK. These are normal-marine molluscs as- semblages (Fig. 7) or Sartagan Beds (in the sense of Merklin, 1953; MURATOV & NEVESSKAYA, eds., 1986). Assemblage NM5 is characterized by different abundances of foraminiferal tests in each sample without an obvious predomina- tion of a particular species: Quinqueloculina gracilis, Q. guriana, Bolivina floridana CUSHMAN, B. dilatata REUSS, Neobulimina elongata (ORBIGNY), Uvigerina gracilissima POBEDINA, Fursenkoina schreibersiana (CZJZEK), Guttulina aff. austriaca ORBIGNY, Discorbis kartvelicus, Cassidulina sp. It was deter- mined in Well 20 (67.2-18.1 m) in the western part of the Kerch Peninsula (Fig. 6, 8). These deposits are characterized by grey to light grey dense, thinly-laminated clays sometimes sandy, with aleurite powders on interbeddings. Rare mollusc shells of Limacina konkensis (ZHIZHCHENKO), Alvenius nitidus, Mactra sp., and shell detritus were found together with this foraminiferal assem- blage (Figs. 7, 8). In addition, many shells of Barnea pseudoustjur­ tensis were found only in one part of the deposits (Well 20: 54.7- 45.7 m) and these are Beds with Pholadidae (Fig. 7) or the Kartvel Beds (in the sense of MERKLIN, 1953; MURATOV & NEVESS- KAYA, eds., 1986). Assemblage EH1 is characterized by dominant species: Po­ rosononion subgranosus (EGGER), Elphidium macellum (FICH- TEL & MOLL), Ammonia ex gr. beccarii and subdominant spe- cies: Florilus boueanus, Q. aff. guriana, Varidentella reussi sartaganica, Discorbis sp., Nonion tauricus, Elphidium joukovi. It was determined in two Wells: 9 (84.0-83.7 m); 8m (in several samples in interval 100.0-96.5 m) and on three levels of Well 6 (88.5-87.5 m; 87.35-87.3 m; 86.6-85.8 m) in the eastern part of the Northern Black Sea Region (Fig. 6, 8). These deposits are charac- terized by greenish-dark-grey clays (Well 9); light-grey laminated clays with aleurite powders on interbeddings (Well 8m: 96.5-98.8 m), light-grey with a greenish tinge fine-grained, sometimes clayey quartz sands (Well 8m: 98.5-100.0 m ); interbeds of green- ish-dark-grey dense clays and light-grey sandstones, with inter- beds of light-grey quartz sands (Well 6: 88.5-87.3 m, 87.35-87.3 m, 86.6-85, 8 m). Different molluscs were found together with this assemblage (Fig. 7, 8). Rare mollusc shells of Alvenius nitidus, Er­ vilia pussila trigonula, Venus sp. were found together with this foraminiferal assemblage in Well 6 (88.5-87.3 m, 87.35-87.3 m) and in Well 8 (96.2-93.8 m; 93.0-91.6 m; 91.1-90.0 m). These are euryhaline mollusc assemblages (Fig. 7) or Veselyanka Beds (in the sense of Merklin, 1953; MURATOV & NEVESSKAYA, eds., 1986). Also, many shells of Barnea pseudoustjurtensis were found only in Well 8 (100.0-97.8 m; 96.4-96.2 m). These are Beds with Pholadidae (Fig. 7) or Kartvel Beds (in the sense of MERKLIN, 1953; MURATOV & NEVESSKAYA, eds., 1986). And also many shells of Ervilia pussila trigonula and mollusc detritus were found in Wells 9 and 6 (86.6-85.8 m). These are Beds with Ervilia and Pholadidae (Fig. 7) or Kartvel Beds (in the sense of BARG, 1969). Assemblage EH2 is characterized by the same species com- position as assemblage EH1 but also comprises some tests of the Early Sarmatian species: Elphidium reginum (ORBIGNY), E. horridum, Quinqueloculina consobrina sarmatica GERKE, Ar­ ticulina sp., Entosolenia sp. This assemblage was determined in the upper part of the Konkian deposits before the Konkian/Sar- matian boundary in Well 8z (86.3-84.3 m) in the eastern part of the Northern Black Sea Region and Well 20 (18.1-16.2 m) in the western part of the Kerch Peninsula (Fig. 6, 8). It characterizes the final development stage of the Konkian basin (VERNY- HOROVA, 2015a, b, 2016). These deposits are characterized by interbeds of greenish-light-grey aleurites and clays, bluish-light- grey non-laminated carbonate clays at the top of the interval (Well 8z); grey aleuritic, massive, thick-laminated clays with aleurite powders on interbeddings (Well 20). Rare mollusc shells of Hydrobia sp., Ervilia pusilla trigonula, Avenius nitidus and some terrestrial species in Well 8z and shells detritus with scarce small shells of Cardium sp. (Well 20) were found together with this assemblage (Figs. 7, 8). The Konkian age of deposits with this assemblage was confirmed in Well 8z by molluscs and ostra- cods (PRISYAZHNYUK et al., 2007). Assemblage MX is characterized by equal abundance of large tests of euryhaline species: Porosononion subgranosus, El­ phidium aculeatum, Ammonia ex gr. beccarii and small tests of stenohaline species: Bolivina dilatata, Neobulimina elongata, Uvigerina gracilissima, Fursenkoina schreibersiana, Guttulina aff. austriaca, Reussela spinulosa, Discorbis sp.1, Cassidulina sp. This assemblage was determined in different levels of three Wells: 9 (83.7-83.0 m); 6 (87.0-86.6 m); 8m (96,75-96,7 m; 93,5- 93,45 m) in the eastern part of the Northern Black Sea Region. These deposits are characterized by light-grey carbonate dense clays (Well 9); black with a greenish tinge dense clays (Well 6); light-grey laminated clays with aleurite grains on interbeddings (Well 8m: 96.75-96.7 m) light-grey fine-grained, carbonate sand- stones (Well 8m: 93.5-93.45 m). Different molluscs were found together with this assemblage (Fig. 7, 8). Namely, rare mollusc shells of Alvenius nitidus, Ervilia pusilla trigonula, Cardium sp., Venus sp. and Limacina sp. (mixed mollusc assemblage) were G eo lo gi a C ro at ic a Geologia Croatica 71/3144 found in Well 8m; the numerous molluscs shells of Barnea pseu­ doustjurtensis (Beds with Pholadidae – in the sense of MERK- LIN, 1953; MURATOV & NEVESSKAYA, eds., 1986) were found in a thin layer in Well 9 (83.5-83.32 m); shells detritus were found in Well 6 and Well 9 (83.7-83.5; 83.32-83.0 m). 5.2. Biostratigraphic reconstruction of the Konkian deposits of the Southern Ukraine based on foraminifera Shallow-water Konkian deposits of the Eastern Black Sea Region (Tymoshivka Formation) contain several foraminiferal assem- blages with different taxonomic composition and palaeoecologi- cal characteristics. They occur together with different mollusc assemblages (Figs. 7, 8). Normal-marine foraminiferal assem- blages (NM1-NM4) are accompanied by adequate mollusc as- semblages (single levels of Wells 8z; 9; 6) and also by Beds with Pholadidae and by Beds with Ervilia and Pholadidae (two levels of Well 8z). The euryhaline foraminiferal assemblages (EH1; EH2) are accompanied by euryhaline mollusc assemblages (dif- ferent levels of Wells 6; 8m) and also by Beds with Pholadidae and by Beds with Ervilia (different levels of Wells 9; 6; 8m). A mixed foraminiferal assemblage (MX) is accompanied by mixed mollusc assemblages (two levels of Well 8m) and also by Beds with Pholadidae (single level of Well 9). Also, some levels with different foraminiferal assemblages are composed only of the de- tritus of mollusc shells (different levels of Wells 8z; 9; 6). All these foraminiferal assemblages as well as mollusc assemblages have different and irregular positions in the Konkian deposits of the various wells. A similar sequence of such assemblages was found in the Konkian sections of shallow-water deposits in other areas of the Northern Black Sea Region (Hladkivka Formation, Novokakhovka Formation) and in the Crimean Peninsula (Mek- enziev Strata, Tarkhankut Formation, Novokakhovka Formation) (e.g. DIDKOVSKIY, 1959; BARG, 1969, 2008; IVANOVA, 2012; VERNYHOROVA, 2015b, 2016, etc.). The distribution of Konkian foraminiferal assemblages in more deep-water deposits of the Kerch Peninsula is significantly different from deposits of the coeval shallow-water sediments of the Northern Black Sea Region and the Crimean Peninsula. The lower and much thicker part of these deposits contains a normal- marine foraminiferal assemblage with a predominance of steno- haline species (Figs. 7, 8). A significant rearrangement of the spe- cies composition is observed only in the upper part of the Konkian deposits below the Konkian/Sarmatian boundary. These deposits contain a depleted foraminiferal assemblage with a predomi- nance of euryhaline species and a minor admixture of the early Sarmatian species. The Kerch foraminiferal assemblages are si- milar to those from the relatively deep-water Konkian sediments of the Taman Peninsula and the Western Ciscaucasus (e.g. BOG- DANOWICZ, 1965; GOLOVINA et al., 2009; VERNIGOROVA et al., 2006; POPOV et al., 2016; PALCU et al., 2017). The analysis of foraminiferal assemblages with different spe- cies composition and palaeoecological characteristics revealed a common assemblage (NM1) in three Wells (8z; 9; 6) of the East- ern Black Sea Region (Figs.7; 8). Marine molluscs, bryozoans and echinoid radiole were also found together with this assemblage. Small distances between these Wells (43 and 17 km accordingly – see Fig. 6) allow consideration of these deposits with identical fauna as an isochronous level. This level was used as a bench- mark for stratigraphic correlation, for identification of hiatuses and also for the reconstruction of palaeoenvironmental condi- tions during Konkian time in the research area. Namely, if we assume that the HM1 assemblage in different Wells was formed West East H i a t u s H i a t u s H i a t u s H i a t u s H i a t u s K on ki an S ar m at ia n lo w er K ar ag an ia n m id d le M io c e n e C ho kr ak ia n Ta rk ha ni an Mayachka Formation (age is under discussion because fauna is absent) Mayachka Formation (age is under discussion because fauna is absent) ? Hryhoriivka FormationKrasnoperekopsk Formation T y m o s h i v k a F o r m a t i o n euryhalinenormal-marineFaunal assemblages: beds with Ervilia and Pholadidaemixed The legend of the rocks is shown at the Fig. 8 Figure 9. Palaeoecological and stratigraphic reconstruction of the middle Miocene deposits of the Eastern Black Sea Region. G eologia C roatica Vernyhorova Yuliia: Biostratigraphy of the Konkian (Middle Miocene of the Eastern Paratethys) deposits of Southern Ukraine based on foraminifera 145 contemporaneously then deposits with this assemblage represent a single biostratigraphic level and a marker for the stratigraphic evaluation of other horizons. The final phase of development of the Konkian basin was determined in the upper part of Well 8z (the Eastern Black Sea Region) and Well 20 (the Kerch Peninsula) (Figs. 7, 8) based on the presence of the special foraminiferal assemblage (EH2) in these deposits. Combining the data on changes of foraminiferal and molluscs assemblages with other bio- and lithostratigraphic data concern- ing the middle Miocene sediments of the investigated area (e.g. ARKHANGUELSKY, ed., 1940; DIDKOVSKIY, 1959; MOL- YAVKO, 1960; BARG, 1969, 2008; PRISYAZHNYUK et al., 2007; VERNIGOROVA, 2008, 2009, 2012; VERNIGOROVA et al., 2009; VERNYHOROVA, 2015b; 2016) allowed the creation of palaeoecological and stratigraphic reconstruction of the middle Miocene sediments in the Eastern Black Sea Region (Fig. 9). 6. СONCLUSIONS The study of spatial and temporal changes of foraminiferal as- semblages in the Konkian deposits of Southern Ukraine indicate that the shallow-water basin of the Eastern Black Sea Region and the more deep-water basin of the Kerch Peninsula had different models of development during most of the Konkian period. Two foraminiferal assemblages with different palaeoecolo- gical characteristics in the studied deposits of the Kerch Penin- sula indicate two successive development phases of the relatively deep-water Konkian basin of this area. During the first, longer part of the Konkian, relatively stable marine conditions predo- minated, while the late period of existence of this palaeobasin is characterized by a sharp change to euryhaline conditions. Changes in foraminiferal assemblages in relatively deeper-water Konkian deposits of the Kerch Peninsula and the Ciscaucasus are similar. This indicates that basins with such types of sediments in the Eastern Paratethys had a similar pattern of development during the Konkian. Many irregular vertical and lateral changes of foraminiferal assemblages with different palaeoecological characteristics and hiatuses observed in the shallow-water Konkian deposits of the Eastern Black Sea Region indicate that the palaeobasin in this area was influenced by frequent and abrupt changes in environmental conditions during most of the Konkian. Palaeoecological and litho- logical characteristics of the Konkian deposits of the Eastern Black Sea region are similar to those of other shallow-water coeval deposits of the Southern Ukraine, and it can be concluded that the development of the entire Northern Black Sea Region and most of the Crimean Peninsula were similar during this time period. The late development phase of the Konkian was the same in both shallow-water deposits of the Eastern Black See region and more deep-water deposits of the Kerch Peninsula deposits. 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