The Cenozoic succession in the Lower Kura Basin includes largely uniform, often carbonate-free mudstones. Because age dating of these sediments has proved difficult, the stratigraphy of the Cenozoic succession and the distribution of organic-rich strata are poorly known. A better understanding of the Cenozoic succession is not only important for petroleum-systems-analysis, but also for the understanding of the Cenozoic evolution of the Caucasus region. Therefore, bulk geochemical data (carbonate, TOC, sulphur, Rock-Eval) of 885 samples and biostratigraphic data were collected along seven outcrop profiles. This enabled the establishment of a continuous stratigraphic record from the Middle Eocene to the Late Miocene (Pontian). The study results show that potential source rocks are present in three stratigraphic units: the Middle Koun (Middle Eocene), Maikop Group (OligoMiocene) and Diatom Formation (Upper Miocene). The Middle Koun is about 100 m thick near the Caspian Sea and contains highly oil-prone sediments (2-24 wt% TOC; HI 300-577 mgHC/gTOC), which may generate 1.5 tHC/m(2). The Maikop Group contains on average 1.8 wt% TOC, but is often gas-prone. Highly oil prone layers (2-5 wt% TOC; HI 300-450 mgHC/gTOC) are rare. Nevertheless, the Upper Maikop Formation may generate similar to 2 tHC/m(2). The Diatom Formation contains paper shales with high TOC contents (3-22 wt%) and HI values (350-770 mgHC/gTOC). The paper shale unit is more than 60 m thick near the Caspian Sea and can generate 3.8 tHC/m(2). Previously it was thought that the Maikop Group had the highest petroleum potential, whilst Upper Miocene and Middle Eocene source intervals were overlooked. The Middle Eocene to Lower Oligocene succession in the Kura Basin is largely carbonate-free. In contrast, coeval successions elsewhere in the Caucasus region contain sediments with varying, but often high carbonate contents. Differences in carbonate content imply greater water depth during deposition in the Kura Basin.

Extensive bulk sampling of seven horizons of a continuous succession deposited in an outer neritic environment of the latest Maastrichtian yielded more than three thousand ichthyoliths, including 1347 elasmobranch teeth. The sampled succession represents a characteristic deep-water fauna dominated by small squaliform sharks with an increase of species richness towards the end of the Cretaceous. The multidisciplinary approach of precise sampling in combination with a well-founded biostratigraphic classification of seven assemblages provides rare and direct evidence of diversity fluctuations within the latest Maastrichtian, immediately before the bolide impact triggered the severe mass extinction event at the K/Pg boundary. Although squaliform sharks dominate the fauna, a conspicuous heterogeneity of species abundance between the assemblages is observed and a noteworthy correlation between squa-liform species richness and the abundance of Parasquatina zitteli (Orectolobiformes) might indicate clade competition for ecological niches. Among 15 elasmobranch species, this study describes one new genus (Fredipristis gen. nov.) and four new squaliform species (F. eximia gen. et sp. nov., Eoetmopterus davidi sp. nov., Proetmopterus lukasi sp. nov., and Cretascymnus beauryi sp. nov.), which highlights the importance and potential of bulk sampling for reconstructing elasmobranch diversity of deep-marine realms through time.(c) 2022 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Due to the peculiar combination of dental features characteristic for different squaliform families, the position of the Late Cretaceous genera Protoxynotus and Paraphorosoides within Squaliformes has long been controversial. In this study, we revise these genera based on previously known fossil teeth and new dental material. The phylogenetic placement of Protoxynotus and Paraphorosoides among other extant and extinct squaliforms is discussed based on morphological characters combined with DNA sequence data of extant species. Our results suggest that Protoxynotus and Paraphorosoides should be included in the Somniosidae and that Paraphorosoides is a junior synonym of Protoxynotus. New dental material from the Campanian of Germany and the Maastrichtian of Austria enabled the description of a new species Protoxynotus mayrmelnhofi sp. nov. In addition, the evolution and origin of the characteristic squaliform tooth morphology are discussed, indicating that the elongated lower jaw teeth with erected cusp and distinct dignathic heterodonty of Protoxynotus represents a novel functional adaptation in its cutting-clutching type dentition among early squaliform sharks. Furthermore, the depositional environment of the tooth bearing horizons allows for an interpretation of the preferred habitat of this extinct dogfish shark, which exclusively occupied shelf environments of the Boreal- and northern Tethyan realms during the Late Cretaceous.

This study investigates the hydrocarbon potential of Oligocene–Miocene shales in the Menilite Formation, the main source rock in the Ukrainian Carpathians. The study is based on the analysis of 233 samples collected from outcrops along the Chechva River in western Ukraine in order to analyse bulk parameters (TOC, Rock‐Eval), biomarkers and maceral composition.In Ukraine, the Menilite Formation is conventionally divided into Lower (Lower Oligocene), Middle (Upper Oligocene) and Upper (Lower Miocene) Members. The Early Oligocene and Early Miocene ages of the lower and upper members are confirmed by new nannoplankton data. The Lower Menilite Member is approximately 330 m thick in the study area and contains numerous chert beds and turbidite sandstones in its lower part together with organic‐rich black shales. The shales have a high content of silica which was probably derived from siliceous micro‐organisms. The TOC content of the shales frequently exceeds 20 wt.% and averages 9.76 wt.%. HI values range between 600 and 300 mgHC/gTOC (max. 800 mgHC/gTOC). The Middle Member contains thin black shale intervals but was not studied in detail. The Upper Member is about 1300 m thick in the study area and is composed mainly of organic‐rich shales. Chert layers are present near the base of the Member, and a prominent tuff horizon in the upper part represents a volcanic phase during shale deposition. The member grades into overlying molasse sediments. The average TOC content of the Upper Menilite succession is 5.17 wt.% but exceeds 20 wt.% near its base.Low Tmax and vitrinite reflectance measurements for the Lower (419°C and 0.24–0.34 %Rr, respectively) and Upper (425°C and 0.26–0.32 %Rr, respectively) Menilite Member successions indicate thermal immaturity. Biomarker and maceral data suggest a dominantly marine (Type II) organic matter input mixed with varying amounts of land‐plant derived material, and indicate varying redox and salinity conditions during deposition.Determination of the Source Potential Index (SPI) shows that the Menilite Formation in the study area has the potential to generate up to 74.5 tons of hydrocarbons per m2. The Chechva River outcrops therefore appear to have a significantly higher generation potential than other source rocks in the Paratethys realm. These very high SPI values for the Menilite Formation may explain why a relatively small area in Ukraine hosts about 70% of the known hydrocarbon reserves in the northern and eastern Carpathian fold‐thrust belt.

For over a century, oil has been produced in Georgia from oilfields located in the foreland basins between the Greater and Lesser Caucasus foldbelts. To date, little information on the associated source rocks has been available. In this context, this paper presents a study of 380 samples of Eocene (Kuma Formation) and Oligocene to Lower Miocene (Maikop Group) source rocks from three outcrop sections in the Rioni and Kura Basins. The Kuma Formation in the Rioni Basin is composed of fully‐marine marls and is about 40 m thick. At the Martivili and Khobi sections, the formation is thermally immature and has an average TOC of 3.2 wt%. The hydrogen indices (HI) of 300–600 mg HC/g TOC indicate that the organic matter is oil‐prone Type II kerogen. The oil generation potential is between 1.0 and 2.4 t HC/m2, and the Kuma Formation is therefore interpreted as a prolific source rock.The Maikop Group in the Rioni Basin was studied at the Martvili section, where it is thermally immature. The Oligocene succession is divided by calcareous shales deposited during the Solenovian Event (at the onset of nannoplankton zone NP23) into Pshekhian and Solenovian‐to‐Kalmykian intervals. The Pshekhian interval (NP21‐22) is over 60 m thick and comprises a marly lower part and a shale‐rich upper part, and contains high quantities (average 2.7 wt% TOC) of Type II‐III kerogen (average HI: 278 mg HC/g TOC). The overlying largely carbonate‐free shale succession, 424 m thick, is less organic matter ‐rich (∼2.0 %TOC) and contains dominantly Type III kerogen (average HI: 140 mg HC/g TOC). In total, the Maikop Group has a generation potential of about 4 t HC/m2, a value which is higher than in most other sub‐basins in the Eastern Paratethys. Because the Rioni Basin continues westwards into the Black Sea, these results are relevant for future exploration in the eastern part of the Black Sea Basin.The Maikop Group in the western Kura Basin in the Tbilisi area is over 3500 m thick and includes numerous sandstone beds. Because of the great thickness of the Maikop Group and the presence of about 3 km of overburden, which was removed during Miocene to Recent unroofing, potential source rocks in the Eocene to Lower Oligocene succession have reached oil window maturities but their hydrocarbon potential is low.

Abstract Oligo-Miocene (‘Maikopian’) deposits are considered the main source rocks in the Black Sea area, although only a few source-rock data are available. Geochemical logs from nine wells are used together with age constraints provided by calcareous nannoplankton, well and seismic data to determine vertical and lateral changes of the source potential. Oligocene rocks overlie Eocene deposits with a major unconformity on the western Black Sea shelf in Bulgaria. A west–east-trending erosional structure (the Kaliakra canyon) developed during Lower Oligocene time and was filled with Oligo-Miocene deposits. Potential source rocks are present in different stratigraphic units, but the most prolific intervals accumulated during time intervals when the isolation of the Paratethys resulted in oxygen-depleted, brackish environments with high bioproductivity. These include Lower Solenovian rocks related to blooms of calcareous nannoplankton, which form an extensive layer outside the Kaliakra canyon. This unit hosts a good potential to generate oil and gas. Diatom-rich, very good oil-prone source rocks accumulated during a second isolation event in the Kozakhurian. Thick sections of these diatom-rich rocks occur within the canyon and are present in thin layers outside of it. High productivity of siliceous organisms is attributed to upwelling within the canyon. All studied units are thermally immature on the shelf.

Abstract Oligocene and Lower Miocene deposits in the Paratethys are important source rocks, but reveal major stratigraphic and regional differences. As a consequence of the first Paratethys isolation, source rocks with very good oil potential accumulated during Early Oligocene time in the Central Paratethys. Coeval source rocks in the Eastern Paratethys are characterized by a lower source potential. With the exception of the Carpathian Basin and the eastern Kura Basin, the source potential of Upper Oligocene and Lower Miocene units is low. In general, this is also valid for rocks formed during the second (Kozakhurian) isolation of the Eastern Paratethys. However, upwelling along a shelf-break canyon caused deposition of prolific diatomaceous source rocks in the western Black Sea. Overall, Oligocene–Lower Miocene sediments in the Carpathian Basin (Menilite Formation) can generate up to 10 t HC m−2. Its high petroleum potential is a consequence of the interplay of very high productivity of siliceous organisms and excellent preservation in a deep silled basin. In contrast, the petroleum potential of Oligocene–Lower Miocene (Maikopian) sediments in the Eastern Paratethys is surprisingly low (often <2 t HC m−2). It is, therefore, questionable whether these sediments are the only source rocks in the Eastern Paratethys.

The Paratethys area extends from Central Europe to the borders of the Caspian Sea in Central Asia and hosts a significant number of petroleum provinces, many of which have been charged by Eocene to Miocene source rocks of supra‐regional significance. These include highly oil‐prone Middle Eocene marls and limestones in the Eastern Paratethys (Kuma Formation and equivalents) which are several tens of metres thick. Estimates of the source potential index (SPI) indicate that the Kuma Formation in the northern Caucasus and the Rioni Basin (Georgia) may generate 1 to 2 tons of hydrocarbons per square metre (tHC/m2). This implies that the Kuma Formation may also be an important and additional source rock in the eastern Black Sea.Oligocene and Lower Miocene pelitic rocks (Maikop Group and equivalents) are considered to be the most important source rocks in the Paratethys. Vertical variations in source potential record different stages of basin isolation that reached a maximum during the Early Oligocene (NP23) Solenovian Event. However major variations exist between different sub‐basins in the Central and the Eastern Paratethys. In the Central Paratethys, the highest quality source rocks occur in the Carpathian Basin where the Menilite Formation, several hundreds of metres thick, can generate up to 10 tHC/m2. Locally the Menilite Formation is about 1500 m thick and continues into the Lower Miocene. In these settings, the Menilite Formation can generate approximately 70 tHC/m2. In the Alpine Foreland Basin (Schöneck and Eggerding Formations) and the Pannonian Basin (Tard Clay Formation), oil‐prone source rocks are restricted to the Lower Oligocene. In the Eastern Paratethys, the best source rock intervals of the Maikop Group are typically associated with the Early Oligocene Solenovian Event. By contrast, with the exception of the Kura Basin in Azerbaijan, the potential of Upper Oligocene and Lower Miocene rocks is often limited. In total, the Maikop Group may generate up to 2 tHC/m2 in the North Caucasus area and 4 tHC/m2 in the Rioni Basin.A particular source rock facies is found in the Western Black Sea where diatomaceous rocks with good oil potential accumulated in the Kaliakra Canyon during Early Miocene time. This facies may generate up to 8 tHC/m2, but is probably limited to shelf‐break canyons.Middle and Upper Miocene rocks are the main source for oil and thermogenic gas in the Pannonian Basin System, and also contributed to thermogenic hydrocarbons in the Moesian Platform and the South Caspian Basin. In addition, Upper Oligocene and Miocene rocks are the source for microbial gas in several basins including the Alpine and Carpathian foredeeps.

The Oligocene to early Miocene fine-grained succession in the Eastern Carpathians includes, from base to top the Lower Menilite (LMM), Bituminous Marl (BMM), Lower Dysodilic Shale (LDSM), and Upper Dysodilic Shale (UDSM) members. These stratigraphic units, constituting the main hydrocarbon source rocks in the Eastern Carpathians, have been studied in an outcrop section to determine its depositional environment and hydrocarbon potential.The LMM contains high amounts of TOC, but because of low thickness its source potential is limited. The organic matter of the overlying BMM is mainly derived from autochthonous marine organisms including bacterial biomass. TOC contents are moderate because of dilution by carbonate minerals. Calcareous nannoplankton dates the BMM into nannoplankton zones NP21-22. Salinity and redox conditions varied from reduced to slightly enhanced and from strictly anoxic to dysoxic. The LDSM contains carbonate-free black shale and sandstone beds deposited in a depositional lobe under anoxic conditions. Despite of high HI values, land plants form a significant part of the organic matter. Channel fill sediments form the top of the LDSM. The lower part of the early Miocene UDSM accumulated in a lobe, whereas its upper part represents a basin plain setting. MITC ratios reflect a trend from slightly enhanced to slightly decreased normal marine salinity. The presence of aryl-isoprenoids suggests a temporary photic zone anoxia controlled by salinity variations. Both marine and terrestrial biomass contributed to the organic matter. A major change towards oxic conditions occurred at the boundary between the UDSM and the overlying Gura Soimului Formation.The studied succession can generate 6 t of hydrocarbons per square meter. All members are oil prone, but yield oil with different biomarker characteristics. This allows the identification of oil generated from different lithostratigraphic units. (C) 2015 Elsevier Ltd. All rights reserved.

The scientific borehole Baden-Sooss penetrates a succession of Badenian (Langhian, Middle Miocene) sediments at the type locality of the Badenian, the old brickyard Baden-Sooss in the Vienna Basin. The sedimentary succession of the 102-m-cored interval consists of more than 95% bioturbated, medium-to-dark gray marly shales with carbonate contents between 11 and 25% and organic carbon contents between 0.35 and 0.65%. Biostratigraphic investigations on foraminifera (mainly lower part of Upper Lagenid Zone) and calcareous nannoplankton (standard zone NN5) indicate an early Badenian (Langhian) age. Cycles in carbonate content, organic carbon content, and magnetic susceptibility have been identified by power spectra analysis. Correlations between the three variables are extremely significant. Using cross-correlation, periods around 40 m correlate significantly with the 100 kyr−1 eccentricity cycle, the ∼20 m periods with the obliquity cycle, and the 15 to 11-m periods with both precession cycles. Wavelet transformation and decomposition of composite periodic functions were used to obtain the position of the cycle peaks in the profile. Cross-correlation with orbital cycles (La2004) dates the Baden-Sooss core between −14.379 ± 1 and −14.142 my ± 9 kyr.

The Oligocene Ruslar Formation is a hydrocarbon source rock in the Kamchia Depression, located in the Western Black Sea area. Depositional environment and source potential of the predominantly pelitic rocks were investigated using core and cuttings samples from four offshore wells. In these wells the Ruslar Formation is up to 500m thick. Based on lithology and well logs, the Ruslar Formation is subdivided from base to top into units I–VI. Dysoxic to anoxic conditions and mesohaline to euhaline salinities prevailed during deposition of the Ruslar Formation. Relatively high oxygen contents occurred during early Solenovian times (lower part of unit II), when brackish surface water favoured nannoplankton blooms and the deposition of bright marls (“Solenovian event”). Anoxic conditions with photic zone anoxia were established during late Oligocene times (units III and IV) and, probably, reflect a basin-wide anoxic event in the Eastern Paratethys during Kalmykian times. Organic carbon content in the Ruslar Formation is up to 3%. Autochthonous aquatic and allochthonous terrigenous biomass contribute to the organic matter. Relatively high amounts of aquatic organic matter occur in the lower part of the Ruslar Formation (units I and II) and in its upper part (unit VI). Diatoms are especially abundant in the lower part of unit VI. The kerogen is of type III and II with HI values ranging from 50 to 400mgHC/gTOC. Units I and II (Pshekian, lower Solenovian) are characterized by a fair (to good) potential to produce gas and oil, but potential sources for gas and oil also occur in the Upper Oligocene units IV–VI.

The calcareous nannoplank-ton was studied in samples from the Grund Formation type locality (sections B, F, G and H). Samples from Grund-Windmuhlberg (W1-W4) were further collected and investigated. The nannofossil assemblages are characterized by biostratigraphically important Helicosphaera waltrans, H. walbersdorfensis and the rare occurrence of discoasterids. Although the marker species Sphenolitus heteromorphus is absent in all samples, the composition of nannofossils enables specification of these deposits as Biozone NN5 of Martini (Lower Badenian). Regular presence of H. waltrans, which is usually limited to a short stratigraphic interval within nannoplankton Zone NN5, enables attribution of these sediments to the Helicosphaera waltrans Horizon (Svabenicka 2002).

Borehole Roggendorf-I was drilled in the Alpine-Carpathian Foredeep (Molasse Basin) north of the Danube (Lower Austria). Biostratigraphic results and the lithological column revealed until now unrecorded Early Badenian (Middle Miocene) cycles. Calcareous nannoplankton was studied from the upper 800 m of a Neogene sequence and foraminifers were examined from the upper 410 m. The upper 2 in to 255 in fine elastic sediments of the Grund Formation (Lower Badenian, nannoplankton Zone NN5, plank-tonic foraminiferal Zone Mt6) show a deepening upward, with a maximum depth corresponding to outer shelf. Paleoecological evaluations demonstrate a distinct warming of the surface water. Down-hole, a elastic sequence follows starting with a gravel bed (347-360 m), and ending with a conglomerate bed on top (255-270 m). The latter is probably the transgressive base of the Grund Formation. The boundary of nannoplankton Zones NN4-NN5 lies within this earlier Badenian cycle, which was deposited on the inner shelf, below 50 in. Limestone and sandstone pebbles originate from the Calcareous Alps and Flysch Unit. The underlying cycle of calcareous silty shales, sands and thin gravel layers belongs to the Laa Formation (Karpatian, nannoplankton Zone NN4; 360612 in). Deposition occurred, partly under dysoxic bottom conditions on the outer shelf to upper bathyal. Surface waters were distinctly cooler than in the Grund Formation due to strong upwelling with nutrient enrichment. The Karpatian is underlain without a distinct unconformity by the Upper Ottnangian brackish Rzehakia ("Oncophora") Beds, fine sands and shales, which are barren of fossils (612-678 m). The lower part of the investigated section belongs to the Ottnangian "Robulus Schlier". Nannoplankton determinations show that this still belongs to nannoplankton Zone NN4. Nannoplankton Zone NN3/4 is recorded on the basis of the occurrence of Sphenolithus belemnos only in the lowermost samples (790-800 m).

Mollusc bearing Neogene strata were collectively designated as "Grund Beds" in the 19(th) century. The different lithostratigraphic formations of these Grund Beds were studied in the Austrian Molasse Basin north of the Danube (Alpine-Carpathian Foredeep). Biostratigraphic methods and paleomagnetic measurements revealed that the entire Karpatian Laa Formation spans nannoplankton Zone NN4. It is transgressive on the Lower Miocene, Ottnangian marine sequences. The upper part of the Laa Formation correlates with the first occurrence of Globigerinoides bisphericus and is correlated in the type locality with the reverse Chron C5Cr and the normal chron C5Cn.2n. A distinct unconformity separates the Karpatian and Bademan sequences. The first Badenian transgression of the Molasse Basin resulted in a elastic sequence which, for the time being, has no lithostratigraphic designation. The lower part belongs to nannoplankton Zone NN4, with the first occurrence of Praeorbulina glomerosa glomerosa (Middle Miocene, Zone M5). The upper part of this basal elastic sequence belongs to nannoplankton Zone NN5. A coarse conglomerate, overlying a further unconformity, is interpreted as the transgression horizon of the fine elastic, more than 250 m thick Grand Formation. It spans nannoplankton Zone NN5 and contains Praeorbulina glomerosa circularis. Higher up in the sections, this species occurs together with Orbulina suturalis (plankton Zone M6). Ostracods and molluscs from the Grund Formation is distinctly different from the Karpatian, and indicate an unambiguously Badenian age. The normal paleomagnetic polarity measured in the type locality of the Grand Formation is interpreted as Chron C5Bn.2n. The Gaindorf Formation is coeval with the Grand Formation, developed along the western coast of the Molasse Basin. The more eastern development of the Mailberg Formation stratigraphically corresponds to the upper part of the Grund Formation with the cooccurrence of Po. glomerosa circularis and O. suturalis. In the Mailberg Formation a reverse magnetization is interpreted as correlating with Chron C5Bn.r.

In this study we present a paleoecological interpretation based on quantitative analysis of middle Karpatian (latest Burdigalian) benthic and planktonic foraminifers and calcareous nannofossils from Hole BL 503 (Wienerberger) drilled at Laa an der Thaya, Lower Austria. Multivariate statistics based on the Bray-Curtis Similarity, non-metric MultiDimensional Scaling (nMDS) and Similarity and Dissimilarity Term Analyses are applied to raw data to identify the ecological gradients subtending the assemblages. Species abundance curves (%) were also plotted. A paleoelimatic curve was obtained using the algebraic sum of planktonic foraminifers warm- and temperate-water indicators (positive) and cool-water indicators (negative) to highlight the paleoelimatic trend during the middle Karpatian. Our data indicate that the sediments drilled at Lau Th. were deposited in water depth not exceeding 200 in, relatively "near shore" in an environment characterized by a generally high concentration of organic matter, suboxic to dysoxic conditions, high nutrient availability, variable salinity and generally cool paleoclimate. On the basis of nannoplankton distribution we also suggest that nutrient availability and upwelling conditions, rather than other ecological factors, control the distribution of calcareous nannoplankton in the Molasse Basin.