The first high-resolution study of the Cenomanian to lower Campanian calcareous nannofossils of two most continuous but poor in macrofossils sections of southwestern Crimea allowed the detailed division of these successions on the basis of standard nannofossil zonations and the correlation with Tethyan and Boreal Upper Cretaceous. After initial Cenomanian sea-level fall, nannofossil assemblages increase their abundance and taxonomic diversity toward the end of Cenomanian. The most of the Cenomanian bioevents are recognised in the sedimentary record. The Cenomanian/Turonian transition is the most stratigraphically intricate interval in the Late Cretaceous Crimean basin. The lowest occurrences (LOs) of Cylindralithus biarcus, Quadrum intermedium, Eprolithus octopetalus, Ahmuellerella octoradiata are identified in the upper Cenomanian. The highest occurrences (HOs) of some stratigraphically important for this time span taxa like Corollithion kennedyi, Cretarhabdus striatus and Axopodorhabdus albianus are found significantly above the levels defined as relevant subzonal boundaries (UC3e, UC4b and UC5b, respectively). The TOC-rich sediments corresponding to Bonarelli Level (OAE2) is intercalated in the upper part of the upper Cenomanian limestones (undivided interval of UC5c-UC6a subzone/zone). Helenea chiastia is scarce in the studied succession and its HO cannot be used for definition of zonal boundary (UC6) and the base of Turonian. The most reliable bioevent closest to the Cenomanian/Turonian boundary in this basin is the LO of Eprolithus moratus (base of UC6b subzone). The middle Turonian to lower Campanian nannofossil assemblages display the succession of the main bioevents similar to those in Tethyan basin, but show earlier LOs of Micula and Reinhardtites in the middle Turonian. Nannofossil biostratigraphy revealed the stratigraphic range of hiatuses in this sedimentary record. Being combined with the levels of the major facies changes, these levels enabled the recognition of five Cenomanian and four Turonian sequence boundaries consistent with the sequence stratigraphy established for Europe. Two sharp erosional surfaces occurred in the upper part of the studied succession correspond to the Coniacian KCo1 and Santonian KSa2 sequences. (c) 2024 Elsevier B.V. and Nanjing Institute of Geology and Palaeontology, CAS. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The first results of the U–Th–Pb isotope dating of detrital zircons (dZr, N = 130, n = 91) from the middle Danian sandstones (63.9–65.3 Ma) of the Cretaceous–Eocene Novorossiisk–Anapa flysch widely developed in the Sochi synclinorium (southern slope of the Western Caucasus) are presented. The maximum and minimum dZr age is 2973 ± 12 Ma and 318 ± 3 Ma, respectively; weighted average age of the four youngest dZr is 322 ± 7 Ma. There are no signs of erosion products of the Jurassic magmatites involved in the structure of the Greater Caucasus and Crimean Mountains into the sedimentary basin, where the Novorossiisk–Anapa flysch was formed. The results have revealed a high degree of similarity between the provenance signals of the Danian sandstones from the Novorossiisk–Anapa flysch, some Paleogene–Neogene and Early Quaternary (Early Pleistocene) sandstones of the Western Caucasus and Western Cis-Caucasia, red-colored Upper Permian and Lower Triassic sandstones of the Moscow syneclise, as well as Late Quaternary alluvium at lower reaches of the Don and Volga rivers draining vast expanses of the Russian Plate. These facts suggest: (1) the absence of eroded mountain structures of the Greater Caucasus and Crimea in the middle Danian; (2) the main volume of detrital material composing the Novorossiisk–Anapa flysch was formed due to the recycling of Permian–Triassic and younger sequences of the Russian Plate.

The results of a palynological study of the middle Eocene-lowermost Oligocene strata of the Shagap and Landzhar outcrop sections (southern Armenia) are presented. A series of stratigraphically important dinoflagellate cyst events were recognized in the uppermost Lutetian-lowermost Rupelian parts of the sections, including the lowermost occurrences of the key-species Rhombodinium draco, Schematophora speciosa, Hemiplacophora semilunifera, Hapsocysta kysingensis, Thalassiphora? cf. rota, Rhombodinium porosum, Glaphyrocysta semitecta, Reticulatosphaera actinocoronata, Stoveracysta ornata-group and Wetzeliella gochtii. Based on the first-order calibrations with calcareous nannoplankton and foraminifers, R. draco first occurs at the Lutetian-Bartonian transition, while the lowermost occurrence of R. actinocoronata is very close to the Bartonian-Priabonian boundary. The analysis of the ratios of palynogroups and dinoflagellate eco-groups permits to interpret the environmental conditions during the accumulation of regional formations: (1) a major marine transgression started at the beginning of the Lutetian and the gradual deepening of the marine basin occurred during the middle-late Lutetian (Arpa Formation); (2) the marine transgression, accompanied by deepening, continued during the early Bartonian, but towards the end of the Bartonian slightly shallower depositional conditions were established (Azatek Formation); (3) the sea continued to gradually become shallower during the Priabonian (Urtsadzor Formation) and, finally, the maximum of regression was observed at the Eocene-Oligocene transition, ending with the establishment of brackish environments at the beginning of Rupelian (Shagap Formation).

The early Aptian Oceanic Anoxic Event 1a (OAE1a, or Selli Event) is widely known from many oceanic and inland sections as an interval of enhanced accumulation of sediments rich in total organic carbon (TOC), associated with the turnover in the global carbon budget and dramatic biotic variations. Our multidisciplinary study of the upper Barremian to lower upper Aptian deposits from the eastern part of Crimean Peninsula allowed us to confirm the presence of a layer that correlates to OAE1a and revealed significant reorganization in the planktonic and benthic foraminifera, nannofossils, ostracod and terrestrial plant communities at this level. The low-calcareous OAE1a deposits from the eastern Crimea lack in TOC that is not typical sedimentological response to this critical event. The OAE1a onset was associated with a nannoconid crisis, occurrence of low-abundance Hedbergella planktonic foraminifera, increased abundance of benthic foraminifera and ostracods and the bloom of Classopolis on the adjacent land. The calcareous microplankton biota was highly oppressed during OAE1a up to total elimination in the core of the event. Benthic assemblages indicate the occurrence of dysoxic conditions at the sea-floor. The absence of organic matter in the deposits of the OAE1a interval points to the low basinal biotic productivity and low input of terrestrial organic matter. We suggest that oligotrophication of the basin was related to the transgressive pulse, which led to small-scale landward moving of the coastal line barriered by coastal highland. The hot arid climatic conditions indicated by terrestrial plants, prevented the supply of nutrients and terrestrial organic matter into the basin that caused low algal and bacterial productivity and prevented accumulation of TOC-rich sediments. The termination of OAE1a coincides with the occurrence of warm humid climate and erosion of ephemeral coastal highland, more likely, built up by soft clayey sediments. The transit restoration of the normal marine biota in the early late Aptian was interrupted in the middle late Aptian by new long-lived regression led to enhanced terrestrial runoff and, possibly, fresh water input killed marine biota and caused the accumulation of low-calcareous clay.

The aim. To study peculiarities and association of psychological and laboratory indicators in patients with cardiovascular diseases (CVD) who underwent COVID-19 to clarify the factors affecting the possibility of developing delayed psychological and cardiovascular adverse events. Methods. The study enrolled 350 patients with COVID-19. Group 1 consisted of 92 patients without CVD, Group 2 – of 258 patients with CVD. Indicators of laboratory and psychological parameters were assessed according to the data of psychological questionnaire using GAD-7 (General Anxiety Disorder-7), PHQ-9 (Patient Health Questionnaire-9), PSS (Perceived Stress Scale) screening scales and SF-36. Parameters of complete blood count and biochemical blood tests were measured during hospitalization and three months after discharge from the monohospital. Results. After three months, in the general group of patients, signs of anxiety and depression were detected in more than 30 % of the examined patients, signs of stress – in 10.4 %. In the group with CVD, psycho-emotional disorders were identified in 1/4 of the patients, and severe stress – in 8 % of those included in the study. In addition, it was registered that the indicators of erythrocyte sedimentation rate, fibrinogen, high-sensitivity C-reactive protein (CRP), homocysteine and IL-6 remained at a higher level in the second group. Correlation analysis showed that the psychological component of health is interconnected with the level of neutrophils (p = 0.044) and fibrinogen (p = 0.050); the physical component of health is correlated with the level of erythrocytes (p = 0.030), hemoglobin (p = 0.015), CRP (p = 0.002), creatine phosphokinase (p = 0.036) and glucose (p = 0.017). Regression analysis revealed that in patients with CVD three months after hospitalization, an increased glucose index contributes to deterioration, and increased hematocrit and mean hemoglobin concentration improve the quality of life of patients. Conclusion. Laboratory markers that maintain the duration of a prolonged vascular reaction, violation of the rheological and metabolic properties of blood, determine the nature of the development of both psychological and cardiovascular complications.

A continuous outcrop of the neritic sediments ranging from the Cretaceous/Paleogene to Eocene/Oligocene boundary is exposed along the Kheu R., Kabardino-Balkaria Republic, southern Russia. High calcareous nannofossil abundance and species diversity in Kheu section make possible the application of various standard calcareous nannofossil zonations for the investigated interval. This provides a direct correlation of the biohorizons used as zonal markers in these zonations and recognition of the stage boundaries in this complete succession, which represents the reference Paleogene section of the NE Peri-Tethys. The carbon and oxygen isotope records revealed a series of excursions correlated to peculiar Paleogene paleoecological events on the basis of nannofossil biostratigraphy. The continuous Maastrichtian/Danian transition displays ca. 1 m thick interval containing only scarce Cretaceous survivors between the highest occurrence (HO) of the most Cretaceous nannofossil taxa and the lowest occurrence (LO) of the Paleogene taxa; this interval is characterized by prominent positive δ13C and δ18O excursions. The Late Danian Event (LDE) is identified as minor δ13C and δ18O excursions in the upper Danian. The base of Selandian stage is defined by the 2nd radiation of fasciculiths, followed by negative δ13C and δ18O shifts corresponding to the Danian/Selandian Transition Event. Mid-Paleocene Biotic Event (MPBE), A, B1/B2, C1/C2 and D1/D2 events are pronounced in the upper Paleocene C and O isotope record. Wide expansion of Discoasterales (Fasciculithus, Heliotrochus, Heliolithus, Discoaster), served as a basis for nannofossil zonations, is featured for this time span. The base of Ypresian (lower Eocene) corresponds to the onset of the carbon isotope excursion (CIE) documented at the base of the TOC-rich bed. This 0.6 m thick sapropelitic bed corresponds to the Paleocene–Eocene Thermal Maximum (PETM) and contains specific nannofossil assemblage known as “excursion taxa”. The high sedimentation rate and completeness of the early Eocene sedimentary succession allowed to record the evolution of Tribrachiatus bramlettei–T. digitalis–T. contortus–T. orthostylus lineage spanning the interval of NP10–NP12 zones. Multiple δ13C and δ18O excursions, occurred in the lower Ypresian sediments, correspond to the early Eocene hyperthermals E1/E2, F1, F2, G, ETM2, I1/I2 and J. The intercalations of a series of TOC-rich layers in the interval ranging the upper NP12 to lower NP13 zones correspond to ETM3 and individual episodes (L-T) of the Early Eocene Climatic optimum (EECO). Long-term cooling trend in the Caucasian basin begins in the uppermost Ypresian (upper NP13 zone). The middle Eocene δ18O record demonstrates a succession of negative excursions occurred against the background of relatively high values. The hyperthermal C21r–H6 is recognized at the base of Lutetian stage defined by the LO of Blackites inflatus. Two later excursions of this time interval corresponding to the Late Lutetian Event (LLE) and Middle Eocene Climatic Optimum (MECO) occur in the enriched in TOC Kuma Fm. (late Lutetian to Bartonian) and fall at the levels with highest TOC concentrations. Nannoplankton assemblages are widely dominated by eurytopic reticulofenestrids during both events, while Chiasmolithus and Discoaster become oppressed that can indicate lower salinity caused by enhanced humidity. The base of Priabonian is defined by the LO of Chiasmolithus oamaruensis and the base of Cribrocentrum erbae acme. These bioevents are preceded by the negative δ13C excursion and very positive δ18O values, possibly correlated to the Priabonian Oxygen Maximum (PrOM). The relatively warm Priabonian time, characterized by recovery of Chiasmolithus, Discoaster and Sphenolithus, gives way to a new cooling phase known as Late Eocene Event (LEE). The base of Clausicoccus subdistichus acme, approximated to the base of Oligocene, falls at the level ca. 0.5 m below the facial change corresponding to the large-scale sea-level fall and, thus, slightly precedes the accumulation of low-calcareous oil-bearing Oligocene-lower Miocene Maikop Fm. The prominent positive δ13C and δ18O excursions occur at the base of this formation.

The study of the characteristics and dynamics of laboratory biomarkers in patients with cardiovascular diseases (CVD) with type 2 diabetes mellitus who underwent COVID-19-associated pneumonia is of great clinical importance for preventing the risk of adverse events. IN the study we used data from 65 patients in the present work. Patients were divided into 2 groups: group 1 included patients with CVD: arterial hypertension (AH) in combination with coronary artery disease (CAD) without DM2 (n=45), group 2 included patients with CVD and DM2 (n=20). Patients were examined at baseline in the infectious disease hospital and 3 months after discharge. During laboratory examination of blood biosamples we evaluated parameters of general blood test; biochemical and immunologicai parameters; elastic properties of the vascular wall. The analyzed leukocyte parameters and their index coefficients - increase in NLR ratio (neutrophils/lymphocytes) and decrease in LYM/CRP ratio (lymphocytes/CRP) were more significantly changed in DM2 group. Patients in both groups had a significant excess of baseline max CRP concentrations with decrease in parameters after 3 months, but with persistent excess values in group 2. Three months after discharge patients with DM2 had levels of hs-CRP, IL-1β and TNFa and NT-proBNP, that exceeded both the reference values and those in group 1, which reflected the presence of more pronounced vascular inflammatory potential for possible adverse events in this group of patients in post-COVID period. The method of multiple regression showed that DM2 is an independent risk factor for increased stiffness of the vascular wall. Thus, dynamic control of laboratory parameters has prognostic value in assessing the nature of the course of COVID-19 associated pneumonia in patients with CVD and DM2 developing an algorithm for personalized monitoring of patients in the post-COVID period with the aim of timely prevention of unwanted vascular complications.

The study of the characteristics and dynamics of laboratory biomarkers in patients with cardiovascular diseases (CVD) undergoing COVID-19-associated pneumonia may be of great clinical importance. The study included 116 patients who underwent COVID-19-associated pneumonia. The patients were divided into 2 groups. The first group included 49 patients without CVD, the second group - 67 patients with CVD. A blood sample was performed in all patients at the time of hospitalization and 3 months after discharge from the hospital. The parameters of general blood count, biochemistry, hemostasis, and biomarkers of inflammation were assessed - concentration of C-reactive protein (CRP), highly sensitive CRP (hs-CRP), homocysteine and IL-6. All patients initially underwent computed tomography of the chest organs. We found that ESR, WBC (leukocytes), NLR (neutrophils/lymphocytes ratio), fibrinogen, LDH (lactate dehydrogenase), LYM/CRP ratio (lymphocytes/CRP) were parameters that significantly distinguished patients in the 1st and 2nd groups. Three months after discharge from the hospital in patients of both groups the increased indicators approached the reference values, however, some parameters such as CRP, ESR, WBC, fibrinogen remained at a higher level in group 2 compared to group 1. Correlation analysis revealed the relationship between parameters of inflammation and hemostasis in the 2nd group of patients, which confirms the presence of latent vascular inflammatory potential in this group. It was revealed that such indicators as lymphocytes, neutrophils, APTT and LDH were associated with the initial volume of lung lesion more than 50%. Increase of these parameters by 1 unit contributes to increase in the volume of lung tissue damage by 6.5%, 6.4%, 11%, and 0.6%, respectively. Thus, dynamic control of laboratory parameters has prognostic value in assessing the nature of the course of COVID-19 associated pneumonia in patients with CVD and developing an algorithm for personalized monitoring of patients in the post-COVID period with the aim of timely correction of therapy to prevent unwanted vascular complications.

The study of the features and dynamics of the erythrocyte parameters of general blood analysis in patients with cardiovascular diseases who underwent SARS-CoV-2 associated pneumonia is of great practical importance. That was a prospective study. The study included 106 patients with SARS-CoV-2-associated pneumonia. All patients were divided into 2 groups. The first group included 51 patients without CVD, the second group included 55 patients with CVD .Patients in both groups underwent laboratory examination of blood samples at the time of hospitalization and 3 months after discharge from the hospital. Parameters of the erythroid series of the general blood test were assessed. Among inflammatory biomarkers, we examined the concentration of C-reactive protein (CRP), high-sensitivity CRP (hs-CRP) and homocysteine. Initially all patients underwent computed tomography of the chest organs. Revealed what indicators of the erythroid series in the groups of patients with and without CVD had significant differences in a number of parameters: ESR; RDW-SD and RDW-CV with significant excess of parameters in group 2. Three months after discharge from the hospital, patients in both groups had a significant increase in HCT, MCV, MCH. There was detected decrease in both groups in MCHC, RDW-CV (p<0.001 for all parameters), ESR level in group 2.At baseline, CRP exceeded reference values in both groups of patients, reaching maximum values in group 2. After 3 months CRP decreased significantly only in group 1. Increased CRP was associated with elevated hs-CRP in 3 months after discharge and elevated homocysteine levels in both groups, indicating the persistence of prolonged inflammatory vascular reaction in patients after SARS-CoV-2 associated pneumonia, more pronounced in group 2 patients. RDW-CV over 13.6 and lymphocytes / CRP less than 0.6 increase the likelihood of having lung tissue damage over 50% by 9.3 and 5.9 times, respectively. Thus, the data obtained confirm that RDW-CV, the coefficient of variation of erythrocyte distribution width, associated with the parameters of inflammatory response and the lymphocytes / CRP is lung volume marker and of COVID-19 severity. Careful consideration of already known laboratory parameters allows us to expand the number of indicators influencing the risk of COVID-19 complications and enable an earlier response to a difficult situation.

The comparative characteristics of sedimentary successions corresponding to the paleoecological event OAE 2, which are spaced over 1000 km apart within the Crimean–Caucasian region, are present. It is shown that the sediments accumulated during this time span under different sedimentary conditions are featured by the similar structures. The sedimentological, geochemical, and paleoecological analyses, indicate that (1) stable oxygen deficient conditions were not spread in the water column of the paleobasin; they occurred locally in a thin layer of bottom water owing to the oxidation of organic matter accumulated on the seafloor; (2) geochemical anomalies inherent in the TOC-rich horizon extend to the embedding layers that indicate their involving to the paleoecological event. The carbonaceous sediments of OAE 2 formed due to the enhanced nutrients influx from the land during the eustatic transgression caused the dramatic increase in the plankton productivity. The transgression was complicated by frequent sea-level fluctuations of minor magnitude associated with the Milankovitch precession cycles.

Abstract Funding Acknowledgements Type of funding sources: Public Institution(s). Main funding source(s): Tyumen Cardiology Research Center, Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia Objective To study the role of therapeutic exercises (TE) in the correction of blood pressure, stiffness of the vascular wall, metabolic indices of body structure (volume, mass, area of visceral fat) and bone mineral metabolism in postmenopausal hypertensive patients. Methods. The study included 138 patients (mean age was 58.32 ± 7.61 years). All patients are divided into 3 groups. The first control group is 20 women without arterial hypertension and menopausе. The second group consisted of 58 patients with arterial hypertension (AH) and postmenopause who was not undergone complex of TE and the 3rd group - 60 women with AH and postmenopause who was undergone TE complex. Patients of all groups were examined in dynamics: at the starting point of the study and in 12 months after, ambulatory monitoring of blood pressure; sphygmography; densitometry and test for serum biochemistry parameters of blood samples, including sex hormones, vitamin D. Results. In the course of the study, blood pressure, vascular wall stiffness parameters, metabolic indices of body structure and disorder parameters of bone mineral metabolism were comparable in group 2 and 3 against the background of significantly reduced levels of sex hormones. Multidirectional correlation relationships between the studied parameters are revealed. The basic therapy in combination with therapeutic exercises led to a significant decrease in blood pressure and metabolic indices of body structure (p<.001) and to a persistent tendency of decrease the pulse wave velocity and increase of bone mineral metabolism in gr.3. Conclusion. The result of the study indicates that the exercise therapy complex used in the form of regular classes can be recommended for implementation in clinical practice with the aim of comprehensively affecting the patient’s body and developing personalized treatment tactics for postmenopausal women with hypertension.

A relatively complete section of the Maikop Group (Oligocene – lower Miocene) is exposed along the Sulak River valley in Dagestan (NE Caucasus) and contains a depositional record for this part of the Eastern Paratethys. At the Sulak River outcrop, the Maikop Group is ca. 1200 m thick and can be divided into six lithologically‐defined formations: these are from the base up the Khadum Formation (Rupelian), the Miatly Formation, the Lower Clayey Formation, the Mutsidakal Formation (Chattian), the Riki Formation and the Zuramakent Formation (lower Miocene). The Khadum Formation rests on the upper Eocene Belaya Glina Formation and the boundary is marked by a sharp lithological transition from pale‐coloured, bioturbated limestones below to black organic‐rich shales above.Biostratigraphic studies of calcareous nannoplankton in samples from the Sulak River section allowed the position of the Eocene – Oligocene boundary at the base of the Maikop Group to be defined. The boundary occurs within the CP16 Zone near the division between the CP16a and CP16b subzones. This is consistent with the age of the boundary at a reference outcrop along the Kheu River in Kabardino‐Balkaria in the Central North Caucasus, some 200 km west of Dagestan. A positive oxygen stable isotope anomaly occurs at the top of the Belaya Glina Formation.Samples of the Maikop Group are characterized by variations in TOC content ranging between 0.14 and 11.06 wt. %. The highest values were measured in both carbonate‐ and clay‐rich samples from the Khadum Formation, and the lowest (less than 0.5 wt.%) in sandstones from the overlying Oligocene Miatly, Lower Clayey and Mutsidacal Formations. Samples of the lower Miocene Riki and Zuramakent Formations have moderate TOC values (on average more than 1.5 wt.%). Results of Rock‐Eval pyrolysis show that Maikop samples contain kerogen Types II and III which is distributed unevenly throughout the formations. Clay‐rich rocks in the upper part of the Khadum Formation (Solenovian Member) with Type II kerogen have the greatest oil‐generating potential, with initial hydrogen index values estimated at 400‐600 mg HC/g TOC. The Miatly Formation sandstones and siltstones contain migrated bitumen which is recognized from increased values of Rock‐Eval S1 and the high Production Index (S1/(S1+S2). Overlying Oligocene – lower Miocene rocks contain mainly Type III kerogen, although increased TOC values obtained from samples of the Riki Formation indicate that it may have minor gas source potential.Samples of Maikop Group sediments from the Sulak section were analysed for their contents of Mo, S, Fe, Mn, V, Ni and other elements. A stagnation coefficient (Mo/Mn x 100) was calculated and was interpreted as a measure of the intensity of anoxia in the Maikop palaeobasin. Anoxic conditions are interpreted to have reached a maximum in the Rupelian and Aquitanian during deposition of the Khadum and Riki Formations respectively. However, geochemical conditions were unstable and the oxygen concentration in the bottom waters varied widely over time. Thus, the Zuramakent Formation at the top of the Maikop Group was largely deposited in normally oxygenated conditions.

The Urtsadzor section, typical for the Paleocene-Eocene of Southern Armenia, is composed of hemipelagic to shelf succession. Planktonic foraminifera (PE), larger benthic foraminifera (LBF), and nannofossils were studied from Priabonian sediments of Urtsadzor section that enabled direct correlation of the biohorizons of these three groups. We present here the results of the microfossil study from the Bartonian and Priabonian parts of the section, with a special focus on larger and smaller benthic foraminifera (SBF). The 350 m thick studied interval corresponds to the planktonic foraminiferal zones P12/E10-11 to P15/E15, the nannofossil zones NP16 to NP19, the LBF zones SBZ17 to SBZ19, the SBF zones Heterolepa eocaena Cibicidoides landjaricum, Cibicidoides truncanus, Planulina costata. The SBZ17 zone is characterized by the lowest and highest occurrences (LO and HO) of Nummulites ptukhiani and corresponds to P12 and NP16-17/CNE14-15 zones. The upper boundary of SBZ17 and that of the SBZ18A/B subzones are missing. The SBZ18C subzone, identified by the LO of Heterostegina reticulata multifida accompanied by the LOs of Pellatispira,Biplanispira, and Nummulites hormoensis, lies within P15/E14 and NP18-19 zones. The LBF is represented by 40 species of nummulitids, orthophragminids, pellatispirids, as well as Silvestriella, Fabiania, Chapmanina, and Sphaerogypsina. The SBF assemblages contain more than 50 species. The transition from SBZ18 to SBZ19 in the studied section includes the following bioevents: 1. The highest common occurrence of N. maximus, HO of D. discus, and LOs of D. pratti minor, A. alpina, and Silvestriella; 2. The lowermost rare occurrence of Spiroclypeus, LO of H. reticulata mossanensis; 3. The lowermost common occurrence of N. fabianii and Spiroclypeus. The Bartonian-Priabonian boundary in this section, defined by the LO of Chiasmolithus oamaruensis, falls to the lower part of P14 and E14 zones, Cibicidoides truncanus zone of SBF, and between SBZ17 and 18C zones of LBF.

The lower Eocene sediments from the classical Paleogene section exposed along the Kheu River, northern Caucasus, southern Russia are here studied. This ca. 50m thick succession is lithologically contrasting: the lower and upper parts are composed by soft marls separated by a thick Radiolaria-rich unit of non-calcareous and low-calcareous mudstones with intercalations of compact cherty layers. According to nannofossil and dinocyst biostratigraphy, the unique intercalation of Total Organic Carbon (TOC)-rich sediment (sapropelitic bed) in the lower part of the lower Eocene correspond to the Paleocene-Eocene Thermal Maximum (PETM) and a series of sapropelitic interlayers in the upper marly part of the lower Eocene succession correlates with the Early Eocene Climatic Optimum (EECO). The study of nannofossil and dinocyst assemblages enabled detailed zonal subdivision and first-order calibration of nannofossil and dinocyst bio-events during this time-span. The studied interval of the section embraces the complete succession of nannofossil zones NP9-NP13 of Martini, 1971, CP8-CP11 of Okada and Bukry, 1980 and CNP11-CNE5 of Agnini et al., 2014. By means of dinocyst stratigraphy, the succession of Apectodinium hyperacanthum, Axiodinium augustum, Deflandrea oebisfeldensis, Dracodinium astra, Stenodinium meckelfeldense, Dracodinium varielongitudum, Ochetodinium romanum/Samlandia chlamydophora and Areosphaeridium diktyoplokum zones are identified in the Ypresian part of the Kheu section.

Представлены результаты палинологического изучения средне-верхнеэоценовых отложений опорного разреза Актумсук (плато Устюрт, Узбекистан), сопоставленные с данными изучения известкового наннопланктона. Изучение распространения диноцист в разрезе выявило 5 диноцистовых зон шкалы Пери-Тетиса: Costacysta bucina, Enneadocysta pectiniformis, Rhombodinium draco, Rhombodinium perforatum, Thalassiphora reticulata. Прямое сопоставление с зонами известкового наннопланктона позволило уточнить уровни появлений ключевых видов диноцист. На основе данных изучения диноцист и наннопланктона установлены два существенных стратиграфических перерыва внутри разреза, отвечающих верхнему ипру и верхней части бартона–низам приабона. Анализ количественных флуктуаций различных групп палиноморф по разрезу свидетельствует об изменениях в обстановках осадконакопления этой части бассейна Пери-Тетиса в лютете–приабоне: в начале лютета начался существенный трансгрессивный этап; в середине лютета произошло относительное углубление бассейна; после перерыва в осадконакоплении в конце бартона–начале приабона осадконакопление вновь происходило в открытоморской внешней неритической обстановке.

The results of integrated study of the Cretaceous/Paleogene transition in the northeastern Caucasus are reported. The lithological, geochemical and micropaleontological characteristics of the sediments from two sections (Okhli and Gubden, Mountainous Dagestan) accumulated in different parts of paleobasin are displayed. An analysis of nannofossil distribution at the Cretaceous/Paleogene transition allowed to define the stratigraphic position of the stage boundary and reveal the interval of sediments (1–2 m thick transitional zone) accumulated under stress conditions. The large-scale sea-level fall occurred at the onset of the Cretaceous/Paleogene boundary event is evidenced. It led to the erosion and redeposition of the Maastrichtian calcareous sediments. In Okhli section, the occurrence of palygorskite is detected in the clay mineral assemblage of the transitional zone. The local concentrations of coprolites (Decapoda?) and spherical nodules of different composition (more likely, concretions) are found in the clay layer onlapping the erosional surface at the top of Maastrichtian. There is no reliable evidence of the impact nature of these nodules. The lithological record at the Cretaceous/Paleogene transition of the studied sections is similar to those exposed in other areas of the NE Peri-Tethys (e.g., southern Turkmenistan and Mangyshlak Peninsula).

В статье изложены результаты комплексного исследования отложений, приуроченных к границе мела и палеогена на Северо-Восточном Кавказе. Изучены два разреза — Охли и Губден (Горный Дагестан), вскрывающих толщи, которые накапливались в различных зонах палеобассейна; приведена их литолого-геохимическая характеристика. Анализ распределения в пограничных отложениях наннопланктона позволил уточнить положение границы мела и палеогена и выявить интервал отложений (переходная зона 1–2.5 м), накопление которых происходило в палеоэкологически неблагоприятных для биоты стрессовых обстановках. Установлены свидетельства значительного по амплитуде падения уровня моря в начале мел/палеогенового события, что привело к локальному размыву и переотложению маастрихтских карбонатных пород. В разрезе Охли в ассоциации глинистых минералов из переходной зоны установлено присутствие палыгорскита; здесь же в глинистом слое, залегающем на эрозионной кровле маастрихтских известняков, найдены локальные скопления копролитов (Decapoda?), а также округлые включения разного состава, которые, по-видимому, являются микроконкрециями. Убедительные свидетельства их импактной природы отсутствуют. Изученные разрезы, вскрывающие отложения мел/палеогенового события, имеют сходство с другими изученными разрезами этого события на смежной территории Северо-Восточного Перитетиса — в Южном Туркменистане и на полуострове Мангышлак.

Manifestations of short-term global and subglobal events have been recognized in the Mesozoic and Cenozoic sedimentary record of the North Caucasus: Paleocene/Eocene boundary PETM, late Cenomanian (OAE2), late Albian (OAE1c and OAE1d), terminal Aptian–early Albian (OAE1b), early Aptian (OAE1a), late Hauterivian (Faraoni), late Valanginian (Weissert), early Toarcian, late Pliensbachian, and others. The similarities and differences of their sedimentological, geochemical, and paleoecological characteristics were revealed during complex studies. Some events are characterized by both negative and positive carbon and oxygen isotopic anomalies. It was shown that most part of the paleoecological events occurred during the sharp sea-level fluctuations and was frequently accompanied by the accumulation of sediments variably enriched in organic matter (OM). The events were characterized by different-scale turnovers in the microbiota composition. Changes in microfossil assemblages allowed us to estimate the degree of perturbation of the trophic level of basins in response to the terrestrial influx of nutrients during marine transgression.

— The results of palynological study of the mid-upper Eocene sediments of the Aktumsuk key-section (Ustyurt Plateau, Uzbekistan), calibrated with nannoplankton data, are presented. Dinocyst stratigraphical distribution permitted to recognize five Dinoflagellate Zones from the Peri-Tethys zonation: Costacysta bucina, Enneadocysta pectiniformis, Rhombodinium draco, Rhombodinium perforatum, and Thalassiphora reticulata. First-order calibration with nannoplankton zones permitted to precise the lowermost occurrences of the key dinocyst species. Based on the dinocyst and nannoplankton data, two important stratigraphic hiatuses, corresponding to the upper Ypresian and upper Bartonian-lower Priabonian, were recognized. Analysis of quantitative fluctuations of different groups of palynomorphs through the section indicates paleoenvironmental changes in this part of the Peri-Tethys during the Lutetian-Priabonian: the beginning of significant transgressive phase in the early Lutetian, relative deepening in the mid Lutetian; after the break in sedimentation at the end of Bartianian-beginning of Priabonian the sedimentation continues again in the open-marine (outer neritic) environement.

The Cretaceous/Paleogene (K/T) boundary interval was studied in the Okhli and Gubden sections, northeastern Caucasus. Two sediment successions represented in these sections were accumulated in different zones of the paleobasin and distinguished by their lithological and geochemical characteristics. The high-resolution study of nannofossils revealed very gradual changes in nannoplankton community at the Cretaceous/Paleogene transition. The nannofossil assemblage becomes poor from the level ca. 4 m below K/T boundary and it is very scarce in the last 2.5 m of uppermost Maastrichtian. The significant sea-level fall is evidenced in the beginning of the K/T event. It led to erosion and redeposition of Maastrichtian calcareous sediments within the thin layer of clay, covering erosional surface in the Okhli section. The clay mineral assemblage, starting from this surface contains palygorskite. The concentrations of coprolites (Decapoda?) and microspherulas (diagenetic microconcretions) with higher content of some trace elements were found within the small red lenses at the base of the clay layer overlying the Maastrichtian erosional surface. The reliable evidence of impact event are not recognized. The evolutional trends which are recorded within the Cretaceous/Paleogene transitional interval in the Okhli and Gubden sections are similar to trends recognized in studied sections of the K/T event on the adjacent territories of the North-Eastern Peri-Tethys (e.g., southern Turkmenistan and Mangyshlak Peninsula).