The article is dedicated to Dina Markiianivna Pyatkova, a well-known scientist and researcher in the field of stratigraphy and paleontology, candidate of geological and mineralogical sciences, senior researcher of the department of stratigraphy and paleontology of Mesozoic sediments of the Institute of Geological Sciences of the National Academy of Sciences of Ukraine. The main facts from the biography of Dina Markiianivna Pyatkova, her research activities, main achievements and most important scientific publications are highlighted.

The paper discusses the scientific inheritance of Dr. Marharyta M. Permiakova who was a well-known scientist and expert in the field of paleontology and stratigraphy, Candidate of geological-mineralogical sciences, Senior Scientist of the Department of Stratigraphy and Paleontology of Mesozoic sediments (Institute of Geological Sciences, NAS of Ukraine), whose research between 1963 and 2002 was focused on ostracods from Jurassic sediments of Dnieper-Donets Depression, north-western areas of Donbas and Crimea. This paper provides a short overview of the paleontological collections of Dr. Marharyta M. Permiakova which are stored at the Department of Stratigraphy and Paleontology of Mesozoic sediments (IGS, NAS of Ukraine), and also, her scientific achievements reflected in more than 45 scientific publications which include three coauthored monographs, articles, and several research and contract reports. A digitalized database of these paleontological dataset has been generated. Dr. Marharyta M. Permiakova developed and co-authored various regional and integrated stratigraphic schemes for the Jurassic of Ukraine based on ostracod biostratigraphy. This paper provides the scientific results of the Jurassic ostracod studies that were first undertaken by late Dr. Marharyta Permiakova in these areas, and also, the bibliography of her publications

Problem statement. Detail study of both vertical and spatial distribution of calcareous nannofossils from the Paleocene sediments of the Ukrainian Carpathians enabled to determine the evolutional development of Haptophyta algae during the Paleocene, and became the basis for correlation of boundary markers and correlative biohorizons. Here we summarize data obtained from previous research, and also our own, and propose an updad biozonation of Paleocene sediments of the Northern and Southern slopes of the Ukrainian Carpathians. Prerious work. Calcareous nannofossil research of the area goes back to the 1960's. These studies had a fragmentary character with only few sections examined for their nannofossil content. Materials and research methods. The paper includes the results of nannofossil research from numerous sections of Paleocene Flysch developed in the Outer and Inner Carpathian nappes. Discussion of the research data. The paper discusses the biozonation and correlation of local lithostratigraphic units of the Ukrainian Carpathians based on the detail study of nannofossils. For the first time, the complete successions of nannozones of the latest Geological Time Scale have been identified in the Ukrainian Carpathians. In the Outer (Flysch) Carpathians several nannozones were determined within the Skyba and Boryslav-Pokuttya nappes. There include - Markalius inversus / Biantholithus sparsus (NP1), Cruciplacolithus tenuis (NP2), Chiasmolithus danicus (NP3) and Ellipsolithus macellus (lower NP4) in the Upper Striy subsuite; top Ellipsolithus macellus (NP4), Fasciculithus tympaniformis (NP5), Heliolithus kleinpelli. ( NP6) in Yaremcha Formation, Discoaster mohleri (NP7) in Bytkiv layers, Heliolithus riedelii (NP8), Discoaster multiradiatus (bottom NP9) from the Yamna suite; Chiasmolithus danicus (NP3) from Upper Bereznyan subsuite of Dukla nappe; Fasciculithus tympaniformis (NP5) in Gnylets suite of Chornohora nappe and Markalius inversus (NP1) in Urdyn suite of Svydovets nappe. Within the Inner Carpathians nannozones were defined in the Lower Metova subsuite of the Vezhany nappe - Biantholithus sparsus (NP1), Fasciculithus tympaniformis (NP5), Heliolithus kleinpelli. (NP6), Heliolithus riedelii (NP8); Sushmanets suite of Monastyrets nappe contained Fasciculithus tympaniformis (NP5), Heliolithus kleinpelli. (NP6) and Tribrachiatus contortus (NP10) of the Early Ypresian. The stratigraphic positioning of nannofossil assemblages was rectified and their correlation with foraminifera and dinocyst zones was demonstrated. These nannozone assemblages from the Ukrainian Carpathians are correlated with the Danian, Selandian and Thanetian stages of the Geological Time Scale (GTS, 2012 and 2016). This integrated research enables to rectify and modify the stratigraphic scheme of the Paleogene from the Carpathian region. Conclusions. A modern calcareous nannofossil biozonation of the latest International schemes has been recognized from the studied Paleocene sections of the Ukrainian Carpathians. Nine (9) nannozones ranging from NP1 (Early Danian) to NP9 (Late Thanetian - Early Ypresian) and also the lowest NP10 nannozone of Early Ypresian have been identified in strata from different structural-tectonic units. The nannofossil biozonation is correlated with those foraminifera and dinocyst biochronology. The age and correlation for the Paleocene stratigraphic subdivisions has been justified based on the nannofossil bio-stratigraphy. This resulted in the upgrading of the existing stratigraphic scheme of the Paleogene of the Ukrainian Carpathians.

Summary An analysis of the geological structure of the Cenozoic formation complex of the Carpathian-Black Sea segment of Tethys by event-stratigraphic criteria has been worked out. The geomorphological, structural-tectonic, geodynamic, eustatic, climatic, biotic, paleoecological, lithological, sedimentological and seismostratigraphic regulatory factors of influence on the geological structure of different tectonic and geodynamic blocks are characterized. Systematic analyses has identified the processes and events (historical-geological phases of Earth expansion and compression, impact, anoxic, etc.) that are recorded in the different stratons and transitional boundary layers of the Cenozoic deposits and formed the modern geological structure of the study regions. Stratigraphic models and charts of Cenozoic deposits of the Western (Carpathian) and Southern (Black Sea, Crimea, Azov-Black Sea) regions were developed. The different facial systems of the corresponding spatio-temporal levels are identified, the rock-layered complexes, the material composition and the structure of the stratons of the corresponding genesis are determined. Morphostructural, bio-, lithofacial, geodynamic, sedimentological, cyclostratigraphic, volcanic criteria are considered. Processes of the offshore landslides, currents, turbidites are analyzed. The influence of hydrology factors (fluctuations of the sea level and annual runoff) is investigated.

Summary The structure of the Carpathians geosystem contains information on the litho-facial, sedimentological, geodynamic, tectonic, paleogeographic history of the region development and those processes that took place during the Meso-Cenozoic. The main factors in the formation of shift-hazardous zones are related to the processes of geological reorganization in Early and Late Cretaceous, on the boundary of the Cretaceous and Paleogene, in Paleocene, Eocene, Oligocene and Neogene. Olisthostromes, mudflows, and landslides widely developed at the different stratigraphic levels. Considering diversity of the processes that led to the formation of the modern landscape, including shift-hazardous zones, a comprehensive systemic analysis was carried out. The stratigraphy serves as a basis for detection of landslide hazardous zones. Analysis of the events and processes is a key for determining the event-stratigraphic criteria of geological evolution.

New data concerning the spatial-temporal distribution of nannofossils in the Metova Formation of the Southern slope of the Ukrainian Carpathians are discussed. The nannozones Biantholithus sparsus-NР1 (Early Danian), Fasciculithus tympaniformis-NP5 (Selandian), Heliolithus kleinpellii-NP6 (Late Selandian), Heliolithus riedellii-NP8 (Thanetian) were recognized in the Lower Metova Subformation. The scope, boundaries and Paleocene age of the lower part of the Metova Formation of the sections in the basins of the Tereblya, Velyka and Mala Uholka rivers (Transcarpathians) have been substantiated. As a result, the stratigraphy and geological structure of the Vezhana nappe (Marmarozh rocks) of the Ukrainian Carpathians was clarified.

The article describes the history of nannofossil research of the Paleogene sediments in Ukraine from the beginning of the end of the XIX century. All available data concerning the significance of this ortho-stratigraphic group for detailed stratification purposes of diverse regional subdivisions and their correlation with International Stratigraphic Chart based on nannofossil biostratigraphy has also been discussed.

In Ukraine, the perspective oil and gas bearing regions are located within the Carpathian-Black Sea segment of the Tethys, and the southern slopes of the East European Platform. We examined the plankton microfossil content from numerous Paleogene samples obtained from outcrop and exploration borehole sections. The interpretation of the large dataset concerning the spatial-temporal distribution of Foraminifera, Calcareous nannofossils and Dinocysts is provided. The characteristics of the stratigraphic distribution of planktonic fossil assemblages in the Paleogene sections, their cyclicity in the formations and the specifics of the zonal subdivision based on the defined correlation levels are given. As a result of an integrated study the biozonal subdivision of Paleogene sediments of Ukraine is substantiated, and an interregional correlation of various facies of the Paleogene sections with the International Stratigraphic Scheme is undertaken.

Unconformities – are surfaces that act as important stratigraphical and geological boundaries, and are widely applied during geological mapping, Seismic and Sequence stratigraphic analysis in defining the limits of depositional sequences. They represent the geological time of non-deposition and/or erosion, and have wide geographical distributions. The other major value of unconformities is their possible role in hydrocarbon entrapment, migration and reservoir property controls. They are easily tracked and selected by the means of 2D and 3D seismic data and wellbore logging interpretations. Their identification becomes even easier and precise, if the data is integrated with the results of microfossil biostratigraphy.This paper highlights the results of detailed Paleocene - Eocene calcareous nannofossil biostratigraphy of a vast Northern Peritethys area that enabled to recognize seven (7) levels of unconformities and breaks in sedimentation, and define their durations based on the missing intervals of standard biozones. The identified unconformities were grouped into age levels: 1 level: (Danian unconformity or Cretaceous - Paleogene), 2 level (Pre-Thanetian unconformity), 3 level (Thanetian), 4 level (Early Ypresian), 5 level (Middle-Late Ypresian), 6 level (Late Lutetian) and 7 level (Priabonian).Among them two levels have a regional and global importance (1 level – Danian and IV level – Paleocene- Eocene), while the rest are characterized by local distribution (5 level – Middle-Late Ypresian and 6 level – Late Lutetian). The 7-th level (Priabonian) can be related with the initiation of the post-Eocene unconformity that has a worldwide importance, since it is responsible for the generation of huge hydrocarbon accumulations in California, Northern Andes, Caucasus, northern Andes and other basins. Each unconformity is presented by a hiatus in the stratigraphic sequence of the section, the value of which is used to measure the amplitude of the break. Detailed Paleogene nannofossil biostratigraphic charts calibrated with the geomagnetic polarity chart enable precise determination of unconformity duration. Sedimentation rate diagrams were constructed for some studied sections (NW Black Sea shelf and Crimea peninsula sections). Calcareous nannofossil biostratigraphy was used to compile the correlation charts to determine the volume, age and geographical extent of each selected unconformity level. Their stratigraphic position was compared with the Global eustatic curve of the sea level of Haq et al. (1987) on which most of the selected unconformities coincide with the curve’s eustatic lows, e.g. levels 1, 3, 5 and 7 suggesting that long-term tectonic (plate tectonics) and shorter time climatic processes might have been responsible for their generation. Genetically, the unconformity levels belong to various types. Following the classification of Baraboshkin et al. (2002), the1-st (Danian) and 2-nd (Pre-Thanetian) unconformity levels belong to hardground type. 3-rd level (Thanetian) is a concealed or condensed type. 4-th level (Early Ypresian) is a subaquatic postdiagenetic erosional type. 5-th level (Middle-Late Ypresian unconformity) characterizes the nondeposition or erosional type of unconformity. The 6-th level (Late Lutetian) is considered as a disconformity (a diastema), while the 7-th level (Priabonian unconformity) is related with a eustatic sea level drop probably belonging either to the subaquatic postdiagenetic erosional or nondeposition type of unconformity.Paleogeographical maps of the area constructed for these time intervals indicate that the selected unconformities were developed in subaqueous conditions and were not associated with the development of continental weathering crusts (residuums).According to their duration, the unconformities (sedimentary breaks) are subdivided into two groups: long-term (more than 1 million years: Danian, Pre-Thanetian, Early Ypresian, Middle Ypresian, and partlly, Priabonian) and short-term (less than 1 million years - Thanetian, Late Lutetian, and at places Priabonian). The selected unconformity levels and their correlative surfaces (breaks in sedimentation) serve as limit boundaries for depositional sequences (sequences) that are relatively conformable successions of genetically related strata. Six (6) such sequences have been recognized from the correlation charts. These include (from bottom to top): Sequence I – limited by 1-st and 2-nd unconformity levels, and includes strata of the lower Belokamian suite of Crimea, lower Kuzbakian/ Tassaian suites of Eastern Pre-Caspian region and Sumbarsk formation of Southern Turkmenistan; Sequence IIa – bounded by 2-nd and 3-rd unconformity levels and includes lower Kachian formation of Crimea and partially Gromov and Lazurna suites of the NW Black Sea shelf; Sequence IIb – bounded by 3-rd and 4-th unconformity levels and includes upper part strata of the Kachian formation, tentatively the upper portion of the Lazurna suite of the NW Black Sea shelf; Sequence IIIa - bounded by 4-th and 5-th unconformity levels and include strata of Bakhchisaray formation of North Black Sea depression; Sequence IIIb – bounded by 5-th and 7-th unconformity levels and include thick strata of the Simferopolian, Kuberlinian, Kerestinian, Kumian and Almian formations of North Black Sea and Fore-Caspian depressions, Mechetkinian, Elshanian, Aksaisk formations of Fore-Volga uplift, and finally, Sequence IV is bounded by the 7-th unconformity level at the bottom and includes strata of Almian formation of North Black Sea depression, Balyklei and Beloglina formations of Fore-Volga uplift and Fore-Caspian depression. Within the Crimea-Caucasian region the interval between sequence IIIb and IV can be further subdivided into more detail units (parasequences) by the selection of the very short-lived 6-th level of unconformity (Late Lutetian).Despite different conclusions been widely reported on the effect of unconformities on their either enhancing or reducing role of reservoir properties (porosity, permeability, diagenetic changes, copartmentalisation, etc.), we believe that they are important and the obtained results can serve as reliable indications for successful exploration of hydrocarbon traps and probable migration pathways (along the unconformities surfaces) in Paleogene reservoirs of the Northern Peritethys. Calibration of these biostratigraphy results with additional seismic and wellbore data can help in understanding the subsurface behavior of these surfaces and reconstruct the tectonic and sedimentation history of the basins.

The paper presents the results of a paleoenvironmental analysis of calcareous nannofossils from Paleocene deposits of some areas of Tajikistan, Egypt, Ukrainian Carpathians, and the NW shelf of the Black Sea. The results of the study allow reconstruction of the paleobionomic conditions of the Paleocene basins. It was found that in the Paleocene period most of the study area was characterized by warm (tropical and subtropical) conditions.