Разрез майкопских отложений р. Белая выше г. Майкопа является характерным для Западного и Центрального Предкавказья, хорошо обнаженным и изученным и может рассматриваться в качестве типового для майкопской серии. В нем наблюдается непрерывный переход от подстилающих светлых мергелей белоглинской свиты к темным глинам в основании майкопской серии. В нижнеолигоценовой части серии почти непрерывно обнажена пшехская свита, прослеживаются несогласия в подошве и кровле полбинского пласта. Выше следуют нижняя бескарбонатная и верхняя известковистая подсвиты свиты Морозкиной балки, баталпашинская и нерасчлененная септариевая+зеленчукская свиты верхнего олигоцена. Приводится подробное литологическое описание разреза с основными данными по ископаемым группам, описан состав изученного микрофитопланктона и фауны: наннопланктона, планктонных и бентосных фораминифер, моллюсков, ихтиофауны, приведены результаты палеомагнитного изучения разреза. Исследование палинологии и диноцист из этой же серии образцов было проведено ранее. Приведена история изучения майкопской серии и ее свитное деление, обсуждаются возможности использования полученных данных для ее корреляции и восстановления условий осадконакопления.

The Eocene interval of the section in the Belaya River valley is continuously exposed and is represented (from the bottom up) by green clays of the Cherkessk Formation, the marl–clayey member of the Keresta Formation, bituminous marls of the Kuma Formation, and light intensely bioturbated marls of the Belaya Glina Formation. There are gradual transitions between formations without signs of hiatuses. Eocene deposits are characterized by rich assemblages of nannoplankton, planktonic and benthic foraminifers (PF, BF), and organic-walled phytoplankton. The shallower water facies are recorded in the composition of benthos and mollusks at the boundaries of formations. The data on these groups of fossils make it possible to trace an almost complete zonal characterization of nannoplankton, dinocysts and PF and to compare these subdivisions of the middle–upper Eocene and early Oligocene both with other reference sections of the Eastern Peri-Tethys and standard zones and stages of the international stratigraphic scale. The following zones are distinguished: the upper part of the Cherkessk Formation—nannoplankton (NP15) and Acarinina bullbrooki PF zones; the Keresta Formation—nannoplankton (NP15+NP16) and Hantkenina “alabamensis” PF zones; the Kuma Formation—the nannoplankton (NP16+NP17) zones, Hantkenina “alabamensis” (at the lower boundary of the formation) and Subbotina turсmenica PF zones (above basal part), and Areosphaeridium diktyoplokum–Rhombodinium porosum dinocyst zone; the Belaya Glina Formation—nannoplankton (NP18, NP19+NP20, NP21) zones, Turborotalia centralis–Globigerinatheka tropicalis PF zone, and Charlesdowniea clathrata angulosa dinocyst zone; the lower part of the Pshekha Formation—nannoplankton (NP21) zone, Globigerina officinalis PF zone, and Phtanoperidinium amoenum dinocyst zone. These data make it possible to clearly correlate the Belaya River section with the sections studied in detail in Ciscaucasia (Kheu, Kuban, and Gubs rivers) and to reconstruct the conditions of sedimentation.

The sedimentary succession along the Belaya River (North Caucasus) provides a record of middle Eocene to Miocene sediments. This time interval is well known for its important climatic transitions (e.g., Middle Eocene Climate Optimum (MECO) and Eocene-Oligocene Transition (EOT)), and changes in basin configuration from Peri-Tethys to Paratethys. The Belays section contains two intervals marked by oxygen-depleted sediments; the Eocene Kuma Formation of the Peri-Tethys and the Oligocene Maikop Group of the Paratethys. Both are considered important source rocks for hydrocarbon exploration in the Black Sea and Caspian Sea. We present integrated stratigraphic results of the Belaya River section using calcareous nannoplankton biostratigraphy, magnetostratigraphy and 40Ar/39Ar dating. Furthermore, we investigate the geochemical character of the sediments using X-ray fluorescence (XRF) and stable carbon and oxygen isotopes. A middle Eocene age for the lower part of the succession is established from nannoplankton biostratigraphy. The Kuma Formation is dated between 42.1 and 38.4 Ma based on the assumption of constant sediment accumulation rates. A negative oxygen isotope excursion in the middle part of the Kuma Formation could be related to the MECO (similar to 40 Ma). The onset of the Maikop Group is dated around the base of chron C13n at an age of similar to 33.7 Ma, close to the EoceneOligocene boundary. Based on geochemical results, we show that the Kuma Formation and Maikop Group correspond to two different episodes of intensified oceanic oxygen depletion in the succession. We hypothesise that oxygen-depletion as recorded in the Kuma Formation is linked to an increased nutrient input in the open marine Peri-Tethys due to widespread volcanism in the Neotethys subduction zone, while oxygen-depletion as recorded in the Maikop Group is linked to basin restriction caused by the eustatic sea-level fall straddling the Eocene - Oligocene boundary triggering stratified conditions in the semi-isolated Paratethys Sea.

The section of Maikop deposits on the Belaya River upstream of the town of Maikop is characteristic of Western and Central Ciscaucasia; it is well exposed and well-studied and can be considered as the type section of the Maikop Group. The section shows a continuous transition from the underlying white marl of the Belaya Glina Formation to dark clay lying at the base of the Maikop Group. The lower Oligocene part of the section exposes an almost uninterrupted outcrop of the Pshekha Formation and shows unconformities at the base and top of the Polbian Bed. These are overlain by the lower non-carbonate and upper carbonate subformations of the Morozkina Balka Formation and the Batalpashinsk and undivided Upper Oligocene Septarian + Zelenchuk formations. This paper contains a detailed lithological description of the section with a summary of its fossils. The composition of the studied microphytoplankton and animal remains, including nannoplankton, planktonic and benthic foraminifers, mollusks, and ichthyofauna is described and paleomagnetic study results are presented. The study of palynology and dinocysts from the same series of samples was previously completed. The history of the study of the Maikop Group and its subdivision into formations are discussed. This paper discusses the possibility of using the data for correlation and reconstruction of the depositional environment.

The section on the outskirts of the town of Kantemirovka is proposed to serve as a reference one for Paleogene deposits of the Voronezh region. Observing the requirements of the current Stratigraphic Code of Russia, it is suggested to introduce the Middle Eocene Sergeevka and Tishki formations, which were defined previously by V.P. Semenov as mappable lithostratigraphic units instead of the Kiev Formation (regional stage) in the Paleogene stratigraphic scale of Ukraine, into the regional Paleogene stratigraphic scale of the Voronezh anteclise. The structure of the Sergeevka Formation and hypostratotype of the Tishki Formation defined in this section are considered with the analysis of the distribution of nannofossils, foraminifers, and diatoms in corresponding deposits. Benthic and planktonic foraminifers are used for defining regional biostratigraphic units, which are correlated between each other, with zones of the standard stratigraphic nannofossil scale, and units of the Middle Eocene Kiev regional stage of northern Ukraine. The boundary between the formations under consideration is universally marked by the replacement of carbonate sediments by terrigenous‒siliceous facies, disappearance of calcareous fossils, and development of a new biota. These features allow the boundary between these formations to be conditionally correlated with that between the Keresta and Kuma regional stages of the North Caucasus region.

The stratigraphy of Paleocene-Eocene rocks based on assemblages of dinocysts, benthic and planktonic foraminifers, nannoplankton, diatoms, and nummulites was refined in the sedimentary sequence penetrated by borehole (BH) 13 in the Gremyach'e potassium salt deposit. The rocks were subdivided into local lithostratigraphic units with refined ages and more substantiated reference to the general and regional scales. In addition to formations of the Volga-Caspian region: Saratov, Kamyshin, Tsaritsyn, Mechetka and Elshanka, for the Paleogene of the southwestern Volgograd region there were used formations of neighbor regions as well: Eisk Formation (Paleocene) in the eastern Donetsk Basin and the Sergeevka, Tishki and Kas'yanovka formations (Middle and Upper Eocene) in the Voronezh Anteclise. The presence of the Oligocene in the section of the Maikop Group has been established for the first time. New biostratigraphic units based on dinocysts and foraminifers were suggested.

В осадочной толще Гремячинского месторождения калийных солей, пройденной скважиной 13, уточнена стратиграфия палеоцен-эоценовых отложений по комплексам диноцист, бентосных и планктонных фораминифер, наннопланктона, диатомовых водорослей и нуммулит. Отложения расчленены на местные литостратиграфические подразделения с уточнением возраста и более обоснованной привязкой к общей и региональной шкалам. Помимо свит Поволжско-Прикаспийского субрегиона: саратовской, камышинской, царицынской, мечеткинской и елшанской, для палеогена юго-запада Волгоградской области использованы свиты и соседних субрегионов: Восточного Донбасса – ейская свита (палеоцен) и Воронежской антеклизы – сергеевская, тишкинская и касьяновская свиты (средний и верхний эоцен). Впервые установлено присутствие в разрезе майкопской серии олигоцена. Предложены новые биостратиграфические подразделения по диноцистам и фораминиферам.

New data on different organic remains and biostratigraphy of the Paleocene-lowermost Eocene type section in the Indol structural-facies zone of the Indol-Kuban' depression of the Eastern Crimea are discussed. The section demonstrates a succession of different faunal types from the shallow-water accumulation zone of carbonates (the southwestern Crimea) to relatively deep-water zone of pelagic sedimentation (the northern Caucasus). According to distribution of planktonic foraminifers, the section is subdivided into Acarinina acarinata, Morozovella subbotinae (s.l.), Morozovella aragonensis, and Acarinina bullbrooki zones, the standard units of the Paleogene scale elaborated for southern regions of the former USSR. Discocyclins discovered from the Paleocene interval of the section characterize the SBZ3, SBZ10, and SBZ11 zones of the Tethyan zonation of larger foraminifers. Nannoplankton assemblages studied for the first time in this section correspond, entirely or partly, to those of Heliolithus kleinpelli (NP6), Heliolithus riedeli (NP8), Discoaster multiradiatus (NP9), Discoaster lodoensis (NP13) and Discoaster sublodoensis (NP14) zones. Smaller foraminifers allowed subdivision of the section into new Anomalina danica, Karreriella zolkaensis, Asterigerina bartoniana kaasschieteri, and Pseudogaudryina pseudonavarroana (with two subzones) local zones correlated with regional zones of this faunal group. transformations of the basin ecosystem and correlation with sections of neighboring regions are briefly discussed.