In this paper the results of magnetostratigraphic studies of the Upper Cretaceous of the Central part of the Western Siberia penetrated by two wells - Severo-Tamarginskaya 59R and Zapadno-Igol'skaya 31P. Kuznetsovo and Gan'kino formations, Nizhneberezovo and Verchneberezovo subformations, dated by foraminifera were studied. The obtained biostratigraphic data show that the sediments formed in the Middle-Late Turonian-Early Maastrichtian time interval. The reported magnetostratigraphic sections is based on integrated paleomagnetic and biostratigraphic data from the two wells and comprises three magnetozones of reverse (R(1)K(2)km) and (R(2)K(2)mt) and normal (NK(2)t-st) polarity corresponding to the C34, C33r, C31r Chrons of the global magnetic polarity scale. The obtained data will be used compiled magnetic polarity scale of the Cretaceous of the Western Siberia. The resulting composite section will be one of the fragments of the regional magnetostratigraphic section (scale) of the Upper Cretaceous of the entire Western Siberia (it central part). This is its fundamental scientific and theoretical significance. From an applied practical point of view, this consolidated section already allows for correlation and dating of sedimentary deposits, and can be used to correct Regional stratigraphic Schemes of the Upper Cretaceous of Western Siberia, the layout of which is being actively discussed.

The article presents the results of paleomagnetic and magnetostratigraphic studies of the Upper Cretaceous of northeast of Western Siberia, opened by three wells: Kharampur 106P, Zapadno-Chaselka 1P and Novo-Chaselka 5P. According to the results of biostratigraphic studies, the studied sediments were formed in the Upper Cenomanian - Maastricht time interval. Based on complex (paleomagnetic and biostratigraphic) data obtained from three wells, magnetostratigraphic sections were constructed based on the synthesis of which a consolidated magnetostratigraphic section of the Upper Cretaceous of the Pur-Taz interfluve was first developed. This section consists of three magnetozones: one forward NK2(sn-st(2)) and two reverse (R(1)K(2)cp and R(2)K(2)m(1)) polarity, compared with the Ogg world scale of magnetic polarity. The resulting composite section will be one of the fragments of the regional magnetostratigraphic section (scale) of the Upper Cretaceous of the entire Western Siberia (its north, central part and south). This is its fundamental scientific and theoretical significance. From an applied practical point of view, this consolidated section already allows for correlation and dating of sedimentary deposits, and can be used to correct Regional stratigraphic Schemes of the Upper Cretaceous of Western Siberia, the layout of which is being actively discussed.

Upper Cretaceous magnetostratigraphy of northern West Siberia has been reconstructed using new paleomagnetic data from five wells in the Kharampur oil-gas-condensate field (1049, 109N, 106P-Yu, 105N, and 2073N). The scientific motivation of this investigation was to construct a composite Upper Cretaceous magnetostratigraphic section of the north of Western Siberia based on integrated paleomagnetic and biostratigraphic data, which represent a part of the Upper Cretaceous magnetic polarity scale of all Western Siberia. The study area is located within the Middle Pur trench in the Pur-Taz interfluve. Natural remanent magnetization in the samples of the Pokur, Dorozhkovo, Okhteurievka, Kuznetsovo, Lower Berezovo, and Upper Berezovo Formations was analyzed by stepwise alternated field (AF) and thermal demagnetization and used to compile the magnetostratigraphic sections of the five wells. Correlations among the well sections form a basis for a composite magnetostratigraphic record of Upper Cretaceous (Cenomanian through Campanian) strata in the area. The composite section comprises two normal polarity zones NK2(sn-st) and NK2cp and correlates with the regional Upper Cretaceous magnetostratigraphic section of southern West Siberia, as well as with the global polarity time scale.

—The post-Cenomanian sedimentary sequence of the East Messo-Yakha oil and gas field in the southern Gydan Peninsula comprises twelve lithological units (beds) correlated to Upper Cretaceous, Paleogene, and Quaternary regional stratigraphic stages and formations. The facies of the sedimentary units are constrained from lithology and microfossils. The stratigraphic division is based on bio-stratigraphy (fauna and spore-pollen assemblages), paleomagnetism, and geochronology (quartz and feldspar grains dated by optically stimulated luminescence). The deposition record is interrupted by six large stratigraphic unconformities. The obtained data provide new insights into the Late Cretaceous, Paleogene, and Quaternary paleogeography of the area.

Представлены результаты исследований надсеноманского комплекса отложений ВосточноМессояхского месторождения (юг Гыданского полуострова). Выделено двенадцать литологических пачек, сопоставленных с региональными стратиграфическими горизонтами и свитами верхнего мела, палеогена и четвертичной системы. Фациальная принадлежность стратонов обоснована результатами анализа их литологических характеристик (литофациального) и комплексов микрофауны (биофациального). Выполнены комплексные стратиграфические исследования: биостратиграфические (микрофаунистические и палинологические), магнитостратиграфические и датировки методом оптически стимулированной люминесценции зерен кварца и полевого шпата (ОСЛ). Установлено шесть крупных стратиграфических несогласий, дана оценка их длительности. Уточнены представления о палеогеографии севера Западной Сибири в позднемеловое, палеогеновое и четвертичное время.

—Magnetostratigraphic data from wells in southern West Siberia that strip the Upper Cretaceous and Cretaceous–Paleogene boundary strata in three areas (three wells in the Omsk Basin, two wells in the Bakchar Iron Basin, and two wells in the southern Kulunda Basin) are used to compile the respective regional magnetic-polarity scale. According to the available biostratigraphic constraints, the deposition spanned the period from Albian to Bartonian. The reported regional polarity scale is based on integrated paleomagnetic and biostratigraphic data from the seven wells and comprises four Upper Cretaceous zones of normal (NK1-2(al-st) and NK2mt) and reverse (RK2km and RK2mt) polarity corresponding to the C34, C33r, C31r, and C30n Chrons of the global magnetic polarity scale and four Paleogene zones of reverse polarity: R1E1zl, R2E1t, R1E2t-i(?), and R1E2l-b, with the first two correlating with the C26r and C25r Chrons. Some of the Upper Cretaceous magnetozones enclose thin intervals (microzones) of the opposite polarity. The regional Cretaceous–Paleogene magnetic-polarity scale of southern West Siberia reveals several deposition gaps from 6 to 28 Myr long. The magnetostratigraphic data can be used to determine deposition rates and can make reference for local, regional, and global correlations of geologic events given that polarity reversals are of global extent.

The study presents new paleomagnetic data on the Upper Cretaceous and Cretaceous Paleogene boundary intervals of the southern Kulunda basin (Alei area), which were obtained from core samples collected from a 305-m-thick section penetrated in two wells. The paleomagnetic sections of each well were compiled and correlated based on the characteristic remanent magnetization (ChRM). Paleomagnetic, geological, stratigraphic, and paleontological data were used to compile the Upper Cretaceous and Cretaceous Paleogene magnetostratigraphic section of the southern Kulunda basin. The magnetostratigraphic section consists of five magnetozones, one normal polarity zone, and four reversed polarity zones spanning the Upper Cretaceous and Lower Paleogene. The lower part of the Gan'kino Horizon, showing normal polarity, forms a single normal polarity magnetozone N. The upper part of the Gan'kino Horizon comprises two reversed polarity magnetozones (R(1)km and R(2)mt). The Talitsa and Lyulinvor Formations of Lower Paleogene age correspond to two reversed polarity magnetozones (R(1)zl and R(2)i). The compiled Upper Cretaceous and Lower Paleogene magnetostratigraphic section was correlated with the geomagnetic polarity time scale. Two options were considered for correlating the lower normal polarity part of the section with geomagnetic polarity time scale of Gradstein. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

New micropaleontological and paleomagnetic data were obtained by studying core samples of Cenozoic continental deposits from two boreholes drilled in the south of Tyumen oblast (Western Siberia). Palynological assemblages in deposits of the Tavda (upper part), Novomikhailovka, Turtas, Abrosimovka, Tobolsk, Smirnovka, and Suzgun formations were described. Deposits of these formations are enriched in spore-pollen assemblages, which can be correlated with assemblages of regional palynozones of the West Siberian Plain. Ostracods were described in Quaternary deposits. On the basis of biostratigraphic and paleomagnetic data, the Late Eocene (Priabonian)–Holocene age of deposits was substantiated. For the first time, beds with dinocysts of genus Pseudokomewuia were identified in deposits of the Turtas Formation (Upper Oligocene) of the Ishim lithofacial area. In total, nine regional magnetozones were distinguished in the paleomagnetic section. On the basis of palynological and paleomagnetic data, sections of two boreholes were correlated, and hiatuses in sedimentation were revealed. A large hiatus is at the Eocene-Oligocene boundary (Western Siberia): the Lower Oligocene Atlym Horizon and Miocene–Pliocene and Eopleistocene sediments are missing. The Oligocene interval of the section is represented in a reduced volume.

This study reviews a possible new position of the base of the Quaternary in West Siberia based on paleobotanical and paleomagnetic data in view of ratification of ICS recommendations by the IUGS Executive Committee and the decision of the Interdepartmental Commission on the Quaternary Stratigraphy of Russia to lower the base of the Quaternary (and, therefore, the base of the Pleistocene) at 2.58 Ma. The paleobotanical and paleomagnetic data from two horizons on the West Siberian plain (Kulunda, attributed in part to the formerly Neogene Gelasian Stage, and Kochki, attributed to the Quaternary) were used to identify global cooling that occurred synchronously with a regional cooling phase determined at the base of the Gelasian at Monte San Nicola, Italy.

This paper presents palynological and paleomagnetic characteristics of three West Siberian horizons: Zhuravka (Upper Oligocene, Chattian), Abrosimovka, and Beshcheul (Lower-Middle Miocene, Aquitanian, Burdigalian, Langhian, and Serravallian). We consider the distribution of dinocysts of the genus Pseudokomewuia in the stratotype section of the Zhuravka Horizon (Zashchitino Village) and in the section of borehole 13 (Chelyuskintsev Village), which exposes the Turtas, Abrosimovka, and Beshcheul Formations. Similar compositions and structures of dinocyst assemblages and similar palynofloras in the Turtas and Abrosimovka Horizons, as well as the sedimentation environment and cyclic structure of lacustrine deposits, suggest that the Paleogene/Neogene boundary should be localized at the base of the Beshcheul Horizon. We propose to include the Abrosimovka Horizon into the Upper Oligocene (upper Chattian). The data are correlated with the regional paleomagnetic scale. These views should be reflected in a new regional stratigraphic chart for the Paleogene-Neogene deposits of the West Siberian Plain. (C) 2016, V.S. Sobolev IGM, Siberian Branch of the RAS. Published by Elsevier B.V. All rights reserved.

In this paper the results of magnetostratigraphic studies of the Upper Cretaceous penetrated by two wells (S-124 and S-114) drilled in the Tomsk structural-facies zone (Bakchar iron ore deposit) are presented. The obtained biostratigraphic data show that the sediments formed in the Campanian–Maastrichtian time interval. The high-temperature component of the remanent magnetization identified in the rocks allowed us to compile paleomagnetic columns for each well and correlate the columns, using paleontological data, with each other and with the general magnetostratigraphic and magnetochronological scales. In magnetostratigraphic sections of two wells, the Campanian reverse-polarity Slavgorod Formation (R(km)) with a normal-polarity horizon is correlated with Chron C33(r) (top) and C33(n) (bottom) of the Gradstein scale, and the Maastrichtian normal-polarity Gan’kino Formation with a thin reverse-polarity horizon (N(mt)) is correlated with Chron C30 of this scale.