Geology

Kimmeridgian–Volgian ostracods of Samarskaya Luka: Paleoecological analysis and reflection of sedimentation conditions in rock magnetism

Authors: Savelieva Y. N., Guzhikov A. Y.

The analysis of the distribution of the Kimmeridgian–Volgian ostracods in the section near the village Valy made it possible to establish a sequence of eight communities, the change of which reflects changes in the ecological conditions in the basin. Changes in sea level fluctuations, the main physical and chemical parameters of the ostracod habitat – temperature, salinity of water, oxygen content in it, eutrophy and concentration of organic matter in sediment – are reconstructed. Information on the magnetic susceptibility and its increase after heating was obtained.

Genus Tremabolites Zittel, 1878 (Porifera, Hexactinellida)

Authors: Pervushov E. M.

Tremabolites sponges known among the Middle-Late Cretaceous beds in Europe are reliably identifiable due to the numerous openings against the background of the skeleton smooth upper surface. The ideas of the level of organization in these sponges and of the species characteristics are far from being univocal. The paper deals with the species diversity of Tremabolites common in the Coniacian – Santonian rocks from the Volga Region. Examples of regeneration and budding in the representatives of the group are presented.

Structural features of the lower Permian salt-bearing series and the character of salt-tectogenesis manifestations in the Caspian Depression. Paper II

Authors: Pisarenko Y. A., Goncharenko O. P., Pisarenko V. Y.

The article presents the analysis of the inner structure of the salt-bearing series within the Caspian Depression. Certain salt-bearing complexes of various ages, compositions and plastic properties are distinguished. Their structural relations and the features of salt-tectogenesis manifestation are evaluated. Up to the present no subsalt uplifts have been confirmed in the Russian sector of the Caspian Depression and no HC fields have been discovered.

Influence of zeolitization on the migration of reservoir fluids on the example of jurassic and neocomian deposits (Yamal oil and gas region)

Authors: Osipova E. P., Astarkina A. G., Astarkin S. V., Strelnikov D. A., Reshetnikov M. V.

To assess the influence of zeolite group minerals on the migration of reservoir fluids in terrigenous deposits, complex (X-ray and gas-geochemical) studies of core material in the Yamal oil and gas region field were conducted. 54 core samples from the Pyakyakhinsky and Yuzhno-Messoyakhsky deposits were studied including 43 zeolitized and 11 non-zeolitized samples.

Geological and geophysical analysis of morphological structures of the central type in the Eastern European platform territory and its connection with hydrocarbon fields

Authors: Kharitonov A. L.

Correlative interrelation of hydrocarbon field arrangement and morphological structures of the central type is revealed. Possible natural mechanisms of morphological structures formation of the central type are considered. By results of geological and geophysical interpretation of magnetic prospecting, gravity prospecting, heat floor data the deep structure of these morphological structures is shown.

Structural features of the lower permian salt-bearing series and the character of salt-tectogenesis manifestations in the northern and northwestern margins of the Сaspian depression. Paper 1

Authors: Pisarenko Y. A., Goncharenko O. P., Pisarenko V. Y.

The detailed evaluation of the accumulated geological-geophysical data, particularly on the inner structure of the saltbearing series in the margins of the Caspian Depression, the mechanism of salt-tectogenesis manifestation, its reflection in the structure of the salt table and association with the structural inhomogeneities of the subsalt bed is presented. The authors attempt to acquire additional indirect criteria for predicting the structure of the subsalt bed by means of analyzing the structure of the salt-bearing series and the character of salt-tectogenesis manifestation.

Volcanogenic material in upper jurassic-lower cretaceous deposits of the Eastern Russian plate and its sources

Authors: Nikashin K. I., Zorina S. O.

Widespread “camouflaged” pyroclastics including smectite, illite-smectite and heulandite are detected in the upper jurassic– lower cretaceous deposits of the Ulyanovsk-Saratov basin. Moreover, volcanic glasses are found in several stratigraphic units. The quantity of pyroclastic material in the study section (17–72%) is probably related to volcanic input in the basin. Concentrations of the trace and rare earth elements point to a predominantly acid source of ash material, except the Promzino and Ulyanovsk black shale formations linked to the mixed andesite-basaltic and felsic sources.

Cribricyaths of the Lower Cambrian Oldynda Suite (Western Transbaikalia)

Authors: Skripnikov M. S., Vetluzhskikh L. I.

A large number of cribricyaths previously considered as archaeocyathan larvae was found in the carbonate deposits of Oldynda suite. Described by A. G. Vologdin in 1932 cribricyaths are characteristic of the lower Cambrian deposits of Ural-Mongolian belt and are rarely found outside of it. They are known from the Tommotian of Altai-Sayan folded area and their further development took place on the periphery of the Siberian platform.

The Reversal Polarity Zone in Turonian-Coniacian of the Northern End of DonoMedvediza Dislocations

Authors: Gujikova A. A., Pervushov E. M., Ryabov I. P., Fomin V. A.

The Gubkino Horizon (Turonian-Coniacian) in the Bolshoy Kamenny ovrag section (Zhirnovsk town, Volgograd Region) has not been purposefully studied so far. As a result of biostratigraphic and magnetostratigraphic researches the carbonate rocks of the Gubkino Horizon were first divided into zones based on benthic foraminifera complexes and characterized by geomagnetic polarity and rock-magnetism data. The most part of the Bolshoy Kamenny ovrag section is covered by the reverse polarity zone.

The Santonian Stage in Volsk-Khvalynsk Structural Zone. Paper 2. Biostratigraphy and the Modern Structural Position

Authors: Pervushov E. M., Seltzer V. B., Kalyakin E. A., Ryabov I. P.

The fossil assemblage taxonomical composition analysis of upper Coniacianlower Santonian, upper Santonian and lower Campanian deposits is demonstrated. The upper Coniacian and lower Santonian deposits planoconformity has been recorded, the thin upper Santonian deposits presence has been proved and the lower Campanian subface position has been defined. Fractional biostratigraphy subdivision of the Coniacian – lower Campanian interval was carried out. The distinguished strata were traced within Volsk-Khvalynsky district.

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