Геология

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.

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.

This article describes the skeletal fragments of new species of ichthyosaurus Nannopterygius mikhailovi sp. nov. and Nannopterygius yakimenkae sp. nov. from the Upper Volga sublayer of the Upper Jurassic of the West Kazakhstan region of the Republic of Kazakhstan (Shchuchkino section). The species are assigned to the genus Nannopterygius.

The deep structure and formation of the North Caspian (Precaspian) depression have not been fully understood due to the scarcity of depth studies at 18–22 km. The existing concepts and hypotheses are clearly insufficient to interpret the unexplained facts. New approaches and research efforts are necessary to solve the old problems. The current state of the depression deep structure problems is reviewed, and the existing explanation flaws are demonstrated. The depression consolidated crust has oceanic and riftogenic origin as it has been suggested by the author before.

The Shalkar earthquake focal zone is characterized by the strongest earthquakes of all that occurred in the southeast of the East – European Platform. A physical and geological model has been developed, on the basis of which the parameters of the Shalkar earthquake focal zone have been determined, which can be used to assess the intensity of shaking from possible earthquakes. The relationship between earthquakes in the southeast of the East European platform and deformations in the mantle is shown.

The paper is meant to prove that structural reconstruction of riftogenic basins is accompanied by the intensification of tectonichydrothermal activity. It controls the mobility of gaseous-liquid hydrocarbons during their primary and lateral migration in the process of deposit formation. The intensity index of tectonic-hydrothermal activation is equal to the ratio of maximum paleotemperatures of gaseous-liquid inclusions to the paleotemperatures calculated from vitrinite reflectance values.

The paper presents the results of petro- and paleomagnetic studies of two sections of Turonian – Santonian on the Samara Right Bank – near Novodevichye, Podval’e villages and detailed geological description of the Novodevichye section. The magnetostratigraphic subdivision and detailed correlation of the sections were carried out. Unknown unconformity in the Podval’e section was recognized.

In the established practice of geological exploration for oil and gas conclusions about the facies belonging of the rocks of oil and gas basins and individual exploration areas were made mainly on the basis of the study of core material. Recently for this purpose the results of seismic exploration and well logging have been used. Geophysical methods despite their obvious progress are indirect and intermittent core sampling and incomplete coring make facies analysis difficult.

Geological and geophysical modeling is a modern and classic method of processing and interpretation, which is relevant in the segment of geological exploration of any geophysical method. The article presents the material of two-dimensional modeling based on the results of gravity and seismic exploration in the licensed areas of the Saratov region.

The article presents the methodology of the representative elementary volume definition for 1 m long whole core segments. Scientific articles focused on factors controlling elastic properties are analysed. Terms of additivity and nonadditivity for physical properties of rocks are discussed. The algorithm of core sampling including drilling out of three perpendicular core samples for estimation of elastic anisotropy was used.