Current problems in the North Caspian depression geology and oil and gas prospects

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. This explanation is supported by the Astrakhan deposit D-2 deep well core data. The Astrakhan-Aktobe zone arched uplift genesis, formation and role in the carbonate platforms emergence are discussed. Deep geothermy and fluid dynamics problems, as well as recent geophysical data are considered in view of the North Caspian depression hydrocarbon prospects.

DEEP CRUSTAL STRUCTURE IN NORTHEASTERN EURASIA AND ITS CONTINENTAL MARGINS

The paper reports on the deep geophysical studies performed by the Geological Survey of Russia (VSEGEI) under the international project – Deep Processes and Metallogeny of Northern, Central and Eastern Asia. A model of the deep crustal structure is represented by a set of crustal thickness maps and a 5400-km long geotransect across the major tectonic areas of Northeastern Eurasia. An area of 50000000 km2 is digitally mapped in the uniform projection. The maps show the Moho depths, thicknesses of the main crustal units (i.e. the sedimentary cover and the consolidated crust), anomalous gravity and magnetic fields (in a schematic zoning map of the study area), and types of the crust. The geotransect gives the vertical section of the crust and upper mantle at the passive margin of the Eurasian continent (including submarine uplifts and shelf areas of the Arctic Ocean) and the active eastern continental margin, as well as an area of the Pacific plate.

Atmospheric transport and mixing of biological soil crust microorganisms

<abstract> <p>Biological soil crusts (BSCs) are created where a diverse array of microorganisms colonize the surface and upper few millimeters of the soil and create a consolidated crust. They were originally described from arid ecosystems where vascular vegetation is naturally sparse or absent. They have since been discovered in all terrestrial ecosystems. Where present, they perform a variety of important ecological functions, including the capture and accumulation of water and essential plant nutrients, and their release in forms useful to vascular plants. They also stabilize the soil surface against wind and water erosion. BSC organisms include fungi (free-living, lichenized, and mycorrhizal), archaea, bacteria (cyanobacteria and chemotrophic and diazotrophic bacteria), terrestrial algae (including diatoms), and bryophytes (mosses and worts). BSC organisms reproduce primarily asexually via thallus or main body fragmentation or production of asexual spores that are readily dispersed by water and wind. Asexual and sexual propagules of BSC organisms are commonly lifted into the air with vast quantities of dust from the world's arid areas. BSC organisms and/or their propagules have been detected as high as the stratosphere. Some have also been detected in the mesosphere. Airborne dust, microorganisms, and their propagules contribute to the formation of essential raindrop and snowflake nuclei that, in turn, facilitate precipitation events. While airborne in the atmosphere, they also reflect the sun's rays passing laterally through the troposphere and stratosphere at dawn and dusk, often causing brilliant colors at sunrise and sunset.</p> </abstract>

New CGMW Tectonic Map of the Arctic

&lt;p&gt;In 2019, the compilation of the new Tectonic Map of the Arctic (Tectonic Map of the Arctic, 2019: eds. O. Petrov, M. Pubellier) was completed. The map was compiled under the international project Atlas of Geological Maps of the Circumpolar Arctic, 1:5M with the participation of representatives of all Arctic states under the auspices of the Commission for the Geological Map of the World at UNESCO. The new 1:5M Tectonic map of the Arctic is a GIS project, which provides a transition to three-dimensional geological mapping of the Arctic. The project includes the crustal and sedimentary cover thickness maps, the crustal types map, the tectonic zonality map of the basement, schematic &amp;#160;map of key igneous provinces of the Circum-Arctic region and the geological transect compiled taking into account the latest scientific geological and geophysical data accumulated in recent decades as a result of high-latitude expeditions and scientific programs to substantiate the extended continental shelf in the Arctic. The new Tectonic map of the Arctic proved the continental nature of the Central Arctic Uplifts as a natural geological extension of Eurasia. Close structural relationships of deep-water parts of the Central Arctic and the shallow continental shelf of Northern Eurasia are substantiated by geological and geophysical characteristics of the consolidated crust, the upper mantle and sedimentary cover, as well as the common parameters of the magnetic and gravitational potential fields.&lt;/p&gt;

THE CHARACTERISTICS OF THE GEODYNAMIC ENVIRONMENT AND ELEMENTS OF STRUCTURAL-MATERIAL COMPLEXES OF THE CENTRAL CAUCASUS AT A DEEP INCISION HEALTHSCOPE PROFILE

В статье рассматривается возможность выделения наследственных признаков геодинамической обстановки и элементов структурно-вещественных комплексов, участвующих в геологическом развитии Кавказа, на глубинных геоэлектрических и сейсмологических разрезах для создания геолого-геофизической моделей земной коры вдоль региональных профилей. Современные структурно-тектонические и структурно-вещественные комплексы восточной части Центрального Кавказа интерполируются с основными структурами консолидированной коры и низов коры. Обосновывается научный и практический интерес корреляционной увязки глубинных коровых и мантийных структур с месторождениями твердых полезных ископаемых и углеводородов, роль границы Мохоровичича в локализации месторождений. Субширотная структура реликтового рубца (геосутуры), уверенно выделяемая по минимумам напряженности полного вектора магнитного поля по структурно-вещественным элементам (олистостромы, офиолиты, микститы) представляется убедительным наследственным признаком субдукции. Реликтовый рубец представляется выполненным тектонизированным терригенным материалом, содержащим разного размера глыбы и блоки вулканогенно-осадочных пород и ремобилизованные олистостромы пород офиолитового комплекса, что является формационным признаком геодинамической обстановки, фиксируемой в развитии структуры Кавказа. The article deals with the possibility of identifying hereditary features of the geodynamic situation and elements of structural and material complexes involved in the geological development of the Caucasus, in deep geoelectric and seismological sections to create geological and geophysical models of the earth's crust along the regional profiles. Modern structural-tectonic and structural-material complexes of the Eastern part of the Central Caucasus are interpolated with the main structures of the consolidated crust and the lower crust. The scientific and practical interest of correlation linking of deep crustal and mantle structures with deposits of solid minerals and hydrocarbons, the role of the boundary of Mokhorovichych in the localization of deposits is substantiated. Latitudinal structure of the relic scar (geostructure), confidently allocated to the minimum of the tension of magnetic field full vector on structural-material elements (olistostromes, ophiolites, mixtite) persuasive inherited character of subduction. Relict scar is represented by tectonized terrigenous material containing different size blocks and blocks of volcanogenic-sedimentary rocks and remobilized olistostromes of rocks of the ophiolite complex, which is a formative sign of geodynamic situation, recorded in the development of the structure of the Caucasus.