GENETIC MODEL OF MUD VOLCANISM OF THE KERCH PENINSULA (SCIENTIFIC AND APPLIED ASPECTS)

The work is devoted to the results of many years of research and observations of mud volcanoes on the Kerch Peninsula. It aims to reveal the most important factors and aspects related to their origin, activity and impact on the geological history of the region. About 50 fossil and modern mud volcanoes have been defined on the Kerch Peninsula and the adjacent part of the water area. Their activity is consistent with the phases of activation of the alpine tectogenesis of the Crimean-Caucasian segment and is intermittent and impulsive. In the geological history of the peninsula, four main bursts of mud volcanic activity are clearly recorded: in the Upper Maikop, Chokrak-Karagan, Sarmatian and Cimmerian. Its greatest activity is manifested in the late Miocene and early Pliocene. Favorable factors for the development of mud volcanoes within the peninsula are the presence of a thick layer of plastic clays enriched in water and gas fluids, the widespread development of brachyanticlinal folds in the Neogene structural surface and a network of deep faults and fractures. The activity of mud volcanoes is associated with the formation of specific compensation structures – depressed synclines, which have become widespread on the Kerch Peninsula. The latter, depending on the paleogeographic conditions (sea, land) and the structural position of volcanoes in the anticlines, have acquired different specifics of structure and filling. Some depressed synclines are associated with iron ore deposits, which differ from typical iron ores of the mulde type by significant capacity, structural and textural features and material composition. Components of hydrothermal and exogenous origin have been defined in the products of mud volcanism: mud gases, mud waters, mud breccias, which indicates the genetic connection of this phenomenon with deep and near-surface processes. In addition, liquid, solid and gaseous hydrocarbons are often detected in volcanic eruptions. The latter are a criterion for searching for oil and gas at depth. Mud volcanoes of the Kerch Peninsula are a unique testing ground for monitoring the processes of modern mineral formation, the dynamics of deep processes and seismic activity in the region.

ZONES OF RECENT ACTIVATION AND SCHEME OF THE EARTH CRUST PERMEABILITY OF UKRAINE

An attempt is considered to supplement the criteria for identifying zones of recent activation in the territory of Ukraine with another one — data on the results of studies of helium concentration in ground-water. The previous analysis of information showed that as regional criteria, information can be applied on anomalies in heat flow, increased electrical conductivity of Earth’s crustal and the upper mantle rocks, distribution of mantle gravitational anomalies, and surface uplifts over the past millions of years. They were chosen among others precisely because of the dissemination of relevant information throughout the country. This requirement is also met by the permeability Scheme of the earth’s crust of Ukraine, which is a fragment of the permeability Scheme of the earth’s crust of the European part of the USSR based on the results of helium studies. The principal applicability of such information for solving the problem is shown. Areas of maximum helium concentrations in near-surface waters are indicated, primarily those associated with disjunctive dislocation. Theу are concentrated in the south-west of Ukraine and in Moldova. The disadvantages of the Scheme are noted, due to poor study and significant variations in background gas concentrations, directly caused not by recent activation, but by the peculiarities of helium generation by rocks of the upper part of the earth’s crust. There are inconsistencies between the previously obtained ideas about the activated zones and the data of the Scheme. They are especially large in the Carpathian, Crimean and Donetsk regions, and are noticeable in others. Therefore, it seems necessary, first, to continue research, thicken the network of observations and develop a methodology for analyzing their results.

GAS CHIMNEYS IN THE NW BLACK SEA NEAR THE KALANCHAK PALEOBRIVER

The publication is based on a large body of data on gas outcrops in the northwest of the Black Sea, and in particular, the paleo-Kalanchak area. The material was obtained during the voyages carried out on the R/V of the Department of Marine Geology and Sedimentary Ore Formation of the National Academy of Sciences of Ukraine, as well as data from literary sources. More than 3000 methane sips were identified in the study area. The vast majority of gas emissions in the area of paleo-river Kalanchak, as well as in other areas of the northwestern sector of the Black Sea, is confined to the upper part of the continental slope and the adjacent area of the shelf. Practically it is a band 45 km wide on both sides of the shelf edge. Seismic and acoustic profiles were studied in this article. Their analysis indicates that gas chimneys are not distributed randomly but concentrated in specific locations. A certain relationship between the spatial distribution of methane outcrops on the seafloor and geomorphological structures, as well as tectonic structure, primarily faults is traced. Gas chimneys are associated with various forms of seafloor topography, but their greatest number is located at the mouths of paleo-river canyons. The article provides more detailed geomorphological information of the paleo-river network of the NW Black Sea. In the estuarine canyon, gas emissions form along the sedimentary ridges, gas chimneys appear at the bottoms of canyons, their peripheries, or near the dumps of submarine landslides, where the sedimentary cover is disturbed by mass transport. On the shelf, the greatest concentration of gas chimneys is found in circular and elongated depressions (pockmarks). Based on the study of acoustic profiles, gas chimneys of the Paleo-Kalanchak part of the Black Sea were classified according to a few features: the depth of location, height of gas release, gas flow capacity, form of gas release, mode of operation. The results of the research are also presented in graphical materials (histograms of gas chimneys distribution by depth and height of gas discharge, map of sip location by the Paleo-Kalanchak River area).

GAS SIPS AND SHALLOW ACCUMULATIONS OF GAS ON THE SHELF OF TURKEY IN THE BLACK SEA

It has been suggested that shelf and slope sediments of high deposition rate are methane sources, whereas the deep basin is methane sink. The methane production and migration in sediments may cause massive slope failures so methane is geologically important. Methane production is also economically important as methane seeps may indicate the presence at depth of hydrocarbon reservoirs, and methane hydrate may be an important source of energy. Recent studies in marine geology indicate potential geo-resources in the Turkish coast of Black Sea. The Black Sea sediments are rich in calcite and organic carbon, the latter showing a high degree of preservation due to anoxia in the waters below 100-150 m. Different marine geophysical surveys at different times were carried out in order to understand the sedimentary features of gas-saturated sediments in the Black Sea. Multibeam, side scan sonar, sub-bottom profiler and multi-channel seismic data were collected to make both high-resolution bathymetric and reflectivity maps of the seafloor. In some cruises, deep-tow combined side scan sonar and subbottom profiler was used to obtain acoustic images of both the seafloor surface and subbottom sediments. Several different structures were observed in the Black Sea basin as slumps, pockmarks, faults, gas chimneys, shallow gas accumulations and dome-like structures. Structures, which contain gas hydrates, are present on the seismic sections as strong acoustic reflections.

History and prospects of research of the Black Sea estuaries

Black Sea estuaries are phenomenon of geological nature and are not only an important component of the Black Sea geoecosystem, but also they are important component of local and regional ecological, socioeconomic systems of the coastal territory of Ukraine. Affecting the livelihoods and wellbeing of the population of these systems, estuaries from ancient times have attracted the attention of researchers. Unfortunately, the ecological status of these reservoirs has been worsening over the last decades because of the complex of reasons that require comprehensive study, analysis, development and implementation of a specific system of action, which cannot be realized without knowing at least the major milestones in the history of the research of these unique formations. Based on the published materials, information on the history of studies of estuaries of the northwestern Black Sea coast has been systematized. The history of the research has been reproduced in chronological order for the largest estuaries of the Black Sea, taking into account the current level of their study and identifying the main problems regarding their ecological status. The article gives a brief description of the current conditions and status of the largest Black Sea estuaries and some facts from the history of their research. In order to preserve the natural value of estuaries for their further research and rational use, the authors propose to use the methodology, the basic component of which is the geoecosystem paradigm, and henceforth study each estuary as a complete geoecological system taking into account all its components (subsystems), elements and conditions, which affect the formation and functioning of all components and the system as a whole. Geoecosystem paradigm together with a certain ecological and economic approach will allow to study in detail the geoecological conditions of water area of estuaries and adjacent territories, to evaluate their geoecological systems in terms of the prospects for their provision of certain services to the individual and / or society. Geoecosystem paradigm also allows to draw conclusions on optimizing the use of resources of these estuaries.

VELOCITY MODEL OF THE UPPER MANTLE OF THE FLANKING PLATEAUS OF MID-OCEANIC RIDGES

A new element is included in the study of velocity sections of the upper mantle of regions of continents, oceans, and transition zones with different endogenous regimes (according to the advection-polymorphic hypothesis — APH). This is the flanking plateaus (FP) of the mid-ocean ridges (MOR). It is assumed that these regions underwent the process of oceanization in the Mesozoic along with other parts of the oceans. In the Neogene MORs were formed. Significant parts of the basins were engulfed in modern activation, including magmatism. Between these parts of the oceans, relatively narrow strips (200—300 km wide) have survived, which some authors refer to as flanking plateaus. They are located at the edges of the MOR. FP did not experience young activization. This is indicated by the features of the bottom topography, magnetic, gravitational and thermal fields, and a velocity section of the upper horizons of the mantle. An element of checking the nature of the FP can be the construction of a velocity section of the mantle beneath these regions. According to the APH, it should differ from the neighboring ones by the increased velocity of seismic waves in the upper about 200 km. The experimental data for such work turned out to be extremely small. It was possible to build only one travel-time, using data on the southern part of the Atlantic Ocean. Insignificant information was also attracted on the southern part of the East Pacific Rise and the Mid-Indian Ridge. The travel-time corresponds to the velocity section, which completely coincides with the forecast. The latter was calculated according to the heat and mass transfer scheme in the APH version and the thermal model of the mantle. The velocity section of the FP mantle does not contain indications of a partial melting layer. Consequently, there should be no manifestations of young magmatism in FP. Verification showed that in most of the studied fragments of MOR this is true.

CLASTIC HETEROFACIAL SEDIMENTS IN THE SEDIMENTARY COMPLEXES OF THE SOUTHERN OIL AND GAS REGION OF UKRAINE

In this article the author carried out sedimentary and genetic modeling of facies parameters within heterogeneous geological bodies based on the analysis of geological and geophysical materials in the Southern Ukrainian oil and gas region. Special attention was paid to clastic facies and parameters demonstrating the degree of heterogeneity and a wide range of facial settings of the sedimentation basin. The data from lithological, geochemical, and geophysical field studies of wells was interpreted to predict hydrocarbon traps. This resulted in the facial diagnostic of the groups of geological bodies of clastic rocks coexisting with sediments of both tectonic and ridge morphological structure of the study area. Such diagnostics allowed us to build a prognostic lithologicfacial (sedimentation) section. Based on the modeling of the Vendian top (Vendian is a stratigraphic unit partially corresponding to Ediacaran) and the Jurassic base, a schematic map of the Paleozoic sediments was constructed for the first time, which made it possible to identify zones of the potential distribution of the former reef structures. The article presents the spatial forecast of hydrocarbon reservoir distribution in geological bodies of oil and gas bearing complexes within the PreDobruja Trough. The data allow forecasting a large number of traps, mainly small ones, formed by clusters of cavernous dolomites, limestones, and mixed rocks confined to certain cyclical elements and, in particular, associated with diastems. Most of such traps are caused by metasomatic dolomitization and paleokarst.