Search

A structural model is developed for the south-central Taiwan fold-and-thrust belt that shows consistency across an array of data types and marks an important step forward in the consideration of geological hazards and risks. Although there is general agreement about the regional scale geology of Taiwan, there are considerable differences in the structural interpretations of its western fold-and-thrust belt. In this paper, we bring together results of our previous studies and add new data and data analyses to develop a consistent 3D structural model for the south-central Taiwan fold-and-thrust belt that can explain key aspects of the seismicity, GPS, and topography data. We interpret the fold-and-thrust belt to be a west-verging, imbricate thrust system developed above a single basal thrust that is breached by ENE-striking faults that are inherited from the continental margin. These breaching faults are associated with ENE-striking transverse zones in the fold-and-thrust belt that are marked by changes in stratigraphy, structural style, strike and dip of the basal thrust, and uplift of the stratigraphic contacts. Along the eastern flank of the fold-and-thrust belt, metamorphic basement rocks are involved in the thrusting. Shortening estimates range from 15 km to >25 km. Much of the seismicity is taking place beneath the basal thrust, in the basement, along the flanks of basement highs and lows where strike-slip and transpressive fault types are common. There are systematic changes in GPS displacement vectors and strain rates across the transverse zones. Topography is higher in areas where basement is involved in the thrusting. The proposed structural model has depth and along-strike consistency, and can explain aspects of the distribution of seismicity, faults types, GPS displacement vectors and strain rates, and topography of the study area, and can therefore be considered a viable model.

The method of deep seismic sounding (DSS), the observation systems in which are characterized by an irregular arrangement of both sources and receivers along the profile, a significant step between receivers, as well as maximum source-receiver distances exceeding several hundred kilometers, makes it possible to obtain an image of the crystalline basement using seismic migration fields of reflected/refracted waves. The main part of the existing migration methods, the use of which makes it possible to form an image of the deep structure of the study area in the dynamic characteristics of the recorded wave field, is focused on processing seismic data obtained by the method of reflected waves with multiple overlap observation systems (MOV—CDP). And, as a rule, these migration methods are designed for a smooth change in speed with depth. At the same time, at the boundary of the crystalline basement, the speed changes very sharply, which must be taken into account when processing data using migration. The proposed method for constructing an image of the crystalline basement is based on the use of finite-difference migration of the field of reflected/refracted waves, which was developed at the Institute of Geophysics named after S. I. Subbotin National Academy of Sciences of Ukraine. This migration method is designed to isolate supercritically reflected and refracted waves recorded from the basement in the far zone of the source and takes into account the full trajectory of waves passing through a two-layer medium, at the boundary of which there is a significant jump in velocity. Thus, the migration of the field of reflected/refracted waves makes it possible to obtain a correct image of the structure of the refractive layer of the crystalline basement. The article describes in detail the algorithm of the technique for constructing an image of the crystalline basement using finite-difference migration of the field of reflected/refracted waves and its difference from similar

In this work we report the ongoing characterization of the Sos Enattos former mine (Sardinia, Italy), one of the two candidate sites for the Einstein Telescope (ET), the European third-generation underground interferometric detector of Gravitational Waves. The Sos Enattos site lies on a crystalline basement, made of rocks with good geomechanical properties, characterized by negligible groundwater. In addition, the site has a very low seismic background noise due to the absence of active tectonics involving Sardinia. Finally, the area has a low population density, resulting in a reduced anthropic noise even at the ground level. This location was already studied in 2012-2014 as a promising site for an underground detector. More recently, in March 2019, we deployed a new network of surface and underground seismometers at the site, that is currently monitoring the local seismic noise. Most of the energy carried by the seismic waves is due to the microseisms below 1 Hz, showing a significant correlation with the waves of the west Mediterranean sea. Above 1 Hz the seismic noise in the underground levels of the mine approaches the Peterson's low noise model. Exploiting mine blasting works into the former mine, we were also able to perform active seismic measurements to evaluate the seismic waves propagation across the area. In conclusion we also give a first assessment about the acoustic and magnetic noise in this underground site.

Latvia is a State near Baltic Sea formerly included in Soviet Union that hardly classified all types of cartographical and geological information making it not available for scientific evaluation. Geological mapping data, deep boreholes with cores available from various depth up to crystalline basement (>1km), intersections and seismic data from 60-ties indicate the existence of an enigmatic structure similar to structural forms called astroblemes; it is located south of the town of Dobele in Latvia N56°35’ E23°15’. The structure at the beginning was suspected as kimberlitic pipe; however, gravimetric and magnetometer data did not approve these suspicions. The impact crater formed in between Late Triassic and Early Quaternary time; the age is not known precisely and one of versions of evolution of structure is possible explosion of a meteorite 2-5 km high above the land. Hydrogeological and geochemical data is contradictory to structural evidence therefore, a new survey including modern geophysical methods is highly recommended. The aim of this paper is reviewing of archived classified data from expedition reports of geological mapping events never published before and emphasize the need to recover hidden data about the formation of Dobele impact structure according to available research data and recommend future research approaches to shed light on unclear questions. The field geological mapping expedition was in charge during whole study of Dobele structure. The most devoted person to find the answers of development of the Dobele structure was Mr. Atis Murnieks, who left this world in summer 2017. © SGEM2018.

The materials of structural-thermal-atmo-geochemical research (STAGR) carried out within Yuliyivsko-Skvortsivsky polygon are analyzed. The relationship between geological structure, structural-tectonic position of Yuliyivsko- Skvortsivskiy polygon, patterns of distribution of hydrocarbons deposits within it and the nature of the fields produced by them are characterized. The most promising and relatively promising areas in terms of oil and gas bearing capacity are selected.

The paper deals with consideration (in light of recent geologic-geophysical data generalization and from the standpoint of specific features of continental riftogenesis) petroliferous regularities of the basement of the Northern flank of Dnieper-Donets aulacogen. Certain tectonic-geodynamic criteria of hydrocarbon pools presence within deconsolidated Archean-Lover-Proterozoic crystalline rocks are suggested.

Ökande oljepriser och en stigande efterfrågan gör idag undersökningar av alternativa petroleumreservoarer extra intressanta. Istället för att borra i den sedimentära berggrunden ges nu möjligheten att granska kristallina berggrundsreservoarer. Den här typen av borrning i kristallin berggrund äger rum på flera platser i världen, exempelvis i Vietnam och Yemen. Det norska företaget Lundin Norway AS har funnit petroleum i vittrade graniter i kärnborrsprover från Utsira höjden, sydvästra Norge. Att utföra borrningar och undersökningar offshore kan vara både dyrt och komplicerat. Granskningar och analoga undersökningar onshore kan därför vara att föredra då de tillför viktig information och bidrar med ökad kunskap för de aktuella områdena. Berggrunden på Bømlo är nära besläktad med berggrunden på Utsira Höjden. Detta gör den lättåtkomliga ön ett högkvalitativt undersökningsområde. Det vittrade materialet med petroleumfynd från Utsira Höjden gör att även Ivön, sydöstra Sverige, med sin likartade historia i ålder och petrologi blir en viktig nyckellokal för att förstå petroleumförekomster i vittrad berggrund. Naturliga skärningar på Ivön visar skarpa konturer mellan vittrat berg och färskt, ovittrat berg. Denna uppsats tar upp samband och möjligheter till hur petroleum kan påträffas i kristallin berggrund., Rising oil prices and an increasing global use of fossil fuels make the survey of alternative petroleum reservoirs of great importance. Instead of drilling in regular sedimentary successions, the possibility of investigating reservoirs in crystalline basement is in many places of economic interest. Reservoirs in crystalline basement rock are producing oil in several countries e.g. Vietnam and Yemen, and oil exploration including drillings are made continuously to look for reservoirs in basement rocks in other places. The Norwegian company Lundin Norway AS has found traces of petroleum in weathered granites in drill cores from the Utsira High, southwestern Norway. Drilling and survey offshore can be expensive and difficult while analog research onshore could result in significant information and increased knowledge. Bømlo basement is related in age and petrology with the basement of Utsira High. This makes the, easy accessed, onshore island to a high quality survey area. The weathered material with petroleum occurrences from Utsira High makes Ivön, southeastern Sweden, a key locality since the latter area yields several good exposures where the relationships between deep weathered basement and unweathered basement can be studied. This thesis details the development of petroleum occurrences in crystalline basement.

Inheritance by Early Riphean near-surface structures and paleotopography of tectonics of deep horizons of the lithosphere, reflected at the level of Mohorovicic discontinuity is considered. This tectonics in the conditions of destruction of crystalline basement determined the origination and further making pre-plate sedimentary cover which basal horizon is filled with many minerals.

The long continental period in the East of the Russian plate (the upper Proterozoic ? the middle Devonian) caused the formation of a weathering crust on the crystalline basement rocks. In pre-Devonian time, due to the washing-out and the subsequent processes of redeposition of substance, two types of weathering crust were formed: displaced and non-displaced. The widespread weathering crust of the crystalline basement of the East of the Russian plate is a unique object for studying the mineral formation processes of ancient weathering. Complex mineralogical and geochemical studies of the weathering crust are of practical value for the creation of a full picture of the development of the deep horizons of the earth crust and a forecast of mineral deposits.

© 2019, Neftyanoe Khozyaistvo. All rights reserved. The article is devoted to the fundamental problem of petroleum geology-the hypothesis about the replenishment of reserves of oil deposits in the process of their development. The increase in recoverable reserves of oil fields due to the process of modern injection of deep oil in the sedimentary cover is an important and actual task. Also, the localization of such zones of injections is a very serious scientific and practical task. The solution of this task requires carrying out complex field-ge-ological and geochemical studies in the monitoring mode for a long time. This is necessary to obtain quantitative parameters of the flow and injection of light hydrocarbons in the oil fields. These works will allow to select the most promising areas of the reservoir to search for channels for the deep hydrocarbons degassing and recommend conducting seismic studies on new innovative technologies with the aim of mapping the channels and subsequent monitoring of the degassing processes. The newly obtained results, together with the already available information, will allow a new approach to the development of an alternative geological and hydrodynamic model, which allows determining the rate of regeneration of deposits in the development process and the volume of “replenishment” of hydrocarbons from the depths, as well as predicting the role of processes of re-formation of deposits in total production of oil. The process of injection of the light hydrocarbons into the oil reservoir needs to be studied and taken into account for planning the development of oil fields, for estimating residual oil reserves, for determining the terms of “life” of fields, for formation geological and hydrodynamic models of fields. The process of deep flow of fluids during mass and heat transfer is important for the formation and re-formation of hydrocarbon deposits in various geological and physical conditions. It is promising to create geological m

© SGEM2019. There are the structural-material complexes of the rocks in the crystalline basement of the Volga-Ural oil and gas province, which characterized by different composition and structural position. The biggest structure, which occupies a central position in the region, is the Tatar arch. The Tatar arch is a large megablock of the lithosphere (granite-gneiss core) bounded by mobile zones (graben-shaped deflections). They are associated with pre-metamorphic basic magmatism. The areas of the crust bounding and separating the granite-gneiss domes are zones of a repeated diaphtoresis process. In the Archean-Proterozoic, the rock complexes underwent a regional metamorphism of the granulite facies and at the regressive stage the amphibolite facies. Rocks of mobile belts were drilled by deep parametric wells. They are represented mainly by biotite-, amphibole-, pyroxene-containing gneisses, plagiogneisses, and rarely crystal shales. The layer of gneisses and plagiogneisses is heterogeneous in petrographic composition. It was probably formed by various rocks of predominantly basic composition. In the Archean period, they underwent a metamorphism of granulite facies. In the early Proterozoic, rocks underwent ultrametagenic process with partial granitization. Their modern morphology was formed as a result of subsequent diaphtoresis in the conditions of the amphibolite facies. The findings of relict pyroxene grains in amphibole and biotite crystals and relict phaneritic texture indicate that the original rocks were primary magmatogenic and sedimentary-volcanogenic rock complexes. These rock complexes formed from ancient ultrabasic-basic substrate. They are characterized by an appropriate composition of trace elements. Elevated concentrations of such elements as Cr, Ni, Zr, indicate the participation of ultrabasic rocks in the formation of the complex. Almost throughout the all section, the rocks are broken by a rare network of cracks, filled with red oxide material and

© 2019, Georesursy LLC. All rights reserved. The history of studying the crystalline basement in the Republic of Tatarstan, the state of implementation of the super-deep drilling program is given. The scientific substantiation of the replenishment of exploited oil and oil-gas fields is provided by feeding them with deep hydrocarbons through oil supply channels connecting the deep source of hydrocarbons with sedimentary cover deposits. The crystalline basement is of interest for the search for hydrocarbon deposits, but its role as a transit for replenishing deposits of hydrocarbon sedimentary cover in the process of constant degassing of the Earth is more attractive and justified. To use these processes, a fundamentally new approach to the construction of geological and hydrodynamic models of oil fields is proposed, taking into account the fundamental principles of geological science on the formation and reformation of oil deposits and the deep processes of Earth degassing. Prospects are substantiated for the development of “old” fields that are in long-term development, for the calculation of oil recovery factor taking into account oil entering the reservoir from the depths of the Earth, the need for adjusting methods for calculating and accounting reserves, changing levels of material balance, and scientific and practical suggestions for accounting when calculating reserves and designing the development of fundamental principles of field geology. Further prospects for the introduction of hydrodynamic development methods and their significant expansion due to the opening of the processes of replenishment of sedimentary basin deposits with deep hydrocarbons and the reformation of deposits at a late stage of development are shown.

© SGEM2019. The crystalline basement of the East European Platform is composed of metamorphic rocks of the Archean-Proterozoic age. They are interesting as products of fluid-magmatic differentiation of the primary crust, which led to the formation of the early continental crust. The Volga-Ural segment of the crystalline basement is located in the east of the platform. It is covered by a sedimentary cover up to 1.5-2.0 km and was opened by the deep oil drilling. Based on the study of the obtained materials it was established that the crystalline basement within the Volga-Ural segment is composed of metamorphic complexes of granulite and amphibolite facies. The rocks have different genesis and age. They were formed in environments with different tectonic regimes and metamorphosed. Granite-gneiss domes located at the central part of the arch uplifts. Their formation is associated with the processes of metamorphic and metasomatic processing of the primary crust of the basic-ultrabasic composition. Within the crystalline basement of the Tatar arch granite-gneiss complexes are composed of highly metamorphosed, partially migmatised mafic and high-alumina rocks. Mafic rocks are metamorphic altered associations of igneous rocks of predominantly basic composition (Otradnenskaya series). The high-alumina rocks are composed of metamorphosed primary sedimentary rocks (Bolshecheremshanskaya series). The original nature of these rock complexes causes debate. Sensitive indicators of geological processes are the minerals of the garnet group. Their formation in the rocks of the crystalline basement is associated with the anatectic melting of the original rocks. All of the investigated garnets belong to the almandine series, but they are characterized by variability of the chemical composition. The different chemical composition of almandines notes to the different chemical composition of the substrate from which the almandines crystallized. Thus, the composition of almandine reflects

© SGEM2018. The crystalline basement of the Tatar arch located in the eastern part of the East European Platform (Russia) is composed of the metamorphic rocks of different composition and genesis. The Tatar arch consists of two blocks of the basement. The North Tatar and the South Tatar blocks are separated by a faults system. The South Tatar arch is a granite-gneiss core of the basement. It is composed of Archaean-Proterozoic metamorphic complexes of rocks (granite-gneisses, gneisses, migmatites and granulite-gneisses). The moving zones that separate them are composed of metabasite complexes. Metamorphic rocks of the crystalline basement of the Tatar arch are formed under the conditions of the granulite facies of a regional metamorphism. The associations of rocks are combined into structural and material complexes, the largest of which are the Otradnenskaya and the Bolshecheremshanskaya series. Otradnenskaya series is composed of rocks of mafic composition (metamorphosed volcanogenic, volcanic-sedimentary and intrusive formations), while the Bolshecheremshanskaya series is composed of the rocks of high-alumina composition. Many researchers identify them with metapelites. Granulite rock complexes are migmatized and granitized in various degrees. The rocks of the crystalline basement of the Volga-Ural oil and gas province have been drilled by great number of boreholes. The most profound is the 20009 Novo-Elkhovskaya well as deep as 5.5 km. One of the most important tasks is the stratigraphic dismemberment of the metamorphic complexes of the basement. Because of the absence of paleontological remains for their dismemberment, the material composition of the rock complexes can be used (mineralogical and geochemical features). In this connection, the radiation samples were estimated in terms of the content of natural radionuclides by emitting elements-232 Th,40 K,226Ra with the determination of their activity (A, in Bq/kg). There are 5 packs of rocks in the section of We

© SGEM2016.Conducting of quantitative mineralogical analysis of metamorphic rocks penetrated by deep wells in the territory of the South-Tatar arch (East of the Russian Plate) provided an opportunity to examine and identify the leading formational types of rocks or metamorphic formations. According to the results of long-term mineralogical and petrographic research, followed by petrochemical analysis, the rocks have been grouped into two major formations. The first one – mafic-silicate formation is characterized by a predominance of mafic and mafic-silicic rock complexes. Ortho and clinopyroxene, amphibole and biotite are leading femic minerals. The second formation – high-alumina formation is characterized by a wide development of cordierite, sillimanite, garnet, biotite. The content of pyroxene, amphibole among the rocks of this formation is reduced dramatically. Leucocratic mineral component of these two formations is the same. However, the relation between minerals within the formation is different. Formation of buried weathering crust is located on the border of the sedimentary cover and the surface of crystalline basement. It was found that the material composition of the weathering crust is associated with mineralogical and petrographic features of leading metamorphic complexes. The mineral composition of weathered rocks, peculiarities of the development of finely dispersed and clay minerals in various areas of the crystalline basement are also variable and related to the original composition of the substrate in the studied territory.

The study area is the South Tatarstan Arch located in the Volgo-Ural Region, which is an enigmatic crustal segment occupying one third of the East European Platform. Monitoring studies have shown that fluid discharge processes are still active and time-dependent. This paper presents an integrated review of the geological, geophysical, hydrochemical and geochemical studies of the crystalline basement of Tatarstan. These studies are based on the stratigraphic and compositional schemes within the crystalline basement, the drilling of deep wells, the geodynamic activity of the fractured zones of the crystalline basement and the presence of fluids therein. Furthermore, the changes in the chemical composition of the basement waters are taken into account. © Springer-Verlag 2008.

© SGEM2014. All Rights Reserved. Due to the prospects of hydrocarbons content of the deep horizons of the east of the Russian plate the study of the mineral-geochemical features of the rocks of the basement is actual. The great information is given by carrying out deep drilling and analysis of the core material of the bore holes, which revealed the buried weathering crusts on the border of the sedimentary cover and the basement.

Analysis of the distribution of oil pools in sedimentary cover has shown that known platform hydrocarbon fields are closely associated with faults in the crystalline basement and the sedimentary cover itself. Oil pools in the lower productive beds of the sedimentary cover are linked to faulted zones in the crystalline basement. A genetic relationship between oil fields and tectonic dislocations indicates a dominant role for vertical migration in the accumulation of commercial hydrocarbons in the Paleozoic. The conducted geochemical, palynological, geophysical and geological studies have shown that oil and gas pools in the upper sedimentary cover have been formed due to the vertical migration of hydrocarbons, which is also confirmed by the vertical alignment of the oil pools. © 2006 Elsevier B.V. All rights reserved.

High-precision temperature logging in deep and superdeep wells has permitted the study of the thermal regime in the granite-gneiss layer of the Earth's crust. The long-term logging works have allowed the classification of temperature anomalies recorded in the crystalline basement. Most anomalies have been supposed to be caused by loosely aggregated, permeable zones. The classification reflects main types of processes at a great depth - such as injection, inflow and upward migration of gas-cut fluid. The results of great practical importance are obtained using our classification: some intervals - where temperature anomalies interpreted as inflow reservoirs were revealed - have produced fluid, and others interpreted as injection reservoirs absorbed borehole fluid during tests. © 2006 Elsevier B.V. All rights reserved.

© SGEM2017. All Rights Reserved. The Volga-Ural oil and gas province is one of the oldest oil-producing regions in Russia. The central position in its borders is occupied by Tatarstan, in the territory of which is explored the largest oil deposits of the region. Oil deposits belong to the Devonian sediments, and in a lesser degree to the Carboniferous and Permian deposits. Despite the high degree of research of the region, the origin of oil deposits still one of the most controversial issues. Most researchers consider that the source of oil is the organic-rich strata of the Devonian - domanikites, which mostly fill depressed areas on the surface of the crystalline basement. Their largest capacities are confined to the zone of the Melekess depression, the northern part of which is the most elevated and located on the territory of Tatarstan. However, the thickness of sedimentary rocks here mostly does not exceed 2 km. Based on the geothermal gradient, this depth is not enough to start the processes of oil formation. According to the data from field researches, conducted on oil wells, the maximum temperature difference at the absolute level of -1000 meters in the Volga region reaches 30°C. Temperatures range from 14.25°C to 48.20°C. The structure of the thermal field is closely related to the tectonic structure of the territory and is characterized by relatively low temperatures in the area of the North Tatar arch and their increase in the areas located within the South Tatar arch and the adjacent sections of the Melekess depression. Studies of the catagenetic maturity of organic matter in domanikites and the upper carbonaceous coal, carried out on the reflectivity of vitrinite, have showed that their organic matter is characterized by a greater degree of conversion than can be achieved at modern temperatures. Thus, it can be assumed that the formation of oil deposits in the region occurred as a result of the effect of heat fluxes of deep origin. In favor of this point

© SGEM2017. All Rights Reserved. The Volga-Ural oil and gas province is one of the oldest oil-producing regions in Russia. The central position in its borders is occupied by Tatarstan, in the territory of which is explored the largest oil deposits of the region. Oil deposits belong to the Devonian sediments, and in a lesser degree to the Carboniferous and Permian deposits. Despite the high degree of research of the region, the origin of oil deposits still one of the most controversial issues. Most researchers consider that the source of oil is the organic-rich strata of the Devonian - domanikites, which mostly fill depressed areas on the surface of the crystalline basement. Their largest capacities are confined to the zone of the Melekess depression, the northern part of which is the most elevated and located on the territory of Tatarstan. However, the thickness of sedimentary rocks here mostly does not exceed 2 km. Based on the geothermal gradient, this depth is not enough to start the processes of oil formation. According to the data from field researches, conducted on oil wells, the maximum temperature difference at the absolute level of -1000 meters in the Volga region reaches 30°C. Temperatures range from 14.25°C to 48.20°C. The structure of the thermal field is closely related to the tectonic structure of the territory and is characterized by relatively low temperatures in the area of the North Tatar arch and their increase in the areas located within the South Tatar arch and the adjacent sections of the Melekess depression. Studies of the catagenetic maturity of organic matter in domanikites and the upper carbonaceous coal, carried out on the reflectivity of vitrinite, have showed that their organic matter is characterized by a greater degree of conversion than can be achieved at modern temperatures. Thus, it can be assumed that the formation of oil deposits in the region occurred as a result of the effect of heat fluxes of deep origin. In favor of this point

© SGEM2016.Conducting of quantitative mineralogical analysis of metamorphic rocks penetrated by deep wells in the territory of the South-Tatar arch (East of the Russian Plate) provided an opportunity to examine and identify the leading formational types of rocks or metamorphic formations. According to the results of long-term mineralogical and petrographic research, followed by petrochemical analysis, the rocks have been grouped into two major formations. The first one – mafic-silicate formation is characterized by a predominance of mafic and mafic-silicic rock complexes. Ortho and clinopyroxene, amphibole and biotite are leading femic minerals. The second formation – high-alumina formation is characterized by a wide development of cordierite, sillimanite, garnet, biotite. The content of pyroxene, amphibole among the rocks of this formation is reduced dramatically. Leucocratic mineral component of these two formations is the same. However, the relation between minerals within the formation is different. Formation of buried weathering crust is located on the border of the sedimentary cover and the surface of crystalline basement. It was found that the material composition of the weathering crust is associated with mineralogical and petrographic features of leading metamorphic complexes. The mineral composition of weathered rocks, peculiarities of the development of finely dispersed and clay minerals in various areas of the crystalline basement are also variable and related to the original composition of the substrate in the studied territory.

The study area is the South Tatarstan Arch located in the Volgo-Ural Region, which is an enigmatic crustal segment occupying one third of the East European Platform. Monitoring studies have shown that fluid discharge processes are still active and time-dependent. This paper presents an integrated review of the geological, geophysical, hydrochemical and geochemical studies of the crystalline basement of Tatarstan. These studies are based on the stratigraphic and compositional schemes within the crystalline basement, the drilling of deep wells, the geodynamic activity of the fractured zones of the crystalline basement and the presence of fluids therein. Furthermore, the changes in the chemical composition of the basement waters are taken into account. © Springer-Verlag 2008.

© SGEM2014. All Rights Reserved. Due to the prospects of hydrocarbons content of the deep horizons of the east of the Russian plate the study of the mineral-geochemical features of the rocks of the basement is actual. The great information is given by carrying out deep drilling and analysis of the core material of the bore holes, which revealed the buried weathering crusts on the border of the sedimentary cover and the basement.

Analysis of the distribution of oil pools in sedimentary cover has shown that known platform hydrocarbon fields are closely associated with faults in the crystalline basement and the sedimentary cover itself. Oil pools in the lower productive beds of the sedimentary cover are linked to faulted zones in the crystalline basement. A genetic relationship between oil fields and tectonic dislocations indicates a dominant role for vertical migration in the accumulation of commercial hydrocarbons in the Paleozoic. The conducted geochemical, palynological, geophysical and geological studies have shown that oil and gas pools in the upper sedimentary cover have been formed due to the vertical migration of hydrocarbons, which is also confirmed by the vertical alignment of the oil pools. © 2006 Elsevier B.V. All rights reserved.

High-precision temperature logging in deep and superdeep wells has permitted the study of the thermal regime in the granite-gneiss layer of the Earth's crust. The long-term logging works have allowed the classification of temperature anomalies recorded in the crystalline basement. Most anomalies have been supposed to be caused by loosely aggregated, permeable zones. The classification reflects main types of processes at a great depth - such as injection, inflow and upward migration of gas-cut fluid. The results of great practical importance are obtained using our classification: some intervals - where temperature anomalies interpreted as inflow reservoirs were revealed - have produced fluid, and others interpreted as injection reservoirs absorbed borehole fluid during tests. © 2006 Elsevier B.V. All rights reserved.