Relevance. The Middle Jurassic carbonaceous deposits of the Ulug-Khem basin (Republic of Tuva, Russia) are an available for studying stratigraphic analogue of the source rocks of the oil and gas basins of China (Xishanyao formation J2x) and Western Siberia (Tyumen formation J2tm). The study of their generation properties will allow us to predict the distribution zones of coal-bearing source rocks in adjacent poorly studied areas. Aim and methods. Assessment of the hydrocarbon potential of the Ulug-Khem basin coals based on the results of Rock-Eval pyrolysis. Results. According to pyrolysis data the Middle Jurassic coals of the Ulug-Khem basin have significant hydrocarbon potential. Kerogen is represented by a mixture of types II and III, vitrinite and liptinite in different proportions. The liquid and gaseous hydrocarbons generation potential of coals from the Mezhegey and Elegest coal fields has been mostly realized. The amount of hydrocarbons that could have been produced by the coals reaches very high values – 100–170 mg HC/g of rock. Comparison of the Ulug-Khem basin coals and the Middle Jurassic source rocks of Western Siberia and a number of basins in China shows the similarity of their organic matter. The hydrocarbon generation potential of the organic matter of the Middle Jurassic coals and their analogues can be realized in the sedimentary basins of Mongolia.

Twelve hydrothermal autoclave experiments were conducted with Domanik oil shale from the Ukhta region (Chut River) at temperatures of 250–375°C and run duration of 24 h (6 experiments), 72 h (5 experiments), and 48 h (1 experiment). The composition of hydrocarbon gases C1–C5 was studied for each experiment and quantitative data on their yields were obtained. Based on these data, the distributions of generation potential of individual gaseous hydrocarbons by activation energy were established under hydrothermal experimental conditions. The character of the kinetic spectra of individual alkanes C2–C5 is virtually identical; their main narrow maximum corresponds to Ea 55 kcal/mol with an Arrhenius factor of 1 × 1014 s–1. The distribution of the methane generation potential by activation energies is distinguished by the fact that a significant part of its generation potential falls within the region of activation energies of 60–70 kcal/mol and by the uncertainty of the distribution character in this region.

The objects of study were bitumens of sedimentary rocks and paraffin oils of the Middle Devonian-lower Frasnian terrigenous complex of the Timan-Pechora basin. We studied the composition of biomarker hydrocarbons and the carbon isotope composition of individual n-alkanes of bitumens from the cores of the wells of the Omra-Lyzha saddle. The results were compared with similar data on the composition of paraffin oils from the south of the Pechora-Kozhva megaswell. The generation potential and thermal maturity of organic matter were studied by the Rock-Eval pyrolysis method. The maturity of organic matter in the rocks of the studied complex in the Omra-Lyzha saddle and the Pechora-Kozhva megaswell corresponds to the oil window. Data on the carbon isotopy of n-alkanes and on the composition of biomarker hydrocarbons do not contradict the possible genetic relationship between paraffin oils and the organic matter of the host sedimentary complex. Both the studied paraffin oils and the rock bitumens contain early eluting rearranged hopanes atypical of oils of other petroliferous complexes and show high contents of n-alkanes relative to iso-alkanes and polycyclic biomarkers. The content of 13C tends to decrease with an increase in the number of carbon atoms in the n-alkane molecule in both oils and bitumen rocks.

A series of kerogen samples were isolated from Domanik oil shale before and after hydrothermal treatment in an autoclave (at 250–375°C, for 24 h). Than composition of the C1–C5 hydrocarbon gases generated in stepwise (300–800°C) pyrolysis of these kerogens was characterized by gas chromatography. According to the calculated EASY

—The composition of the oldest coals of the Timan–northern Urals region has been studied comprehensively, and their hydrocarbon and microcomponent characteristics are given. The relationship between different types of coals and Late Devonian plant communities of the North Timan is revealed. It is also determined that some samples contain microspores, megaspores, and plant remains belonging mainly to the lycopod Helenia. The most probable source of jet coals is identified as the wood of the progymnosperm Callixylon. The values of vitrinite reflectance and Tmax and the data on the distribution of polycyclic biomarkers and methylphenanthrenes indicate the low maturation of the coal organic matter. The coal bitumen investigated here is characterized by the dominance of steranes and diaster-13(17)-enes of compositions C28 and C29. The following diterpanes are identified: beyerane, 16α(H)-kaurane, 16β(H)-kaurane, and 16α(H)-atisane. At the same time, phyllocladane is absent.

Ashless extracts, hypercoals, were obtained from Tuvan coals of the Ulug-Khem basin by dissolving them in N-methylpyrrolidone. The yield of the extracts was 27.3–79.4

This study focuses on the composition of the adhesives used to repair clay vessels, and on the technique of their preparation in the Late Neolithic and Chalcolithic (late 4th to early 3rd millennia BC) sites of Far Northeast Europe (the Republic of Komi and the Nenets Autonomous Okrug). Remains of adhesives were detected on 70 of 171 repaired pots. To date, five samples of ceramics from dwellings of the Chuzhyael culture have been analyzed. Gas chromatography-mass spectrometry revealed no markers of coniferous trees or bitumen; but did reveal markers of birch, suggesting that fractures and cracks on broken pots were plastered with birch tar. The composition of organic compounds in samples indicates the use of two vessels in the technological process: in one of them, birch bark was subjected to pyrolysis, while the other was a receptacle for tar. This comparatively complex technology reveals one more specialization in the domestic manufacture of the taiga hunter-gatherers, including the use of special furnaces. Analytic procedures employed by us open up new prospects for the study of the material culture of Far Northeast Europe, extend our knowledge of domestic manufacture, and offer new material for AMS dating.

Комплексно исследован состав древнейших углей Тимано-Североуральского региона, приводятся сведенья об их углеводородном и микрокомпонентном составе. Показана связь углей с определёнными растительными сообществами позднего девона Северного Тимана. В ряде образцов выявлено присутствие микро- и мегаспор и остатков растений, относящихся преимущественно к плауновидным рода Helenia; образование гагатов связывается с древесиной археоптерисовых, относимых к роду Callixylon. Значения отражательной способности витринита и показатели Tmax, а также данные о распределении полициклических биомаркеров и метилфенантренов указывают на невысокий катагенез органического вещества углей. Для битумоида исследованных углей характерно доминирование стеранов и диастер-13(17)-енов состава С28 и С29. Идентифицированы дитерпаны: биеран, 16α(H)-кауран и 16β(H)-кауран и 16α(H)-атисан при отсутствии филокладана. The composition of the oldest coals of the Timan–northern Urals region has been studied comprehensively, and their hydrocarbon and microcomponent characteristics are given. The relationship between different types of coals and Late Devonian plant communities of the North Timan is revealed. It is also determined that some samples contain microspores, megaspores, and plant remains belonging mainly to the lycopod Helenia. The most probable source of jet coals is identified as the wood of the progymnosperm Callixylon. The values of vitrinite reflectance and Tmax and the data on the distribution of polycyclic biomarkers and methylphenanthrenes indicate the low maturation of the coal organic matter. The coal bitumen investigated here is characterized by the dominance of steranes and diaster-13(17)-enes of compositions С28 и С29. The following diterpanes are identified: beyerane, 16α(H)-kaurane, 16β(H)-kaurane, and 16α(H)-atisane. At the same time, phyllocladane is absent.

The composition of biomarker hydrocarbons in crude oil samples from Middle Devonian deposits of the Western Tebuk, Dzh”er, and Michayu oil fields of the Omra–Lyzha saddle in the Timan–Pechora oil-and-gas province was studied. Significant effect of the Upper Devonian Domanik source rocks on the formation of the composition of these crude oils was revealed. The main parameters demonstrating the genetic relationship of the oils from Middle Devonian reservoirs with this source rocks are distribution of steranes С 27 : С 28 : С 29 , ratio of isoprenoid to normal alkanes, and distribution of normal alkanes. All these characteristics sharply distinguish the crude oils under consideration from paraffinous oils syngenetic to Middle Devonian deposits, characteristic of deposits in the southern part of the Pechora–Kozhva megarampart.

This is a retrospective review of existing knowledge and major research areas related to the structure of asphaltenes and their applicability in petroleum and organic geochemistry. The paper emphasizes the great potential of the current analytic base for further research into the structural elements, functional groups, and intermolecular interaction mechanisms of asphaltenes from crude oils, natural bitumens, and sedimentary rock extracts. The principal methods for investigating the composition and structure of asphaltenes are described from the perspective of solving the pressing challenges of organic geochemistry. Geochemical interpretation of the chemical and supramolecular structures of asphaltenes provides valuable information in addition to the data on the structural elements of asphaltenes and their binding modes. Accumulation of relevant data on the molecular and supramolecular structures of asphaltenes is of considerable importance for a deeper understanding of their behaviors and for unraveling the correlations between crude oils and precursor sedimentary organic matter.

—It has been established that the average values of some hydrocarbons biomarker coefficients of bitumens from the Domanik deposits and oils from the Domanik–Tournaisian complex coincide. These are the proportions of C 27 –C 29 steranes, tri-/pentacyclanes ratio, and coefficients 2 × С 17 /С 16 + С 18 and 2 × С 27 /С 26 + С 28 calculated from n -alkane composition. Such indicators as the Pr/Ph, (Pr + Ph)/( n ‑C 17 + n ‑C 18 ), dia-/reg-steranes, and the sterane/hopane ratios in oils are slightly lower than in the bitumen. The average values of δ 13 C in asphaltene, resin, aromatic hydrocarbons, and aliphatic hydrocarbons fractions from oils of the Domanik genotype and in the studied bitumens are similar. The carbon isotope composition of asphaltenes in oils is depleted in 13 С compared to those of resins and aromatic hydrocarbons, and vice versa in bitumens. A heterogeneous composition of the bacterial flora in the sediments of the Domanik Sea is suggested. In some places, species with high concentrations of diplopterol or hexafunctional bacteriohopanes likely dominated over bacteriohopantetrol.

The composition of hydrocarbon gases formed by pyrolysis of residual Domanik shale kerogen at 800°C, preceded by hydrothermal treatment at 250–375°С, was studied by pyrolytic gas chromatography. Starting from the autoclave temperature of 320–325°C, the hydrothermal treatment of the shale affects the kerogen structures responsible for the formation of C 2+ gases in pyrolysis at 800°C. An increase in the temperature of the shale hydrothermal treatment leads to a monotonic increase in the С 1 /С 2+ ratio in the products of the residual kerogen pyrolysis at 800°C. The methane yield at 800°C does not correlate with the content of alkyl structures, determined in kerogen by IR spectroscopy, and the yield of С 2+ gases linearly correlates with the content of alkyl structures.

Mumijo is a product of natural origin, composed of a complex mixture of organic compounds and exhibiting physiological activity in some cases. The Altai mumijo is widely known in Russia, but Tuvinian mumijo has been studied much less. The data on the location of mumijo in the Republic of Tyva, its elemental composition, isotopic composition of carbon, amino acid spectrum, and mineral formations associated with mumijo are presented. The investigated mumijo is a waste product of small rodents, which underwent aqua transfer, weathering and bacterial processing.

The paper presents original data on the composition of hydrocarbon biomarkers and the carbon isotope composition of fractions of some oils in the Middle Devonian–lower Frasnian terrigenous rock complex in the Timan–Pechora basin. The oils typically contain high concentrations of paraffin hydrocarbons. The oils of hydrocarbon systems were generated at the catagenesis of terrigenous organic matter in the host rocks. The complex of hydrocarbon biomarkers of the oils shows features indicating that the paraffin-rich dominant component of the oils mixed with oils from other hydrocarbon systems, namely, from the Domanik–Tournaisian and Lower Paleozoic carbonate rock complexes.

The results of geochemical studies concerning oils from Permian and Carboniferous fields of the Sorokin swell of the Varandey-Adzva structural zone of the Timan-Pechora petroleum province are presented. The reservoirs represented by carbonate of Carboniferous and Lower Permian age are characterized by good and medium reservoir properties - the type of reservoirs is mainly fractured- and secondary- pore. Based on our data, it was found that the oils were formed in the parent carbonate-clay strata with a significant contribution of algal source organic matter. It is likely that the Visean-age oil is generated by Silurian-Lower Devonian strata. The thermal maturity of the oils corresponds to the MK2 gradation of the transformation of the rocks organic matter.

The hydrocarbon composition of oils from the Ordovician-Lower Devonian carbonate oil and gas complex in the northern part of the Timan-Pechora province has been studied. According to the composition of normal alkanes, the studied oils are confidently divided into two groups. The first group is characterized by the dominance of the C17 homologue among n-alkanes, which is characteristic of the organic matter of marine carbonates, and the second group is characterized by C17 and C19 predominance with a sharp decrease in the content of C20+ n-alkanes (which is a sign of a special OM of marine carbonates – algae G Prisca). Genetic indicators determined by the distribution of polycyclic biomarkers, for example, the ratio of αββ steranes of the composition С27:С28:С29, also indicate that oils of types I and II have a slightly different composition of the initial OM, but are characterized by close conditions of sedimentation of the initial OM, which occurred in shallow sea environments. The indicators of thermal maturity make it possible to attribute the studied oils to the peak of oil window. It is probable that the generation of oils occurred in rocks whose organic matter reached the catagenesis grade MK2. Data for polycyclic biomarkers give slightly lower maturity scores than those for aromatic (phenanthrenes and dibenzothiophenes) compounds.

The relevance. Hard coals of the Mezhegey deposit are used mainly as a sintering additive for coke production. However, the heterogeneity and multicomponent nature of coal composition make it possible to consider coal as a raw material for deep chemical processing and as a carrier of valuable metals in various concentrations, and a coal seam as a coal-gas deposit. Such an integrated approach to the development of fossil fuels requires research from various positions on the features of organic and inorganic matter, which depend on the initial conditions of accumulation and sources of matter. The purpose: to study the composition of Middle Jurassic coals organic matter in the Mezhegey deposit of the Ulug-Khem coal basin in a complex of coal-petrographic and organic geochemical research methods. Methods: microscopic study of maceral composition in thin sections in transmitted light. Analytical moisture content and ash content were determined by standardized methods. Geochemical studies included the extraction of chloroform bitumoid from coals, fractionation of the obtained extract, gas chromatographic and chromato-mass spectrometric analysis of the aliphatic and aromatic bitumoid fractions. Based on the obtained data indices characterizing the conditions of accumulation of organic matter, its possible sources, and the degree of thermal transformation were calculated. Results of petrographic and geochemical studies of Middle Jurassic coals of the Mezhegey deposit of the Ulug-Khem basin show that their microcomponent composition is almost monomaceral with a predominance of structureless vitrinite. Coals were formed on the periphery of a large lake, possibly periodically connected with. sea, under conditions close to marsh. The composition and distribution of alkanes, steranes, and hopanes in the aliphatic fraction of biutmoid were studied. Distribution of n-alkanes and isoprenoids indicates the formation of coals mainly from the remains of aquatic vegetation with some participation of humic matter. The significant contribution of higher terrestrial vegetation is also confirmed by the distribution of C-27, C-28, C-29 steranes. Values of carbon preference index of alkanes, the known ratios of steranes and hopanes isomers and aromatic hudrocarbons testify to the high maturity of the coal organic matter.

—A comprehensive study of Domanik deposits of the Timan–Pechora Basin has been carried out. The examined composition of hydrocarbon biomarkers, chemical structure of kerogen, carbon isotope composition, and rock lithology, the Rock-Eval pyrolysis data, and the contents of bitumen and Corg in the rocks give an insight into the geochemical processes in the oil window in the Domanik deposits, which took place at Tmax = 435–450 °C. The bitumen coefficient βCB is maximum in this temperature interval, reaching 30%. The obtained data on the distribution of polycyclic biomarkers in the Domanik rocks and the bitumen and Rock-Eval pyrolysis data allowed determining the boundary values of biomarker maturity coefficients in the study of the maturation of organic matter of the rocks. The carbon isotope composition of bitumen fractions in the Domanik rocks is considered, and the bimodal distribution of the δ13C values of the bitumen is shown.