Merkulov O.I., Afanasenko A.P., Moskovsky I.G., Glukhova E.V. 1. JSC «Rosgeology», Moscow, Russia
2. JSC «Nizhne-Volzhsky Scientific Research Institute of Geology and Geophysics», Saratov, Russia
Keywords: hydrocarbons, hydrocarbon system modeling, geochemistry, hydrocarbon generation, compositional kinetic spectra, oil and gas source rocks, hydrocarbon potential, chromatography, pyrolysis
This article presents the fundamental principles of the author's technology for the justification and reconstruction of compositional kinetic spectra GeoArrhenius/SpectrOptim. The advantage of this technology lies in its ability to confidently separate gaseous hydrocarbons on the chromatogram and reconstruct multi-component (with an arbitrary number of components) kinetic spectra at the onset of catagenesis based on neural network modeling. Utilizing this technology in modeling hydrocarbon systems allows for accurate assessments of the volumes of hydrocarbons generated by the oil and gas source rock, and consequently, enables the evaluation of hydrocarbon resources in the area of study. This approach reduces the reliance on external and internal analogs during calculations, as well as the expert opinions of geological researchers.
U.A. Moroz1, A.V. Nikiforov1, V.V. Yarmolyuk1,2, A.M. Kozlovsky1, A.A. Ivanova3, E.V. Salnikova3, V.M. Savatenkov3, U.V. Plotkina3, А.К. Khertek2, N.A. Polyakov1 1 Institute of Geology and Ore Deposits, Petrography, Mineralogy and Geochemistry, Russian Academy of Sciences, Russia 2 Tuvinian Institute for Exploration of Natural Resources of Siberian Branch of the Russian Academy of Sciences, Kyzyl, Russia 3 Institute of Precambrian Geology and Geochronology, Russian Academy of Sciences, St. Petersburg, Russia
Keywords: nepheline syenites, Central Asian Orogenic Belt, magma differentiation, isotopic composition, geochronology, Sangilen, rare-metal magmatism.
Massifs of alkaline granitoids and nepheline syenites are quite widespread in the territory of Eastern Tuva. Rare metal deposits and ore occurrences, which were formed mainly at the end of the Carboniferous period and in the Permian, are often associated with them. The Naryn massif includes nepheline syenites of the main phase, contact zone and a complex of 3 types of foidite microsyenite dikes. The age of the massif determined by zircon from the rocks of the main phase (SIMS – 315±3 million years) and dikes of microsyenites-1 (CA ID TIMS – 318±1 million years) showed an earlier time of its formation in the middle of the Carboniferous. Mineralogical, geochemical and Nd-isotope characteristics of the massif rocks suggest that the diversity of its rocks is associated with the same type of differentiation of a single initial magma, but occurring at different hypsometric levels. Crystallization of biotite-pyroxene-amphibole nepheline syenites of the main phase and feldspar liebnerite syenites of the marginal zone occurred at the upper level. From the lower chamber with the differentiating melt, dykes of apo-amphibole nepheline microsyenites-1, pyroxene-biotite microsyenites-2 and biotite nepheline microsyenites-3 were successively intruded. The evolution of melts, both at the upper and lower levels, occurred due to the precipitation of mafic minerals (amphibole), apatite and feldspar. With an increase in the alkalinity of the melts, accumulation of rare elements (Zr, Nb, Ta, REE) occurred, which are included in their own minerals at the late stages of rock crystallization. These data indicate that the foidite series rocks, widespread in Eastern Tuva, may be potentially ore-bearing, and the middle of the Carboniferous period should be considered as a phase of alkaline magmatism of the East Sayan rare-metal metallogenic zone. The Nd isotopic composition of the Naryn massif rocks (Nd(T) +6.3 – +7.1) does not suggest significant participation of the continental crust in the source of melts, therefore, sublithospheric alkaline-basaltoid magmas probably served as parental rocks for all the Naryn massif rocks.
Using a model sample of pyrite ore collected at the Degdekan gold deposit (North East Russia), we demonstrate the use of different variants of the IСP-MS method to determine the ratio of surficial-bound and structural-bound forms of trace elements (TE) in pyrite. Despite the difference in the physicochemical nature of the analysis methods involving the decomposition of crystals of different sizes (analytical data selections for single crystals - ADSSC) and direct determination by scanning the surface with a laser beam of different power (LA-IСP-MS), it has been shown that a number of elements tend to enrich the surface layer of pyrite crystals. The ratio of TE contents in the surface layer and in the volume (structure) of the crystal is defined as the selectivity (S) of surficial phases in the uptake of a given element. According to ICP MS – ADSSC data, the selectivity was 3.9 (Mn), 3.3 (Ag), 6.4 (Pd), 6.4 (La), 0.3 (Pr), 0.8 (Tb), 2.6 (Ho), 0.5 (Er), 1.0 (Lu), according to the results of LA-ICP-MS 3.9 (Mn), 1.4 (Co), 6.2 (Ni), 1.6 (Cu), 0.9 (Sb), 0.2 (Au), 0.3 (As), 6.8 (Ag), 18 (La), 46 (Ce), 5.2 (Pr), 11 (Nd), 1 (Eu), 0.6 (Dy). A comparison with experimental data for S Mn, Pd, and Ag reveals comparable results. However, it is concluded that LA-IСP-MS should be more representative in order to enable criterion-based statistical sampling (CBSS) according to a principle similar to ADSSC for more accurate discrimination of the structural component of TE concentration. Otherwise, significant errors are possible due to the influence of microinclusions of autonomous phases, in this case galena, which concentrates As, Au and Sb due to heterovalent isomorphism, resulting in S<1 for these elements. Most of the studied TEs show a direct correlation between selectivity and the difference in the ionic radii of the element and Fe, which confirms the relationship between S and the level of incompatibility of the impurity element in FeS2. High correlation coefficients between light REEs in the surface and the absence or negative correlations between light and heavy REEs are noted. This may reflect differences in the species of heavy and light lanthanides and requires more detailed study using LA-ICP-MS surface analysis and the application of the CBSS procedure. Despite the preliminary nature of the results, they deserve attention in practical terms as a justification for the development of technology for the extraction of critically important REEs as by-products in the processing and enrichment of pyrite ores and concentrates. They also justify the importance of the surface accumulation effect of REEs and the need to take it into account in meta-analysis and statistical processing of the results of analytical determinations of element content.
This paper describes a system for monitoring seismicity in specific volcanic areas of Kamchatka (Russia, Kamchatka Peninsula) based on estimates of the seismicity level according to the SESL’09 (Statistical Estimation of Seismicity Level) methodology. The application of the SESL’09 method to studying the preparation of volcanic activations is a promising approach for monitoring volcano state. We present the results of identifying seismically active source volumes for 10 active Kamchatka volcanoes. Nomograms were constructed for these volumes, allowing for the estimation of the seismicity level for any given time interval based on the seismic energy released within it. Examples of variations in the seismicity level of the volcanic areas, which are associated with the preparation for an eruption, are provided and support this conclusion.
A.V. Degterev¹, S.Z. Smirnov², D.V. Kuzmin², T.Yu. Timina², A.Ya. Shevko², I.R. Nizametdinov², F.A. Romanyuk¹, M.V. Chibisova¹ 1Institute of Marine Geology and Geophysics, Far Eastern Branch of the Russian Academy of Sciences, Yuzhno-Sakhalinsk, Russia
2V.S. Sobolev Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia
Keywords: Kuril Islands, Iturup Island, caldera, Lvinaya Past, pyroclastic deposits, explosive eruptions, pyroclastic flows, tephra, radiocarbon dating, geochemistry
At the end of the Pleistocene, two large-scale volcanic eruptions, associated with the formation of the Lvinaya Past caldera, occurred in the southern part of Iturup Island (Southern Kurils). These eruptions resulted in the formation of the largest partially submerged caldera in the Kuril Island arc, measuring 7×9 km, with a rim area of ~50 km² and a volume of ~25 km³ (including a submarine part of 12.26 km³). Comprehensive geological and geochronological studies established that the caldera formation was associated with two successive, very powerful explosive eruptions (LP-I and LP-II), separated by a repose period of several hundred years. The age of the first eruption (LP-I) is likely about 13,500 cal yr BP. The age of the second eruption (LP-II), determined from a series of radiocarbon dates, is estimated at ~12,300 cal yr BP. The eruptions were of Plinian type and involved the massive ejection of silicic pyroclastic material, represented by pyroclastic flow deposits and tephra. Based on silica and total alkali contents, the pumice from the caldera-forming eruption corresponds to low-alkali dacites and rhyodacites (SiO₂ 63.4–69.95 wt.%, total alkalis 3.9–5.5 wt.%), with less frequent andesitic (SiO₂ 58.3 wt.%, total alkalis 3 wt.%) and rhyolitic compositions (SiO₂ ~74 wt.%, total alkalis 5.6 wt.%). The total volume of erupted material from both events is preliminarily estimated at 80–100 km³ (DRE 35–45 km³), with the LP-II eruption being 30–40% more powerful than LP-I. It is suggested that the LP-I and LP-II eruptions, occurring only a few hundred years apart, could have impacted the natural environment on a regional and possibly global scale.
When conducting seismic surveys on the ground, it is usually not possible to place receivers with a uniform sufficiently frequent step over the area of observation. Interpolation (regularization) is an effective tool for generating additional seismic records without changing the spectral composition of data over time and with expansion of the spectral composition over space. This paper considers the optimization of a regularization algorithm based on iterative application of discrete Fourier transform (DPF) over a space known as ALFT (Anti-leakage Fourier transform). The proposed modification of ALFT is a way to reduce the set of test wave numbers when performing DPF. The effectiveness of the proposed algorithm was confirmed by processing both synthetic and field data. The calculation time has been reduced by several times compared to the original algorithm, and the results of recovery of skipped routes have not deteriorated. The results are valuable from a practical point of view and can be applied in future to the processing of ground-based seismic data on an industrial scale.
N.A. Mukhortina, E. V. Zippa 1Tomsk Branch of Trofimuk Institute of Petroleum Geology and Geophysics of Siberian Branch Russian Academy of Sciences, Tomsk, Russia
Keywords: polycyclic aromatic hydrocarbons, thermal waters, genesis of PAHs, technogenic load, water-rock system
New data on the composition and distribution of polycyclic aromatic hydrocarbons (PAHС) in thermal waters and host rocks in Baikal Rift Zone were obtained. It was shown that the total content of all identified individual compounds is 0.17-1.15 μg/L in the thermal springs and is 0.021-1.19 μg/kg in the rock. Naphthalene, phenanthrene, and dibenzo[a,h]anthracene dominate in the water. Phenanthrene, fluoranthene, and dibenzo[a,h]anthracene are predominant in the rock. The total PAHC content increased with TDS of water and with N2 and He growth in escaped gases. The calculated coefficients of technogenic load showed a low level of pollution for all studied sources. According to indicator ratios, the PAHC origin was determined. On the one hand, PAHC in thermal waters had petrogenic origin and were formed due to geochemical transformations of organic matter under high temperatures and pressures and microbial activity, entered with aqueous and gas along faults and fractures. On the other hand, some compounds have a natural pyrogenic origin, where pyrolysis products enter springs either at near-surface conditions or when mixing. The results let to characterize the composition of thermal waters in more detail and to describe a conceptual model the thermal waters composition formation in the studied region.
A. V. Drakon, A. V. Eremin, R. N. Kolotushkin, E. Yu. Mikheeva, E. S. Khodyko
Joint Institute for High Temperatures, Russian Academy of Sciences, Moscow, Russia
Keywords: soot formation, soot particles, flat flame, LII, ethylene combustion, DME
The article presents experimental and calculated results of a study of the formation and growth of soot particles in a standard ethylene/air flat flame with dimethyl ether (DME) additive. Two-dimensional laser-induced incandescence (2D-LII) was used as an experimental method, obtaining data on the volume fraction of soot particles in the flame. The time-resolved LII signal provided information on the average soot particle size depending on the flame height. Kinetic modeling was performed using a modern kinetic mechanism of hydrocarbon pyrolysis and oxidation, including a sectional model of soot particle growth. It was shown that DME additives lead to a decrease in soot yield without significantly affecting the final particle size. Furthermore, DME additives slow down the initial stages of soot particle formation but accelerate their subsequent growth.
E. M. Makaryan, S. D. Arsentyev, M. Dzh. Pogosyan
Nalbandyan Institute of Chemical Physics, National Academy of Sciences of Armenia, Yerevan, Armenia
Keywords: chain reactions, methane oxidation, peroxide radicals
The mechanism of chain development during thermal gas-phase oxidation of methane was studied experimentally and theoretically. It was found that the rate-limiting step, which determines the overall process development, depends on the conditions. At a temperature of 728 K, the process is determined by the interaction of peroxide radicals with each other. Increasing the temperature to 873 K leads to an increased role for the reactions of peroxide radicals with formaldehyde, after which the rate-limiting step becomes the interaction of peroxide radicals with methane. Furthermore, changes in pressure and temperature have an equal effect on the concentration ratio of hydroperoxide and methylperoxide radicals, determined both by calculation and experiment.
A. M. Savelyev, V. A. Savelyeva, A. N. Tarasenko, S. A. Torokhov, I. N. Kadochnikov, D. V. Novakovsky
Baranov Central Institute of Aviation Motors, Moscow, Russia
Keywords: low-emission combustion, combustion chamber, modeling, surrogates
A skeletal reaction mechanism for the ignition and combustion of complex dodecane/decane/isooctane/isocetane/toluene surrogates of kerosene-type aviation fuels has been developed. The mechanism includes submechanisms for the oxidation of dodecane, decane, isooctane, isocetane, and toluene in the high- and low-temperature regions, as well as in the inverse temperature coefficient zone. The mechanism was tested using experimental data on ignition delay time, normal flame propagation velocity, and component concentration distribution. The combustion characteristics of the surrogates were tested using the developed reaction mechanism, and a demonstration CFD simulation of the operating process in a low-emission combustor of a gas turbine engine using rich-lean combustion technology was conducted.
