Russian Geology and Geophysics最新文献

{"title":"A Method for Correction of Shoulder-Bed Effect on Resistivity Logs Based on a Convolutional Neural Network","authors":"A. Leonenko, A. M. Petrov, K. Danilovskiy","doi":"10.2113/rgg20234531","DOIUrl":"https://doi.org/10.2113/rgg20234531","url":null,"abstract":"\u0000 —Shoulder beds may have a significant effect on the resistivity log responses. This problem is especially acute in studies of complex strata composed of thin beds with contrasting properties. Different approaches to taking account of the shoulder-bed effect on logging signals are known, such as correction charts, deconvolution operations, and using advanced algorithms of numerical data inversion, which allow one to consider the vertical inhomogeneity of the section. The best result is achieved using the inversion toolkit, but the high labor- and resource-intensiveness of the approach limits its widespread use. The deconvolution approach does not have these disadvantages, but it does not take into account the influence of radial changes in the medium properties on the shapes of measured signals.The possibility of using artificial neural networks (ANN) to increase the vertical resolution of the measured logging data is explored. We assume the existence of a deconvolution-like transformation in which change in the medium properties in the radial direction is also considered. In this case, we can find its approximation using a neural network. The approach is demonstrated by creating a transformation algorithm for the high-frequency electromagnetic logging (VIKIZ) sounding tool, which is widely used in the CIS countries for petroleum exploration. The developed algorithm has been tested on the VIKIZ logs from the Fedorovskoe oilfield (Latitudinal Ob’ region).","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45492657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental Modeling of the Mantle–Slab Interaction in the Metal–Carbonate System, Conditions of Crystallization and Indicator Characteristics of Diamond","authors":"Y. Palyanov, Y. Bataleva, Yury M. Borzdov, I. Kupriyanov, D. V. Nechaev","doi":"10.2113/rgg20234559","DOIUrl":"https://doi.org/10.2113/rgg20234559","url":null,"abstract":"\u0000 —Experimental studies aimed at determining the conditions for the formation of diamond and graphite as a result of the redox interaction of reduced mantle rocks and oxidized rocks of the slab in a wide temperature range, including the conditions of both “cold” and “hot” subduction, were carried out on a “split-sphere” multianvil high-pressure apparatus (BARS) in the (Fe,Ni)–(Mg,Ca)CO3 system, at 6.3 GPa and 800–1550 °C for 35–105 h, using the “sandwich” assembly. We have established that the interaction of Fe,Ni metal and carbonate is due to the creation and propagation of a redox front, at rates from 1.3 (800 °C) to 118 μm/h (1550 °C). At T < 1200 °С, this interaction leads to the formation of alternating reaction zones (from the reduced center to the oxidized periphery): metal → metal + wüstite/magnesiowüstite → magnesiowüstite + graphite ± Mg,Fe,Ca carbonates → magnesite + aragonite. In this case, in the reduced part of the samples, the formation of a Ni,Fe metal phase strongly enriched in Ni (up to 65–70 wt.% vs. the initial 10 wt.%) was recorded. At higher temperatures, the formation of Fe,Ni metal–carbon (≥1200 °C) and carbonate (≥1330 °C) melts was observed. We have found that the presence of nickel precludes the formation of carbides in the reduced part of the sample and ensures stable diamond crystallization at 1400–1550 °C both in metal–carbon and carbonate melts. Our experiments demonstrate that diamonds from the metal–carbon melt are characterized by inclusions of taenite and magnesiowüstite. The morphology of these diamonds is determined by the {111} layer-by-layer grown faces, and their indicator characteristics are nitrogen–vacancy and nickel-related (884 nm) centers at 1400 °C or nickel–nitrogen centers (S3, 598 nm, 727 nm, 746 nm, etc.) at 1550 °C. For diamonds formed in the carbonate melt, the morphology is determined by the {100} and {111} (vicinal-growth) faces; carbonates are identified as inclusions; and nitrogen–vacancy centers H3, NV0, and NV– are fixed in the photoluminescence spectra. Experiments show that the indicator of the metal–carbonate interaction temperature is the degree of structural perfection of graphite, which increases in the range of 800–1550 °C.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46845151","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical Inversion of the Sumudu Integral Transform in the Simulation of Electromagnetic Sounding of the Earth’s Interior","authors":"M. Epov, О.V. Nechaev, V. Glinskikh","doi":"10.2113/rgg20234537","DOIUrl":"https://doi.org/10.2113/rgg20234537","url":null,"abstract":"\u0000 ––The integral Sumudu transform was established as an alternative to the Laplace transform in the 1990s. The Sumudu transform fundamental properties include preservation of the dimensionality of a function, ensuring measurement units both in the function and its image to be equivalent. Among its disadvantages is the absence of an explicit formula for calculating the inverse transform. The transforms are inverted by solving the corresponding Fredholm integral equation of the first kind, which is reduced to solving an ill-conditioned system of linear algebraic equations. We apply Tikhonov’s method for regularization of this type system. The paper proposes a technique for constructing a parametrized regularizing matrix that takes into account the properties of the Sumudu images obtained by modeling the electromagnetic sounding process of the Earth’s interior. A method for choosing the Tikhonov regularization parameters and the regularizing matrix is considered. The effectiveness of the proposed method for the Sumudu transform inversion is examined on a model problem of electromagnetic sounding of the Earth’s interior by a measurement system consisting of two loops spaced apart.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41871827","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phase Transformations in Feldspar Group Minerals with Paracelsian Topology under High Temperature and High Pressure","authors":"L. Gorelova","doi":"10.2113/rgg20234557","DOIUrl":"https://doi.org/10.2113/rgg20234557","url":null,"abstract":"\u0000 —Feldspar group minerals (feldspars) form up to 60 vol.% of the Earth’s crust. The knowledge of their stability under extreme conditions (high-pressure and high-temperature) allow to better understand the processes, that occur in the subduction and collision processes. This review focuses on the behavior of feldspars with paracelsian topology (seven mineral species: three borosilicates, two aluminosilicates and two beryllophosphates) at elevated temperatures and pressures. Partly, new data on high-temperature behavior of paracelsian BaAl2Si2O8 (based on in situ high-temperature powder X-ray diffraction) provided. The high-temperature studies of 5 feldspar minerals with paracelsian topology (danburite, maleevite, pekovite, paracelsian, slawsonite) revealed that all of them are stable at least up to 800 °C. Among all of them only paracelsian undergoes polymorphic transition (at 930 °C), whereas all other minerals decompose or amorphisize. The structural deformations of these minerals demonstrate the different anisotropy degree upon heating, whereas the average volume expansion is similar for all of them (αV = 23 × 10–6 ºC–1). High-pressure behavior was studied for six of seven minerals with paracelsian topology (danburite, meleevite, pekovite, paracelsian, slawsonite, hurlbutite). The studied minerals undergo transformations with the stepwise increasing of coordination number of frame-forming cations from 4 to 5 and 6 upon compression The discovering of unusual structural units under extreme conditions (e.g., fivefold-coordinated polyhedral) can influence on the concentration and transport processes of trace elements that should be taken into account when interpreting geochemical and geophysical data. The crystal structure stability range of studied minerals highly depends on the chemical composition of frame-forming cations: aluminosilicates are the least stable and undergo the phase transitions below 6 GPa; borosilicates preserve their initial crystal structure up to ~20 GPa; beryllium phosphates do not undergo phase 2 transformations up to 75 GPa. It has been shown that transformations pathway of isostuctural compounds highly depends on the chemical composition of both extraframework and frame-forming cations that involves the difficulties with predictions of their behavior under extreme conditions.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49153611","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ordovician Stratigraphy, Facies, Deposition Environments, Faunas, Ichnofossils, and Paleogeography of Central Tyva","authors":"N. Sennikov","doi":"10.2113/rgg20234550","DOIUrl":"https://doi.org/10.2113/rgg20234550","url":null,"abstract":"\u0000 ––A large regional-scale Ordovician continental basin has been revealed for the first time in Siberia. Sedimentary structures in the Ordovician rocks of Tyva represent deposition environments of rivers, oxbow lakes, dunes, river deltas, tidal, and coastal plains. Ichnofossils record a succession from freshwater (limnic-fluvial) to deltaic and tidal facies. Integrated studies of sedimentary rocks from Central Tyva show that they were deposited on a coastal plain within a large river delta. The Central Tyva Ordovician basin was similar to the coeval basins of the Gondwanian continents in the style of clastic and redbed deposition.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41507503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical Elements Concentration, Variations in Mineral Composition, and Current Rate of Sedimentation in Sapropel Deposits of Small Lakes in the Taiga Zone of Southern Siberia","authors":"V. Strakhovenko, E. Ovdina, V. Malov, G. Malov","doi":"10.2113/rgg20234526","DOIUrl":"https://doi.org/10.2113/rgg20234526","url":null,"abstract":"\u0000 ––We studied the bottom sediments of lake systems located in the taiga landscape of Siberia. In the south of Western Siberia, there are 11 lakes in the subzone of the south taiga and 9 lakes in the subtaiga subzone. On the territory of the south of Eastern Siberia in the taiga zone there are 10 lakes on the southern coast of Lake Baikal, 5 lakes on its east coast and 6 lakes are located on the territory of the national park “Alkhanai” in Transbaikalia. Studies of the chemical composition of water, soil, and sediment samples were conducted at the Analytical Center for Multi-Elemental and Isotope Research SB RAS, Novosibirsk. The use of a complex of modern analytical methods in the study of the same lake samples made it possible to obtain more reliable information (1861 samples of bottom sediment were studied). Quartz and feldspars of pelitic dimension dominate in the mineral composition of the terrigenous fraction, organic matter and authigenic minerals (opal, pyrite, illite and sometimes calcite) are added to them during the bottom sediments formation. The absolute contents of the studied elements in the bottom sediments of all lakes are lower than their concentrations in the upper continental crust and sedimentary rocks of the Russian Plate, with the exception of Si, Hg, Cd. In the lakes of the subtaiga of the south of Western Siberia, an exception was established for Ca in the bottom sediments of which carbonates predominate. Contents variations of a number of elements in the bottom sediments of taiga lakes in different regions do not significantly differ. The dispersion of their concentrations between lakes with a total catchment area and lakes from different regions are comparable (Ca, Sr, Al, Mn, Fe, Cd, Hg, etc.). The current sedimentation rate in natural occurrence in the lakes of the taiga zone (southern Siberia) vary from 1.1 to 2.9 mm/year. Moreover, it is comparable to the current sedimentation rate in the lakes of the forest-steppe and steppe zones of south of Western Siberia.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44696605","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lithological and Geochemical Indicators of Ice Gouging: Evidences from Holocene Sediments in the East Siberian Sea","authors":"А.V. Alatortsev, А.N. Kolesnik, X. Shi, L. Hu, V. Karnaukh, А.S. Astakhov","doi":"10.2113/rgg20234528","DOIUrl":"https://doi.org/10.2113/rgg20234528","url":null,"abstract":"\u0000 ––Cores of Holocene bottom sediment collected in the East Siberian Sea revealed layers with mixed textures and layers with breaks in sedimentation corresponding to the two sea levels defined as modern (upper) and Early Holocene (lower). The layers are characterized by distinctly chaotic variability in textural pattern (mottled appearance, multidirectional banding), colorimetric and geochemical parameters (sawtooth-like distribution curves). Such character of changes is associated with the physical action of dragging keels of ice/icebergs exerted on the seafloor and is referred to as ice gauging (scouring). Its analysis can be used for identification of ice scour-affected layers in other sediment cores collected in this region, and for the purpose of creating a representative database, predicting their occurrence and developing adequate measures to minimize the damaging impact from drifting sea ice and icebergs on the seafloor within the bounds of the Arctic shelf.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"43264293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnetovariational Sounding in South Vietnam according to the Dalat Observatory Data","authors":"S. Starzhinskii","doi":"10.2113/rgg20224481","DOIUrl":"https://doi.org/10.2113/rgg20224481","url":null,"abstract":"\u0000 ––This paper describes a three-dimensional inversion of magnetovariational tippers calculated for the Dalat observatory in South Vietnam on the basis of the geomagnetic variation records obtained from the INTERMAGNET network. The frequency dependences of the tippers are inverted using the ModEM software, which makes it possible to construct a geoelectric model of the Dalat zone in a 300 × 300 × 150-km spatial region (x, y, and z axes, respectively) with its center located at the observatory. The resulting model of the geoelectric section contains both surface and deep conductive blocks located at the top and bottom of the Earth’s crust and in the upper mantle. The central part of the upper local conducting block with a resistivity of 0.5–1.0 Ohm⋅m is located near the observatory at a depth of 12–14 km. A more massive conductive block is located to the east of the observatory in the coastal region. Its central part with a resistivity of 0.3 Ohm⋅m is located at a depth of 24–28 km and extends under the continent along the coast for about 80 km. The roots of this block are visible to depths of ~100 km in the South China Sea shelf region. It is assumed that the high electrical conductivity of these blocks is provided by melting in the presence of aqueous fluids and granite series rocks, which are widely distributed in the Dalat zone. The crystallization depths of the samples of these granites estimated from the geothermobarometry data are close to the depth intervals of conductive blocks in the model section, which was also observed in the interpretation of magnetotelluric soundings in Southern Tibet, where granitoid rocks are widespread.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48656535","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Composition of the Fluid in Carbonate- and Chlorine-Bearing Pelite near the Second Critical Point: Results of Diamond Trap Experiments","authors":"A. Sokol, O.A. Koz’menko, A. Kruk, S. F. Nechepurenko","doi":"10.2113/rgg20234555","DOIUrl":"https://doi.org/10.2113/rgg20234555","url":null,"abstract":"\u0000 ––The composition of the fluid in carbonate- and chlorine-bearing pelite was experimentally studied at 3.0 GPa and 750 and 900 ºC, using the diamond trap method. The results of inductively coupled plasma atomic-emission spectrometry (ICP AES) and mass balance calculations showed that a supercritical fluid formed in the studied system at 3.0 GPa and 750 °C. The fluid is Si- and Al-rich and contains 30–50 wt.% H2O + CO2 and up to 1 wt.% Cl. The contents of other major elements decrease in the order: K > Na > Сa ≈ Fe > Mg > Mn > Ti ≈ P. Compared with supercritical fluids appeared in the systems pelite–H2O and eclogite–H2O, the fluid with high CO2 and Cl contents is richer in Fe, Ca, Mg, and Mn but poorer in Si. Silicate melt generated in this system at 900 ºС has a composition typical of pelitic melt. Our experiments reveal a set of fingerprints of element fractionation between a supercritical fluid and solids forming an eclogite-like association, namely, high mobility of P, Sr, and B and low mobility of Li and S. Thus, a supercritical fluid compositionally similar to the pelitic melts generated in subduction zones can transfer significant amounts of both volatiles (H2O, CO2, Cl, and P) and major components to the regions of arc magma generation. It is important that supercritical fluids should have trace element signatures of diluted low-temperature fluids.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"49237051","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrology of the Kureika Graphite Deposit in the Roof of the First-Rapid Trap Intrusion (Siberian Platform)","authors":"V. V. Ryabov, V. Ponomarchuk","doi":"10.2113/rgg20234492","DOIUrl":"https://doi.org/10.2113/rgg20234492","url":null,"abstract":"\u0000 ––The leading role of lithostratigraphic, structural/tectonic, magmatic, metamorphic, and fluid geologic factors in the formation of a graphite deposit is substantiated. We present the petrographic and chemical compositions of rocks and minerals of igneous rocks, the δ13С values of graphites and calcitites, the δ18O values of carbonates, the δ34S values of sulfides, and the 87Sr/86Sr and 87Rb/86Sr ratios in calcitites and microdolerite injections. The thermal effect of magmatic melt on coal led to its degassing and graphitization. The steaming of microdolerite injections with hydrocarbon fluids was probably accompanied by the removal of iron from them and the crystallization of low-Fe clinopyroxene, and the interaction of fluids with basaltic melt in the upper endocontact zone of the intrusion led to the segregation of the melt and the formation of a globular structure of rocks. The presence of a calcitite lens and a sulfide vein between the roof of the intrusion and the graphite bed is due to the earlier intrusion of sulfate salt melt and its subsequent interaction with hydrocarbon fluids, which resulted in sulfate reduction and the formation of calcitites. The sulfate reduction terminated with iron sulfurization in the basaltic melt and the formation of a sulfide vein. Sulfate salt melt was a source of heavy sulfur isotope (δ34S = 14.9–17.5‰) for sulfides and of calcium for calcitites. The similar isotope compositions of calcitites (δ13СPDB = –22.5 to –23.5‰), coals (–22.6 to –25.5‰, n = 25), and graphites (–23.5 to –25.0) suggest that coal is a source of carbon for calcitites. In the isotopic compositions of strontium (87Sr/86Sr ≈ 0.70834–0.70885) and oxygen δ18O ≈ 15‰) the calcitites are similar to the Devonian evaporites of the Siberian Platform. The isotope data (δ34S, δ18O, δ13С, and 87Rb/86Sr) point to the participation of the coal seam and anhydrite as sources of substance in the formation of calcitite and sulfide mineralization.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":null,"pages":null},"PeriodicalIF":1.1,"publicationDate":"2023-04-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46065957","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}