Doklady Earth Sciences最新文献

{"title":"Seismotectonic Model of the Focal Zone of the November 25, 2016, Aketao Earthquake MW 6.6 (China)","authors":"V. N. Morozov, A. I. Manevich","doi":"10.1134/s1028334x24603675","DOIUrl":"https://doi.org/10.1134/s1028334x24603675","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The results of modeling the stress–strain state of the epicentral zone of the strong crustal earthquake Aketao, which occurred near Muji (China) on November 25, 2016, with magnitude <i>M</i>_<i>w</i> 6.6, are presented. The finite element method is used to model the stress–strain state in the epicentral zone with subsequent construction of stress intensity maps before and after the earthquake. The possibility to determine the location of the rupture origin and its extent, including estimation of the scalar seismic moment and the earthquake magnitude, is shown. The possibility to calculate the seismic moment rate as a function of time <i>M</i>_<i>o</i>(<i>t</i>) based on the model of the stress–strain state of rupture (earthquake focus) is presented for the first time, which allows obtaining synthetic seismograms and accelerograms of a potential earthquake in the future.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"40 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252180","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":"Crystal Structure and Raman Spectroscopy of Synthetic Potassium Richterite","authors":"E. V. Limanov, V. G. Butvina, O. G. Safonov, A. V. Spivak, A. V. Kuzmin, L. Ya. Aranovich","doi":"10.1134/s1028334x24602906","DOIUrl":"https://doi.org/10.1134/s1028334x24602906","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The structures of two K-richterite crystals with the crystal chemical formulas (K_0.44Na_0.32<span>(square )</span>_0.24)_Σ=1(Ca_1.18Na_0.82)_Σ=2Mg₅Si₈O₂₂OH₂ and (K_0.83Na_0.02<span>(square )</span>_0.15)_Σ=1(Ca_1.11Na_0.89)_Σ=2Mg₅Si₈O₂₂OH₂ synthesized at a pressure of 3 GPa and a temperature of 1000°С in the MgSiO₃ + CaMgSi₂O₆ + K₂CO₃ + Na₂CO₃ + CO₂ + H₂O system were studied by single-crystal X-ray analysis and Raman spectroscopy. The monoclinic cell parameters were obtained: <i>a</i> = 10.0256(5) and 9.9748(11) Å, <i>b</i> = 17.9874(7) and 17.9879(16) Å, <i>c</i> = 5.2687(3) and 5.2746(6) Å, <i>V</i>_e.c. = 916.17(18) and 918.52(8) ų, β = 104.520(12)° and 104.821(5)°, sp. gr. <i>С</i>2/<i>m</i> (12), and <i>Z</i> = 2. The sites <i>M</i>(1), <i>M</i>(2), and <i>M</i>(3) are inhabited by Mg²⁺, while site <i>M</i>(4) is occupied simultaneously by Ca²⁺ and Na⁺. The Na⁺ cations not included in <i>M</i>(4) are located in position <i>A</i>, which also accommodates K⁺ cations. Raman spectroscopy made it possible to reveal vacancies in position <i>A</i> in both samples. The structure corresponds to the “ideal” structure of richterite group minerals. The unit cell volume of the measured crystals is directly proportional to the K content in position <i>A</i>. Based on the generalization of new and published data, an equation of the dependence of <i>V</i>_u.c. for amphiboles of the richterite Na(NaCa)Mg₅Si₈O₂₂(OH)₂–K-richterite K(NaCa)Mg₅Si₈O₂₂(OH)₂ series with a low tremolite component on the K content in position <i>A</i> is proposed.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"25 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252179","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":"Radionuclides (40K, 232Th, 226Ra, 137Cs, and 90Sr) in Agroecosystems of the Central Chernozem Region","authors":"S. V. Lukin","doi":"10.1134/s1028334x24603134","DOIUrl":"https://doi.org/10.1134/s1028334x24603134","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Studies were conducted in 2023–2024 at reference sites of Belgorod oblast. The study procedure is conventional in the agrochemical service. The purpose of this work is to study the specific activity of natural and artificial radionuclides in the soils and the plants of certain agroecosystems. These studies have shown that the average specific activity of ⁴⁰K does not vary significantly in the leached (539 Bq/kg), typical (544 Bq/kg), and ordinary (573 Bq/kg) arable chernozems, while in the residual carbonate chernozems, this parameter (207 Bq/kg) is 2.60–2.77 times lower. The average specific activity of ²³²Th in the leached (39.2 Bq/kg), typical (42.9 Bq/kg), and ordinary (46.7 Bq/kg) chernozems is 1.97–2.35 times higher than in the residual carbonate (19.9 Bq/kg) chernozems. The average specific activity of ²²⁶Ra in the soils studied do not differ significantly, staying within 17.3–18.9 Bq/kg. In the soils of the western and eastern areas of the region, the specific activity of ¹³⁷Cs ranges within 5.9–19.6 and 16.3–87.2 Bq/kg, respectively. The specific activity of ⁹⁰Sr in the soils of the western regions is below 3, whereas for the eastern, it is below 5 Bq/kg. In the plant products studied, the average specific activity of ⁴⁰K varies within 111–597 Bq/kg, while those of ²³²Th and ²²⁶Ra do not exceed 6 and 8 Bq/kg, respectively. The specific activity of ¹³⁷Cs is less than 3, and that of ⁹⁰Sr is 2 Bq/kg, which is significantly lower than the established maximum levels for this parameter.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"39 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252205","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 Relationships and Distribution of S, Fe, Co, Ni, Re, Os, and Pt between Metal and Sulfide Melts in the Basalt–Fe–FeS–C System at 1400°C and 4 GPa","authors":"N. S. Gorbachev, Yu. B. Shapovalov, A. V. Kostyuk, P. N. Gorbachev, A. N. Nekrasov","doi":"10.1134/s1028334x24603092","DOIUrl":"https://doi.org/10.1134/s1028334x24603092","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The immiscibility of a Fe–FeS–C melt into Fe-metal (Mc) and Fe-sulfide (Ms) liquids has been studied in the basalt–Fe–FeS–C system at 4 GPa and 1400°C. The partition (D) and distribution (Kd) coefficients of S, Fe, Co, Ni, Re, Os, and Pt between the Mc and Ms melts are determined. The partition coefficients D served as indicators of the siderophilic and chalcophilic properties of each element, and Kd characterized their interelemental ratios during fractionation. In the Fe–Os–Co–Re series with D &gt; 1, siderophilic properties prevail, which increase with increasing values of the partition coefficients: 1.2–1.5–1.6–12.6. In the Ni–Pt–S series with D &lt; 1, chalcophilic properties prevail, which increase with decreasing D: 0.9–0.6–0.1. The values of the distribution coefficients Kd Re/Os (8.4) and Pt/Os (0.4) indicate the fractionation of Re and Pt relative to Os, with enrichment of rhenium in a metallic melt and platinum in a sulfide melt and a shift in the fractionation of the Re/Os and Pt/Os relations and related systems of ¹⁸⁷Re/¹⁸⁷Os and ¹⁹⁰Pt/¹⁸⁶Os isotopes. The genetic relationship of magmatic sulfide mineralization in intrusive of the Upper Norilsk (ore-bearing) and Lower Norilsk (ore-free) types with metal–sulfide immiscibility of sulfide magma is evidenced by the similarity of the Re/Os ratio in the Upper Norilsk intrusive with the ratio in the Ms component, and in the Lower Norilsk intrusive with the Mc component.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"54 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252176","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":"Age and Composition of the Middle–Upper Jurassic Sediments in the Central Zone of the Polousnyi Terrane (Northern Yakutia)","authors":"E. V. Vatrushkina, M. V. Gertseva, V. V. Kostyleva, S. D. Sokolov","doi":"10.1134/s1028334x24603353","DOIUrl":"https://doi.org/10.1134/s1028334x24603353","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>New data on the composition and structure of the Jurassic section in the Central zone of the Polousnyi Terrane are presented. The arkosic composition of sandstones and the predominance of granites in the sediment provenance was established by petrographic data. Both redeposited fragments of volcanic rocks of various composition and synchronous pyroclastic material were identified in the sandstones. U–Pb isotope dating of detrital zircons and the obtained maximum depositional age made it possible to revise the stratigraphic volume of the Jurassic sediments exposed in the Central Zone and to limit it from the Upper Bajocian to the Tithonian. The immaturity of the composition and the absence of reliably dated Hettangian–Aalenian sediments indicate a new cycle of sedimentation and contradict the existence of a single Verkhoyansk passive margin in the Triassic–Jurassic.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"14 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252181","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":"Analysis of Views about Increasing the Water Stability of Soils","authors":"G. N. Fedotov, S. A. Shoba, I. V. Gorepekin, D. A. Tarasenko","doi":"10.1134/s1028334x24603584","DOIUrl":"https://doi.org/10.1134/s1028334x24603584","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>One of the methods to increase the water stability and erosion resistance of soils is the use of structure-forming polymers. It is believed that the mechanism of their action is based on strengthening the bonds between particles of clay minerals. This approach ignores the existence of organomineral gels on the surface of mineral particles, which can affect the effectiveness of polymers. The purpose of this work is to investigate the interaction of a number of structure-formers used to increase water stability and erosion resistance with soil components. In model experiments on the interaction of polymers with soil components, suspensions of humate and bentonite are used. The results are verified on leached chernozem. The effectiveness of polymers is evaluated by the blade method used to determine the water stability of soils, and the interaction of particles in suspensions in model experiments is evaluated by laser diffractometry. It is established that, in solutions of humates with polymers, the size of particles formed in solutions increases with increasing hydrophobicity of the polymers. No such unambiguous relationship is found in bentonite suspensions with polymers. Verification of the results of model experiments on chernozem has shown that the water stability of the aggregates increases with an increase in the hydrophobicity of the polymer used for treatment. To further verify the role of organic matter in ensuring soil water stability, the possibility of using oppositely charged humic substances and iron sol to increase soil water stability is evaluated. The experiments have shown that the use of iron sol increases the water stability of chernozem. Moreover, at an increase in the pH of the iron sol solution from 1.7 to 6.1, the effect value increases from 11 to 59%. The results of this study suggest that shifting focus from strengthening the adhesion between mineral particles to strengthening organic and organomineral interactions should be considered as a reserve for increasing the effectiveness of compositions to maintain the soil structure.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"54 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252182","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":"The Middle to Late Quaternary Stratigraphy and Sedimentation Paleoenvironment in the Norwegian Sea Based on Complex of Paleoproxies","authors":"E. A. Novichkova, L. L. Demina, D. P. Starodymova, A. G. Matul, M. D. Kravchishina, M. P. Chekhovskaia, N. S. Oskina, L. A. Lozinskaia, S. V. Slomnyuk, A. S. Solomatina, K. S. Iakimova","doi":"10.1134/s1028334x24602876","DOIUrl":"https://doi.org/10.1134/s1028334x24602876","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>A complex of sedimentological, geochemical, and micropaleontological methods was used to study and compare five new sediment cores along a submeridional transect from the middle to the north of the Norwegian Sea. A combined analysis of the distribution of ice-rafted debris, polar/subpolar foraminifera, calcium carbonate, organic carbon, and continuous geochemical scanning records revealed an alternation of Middle–Late Quaternary glacial and interglacial intervals over the last 260 000 years. In the Late Middle Pleistocene glaciation (MIS 6, 8), the supply of terrigenous material had a much greater influence on regional sedimentation than in the Late Pleistocene (MIS 2–4). Local (between the central and northern parts of the Norwegian Sea) differences in glacial and interglacial sedimentation are shown.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"39 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252178","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":"Gold Mineralzation from Calcite-Dolomite Carbonatite of the Guli Massif (Maimecha-Kotui Province, Polar Siberia): First Results","authors":"K. N. Malitch, G. V. Lipenkov, D. A. Ozornin, M. V. Naumov, I. Yu. Badanina, V. A. Bulatov, A. A. Voitin","doi":"10.1134/s1028334x24603079","DOIUrl":"https://doi.org/10.1134/s1028334x24603079","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Complex gold-iridium-osmium placer deposits associated with the Guli massif of ultramafic, alkaline rocks and carbonatites are located within the Maimecha-Kotui province in the northern part of the Siberian Platform. Unlike natural Os-Ir alloys, which are genetically related to ultramafic rocks, the bedrock source of gold remains controversial. We report, for the first time, morphological and compositional features of gold mineralization from calcite-dolomite carbonatite of the Guli massif. Gold minerals are represented by natural Au-Ag alloys containing gold (69.64–88.57 wt %) and silver (11.73–30.83 wt %) with low concentrations of copper (up to 0.18 wt %), which predominate over minerals of the system Au–Cu–Ag (e.g., natural alloys Au_0.74Cu_0.14Ag_0.12 and Ag_0.51Au_0.47Cu_0.02, tetra-auricupride (AuCu) and auricupride (Cu₃Au)). Gold minerals are characterized by an early pentlandite-troilite-chalcopyrite association that form polyphase euhedral inclusions. Later galena (PbS) occurring in the form of subhedral monophase inclusions is replaced by cerussite (PbCO₃). The revealed similarity of gold minerals and mineral assemblages in gold from calcite-dolomite carbonatite with those of gold minerals from placer deposits of the Guli massif indicates that derivatives of ijolite-carbonatite magmatism played a significant role in gold ore formation.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"30 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252208","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":"Long-Term Changes in the Activity of Wave Disturbances in the Mesopause Region","authors":"V. I. Perminov, N. N. Pertsev, V. A. Semenov, P. A. Dalin, V. A. Sukhodoev","doi":"10.1134/s1028334x24603511","DOIUrl":"https://doi.org/10.1134/s1028334x24603511","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Long-term trends and dependences on solar activity were derived for wave disturbances at mesopause altitudes (80−100 km) based on temperature variations obtained by spectral observations of the hydroxyl airglow at the Zvenigorod Science Station, Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, in 2000−2024, as well as by methods of statistical analysis. Their activities were determined by digital frequency filtering in three regions of wave periods, such as 0.7−2.0, 1.4−4.1, and 2.7−8.2 h with maxima at 1, 2, and 4 h. The root-mean-square values of temperature half-differences served as an indicator of wave activity. Both year-round and average seasonal (winter and summer) values were analyzed. According to the study results, the wave activity is characterized by positive trends with their dependence on the frequency band of disturbances (in winter, the trend is greater in the high-frequency band, and in summer, the trend is greater in the low-frequency band). The dependence on solar activity is positive. Its values are greater for the high-frequency band of disturbances, as well as in winter.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"39 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142252177","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":"The Natural Habitat of Mammuthus Trogontherii in the Southern Part of the Russian Far East in the Middle Pleistocene","authors":"P. S. Belyanin, N. I. Belyanina","doi":"10.1134/s1028334x24603523","DOIUrl":"https://doi.org/10.1134/s1028334x24603523","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Palynological data obtained from sediments that include the first find of a tusk fragment of the Trogontherii elephant (<i>Mammuthus trogontherii</i>) in Primorskii krai allowed us to reconstruct its living environment in the Middle Pleistocene. The reconstructed plant formations indicate warmer and drier climatic conditions during the existence of <i>Mammuthus trogontherii</i> in the southern part of the Russian Far East than the modern conditions. The ecosystems of the region had a more complex structure. Nemoral plants were more widely represented in them. Mesophilic pine–spruce forests with broadleaf trees and larch–birch sparse forests were the main feature of landscapes. Shrubby birch and alder thickets, sparse larch-birch forests, and sphagnum mires occupied plains and lakeshores.</p>","PeriodicalId":11352,"journal":{"name":"Doklady Earth Sciences","volume":"1 1","pages":""},"PeriodicalIF":0.9,"publicationDate":"2024-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142268774","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}