LITHOSPHERE (Russia)Pub Date : 2024-05-03DOI: 10.24930/1681-9004-2024-24-2-264-283
S. M. Aksenov, E. S. Zarubina, R. Rastsvetaeva, N. V. Chukanov, M. I. Filina
{"title":"Refinement of the crystal structure of christofschäferite-(Ce) and the modular aspect of the chevkinite polysomatic series with the general formula of {A4B(T2O7)2}{C2D2O8}m (m = 1, 2)","authors":"S. M. Aksenov, E. S. Zarubina, R. Rastsvetaeva, N. V. Chukanov, M. I. Filina","doi":"10.24930/1681-9004-2024-24-2-264-283","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-2-264-283","url":null,"abstract":"Research subject. The crystal structure of christofschäferite-(Ce) was previously refined in terms of the P21/m low-symmetrical space group, which allowed the local features of cationic arrangements to be determined. In this work, we set out to refine the crystal structure of christofschäferite-(Ce) in terms of the P21/a high-symmetrical space group based on the previously collected diffraction data. A topology-symmetrical analysis of the members of the chevkinite group with the general formula of A4BC2D2(Si2O7)2O8 was conducted. Materials and methods. A magmatic rock sample with christofschäferite-(Ce) inclusions was found in the vicinity of the Laacher See volcano, near Mendig, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. The crystal structure was studied using single-crystal X-ray analysis. Results. Despite an increase in the symmetry to the P21/a space group (in comparison with the previous data with the P21/m space group), the main patterns of cation distribution between the octahedral and tetrahedral sites are preserved. However, due to the lover number of cationic sites, this distribution becomes more disordered. Based on a crystal chemical analysis of the crystal structures of natural and synthetic members of the chevkinite group in the framework of the OD theory, it is possible to combine them into a united OD family with the same OD groupoid. Conclusions. According to the OD theory, there are two structural OD-subgroups of the chevkinite group (chevkinite and perrierite). The crystal structure and symmetry of possible MDO-polytypes are predicted.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"95 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141016257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-05-03DOI: 10.24930/1681-9004-2024-24-2-214-225
N. N. Eremin, O. A. Gurbanova, A. D. Podobrazhnykh, N. A. Ionidis, L. V. Schvanskaya, T. A. Eremina
{"title":"Major structural types in inorganic chemistry and mineralogy: New data","authors":"N. N. Eremin, O. A. Gurbanova, A. D. Podobrazhnykh, N. A. Ionidis, L. V. Schvanskaya, T. A. Eremina","doi":"10.24930/1681-9004-2024-24-2-214-225","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-2-214-225","url":null,"abstract":"Research subject. Structural types with different stoichiometric correlations between chemical elements. Aim. To analyze the prevalence of structural types with different stoichiometric correlations between chemical elements, such as simple substances with binary compounds, triple compounds with stoichiometry ABX3, triple compounds with stoichiometry AB2X4. Key points. The analysis was conducted using the databases of inorganic compounds ICSD (Inorganic Crystal Structure Database) and PCD (Pearson’s Crystal Data). The number of entries with the most typical structural types for 2013 and 2023 are determined. Their classifications in various databases for different years are given. The ranks of structural types for minerals and inorganic compounds are analyzed. The minerals crystallized in all the considered structural types are indicated according to the 2023 ISCD data, sampling only by the number of minerals registered in IMA (International Mineralogical Association – Commission on New Minerals, Nomenclature and Classification) for March 2023. The Russian names of minerals are presented in accordance with the database WWW-MINCRIST for the minerals crystallizing in all the structural types under consideration. Conclusions. The most probable causes for the realization of each stoichiometric correlation in various structural types are determined. The prevalence of certain structural types among inorganic compounds and minerals, as well as the underlying reasons, are discussed based on the principles of crystal chemistry.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"30 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141016925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-05-03DOI: 10.24930/1681-9004-2024-24-2-240-253
D. Banaru, S. M. Aksenov
{"title":"Combinatorial and algorithmic complexity of crystal structures","authors":"D. Banaru, S. M. Aksenov","doi":"10.24930/1681-9004-2024-24-2-240-253","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-2-240-253","url":null,"abstract":"Research subject. Numeral indexes describing the complexity of the system of contacts between structural units in crystal structures. Aim. Development of a complexity index for the system of contacts between periodic structural units based on the indices available for those between structural units in island (molecular) structures. Materials and methods. Structural data were selected from the COD, AMCSD, and CSD crystallographic databases. The system of contacts in the structures was analyzed by the Voronoi–Dirichlet polyhedra (VDP) method in the ToposPro software package. Results. The method of topological analysis of the system of contacts in molecular crystals was adapted to all heterodesmic crystal structures and tested on the structures of compounds of several classes. Target complexity indices were developed. Conclusions. Networks of contacts between periodic structural units are low-dimensional. A generalized structural class for such networks can be derived from the original crystal structure data. The algorithmic complexity of heterodesmic structures is subadditive, in contrast to superadditive combinatorial complexity. For the first time, the number of bearing contacts was calculated between periodic structural units, reflecting the algorithmic complexity of the structure at the appropriate level of structural description.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"117 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-05-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141015599","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-63-80
D. A. Staroselets, P. V. Smirnov
{"title":"Yanovstan formation of Western Siberia: Lithology, structure, and correlation of deposits","authors":"D. A. Staroselets, P. V. Smirnov","doi":"10.24930/1681-9004-2024-24-1-63-80","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-63-80","url":null,"abstract":"Research subject. Yanovstan f ormation ( J3-K1jnv) of Kimmeridgian-Early Beriasian age. Aim. To identify structural features of the Yanovstan formation, to carry out a detailed correlation of its deposits, including the development of criteria for determining the boundaries of the suite. Materials and methods. The studies were carried out on the basis of borehole data, including core material from 5 boreholes and borehole logging data from 209 boreholes. The borehole logging complex comprised the following methods: gamma ray logging, neutron gamma ray logging, acoustic logging, caliper logging, as well as apparent resistivity and self-polarization logging. The borehole sections were correlated by tracing individual sections of the geological section, which are characterized by relatively stable geophysical parameters. Additionally, a sequence stratigraphic approach was used. Results. The boundaries between the Sigov and Yanovstan formations were identified based on the description of core material and its comparison with the borehole logging data. The Yanovstan formation was subdivided into three units proposed by the authors: lower (ЯНв), middle (ЯНб), and upper (ЯНa). A borehole correlation of the units of the formation was carried out, on the basis of which maps of the total thickness and net-to-gross ratio and the structural plan of each of the identified stratigraphic units were constructed. It was determined that the total thickness of the lower unit reaches 80 m and is characterized by maxima within the eastern part of the study area. The thickness of the upper unit reaches 240 m and is identified within the northeastern part of the area. This part is represented by a predominantly clay composition. The total thickness of the formation as a whole varies from 40 m in the west to 320 m in the northeast. The thicknesses of the middle unit are relatively consistent throughout the study area. The sandiness of the lower unit varies from 0 to 0.27 units; the upper ranges within 0–0.45 units. The middle unit is not characterized by the presence of sandstones. Conclusions. The theory about the supply of sedimentary material during the sedimentation of the suite from paleomounts within the eastern edge of the West Siberian Jurassic paleobasin was confirmed. An assumption was made that the increased thickness of the predominantly clayey suite within the northeastern part of the study area is associated with the redistribution and transfer of terrigenous material carried from the Siberian land by currents moving unidirectionally along the coast (counterclockwise). These currents thus seized the lightest (clayey) material and transported it to the northern part of the basin.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"70 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140261270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-173-194
A. R. Yusupova, N. G. Nurgalieva, D. M. Kuzina, A. M. Rogov, G. R. Nigamatzyanova
{"title":"Lithological features of Lake Bannoe sediments (Southern Urals) as an indicator of environmental and climate changes in the Holocene","authors":"A. R. Yusupova, N. G. Nurgalieva, D. M. Kuzina, A. M. Rogov, G. R. Nigamatzyanova","doi":"10.24930/1681-9004-2024-24-1-173-194","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-173-194","url":null,"abstract":"Research subject. Bottom sediments of Lake Bannoe (Southern Urals). Aim. Identification of lithologic features of Lake Bannoe sediments, which could reflect sedimentation conditions in the Holocene. Materials and methods. The detailed complex analysis included radiocarbon dating, grain-size analysis, X-ray diffraction analysis, electron microscopy, X-ray fluorescence and isotope analysis, coercive spectrometry and pollen analysis. Results. Radiocarbon dating showed that sedimentation in Lake Bannoe began no later than ~13 thousand years ago. Combination of data from various laboratory studies unraveled four lithological zones and the corresponding stages in the sedimentation history. The grain size, allothigenic particles, carbonate minerals, organic matter and isotopic composition of carbon and oxygen are the most informative indicators. Grain size variations and the ratio between allothigenic and carbonate components reflect changes in the Lake’s depth and clastic material supply, which, in turn, is associated with humidity. Organic matter parameters (TOC, δ13Corg, C/N ratio) can be considered as indicators of climate-sensitive changes in bioproductivity of the sedimentation basin. They also reflect the ratio of exogenous and endogenous organic matter in the sedimentary environment. The isotopic composition of carbon and oxygen (δ13Ccarb, δ18Ocarb) in sedimentary carbonates is an informative indicator of lithological zones and climatic events of the Holocene due to its sensitivity to changes in biomass, temperature fluctuations, and fresh water inflow. The paramagnetic component k_para was used as an indicator of the allothigenic material input into the lake basin for the first time in this region. Conclusions. The granulometric, mineral, and chemical composition, as well as the magnetic properties of Lake Bannoe sediments reflect the history of Lake sedimentation in the Southern Urals, which agrees mainly with the climate stages of the Holocene.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"139 26","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140078177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-115-129
A. F. Georgievskiy, V. Bugina
{"title":"Gold in phosphorites: Accumulation forms and practical significance","authors":"A. F. Georgievskiy, V. Bugina","doi":"10.24930/1681-9004-2024-24-1-115-129","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-115-129","url":null,"abstract":"Research subject. The gold-bearing potential of modern (oceanic) and ancient industrial types of phosphorite ores, including aphanitic, microgranular, granular, nodular, shell and karst. Aim. To assess the ability of phosphorites to accumulate gold to industrial concentrations. This issue has been actively discussed in the geological community in recent years due to the advent of high-precision methods for studying matter. Methods. Russian and foreign publications, unpublished geological data, as well as the authors’ data collected over a 30-year period of studying phosphorites. Results and discussion. In the section, 14 packs of rocks were identified, which are represented by 6 lithological types of secondary dolomites. Their distribution along the section, along with the presence of characteristic faunal remains, made it possible to establish three members in the section, which can be correlated with the Katian, Hirnantian, and Ruddanian stages of the General Stratigraphic Scale. Conclusion. Conditions for the possible joint accumulation of phosphates and gold are manifested in black shale basins, as well as in shelf shallow waters with glauconite-sand sediments. However, due to significant differences in the natural features of gold and phosphates, their industrial clusters are formed separately from each other. This is evidenced by the insignificant accumulation of phosphorus in the ores of gold deposits of black shale formations,as well as its low-quality concentrations in industrial phosphorite beds of phosphorite-bearing basins. For gold, phosphorites are only temporary collectors, the productivity of which depends on the combination of many, frequently random and slightly related factors.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"35 15","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140262776","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-147-172
Ya. A. Rybnikova, T. V. Rundkvist
{"title":"Low-sulfide platinum–metal deposits in the Kola region: A comparative analysis of the Yuzhnosopchinskoye ore occurrence and the Fedorova Tundra deposit","authors":"Ya. A. Rybnikova, T. V. Rundkvist","doi":"10.24930/1681-9004-2024-24-1-147-172","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-147-172","url":null,"abstract":"Research subject. Platinum–metal objects of the Kola region (contact type mineralization), including the Yuzhnosopchinskoye ore occurrence within the same-name massif belonging to the Early Proterozoic Monchetundra intrusion and the Fedorova Tundra deposit located in the western part of the Early Proterozoic Fedorovo-Pansky layered complex. Aim. To establish the formation conditions of platinum-metal ores in the Yuzhnosopchinskoye ore occurrence and the Fedorova Tundra deposit. Methods. Comparison of the geological structure and petro-geochemical features of rocks and ores from the two objects using statistical analysis. Results. Both the Yuzhnosopchinskoye ore occurrence and the Fedorova Tundra deposit belong to the contact type of platinum group element deposits. The main characteristic feature is confinement of the ore zone to the contact of two magmatic phases. In the contact zone, igneous breccia, pegmatoid, and vein bodies are widespread, with the latter being especially common in the Yuzhnosopchinskoye ore occurrence. In Yuzhnosopchinskoye ore occurrence, breccia fragments are represented by orthopyroxenites and melanocratic norites of the early magmatic phase (layered series of rocks). They were cemented by barren gabbroids of the later magmatic phase. In the Fedorova Tundra deposit, breccia zone fragments are also composed of orthopyroxenites and melanocratic norites of the early magmatic phase (layered series of rocks). They were cemented by taxitic ore-bearing gabbronorites of the late magmatic phase. Rocks of the two objects with a similar nomenclature demonstrate slight systematic differences in the composition of petrogenic components, as well as in REE and rare elements. Taxitic gabbronorites (rocks of the marginal series) from the Fedorova Tundra deposit have no rock analogues in Yuzhnosopchinskoye ore occurrence. A comparison of similar amounts of two data sets (more than 2000 samples each) of Pt, Pd, Au, Ni, and Cu sampling showed that the content of all precious metals in the Fedorova Tundra deposit was consistently higher than that in the Yuzhnosopchinskoye ore occurrence. The Fedorova Tundra deposit is homogeneous, with an average Pd/Pt ratio of 4.5. The Yuzhnosopchinskoye ore occurrence is heterogeneous and, on average, slightly more ‘platinum’ and less ‘palladium’ than the Fedorova Tundra deposit. Conclusions. The two ore objects of the contact type are similar in many respects, mainly differing in the conditions of mineralization formation. The Yuzhnosopchinskoye ore occurrence entered the contact zone from the rocks of the layered series due to the activation of the ore matter during intrusion of the late gabbroid intrusive phase. The Fedorova Tundra deposit entered the contact zone together with the late ore-bearing gabbronorite magmatic phase.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"73 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140261264","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-130-146
L. Rakov, V. Prokofiev, V. A. Kovalenker, L. D. Zorina
{"title":"Lattice defects in the disordered quartz structure of gold deposits of the Darasun ore field (Eastern Transbaikalia)","authors":"L. Rakov, V. Prokofiev, V. A. Kovalenker, L. D. Zorina","doi":"10.24930/1681-9004-2024-24-1-130-146","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-130-146","url":null,"abstract":"Research subject. The composition, properties, and connection of the lattice defects in the disordered s tructure of quartz with the conditions of its formation. Materials and methods. The quartz of the gold deposits of the Darasun ore field – Darasun, Teremkinskoye, and Talatuy – were studied. For the purpose of comparative analysis, gold-ore quartz from the deposits of Northern Kazakhstan was used. Registration of centers in quartz samples was carried out by the EPR method. When interpreting the obtained results, genetic information consisting in the distribution of substitutional Ge and Ti impurities in quartz was used. Results. Two groups of paramagnetic centers were identified in the quartz under study. One of them is associated with substitutional Al, Ti, and Ge impurities in quartz zones with an ordered crystal structure, while the other is associated with the lattice defects localized in the disordered crystal structure of quartz. The latter group includes several types of E'-centers formed in quartz glass and Al-X-centers caused by Al3+ ions associated with oxygen vacancies. In the case of stable thermodynamic conditions of mineral formation, a linear relationship was established between the concentrations of Al-X-centers (CAl-X) and E'-centers (CEs). Under a change in thermodynamic conditions, a deviation of the points from the CEs(CAl-X) dependence was observed. Conclusions. The type of CEs(CAl-X) dependence is determined by the thermodynamic conditions of mineral formation and can be used to identify cases of non-equilibrium solidification of quartz.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"10 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140261889","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-98-114
L. A. Shmeleva
{"title":"Upper Ordovician–Lower Silurian deposits in the Zakola section (Ilych River, Northern Urals): Composition, structure, formation environments","authors":"L. A. Shmeleva","doi":"10.24930/1681-9004-2024-24-1-98-114","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-98-114","url":null,"abstract":"Research subject. Section of boundary deposits, exposed in the right side of the Zakola stream (the right tributary of the Ilych River, Northern Urals) with a total thickness of 98 m, presented with rock samples (more than 100 pieces), thin sections (100 pieces), slabs (10 pieces), and chemical analyses (15 pieces). Aim. Detailed description of the most complete section of the Upper Ordovician–Lower Silurian boundary sediments of the Shantym facies complex with a stratigraphic reference of layers, lithological typification of sediments, and restoration of sedimentation conditions. Methods. Conventional lithological and paleontological methods were used to dissect the section. Sampling was carried out after 1 m; however, samples were additionally taken when detailed observations were possible to identify lithological and facial differences. The thin sections were studied by the classic method of optical microscopy. The study of the fauna complex was carried out both by collecting samples of the author’s rocks and by the materials of A.I. Antoshkina. In addition, stock materials were attracted. Results. In the section, 14 packs of rocks were identified, which are represented by 6 lithological types of secondary dolomites. Their distribution along the section, along with the presence of characteristic faunal remains, made it possible to establish three members in the section, which can be correlated with the Katian, Hirnantian, and Ruddanian stages of the General Stratigraphic Scale. Conclusion. The Katian deposits are represented by the Yaptikshor Formation (Strata 1), which was formed under the conditions of the lower sublittoral of a ramp-type carbonate platform with a transgressive carbonate tract and a diverse fauna. The beginning of the Hirnantian (Strata 2) is characterized by shallow water conditions of the upper sublittoral up to the littoral, which reflects a sharp shallowing at the Katian–Hirnantian boundary and corresponds to the beginning of the global early Hirnantian regression. The rocks exposed higher up the section indicate sedimentation with a certain rise in the sea level; however, the correlation of this part of the section with the upper part of the Verkh Ruchey Formation is complicated by the fragmentary nature of the outcrops. The overlying Ruddanian deposits (Strata 3) were accumulated on the outskirts of a ramp-type carbonate platform under the conditions of the lower sublittoral, which corresponds to the beginning of the Early Silurian global transgression.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"42 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140078037","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
LITHOSPHERE (Russia)Pub Date : 2024-03-06DOI: 10.24930/1681-9004-2024-24-1-81-97
T. Beznosova, V. A. Matveev
{"title":"Stratotypic section of the Wenlockian Voyvyv horizon (Western slope of the Subpolar Urals)","authors":"T. Beznosova, V. A. Matveev","doi":"10.24930/1681-9004-2024-24-1-81-97","DOIUrl":"https://doi.org/10.24930/1681-9004-2024-24-1-81-97","url":null,"abstract":"Research subject. The paper presents the results of a study into the carbonate-terrigenous section of 197.8 m-thick Wenlockian section in the Shchugor River basin, which is proposed as the stratotype of the regional horizon. Materials and methods. The study was based on numerous samples from Lower Silurian deposits collected by the authors in different years during fieldwork on the Western slope of the Circumpolar Urals and the Chernov and Chernyshev uplifts, as well as the biostratigraphic, paleontological, lithological, and C-isotopic data obtained during these works. Results. The obtained data allowed revising some of the established ideas about the structure of the Lower Silurian section and the position of the boundary level between the Llandoverian and Wenlockian in the Subpolar Urals and to identify a new regional subdivision with the name “Voyvyv”. The traced formation conditions of shallow carbonate sediments of the Voyvyv horizon and the consistent change of zonal taxa of marine fauna in the stratotype section indicate similarity with coeval strata on the Chernov and Chernyshev uplifts and Dolgy Island. Conclusions. The results of the study of Wenlockian Voyvyv deposits in the Timan-North Urals region showed that the section in the Shchugor River basin in outcrop 10c can be considered the most informative in the Northern Urals region in terms of exposure degree, established stratigraphic completeness, and preservation of macro- and microfauna.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"52 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140260778","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}