LITHOSPHERE (Russia)最新文献

{"title":"New Data on Carboniferous Deposits in the Southern Part of the East-Timan Megaswell","authors":"E. Ponomarenko, R. Ivanova, P. Beznosov","doi":"10.24930/1681-9004-2023-23-3-325-347","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-3-325-347","url":null,"abstract":"Research subject. Lower Pennsylvanian deposits exposed by mine excavations in the watershed part of South Timan.Materials and methods. The research material included data obtained by a field description of sections and an optical microscopy analysis of rock samples (26 specimens). For micropaleontological analysis, oriented thin-sections (97 specimens) were additionally prepared. Trace fossil taxa were determined based on both field photographs and collected specimens. Four oriented rock samples were used to determine the phase composition of the clay fractions from diffraction patterns.Results. The rocks of the Askynbashian (2.7 m), Tashastian (1.4 m), and Akavasian (2.5 m) Regional Stages of the Bashkirian Stage are exposed in the Ikhnitovyi quarry, and the Upper Vereiskian deposits of the Moscovian Stage (1.9 m) are exposed in the Vyemka section. The Ikhnitovyi quarry section exhibits a distinctly cyclic pattern. The cycle bases are distinguished by the appearance of coral and algae limestones, above which thin bedded fine-grained bioclastic and peloidal limestones occur. Greenish illite and chlorite clays indicate shallow sedimentation environments. The carbonate sediments experienced two cementation stages separated by the phase of compaction. The trace fossil assemblage recognized in the Ikhnitovyi quarry characterizes Cruziana ichnofacies. The Vyemka section is of particular interest due to the find of Eofusulina and the presence of typical carbonate tempestites.Conclusions. The Bashkirian deposits were accumulated under quiet shallow-water conditions (coral and algae limestones), on low-gradient tidal flats (fine-grained grainstones), and under a low hydrodynamic activity (probably low-amplitude tides). The illite and chlorite clays identify the accumulation of aeolian material (clay paticles) in ponds.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"64 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85748701","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}

{"title":"Composition and formation conditions of nephrite, Nyrdvomenshor deposit, Polar Urals","authors":"E. Kislov, M. P. Popov, F. M. Nurmukhametov, V. F. Posokhov, V. V. Vanteev","doi":"10.24930/1681-9004-2023-23-2-270-291","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-270-291","url":null,"abstract":"   Research subject. Nephrite and related rocks from the Nyrdvomenshor deposit in the Polar Urals were studied. The Nyrdvomenshor deposit is located in the exocontact of the Rai-Iz ultramafic massif, confined to the Main Ural Fault. The deposit was developed in the process of geological exploration; a license has been issued for a part of the deposit.   Aim. To study the nephrite and related rocks from alluvial of the deposit, to formulate a model of its origin.   Methods. Qualitative characteristics were assessed visually using a binocular microscope and a special flashlight. The chemical composition was determined by the X-ray fluorescence method. The contents of trace elements were determined by ICP-MS analysis. The mineral composition was studied on a scanning electron microscope with an energy dispersive microanalysis system. Measurements of the isotopic composition of oxygen were carried out.   Results. In addition to vesuvianite rodingite, hydrogarnet rodingite was found to be common at the deposit. The studied nephrite is substandard. Tremolite predominates in nephrite, diopside forms relic grains. Uvarovite is widespread, forming both idiomorphic grains, sometimes sheath, less often elongated xenomorphic, and replacing chromite. Omphacite overgrows grains of chromite and uvarovite. Grains of the Fe-dominant mineral of the shuiskite group are noted.   Conclusions. Nephrite was formed through both metamorphic and metasomatic processes. Serpentinite was replaced by diopside, which was then replaced by nephrite. Metamorphism enhanced the metasomatism of the serpentinite melange and provided the cryptocrystalline tangled fibrous structure of the nephrite. Then metamorphism and metasomatism led to the formation of omphacite and cracking of the nephrite, which reduced its quality. As these processes progressed, the contribution of the crustal fluid increased, which is confirmed by the results of studying the oxygen isotopic composition of nephrite and other rocks of the deposit.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"04 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86106623","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}

{"title":"Magnetic constraints and susceptible inversions of Balapur Fault at central Kashmir Basin, NW Himalaya","authors":"A. M. Dar, S. K. Bukhari","doi":"10.24930/1681-9004-2023-23-2-292-302","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-292-302","url":null,"abstract":"Research subject. Subsurface investigations of the Balapur Fault at central Kashmir Basin, NW Himalaya through groundmagnetic surveys and data interpretations.   Materials and methods. The total magnetic intensity data was obtained using ground magnetic surveys carried out by proton precession magnetometers at 15 m spacing. The magnetic constraints and inversions of the Balapur fault in the central Kashmir basin of NW Himalaya were analyzed.   Results. The total magnetic intensity was found averaging at 97.7 with 45.8 nT as magnetic minima and 140.9 nT as magnetic maxima. The minima’s ranging from 45.8 and 55.8 nT in the gridded profile are inferred at the Balapur fault. Further, the fault-related susceptibility index was recorded from 0.0035 SI to 0.0015 SI, and the observed and predicted response values were found ranging between 67.1 to 87.7 and 67.4 to 86.6 nT respectively.   Conclusion. The study suggests that the Balapur fault in the central Kashmir has produced high subsurface hydraulic activities and, therefore, evident low magnetic anomalies. The analysis reveals a thick minima region related to the fault and also indicated the presence of associated structures with the main Balapur fault segment.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"21 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83290770","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}

{"title":"Almandine jewelry garnet from the Kitelya deposit (Karelia): composition and spectroscopic properties","authors":"V. Lyutoev, A. Makeyev, E. N. Terekhov","doi":"10.24930/1681-9004-2023-23-2-247-269","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-247-269","url":null,"abstract":"   Research subject. The chemical composition and spectroscopic properties of almandine jewelry garnets from the Kite-lya deposit in the Northern Ladoga region (Karelia).   Materials and methods. The chemical composition, impurity elements, mineral inclusions and spectroscopic properties of almandine jewelry crystals were studied using IR and Mössbauer spectroscopy.   Results. Garnet crystals were found to exhibit a weakly pronounced zonal composition, varying from Alm75Pir15Sps7Grs3 in the center to Alm80Pir14Sps4Grs2 at their edges. Therefore, the Ca and Mn contents decrease towards the grain edges. This zonality of garnets is characteristic of the processes of progressive metamorphism of their host rocks. The garnet crystals feature small inclusions of quartz, chlorite, mica FACI (biotite), ilmenite, rutile, monazite, zircon and pyrrhotite. The composition of chlorite, biotite and zircon was established. The parameter of the cube unit cell ao = 11.522 ± 0.003 Å was calculated. The IR absorption spectra of 995, 966, 901, 878, 638, 568, 528, 476 and 455 cm–1 are characteristic of the pyrope-almandine difference. Mössbauer spectroscopy revealed an insignificant admixture of trivalent iron (Fe3+) in the structure of Kitelya garnets (≈1 % of the amount of isomorphic iron). The obtained optical absorption spectra of garnet plates in the visible light spectrum indicate that Fe2+ ions in dodecahedral positions, to a lesser extent dodecahedral Mn2+ ions, as well as possibly octahedral Fe3+ ions are responsible for the bright red-crimson color of pyrop-almandine from the Kitelya deposit.   Conclusions. A “portrait” of typomorphic features (composition and properties) of the pyrope-almandine jewelry garnet from the Kitelya deposit was obtained. This portrait can be used when analyzing the historical finds of faceted or cabochonized differences of almandine in jewelry, church utensils in both Russia and Europe (where this jewelry material was exported during the 17th century). The preservation of garnet jewelry differences in the host rock is due to the presence of thin amorphous kelefite shells or soft minerals (sericite, chlorite, kaolinite etc.).","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77189810","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}

{"title":"Trace and rare-earth elements in garnets from silicate-carbonate formations of the Kusa-Kopan complex (Southern Urals)","authors":"V. S. Stativko, S. Skublov, V. Smolenskiy, A. Kuznetsov","doi":"10.24930/1681-9004-2023-23-2-225-246","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-225-246","url":null,"abstract":"   Research subject. Garnets from silicate-carbonate formations and their halos with skarn mineral associations, developedin the historical mines and pits of the Southern Urals: Zelentsovskaya, Nikolaje-Maximilianovskaya, Akhmatovskaya,Perovskitovaya, Gubensky massif, Praskovie-Evgenyevskaya and Shishimskaya.   Aim. To study the nature of silicate-carbonate formations of debatable origin.   Materials and methods. The composition of garnets distributed both in silicate-carbonate formations and in rocks with skarn mineral associations was analyzed using SEM-EDS (IPGG RAS) and SIMS (Yaroslavl branch of IPT RAS).   Results. The garnets from silicate-carbonate rocks show predominantly a dark to black color, a combination of simple rhombododecahedron and tetragontrioctahedron shapes. In terms of composition, these materials correspond to andradite – Ti-andradite, with the share of shorlmite and morimotoite end-members reaching 30 %. The garnets from calcareous skarns are reddish in color and have a rhombododecahedric habitus. In terms of composition, these garnets correspond to an andradite-grossular isomorphic series, with the share of shorlomite and morimotite end-members not exceeding 3 %. For these garnets, the content of trace and rare-earth elements was determined for the first time, and a posi tive correlation of Ti with U, Y, Zr, Hf and Nb was established. Figurative points on binary diagrams (in coordinate axes of rare-earth content) are plotted as a trend of garnet composition in the grossular–andradite–Ti-andradite series. Garnets from silicate-carbonate rocks, unlike those from skarn mineral associations, are characterized by an increased rare-earth elements content. The main feature of the rare-earth elements distribution spectra in garnets is a positive Eu-anomaly, which is observed in all studied garnets.   Conclusion. The data obtained allowed the authors to assume that garnets from silicate-carbonate formations and their halos were formed as a result of a single geological process, essentially close to skarn formation. The results of the petrographic-mineralogical and geochemical studies assume that the “carbonatite” nature of the silicate-carbo nate rocks of the Southern Urals is unlikely.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"12 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78635580","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}

{"title":"Typification of clay-siliceous deposits of the Berezovskaya formation (on the example of wells of the Kharampurskoye field)","authors":"E. S. Klimova, K. N. Chertina, M. A. Alexandrov, A. V. Solovieva, N. N. Arzhilovskaya","doi":"10.24930/1681-9004-2023-23-2-197-208","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-197-208","url":null,"abstract":"   Research subject. Clay-siliceous deposits of the Berezovskaya formation of the Cognac-Santon-Campanian age in three wells of the Kharampur deposit.   Aim. To study the mineral and structural characteristics of the flint matrix for the separation of flint rocks into lithotypes, namely, silicites and flakes per se.   Methods. X-ray diffraction analysis and scanning electron microscopy.   Results and conclusions. The main criteria for the separation of flint rocks include the content of the opal-cristoballite-tridimite phase and its structural state, which is quantitatively characterized by the coefficient of structural perfection K (according to the X-ray diffraction) and, at the qualitative level, is confirmed by the difference in its morpholo gical types (according to the scanning electron microscopy). The relationship between the porosity of flint rocks and the sili con matrix microstructure was also established.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84357148","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}

{"title":"Kedzydshor Formation and conodonts of the Lower Frasnian on the Izyayu River (South of the Tchernyshev Uplift)","authors":"M. A. Soboleva, Andrey V. Zhuravlev","doi":"10.24930/1681-9004-2023-23-2-151-164","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-151-164","url":null,"abstract":"   Research subject. Conodonts of the Lower Frasnian Kedzydshor Formation of the southern part of the Tchernyshev Uplift.   Materials and methods. Materials obtained during a study of the section of the Kedzydshor Formation located on the Izyayu River were used. The biostratigraphic subdivision of the section was based on taxonomic definitions of conodonts and correlations with the Standard and Frasnian conodont zones.   Results. In comparison with the stratotype of the Kedzydshor Formation, carbonate-argillaceous deposits cropping out on the Izyayu River are represented by fragments of the middle and upper parts of the Kedzydshor Formation in the stratigraphic range of the Lower falsiovalis Zone of the standard conodont zonation of the Lower Frasnian. The predominantly carbonate interval of the section is conventionally correlated with the FZ1 conodont zone, while the overlying terrigenous interval – with FZ2. The polygnatid and polygnatid-ancyrodellid conodont biofacies dominate in the section under study.   Conclusions. New data on the distribution of cono donts across the Kedzydshor Formation in the Izyayu River section were obtained. The obtained data were compared with the local stratigraphic units of the Timan-North Urals Region. The Kedzydshor Formation is one of the most complete sequences of the Middle-Upper Devonian transition, thus representing the basis for searching and substantiating the position of the debatable lower boundary of the Frasnian Stage of the Upper Devonian.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"79 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83921331","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}

{"title":"Geology, morphology and mineralogy of sulfide-carbonate hydrothermal-bacterial structures on the surface of Tessel paleovolcano lava (south coast of Crimea)","authors":"V. Lysenko, V. Kotlyarov, T. V. Mihaylichenko","doi":"10.24930/1681-9004-2023-23-2-179-196","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-179-196","url":null,"abstract":"   Research subject. Sulfide-carbonate hydrothermal-bacterial structures on the surface of Tessel paleovolcano lava.   Materials and methods. The structures under study were found during detailed geological works. Petrographic thin sections were studied using an Olympus Bx5 microscope. Carbonate and sulfide samples were examined using an RZMMA-202M scanning electron microscope.   Results. For the first time, the contacts of the studied structures with their enclosing siltstones and mudstones were described. The structures are of tubular and flat shapes. In terms of mineral composition, the structures exhibit three zones: central, lateral and that of bacterial overgrowth. The middle part of the central zone features a fluid channel with inclusions of quartz, barite, nakrite, galena, chalcopyrite, pyrrhotite, sphalerite, pyrite, shells of largefauna, ash and tuff material. Spherulites and microtubular carbonate formations testify to the participation of bacterial and archaean communities in the construction process. The study of carbonates and sulfides confirmed the use of deep fluids by prokaryotes.   Conclusion. The main role in the formation of the sulfide-carbonate hydrothermal-bacterial structures under study belonged to the community of prokaryotes and fluids from the depths. The external morphology of the studied structures along with the presence of mineralogical zonality, a fluid channel, oil products, and oases of life with a large fauna indicate the similarity of their formation conditions to those of sulfide-carbonate smokers of the Piip volcano. Some differences in the mineral composition are associated with different depths and fluids of their formation.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"35 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74663902","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}

{"title":"Forms of presence, interrelation and genetic significance of Al and Li impurities in quartz of gold deposits of the Darasunsky ore field (Eastern Transbaikalia, Russia)","authors":"L. Rakov, V. Prokofiev, E. Minervina, L. D. Zorina","doi":"10.24930/1681-9004-2023-23-2-209-224","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-209-224","url":null,"abstract":"   Research subject. The distribution regularities of Al and Li impurities in gold-ore quartz.   Materials and methods. The quartz of the Darasun, Teremkinskoye and Talatuy gold deposits of the Darasun ore field was studied. The gross contents of Al and Li impurities in quartz were determined by the LA-ICP-MS method; substitutional Al impurity concentrations were studied by the EPR method. The forms of Al impurity in quartz were determined based on the results of studying its behavior during material recrystallization. The genetic significance of Al and Li impurities in quartz was estimated taking into account the genetic information obtained during the study of the distribution of substitutional Al and Ti impurity concentrations.   Results. It was found that Al is present in quartz in two main forms, i. e., as a substitutional Al impurity and Al complexes localized in the areas of high mineral defectiveness. Li+ ions are located in the structural channels of the mineral, serving as compensating ions for both Al impurity forms. The composition of Al complexes is assumed to include three Al3+ ions and one H+ or Li+ ion. Two stages of quartz recrystallization occurring at different temperatures of mineral formation were identified. The first, low-temperature stage leads to quartz enrichment with substitutional Al impurities. The second, high-temperature stage causes the decomposition of Al complexes. The recrystallization stages can be identified by the type of relationship between the gross concentrations of Al and Li. The increased content of Al impurity in ore quartz was found to be related to the presence of a large number of Al complexes. An assumption is made that these complexes formed during mineral crystallization from solutions with a high content of metal ions.   Conclusions. The results obtained indicate that high Al impurity concentrations can serve as a genetic sign of ore quartz. At the same time, the decomposition of Al complexes during quartz recrystallization should be taken into account. A method for estimating the initial concentration of Al complexes is proposed, which is a more reliable genetic indicator.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"59 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90751937","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}

{"title":"Famennian negative carbon isotope excursion in the Izyayu River section (Tchernyshev Uplift, Cis-Uralian Foredeep)","authors":"D. Gruzdev, Andrey V. Zhuravlev, Y. Vevel, A. V. Erofeevsky, I. Smoleva","doi":"10.24930/1681-9004-2023-23-2-165-178","DOIUrl":"https://doi.org/10.24930/1681-9004-2023-23-2-165-178","url":null,"abstract":"   Research subject. The article is focused on manifestations of the Early-Middle Famennian negative excursion in carbon isotope composition in the Izyayu River section (south of the Tchernyshev Uplift).   Aim. The study is aimed to reconstructing of the probable causes of this isotope excursion.   Materials and methods. The article is based on the results of study of the deep-shelf lower-middle Famennian sequence of the Izyayu River section. The carbon isotopic composition was studied for the carbonate samples and conodont elements (32 and 9 samples respectively).   Results. The lightening of the carbon isotopic composition of carbonates by 2.5 %, and of the carbon isotopic composition of conodont elements by 4 % were found in the Pal. gracilis gracilis–Pal. marginifera marginifera zonal interval. The difference between the carbon isotopic compositions of carbonates and conodont elements increases in this interval by more than 2.5 %. Possible reasons for the observed variations could be the intensification of terrigenous runoff due to regression, a relatively high content of carbon dioxide in the atmosphere, and, possibly, a local decline in primary bioproductivity.   Conclusions. The negative carbon isotope shift spans Pal. gracilis gracilis–Pal. marginifera marginifera zonal interval in the Izyayu River section. The shift corresponds to the global decreasing in the δ13Ccarb values in the early/middle Famennian boundary interval. The increase in supply of the isotopically light carbon with terrigenous runoff and decrease in the primary bioproductivity are considered as probable causes of the carbon isotope excursion.","PeriodicalId":18202,"journal":{"name":"LITHOSPHERE (Russia)","volume":"110 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85763884","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}