E.V. Sokol, A. S. Deviatiiarova, A. Pyryaev, T. Bul’bak, A. Tomilenko, Yu.V. Seretkin, I.V. Pekov, A. V. Nekipelova, P. Khvorov
––Carbon and oxygen isotope compositions have been determined in (CO3)-groups of Ca carbonate–silicate minerals (spurrite, tilleyite, and scapolite) and calcite from samples of the Kochumdek contact aureole (East Siberia). The observed small δ13C and δ18O difference between the Kochumdek marbles and their protoliths (Δδ13C ≤ 1.5‰ and Δδ18O ≤ 2.0‰) is consistent with moderate high-temperature metamorphic decarbonation of the protolith (0.1–0.2) and with almost absent metasomatic alteration in the aureole. Significant 18O depletion was inferred only for vein scapolite (δ18O from +17.0 to +17.3‰ V-SMOW) and calcite from recrystallized limestone layers (δ18O from +18.9 to +20.6‰), which is evidence for limited infiltration of magmatic aqueous fluids from the cooling sill into the host sediments. The C and O isotope compositions of (CO3)-bearing spurrite and tilleyite show lower 18O depletion and insignificant 13C depletion relative to calcite, especially in highest-temperature merwinite marble (Δδ18OSpu–Cal = +3.3‰; Δδ13CSpu–Cal = –0.8‰). Gas chromatography-mass spectrometry (GC-MS) provided constraints on the relative percentages of H2O and CO2 in the fluid at highest-temperature spurrite-merwinite metamorphism. The fluid phase entrapped in calcite from merwinite marble is rich in CO2(XCO2=0.4−0.6).
--测定了科楚姆德克接触弧（东西伯利亚）样品中碳酸钙硅酸盐矿物（尖晶石、钛铁矿和霞石）和方解石的（CO3）组碳和氧同位素组成。观测到的 Kochumdek 大理石与其原岩之间的 δ13C 和 δ18O 差异很小（Δδ13C ≤ 1.5‰，Δδ18O ≤ 2.0‰），这与原岩的中度高温变质脱碳（0.1-0.2）以及金口几乎不存在变质蚀变相吻合。只有脉闪长岩（δ18O从+17.0到+17.3‰ V-SMOW）和重结晶石灰岩层的方解石（δ18O从+18.9到+20.6‰）推断出了18O的显著损耗，这证明了岩浆水流从冷却的山体向主沉积物的有限渗透。与方解石相比，含（CO3）的尖晶石和透辉石的 C 和 O 同位素组成显示出较低的 18O 损耗和不明显的 13C 损耗，尤其是在温度最高的梅花石大理岩中（Δδ18OSpu-Cal = +3.3‰；Δδ13CSpu-Cal = -0.8‰）。气相色谱-质谱法（GC-MS）对最高温度尖晶石-闪长岩变质时流体中 H2O 和 CO2 的相对比例提供了约束。梅花石大理岩方解石中夹带的流体相富含二氧化碳（XCO2=0.4-0.6）。
{"title":"Carbon and Oxygen Stable Isotopes in Isochemical Contact Metamorphism (Case Study of the Kochumdek Aureole, East Siberia)","authors":"E.V. Sokol, A. S. Deviatiiarova, A. Pyryaev, T. Bul’bak, A. Tomilenko, Yu.V. Seretkin, I.V. Pekov, A. V. Nekipelova, P. Khvorov","doi":"10.2113/rgg20234545","DOIUrl":"https://doi.org/10.2113/rgg20234545","url":null,"abstract":"\u0000 ––Carbon and oxygen isotope compositions have been determined in (CO3)-groups of Ca carbonate–silicate minerals (spurrite, tilleyite, and scapolite) and calcite from samples of the Kochumdek contact aureole (East Siberia). The observed small δ13C and δ18O difference between the Kochumdek marbles and their protoliths (Δδ13C ≤ 1.5‰ and Δδ18O ≤ 2.0‰) is consistent with moderate high-temperature metamorphic decarbonation of the protolith (0.1–0.2) and with almost absent metasomatic alteration in the aureole. Significant 18O depletion was inferred only for vein scapolite (δ18O from +17.0 to +17.3‰ V-SMOW) and calcite from recrystallized limestone layers (δ18O from +18.9 to +20.6‰), which is evidence for limited infiltration of magmatic aqueous fluids from the cooling sill into the host sediments. The C and O isotope compositions of (CO3)-bearing spurrite and tilleyite show lower 18O depletion and insignificant 13C depletion relative to calcite, especially in highest-temperature merwinite marble (Δδ18OSpu–Cal = +3.3‰; Δδ13CSpu–Cal = –0.8‰). Gas chromatography-mass spectrometry (GC-MS) provided constraints on the relative percentages of H2O and CO2 in the fluid at highest-temperature spurrite-merwinite metamorphism. The fluid phase entrapped in calcite from merwinite marble is rich in CO2(XCO2=0.4−0.6).","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"442 ","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139011245","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}
I. Gubin, A. Kontorovich, L. Burshtein, L.N. Konstatinova, E.N. Kuznetsova, S. A. Moiseev, P. I. Safronov
––This study presents the results of recent regional seismic exploration and deep drilling efforts in the Sayan–Yenisei syneclise and adjacent areas of the Lena–Tunguska petroleum province. These results were used to build a series of structure maps for Riphean, Vendian and Lower Cambrian reflectors; thickness maps of the Riphean and Vendian terrigenous geoseismic sequences within the syneclise, and a tectonic map of the Vendian–Paleozoic structural stage of the Sayan–Yenisei syneclise. The proposed oil and gas geological zoning of the Sayan–Yenisei potential petroleum area enabled us to identify eight potential petroleum regions and perform a quantitative assessment of the hydrocarbon potential. The original in-place resources of the Sayan–Yenisei potential petroleum area are estimated to be 3 billion 231 mln tons of hydrocarbon equivalent, including 3 trillion 39 billion m3 of gas and 192.7 mln tons of condensate. It is shown that over next 15–20 years, up to 1 trillion m3 gas reserves can be explored in the Sayan–Yenisei potential petroleum area. It is proposed to consider the Boguchany village as a large gas conversion and helium production center.
{"title":"Sayan–Yenisei Potential Petroleum Area and Its Resource Potential","authors":"I. Gubin, A. Kontorovich, L. Burshtein, L.N. Konstatinova, E.N. Kuznetsova, S. A. Moiseev, P. I. Safronov","doi":"10.2113/rgg20234604","DOIUrl":"https://doi.org/10.2113/rgg20234604","url":null,"abstract":"\u0000 ––This study presents the results of recent regional seismic exploration and deep drilling efforts in the Sayan–Yenisei syneclise and adjacent areas of the Lena–Tunguska petroleum province. These results were used to build a series of structure maps for Riphean, Vendian and Lower Cambrian reflectors; thickness maps of the Riphean and Vendian terrigenous geoseismic sequences within the syneclise, and a tectonic map of the Vendian–Paleozoic structural stage of the Sayan–Yenisei syneclise. The proposed oil and gas geological zoning of the Sayan–Yenisei potential petroleum area enabled us to identify eight potential petroleum regions and perform a quantitative assessment of the hydrocarbon potential. The original in-place resources of the Sayan–Yenisei potential petroleum area are estimated to be 3 billion 231 mln tons of hydrocarbon equivalent, including 3 trillion 39 billion m3 of gas and 192.7 mln tons of condensate. It is shown that over next 15–20 years, up to 1 trillion m3 gas reserves can be explored in the Sayan–Yenisei potential petroleum area. It is proposed to consider the Boguchany village as a large gas conversion and helium production center.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"5 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138602909","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}
Abstract ––The Aeronian clastic sediments in the Gorny Altai area bear signatures of past seismic effects (paleo-seismites). Sedimentary structures produced by brittle deformation (breccias) span the level of the upper convolutus graptolite zone and the lower sedgwicki zone. They coexist with soft-sediment deformation structures (SSDS), such as turbated and rolled layers, bumpy layer boundaries, etc. At the final deposition stage, the rocks were deformed during seismically-triggered landsliding and were shed into a submarine canyon, with formation of rolls (pseudo-conglomerate).
{"title":"Signatures of Syndepositional Seismic Effects in Aeronian Marine Clastic Sediments in Western Gorny Altai","authors":"N.V. Sennikov","doi":"10.2113/rgg20234615","DOIUrl":"https://doi.org/10.2113/rgg20234615","url":null,"abstract":"Abstract ––The Aeronian clastic sediments in the Gorny Altai area bear signatures of past seismic effects (paleo-seismites). Sedimentary structures produced by brittle deformation (breccias) span the level of the upper convolutus graptolite zone and the lower sedgwicki zone. They coexist with soft-sediment deformation structures (SSDS), such as turbated and rolled layers, bumpy layer boundaries, etc. At the final deposition stage, the rocks were deformed during seismically-triggered landsliding and were shed into a submarine canyon, with formation of rolls (pseudo-conglomerate).","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" 29","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135187125","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}
Abstract —Primary melt and fluid inclusions in quartz and dalyite of calcite–quartz carbonatitoids of the Murun massif have been studied. They contain CO2, N2, CH4, C2H6, C3H8, H2, and H2S as well as sulfates and hydrocarbonates as solid daughter phases. The inclusion solutions contain HS- and chlorides. In addition, disordered carbon and bitumen are present. It is concluded that the magmatic fluid phase that was in equilibrium with quartz was characterized by a predominantly H2O–CO2–H2S composition and a reduced state. This explains the appearance of sulfides at the magmatic stage of crystallization of calcite–quartz carbonatitoids of the Murun massif. We substantiate the hypothesis that the sulfates, hydrocarbons, and H2 detected in the inclusions form at decreasing temperature as a result of shift of the redox equilibrium.
{"title":"Fluid Regime of Crystallization of the Calcite–Quartz Carbonatitoids of the Murun Massif","authors":"I.A. Sotnikova, A.A. Borovikov, T.B. Kolotilina, N.V. Alymova","doi":"10.2113/rgg20234611","DOIUrl":"https://doi.org/10.2113/rgg20234611","url":null,"abstract":"Abstract —Primary melt and fluid inclusions in quartz and dalyite of calcite–quartz carbonatitoids of the Murun massif have been studied. They contain CO2, N2, CH4, C2H6, C3H8, H2, and H2S as well as sulfates and hydrocarbonates as solid daughter phases. The inclusion solutions contain HS- and chlorides. In addition, disordered carbon and bitumen are present. It is concluded that the magmatic fluid phase that was in equilibrium with quartz was characterized by a predominantly H2O–CO2–H2S composition and a reduced state. This explains the appearance of sulfides at the magmatic stage of crystallization of calcite–quartz carbonatitoids of the Murun massif. We substantiate the hypothesis that the sulfates, hydrocarbons, and H2 detected in the inclusions form at decreasing temperature as a result of shift of the redox equilibrium.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":" 349","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135186641","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}
Abstract —The way towards the stage subdivision of the Vendian starts with the assemblage of a complete composite geological section of this interval of the Earth’s history, a succession of geological bodies each reflecting a certain ecosystem state. A Vendian composite section of the Siberian Platform, which is a succession of regional to sub-global scale geological bodies reflecting particular states or unidirectional transformations determined by episodic expansion of relatively oxygen-rich environments onto the shelf and alternating with large-scale oceanic anoxia and euxinia events is proposed as a reference for constructing the stage subdivision of the Vendian. The redox instability had to be accompanied by changes in nutrient availability and could not but affect the course of macroevolution and macroecology. The geological record of the Vendian of the Siberian Platform is also marked by episodic increase in alkalinity of the World Ocean. At least five such alkalinity events could be provisionally identified in the composite section of the Vendian of the Siberian Platform. A hypothesis is proposed suggesting that the alkalinity events could control the appearance and disappearance in the geological record of a distinctive suite of sedimentary structures in carbonates, the discrete nature of early diagenetic cementation of aluminosilicoclastic sediments, and fossilization of soft-bodied organisms in the Vendian.
{"title":"Towards Stage Subdivision of the Vendian","authors":"D.V. Grazhdankin, D.O. Aleksandrov, V.O. Maksimenko, V.I. Rogov","doi":"10.2113/rgg20234636","DOIUrl":"https://doi.org/10.2113/rgg20234636","url":null,"abstract":"Abstract —The way towards the stage subdivision of the Vendian starts with the assemblage of a complete composite geological section of this interval of the Earth’s history, a succession of geological bodies each reflecting a certain ecosystem state. A Vendian composite section of the Siberian Platform, which is a succession of regional to sub-global scale geological bodies reflecting particular states or unidirectional transformations determined by episodic expansion of relatively oxygen-rich environments onto the shelf and alternating with large-scale oceanic anoxia and euxinia events is proposed as a reference for constructing the stage subdivision of the Vendian. The redox instability had to be accompanied by changes in nutrient availability and could not but affect the course of macroevolution and macroecology. The geological record of the Vendian of the Siberian Platform is also marked by episodic increase in alkalinity of the World Ocean. At least five such alkalinity events could be provisionally identified in the composite section of the Vendian of the Siberian Platform. A hypothesis is proposed suggesting that the alkalinity events could control the appearance and disappearance in the geological record of a distinctive suite of sedimentary structures in carbonates, the discrete nature of early diagenetic cementation of aluminosilicoclastic sediments, and fossilization of soft-bodied organisms in the Vendian.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"248 1-2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135566383","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}
Abstract —This special issue is dedicated to discussing the possibility of the stage division of the Vendian system, specifically, a composite section of the Siberian Platform is proposed as a stratigraphic standard. For the Ordovician system of the Siberian Platform and Northeastern Russia, certain changes in stratigraphic charts are proposed, nomenclative issues and different variants of correlations of regional horizons with the General Stratigraphic Scale (GSS) of Russia are considered. A geochemical analysis of Bajocian and Bathonian belemnite rostra of Arctic Siberia was carried out and for the first time a comprehensive C, O, and Sr isotope characterization of the sections was obtained, making it possible to propose a comparison of the studied sections with the European standard and to develop paleogeographic models. Comprehensive studies of the Upper Jurassic and Lower Cretaceous series of the Anabar Bay deposits (Laptev Sea) led to an improved biostratigraphic division for this reference section and to the identification of the levels for interregional and global correlation. The magnetostratigraphic division of the Jurassic–Cretaceous boundary interval and its comparison with the Tethyan regions are discussed. Taking into account biostratigraphic data, the δ13Corg variation curve can also serve as a correlation tool. The clinoform structure of Upper Jurassic strata was revealed in the northwest of the Anabar–Khatanga depression, based on the interpretation of seismic profiles calibrated against studied sections. The formation of this complex allows us to consider this stage as the initiation of the Verkhoyan orogeny in this folded area. Analysis of variations in the thickness of sediments allows us to deduce that intense tectonic-sedimentary processes took place during the Late Jurassic epoch, along with subsidence of the bed of the sedimentary basin. Analysis of a specific assemblage of lacustrine fossils from the reference section of the upper part of the Lower Cretaceous series of Transbaikalia and of published data showed that this fossil assemblage was widespread in East Asia. Biofacies analysis made it possible to reconstruct the paleoenvironments of this time.
{"title":"Paleontology, Stratigraphy and Biogeography of the Late Precambrian and Phanerozoic Formations of Russia","authors":"A.E. Kontorovich, B.L. Nikitenko","doi":"10.2113/rgg20234694","DOIUrl":"https://doi.org/10.2113/rgg20234694","url":null,"abstract":"Abstract —This special issue is dedicated to discussing the possibility of the stage division of the Vendian system, specifically, a composite section of the Siberian Platform is proposed as a stratigraphic standard. For the Ordovician system of the Siberian Platform and Northeastern Russia, certain changes in stratigraphic charts are proposed, nomenclative issues and different variants of correlations of regional horizons with the General Stratigraphic Scale (GSS) of Russia are considered. A geochemical analysis of Bajocian and Bathonian belemnite rostra of Arctic Siberia was carried out and for the first time a comprehensive C, O, and Sr isotope characterization of the sections was obtained, making it possible to propose a comparison of the studied sections with the European standard and to develop paleogeographic models. Comprehensive studies of the Upper Jurassic and Lower Cretaceous series of the Anabar Bay deposits (Laptev Sea) led to an improved biostratigraphic division for this reference section and to the identification of the levels for interregional and global correlation. The magnetostratigraphic division of the Jurassic–Cretaceous boundary interval and its comparison with the Tethyan regions are discussed. Taking into account biostratigraphic data, the δ13Corg variation curve can also serve as a correlation tool. The clinoform structure of Upper Jurassic strata was revealed in the northwest of the Anabar–Khatanga depression, based on the interpretation of seismic profiles calibrated against studied sections. The formation of this complex allows us to consider this stage as the initiation of the Verkhoyan orogeny in this folded area. Analysis of variations in the thickness of sediments allows us to deduce that intense tectonic-sedimentary processes took place during the Late Jurassic epoch, along with subsidence of the bed of the sedimentary basin. Analysis of a specific assemblage of lacustrine fossils from the reference section of the upper part of the Lower Cretaceous series of Transbaikalia and of published data showed that this fossil assemblage was widespread in East Asia. Biofacies analysis made it possible to reconstruct the paleoenvironments of this time.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"247 1-2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135566384","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}
Abstract —New materials on the stratigraphy and structural features of the Bathonian–Neocomian sections of the Anabar–Lena basin are presented. In the territory adjacent to the Taimyr mountain-folded system, a clinoform-like structure of the Upper Jurassic strata has been revealed, which are characterized by high thickness compared to adjacent sections in the east of this region. The lectostratotype of the Chernokhrebetnaya Formation (uppermost Lower Oxfordian–lowermost Volgian) is proposed. The most complete and continuous stratigraphic section is compiled, its litho- and chronostratigraphic correlations are given comparing to the sections of adjacent territories characterized in detail by fossil assamblages. The evidences for a new lithostratigraphic division of the territory are provided, facies zoning of sediments is clarified, a thickness chart of the Upper Bathonian–Boreal Berriasian strata of the Khatanga–Olenek interfluve is proposed.
{"title":"Stratigraphy and Sedimentogenesis of the Clinoform Upper Jurassic of the Anabar–Lena Sedimentary Basin (Arctic Siberia, Laptev Sea Coast)","authors":"V.P. Devyatov, B.L. Nikitenko","doi":"10.2113/rgg20234620","DOIUrl":"https://doi.org/10.2113/rgg20234620","url":null,"abstract":"Abstract —New materials on the stratigraphy and structural features of the Bathonian–Neocomian sections of the Anabar–Lena basin are presented. In the territory adjacent to the Taimyr mountain-folded system, a clinoform-like structure of the Upper Jurassic strata has been revealed, which are characterized by high thickness compared to adjacent sections in the east of this region. The lectostratotype of the Chernokhrebetnaya Formation (uppermost Lower Oxfordian–lowermost Volgian) is proposed. The most complete and continuous stratigraphic section is compiled, its litho- and chronostratigraphic correlations are given comparing to the sections of adjacent territories characterized in detail by fossil assamblages. The evidences for a new lithostratigraphic division of the territory are provided, facies zoning of sediments is clarified, a thickness chart of the Upper Bathonian–Boreal Berriasian strata of the Khatanga–Olenek interfluve is proposed.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"104 5","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135564947","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}
Abstract —The age of the Turga Formation in the Middendorf’s outcrop is determined as latest Barremian–earliest Aptian based on fauna and microfossil assemblages. The composition of the fauna and palynomorph assemblages allows correlations between the Turga Formation and the Yixian Formation and lower part of the Jiufotang Formation of Northeast China. Results of the petrographic and geochemical analysis as well as microfossil studies showed that sediments accumulated in a shallow lake with low-energy hydrodynamics, sometimes under low-oxygen conditions. Climate features (warm temperate climate transitional to subtropical) and type of vegetation (coniferous forests with admixture of hardwoods) are reconstructed taking into consideration the composition of spore-pollen assemblages.
{"title":"Turga Lagerstätte (Middendorf’s Outcrop, Eastern Transbaikalia, Barremian–Aptian): Stratigraphic Range and Palaeoenvironments","authors":"I.N. Kosenko, E.B. Pestchevitskaya, V.D. Efremenko, E.K. Metelkin, P.A. Yan, A.P. Rodchenko, B.L. Nikitenko, D.A. Mirzabaev","doi":"10.2113/rgg20234625","DOIUrl":"https://doi.org/10.2113/rgg20234625","url":null,"abstract":"Abstract —The age of the Turga Formation in the Middendorf’s outcrop is determined as latest Barremian–earliest Aptian based on fauna and microfossil assemblages. The composition of the fauna and palynomorph assemblages allows correlations between the Turga Formation and the Yixian Formation and lower part of the Jiufotang Formation of Northeast China. Results of the petrographic and geochemical analysis as well as microfossil studies showed that sediments accumulated in a shallow lake with low-energy hydrodynamics, sometimes under low-oxygen conditions. Climate features (warm temperate climate transitional to subtropical) and type of vegetation (coniferous forests with admixture of hardwoods) are reconstructed taking into consideration the composition of spore-pollen assemblages.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"56 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134996056","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}
Abstract —In the Middle Ordovician sections of the Eriekhe River basin, which are of crucial importance to correlate the regional stratigraphic units of Northeast Russia and the General Stratigraphic Scale (by graptolites), we identified a diverse ostracod assemblage. The new data substantially supplement the Middle Ordovician paleontology of this region. The analysis of the stratigraphic distribution of these assemblages made it possible to verify the correlation of the Eriekhe Structural Facies Zone (SFZ) suites with regional stratigraphic units of the Northeast Russia and, based on homotypic ostracod assemblages, with the horizons of the Siberian Platform. The joint findings of ostracods and graptolites in the studied section allowed us to correlate the horizons of the Northeast Russia and the Siberian platform with the stages of the General Stratigraphic Scale.
{"title":"Ostracods and Interregional Correlation between the Ordovician Sections of Northeast Russia (Eriekhe River Basin) and the Siberian Platform","authors":"T.V. Gonta, A.V. Kanygin, R.F. Sobolevskaya","doi":"10.2113/rgg20234599","DOIUrl":"https://doi.org/10.2113/rgg20234599","url":null,"abstract":"Abstract —In the Middle Ordovician sections of the Eriekhe River basin, which are of crucial importance to correlate the regional stratigraphic units of Northeast Russia and the General Stratigraphic Scale (by graptolites), we identified a diverse ostracod assemblage. The new data substantially supplement the Middle Ordovician paleontology of this region. The analysis of the stratigraphic distribution of these assemblages made it possible to verify the correlation of the Eriekhe Structural Facies Zone (SFZ) suites with regional stratigraphic units of the Northeast Russia and, based on homotypic ostracod assemblages, with the horizons of the Siberian Platform. The joint findings of ostracods and graptolites in the studied section allowed us to correlate the horizons of the Northeast Russia and the Siberian platform with the stages of the General Stratigraphic Scale.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"101 ","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136306784","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}
Abstract —The chronozonal structure of the Mangazeya Superhorizon of Eastern Siberia, which includes the Listvyazhny and Baksan horizons and their chronozones, is considered. Their volumes and stratotypes are given and their place in the regional and global stratigraphic structure is shown, where Mangazeya occupies the middle parts of the Kuzmovsky regional complex and the Caradocian stage of the Upper Ordovician. Proper names for the Lower Dolbor Horizon (Amutkansky) and the Upper Dolbor Horizon (Cherlechinsky) are introduced for the first time.
{"title":"Chronozonal Structure of the Mangazeya Superhorizon in Eastern Siberia and Its Place in the Global Ordovician Scale","authors":"Yu.I. Tesakov","doi":"10.2113/rgg20234614","DOIUrl":"https://doi.org/10.2113/rgg20234614","url":null,"abstract":"Abstract —The chronozonal structure of the Mangazeya Superhorizon of Eastern Siberia, which includes the Listvyazhny and Baksan horizons and their chronozones, is considered. Their volumes and stratotypes are given and their place in the regional and global stratigraphic structure is shown, where Mangazeya occupies the middle parts of the Kuzmovsky regional complex and the Caradocian stage of the Upper Ordovician. Proper names for the Lower Dolbor Horizon (Amutkansky) and the Upper Dolbor Horizon (Cherlechinsky) are introduced for the first time.","PeriodicalId":49587,"journal":{"name":"Russian Geology and Geophysics","volume":"48 2","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135111574","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}
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