I. Nuzhdaev, S. Rychagov, S. Feofilaktov, Y. Bukatov
––Based on integrated structural and geophysical studies and generalization of geophysical, hydrogeological, mineralogical, geochemical and other data, it is shown that the southern cluster of thermal fields of the Kambalny volcanic ridge (South Kamchatka) is included in the modern hydrothermal system. New data on the structure of the steam hydrotherm discharge area investigated to a depth of about 300 m have been obtained. The structural and hydrodynamic connection between two thermal fields from this group has been established. The Kambalny Ridge geothermal system embracing all major clusters of thermal fields is assumed to have a single deep-seated source of heat supply.
{"title":"Structure of the Hydrothermal System of Thermal Fields Inferred from Geological-Geophysical Modeling: A Case Study of the Kambalny Volcanic Ridge (Kamchatka)","authors":"I. Nuzhdaev, S. Rychagov, S. Feofilaktov, Y. Bukatov","doi":"10.2113/rgg20234608","DOIUrl":"https://doi.org/10.2113/rgg20234608","url":null,"abstract":"\u0000 ––Based on integrated structural and geophysical studies and generalization of geophysical, hydrogeological, mineralogical, geochemical and other data, it is shown that the southern cluster of thermal fields of the Kambalny volcanic ridge (South Kamchatka) is included in the modern hydrothermal system. New data on the structure of the steam hydrotherm discharge area investigated to a depth of about 300 m have been obtained. The structural and hydrodynamic connection between two thermal fields from this group has been established. The Kambalny Ridge geothermal system embracing all major clusters of thermal fields is assumed to have a single deep-seated source of heat supply.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":" 90","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140685157","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}
—In this work, based on structural and phase analysis data, we consider the behavior of Au nanoparticles (NP) during the formation of interphase boundaries between quartz and copper and iron selenides upon annealing at 450 °C and different selenium activities: lgfSe2=−2.4 with a melted selenium buffer and lgfSe2=−3.15 according to the indications of the indicator mineral mixture γ–Fe1–xSe and δ–Fe1–xSe. In two series of experiments, contrasting textural features (nano- and microstates) of the initial metal phases were used, which made it possible to construct 2D and 3D models of interphase boundaries. In the first case, thin layers of gold NPs (~30 nm thick), iron (~50 nm thick), and copper (~50 nm thick) were deposited onto quartz crystals less than 40 μm in size by magnetron sputtering, i.e., all metals were in a nanosized state. In the second case, iron, copper, and selenium (in eskebornite stoichiometry – CuFeSe2) were introduced into the system in the form of micron-sized powder materials (1–10 microns). Gold still remained in the form of NPs on the quartz surface. The thermal annealing products were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, and X-ray photoelectron spectroscopy (XPS). The study showed that, regardless of the activity of selenium, annealing of Au NPs leads to partial enlargement of particles (up to submicron sizes) based on the self-assembly mechanism (the size distribution of Au particles corresponds to a lognormal law with a maximum shifted towards smaller sizes), and gold remains in the metallic state. The 2D model of the interphase boundary is a mineral mixture of copper selenides (Cu2Se), iron (γ–Fe1–xSe) and islands of submicron gold particles formed on the surface of quartz. The 3D model of the interphase boundary is characterized by the fact that Au particles are concentrated mainly in eskebornite, and not on the quartz surface. Moreover, NPs are localized in the pores of mesoporous eskebornite, and submicron particles with a size of ~ 200 nm or more are displaced to the surface of eskebornite particles. Based on the data obtained, typomorphic features of the presence of Au NPs in the ore-forming processes of the formation and development of gold ore deposits are formulated.
{"title":"Behavior of Gold Nanoparticles at the Interphase Boundary of Quartz–Selenide Copper and Iron at a Temperature of 450 °C and Different Selenium Activity","authors":"V.V. Akimov, D. Babkin, O. Belozerova","doi":"10.2113/rgg20244691","DOIUrl":"https://doi.org/10.2113/rgg20244691","url":null,"abstract":"\u0000 —In this work, based on structural and phase analysis data, we consider the behavior of Au nanoparticles (NP) during the formation of interphase boundaries between quartz and copper and iron selenides upon annealing at 450 °C and different selenium activities: lgfSe2=−2.4 with a melted selenium buffer and lgfSe2=−3.15 according to the indications of the indicator mineral mixture γ–Fe1–xSe and δ–Fe1–xSe. In two series of experiments, contrasting textural features (nano- and microstates) of the initial metal phases were used, which made it possible to construct 2D and 3D models of interphase boundaries. In the first case, thin layers of gold NPs (~30 nm thick), iron (~50 nm thick), and copper (~50 nm thick) were deposited onto quartz crystals less than 40 μm in size by magnetron sputtering, i.e., all metals were in a nanosized state. In the second case, iron, copper, and selenium (in eskebornite stoichiometry – CuFeSe2) were introduced into the system in the form of micron-sized powder materials (1–10 microns). Gold still remained in the form of NPs on the quartz surface. The thermal annealing products were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses, and X-ray photoelectron spectroscopy (XPS). The study showed that, regardless of the activity of selenium, annealing of Au NPs leads to partial enlargement of particles (up to submicron sizes) based on the self-assembly mechanism (the size distribution of Au particles corresponds to a lognormal law with a maximum shifted towards smaller sizes), and gold remains in the metallic state. The 2D model of the interphase boundary is a mineral mixture of copper selenides (Cu2Se), iron (γ–Fe1–xSe) and islands of submicron gold particles formed on the surface of quartz. The 3D model of the interphase boundary is characterized by the fact that Au particles are concentrated mainly in eskebornite, and not on the quartz surface. Moreover, NPs are localized in the pores of mesoporous eskebornite, and submicron particles with a size of ~ 200 nm or more are displaced to the surface of eskebornite particles. Based on the data obtained, typomorphic features of the presence of Au NPs in the ore-forming processes of the formation and development of gold ore deposits are formulated.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"79 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140709306","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}
М.D. Тomshin, N. Pokhilenko, S. Gogoleva, A.L. Zemnukhov
––The generalized chemical composition data on the studied dolerites from the Vilyui–Markha dike swarm (Vilyui paleorift) allowed detecting geochemically anomalous areas among them. It has been found that percentage of TiO2 and a number of heavy rare-earth elements (Th, Ta, Hf, Y, Nd) in the dolerites of dikes located within the kimberlite fields show almost twofold increase compared to the normal content for these elements in the Vilyui–Markha dolerites. Similar behavior of these elements is also observed in the dolerite dikes near the Kuoika kimberlite field (the Molodo dike swarm, Olenek paleorift). It is inferred that there is a connection between the increase in abundances of titanium and rare-earth elements in the dolerites and that the latter occur within the lithosphere blocks hosting kimberlite fields. The areas of lithospheric mantle roots linked with the formation of proto-kimberlites may have had bearing on the composition of tholeiite melt both in the processes of its generation and during its ascent to the Earth’s surface, which led to its local enrichment in titanium and a number of other elements. While the processes of the alignment of the geochemical composition between the high-titanium basites and the rest of the melt beyond the contours of the lithospheric blocks with kimberlite fields were weakly pronounced, they were responsible for appearance of zones enriched in titanium. Kimberlite fields that formed before or after basite magmas intrusion overlap with placements of high-titanium dolerite dikes. Thus, high-titanium dolerites in dike swarms (belts) can be used as one of the criteria for kimberlite searches. In view of the above, two new potential zones (Tenkelyakh and Kyulenke areas) for kimberlite exploration have been identified within the Vilyui–Markha dike swarm.
{"title":"Localization of High-Titanium Dolerites in Kimberlite Fields: Possible Causes and a New Criterion for Kimberlite Search","authors":"М.D. Тomshin, N. Pokhilenko, S. Gogoleva, A.L. Zemnukhov","doi":"10.2113/rgg20244680","DOIUrl":"https://doi.org/10.2113/rgg20244680","url":null,"abstract":"\u0000 ––The generalized chemical composition data on the studied dolerites from the Vilyui–Markha dike swarm (Vilyui paleorift) allowed detecting geochemically anomalous areas among them. It has been found that percentage of TiO2 and a number of heavy rare-earth elements (Th, Ta, Hf, Y, Nd) in the dolerites of dikes located within the kimberlite fields show almost twofold increase compared to the normal content for these elements in the Vilyui–Markha dolerites. Similar behavior of these elements is also observed in the dolerite dikes near the Kuoika kimberlite field (the Molodo dike swarm, Olenek paleorift). It is inferred that there is a connection between the increase in abundances of titanium and rare-earth elements in the dolerites and that the latter occur within the lithosphere blocks hosting kimberlite fields. The areas of lithospheric mantle roots linked with the formation of proto-kimberlites may have had bearing on the composition of tholeiite melt both in the processes of its generation and during its ascent to the Earth’s surface, which led to its local enrichment in titanium and a number of other elements. While the processes of the alignment of the geochemical composition between the high-titanium basites and the rest of the melt beyond the contours of the lithospheric blocks with kimberlite fields were weakly pronounced, they were responsible for appearance of zones enriched in titanium. Kimberlite fields that formed before or after basite magmas intrusion overlap with placements of high-titanium dolerite dikes. Thus, high-titanium dolerites in dike swarms (belts) can be used as one of the criteria for kimberlite searches. In view of the above, two new potential zones (Tenkelyakh and Kyulenke areas) for kimberlite exploration have been identified within the Vilyui–Markha dike swarm.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"6 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140712283","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}
—Upper Devonian carbonate reef complexes have been studied on the territory of the Kolyvan-Tom’ Folded Area in sections in the right bank of Tom’ River. Facies analysis of the exposed part of the reef complex indicates the predominance of fore-reef and continental margin depositional environments of a tectonically active margin. The identified conodont associations are represented by cosmopolitan representatives of the genera Ancyrodella, Ancyrolepis, Icriodus, Mehlina, Palmatolepis, Polygnathus and “Polylophodonta” suggesting a correlation with the punctata–jamieae, rhenana–linguiformis, triangularis and Lower crepida conodont zones. The largest conodont diversity occurs at the triangularis/crepida boundary. Biofacies analysis of ostracod distribution has led to identification of characteristic associations and their restriction to certain parts of the palaeobasin. Substage boundaries yielded ostracods with both smooth and ornamented shells. In the lower part of the substages, smooth forms predominate, whereas the middle and upper parts of the substages are characterised by forms with tuberculate and reticulated surface. Hollinella valentinae Beds were traced in the Upper Frasnian Solomino Formation, and Acratia granuliformis Beds were traced in the Lower Famennian Kosoy Utyos and lower Mitikha members. Isotope geochemistry of the Upper Devonian sections of the south of Western Siberia reveals Frasnian global events – the Middlesex/punctata and the Upper Kellwasser, their stratigraphic position confirmed by palaeontological data, as well as by the globally expressed negative carbon isotope anomaly. These boundaries are marked by changes in depositional regime reflecting sea-level eustatic fluctuations, which are complemented with faunal changes.
{"title":"Bio-, Lithostratigraphic and Geochemical Markers of Global Events in the Upper Devonian of the South of Western Siberia and their Value for Inter-regional Correlations","authors":"O. Izokh, N. Izokh, B.M. Popov, S. V. Saraev","doi":"10.2113/rgg20244634","DOIUrl":"https://doi.org/10.2113/rgg20244634","url":null,"abstract":"\u0000 —Upper Devonian carbonate reef complexes have been studied on the territory of the Kolyvan-Tom’ Folded Area in sections in the right bank of Tom’ River. Facies analysis of the exposed part of the reef complex indicates the predominance of fore-reef and continental margin depositional environments of a tectonically active margin. The identified conodont associations are represented by cosmopolitan representatives of the genera Ancyrodella, Ancyrolepis, Icriodus, Mehlina, Palmatolepis, Polygnathus and “Polylophodonta” suggesting a correlation with the punctata–jamieae, rhenana–linguiformis, triangularis and Lower crepida conodont zones. The largest conodont diversity occurs at the triangularis/crepida boundary. Biofacies analysis of ostracod distribution has led to identification of characteristic associations and their restriction to certain parts of the palaeobasin. Substage boundaries yielded ostracods with both smooth and ornamented shells. In the lower part of the substages, smooth forms predominate, whereas the middle and upper parts of the substages are characterised by forms with tuberculate and reticulated surface. Hollinella valentinae Beds were traced in the Upper Frasnian Solomino Formation, and Acratia granuliformis Beds were traced in the Lower Famennian Kosoy Utyos and lower Mitikha members. Isotope geochemistry of the Upper Devonian sections of the south of Western Siberia reveals Frasnian global events – the Middlesex/punctata and the Upper Kellwasser, their stratigraphic position confirmed by palaeontological data, as well as by the globally expressed negative carbon isotope anomaly. These boundaries are marked by changes in depositional regime reflecting sea-level eustatic fluctuations, which are complemented with faunal changes.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"36 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140716588","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}
D. Bushnev, A. Ilchenko, L. V. Ogdanets, N. S. Burdel’naya
––The objects of study were bitumens of sedimentary rocks and paraffin oils of the Middle Devonian–lower Frasnian terrigenous complex of the Timan–Pechora basin. We studied the composition of biomarker hydrocarbons and the carbon isotope composition of individual n-alkanes of bitumens from the cores of the wells of the Omra–Lyzha saddle. The results were compared with similar data on the composition of paraffin oils from the south of the Pechora–Kozhva megaswell. The generation potential and thermal maturity of organic matter were studied by the Rock-Eval pyrolysis method. The maturity of organic matter in the rocks of the studied complex in the Omra–Lyzha saddle and the Pechora–Kozhva megaswell corresponds to the oil window. Data on the carbon isotopy of n-alkanes and on the composition of biomarker hydrocarbons do not contradict the possible genetic relationship between paraffin oils and the organic matter of the host sedimentary complex. Both the studied paraffin oils and the rock bitumens contain early eluting rearranged hopanes atypical of oils of other petroliferous complexes and show high contents of n-alkanes relative to iso-alkanes and polycyclic biomarkers. The content of 13C tends to decrease with an increase in the number of carbon atoms in the n-alkane molecule in both oils and bitumen rocks.
{"title":"Biomarker Hydrocarbons and Carbon Isotopes of Individual n-Alkanes in Paraffin Oils and Bitumens of the Middle Devonian–Lower Frasnian Terrigenous Complex of the Timan–Pechora Basin","authors":"D. Bushnev, A. Ilchenko, L. V. Ogdanets, N. S. Burdel’naya","doi":"10.2113/rgg20234674","DOIUrl":"https://doi.org/10.2113/rgg20234674","url":null,"abstract":"\u0000 ––The objects of study were bitumens of sedimentary rocks and paraffin oils of the Middle Devonian–lower Frasnian terrigenous complex of the Timan–Pechora basin. We studied the composition of biomarker hydrocarbons and the carbon isotope composition of individual n-alkanes of bitumens from the cores of the wells of the Omra–Lyzha saddle. The results were compared with similar data on the composition of paraffin oils from the south of the Pechora–Kozhva megaswell. The generation potential and thermal maturity of organic matter were studied by the Rock-Eval pyrolysis method. The maturity of organic matter in the rocks of the studied complex in the Omra–Lyzha saddle and the Pechora–Kozhva megaswell corresponds to the oil window. Data on the carbon isotopy of n-alkanes and on the composition of biomarker hydrocarbons do not contradict the possible genetic relationship between paraffin oils and the organic matter of the host sedimentary complex. Both the studied paraffin oils and the rock bitumens contain early eluting rearranged hopanes atypical of oils of other petroliferous complexes and show high contents of n-alkanes relative to iso-alkanes and polycyclic biomarkers. The content of 13C tends to decrease with an increase in the number of carbon atoms in the n-alkane molecule in both oils and bitumen rocks.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"1 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140713224","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}
––We present the results of the study of the effect of induced magnetic polarization of clay beds under the influence of an external harmonic electromagnetic field (frequencies 70 and 875 kHz). A two-stage numerical modeling procedure is proposed. At the first stage we determine the effective relative magnetic permeability of a synthetic sample with inclusions of clay particles. In this case a 3D heterogeneous mesh sample is generated. Then we numerically model a spatial distribution of an electric field. The electromotive force (EMF) induced in the measuring coil is calculated from this distribution. Relative magnetic permeability is determined by comparison with EMF of homogeneous samples with different values of magnetic permeability. It has been found that during the electric field excitation by an alternating current coil, the effect of induced magnetic polarization appears in the sample with clay particles. Its manifestation is that the effective magnetic permeability becomes complex. At the second stage we calculate the EMF diagram of the three-coil logging probe in the macro-model ‘clay cap – reservoir’. Magnetic permeability of the clay cap is given by a complex value. In the generated logs, extremes appear in the vicinity of the bottom of the clay cap; they do not correspond to the distribution of electrical conductivity and magnetic permeability in the given model. They can be incorrectly interpreted when analyzing real logs into individual formations. Numerical modeling at all stages is performed by the Vector Finite Element Method on a consistent adaptive tetrahedral partition and the first-order Webb vector basis.
{"title":"Influence of Magnetic Polarization on Diagrams of Inductive and Electromagnetic Logs","authors":"E.I. Shtanko, D.A. Arkhipov, M. Epov","doi":"10.2113/rgg20234671","DOIUrl":"https://doi.org/10.2113/rgg20234671","url":null,"abstract":"\u0000 ––We present the results of the study of the effect of induced magnetic polarization of clay beds under the influence of an external harmonic electromagnetic field (frequencies 70 and 875 kHz). A two-stage numerical modeling procedure is proposed. At the first stage we determine the effective relative magnetic permeability of a synthetic sample with inclusions of clay particles. In this case a 3D heterogeneous mesh sample is generated. Then we numerically model a spatial distribution of an electric field. The electromotive force (EMF) induced in the measuring coil is calculated from this distribution. Relative magnetic permeability is determined by comparison with EMF of homogeneous samples with different values of magnetic permeability. It has been found that during the electric field excitation by an alternating current coil, the effect of induced magnetic polarization appears in the sample with clay particles. Its manifestation is that the effective magnetic permeability becomes complex. At the second stage we calculate the EMF diagram of the three-coil logging probe in the macro-model ‘clay cap – reservoir’. Magnetic permeability of the clay cap is given by a complex value. In the generated logs, extremes appear in the vicinity of the bottom of the clay cap; they do not correspond to the distribution of electrical conductivity and magnetic permeability in the given model. They can be incorrectly interpreted when analyzing real logs into individual formations. Numerical modeling at all stages is performed by the Vector Finite Element Method on a consistent adaptive tetrahedral partition and the first-order Webb vector basis.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"116 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140724456","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}
––Dinocyst assemblages are subjected to taxonomic typification based on a qualitative and quantitative assessment of their generic composition for the Northern Hemisphere during the Coniacian–Santonian time in order to identify correlation taxa. The typification is carried out using a cluster analysis according to the Jacquard calculation model (BioDiversity Professional, 1997). Three types of dinocyst assemblages have been identified in the Coniacian. As compared to the Turonian, the relatively cold-water West Siberian basin is characterized by a decrease in the number of cosmopolitan taxa and an increase in species endemism. The only taxa identified at present are those allowing for intrabasin correlations. Three types of dinocyst assemblages have also been established for the Santonian. Free interbasin connections in the Northern Hemisphere contribute to the equalization of the generic composition between the three identified types and to the identification of characteristic taxa that allow for interregional correlation.
{"title":"Biogeography and Paleogeography of Taxonomic Diversity of Coniacian–Santonian Dinocysts of the Northern Hemisphere","authors":"N. Lebedeva","doi":"10.2113/rgg20244717","DOIUrl":"https://doi.org/10.2113/rgg20244717","url":null,"abstract":"\u0000 ––Dinocyst assemblages are subjected to taxonomic typification based on a qualitative and quantitative assessment of their generic composition for the Northern Hemisphere during the Coniacian–Santonian time in order to identify correlation taxa. The typification is carried out using a cluster analysis according to the Jacquard calculation model (BioDiversity Professional, 1997). Three types of dinocyst assemblages have been identified in the Coniacian. As compared to the Turonian, the relatively cold-water West Siberian basin is characterized by a decrease in the number of cosmopolitan taxa and an increase in species endemism. The only taxa identified at present are those allowing for intrabasin correlations. Three types of dinocyst assemblages have also been established for the Santonian. Free interbasin connections in the Northern Hemisphere contribute to the equalization of the generic composition between the three identified types and to the identification of characteristic taxa that allow for interregional correlation.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"13 5","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140724649","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}
––The search for oil and gas in folded zones and in the foredeep of the cis-Uralian region for many decades was reduced to testing of easy-to-find closures and reefs located at shallow depths. Many important discoveries were made as a result, but the overall performance of the work remained relatively low. On the one hand, this was due to the poor subsurface imaging of the data for reliable preparation of structures in regions of complex structure. On the other hand, the peculiarities of the development of oil and gas systems in these regions were ignored during the assessment of prospecting sites. In comparison with traditional production hubs centers in the platform regions of the Volga–Ural and Timan–Pechora basins, this distinguishing feature was caused by a thicker sedimentary cover, the variability of its composition and structure, and multiple phases of structural development. Many failures were due to the formation of traps after the passage of the primary migration flow of oil and gas, low capacity of reservoirs, and their fracturing by faults. As shown by interpretation of new geodata using modern knowledge about the oil and gas potential of regions of similar structure, the cis-Uralian region contains poorly studied oil and gas accumulation zones that can contain large deposits. These include blind thrust regions, subsalt traps in development zones of dislocated diapirs, and also stratigraphic and combined traps associated with unconformities and facies changes. The utmost attention is paid to new prospecting objects in the Timan–Pechora basin in which the thickness of the Paleozoic cover has increased. The preparation of new promising objects in these zones has become possible due to new knowledge and better geophysical data.
{"title":"New Oil and Gas Plays in the Cis-Urals","authors":"K.O. Sobornov","doi":"10.2113/rgg20234652","DOIUrl":"https://doi.org/10.2113/rgg20234652","url":null,"abstract":"\u0000 ––The search for oil and gas in folded zones and in the foredeep of the cis-Uralian region for many decades was reduced to testing of easy-to-find closures and reefs located at shallow depths. Many important discoveries were made as a result, but the overall performance of the work remained relatively low. On the one hand, this was due to the poor subsurface imaging of the data for reliable preparation of structures in regions of complex structure. On the other hand, the peculiarities of the development of oil and gas systems in these regions were ignored during the assessment of prospecting sites. In comparison with traditional production hubs centers in the platform regions of the Volga–Ural and Timan–Pechora basins, this distinguishing feature was caused by a thicker sedimentary cover, the variability of its composition and structure, and multiple phases of structural development. Many failures were due to the formation of traps after the passage of the primary migration flow of oil and gas, low capacity of reservoirs, and their fracturing by faults. As shown by interpretation of new geodata using modern knowledge about the oil and gas potential of regions of similar structure, the cis-Uralian region contains poorly studied oil and gas accumulation zones that can contain large deposits. These include blind thrust regions, subsalt traps in development zones of dislocated diapirs, and also stratigraphic and combined traps associated with unconformities and facies changes. The utmost attention is paid to new prospecting objects in the Timan–Pechora basin in which the thickness of the Paleozoic cover has increased. The preparation of new promising objects in these zones has become possible due to new knowledge and better geophysical data.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"7 3","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140721036","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}
V. Simonov, A. Kotlyarov, A.A. Kotov, A. Perepelov, N. Karmanov, A. Borovikov
—The study of minerals, melt inclusions, as well as natural glasses showed that two different melts contributed to the formation of ignimbrites of the Khangar Volcano. The first, providing the information on melt inclusions in plagioclase and quartz phenocrysts, represents the state of magma in a deep source. The other type of melt is responsible for the formation of glasses and microcrystals of feldspars in fiamme. Experimental and analytical studies of melt inclusions showed that crystallization of most plagioclase and quartz phenocrysts from ignimbrites of the Khangar Volcano occurred at temperatures of 840–960 °C and pressures up to 1.1 kbar, from the melt with water contents up to 3.23 wt.%, under the conditions of magma chamber. The presence of syngenetic primary melt and fluid inclusions in plagioclase and quartz phenocrysts from ignimbrites of the Khangar Volcano indicates phase separation (“boiling”) of the melt with mass formation of СО2 microbubbles in magma. The other type of melt is secondary relative to magmatic systems of the Khangar Volcano and is formed by sintering and melting of tuffogenic volcanoclastic material. This melt contributed to the formation of fiamme in the examined ignimbrites. Based on the study of glasses and microcrystals of feldspars in fiamme, it was found that crystallization of oligoclase occurred at temperatures of 770–840 °C in the melt between the spherules (with water content up to 2.91 wt.%). Sanidine crystals grew over spherules at lower temperatures, 680–760 °C.
{"title":"Formation Conditions of Ignimbrites of the Khangar Volcano (Kamchatka)","authors":"V. Simonov, A. Kotlyarov, A.A. Kotov, A. Perepelov, N. Karmanov, A. Borovikov","doi":"10.2113/rgg20234566","DOIUrl":"https://doi.org/10.2113/rgg20234566","url":null,"abstract":"\u0000 —The study of minerals, melt inclusions, as well as natural glasses showed that two different melts contributed to the formation of ignimbrites of the Khangar Volcano. The first, providing the information on melt inclusions in plagioclase and quartz phenocrysts, represents the state of magma in a deep source. The other type of melt is responsible for the formation of glasses and microcrystals of feldspars in fiamme. Experimental and analytical studies of melt inclusions showed that crystallization of most plagioclase and quartz phenocrysts from ignimbrites of the Khangar Volcano occurred at temperatures of 840–960 °C and pressures up to 1.1 kbar, from the melt with water contents up to 3.23 wt.%, under the conditions of magma chamber. The presence of syngenetic primary melt and fluid inclusions in plagioclase and quartz phenocrysts from ignimbrites of the Khangar Volcano indicates phase separation (“boiling”) of the melt with mass formation of СО2 microbubbles in magma. The other type of melt is secondary relative to magmatic systems of the Khangar Volcano and is formed by sintering and melting of tuffogenic volcanoclastic material. This melt contributed to the formation of fiamme in the examined ignimbrites. Based on the study of glasses and microcrystals of feldspars in fiamme, it was found that crystallization of oligoclase occurred at temperatures of 770–840 °C in the melt between the spherules (with water content up to 2.91 wt.%). Sanidine crystals grew over spherules at lower temperatures, 680–760 °C.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":"273 ","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140752509","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}
V. Malov, V. Strakhovenko, D. Subetto, E. Ovdina, M. Potakhin, N. Belkina, G. Malov
––Carbonaceous (shungite) rocks have high contents of trace elements, which can get to the environment through natural weathering. Shungite rocks are a group of Precambrian carbonaceous rocks of volcanic and sedimentary genesis in Karelia. In this work we present results of studying the mineral and geochemical compositions of shungite rocks at their outcrops on the shoreline of Lake Onega. The interaction of the Onega waters with shungite rocks led to: (1) the removal of most elements, except for K, Mn, Ba, and Mg, whose contents in the rocks increased; (2) the formation of an assemblage of secondary minerals, such as hematite, jarosite, goethite, chalcocite, anglesite, brookite, and Mn hydroxides. Based on the results obtained, we propose a model of the transformation of high-carbon (shungite) rocks by the Onega waters.
{"title":"Alterations of High-Carbon (Shungite) Rocks by the Lake Onega Waters: Mineralogy and Geochemistry of the Process","authors":"V. Malov, V. Strakhovenko, D. Subetto, E. Ovdina, M. Potakhin, N. Belkina, G. Malov","doi":"10.2113/rgg20234690","DOIUrl":"https://doi.org/10.2113/rgg20234690","url":null,"abstract":"\u0000 ––Carbonaceous (shungite) rocks have high contents of trace elements, which can get to the environment through natural weathering. Shungite rocks are a group of Precambrian carbonaceous rocks of volcanic and sedimentary genesis in Karelia. In this work we present results of studying the mineral and geochemical compositions of shungite rocks at their outcrops on the shoreline of Lake Onega. The interaction of the Onega waters with shungite rocks led to: (1) the removal of most elements, except for K, Mn, Ba, and Mg, whose contents in the rocks increased; (2) the formation of an assemblage of secondary minerals, such as hematite, jarosite, goethite, chalcocite, anglesite, brookite, and Mn hydroxides. Based on the results obtained, we propose a model of the transformation of high-carbon (shungite) rocks by the Onega waters.","PeriodicalId":506591,"journal":{"name":"Russian Geology and Geophysics","volume":" 27","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-03-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140221616","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}
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