Pub Date : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-870-891
Ekaterina Klimovskaya, A. Ivanov
Object of study. The paper presents the mineralogical and petrographic study results of metamorphosed and metasomatized komatiites and komatiitic peridotites from the Ozerki soapstone deposit and Pentinsuo prospect, located in the Kostomuksha greenstone structure of the Karelian Craton, Fennoscandian Shield. Material and methods. Surface and drill core samples of various mineral and structural-textural varieties of altered komatiites were studied by optical microscopy, electron microscopy with an attachment for microanalysis, XRD phase, thermogravimetric and chemical analysis. Results. Soapstone formation in the investigated localities displays a multistage alteration and associates with the superimposed alteration of Mg-rich metakomatiite flows and olivine cumulates due to influx of carbon dioxide bearing fluids enriched in calcium and potassium. The chemical composition of initial komatiite (MgO content of the rock) and the degree of its fracture intensity are the main factors controlling soapstone formation. In differentiated lava flows soapstone is formed mainly in high-magnesium cumulate zones characterized by a high content of serpentine. In the flow top and spinifex zones an early amphibole-chlorite-magnetite mineral association is preserved in varying degrees. Talc and carbonate are formed by the decomposition of serpentine and amphibole. The chlorite content in soapstone is controlled by the Al2O3 concentration in the respective flow zones. Conclusion. The carbonate-chlorite-talc is the general natural type of soapstone associated with thin komatiite lava flows of distal volcanic facies. In more thick proximal lava flows the formation of soapstone of chloritecarbonate-talc and talc-carbonate composition is possible. The most prefered prospecting areas for soapstone are fields proximal to the eruptive vent, main lava conduits and subvolcanic analogues of komatiites.
{"title":"Mineralogical and petrographic features of metakomatiites of the Kostomuksha greenstone structure (Karelia)","authors":"Ekaterina Klimovskaya, A. Ivanov","doi":"10.24930/1681-9004-2018-18-6-870-891","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-870-891","url":null,"abstract":"Object of study. The paper presents the mineralogical and petrographic study results of metamorphosed and metasomatized komatiites and komatiitic peridotites from the Ozerki soapstone deposit and Pentinsuo prospect, located in the Kostomuksha greenstone structure of the Karelian Craton, Fennoscandian Shield. Material and methods. Surface and drill core samples of various mineral and structural-textural varieties of altered komatiites were studied by optical microscopy, electron microscopy with an attachment for microanalysis, XRD phase, thermogravimetric and chemical analysis. Results. Soapstone formation in the investigated localities displays a multistage alteration and associates with the superimposed alteration of Mg-rich metakomatiite flows and olivine cumulates due to influx of carbon dioxide bearing fluids enriched in calcium and potassium. The chemical composition of initial komatiite (MgO content of the rock) and the degree of its fracture intensity are the main factors controlling soapstone formation. In differentiated lava flows soapstone is formed mainly in high-magnesium cumulate zones characterized by a high content of serpentine. In the flow top and spinifex zones an early amphibole-chlorite-magnetite mineral association is preserved in varying degrees. Talc and carbonate are formed by the decomposition of serpentine and amphibole. The chlorite content in soapstone is controlled by the Al2O3 concentration in the respective flow zones. Conclusion. The carbonate-chlorite-talc is the general natural type of soapstone associated with thin komatiite lava flows of distal volcanic facies. In more thick proximal lava flows the formation of soapstone of chloritecarbonate-talc and talc-carbonate composition is possible. The most prefered prospecting areas for soapstone are fields proximal to the eruptive vent, main lava conduits and subvolcanic analogues of komatiites.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"42 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90945179","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}
Pub Date : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-779-796
V. A. Koroteev, V. M. Necheukhin, A. A. Krasnobaev, E. N. Volchek
Subject of study. Different points of view on the concept of structures of the terrain type and their role in the addition of orogenic belts are considered. Materials and methods. We used our own research and analysis of the latest publications about the Ural-Timan region and the Pacific belt, on the territory of the Northeast segment of Eurasia, as well as currently known isotope radiometric data. It was used also the result of geophysical seismotectonic and paleomagnetic explorations. Results. It has been established that in the composition of the Ural-Timan structural area, along with the Proterozoic and Paleozoic associations of the orogenic belts and the Riphean sedimentary series of protrusions of the Russian Plate, structural formations that correspond to the terrain of the continental crust take part. They are the most characteristic for the Ural orogenic belt, which belongs to the group of epiokean-type belts, associated with the transformation of ocean basins with the active participation of accretion and collision processes. The parametric features of these terrains include the ancient age characteristics of terrain rocks, their position in the belt structure, as well as the presence of relics of subhorizontal layered structural elements. The discordant blocks of migmatites, gneisses and other metamorphic rocks of Precambrian age, which make up the terrains, was the basis for the introduction of the term “terranes of the ancient continental crust”. By connection with the source, exotic and endemic, and simple and complex terrains are distinguished by structure. The geodynamics of including terrains of the ancient continental crust into the structure of orogenic belts is associated with horizontal movements of fragments of the ancient lithosphere in oceanic paleobasins to the periphery of the Russian Plate and their localization in belt structures. The formation of these terrains in the structures of the orogenic belts is completed by the formation of the intra-terrain massifs of granitoids and belts of volcanic-intrusive series. Supporters of a different methodology, dominant among researchers of the Pacific Belt of the Northeast Segment of Eurasia, refer to terrains all the structural elements that perform orogenic belts, because they believe that they have undergone horizontal movements and are in allochtonous occurrence. Conclusions. It has been established that in different geological provinces the term terrain has its own characteristics. This was the basis for the selection of two geodynamic types of terrains.
{"title":"Terrains of the main geodynamical types in the structures of Ural-Timan areal and the Eurasia North-Eastern segment","authors":"V. A. Koroteev, V. M. Necheukhin, A. A. Krasnobaev, E. N. Volchek","doi":"10.24930/1681-9004-2018-18-6-779-796","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-779-796","url":null,"abstract":"Subject of study. Different points of view on the concept of structures of the terrain type and their role in the addition of orogenic belts are considered. Materials and methods. We used our own research and analysis of the latest publications about the Ural-Timan region and the Pacific belt, on the territory of the Northeast segment of Eurasia, as well as currently known isotope radiometric data. It was used also the result of geophysical seismotectonic and paleomagnetic explorations. Results. It has been established that in the composition of the Ural-Timan structural area, along with the Proterozoic and Paleozoic associations of the orogenic belts and the Riphean sedimentary series of protrusions of the Russian Plate, structural formations that correspond to the terrain of the continental crust take part. They are the most characteristic for the Ural orogenic belt, which belongs to the group of epiokean-type belts, associated with the transformation of ocean basins with the active participation of accretion and collision processes. The parametric features of these terrains include the ancient age characteristics of terrain rocks, their position in the belt structure, as well as the presence of relics of subhorizontal layered structural elements. The discordant blocks of migmatites, gneisses and other metamorphic rocks of Precambrian age, which make up the terrains, was the basis for the introduction of the term “terranes of the ancient continental crust”. By connection with the source, exotic and endemic, and simple and complex terrains are distinguished by structure. The geodynamics of including terrains of the ancient continental crust into the structure of orogenic belts is associated with horizontal movements of fragments of the ancient lithosphere in oceanic paleobasins to the periphery of the Russian Plate and their localization in belt structures. The formation of these terrains in the structures of the orogenic belts is completed by the formation of the intra-terrain massifs of granitoids and belts of volcanic-intrusive series. Supporters of a different methodology, dominant among researchers of the Pacific Belt of the Northeast Segment of Eurasia, refer to terrains all the structural elements that perform orogenic belts, because they believe that they have undergone horizontal movements and are in allochtonous occurrence. Conclusions. It has been established that in different geological provinces the term terrain has its own characteristics. This was the basis for the selection of two geodynamic types of terrains.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"72895985","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}
Pub Date : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-914-927
A. Maslennikova, V. Udachin, V. Deryagin, M. Shtenberg
Object. Multi-proxy analysis of 265 cm long sediments core of Lake Turgoyak, one of the deepest lakes of the Southern Urals, is presented. Materials and methods. The lake ecosystem changes was reconstructed based on diatom, radiocarbon dating and geochemical analysis. Statistical treatment of the surface sediments composition and hydrochemistry data of 56 lakes from Southern and Middle Urals lakes database allowed to obtain geochemical indexes for reconstruction of water parameters: index of organic matter content (ОМ = LOI550ºС/(Al2O3 + TiO2 + Na2O + K2O)) and index of salinity (ММ = LOI950ºC/LOI550ºС). Results. Radiocarbon dating shows that sedimentation in Lake Turgoyak was began more than 12 cal kyr BP ago. Each of six lithological units of sediments core is characterized by its own geochemical features and associated with global (11.8, 11.2, 8.2 cal kyr BP) and regional (12, 10.3 cal kyr BP) climate events of the Northern Hemisphere. Four main stages of Lake ecosystem development were identified: 1) the beginning of lake sedimentation (>12.1 cal kyr BP); 2) the stage of a subsaline shallow-water lake (12.1–11.2 cal kyr BP); 3) the stage of a freshwater lake with increased water-level (11.2–8.0 cal kyr BP); 4) the stage of water organic matter increase (<8.0 cal kyr BP). Conclusions. High content of mesohalobic diatoms and salinity module values showed significant increase of lake water salinity as response to Early Holocene climate warming (11.8–11.2 cal kyr BP). Pantle-Buck’s Saprobity Index and OM values pointed to the lake water organic matter increase due to the next climate warming since 9–8 cal kyr BP. Thus, Lake Turgoyak water parameters were reapeatedly changed during the Holocene. However the response of lake ecosystem was different in different periods of its development.
对象。对乌拉尔南部最深的湖泊之一图尔戈亚克湖265 cm长的沉积物岩心进行了多指标分析。材料和方法。基于硅藻、放射性碳定年和地球化学分析重建了湖泊生态系统的变化。对乌拉尔中南部56个湖泊的表层沉积物组成和水化学数据进行统计处理，得到水体参数重建的地球化学指标:有机质含量指数(ОМ = LOI550ºС/(Al2O3 + TiO2 + Na2O + K2O))和盐度指数(ММ = LOI950ºC/LOI550ºС)。结果。放射性碳测年法显示，图尔戈亚克湖的沉积开始于12亿年前。沉积物岩芯的6个岩性单元均具有各自的地球化学特征，并与北半球全球(11.8、11.2、8.2 cal kyr BP)和区域(12、10.3 cal kyr BP)气候事件相关。确定了湖泊生态系统发育的四个主要阶段:1)湖泊沉积初期(> - 12.1 calkyr BP);2)盐下浅水湖阶段(12.1-11.2 cal kyr BP);3)淡水湖水位上升阶段(11.2 ~ 8.0 cal kyr BP);4)水体有机质增加阶段(<8.0 cal kyr BP)。结论。中藻硅藻的高含量和盐度模块值表明，早全新世(11.8-11.2 cal kyr BP)气候变暖对湖水盐度的响应显著增加。Pantle-Buck’s Saprobity指数和OM值表明，自9-8 cal - kyr BP以来，由于下一次气候变暖，湖泊水体有机质增加。因此，全新世以来，图尔戈雅克湖的水参数发生了反复变化。然而，湖泊生态系统在不同发展时期的响应是不同的。
{"title":"Reconstruction of Turgoyak lake (the Southern Urals) ecosystem changes in holocene","authors":"A. Maslennikova, V. Udachin, V. Deryagin, M. Shtenberg","doi":"10.24930/1681-9004-2018-18-6-914-927","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-914-927","url":null,"abstract":"Object. Multi-proxy analysis of 265 cm long sediments core of Lake Turgoyak, one of the deepest lakes of the Southern Urals, is presented. Materials and methods. The lake ecosystem changes was reconstructed based on diatom, radiocarbon dating and geochemical analysis. Statistical treatment of the surface sediments composition and hydrochemistry data of 56 lakes from Southern and Middle Urals lakes database allowed to obtain geochemical indexes for reconstruction of water parameters: index of organic matter content (ОМ = LOI550ºС/(Al2O3 + TiO2 + Na2O + K2O)) and index of salinity (ММ = LOI950ºC/LOI550ºС). Results. Radiocarbon dating shows that sedimentation in Lake Turgoyak was began more than 12 cal kyr BP ago. Each of six lithological units of sediments core is characterized by its own geochemical features and associated with global (11.8, 11.2, 8.2 cal kyr BP) and regional (12, 10.3 cal kyr BP) climate events of the Northern Hemisphere. Four main stages of Lake ecosystem development were identified: 1) the beginning of lake sedimentation (>12.1 cal kyr BP); 2) the stage of a subsaline shallow-water lake (12.1–11.2 cal kyr BP); 3) the stage of a freshwater lake with increased water-level (11.2–8.0 cal kyr BP); 4) the stage of water organic matter increase (<8.0 cal kyr BP). Conclusions. High content of mesohalobic diatoms and salinity module values showed significant increase of lake water salinity as response to Early Holocene climate warming (11.8–11.2 cal kyr BP). Pantle-Buck’s Saprobity Index and OM values pointed to the lake water organic matter increase due to the next climate warming since 9–8 cal kyr BP. Thus, Lake Turgoyak water parameters were reapeatedly changed during the Holocene. However the response of lake ecosystem was different in different periods of its development.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86884529","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}
Pub Date : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-892-913
V. Kazachenko, E. V. Perevoznikova
Subject.The paper is devoted to the study of the gold-silver-palladium-platinum mineralization of the streaky systems in the sedimentary rocks associated within the Triassic carbonaceous silicites of the Taukhinsky and Samarkinsky terranes of the Sikhote-Alin.Materials and methods.In the process of investigations we studied the metamorphosed carbonaceous siliceous-clay rocks and systems of the mineralized fractures in the Triassic siliceous-clay and siliceous (including jaspers) rocks of Shirokopadninskaya, Vysokogorskaya and Gornaya areas, as well as in the sandstones (unclarified age) of Gornaya area. The samples for the analytical study were taken with the lump way. To estimate the content of precious metals in the rocks, cut by the systems of the mineralized fractures, we used the fire assay and atomic-absorption methods. The analyses of minerals (in polished sections) have been done using the JXA-5A and JXA8100 microanalysers.Results.The gold-silver-palladium-platinum mineralization in the siliceous and clay-siliceous rocks, as well as in the sandstones is restricted to the systems of the mineralized fractures and by many features are analogous to the precious-metal mineralization of the black-shale formations. It is represented by native forms, disordered solid solutions, and intermetallic compounds of different metals. The specificity of the Au-Ag-Pd-Pt mineralization is a wide distribution of copper gold, Ni-, Cu-, and Pbbearing gold, and Zn-bearing platinum. Native elements and intermetallic compounds, including those of precious metals, are not rarely associated with the organic matter testifying to the active participation of carbon and, probably, hydrogen that provided the high- and ultra-reduction character of the processes of mineral formation.Conclusions.The presence of the mineral forms of different maximum reduced metals is caused by the influence of the organic matter of the Triassic carbonaceous silicites. This consisted in the removal of the most volatile components, and first of all the poorly bound water and hydrocarbons from the carbonaceous rocks through the contact metamorphism related with the injection of the granitoid intrusions of Cretaceous plutonic and volcanoplutonic belts.
{"title":"Au-Ag-Pd-Pt mineralization in sedimentary rocks associated with Triassic carbonaceous silicites of Sikhote-Alin","authors":"V. Kazachenko, E. V. Perevoznikova","doi":"10.24930/1681-9004-2018-18-6-892-913","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-892-913","url":null,"abstract":"Subject.The paper is devoted to the study of the gold-silver-palladium-platinum mineralization of the streaky systems in the sedimentary rocks associated within the Triassic carbonaceous silicites of the Taukhinsky and Samarkinsky terranes of the Sikhote-Alin.Materials and methods.In the process of investigations we studied the metamorphosed carbonaceous siliceous-clay rocks and systems of the mineralized fractures in the Triassic siliceous-clay and siliceous (including jaspers) rocks of Shirokopadninskaya, Vysokogorskaya and Gornaya areas, as well as in the sandstones (unclarified age) of Gornaya area. The samples for the analytical study were taken with the lump way. To estimate the content of precious metals in the rocks, cut by the systems of the mineralized fractures, we used the fire assay and atomic-absorption methods. The analyses of minerals (in polished sections) have been done using the JXA-5A and JXA8100 microanalysers.Results.The gold-silver-palladium-platinum mineralization in the siliceous and clay-siliceous rocks, as well as in the sandstones is restricted to the systems of the mineralized fractures and by many features are analogous to the precious-metal mineralization of the black-shale formations. It is represented by native forms, disordered solid solutions, and intermetallic compounds of different metals. The specificity of the Au-Ag-Pd-Pt mineralization is a wide distribution of copper gold, Ni-, Cu-, and Pbbearing gold, and Zn-bearing platinum. Native elements and intermetallic compounds, including those of precious metals, are not rarely associated with the organic matter testifying to the active participation of carbon and, probably, hydrogen that provided the high- and ultra-reduction character of the processes of mineral formation.Conclusions.The presence of the mineral forms of different maximum reduced metals is caused by the influence of the organic matter of the Triassic carbonaceous silicites. This consisted in the removal of the most volatile components, and first of all the poorly bound water and hydrocarbons from the carbonaceous rocks through the contact metamorphism related with the injection of the granitoid intrusions of Cretaceous plutonic and volcanoplutonic belts.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82503700","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}
Pub Date : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-928-941
L. Kondratyeva, O. S. Polevskaya, E. Golubeva, A. V. Shtareva, N. Konovalova
Object of research.The aim of this work was the comparative analysis of element composition of groundwater (drip, fracture), water from the interior of the watercourse in a karst cave Proshchal’naya (Khabarovsk Territory) and the surface water of the nearest river Sagdy-Selanka. The great interest was the study of speleothem (dropstones) “moon milk” in the cave Proshchal’naya.Materials and methods.Speleothem “moon milk” was investigated with a scanning electron microscope (EVO-40HV, CarlZeiss, Germany) and silicon-drift x-ray detector X-MAX 80 мм2 . By ICP-MS method a comparative analysis of element composition of groundwater (drip, fracture), water from an internal stream in the cave Proshchal’naya and surface water of the river Sagdy-Selenka were carried out.Results.Maximum concentrations of calcium, iron and manganese was installed in the spring, between drip and fracture water and magnesium – in flowing waters (inland watercourse caves and Sagdy-Selanka R.). It was determined that visually plastic and homogeneous mass of speleothem “moon milk” is heterogeneous and contains various microstructures. Tubular microstructures were represented by richer elemental compo sition (C, O, Ca, Fe, Mn, Si, Al, and S) compared with club-shaped formations (C, O, Ca, and Na). The binding matrix in the composition of the “moon milk” were reticular structures similar to actinomycente mycelium and bacterial films. Findings. The results of studies conducted in a monsoon climate may be interesting for researchers which study karst processes in other climatic zones.
{"title":"Element composition of ground water and speleothem “moon milkˮ in a karst cave Proshchal’naya (Far East)","authors":"L. Kondratyeva, O. S. Polevskaya, E. Golubeva, A. V. Shtareva, N. Konovalova","doi":"10.24930/1681-9004-2018-18-6-928-941","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-928-941","url":null,"abstract":"Object of research.The aim of this work was the comparative analysis of element composition of groundwater (drip, fracture), water from the interior of the watercourse in a karst cave Proshchal’naya (Khabarovsk Territory) and the surface water of the nearest river Sagdy-Selanka. The great interest was the study of speleothem (dropstones) “moon milk” in the cave Proshchal’naya.Materials and methods.Speleothem “moon milk” was investigated with a scanning electron microscope (EVO-40HV, CarlZeiss, Germany) and silicon-drift x-ray detector X-MAX 80 мм2 . By ICP-MS method a comparative analysis of element composition of groundwater (drip, fracture), water from an internal stream in the cave Proshchal’naya and surface water of the river Sagdy-Selenka were carried out.Results.Maximum concentrations of calcium, iron and manganese was installed in the spring, between drip and fracture water and magnesium – in flowing waters (inland watercourse caves and Sagdy-Selanka R.). It was determined that visually plastic and homogeneous mass of speleothem “moon milk” is heterogeneous and contains various microstructures. Tubular microstructures were represented by richer elemental compo sition (C, O, Ca, Fe, Mn, Si, Al, and S) compared with club-shaped formations (C, O, Ca, and Na). The binding matrix in the composition of the “moon milk” were reticular structures similar to actinomycente mycelium and bacterial films. Findings. The results of studies conducted in a monsoon climate may be interesting for researchers which study karst processes in other climatic zones.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"72 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86287517","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}
Pub Date : 2018-12-28DOI: 10.24930/1681-9004-2018-18-6-797-818
M. Dubrovsky
The object of research. The main goal of the work was to resolve the problem of the existence of rock associations: alkaline granites–syenites–nepheline syenites, which is found on all continents among ancient platforms and stabilized folded regions of different ages. Beginning with 70-th. of the past century, the absolute majority of the world's petrologists do not allow the possibility of a comagmatic formation of such a rock association due to the presence of a thermal albite “barrier” between phonolitic and rhyolitic melts. Materials and methods. Numerous data were used on the Ilimaussak alkaline massif from southern Greenland as the most thoroughly studied and widely known to petrologists around the world. The main methods of research were the development of physicochemical models of phase transitions and the construction of state diagrams. Results. Earlier, thanks to the author's work in the field of constructing state diagrams, the possibility of “destruction of thermal barriers” was demonstrated at the appearance of alumosilicate melts of biotite, amphibole, analcime and other minerals on the liquidus. The developed physicochemical models of phase transitions for specific rock associations of the Ilimaussak massif allowed us to prove the possibility of a comagmatic transition from nepheline-modal syenites to quartz-modal alkaline granites. Conclusions. The validity (correctness) of the theoretical constructs is proved by an almost perfect coincidence of the model and natural trends of the rock associations. This requires a certain composition of the initial melt and the optimal fluid pressure.
{"title":"Albite thermal barrier and alkaline granite-syenitenepheline-syenite rock association (series, formation, assemblage)","authors":"M. Dubrovsky","doi":"10.24930/1681-9004-2018-18-6-797-818","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-6-797-818","url":null,"abstract":"The object of research. The main goal of the work was to resolve the problem of the existence of rock associations: alkaline granites–syenites–nepheline syenites, which is found on all continents among ancient platforms and stabilized folded regions of different ages. Beginning with 70-th. of the past century, the absolute majority of the world's petrologists do not allow the possibility of a comagmatic formation of such a rock association due to the presence of a thermal albite “barrier” between phonolitic and rhyolitic melts. Materials and methods. Numerous data were used on the Ilimaussak alkaline massif from southern Greenland as the most thoroughly studied and widely known to petrologists around the world. The main methods of research were the development of physicochemical models of phase transitions and the construction of state diagrams. Results. Earlier, thanks to the author's work in the field of constructing state diagrams, the possibility of “destruction of thermal barriers” was demonstrated at the appearance of alumosilicate melts of biotite, amphibole, analcime and other minerals on the liquidus. The developed physicochemical models of phase transitions for specific rock associations of the Ilimaussak massif allowed us to prove the possibility of a comagmatic transition from nepheline-modal syenites to quartz-modal alkaline granites. Conclusions. The validity (correctness) of the theoretical constructs is proved by an almost perfect coincidence of the model and natural trends of the rock associations. This requires a certain composition of the initial melt and the optimal fluid pressure.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"30 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84183401","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}
Pub Date : 2018-10-28DOI: 10.24930/1681-9004-2018-18-5-692-705
V. Puchkov
The plume-dependent magmatism is widespread and well justified. The bulk of it is represented by flood basalts, basalts of oceanic islands (OIB), and basalts of oceanic plateaus (OPB), though the whole scope of plume magmatism is very diverse. A noticeable role among them is played also by acid (silicic) magmatic rocks - rhyolites and granites. Two main types of plume magmatism are recognized. The first belongs to Large Igneous Provinces (LIP) and is thought to be born at the Core-Mantle boundary within structures, called superswells, that produce giant, short-living mantle upwellings, resulting in abundant volcanism on the Earth’s surface. The second type is represented by linear volcanic chains characterized by regular age progressions. They are formed by single plumes - thin ascending mantle flows, acting during longer periods of time. It is shown that the abundance of silicic magmatism strongly depends on the type of the earth’s crust. Among flood basalts of continents, silicic magmatism is usually present, subordinate in volume to basalts and belongs to a bimodal type of magmatism. But in some cases LIP in continents are formed predominantly by silicic rocks; they are given the name Silicic LIPS, or SLIPS. In oceans, LIP are fundamentally basaltic with no considerable volume of silicic volcanics, if any. The time-progressive volcanic chains in continents are rare and usually comprise a noticeable silicic component. In oceans, the chains are composed mostly of basalts (OIB type), though in the top parts of volcanoes more acid and alkaline differentiates are present; usually they lack rhyolites and granites, except the cases of a presence of some strips of continental crust or anomalously thick oceanic crust. This review can lead to a thought of an important role of melting of continental crust in formation of plume-dependent rhyolite-granite magmatism. As for the Urals, the proofs for a presence of plume-dependent magmatism in its history were presented only recently. Among the plume episodes, some are characterized by presence of silicic components, in particular: Mashak (1380-1385 Ma), Igonino (707-732 Ma), Man’khambo (mainly Cambrian), Ordovician Kidryasovo, Stepninsky (Permian) and Urals-Siberian (Triassic).
{"title":"The plume-dependent granite-rhyolite magmatism","authors":"V. Puchkov","doi":"10.24930/1681-9004-2018-18-5-692-705","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-5-692-705","url":null,"abstract":"The plume-dependent magmatism is widespread and well justified. The bulk of it is represented by flood basalts, basalts of oceanic islands (OIB), and basalts of oceanic plateaus (OPB), though the whole scope of plume magmatism is very diverse. A noticeable role among them is played also by acid (silicic) magmatic rocks - rhyolites and granites. Two main types of plume magmatism are recognized. The first belongs to Large Igneous Provinces (LIP) and is thought to be born at the Core-Mantle boundary within structures, called superswells, that produce giant, short-living mantle upwellings, resulting in abundant volcanism on the Earth’s surface. The second type is represented by linear volcanic chains characterized by regular age progressions. They are formed by single plumes - thin ascending mantle flows, acting during longer periods of time. It is shown that the abundance of silicic magmatism strongly depends on the type of the earth’s crust. Among flood basalts of continents, silicic magmatism is usually present, subordinate in volume to basalts and belongs to a bimodal type of magmatism. But in some cases LIP in continents are formed predominantly by silicic rocks; they are given the name Silicic LIPS, or SLIPS. In oceans, LIP are fundamentally basaltic with no considerable volume of silicic volcanics, if any. The time-progressive volcanic chains in continents are rare and usually comprise a noticeable silicic component. In oceans, the chains are composed mostly of basalts (OIB type), though in the top parts of volcanoes more acid and alkaline differentiates are present; usually they lack rhyolites and granites, except the cases of a presence of some strips of continental crust or anomalously thick oceanic crust. This review can lead to a thought of an important role of melting of continental crust in formation of plume-dependent rhyolite-granite magmatism. As for the Urals, the proofs for a presence of plume-dependent magmatism in its history were presented only recently. Among the plume episodes, some are characterized by presence of silicic components, in particular: Mashak (1380-1385 Ma), Igonino (707-732 Ma), Man’khambo (mainly Cambrian), Ordovician Kidryasovo, Stepninsky (Permian) and Urals-Siberian (Triassic).","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"159 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87303977","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}
Pub Date : 2018-10-28DOI: 10.24930/1681-9004-2018-18-5-653-671
M. Kuzmin, V. Yarmolyuk, A. Kotov
The Earth has a number of differences from the planets of the Solar System and other star-planetary systems. These differences were acquired during its formation and geological history. In the early Chaotic eon occurred the accretion of the Earth, the separation of the primary substance of the Earth into a mantle and a nucleus, a satellite of the Earth - the Moon appeared. 4500 Ma ago in the Gadey aeon the geological history of the Earth began. At this time, the endogenous processes on the Earth were controlled to a great extent by meteorite-asteroid bombardments, which caused large-scale melting and differentiation of the upper shells of the Earth. In the magmatic chambers differentiation proceeded until the appearance of melts of granitoid composition. The continental crust of Gadey time was almost completely destroyed by meteoric bombardments, the last heavy bombardment occurred at the end of the Gadey aeon 4000-3900 Ma ago. The geological situation of the Gadey time can be judged only from the preserved zircons from the rocks of that epoch. In particular, their geochemical features indicate that the Earth has an atmosphere. The Gadey eon was replaced by the Archean one, from which the processes of self-organization began to predominate on the Earth. At this time, a crust composed of komatiite-basalt and tonalite-trondhjemite-granodiorite (TTG) series of rocks was formed. In its formation, the processes of sagduction (vertical growth of the crust) over the rising mantle plumes was played the leading role. At the same time the lower basaltic crust was bured in the mantle, eclogitized and melted, which led to the appearance of the sodium series of TTG rocks. At the end of the Archean 3.1-3.0 Ga tectonics of the cover (LID tectonics), which determined the style of the structure and development of the Archean crust, is replaced by the tectonics of small plates, which was later replaced by modern tectonics - the tectonics of plates combined with mantle plumes.
{"title":"The early evolution of the earth, the beginning of its geological history: how and when the granitoid magmas appeared","authors":"M. Kuzmin, V. Yarmolyuk, A. Kotov","doi":"10.24930/1681-9004-2018-18-5-653-671","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-5-653-671","url":null,"abstract":"The Earth has a number of differences from the planets of the Solar System and other star-planetary systems. These differences were acquired during its formation and geological history. In the early Chaotic eon occurred the accretion of the Earth, the separation of the primary substance of the Earth into a mantle and a nucleus, a satellite of the Earth - the Moon appeared. 4500 Ma ago in the Gadey aeon the geological history of the Earth began. At this time, the endogenous processes on the Earth were controlled to a great extent by meteorite-asteroid bombardments, which caused large-scale melting and differentiation of the upper shells of the Earth. In the magmatic chambers differentiation proceeded until the appearance of melts of granitoid composition. The continental crust of Gadey time was almost completely destroyed by meteoric bombardments, the last heavy bombardment occurred at the end of the Gadey aeon 4000-3900 Ma ago. The geological situation of the Gadey time can be judged only from the preserved zircons from the rocks of that epoch. In particular, their geochemical features indicate that the Earth has an atmosphere. The Gadey eon was replaced by the Archean one, from which the processes of self-organization began to predominate on the Earth. At this time, a crust composed of komatiite-basalt and tonalite-trondhjemite-granodiorite (TTG) series of rocks was formed. In its formation, the processes of sagduction (vertical growth of the crust) over the rising mantle plumes was played the leading role. At the same time the lower basaltic crust was bured in the mantle, eclogitized and melted, which led to the appearance of the sodium series of TTG rocks. At the end of the Archean 3.1-3.0 Ga tectonics of the cover (LID tectonics), which determined the style of the structure and development of the Archean crust, is replaced by the tectonics of small plates, which was later replaced by modern tectonics - the tectonics of plates combined with mantle plumes.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"11 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73192636","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}
Pub Date : 2018-10-28DOI: 10.24930/1681-9004-2018-18-5-758-773
I. Nedosekova, V. A. Koroteev, B. Belyatsky, V. Sharygin, Е. N. Lepechinа, S. V. Pribavkin
{"title":"U-pb dating of niobium minerals from pyrochlor group (ilmeno-vishnevogorsk carbonatitis-miaskite complex, of the southern urals)","authors":"I. Nedosekova, V. A. Koroteev, B. Belyatsky, V. Sharygin, Е. N. Lepechinа, S. V. Pribavkin","doi":"10.24930/1681-9004-2018-18-5-758-773","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-5-758-773","url":null,"abstract":"","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"48 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87430076","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}
Pub Date : 2018-10-28DOI: 10.24930/1681-9004-2018-18-5-718-742
Z. Yudalevich, Y. Vapnik
Объектом предлагаемого исследования являются ксенокристы и мегаксенокристы в породах раннемеловой оливин-базальт-базанит-нефелинитовой ассоциации эрозионной котловины махтеш рамон (Негев, израиль). В ней широко развиты ксенолиты разной степени глубинности: мантийные, нижнеи верхнекоровые. ксенолиты мантии представлены перидотитами, оливиновыми клинопироксенитами и клинопироксенитами, оливиновыми вебстеритами, вебстеритами и их амфибол-содержащими разностями; ксенолиты нижней коры – мафическими гранулитами (метагабброиды и плагиоклазиты), верхней коры – позднепротерозойскими метатуфами. ксенокристы и мегакристы являются отщепленными фрагментами ксенолитов. их общей петрографической особенностью является проработка вмещающим расплавом и связанные с ней геохимические и структурные преобразования. В основном ксенокристы представлены когерентным рядом минералов (оливин, клинопироксен, амфибол, нефелин, плагиоклаз, анортоклаз, апатит, магнетит, шпинель) и только ксенокристы кварца и ортопироксена не совместимы с недосыщенными SiO2 вмещающими породами. Главными причинами, инициирующими взаимодействие магматический расплав–ксенокрист, являются быстрая декомпрессия, метаморфизм и метасоматоз. метаморфизм соответствует высокотемпературным фациям контактового метаморфизма, иногда достигая стадии плавления. Mетасоматоз ориентирован на выравнивание составов с одноименными минералами вмещающего расплава. к числу важнейших критериев, способствующих отличию ксенокристов от фенокристов, относятся частичное плавление, твердофазный распад, рекристаллизация первичных (дозахватных) структур, перекристаллизация и само огранка изначально ксеноморфных зерен в кристаллографически правильные формы, бимодальность состава, совмещающего минералого-геохимические признаки ксеногенного и новообразованного вещества.
{"title":"Xenocrysts and megacrysts of alkali olivine-basalt-basanite-nephelinite association makhtesh ramon (israel): interaction with transporting magmas and morphological adjustment","authors":"Z. Yudalevich, Y. Vapnik","doi":"10.24930/1681-9004-2018-18-5-718-742","DOIUrl":"https://doi.org/10.24930/1681-9004-2018-18-5-718-742","url":null,"abstract":"Объектом предлагаемого исследования являются ксенокристы и мегаксенокристы в породах раннемеловой оливин-базальт-базанит-нефелинитовой ассоциации эрозионной котловины махтеш рамон (Негев, израиль). В ней широко развиты ксенолиты разной степени глубинности: мантийные, нижнеи верхнекоровые. ксенолиты мантии представлены перидотитами, оливиновыми клинопироксенитами и клинопироксенитами, оливиновыми вебстеритами, вебстеритами и их амфибол-содержащими разностями; ксенолиты нижней коры – мафическими гранулитами (метагабброиды и плагиоклазиты), верхней коры – позднепротерозойскими метатуфами. ксенокристы и мегакристы являются отщепленными фрагментами ксенолитов. их общей петрографической особенностью является проработка вмещающим расплавом и связанные с ней геохимические и структурные преобразования. В основном ксенокристы представлены когерентным рядом минералов (оливин, клинопироксен, амфибол, нефелин, плагиоклаз, анортоклаз, апатит, магнетит, шпинель) и только ксенокристы кварца и ортопироксена не совместимы с недосыщенными SiO2 вмещающими породами. Главными причинами, инициирующими взаимодействие магматический расплав–ксенокрист, являются быстрая декомпрессия, метаморфизм и метасоматоз. метаморфизм соответствует высокотемпературным фациям контактового метаморфизма, иногда достигая стадии плавления. Mетасоматоз ориентирован на выравнивание составов с одноименными минералами вмещающего расплава. к числу важнейших критериев, способствующих отличию ксенокристов от фенокристов, относятся частичное плавление, твердофазный распад, рекристаллизация первичных (дозахватных) структур, перекристаллизация и само огранка изначально ксеноморфных зерен в кристаллографически правильные формы, бимодальность состава, совмещающего минералого-геохимические признаки ксеногенного и новообразованного вещества.","PeriodicalId":32819,"journal":{"name":"Litosfera","volume":"22 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2018-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84817648","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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