Pub Date : 2020-09-23DOI: 10.5800/gt-2020-11-3-0494
T. Artikov, R. Ibragimov, T. L. Ibragimova, M. Mirzaev
Seismic intensity assessment in points of a macroseismic scale plays an important role for researching the seismic history of areas characterized by active seismicity, as well as for construction (and updating) of seismic zoning maps in various scales. Macroseismic scale points are generally referred to in construction standards applied in the majority of post-Soviet states. In our study aimed to model the macroseismic field of earthquakes, a large volume of macroseismic data on Central Asia was analyzed, and coefficients used in Blake–Shebalin and Covesligeti equations were aligned. This article presents a generalized dependence model of macroseismic intensity attenuation with distance. The model takes into account seismic load features determined by various depths of earthquakes. The ratios of small and big axes of the ellipse, that approximates real isoseists, are estimated with respect to seismic scale points, earthquake depths and magnitudes. The East Uzbekistan area is studied as an example to investigate whether seismic hazard assessment values may differ depending on a chosen law of seismic influence intensity attenuation with distance.
{"title":"Models of the macroseismic field earthquakes and their influence on seismic hazard assessment values for Central Asia","authors":"T. Artikov, R. Ibragimov, T. L. Ibragimova, M. Mirzaev","doi":"10.5800/gt-2020-11-3-0494","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0494","url":null,"abstract":"Seismic intensity assessment in points of a macroseismic scale plays an important role for researching the seismic history of areas characterized by active seismicity, as well as for construction (and updating) of seismic zoning maps in various scales. Macroseismic scale points are generally referred to in construction standards applied in the majority of post-Soviet states. In our study aimed to model the macroseismic field of earthquakes, a large volume of macroseismic data on Central Asia was analyzed, and coefficients used in Blake–Shebalin and Covesligeti equations were aligned. This article presents a generalized dependence model of macroseismic intensity attenuation with distance. The model takes into account seismic load features determined by various depths of earthquakes. The ratios of small and big axes of the ellipse, that approximates real isoseists, are estimated with respect to seismic scale points, earthquake depths and magnitudes. The East Uzbekistan area is studied as an example to investigate whether seismic hazard assessment values may differ depending on a chosen law of seismic influence intensity attenuation with distance.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"117 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80001125","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0485
V. S. Fedorovsky, E. Sklyarov, D. Gladkochub, A. Mazukabzov, T. Donskaya, A. V. Lavrenchuk, A. Starikova, N. Dobretsov, A. Kotov, A. V. Tevelev
{"title":"Collision system of West Pribaikalie: aerospace geological map of Olkhon Region (Baikal, Russia)","authors":"V. S. Fedorovsky, E. Sklyarov, D. Gladkochub, A. Mazukabzov, T. Donskaya, A. V. Lavrenchuk, A. Starikova, N. Dobretsov, A. Kotov, A. V. Tevelev","doi":"10.5800/gt-2020-11-3-0485","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0485","url":null,"abstract":"","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"60 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85875969","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0497
E. Dutova, V. Kats, A. Shitov, A. Surnin, V. Molokov
. This study of groundwaters of the Altai Republic is relevant due to the need to identify earthquake precursors in seismically active zones of the study area. Chemical composition of groundwater is widely known as an indicator of seismic processes, which changes in future earthquake focal zones. In this regard, studying helium contents in groundwater is of particular importance – anomalous concentrations of helium are typical of fault zones, and helium concentration variations in time can be referred to as earthquake precursors. Our study was focused on the distribution of helium in groundwaters of the Altai Republic and aimed to determine and justify positioning of permanent monitoring sites for investigation of earthquake precursors. During the field study, groundwater samples were taken from wells and springs located within the area covered by the established state monitoring network (GONS). Groundwater aquifers and water-bearing zones from Quaternary to Proterozoic ages were sampled. Analysis of the groundwater samples shows spatial variations of helium concentration in the study area. Water samples from fault zones have increased concentrations of helium. The concentration of helium is high in the groundwater from the Chuya artesian basin, i.e. near the epicentral zone of the M 7.5 Altai (Chuya) earthquake of September 27, 2003.
{"title":"Helium in groundwaters of the Altai Republic","authors":"E. Dutova, V. Kats, A. Shitov, A. Surnin, V. Molokov","doi":"10.5800/gt-2020-11-3-0497","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0497","url":null,"abstract":". This study of groundwaters of the Altai Republic is relevant due to the need to identify earthquake precursors in seismically active zones of the study area. Chemical composition of groundwater is widely known as an indicator of seismic processes, which changes in future earthquake focal zones. In this regard, studying helium contents in groundwater is of particular importance – anomalous concentrations of helium are typical of fault zones, and helium concentration variations in time can be referred to as earthquake precursors. Our study was focused on the distribution of helium in groundwaters of the Altai Republic and aimed to determine and justify positioning of permanent monitoring sites for investigation of earthquake precursors. During the field study, groundwater samples were taken from wells and springs located within the area covered by the established state monitoring network (GONS). Groundwater aquifers and water-bearing zones from Quaternary to Proterozoic ages were sampled. Analysis of the groundwater samples shows spatial variations of helium concentration in the study area. Water samples from fault zones have increased concentrations of helium. The concentration of helium is high in the groundwater from the Chuya artesian basin, i.e. near the epicentral zone of the M 7.5 Altai (Chuya) earthquake of September 27, 2003.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"1 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"74261702","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0492
N. Palshin, A. Ivanenko, D. Alekseev
An innovative technology of anomalous magnetic field inversion was applied to construct 2D models of the magnetic layer using three profiles crossing the southern, central and northern parts of the Kuril Island Arc. In the frontal area of the northern and southern parts, a zone of increased effective magnetization is clearly distinguished. In the central part of the island arc, increased magnetization is much less pronounced. Anomalous zones of positive effective magnetization have a deep part, the so-called "serpentinite wedge". The inhomogeneous lateral structure of the magnetic layer of the Kuril Island Arc suggests differences in the fluid regime and is reflected in the distribution of modern seismicity.
{"title":"Inhomogeneous structure of magnetic layer of the Kuril Island Arc","authors":"N. Palshin, A. Ivanenko, D. Alekseev","doi":"10.5800/gt-2020-11-3-0492","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0492","url":null,"abstract":"An innovative technology of anomalous magnetic field inversion was applied to construct 2D models of the magnetic layer using three profiles crossing the southern, central and northern parts of the Kuril Island Arc. In the frontal area of the northern and southern parts, a zone of increased effective magnetization is clearly distinguished. In the central part of the island arc, increased magnetization is much less pronounced. Anomalous zones of positive effective magnetization have a deep part, the so-called \"serpentinite wedge\". The inhomogeneous lateral structure of the magnetic layer of the Kuril Island Arc suggests differences in the fluid regime and is reflected in the distribution of modern seismicity.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"90 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81234842","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0488
M. G. Leonov, G. Kocharyan, A. Revuzhenko, S. Lavrikov
Block-granular geological objects and rock volumetric mobility indicators are described. The mechanisms of structural and material reworking of rocks are considered in relation to the formation of a discrete tectonic structure of rocks and changes in the shapes of the geological bodies, which take place without rupturing the rock surfaces bounding these bodies and provide for the volumetric tectonic flow of solid rocks. Based on the study of natural objects and their comparison with the theoretical and experimental data on solid mechanics and geomechanics, it is suggested that one of the triggers for the volumetric disintegration of rock masses is rock fatigue damage (a fundamental phenomenon of solid-state physics). The disintegrated rocks behave according to the laws of mechanics of granular materials and mesomechanics. This study is of both theoretical and pragmatic importance as it contributes to the understanding of the regional geological features and provides new knowledge on the formation of crystalline protrusions known among the main hydrocarbon reservoirs within the basements of various geologic structures.
{"title":"Tectonics of rock loosening: geological data and physics of the process","authors":"M. G. Leonov, G. Kocharyan, A. Revuzhenko, S. Lavrikov","doi":"10.5800/gt-2020-11-3-0488","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0488","url":null,"abstract":"Block-granular geological objects and rock volumetric mobility indicators are described. The mechanisms of structural and material reworking of rocks are considered in relation to the formation of a discrete tectonic structure of rocks and changes in the shapes of the geological bodies, which take place without rupturing the rock surfaces bounding these bodies and provide for the volumetric tectonic flow of solid rocks. Based on the study of natural objects and their comparison with the theoretical and experimental data on solid mechanics and geomechanics, it is suggested that one of the triggers for the volumetric disintegration of rock masses is rock fatigue damage (a fundamental phenomenon of solid-state physics). The disintegrated rocks behave according to the laws of mechanics of granular materials and mesomechanics. This study is of both theoretical and pragmatic importance as it contributes to the understanding of the regional geological features and provides new knowledge on the formation of crystalline protrusions known among the main hydrocarbon reservoirs within the basements of various geologic structures.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"47 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83584648","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0491
N. Sharov, L. Bakunovich, B. Belashev, V. Zhuravlev, M. Nilov
The study of the White Sea region and the adjacent area aimed to model the structure of the crystalline portion of the crust at the contact of the northeastern slope of the Fennoscandian Shield and the Russian Plate. Modeling was based on geological, geophysical and DSS profile data, State Geological Map of the Russian Federation (scale 1:1 000 000), Explanatory Notes to Sheets Q-35, 36, 37, and 38 (third generation, 2009), and Tectonic Map of the White Sea and Adjacent Areas (2012). A model was constructed using GIS INTEGRO software (VNIIgeosystems), specifically its procedures for calculation and visualization of 2D and 3D models showing crust density and magnetic fields. The model of the study area shows the structure of the crust and the characteristics of its horizons.
{"title":"Geological-geophysical models of the crust for the White Sea region","authors":"N. Sharov, L. Bakunovich, B. Belashev, V. Zhuravlev, M. Nilov","doi":"10.5800/gt-2020-11-3-0491","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0491","url":null,"abstract":"The study of the White Sea region and the adjacent area aimed to model the structure of the crystalline portion of the crust at the contact of the northeastern slope of the Fennoscandian Shield and the Russian Plate. Modeling was based on geological, geophysical and DSS profile data, State Geological Map of the Russian Federation (scale 1:1 000 000), Explanatory Notes to Sheets Q-35, 36, 37, and 38 (third generation, 2009), and Tectonic Map of the White Sea and Adjacent Areas (2012). A model was constructed using GIS INTEGRO software (VNIIgeosystems), specifically its procedures for calculation and visualization of 2D and 3D models showing crust density and magnetic fields. The model of the study area shows the structure of the crust and the characteristics of its horizons.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"80 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90403293","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0487
I. Derbeko, A. Chugaev
. Granitoids of the Magdagachi complex were studied using new and published petrochemical, geochemical and isotopic (Sm-Nd, Rb-Sr) data. Granitoid samples were taken from the southern frame of the eastern flank of the Mongol-Okhotsk orogenic belt (MOOB). Their analysis shows increased concentrations of Sr, Ba, Eu; reduced concentrations of Nb, Ta; abnormally low concentrations of HREE, Y and Yb; significant fractionation of REE; and high Sr/Y ratios. Therefore, the Magdagachi granitoids are "classical" adakites that may have formed at a depth of more than 45 km due to melting of eclogite with a garnet content of 20–50 %. Such conditions could exist under subduction as a result of melting of the frontal or lateral parts of the slab in subduction windows formed during oblique subduction at an orthogonal sinking angle. Highly metamorphosed lower crust Precambrian formations were also melted, and a source of parental melts could have been composed of both the mantle and crustal materials. Two tectonic scenarios are proposed that could have been accompanied by the formation of Magdagachi granitoids. Both scenarios refer to subduction processes, but differ in interactions between various regional structures in the Late Mesozoic.
{"title":"Late Mesozoic adakite granites of the southern frame of the eastern flank of the Mongol-Okhotsk orogenic belt: material composition and geodynamic conditions of formation","authors":"I. Derbeko, A. Chugaev","doi":"10.5800/gt-2020-11-3-0487","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0487","url":null,"abstract":". Granitoids of the Magdagachi complex were studied using new and published petrochemical, geochemical and isotopic (Sm-Nd, Rb-Sr) data. Granitoid samples were taken from the southern frame of the eastern flank of the Mongol-Okhotsk orogenic belt (MOOB). Their analysis shows increased concentrations of Sr, Ba, Eu; reduced concentrations of Nb, Ta; abnormally low concentrations of HREE, Y and Yb; significant fractionation of REE; and high Sr/Y ratios. Therefore, the Magdagachi granitoids are \"classical\" adakites that may have formed at a depth of more than 45 km due to melting of eclogite with a garnet content of 20–50 %. Such conditions could exist under subduction as a result of melting of the frontal or lateral parts of the slab in subduction windows formed during oblique subduction at an orthogonal sinking angle. Highly metamorphosed lower crust Precambrian formations were also melted, and a source of parental melts could have been composed of both the mantle and crustal materials. Two tectonic scenarios are proposed that could have been accompanied by the formation of Magdagachi granitoids. Both scenarios refer to subduction processes, but differ in interactions between various regional structures in the Late Mesozoic.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"96 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76988412","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0495
A. Darin, G. Chu, Q. Sun, V. Babich, I. Kalugin, T. Markovich, V. S. Novikov, F. Darin, Y. Rakshun
. Core samples taken from the bottom sediments of the glacial Lake Kucherla (Gorny Altai, Russia) clearly show annual layers represented by glacial clays. In our study, age-depth modeling is based the varve chronology and Cs-137, Pb-210 and C-14 isotope data. Our model is a highly accurate and reliable demonstration of the annual sedimentation history within the past 1400 years. The time series of geochemical indicators of climate change were obtained by synchrotron radiation micro X-ray fluorescence (SR-µXRF) core scanning. Instrumental meteorological observations from 1940 to 2016 were used to construct transfer functions for the average annual temperatures and atmospheric precipitation amounts. A geochemical trace of a catastrophic seismic event, the Mongolian earthquake of 1761, was found in the cross-section of the bottom sediments.
{"title":"Archive data on climate changes and seismic events in glacial clays of Lake Kucherla (Altai region, Russia)","authors":"A. Darin, G. Chu, Q. Sun, V. Babich, I. Kalugin, T. Markovich, V. S. Novikov, F. Darin, Y. Rakshun","doi":"10.5800/gt-2020-11-3-0495","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0495","url":null,"abstract":". Core samples taken from the bottom sediments of the glacial Lake Kucherla (Gorny Altai, Russia) clearly show annual layers represented by glacial clays. In our study, age-depth modeling is based the varve chronology and Cs-137, Pb-210 and C-14 isotope data. Our model is a highly accurate and reliable demonstration of the annual sedimentation history within the past 1400 years. The time series of geochemical indicators of climate change were obtained by synchrotron radiation micro X-ray fluorescence (SR-µXRF) core scanning. Instrumental meteorological observations from 1940 to 2016 were used to construct transfer functions for the average annual temperatures and atmospheric precipitation amounts. A geochemical trace of a catastrophic seismic event, the Mongolian earthquake of 1761, was found in the cross-section of the bottom sediments.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"79 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76628483","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0490
I. Denisenko, O. Lunina
. Ground-penetrating radar (GPR) surveys were performed in the Sarma segment of the Primorsky fault between the settlements of Shida and Kurma. This segment belongs to one of the largest structures of the Baikal rift and was active in Late Quaternary (Early Holocene). The study aimed to reconstruct vertical displacement amplitudes and dip angles of fractures along the fault segment, clarify its kinematic type, and estimate a maximum magnitude of earthquakes that may occur in the study area. The GPR equipment set included an OKO-2 georadar and AB-250M and ABDL-Triton shielded antennas. The GPR surveys were supported by morphostructural and tectonophysical methods. Based on the interpretation of the geophysical survey data and satellite images, faults associated with the Sarma paleoseismic dislocation were mapped. Their total length amounts to 14 km. According to the GPR survey data, one-stage vertical displacements show normal faulting and vary from SW to NE from 4.4 to 7.7 m. Paleo-earthquake magnitudes calculated from the maximum displacement values (Mw=7.2, and Мs=7.4) suggest that potential earthquakes in the Primorsky fault zone may be stronger than previously assumed.
{"title":"Late Quarternary displacements along the Sarma segment of the Primorsky fault based on gpr survey data (Baikal rift)","authors":"I. Denisenko, O. Lunina","doi":"10.5800/gt-2020-11-3-0490","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0490","url":null,"abstract":". Ground-penetrating radar (GPR) surveys were performed in the Sarma segment of the Primorsky fault between the settlements of Shida and Kurma. This segment belongs to one of the largest structures of the Baikal rift and was active in Late Quaternary (Early Holocene). The study aimed to reconstruct vertical displacement amplitudes and dip angles of fractures along the fault segment, clarify its kinematic type, and estimate a maximum magnitude of earthquakes that may occur in the study area. The GPR equipment set included an OKO-2 georadar and AB-250M and ABDL-Triton shielded antennas. The GPR surveys were supported by morphostructural and tectonophysical methods. Based on the interpretation of the geophysical survey data and satellite images, faults associated with the Sarma paleoseismic dislocation were mapped. Their total length amounts to 14 km. According to the GPR survey data, one-stage vertical displacements show normal faulting and vary from SW to NE from 4.4 to 7.7 m. Paleo-earthquake magnitudes calculated from the maximum displacement values (Mw=7.2, and Мs=7.4) suggest that potential earthquakes in the Primorsky fault zone may be stronger than previously assumed.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"12 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83297060","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 : 2020-09-23DOI: 10.5800/gt-2020-11-3-0496
S. Rasskazov, A. Ilyasova, I. Chuvashova, S. Bornyakov, A. I. Orgilyianov, S. N. Kovalenko, A. Seminsky, E. P. Popov, E. Chebykin
The southern deformed edge of the Siberian paleocontinent is studied for zoning the disturbance of 234U/238U cyclic equilibrium in groundwaters discharged to the accreted Khamardaban terrane. A relationship is established between vertical variations of 234U/238U (ОА4/8) activity ratios and the hydrogeochemical zoning of groundwaters. Lateral ОА4/8 zoning of groundwaters in the basement rocks and sedimentary cover of the Siberian platform is described. It is emphasized that an important role is played by the water propagating from the South Baikal reservoir (SBR) (ОА4/8 = 1.95–1.99; U content = 0.44–0.46 μg/L) under the shore of Lake Baikal. It is suggested that the lateral advancement of the SBR water is facilitated by the development of low-angle (weakened by rifting) fractures of the Angara thrust fault, as well as subvertical fractures in the shear zone of the Main Sayan Fault. Monitoring data on the study area show that the ratios of the groundwaters components vary in time due to Cherdyntsev – Chalov deformational effect, chemical interaction of the waters and evaporites, and mixing of the groundwaters with contrasting hydrogeochemical signatures.
{"title":"Hydrogeochemical zoning of uranium isotopes (234U/ 238U) in the Southern Siberian paleocontinent: the role of the South Baikal reservoir in the groundwater formation","authors":"S. Rasskazov, A. Ilyasova, I. Chuvashova, S. Bornyakov, A. I. Orgilyianov, S. N. Kovalenko, A. Seminsky, E. P. Popov, E. Chebykin","doi":"10.5800/gt-2020-11-3-0496","DOIUrl":"https://doi.org/10.5800/gt-2020-11-3-0496","url":null,"abstract":"The southern deformed edge of the Siberian paleocontinent is studied for zoning the disturbance of 234U/238U cyclic equilibrium in groundwaters discharged to the accreted Khamardaban terrane. A relationship is established between vertical variations of 234U/238U (ОА4/8) activity ratios and the hydrogeochemical zoning of groundwaters. Lateral ОА4/8 zoning of groundwaters in the basement rocks and sedimentary cover of the Siberian platform is described. It is emphasized that an important role is played by the water propagating from the South Baikal reservoir (SBR) (ОА4/8 = 1.95–1.99; U content = 0.44–0.46 μg/L) under the shore of Lake Baikal. It is suggested that the lateral advancement of the SBR water is facilitated by the development of low-angle (weakened by rifting) fractures of the Angara thrust fault, as well as subvertical fractures in the shear zone of the Main Sayan Fault. Monitoring data on the study area show that the ratios of the groundwaters components vary in time due to Cherdyntsev – Chalov deformational effect, chemical interaction of the waters and evaporites, and mixing of the groundwaters with contrasting hydrogeochemical signatures.","PeriodicalId":44925,"journal":{"name":"Geodynamics & Tectonophysics","volume":"44 1","pages":""},"PeriodicalIF":0.7,"publicationDate":"2020-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86531396","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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