Pub Date : 2024-03-14DOI: 10.1134/s0016852123060043
O. V. Grushevskaya, A. V. Soloviev, E. A. Vasilyeva, E. P. Petrushina, I. V. Aksenov, A. R. Yusupova, S. V. Shimanskiy, I. N. Peshkova
Abstract
Based on the results of field complex geophysical studies in the northwestern part of the Russian sector of the Barents Sea shelf, as well as on the processing and comprehensive interpretation of new and retrospective geophysical materials in the volume of 25 500 linear kilometers and deep well drilling data in the section of the Barents Sea sedimentary cover, regional tectonostratigraphic units were identified between reflecting horizons (RH): (i) a Paleozoic complex (between RH VI(PR?) and RH I2(P‒T)); (ii) a Triassic complex (between RH I2(P‒T) and RH B(T‒J)); (iii) a Jurassic complex (between RH B(T‒J) and RH C′(J3‒K1)); and (iv) a Cretaceous‒Cenozoic complex (between RH V′(J3‒K1) and the Barents Sea floor). According to the structural analysis results, three structural floors were established: the lower structural level, which includes Riphean terrigenous-effusive deposits and Lower Paleozoic‒Lower Permian terrigenous-carbonate deposits; the middle structural level is formed mainly by Upper Devonian‒Lower Permian carbonate deposits; the upper structural level combines Lower and Upper Permian terrigenous deposits and Mesozoic–Cenozoic deposits. This article presents a new tectonic model of the Barents Sea region, including elements of all structural levels with sublevels. In accordance with the tectonic zoning, paleostructural and paleotectonic analyses, the article outlines the main stages of the Barents Sea shelf development: stage of the Late Proterozoic compression and Early–Middle Paleozoic continental rifting (I), a Late Paleozoic stabilization stage (II), an Early Mesozoic tectonogenesis stage (III), a Middle Mesozoic thermal subsidence stage (IV), a Late Jurassic stabilization stage (V), a Cretaceous subsidence stage (VI), and the final stage as a Cenozoic uplift of a large part of the Barents Sea shelf (VII). In the northwestern part of the Russian sector of the Barents Sea shelf, synchronous subsidence of the sedimentary cover basement took place, associated with spreading and formation of the Arctic Ocean.
{"title":"The Tectonics of the Continental Barents Sea Shelf (Russia): The Formation Stages of the Basement and Sedimentary Cover","authors":"O. V. Grushevskaya, A. V. Soloviev, E. A. Vasilyeva, E. P. Petrushina, I. V. Aksenov, A. R. Yusupova, S. V. Shimanskiy, I. N. Peshkova","doi":"10.1134/s0016852123060043","DOIUrl":"https://doi.org/10.1134/s0016852123060043","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Based on the results of field complex geophysical studies in the northwestern part of the Russian sector of the Barents Sea shelf, as well as on the processing and comprehensive interpretation of new and retrospective geophysical materials in the volume of 25 500 linear kilometers and deep well drilling data in the section of the Barents Sea sedimentary cover, regional tectonostratigraphic units were identified between reflecting horizons (RH): (i) a Paleozoic complex (between RH VI(PR?) and RH I<sub>2</sub>(P‒T)); (ii) a Triassic complex (between RH I<sub>2</sub>(P‒T) and RH B(T‒J)); (iii) a Jurassic complex (between RH B(T‒J) and RH C′(J<sub>3</sub>‒K<sub>1</sub>)); and (iv) a Cretaceous‒Cenozoic complex (between RH V′(J<sub>3</sub>‒K<sub>1</sub>) and the Barents Sea floor). According to the structural analysis results, three structural floors were established: the lower structural level, which includes Riphean terrigenous-effusive deposits and Lower Paleozoic‒Lower Permian terrigenous-carbonate deposits; the middle structural level is formed mainly by Upper Devonian‒Lower Permian carbonate deposits; the upper structural level combines Lower and Upper Permian terrigenous deposits and Mesozoic–Cenozoic deposits. This article presents a new tectonic model of the Barents Sea region, including elements of all structural levels with sublevels. In accordance with the tectonic zoning, paleostructural and paleotectonic analyses, the article outlines the main stages of the Barents Sea shelf development: stage of the Late Proterozoic compression and Early–Middle Paleozoic continental rifting (I), a Late Paleozoic stabilization stage (II), an Early Mesozoic tectonogenesis stage (III), a Middle Mesozoic thermal subsidence stage (IV), a Late Jurassic stabilization stage (V), a Cretaceous subsidence stage (VI), and the final stage as a Cenozoic uplift of a large part of the Barents Sea shelf (VII). In the northwestern part of the Russian sector of the Barents Sea shelf, synchronous subsidence of the sedimentary cover basement took place, associated with spreading and formation of the Arctic Ocean.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"22 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140150457","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-14DOI: 10.1134/s0016852123060031
G. N. Antonovskaya, Ya. V. Konechnaya, I. M. Basakina
Abstract
The influence of the mid-oceanic ridges (MORs), including the Gakkel Ridge and the Knipovich Ridge–Lena Trough system on the seismicity of the Novaya Zemlya archipelago area for 1980‒2022 is considered. For each geological element under consideration, seismic catalogs with a single unified magnitude mbISC for an equivalent comparison of information were compiled, the annual seismic energy was calculated, and plots of its distribution by year were constructed. Analytical modeling based on the Elsasser model describing the process of local stress transfer in a rigid elastic lithosphere underlain by a viscous asthenosphere was performed, and quantitative calculations of the disturbance propagations from MORs were made. The time intervals through which disturbances from MORs reach the Novaya Zemlya archipelago are 1‒2 years for the Knipovich Ridge–Lena Trough system and 3‒5 years for the Gakkel Ridge. The maximum joint contribution to the level of seismic activity of various geological and tectonic structures of the MORs can reach 40‒60% of the applied disturbance, which is a sufficient condition for the influence on seismicity of the Novaya Zemlya orogen. The most geodynamically active structures and zones of tectonic stress concentration were identified.
{"title":"The Influence of Mid-Oceanic Ridges on the Seismicity of the Novaya Zemlya Archipelago","authors":"G. N. Antonovskaya, Ya. V. Konechnaya, I. M. Basakina","doi":"10.1134/s0016852123060031","DOIUrl":"https://doi.org/10.1134/s0016852123060031","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The influence of the mid-oceanic ridges (MORs), including the Gakkel Ridge and the Knipovich Ridge–Lena Trough system on the seismicity of the Novaya Zemlya archipelago area for 1980‒2022 is considered. For each geological element under consideration, seismic catalogs with a single unified magnitude mb<sub><i>ISC</i></sub> for an equivalent comparison of information were compiled, the annual seismic energy was calculated, and plots of its distribution by year were constructed. Analytical modeling based on the Elsasser model describing the process of local stress transfer in a rigid elastic lithosphere underlain by a viscous asthenosphere was performed, and quantitative calculations of the disturbance propagations from MORs were made. The time intervals through which disturbances from MORs reach the Novaya Zemlya archipelago are 1‒2 years for the Knipovich Ridge–Lena Trough system and 3‒5 years for the Gakkel Ridge. The maximum joint contribution to the level of seismic activity of various geological and tectonic structures of the MORs can reach 40‒60% of the applied disturbance, which is a sufficient condition for the influence on seismicity of the Novaya Zemlya orogen. The most geodynamically active structures and zones of tectonic stress concentration were identified.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"22 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140150359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-14DOI: 10.1134/s0016852123060067
T. K. Pinegina, A. I. Kozhurin
Abstract
The geologic structure of the late Holocene accumulative marine terrace on the Kamchatka Bay coast (Kamchatka Peninsula) has been studied. The obtained age and relative hypsometric position of beach ridges composing the terrace have made it possible to identify two types of vertical coast movements: periodic fast (coseismic) movements and slow time-scale uplift or subsidence. High-amplitude vertical coseismic movements (up to 1‒2 m) occur once every ~1200‒1300 years, on average, while slow movements occur at an average rate of from a fraction of a millimeter to ~2 mm/yr. Coseismic movements as relaxation of elastic deformations accumulated during the interseismic interval of the seismic cycle neither exceed them nor accumulate. Slow movements set the general trend of vertical coast deformations. It is assumed that subsiding central parts of the eastern bays of the Kamchatka Peninsula (Avachinsky, Kronotsky, and Kamchatsky) and depressions between the eastern peninsulas (Kronotsky and Shipunsky) and the main Kamchatka massif form an arc-parallel extension zone located in the closest proximity to the deep-water trench and that the extension is caused by a migration of the subducted part of the Pacific Plate toward the Pacific Ocean. Under the eastern Shipunsky and Kronotsky peninsulas, the arc-normal extension of the earth’s crust of the Kamchatka segment of the Kuril–Kamchatka island arc is replaced by a transverse compression zone.
{"title":"Coseismic and Tectonic Time-Scale Deformations of an Island Arc Based on the Studies of the East Coast of the Kamchatka Peninsula (Far East, Russia)","authors":"T. K. Pinegina, A. I. Kozhurin","doi":"10.1134/s0016852123060067","DOIUrl":"https://doi.org/10.1134/s0016852123060067","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The geologic structure of the late Holocene accumulative marine terrace on the Kamchatka Bay coast (Kamchatka Peninsula) has been studied. The obtained age and relative hypsometric position of beach ridges composing the terrace have made it possible to identify two types of vertical coast movements: periodic fast (coseismic) movements and slow time-scale uplift or subsidence. High-amplitude vertical coseismic movements (up to 1‒2 m) occur once every ~1200‒1300 years, on average, while slow movements occur at an average rate of from a fraction of a millimeter to ~2 mm/yr. Coseismic movements as relaxation of elastic deformations accumulated during the interseismic interval of the seismic cycle neither exceed them nor accumulate. Slow movements set the general trend of vertical coast deformations. It is assumed that subsiding central parts of the eastern bays of the Kamchatka Peninsula (Avachinsky, Kronotsky, and Kamchatsky) and depressions between the eastern peninsulas (Kronotsky and Shipunsky) and the main Kamchatka massif form an arc-parallel extension zone located in the closest proximity to the deep-water trench and that the extension is caused by a migration of the subducted part of the Pacific Plate toward the Pacific Ocean. Under the eastern Shipunsky and Kronotsky peninsulas, the arc-normal extension of the earth’s crust of the Kamchatka segment of the Kuril–Kamchatka island arc is replaced by a transverse compression zone.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"99 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140150364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-14DOI: 10.1134/s0016852123060079
V. G. Trifonov, S. Yu. Sokolov, S. A. Sokolov, S. V. Maznev, K. I. Yushin, S. Demberel
<h3 data-test="abstract-sub-heading">Abstract</h3><p>The Khangai plume is situated under Central and Eastern Mongolia and is a mantle volume with significantly reduced longitudinal (<i>P</i>) wave velocities. The plume has been identified as a result of the analysis of the MITP08 volumetric model of <i>P</i>-wave velocity variations, representing the deviations of <i>P</i>-wave velocities from the average values (δ<i>V</i><sub>p</sub>), given as a percentage. The lithospheric mantle is thinned to ca. 50 km above the plume. Especially low velocities (δ<i>V</i><sub>p</sub> ≤ –0.6%) are found in the sublithospheric mantle up to a depth of 400 km. The main body of the plume is located under the Khangai Highland and extends northward to the edge of Southern Siberia. The Khentei branch of the plume that is located SE of the Khentei Highland is connected with the main plume body at depths of 800–1000 km. Branches of the plume and its Khentei branch extend into Transbaikalia. The area of the plume decreases with depth, and its deepest part (1250–1300 km) is located under the southern Khangai Highland. The main body of the Khangai plume is expressed on the land surface by the Cenozoic uplift reaching 3500–4000 m in the southern Khangai Highland. From the SE, the Khangai plume and its Khentei branch territory are limited by Late Cenozoic troughs stretching along the southeastern border of Mongolia. From other sides, the Khangai uplift is bounded by a C-shaped belt of basins. The belt includes the southwestern part of the Baikal Rift Zone, the Tunka and Tuva Basins in the north, the Ubsu-Nur Basin and the Basin of Big Lakes in the west, and the Valley of Lakes in the south. The basins are filled with lacustrine and fluvial deposits of the Late Oligocene to Pliocene. In the Quaternary, the South and Central Baikal Basins, which existed as early as the Early Paleogene, became a part of the Baikal Rift, and the other basins were involved in the general uplift of the region. The structural paragenesis of the Khangai uplift and the surrounding basins is caused by the influence of the Khangai plume. On the territory above the plume, including its Khentei and Transbaikalia branches, the Cenozoic basaltic plume volcanism occurred, inheriting the Cretaceous volcanic manifestations in some places. The structural paragenesis associated with the Khangai plume is combined with the structural paragenesis produced by lithospheric plate interaction. The latter is expressed the best of all by active faults, but developed synchronously to the plume paragenesis. The active fault kinematics shows that the eastern and central parts of the region developed in the transpression conditions and the north-eastern part developed in conditions of extension and transtension. The Khangai plume is connected at depth with the Tibetan plume, which is situated under the central and eastern Tibetan Plateau north of the Lhasa block. The Tibetan plume has the shape of a funnel rising from dept
{"title":"Khangai Intramantle Plume (Mongolia): 3D Model, Influence on Cenozoic Tectonics, and Comparative Analysis","authors":"V. G. Trifonov, S. Yu. Sokolov, S. A. Sokolov, S. V. Maznev, K. I. Yushin, S. Demberel","doi":"10.1134/s0016852123060079","DOIUrl":"https://doi.org/10.1134/s0016852123060079","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>The Khangai plume is situated under Central and Eastern Mongolia and is a mantle volume with significantly reduced longitudinal (<i>P</i>) wave velocities. The plume has been identified as a result of the analysis of the MITP08 volumetric model of <i>P</i>-wave velocity variations, representing the deviations of <i>P</i>-wave velocities from the average values (δ<i>V</i><sub>p</sub>), given as a percentage. The lithospheric mantle is thinned to ca. 50 km above the plume. Especially low velocities (δ<i>V</i><sub>p</sub> ≤ –0.6%) are found in the sublithospheric mantle up to a depth of 400 km. The main body of the plume is located under the Khangai Highland and extends northward to the edge of Southern Siberia. The Khentei branch of the plume that is located SE of the Khentei Highland is connected with the main plume body at depths of 800–1000 km. Branches of the plume and its Khentei branch extend into Transbaikalia. The area of the plume decreases with depth, and its deepest part (1250–1300 km) is located under the southern Khangai Highland. The main body of the Khangai plume is expressed on the land surface by the Cenozoic uplift reaching 3500–4000 m in the southern Khangai Highland. From the SE, the Khangai plume and its Khentei branch territory are limited by Late Cenozoic troughs stretching along the southeastern border of Mongolia. From other sides, the Khangai uplift is bounded by a C-shaped belt of basins. The belt includes the southwestern part of the Baikal Rift Zone, the Tunka and Tuva Basins in the north, the Ubsu-Nur Basin and the Basin of Big Lakes in the west, and the Valley of Lakes in the south. The basins are filled with lacustrine and fluvial deposits of the Late Oligocene to Pliocene. In the Quaternary, the South and Central Baikal Basins, which existed as early as the Early Paleogene, became a part of the Baikal Rift, and the other basins were involved in the general uplift of the region. The structural paragenesis of the Khangai uplift and the surrounding basins is caused by the influence of the Khangai plume. On the territory above the plume, including its Khentei and Transbaikalia branches, the Cenozoic basaltic plume volcanism occurred, inheriting the Cretaceous volcanic manifestations in some places. The structural paragenesis associated with the Khangai plume is combined with the structural paragenesis produced by lithospheric plate interaction. The latter is expressed the best of all by active faults, but developed synchronously to the plume paragenesis. The active fault kinematics shows that the eastern and central parts of the region developed in the transpression conditions and the north-eastern part developed in conditions of extension and transtension. The Khangai plume is connected at depth with the Tibetan plume, which is situated under the central and eastern Tibetan Plateau north of the Lhasa block. The Tibetan plume has the shape of a funnel rising from dept","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"19 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140150439","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1134/s0016852123070099
T. V. Matveeva, A. O. Chazov, Yu. Yu. Smirnov
Abstract—
The conditions for the formation of gas hydrates associated with subsea permafrost in the Kara Sea have been predicted based on numerical modeling. The forecast of the distribution of the relic submarine permafrost and related methane hydrate stability zone is given on the basis of solving the equation of thermal conductivity. According to modeling data, an extensive thermobaric relic submarine permafrost zone is predicted within the Kara Sea shelf. The greatest thickness (up to 600 m) of the permafrost is confined to the Taimyr shelf. Based on the results of the analysis of our model, drilling and seismic data, the southwestern shelf of the Kara Sea has insular or sporadic permafrost. In the northeastern part, the nature of the permafrost is also discontinuous, despite the greater thickness of the frozen strata. For the first time, accumulations of cryogenic gas hydrates on the Taimyr shelf have been characterized. The latest drilling data, seismic data reinterpretation, and numerical modeling have shown that the gas hydrate reservoir is confined to unconformably occurring Silurian–Devonian and underlying Triassic–Jurassic strata. The thickness of the gas hydrate reservoir varies from 800 to 1100 m. Based on the interpretation of CDP data and their comparison with model calculations, frozen deposits, and sub-permafrost traps of stratigraphic, anticline and anticline-stratigraphic types were identified for the first time. These pioneering studies allowed us to characterize the thickness and morphology of the gas hydrate reservoir, give a preliminary seismostratigraphic reference, and identify potentially gas hydrate-bearing structures. Due to the favorable thermobaric and permafrost-geothermal conditions, most of the identified traps may turn out to be sub-permafrost accumulations of gas hydrates. In total, at least five potential accumulations of gas hydrates were discovered, confined to structural depressions; the Uedineniya Trough and its side included the Egiazarov Step and North Mikhailovskaya Depression.
{"title":"The Geological Characteristics of a Subpermafrost Gas Hydrate Reservoir on the Taimyr Shelf of the Kara Sea (Eastern Arctic)","authors":"T. V. Matveeva, A. O. Chazov, Yu. Yu. Smirnov","doi":"10.1134/s0016852123070099","DOIUrl":"https://doi.org/10.1134/s0016852123070099","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">\u0000<b>Abstract</b>—</h3><p>The conditions for the formation of gas hydrates associated with subsea permafrost in the Kara Sea have been predicted based on numerical modeling. The forecast of the distribution of the relic submarine permafrost and related methane hydrate stability zone is given on the basis of solving the equation of thermal conductivity. According to modeling data, an extensive thermobaric relic submarine permafrost zone is predicted within the Kara Sea shelf. The greatest thickness (up to 600 m) of the permafrost is confined to the Taimyr shelf. Based on the results of the analysis of our model, drilling and seismic data, the southwestern shelf of the Kara Sea has insular or sporadic permafrost. In the northeastern part, the nature of the permafrost is also discontinuous, despite the greater thickness of the frozen strata. For the first time, accumulations of cryogenic gas hydrates on the Taimyr shelf have been characterized. The latest drilling data, seismic data reinterpretation, and numerical modeling have shown that the gas hydrate reservoir is confined to unconformably occurring Silurian–Devonian and underlying Triassic–Jurassic strata. The thickness of the gas hydrate reservoir varies from 800 to 1100 m. Based on the interpretation of CDP data and their comparison with model calculations, frozen deposits, and sub-permafrost traps of stratigraphic, anticline and anticline-stratigraphic types were identified for the first time. These pioneering studies allowed us to characterize the thickness and morphology of the gas hydrate reservoir, give a preliminary seismostratigraphic reference, and identify potentially gas hydrate-bearing structures. Due to the favorable thermobaric and permafrost-geothermal conditions, most of the identified traps may turn out to be sub-permafrost accumulations of gas hydrates. In total, at least five potential accumulations of gas hydrates were discovered, confined to structural depressions; the Uedineniya Trough and its side included the Egiazarov Step and North Mikhailovskaya Depression.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"37 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1134/s0016852123070075
E. A. Gusev, D. E. Artemieva, A. Yu. Komarov, A. A. Krylov, D. M. Urvantsev, A. N. Usov, E. A. Zykov
Abstract
Modern ideas about the tectonics of the Eurasian continental margin are considered. Cratons, fold belts, platforms, and sedimentary basins are briefly characterized. A significant part of the Arctic continental margins is represented by folded structures of different ages. In the course of geological evolution, tectonic structures successively formed, modified and died off, on which the processes of rifting and ocean formation were superimposed. Multidirectional tectonic movements, both vertical and horizontal, which led to the formation of the contours of oceanic basins and the ridges separating them, also influenced the continental margin. The destruction of the continental crust of the outer part of the continental shelf resulted in the formation of graben-like and rift troughs. The history of the Arctic oceanic basin began with the opening of the straits that connected the once isolated basin, the waters of which were largely desalinated. The latest stage of development was characterized by processes in which the transgressions and regressions of the Arctic Basin, the development and degradation of terrestrial and underground glaciation, and other processes played a leading role.
{"title":"Tectonic Framework of the Eurasian Arctic Continental Margin","authors":"E. A. Gusev, D. E. Artemieva, A. Yu. Komarov, A. A. Krylov, D. M. Urvantsev, A. N. Usov, E. A. Zykov","doi":"10.1134/s0016852123070075","DOIUrl":"https://doi.org/10.1134/s0016852123070075","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Modern ideas about the tectonics of the Eurasian continental margin are considered. Cratons, fold belts, platforms, and sedimentary basins are briefly characterized. A significant part of the Arctic continental margins is represented by folded structures of different ages. In the course of geological evolution, tectonic structures successively formed, modified and died off, on which the processes of rifting and ocean formation were superimposed. Multidirectional tectonic movements, both vertical and horizontal, which led to the formation of the contours of oceanic basins and the ridges separating them, also influenced the continental margin. The destruction of the continental crust of the outer part of the continental shelf resulted in the formation of graben-like and rift troughs. The history of the Arctic oceanic basin began with the opening of the straits that connected the once isolated basin, the waters of which were largely desalinated. The latest stage of development was characterized by processes in which the transgressions and regressions of the Arctic Basin, the development and degradation of terrestrial and underground glaciation, and other processes played a leading role.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"82 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097171","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1134/s0016852123070117
V. A. Poselov, A. S. Zholondz, O. E. Smirnov, A. L. Piskarev, S. M. Zholondz, V. A. Savin, A. G. Zinchenko, N. E. Leonova, A. A. Kireev
Abstract—
The Chukchi Borderland is a tectonic unit of the eastern part of the Arctic continental margin of Eurasia that is part of the complex of the Central Arctic rises, along with the Lomonosov Ridge, the Alpha‒Mendeleev Rise, the Podvodnikov, Chukchi and Mendeleev basins. The study provides data on the structure of the Chukchi Borderland and the surrounding geological structures, morphology and geology, uses bathymetric materials, seismic materials from CDP and deep seismic survey, sampling and drilling data. A review of materials on the study region was carried out. The latest results of geomorphological analysis of bathymetric data and 3D modeling of the Earth’s crust of the study region using geophysical data are presented. To explain the identified features of the morphology and deep structure of the Chukchi Borderland, a tectonic model is proposed that explains the deep mechanisms of its formation and adjacent structures, as well as a structural-tectonic scheme of the Arctic Alaska–Chukotka microplate, which presents the morphological and geological connection of the Chukchi Borderland with the continental shelf.
{"title":"Tectonic Model of the Formation of the Chukchi Borderland","authors":"V. A. Poselov, A. S. Zholondz, O. E. Smirnov, A. L. Piskarev, S. M. Zholondz, V. A. Savin, A. G. Zinchenko, N. E. Leonova, A. A. Kireev","doi":"10.1134/s0016852123070117","DOIUrl":"https://doi.org/10.1134/s0016852123070117","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">\u0000<b>Abstract</b>—</h3><p>The Chukchi Borderland is a tectonic unit of the eastern part of the Arctic continental margin of Eurasia that is part of the complex of the Central Arctic rises, along with the Lomonosov Ridge, the Alpha‒Mendeleev Rise, the Podvodnikov, Chukchi and Mendeleev basins. The study provides data on the structure of the Chukchi Borderland and the surrounding geological structures, morphology and geology, uses bathymetric materials, seismic materials from CDP and deep seismic survey, sampling and drilling data. A review of materials on the study region was carried out. The latest results of geomorphological analysis of bathymetric data and 3D modeling of the Earth’s crust of the study region using geophysical data are presented. To explain the identified features of the morphology and deep structure of the Chukchi Borderland, a tectonic model is proposed that explains the deep mechanisms of its formation and adjacent structures, as well as a structural-tectonic scheme of the Arctic Alaska–Chukotka microplate, which presents the morphological and geological connection of the Chukchi Borderland with the continental shelf.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"79 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097532","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1134/s0016852123070063
D. V. Elkina, A. L. Piskarev, D. V. Bezumov
Abstract—
The age assignment to the Arctic Basin sediments is complicated by the insufficient microfauna in them. Under these conditions, the paleomagnetic method is the major method to determine age boundaries. This method was used to construct the first successful age model of Arctic sediments in the 1970s. In recent decades, a number of works made it possible to describe changes in natural remanent magnetization direction as a consequence of secondary geochemical processes, in fact, discrediting the possibility of applying paleomagnetism to the Arctic Basin sediments. Based on our research of natural remanent magnetization in sediment cores from the Central Arctic submarine elevations, the reference paleomagnetic horizons were determined reliably. The sedimentation rates at the Alpha and Mendeleev ridges was calculated to be low (<2 mm/kyr). Mean sedimentation rates increase toward the Lomonosov Ridge due to the influence of the Transpolar Drift and toward the shelf. Based on the comprehensive analysis of the paleomagnetic and seismoacoustic data, low sedimentation rates have been characteristic of the Mendeleev Ridge and Podvodnikov Basin since the Early Miocene.
{"title":"Sedimentation in the Central Arctic Submarine Elevations: Results of Comprehensive Analysis of Paleomagnetic and Seismoacoustic Data","authors":"D. V. Elkina, A. L. Piskarev, D. V. Bezumov","doi":"10.1134/s0016852123070063","DOIUrl":"https://doi.org/10.1134/s0016852123070063","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">\u0000<b>Abstract</b>—</h3><p>The age assignment to the Arctic Basin sediments is complicated by the insufficient microfauna in them. Under these conditions, the paleomagnetic method is the major method to determine age boundaries. This method was used to construct the first successful age model of Arctic sediments in the 1970s. In recent decades, a number of works made it possible to describe changes in natural remanent magnetization direction as a consequence of secondary geochemical processes, in fact, discrediting the possibility of applying paleomagnetism to the Arctic Basin sediments. Based on our research of natural remanent magnetization in sediment cores from the Central Arctic submarine elevations, the reference paleomagnetic horizons were determined reliably. The sedimentation rates at the Alpha and Mendeleev ridges was calculated to be low (<2 mm/kyr). Mean sedimentation rates increase toward the Lomonosov Ridge due to the influence of the Transpolar Drift and toward the shelf. Based on the comprehensive analysis of the paleomagnetic and seismoacoustic data, low sedimentation rates have been characteristic of the Mendeleev Ridge and Podvodnikov Basin since the Early Miocene.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"67 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1134/s0016852123070105
A. L. Piskarev, V. D. Kaminsky, A. A. Kireev, V. A. Poselov, V. A. Savin, O. E. Smirnov, D. V. Bezumov, E. A. Dergileva, D. V. Elkina, G. I. Ovanesian, E. S. Ovsiannikova
Abstract
In 2011‒2020 a significant number of seismic lines were carried out in the Eurasian Basin of the Arctic Ocean, which made it possible to study the structure of the junction zones of the Gakkel Ridge with the Nansen and Amundsen basins on a number of profiles. During 2019‒2020 15 sections of the Gakkel Ridge and its rift valley were studied using a sub-bottom profiler and seismo-acoustic profiling. New data on the relief of the basement, as well as the use of databases of bathymetry, gravity, and magnetic anomalies updated at VNIIOkeangeologia, made it possible to calculate the magnetization of the rocks of the Gakkel Ridge along a number of profiles crossing the ridge and to perform model calculations of the structure of the Earth’s crust using a complex of geological and geophysical data in the area of the southeastern termination of the ridge. The Gakkel Ridge is a structure that was isolated in the Early Oligocene (34 Ma)–Early Miocene (23 Ma) in the process of radical restructuring of the spreading kinematics in the existing ocean basins in the regions of the North Atlantic and the Arctic. The values of the calculated magnetization of the magnetic layer of the Earth’s crust show that this layer is partly composed of oceanic basalts, but mainly of deep-originated rocks, gabbro, and peridotites that were brought to the surface during detachment accompanying spreading. The Laptev Sea continuation of the rift valley of the Gakkel Ridge to the south of the caldera passes above many kilometers of sediments, at the base of which sedimentary rocks of Cretaceous and Late Jurassic age occur.
{"title":"The Structure of the Gakkel Ridge: Geological and Geophysical Data","authors":"A. L. Piskarev, V. D. Kaminsky, A. A. Kireev, V. A. Poselov, V. A. Savin, O. E. Smirnov, D. V. Bezumov, E. A. Dergileva, D. V. Elkina, G. I. Ovanesian, E. S. Ovsiannikova","doi":"10.1134/s0016852123070105","DOIUrl":"https://doi.org/10.1134/s0016852123070105","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>In 2011‒2020 a significant number of seismic lines were carried out in the Eurasian Basin of the Arctic Ocean, which made it possible to study the structure of the junction zones of the Gakkel Ridge with the Nansen and Amundsen basins on a number of profiles. During 2019‒2020 15 sections of the Gakkel Ridge and its rift valley were studied using a sub-bottom profiler and seismo-acoustic profiling. New data on the relief of the basement, as well as the use of databases of bathymetry, gravity, and magnetic anomalies updated at VNIIOkeangeologia, made it possible to calculate the magnetization of the rocks of the Gakkel Ridge along a number of profiles crossing the ridge and to perform model calculations of the structure of the Earth’s crust using a complex of geological and geophysical data in the area of the southeastern termination of the ridge. The Gakkel Ridge is a structure that was isolated in the Early Oligocene (34 Ma)–Early Miocene (23 Ma) in the process of radical restructuring of the spreading kinematics in the existing ocean basins in the regions of the North Atlantic and the Arctic. The values of the calculated magnetization of the magnetic layer of the Earth’s crust show that this layer is partly composed of oceanic basalts, but mainly of deep-originated rocks, gabbro, and peridotites that were brought to the surface during detachment accompanying spreading. The Laptev Sea continuation of the rift valley of the Gakkel Ridge to the south of the caldera passes above many kilometers of sediments, at the base of which sedimentary rocks of Cretaceous and Late Jurassic age occur.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"2015 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097607","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-03-10DOI: 10.1134/s0016852123070026
A. V. Bochkarev, Yu. Yu. Smirnov, T. V. Matveeva
Abstract
Regional-scale geothermal maps are the basis for calculations and mapping of the thermobaric stability zone of submarine gas hydrates. Global geothermal measurements (in particular, at the Eurasian continental margin of the Arctic Ocean) are sporadic. The lack of geotemperature data does not allow mapping of thermal fields using standard interpolation methods. This article presents a solution to this problem and the results of geothermal mapping of the Eurasian continental margin of the Arctic Ocean by extrapolation on a structural-tectonic basis following the age of tectonomagmatic activation of geological structures. The TEMAR-10 000 tectonic map of the Arctic was chosen as a structural-tectonic basis for zoning by age of tectonomagmatic activation. The geothermal studies were based on verified data from the Global Heat Flow Database, as well as published materials and the authors’ original data. A geothermal database consisting of ~1000 geotemperature estimates has been compiled. Verification and statistical analysis of geothermal data in the Eurasian margin of the Arctic Ocean was performed. It has been established that the median values of heat flow are the most applicable for geothermal zoning on a structural-tectonic basis. The geothermal zoning of the Laptev Sea has been clarified based on seismic survey data on the position of the hydrate-related reflector, marking the phase boundary of the gas hydrate stability zone. For the first time, regional-scale geothermal mapping has been carried out at the Eurasian continental margin using actual measured and calculated geothermal data. The compiled geothermal map is the basis for calculating and mapping the gas hydrate stability zone.
{"title":"Heat Flow at the Eurasian Margin: A Case Study for Estimation of Gas Hydrate Stability","authors":"A. V. Bochkarev, Yu. Yu. Smirnov, T. V. Matveeva","doi":"10.1134/s0016852123070026","DOIUrl":"https://doi.org/10.1134/s0016852123070026","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3><p>Regional-scale geothermal maps are the basis for calculations and mapping of the thermobaric stability zone of submarine gas hydrates. Global geothermal measurements (in particular, at the Eurasian continental margin of the Arctic Ocean) are sporadic. The lack of geotemperature data does not allow mapping of thermal fields using standard interpolation methods. This article presents a solution to this problem and the results of geothermal mapping of the Eurasian continental margin of the Arctic Ocean by extrapolation on a structural-tectonic basis following the age of tectonomagmatic activation of geological structures. The TEMAR-10 000 tectonic map of the Arctic was chosen as a structural-tectonic basis for zoning by age of tectonomagmatic activation. The geothermal studies were based on verified data from the Global Heat Flow Database, as well as published materials and the authors’ original data. A geothermal database consisting of ~1000 geotemperature estimates has been compiled. Verification and statistical analysis of geothermal data in the Eurasian margin of the Arctic Ocean was performed. It has been established that the median values of heat flow are the most applicable for geothermal zoning on a structural-tectonic basis. The geothermal zoning of the Laptev Sea has been clarified based on seismic survey data on the position of the hydrate-related reflector, marking the phase boundary of the gas hydrate stability zone. For the first time, regional-scale geothermal mapping has been carried out at the Eurasian continental margin using actual measured and calculated geothermal data. The compiled geothermal map is the basis for calculating and mapping the gas hydrate stability zone.</p>","PeriodicalId":55097,"journal":{"name":"Geotectonics","volume":"105 1","pages":""},"PeriodicalIF":1.1,"publicationDate":"2024-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140097276","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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