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":null,"pages":null},"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":null,"pages":null},"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":null,"pages":null},"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
Abstract
The Khangai plume is situated under Central and Eastern Mongolia and is a mantle volume with significantly reduced longitudinal (P) wave velocities. The plume has been identified as a result of the analysis of the MITP08 volumetric model of P-wave velocity variations, representing the deviations of P-wave velocities from the average values (δVp), given as a percentage. The lithospheric mantle is thinned to ca. 50 km above the plume. Especially low velocities (δVp ≤ –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":null,"pages":null},"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}