scholarly journals Stratigraphic basement and correlation of the precambrian central part cuts of the Ukrainian shield

2020 ◽  
pp. 11-16
Author(s):  
M. M. Kostenko
Keyword(s):  
Suture Zone ◽  
Ukrainian Shield ◽  
Structural Elements ◽  
The West ◽  
Early Precambrian ◽  
Carbonate Carbon

In the central part of the Ukrainian Shield are allocated two independent structural elements: Inhul block and Inhulets-Kryvyi Rih suture zone, instead of the Inhul-Inhulets region, according to the current tectonic zoning in “Correlation Chronostratigraphic Scheme of the Early Precambrian of the Ukrainian Shield”. The stratigraphic dividing of this territory has not undergone any changes. The article suggests existing Inhul-Inhulets Series in this scheme to divided into two: the Inhul (Inhul block) and the Inhulets (Inhulets-Kryvyi Rih suture zone) and several independent strattons in the Suites rank. As part of the Inhul Series, the upper part of the Inhul-Inhulets Series remains as part of the Kamianokostuvatska and Roshсhakhivska (Bratskа SFZ) and Spasivska and Checheliivska (Inhul SFZ) Suites. In the lower part of the section, there is an independent Rodionivska Suite. The West Inhulets and Kryvyi Rih-Kremenchuk SFZ stratigraphic sections of the Inhulets-Kryvyi Rih suture zone are identical and completely correlate with each other: lower Mesoarchean metaterigenic Lativska Suite is basal for both, Mesoarchean metavolcanogenic Nyzhnozelenorichanska Suite of the West-Inhulets SFZ is correlated with the Novokryvorizka Suite of the Kryvyi Rih-Kremenchuk SFZ, Paleoproterozoic Inhulez Series – respectively, with the Kryvyi Rih Series (metavolcanogenic-sedimentary Verkhnozelenorichanska Suite – with the Skeliuvatska Suite, and the metaterigenic-ferrous Artemivska Suite – with the Saksaganska), carbonate-carbon-terigenic Rodionivska Suite – with Hdantsivska. These stratigraphic units represent by themselves their own suture formations of the Inhulets-Kryvyi Rih suture zone.

scholarly journals Revisiting stratigraphic complexes and regional stratigraphic scheme of the lower precambrian of the Ukrainian shield

2019 ◽  
pp. 40-48
Author(s):  
V. P. Kyrylyuk
Keyword(s):  
Material Composition ◽  
Ukrainian Shield ◽  
Historical Period ◽  
The West ◽  
Isotopic Dating ◽  
Early Precambrian ◽  
Stratigraphic Unit ◽  
Leading Role ◽  
Tectonic Position

The stratigraphic scheme of the Early Precambrian of the Ukrainian Shield bears a number of differences from the traditional regional stratigraphic schemes: 1) along with stratified subdivisions it includes intrusive and ultrametamorphic complexes that are not accounted for in the “Stratigraphic Code of Ukraine”; 2) The leading role in creating the regional stratigraphic scheme was played by isotopic dating results; 3) The Stratigraphic Scheme does not include the taxon “complex”, as it is described in the “Stratigraphic Code of Ukraine”. According to “Stratigraphic Code of Ukraine”, “Complex” is the largest regional stratigraphic unit that corresponds to a large geo-historical period. Due to the absence of the taxon of “complex” in the regional Precambrian stratigraphic scheme, the main stages of geological development of the region in the Precambrian have not been identified for the Ukrainian Shield. The first article of the cycle is devoted to the feasibility of introducing the taxon of “complex” in the regional stratigraphic scheme on the materials of the Ukrainian Shield. It notes that most of the series in the current stratigraphic scheme correspond to complexes by their level of study and their historical and geological content. Such units are Konkska, Kryvorizka, Teterivska, Ingulo-Inguletska and some other series. Each of them can be separated into several series. The Dniestrovsko-Bugska and Bugska series, the West-Priazovska and Central-Priazovska series of granulite-gneiss complexes are artificially separated and shown as different age subdivisions in the current stratigraphic scheme. These series should be included in the Bug Area and Azov Area complexes, but their volumes and names need clarification. Amphibolite-gneiss complexes can be included in the stratigraphic scheme without dismemberment into series, since they correspond to a large geohistoric stage marked by the peculiarities of their material composition and structural-tectonic position.

A Model of Seawater Structure Near the West Coast of Vancouver Island, British Columbia

1963 ◽  
Vol 20 (4) ◽  
pp. 939-967 ◽  
Author(s):  
Robert K. Lane
Keyword(s):  
British Columbia ◽  
West Coast ◽  
Large Scale ◽  
Coastal Region ◽  
Vancouver Island ◽  
Structural Elements ◽  
The West ◽  
Characteristic Structure ◽  
Oceanographic Data ◽  
Vertical Sections

Oceanographic data collected in a line of stations extending seaward of the west coast of Vancouver Island, British Columbia, were reviewed and analyzed. On the basis of these data and the large-scale meteorological processes of wind, insolation, and precipitation, the characteristic structure of temperature and salinity in the coastal region was denned in five temporal stages throughout the year. These stages are presented as vertical sections along the line with characteristic ranges of values to be found in each of the structural elements.

scholarly journals Upper mantle structure around the Trans-European Suture Zone obtained by teleseismic tomography

2014 ◽  
Vol 6 (2) ◽  
pp. 1723-1763 ◽  
Author(s):  
I. Janutyte ◽  
M. Majdanski ◽  
P. H. Voss ◽  
E. Kozlovskaya ◽  
PASSEQ Working Group
Keyword(s):  
Upper Mantle ◽  
Western Europe ◽  
Velocity Model ◽  
Suture Zone ◽  
P Wave ◽  
Mantle Structure ◽  
The West ◽  
Lower Velocity ◽  
Teleseismic Tomography ◽  
Upper Mantle Structure

Abstract. The presented study aims to resolve the upper mantle structure around the Trans-European Suture Zone (TESZ) which is the major tectonic boundary in Europe. The data of 183 temporary and permanent seismic stations operated during the period of the PASsive Seismic Experiment PASSEQ 2006–2008 within the study area from Germany to Lithuania was used to compile the dataset of manually picked 6008 top quality arrivals of P waves from teleseismic earthquakes. We used the non-linear teleseismic tomography algorithm TELINV to perform the inversions. As a result, we obtain a model of P wave velocity variations up to about ±3% compared to the IASP91 velocity model in the upper mantle around the TESZ. The higher velocities to the east of the TESZ correspond to the older East European Craton (EEC), while the lower velocities to the west of the TESZ correspond to younger Western Europe. We find that the seismic lithosphere-asthenosphere boundary (LAB) is more distinct beneath the Phanerozoic part of Europe than beneath the Precambrian part. To the west of the TESZ beneath the eastern part of the Bohemian Massif, the Sudetes Mountains and the Eger Rift the negative anomalies are observed from the depth of at least 70 km, while under the Variscides the average depth of the seismic LAB is about 100 km. We do not observe the seismic LAB beneath the EEC, but beneath Lithuania we find the thickest lithosphere of about 300 km or more. Beneath the TESZ the asthenosphere is at a depth of 150–180 km, which is an intermediate value between that of the EEC and Western Europe. The results imply that the seismic LAB in the northern part of the TESZ is of a shape of a ramp dipping to the NE direction. In the southern part of the TESZ the LAB is shallower, most probably due to younger tectonic settings. In the northern part of the TESZ we do not recognize any clear contact between Phanerozoic and Proterozoic Europe, but further to the south we may refer to a sharp and steep contact on the eastern edge of the TESZ. Moreover, beneath Lithuania at the depth of 120–150 km we observe the lower velocity area following the boundary of the proposed palaeosubduction zone.

scholarly journals 40Ar/39Ar age of rock deformations across the Bazhenov suture zone (eastern border of the Middle Urals)

LITOSFERA ◽  
2019 ◽  
pp. 242-249
Author(s):  
V. N. Smirnov ◽  
K. S. Ivanov ◽  
A. V. Travin
Keyword(s):  
Strike Slip ◽  
Suture Zone ◽  
Age Dating ◽  
Middle Urals ◽  
The Urals ◽  
The West ◽  
The Middle Urals ◽  
Deformation Processes ◽  
Eastern Border ◽  
Rock Deformations

Research subject. This article presents data on the nature of rock deformations in the Bazhenov suture zone. The data was obtained by 40Ar/39Ar dating of mica samples from schists and blastomylonites, which were collected acrossan area extending approximately for 100 km along the Bazhenov suture. This suture separates the Eastern zone of the Middle Urals dipped under the cover of the West Siberian plate from exposed geologic structures of the Urals.Methods.The character of the deformations was studied by means of direct geological observation. The age of the deformations was determined by mica dating using the 40Ar/39Ar method.Results. The deformations were found to have occurred in several phases. The initial phase, which led to the formation of a band of blastomylonites and rocks showing a varying degree of schistosity with a width of over 10 km in particular areas, is likely to have had the character of left-lateral fault. The upper age limit of this deformation phase is determined by the intrusion of the subalkaline rocks of the Petukhovskii complex (280 Ma), which had not been affected by any deformation processes. The subsequent type of deformations had been left-lateral strike-slip faults of submeridianal strike and subvertical dip, which were represented by low-thickness (usually about 10 cm, rarely up to 0.5 m) zones of intensely deformed rocks cutting the schistosity of the previous phase at an acute angle. The final phase of the deformations is shown to be a sloping fault. The dislocation planes of this type were represented by slickensides and chlorite incrustations. Despite the apparent polychronicity of the deformation processes, which were established within the Bazhenov suture zone by our geological observations, 40Ar/39Ar age dating identified only one event. The average value of five conducted tests was about 251 Ma. Apparently, this age should be associated with the most recent geological processes having occurred at temperatures sufficient to fully overload the K-Ar isotopic system of the studied rocks, such as the deformations caused by strike-slip dislocations.Conclusions. The strike-slip fault dislocations dated in this work occurred approximately 25 Ma after the completion of the tectonic activity in the Serov-Mauk fault zone, which is located to the west of the Bazhenov zone. In addition, the time of these dislocations very nearly coincides with that of the formation of the grabens of meridional strike at the base of the West Siberian plate, which took place about 250 Ma ago. This supports apreviously made conclusionon the similar character of the geological development of the eastern border part of the Urals and the adjoining basement of the West Siberian plate. 

scholarly journals On the specification of the chronostratigraphic scheme of the Buzko-Rosynskyi block of the Ukrainian Shield

2020 ◽  
pp. 20-23
Author(s):  
V. P. Bezvynnyi ◽  
M. M. Kostenko
Keyword(s):  
Iron Ore ◽  
Magnetic Anomalies ◽  
Amphibolite Facies ◽  
Ukrainian Shield ◽  
Crystalline Schist ◽  
Stratigraphic Sequence ◽  
Early Precambrian ◽  
Current Correlation ◽  
Low Probability ◽  
Local Temperature Increase

In the current correlation chronostratigraphic scheme of early Precambrian of the Ukrainian Shield, among Neoarchean supra crystalline formations of the Buzko-Rosynskyi block, it is identified the Rosynsko-Tikytska series, which consist of the Myzynivska and Lysianska strata and the independent Volodarsko-Bilotserkivska strata, which are located on the same stratigraphic level in the scheme. According to the results of the mapping of metamorphic formations within this block during the geological survey of scale 1:200 000 (articles “Bila Tserkva”, “Uman”, “Lyubashivka”, “Kotovsk”, “Haisyn”, “Skvyra”) it is established these stratas are located in the section in a following order: the lower one is the Myzynivska, the middle one is the Volodarsko-Bilotserkivska and the upper one is the Lysianska and they form a single Rosynsko-Tikytska series. Also, these works did not confirm the presence in the region of the Bilotserkivska group of magnetic anomalies of two-pyroxene schale among the rocks of the Volodarsko-Bilotserkivska strata. This is a sign of their higher metamorphism degree. The hypersthene is present in the area of the Volodarka then only in high-iron rocks. Its presence is associated with a local temperature increase during metamorphism due to the high oxidative ability of iron. This indicates the possibility of its crystallization under conditions of amphibolite facies. A powerful argument in favor of this is the occurrence of a relatively thin carbonate-ferruginous-siliceous strata among thick amphibolite-gneiss and crystalline-schist-amphibolite strata which metamorphosed under amphibolite facies conditions. It indicates the low probability that the metamorphism of the iron ore could occur locally in other conditions. The obtained new data on the composition of the Rosynsko-Tikytska series and the actual stratigraphic sequence of stratas in it, indicates the necessity of making appropriate changes in the current correlation chronostratigraphic scheme of early Precambrian formations of the Ukrainian Shield.

scholarly journals TECTONIC EVOLUTION OF THE WEST-PACIFIC REGION: FORMATION OF LITHOSPHERIC VORTEXES

2021 ◽  
Vol 24 (1) ◽  
pp. 10-25
Author(s):  
L.A. Izosov ◽  
Yu.I. Melnichenko ◽  
V.I. Chuprynin ◽  
N.S. Lee ◽  
B.A. Kasanskiy ◽  
...  
Keyword(s):  
Tectonic Evolution ◽  
Pacific Region ◽  
Structural Elements ◽  
The West ◽  
West Pacific ◽  
The Earth ◽  
Lineament Analysis ◽  
Tectonic Dislocations ◽  
Convective Cells ◽  
The Western Pacific

Using the example of the West Pacific Segment of the Earth, the interrelation of vertical and horizontal tectonic movements is considered – the most important and far from being solved at present problem of geotectonics. An overview of the concept of the global ordering of various forms of the earth's surface as an end result of the action of geodynamic forces is given. The author's developments concern the issues of the origin of structures associated with the interaction and influence of endogenous forces on the formation of a regional relief. The main tools for its study were structural-geomorphological methods and lineament analysis. It has been established that: 1) all tectonic dislocations contain both horizontal and vertical components of the velocity of movement, and the former dominate in the structure formation of the region; 2) the end result of their interaction is vortex and other nonlinear (ring, spiral, arc, etc.) deformations of the lithosphere, which constitute the main type of structural elements of the region; 3) they are often accompanied by magmatic activation of the tectonosphere in the form of convective movements and / or «floating» of plumes; 4) the sea and oceanic depressions of the Western Pacific are, in essence, funnels of convective cells, which, under the conditions of shear velocities of the movement of interacting geoblocks of the lithosphere, were structured into the form of tectonospheric eddies. A model of convection of a three-layer tectonosphere is proposed, the movement of which in the gravity field is caused by local decompaction and a decrease in the viscosity of a piecewise inhomogeneous medium. The outlined concepts allow us to consider the tectonic evolution of the West Pacific region as the formation of a lithospheric mega-vortex in the continent-ocean junction zone. Its development is associated with the energy interaction of the mantle and the upper shells (tectonospheres) of the Earth, which is due to the unstable regime of the planet's rotational dynamics.

scholarly journals THE PALEOARCHEAN (3.3 Ga) AND MESOARCHEAN (3.0 Ga) TTGs OF THE WESTERN AZOV AREA, THE UKRAINIAN SHIELD

2021 ◽  
pp. 35-47
Author(s):  
G.V. Artemenko ◽  
L.V. Shumlyanskyy
Keyword(s):  
Chemical Composition ◽  
Detrital Zircons ◽  
Geochemical Characteristics ◽  
Ukrainian Shield ◽  
Metamorphic Rocks ◽  
The West ◽  
Siliceous Rocks ◽  
Zircon Crystallization ◽  
Greenstone Belts ◽  
Archean Greenstone Belts

A large anticline structure that includes the West Azov and Remivka blocks occurs in the western part of the Azov Domain of the Ukrainian Shield. These blocks are composed of rocks of the Mesoarchean (3.2-3.0 Ga) granite-greenstone association and relics of an older basement. The anticline is divided into two parts by the Bilotserkivka structure of sub-latitudinal strike; the northern part includes the Huliaipole and Remivka blocks, and the southern part is comprised of the Saltycha anticline. The Archean plagiogranitoids of the West Azov underwent intense dislocation metamorphism during the Paleoproterozoic. In many areas they were transformed into plagioclase gneisses that were attributed to the Paleoarchean “Kainkulak thickness” of the Azov Series. Detailed geological-structural and geochronological studies are required to define the age of these gneisses.We have chosen two areas for our studies: the Lantsevo anticline within the Bilotserkivka structure, and the Ivanivka area in the eastern part of the Saltycha anticline. The Bilotserkivka structure is composed of rocks of the Central Azov Series and highly deformed Archean formations. We have dated plagiogneisses of the Lantsevo anticline. These rocks contain large relics of metamorphic rocks of unknown age, including two-pyroxene and pyroxene crystalline schists, and pyroxenemagnetite quartzites (BIF). In terms of chemical composition, two-pyroxene crystalline schists correspond to tholeiitic basalts and basaltic komatiites. Ferruginous-siliceous rocks belong to the Algoma type typical for the Archean greenstone belts. Biotite gneisses are similar to the medium-pressure tonalite-trondhjemite-granodiorite rocks (TTGs). The U-Pb age of zircon crystallization from biotite gneisses is 3299 ± 11 Ma. At 30 km in the western part of the Bilotserkivka structure, we have previously identified quartz diorites having an age of 3297 ± 22 Ma. In terms of geochemical characteristics, they correspond to low-pressure TTGs. These data show that the Bilotserkivka structure is a block representing an ancient basement. In the Ivanivka area in the eastern part of the Saltycha anticline, the strike of the Archean rocks was reorientated from northwestern to latitudinal. The studied dislocated trondhjemites of the Ivanivka area correspond to TTGs in terms of the geochemical characteristics. They contain numerous relics of highly altered amphibolites. The U-Pb age of zircon crystallization from trondhjemite is 3013 ± 15 Ma. These rocks are of the same age as TTGs of the Shevchenko Complex cutting through the sedimentary-volcanogenic rocks of the greenstone structures of the Azov Domain. They share age and geochemical characteristics with biotite and amphibole-biotite gneisses of the “Kainkulak thickness” in Zrazkove village located at the Mokra Konka river (3.1-3.0 Ga) and with biotite gneisses in the lower reaches of the Kainkulak river (2.92 Ga). Thus, gneisses of the “Kainkulak thickness” in fact represent the Mesoarchean TTGs of the Shevchenko Complex, which were transformed in the Paleoproterozoic time due to the dislocation metamorphism. Late Paleoarchean (3.3 Ga) tonalites are known in the West Azov and the KMA domains; they probably also occur in the basement of the Middle Dnieper domains, where detrital zircons of this age have been reported. These data allow us to conclude the existence of a large Late Paleoarchean (3.3 Ga) protocraton, in which the Mesoarchean (3.2-3.0 Ga) greenstone belts and TTGs of the eastern part of the Ukrainian Shield and the KMA Domain were formed.

scholarly journals The Upper Triassic deposits of the west Bangong-Nujiang suture zone and their paleogeographic implications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guichun Wu ◽  
Zhansheng Ji ◽  
Gary G. Lash ◽  
Jianxin Yao
Keyword(s):  
Central Region ◽  
Upper Triassic ◽  
Suture Zone ◽  
Late Triassic ◽  
Upper Permian ◽  
The West ◽  
Apparent Lack ◽  
Sedimentary Succession ◽  
Depositional Setting ◽  
Qiangtang Terrane

AbstractThe Bangong-Nujiang Suture Zone (BNSZ) of Tibet (Xizang) has been interpreted to represent a relic of the Bangong-Nujiang Ocean. However, the existence of this ocean during Triassic time remains a point of contention. A sedimentary succession spanning the Upper Permian through Triassic described from the central BNSZ suggests that the Lhasa and South Qiangtang terranes were contiguous thus negating the existence of a terrane-separating ocean during Triassic time. However, the apparent lack of Triassic deposits in the west BNSZ has called into question the existence of Triassic deposits in the central region of the BNSZ. Our biostratigraphic work in the Wuga Formation of the Gaize area has yielded abundant Norian conodonts thus confirming the existence of Upper Triassic deposits in the west BNSZ. The clastic deposits of the Wuga Formation are herein interpreted to be of Rhaetian age. Moreover, intercalated limestone and chert are termed the Dongnale Formation of Norian age. The Norian to Rhaetian succession can be correlated with strata of the central BNSZ as well as with deposits of the Lhasa Terrane and the South Qiangtang Terrane. Similar stratigraphies among these regions through the Late Triassic suggests a shared depositional setting and that the BNSZ was not an ocean in Norian and Rhaetian time.

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