scholarly journals Uranium-Lead by Monacite Geochronology of Granites Distributed in the Middle Current of ihe River Ros (Ros-Tikich Megablock Ukrainian Shield)

2021 ◽  
pp. 89-93
Author(s):  
Т.I. Dovbush ◽  
◽  
L.M. Stepaniuk ◽  
О.V. Ziultsle ◽  
Т.B. Yaskevych ◽  
...  
Keyword(s):  
Geological Structure ◽  
Ukrainian Shield ◽  
Isotopic Age ◽  
Isotopic Dating ◽  
Leading Role ◽  
The Village ◽  
Good Agreement

Granitoids play a leading role in the geological structure of the Ros-Tikich megablock. The rocks of the Ros-Tikich series, which form the supercrystalline base here, have survived among the granitoids only in the form of some remnants of different sizes. In the coastal outcrops of the middle course of the river Ros (east of Bila Tserkva) and in the quarries located near the river, the most common are two-feldspar granitoids, isolated as part of two complexes – Uman and Stavyshche. Plagiogranitoids and supercrustal rocks have survived among them in the form of separate fragments. Of the accessory uranium-containing minerals, zircon and titanite are present in two-field spar granites, and monazite was found in single samples of granites in which titanite was absent. The age of obscure porphyry-like granite discovered by the Ostrivsk quarry – 2063.5 ± 1.2 million years and uniformgrained granite, distributed in the quarry of the village of Bovkun – 2042.5 ± 8.6 million years. The obtained values of the isotopic age of these granites are in good agreement with the results of uranium-lead isotopic dating of zircons from twofeldspar granites of the Ros-Tikich megablock (1990-2080 million years). This allows us to propose to combine the granites of the Stavyshche and Uman complexes into one Paleoproterozoic complex.

scholarly journals Uranium-Lead Geochronology on Monacite of Granites of the Lypnyazka Massif and its Framing (Ingul Megablock of the Ukrainian Shield)

2021 ◽  
pp. 71-79
Author(s):  
L.M. Stepanyuk ◽  
◽  
S.I. Kurylo ◽  
V.O. Syomka ◽  
T.I. Dovbush ◽  
...  
Keyword(s):  
Isotopic Composition ◽  
Ukrainian Shield ◽  
Upper Crust ◽  
Isotopic Dating ◽  
Granite Massif ◽  
Rare Elements ◽  
The Village

The Lipnyazka massif is located in the Dobrovelychkivsky district of the Kirovohrad region, v. Lipnyazka and further south. Structurally, it is located within the Bratskyy Synclinorium of the Ingul megablock and coincides with the Mikhailovsky anticline. The main petrotype of the massif rocks are porphyry-like granites, often with a gneiss-like texture, aplito-pegmatoid, pegmatoid granites and pegmatites. The latter most often form secant vein bodies. Uranium-lead isotopic dating of granitoids of the Lipnyazka granite massif has been performed, with which a number of deposits and ore occurrences of rare elements, primarily lithium, are spatially and probably genetically connected. The age of porphyry-like granites (2032 ± 6 million years), which is the main petrotype of rocks distributed in the area of the village of Limestone and pegmatoid granites (2027 ± 1 million years), which cut porphyry-like in the form of vein bodies. Aplithoid framed granites (2046 ± 8 million years old), common in the area of the mouth of the Sukhyi Tashlyk River (Dobryanka village), are somewhat older. Based on the results of determining the isotopic composition of strontium in the accessory apatite of granites, a conclusion was made about the upper crust source of granites of the Lipnyazka massif (87Sr/86Sr – 0.730-0.785).

scholarly journals Geological features and the first isotopic data of volcanic rocks in the Iset river basin, East-Urals megazone

2021 ◽  
Vol 1 ◽  
pp. 55-64
Author(s):  
Vasiliy Stanislavovich CHERVYAKOVSKIY
Keyword(s):  
River Basin ◽  
Large Scale ◽  
Volcanic Rocks ◽  
Early Carboniferous ◽  
Geological Structure ◽  
Geological Mapping ◽  
Isotopic Age ◽  
Isotopic Dating ◽  
Sedimentary Deposits ◽  
Tectonic Contact

Relevance of the work. The Iset river basin contains the most extensive outcrops of volcanogenic formations of the Beklenishchevsky complex of the East Ural megazone, the age of which is determined as Early Carboniferous by the ratio of volcanic rocks with faunistically characterized sedimentary deposits. Volcanics here compose flows of andesite-basaltic and andesitic lavas and lava breccias. There are no geochronological dates specifying the age of the rocks, which makes it difficult to assess their role in the formation of the megazone. Therefore, isotopic dating of these formations is very important. Methods. The U – Pb age and data on the geochemistry of zircons were obtained by laser ablation (LA – ICP – MS). Purpose of the research is to study the features of the geological structure, the material composition of volcanic rocks in the Iset river basin, the geochemistry of zircons from andesites and the determination of their isotopic age. Results of the work and the scope of their application. Lava flows of andesites and basaltic andesites with minor amounts of basalts and dacites have tectonic contact with sedimentary rocks of the Early Carboniferous age. The distribution of rare elements in volcanics is typical of supra-subduction formations. Zircons in andesites are represented by prismatic and isometric crystals. Prismatic differences in the nature of the distribution of REE and the content of Li, Ti, Sr, Th, U refer to zircons of magmatic genesis, isometric – to “hydrothermal”. According to the U / Yb – Y ratios, the former correspond to the zircons of the ocean floor, while the latter are related to the continental ones. Isotopic dating of zircons from andesites was carried out for the first time. Their age was 311 million years. The data can be used in geological mapping, as well as in the compilation of large-scale geodynamic maps and diagrams. Conclusions. Volcanic rocks in the Iset river basin were formed in supra-subduction continental-marginal geodynamic conditions that took place in the Urals in the Carboniferous. The obtained value of the age of zircons from andesites, possibly, fixes the stage of their transformation. Keywords: East-Ural megazone, volcanic rocks, zircon, isotopic age.

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.

scholarly journals Uranium-thorium mineralization process of the Ukrainian shield suture zones and evolution of the composition of depth fluids in Precambrian

2020 ◽  
pp. 45-53
Author(s):  
O.V. Usenko ◽  
Keyword(s):  
Geological Structure ◽  
Complex Compounds ◽  
Ukrainian Shield ◽  
Mineralization Process ◽  
Chloride Complexes ◽  
Geochemical Properties ◽  
Carbonate Ions ◽  
Uranyl Carbonate ◽  
Group Reduction ◽  
Acid Reaction

Тhe geochemical properties of uranium and thorium and the geological structure of the ore oc currences of the Golovanevskaya and Ingulo-Inguletskaya suture zones are correlated with changes in the composition of mantle melts and fluids in the Archean-Paleoproterozoic. It is shown that the formation of uranium and thorium deposits on the Ukrainian shield became possible in the Proterozoic, when oxidized and acidic melts prevailing in the Archean mantle were replaced by neutral and alkaline water-chloride-potassium. This led to the accumulation of tho rium (to a greater extent) and uranium (to a less extent) in granite magmas of the layer of partial melting of the crust, where they entered as chloride complexes. The ore occurrences of monazite in microcline granites and pegmatites of the Berdichev and Kirovograd complexes formed in the period 2.1-1.9 billion years ago are associated with these processes. The enrichment of crustal centers of melting with uranium occurred most intensively after 2.0 billion years ago (a maximum of 1.8-1.65 billion years ago), when uranyl-carbonate ions entered the crust as a part of mantle carbonate-fluoride-sodium fluids, they were mixed with melts of existing melting centers. A change in the pH of the medium led to the decomposition of complex compounds and the release of the uranyl group, reduction of uranium to U4+ in the presence of graphite and magnetite, and at geochemical barriers with an acid reaction, and the activity of hydroxyl ions ensured the creation of a brannerite structure.

“Not Rural but Not Urban”: Community Governance in China's Urban Villages

2015 ◽  
Vol 223 ◽  
pp. 724-744 ◽  
Author(s):  
Beibei Tang
Keyword(s):  
Comparative Analysis ◽  
Social Welfare ◽  
Urban Governance ◽  
Urban Transformation ◽  
Community Governance ◽  
Governance Mode ◽  
Leading Role ◽  
The Village ◽  
Urban Administration ◽  
Urban Villages

AbstractChina's urbanization has created a large number of urban villages which, although they have been transferred to urban administration, have maintained their collective economies. Using a comparative perspective, this article investigates how villagers, the village collectives and the urban administration organize community governance in three urban villages on the fringes of the cities of Guangzhou, Wuhan and Shenyang. The findings suggest that successful village collective shareholding companies play a leading role in community governance by providing villagers with economic and social welfare, subsidizing community administration services, and mobilizing residents. The comparative analysis also shows that village shareholding companies employ different mechanisms based on the varied histories of their village collective economies, the ability of the village collectives to mobilize resources, and the degree to which the village collectives are engaged in the grassroots administrative structure. The article argues that the “not rural but not urban” governance mode of the urban villages illustrates China's fragmented urbanization planning. At the same time, it illuminates the dynamics of state–society relations during China's urbanization and how landless villagers and village collectives respond to urban transformation by adopting different strategies to preserve their individual and collective interests.

Early crust of the Podolia Domain of the Ukrainian Shield: Isotopic age of terrigenous zircons from quartzites of the Bug Group

2015 ◽  
Vol 23 (6) ◽  
pp. 555-567 ◽  
Author(s):  
E. V. Bibikova ◽  
A. A. Fedotova ◽  
S. Claesson ◽  
L. M. Stepanyuk
Keyword(s):  
Ukrainian Shield ◽  
Isotopic Age

A STATISTICAL ANALYSIS OF SOME AEROMAGNETIC MAPS FROM THE NORTHWESTERN CANADIAN SHIELD

Geophysics ◽  
1964 ◽  
Vol 29 (4) ◽  
pp. 582-601 ◽  
Author(s):  
C. W. Horton ◽  
W. B. Hempkins ◽  
A. A. J. Hoffman
Keyword(s):  
Statistical Analysis ◽  
Structural Information ◽  
Wave Length ◽  
Magnetic Anomalies ◽  
Geological Structure ◽  
Spectral Techniques ◽  
Structural Trend ◽  
Power Spectral ◽  
Good Agreement ◽  
Geologic Data

Autocovariance and power‐spectral techniques are applied to aeromagnetic maps from the District of MacKenzie, Northwest Territories, Canada, to obtain trend directions and other structural information. Such trends are representative of the geologic structures creating the magnetic anomalies, and they are subjected to structural analysis. Results of computations for four maps 17×17 miles in size and one profile 185 miles long show good agreement with the known geological structure of the region. These analyses predict a dominant structural trend from S 18° W to N 18° E and two associated conjugate shear directions. In addition, an unexplained basic periodicity with a wave length of 15 miles is shown. This type of statistical analysis is suggested as a new tool for the extension of geologic data into inaccessible or covered regions.

Research on the isotopic age of the Sinian–Cambrian boundary at the Meishucun section in Jinning County, Yunnan Province, China

1984 ◽  
Vol 121 (3) ◽  
pp. 171-173 ◽  
Author(s):  
Xue Xiaofeng
Keyword(s):  
Black Shale ◽  
Yunnan Province ◽  
Early Cambrian ◽  
Isotopic Age ◽  
Isotopic Dating

AbstractIn this paper the author describes the results of the Rb-Sr isotopic dating of black shale at the Sinian (Precambrian)–Cambrian boundary at the Meishucun section, Jinning County, Yunnan Province, China. The Sinian and Cambrian strata in eastern Yunnan are well developed, the Sinian–Cambrian boundary section in the vicinity of Meishucun Village in Jinning County being representative. These well developed strata provide excellent conditions for research on the radiometric age of the Precambrian–Cambrian boundary. An Rb-Sr isochron age of 579.7 ±8.2 Ma has been obtained on black shale from the Badaowan Member of the Early Cambrian Qiongzhusi Formation, which occurs at 20 m above the Sinian–Cambrian boundary. So an inferred age of 610±10 Ma is given for the Sinian (Precambrian)–Cambrian boundary.

scholarly journals Auto-Radiation Damages in Zircons of the Yastrubtsi Ore Occurrence of the Ukrainian Shield According to the Data of NMR and XRD

2021 ◽  
Vol 43 (1) ◽  
pp. 25-33
Author(s):  
A.E. GRECHANOVSKY ◽  
A.M. KALINICHENKO ◽  
E.E. GRECHANOVSKAYA ◽  
A.B. BRIK
Keyword(s):  
Mas Nmr ◽  
Ukrainian Shield ◽  
Degree Of Crystallinity ◽  
Initial Structure ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Radiation Damages ◽  
The Degree Of Crystallinity ◽  
Good Agreement ◽  
Xrd Method

By the method of XRD and high-resolution nuclear magnetic resonance (MAS NMR), the features of the structure of partially metamict zircons from Yastrubtsi ore occurrence of the Ukrainian Shield were studied. Samples 1 and 2 (depths 627 and 1069 m) belong to middle metamict zircons, and sample 3 (depth 1302.5 m) — to weak metamict zircons. The purpose of this work was to elucidate the features of the structure of partially metamictic zircons from Yastrubtsi ore occurrence of the Ukrainian Shield and the features of their recrystallization. The XRD method showed the presence of diffuse diffraction bands, which indicates the presence of an amorphous phase. For sample 3, these bands are less pronounced. After heating at T = 1100°C, these bands significantly decrease. Based on the XRD data, the degree of crystallinity and unit cell parameters of the samples were calculated. To obtain information on the local structure of the samples, spectra were obtained for the initial and annealed samples. It was shown by MAS NMR that there are regions in the initial structure in which [SiO4] tetrahedra are interconnected. These regions are designated Qn (n is the number of bridging oxygen atoms per Si atom). It has been established that the silica phase is practically absent in the zircon samples. In such samples, mainly Q1-2 and Q3 polymerization of silicon atoms occurs (for sample 3, only Q1-2 polymerization is characteristic). The MAS NMR results are in good agreement with the XRD data.

scholarly journals On the question of geological prerequisites of Dnieper-Donets depression hydrodynamic traps formation

2021 ◽  
Keyword(s):  
Water Exchange ◽  
Oil And Gas ◽  
Geological Structure ◽  
Hydrodynamic Type ◽  
Donets Basin ◽  
Main Task ◽  
Leading Role ◽  
Geophysical Study ◽  
Northern Side ◽  
Almost All

Formulation of the problem. Hydrocarbon pools in hydrodynamic traps are known within many oil and gas provinces. The Dnieper-Donets basin is one of the regions where non-vault traps of almost all types and associated with them hydrocarbon pools are widespread, while HT in DDD are not yet typical, although the geological structure of the region indicates the possibility of their formation. Thus, substantiation of the role of geological preconditions in the processes of hydrodynamic type traps formation is the main task of the work. Analysis of recent research and publications. In the monograph of O. Plotnikov (2001) among the promising regions for the search for HT defined DDD. The reason for this was the data on the presence in some productive horizons, in particular in the Sorochinsky and Rudenkivsky fields, of formation waters that lie above gas-bearing deposits. It is believed by some researchers, that the leading role in the formation of gas accumulations at these fields belongs to formation waters. According to the results of geological and geophysical study of the southern slope of the Kalmius-Torets depression and the Krasnoarmijska monocline in the south-eastern part of the DDD (A. Terdovidov (2000), S. Pavlov (2004), favorable geological prerequisites for the formation of HT in Paleozoic sediments established. Selection of previously unsolved parts of the overall problem. The general problem of searching for HT in the DDD as a whole task has not been solved so far. Formulation of the purpose of the article. Estimation of possibilities of a new direction of search and reconnaissance works in DDD, namely on non-traditional non-vault traps of hydrodynamic type substantiation. Results. The Visean dominant productive complex, regionally extended on the monocline slopes of the northern and southern sides of the depression and lithologically represented mainly by sandy horizons, was selected for priority research. The significant content of alluvial sandstones in Visean sediments section allowed the authors to consider them as special reservoirs of fluids, and paleoalluvial systems to study in the rank of independent search objects. Their territorial location is logically related to the existing deflections of the surface of the crystalline basement, most of which are associated with modern river systems, which indicates the current functioning of their relationship. The authors made an attempt to substantiate within the northern side of the DDD the following forecast water exchange systems: 1) expultional overflowing; 2) docking regime (both in the terminology of O. Plotnikov) in Paleozoic sediments; 3) infiltration water exchange in Mesozoic sediments, as necessary conditions for catching migrating upward hydrocarbons. The decrease in the infiltration waters velocity to insignificant values is interpreted by the authors as a typical phenomenon for "closed" monoclines, within which there was an equilibrium between the pressure of infiltrative waters and the resistance of expultional fluids. This equilibrium is seen as a term of creating conditions for hydrodynamic trapping. The conclusions emphasize the need for comprehensive research to confirm the predictive models of water exchange and obtain data for mapping piezometric minimums, where there is an presumable accumulation of hydrocarbons.

Sign in / Sign up

Export Citation Format

Share Document