scholarly journals Polychronous zircons of volcanics of the Navysh complex of the Lower Riphean Ai Formation (Southern Urals)

Georesursy ◽  
2020 ◽  
Vol 22 (4) ◽  
pp. 101-112
Author(s):  
Artur A. Krasnobaev ◽  
Victor N. Puchkov ◽  
Nina D. Sergeeva ◽  
Sofia V. Busharina
Keyword(s):  
Age Groups ◽  
Lower Boundary ◽  
Complex Form ◽  
Southern Urals ◽  
Primary Sources ◽  
The Southern Urals ◽  
Geochemical Properties ◽  
Previous Cycle ◽  
Lower Riphean ◽  
Frequent Presence

The volcanics of the Navysh complex of the Lower Riphean Ai Formation in the Southern Urals are well studied petrochemically and dated by several methods. In 2013 zircons from a trachybasalt porphyrite (sample 2152) gave a concordant SHRIMP date 1752±11 Ma, which was used as a fundamental for the lower boundary of the Riphean with no special arguments against it. The later attempts to repeat this date for the Navysh volcanics were not successful: the collected zircons were either more ancient (> 2500 Ma), or more young (< 500 Ma). From the beginning, the zircons with such ages were regarded as xenogenic or secondary metasomatic, or belonging to paleozoic dykes intruding the Riphean volcanics. However, the clearly expressed mineralogical properties of the Paleozoic zircons and their frequent presence in volcanics, not dykes, led to a conclusion that the zircons and Navysh volcanics, containing them, and exposed within the area of development of the Ai Formation, are polychronous. To support this conclusion, the authors studied in more detail the zircons of the Navysh trachybasalts, developed in the Ai Formation. The main conclusion, obtained from this new data, was that the volcanics attributed to the Navysh complex, form a polychronous system, including both the Lower Riphean (1750 Ma) and Paleozoic (450 Ma) rocks. The zircons of these age groups differ in their mineralogical and geochemical properties supporting the idea that they belong to different primary sources which may be due to repeating plume processes, which partly reanimated – heated and melted-rocks of the previous cycle and/or created new sources of melts.

The Sr isotopic characterization and Pb-Pb age of carbonate rocks from the Satka formation, the Lower Riphean Burzyan Group of the southern Urals

2008 ◽  
Vol 16 (2) ◽  
pp. 120-137 ◽  
Author(s):  
A. B. Kuznetsov ◽  
G. V. Ovchinnikova ◽  
M. A. Semikhatov ◽  
I. M. Gorokhov ◽  
O. K. Kaurova ◽  
...  
Keyword(s):  
Carbonate Rocks ◽  
Southern Urals ◽  
The Southern Urals ◽  
Lower Riphean ◽  
Isotopic Characterization ◽  
Burzyan Group

scholarly journals The sources of zircons in clastic rocks of the Riphean deposits of the Urals

2019 ◽  
Vol 488 (4) ◽  
pp. 413-419
Author(s):  
A. A. Krasnobaev ◽  
V. N. Puchkov ◽  
N. D. Sergeeva ◽  
S. V. Busharina
Keyword(s):  
Southern Urals ◽  
Detrital Zircons ◽  
The Other ◽  
The Urals ◽  
The Southern Urals ◽  
Clastic Rocks ◽  
Lower Riphean ◽  
Age Variations ◽  
Age Determinations

New age determinations of detrital zircons of sandstones augmented the possibilities of interpretation of their provenance. This interpretation is often restricted by a formal comparison of age-and-composition characteristics of detrital crystals with any very distant model objects. A different situation arises when the role of a source of a detritus is claimed by local objects. The analysis of SHRIMP and TIMS - datеs of zircons and U and Th concentrations in them, and also a comparison of histograms of primary zircons from Riphean volcanics and rocks of the Taratash complex on one hand and the detrital zircons from the sandstones of Vendian (Asha series) and Lower Riphean (Ai Formation) on the other, have shown that the age variations of sources and clastics are comparable in many aspects. It means that the age characteristics of primary zircons from the Riphean volcanics and rocks of the Taratash complex as sources of zircon clastics for the Riphean and Vendian sandstones in the Southern Urals are regulated by processes of resedimentation, though the influence of distant sources is not excluded.

The Lower Boundary of the Vendian in the Southern Urals as Evidenced by the Rb–Sr Age of Glauconites of the Bakeevo Formation

2019 ◽  
Vol 27 (5) ◽  
pp. 573-587 ◽  
Author(s):  
T. S. Zaitseva ◽  
A. B. Kuznetsov ◽  
V. M. Gorozhanin ◽  
I. M. Gorokhov ◽  
T. A. Ivanovskaya ◽  
...  
Keyword(s):  
Lower Boundary ◽  
Southern Urals ◽  
The Southern Urals

scholarly journals U-Pb (SHRIMP) age of zircons from granitoid pebbles of Kukkarauk conglomerates of Vendian asha series in the Alatau anticlinorium (Southern Urals)

2019 ◽  
Vol 486 (5) ◽  
pp. 598-602
Author(s):  
A. A. Krasnobaev ◽  
V. N. Puchkov ◽  
N. D. Sergeeva ◽  
S. V. Busharina
Keyword(s):  
Lower Boundary ◽  
Southern Urals ◽  
The Southern Urals ◽  
Radiometric Data

The absence of reliable radiometric data in Vendian deposits of the Uralian and other regions resulted in uncertainty of the ideas of the age of the lower boundary of Vendian. According to the decision of the Interdepartment Stratigraphic Committee, it is located at 600 ±10 Ma. Analysing zircons of granitoid pebbles from Kukkarauk Formation of the standard sections of Vendian in the Alatau anticlinorium, the authors obtained a concordant SHRIMP date - 713.6 ± 6.1 Ma; practically, it is up to now the only reliable date that can be used as a reference for the rocks in the provenance area of the Vendian basin in the Southern Urals which witness for a Vendian erosion of granites which are alike the granites of the Mazara and Barangulovo massifs, situated in the northern part of the Uraltau zone of the Southern Urals, to the east of the area of Vendian sedimentation.

Formation Conditions of Ferromagnesian Metasomatic Carbonates in the Lower Riphean Terrigenous–Carbonate Rocks of the Southern Urals

2019 ◽  
Vol 54 (3) ◽  
pp. 248-261
Author(s):  
M. T. Krupenin ◽  
S. V. Michurin ◽  
A. A. Sharipova ◽  
A. A. Garaeva ◽  
D. A. Zamyatina ◽  
...  
Keyword(s):  
Carbonate Rocks ◽  
Southern Urals ◽  
The Southern Urals ◽  
Lower Riphean ◽  
Formation Conditions

scholarly journals Zircons of the Permian age (280–290 Ma) from intrusive magmatic rocks in Riphean structure of the Southern Urals

LITOSFERA ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 601-608
Author(s):  
A. A. Krasnobaev ◽  
V. N. Puchkov ◽  
N. D. Sergeeva ◽  
S. V. Busharina
Keyword(s):  
Southern Urals ◽  
Lower Permian ◽  
The Urals ◽  
Shrimp Dating ◽  
The Southern Urals ◽  
Lower Paleozoic ◽  
Magmatic Rocks ◽  
Lower Riphean ◽  
Granite Complex ◽  
A Chain

Research subject. Magmatic complexes that are developed in the lower (volcanogenic-sedimentary) part of the Ai Formation of the Lower Riphean of the Taratash anticline in the Southern Urals. Results. For the frst time, the Lower Permian SHRIMP dating (288.6 ± 3.1 Ma by U-Pb method on zircon from monzogabbro) was obtained for a dike cutting the basalts of the Lower Paleozoic (420–450 Ma) age. Conclusions. On the eastern slope of the Urals there is a chain of massifs which are close in the age. The chain belongs to the Lower Permian Stepninsky monzogabbro-granosyenite-granite complex, represented by the Uiski, Vandyshevski, Biryukovski and Stepninski intrusions with the age of 281 ± 2, 280 ± 2 and 286 ± 2 Ma, correspondingly (U-Pb method after zircons, SHRIMP-II, VSEGEI) and earlier obtained dates 281 ± 4 Ma (Rb-Sr isochrone) and 283 ± 2 Ma (isotope Pb-Pb method after zircons). The Stepninsky complex was described earlier as plume-dependent. The monzogabbro dike, described in this paper, although being at a considerable distance from the Sepninsky complex, is situated at a strike of the chain of the stepninsky intrusions, is close to them by the composition and age and can be ascribed to the same plume episode. The idea of the plume character of the complex was ехрressed by us relatively long ago based on a superimposed character of the chain of the intrusions over the earlier, collisional Uralian structures. As for the geochemical character (monzogabbro) the dike conforms with one of two standard trends of the Stepninsky complex – monzonite (monzogabbro, monzodiorites, syenites).

scholarly journals The Lower Precambrian in the structure of paleozoic in the Subpolar Urals

2019 ◽  
Vol 486 (5) ◽  
pp. 572-576
Author(s):  
Yu. I. Pystina ◽  
A. M. Pystin ◽  
V. B. Hubanov
Keyword(s):  
Southern Urals ◽  
Western Slope ◽  
Geochronological Data ◽  
The Urals ◽  
The Southern Urals ◽  
Early Precambrian ◽  
Subpolar Urals ◽  
Late Precambrian ◽  
Lower Riphean ◽  
First Time

In many polymetamorphic complexes of the Urals, rocks with Early Precambrian age marks have been established. But only with respect to the two polymetamorphic complexes located on the western slope of the Southern Urals: the Taratash and Aleksandrov, their indisputable belonging to the Archean-Paleoproterozoic section is recognized. They are framed by weakly metamorphosed Lower Riphean sediments and reliable geochronological data are obtained from them, which unambiguously indicate the Early Precambrian age of rock metamorphism. The available Early Precambrian age datings for other Ural polymetamorphic complexes (with the prevailing number of Late Precambrian and Paleozoic age values) are interpreted differently. Therefore, their attitude to the Lower Precambrian section has been disputed by many researchers. In the article, for the first time, based on the results of mass U-Pb dating of metamorphic zircons from the gneiss of the Nyrtin polymetamorphic complex of the Subpolar Urals, taking into account the available data, the Paleoproterozoic age of the earliest stage of rocks metamorphism (2127 ± 31 Ma) is substantiated. This gives grounds to assert that the complex under consideration, as well as the Taratash and Alexandrov complexes of the Southern Urals, belongs to the Lower Precambrian formations involved in the structure of Uralides.

Diagenesis of Carbonate and Siderite Deposits of the Lower Riphean Bakal Formation, the Southern Urals: Sr Isotopic Characteristics and Pb-Pb Age

2005 ◽  
Vol 40 (3) ◽  
pp. 195-215 ◽  
Author(s):  
A. B. Kuznetsov ◽  
M. T. Krupenin ◽  
G. V. Ovchinnikova ◽  
I. M. Gorokhov ◽  
A. V. Maslov ◽  
...  
Keyword(s):  
Southern Urals ◽  
The Southern Urals ◽  
Lower Riphean

Evaluation of Effects of Diagnostic Exposure Using Data from Epidemiological Registry of Ozyorsk Population Exposed to Computed Tomography

2020 ◽  
Vol 65 (4) ◽  
pp. 65-79
Author(s):  
M. Osipov ◽  
E. Fomin ◽  
M. Sokolnikov
Keyword(s):  
Computed Tomography ◽  
Effective Dose ◽  
Age Groups ◽  
Malignant Neoplasm ◽  
Southern Urals ◽  
Malignant Neoplasms ◽  
Study Cohort ◽  
Low Doses ◽  
The Southern Urals ◽  
Diagnostic Radiation

Purpose: To assess the contribution of low doses of diagnostic radiation due to computed tomography to carcinogenic risk among population of Ozersk. Material and methods: The study describes the results of the analysis of data from the radiation-epidemiological register created in the laboratory of radiation epidemiology of the Southern Urals Biophysics Institute of Ozersk. The register contains information on 26,626 CT examinations of Ozersk residents of all age groups, including children under 1 year old, carried out in medical departments of the Chelyabinsk region during the period from 1993 to 2018. Results: Based on the analyzed medical and dosimetric information from the CT Register database, the chances of malignant neoplasms among patients exposed to diagnostic irradiation during computed tomography were assessed taking into account the presence of the main radiation and non-radiation factors (age, sex, occupational exposure, number of CT examinations, effective dose and DLP). Conclusion: In a cohort of Ozersk residents who were exposed to low doses of diagnostic radiation during computed tomography, a statistically significant effect of sex and age attained to malignant neoplasm was obtained. Also, a significant relationship was found between the effective dose from diagnostic CT and the likelihood of subsequent cancer development diagnosed no earlier than 2 years after the first CT examination. At the same time, the DLP did not statistically significantly increase the chances of developing a malignant neoplasm in the study cohort for both the population and the personnel of the Mayak PA.

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