scholarly journals Distribution of Trace Elements Controlled by Sector and Growth Zonings in Zircon from Feldspathic Pegmatites (Ilmen Mountains, the Southern Urals)

Geosciences ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 7
Author(s):  
Ekaterina V. Levashova ◽  
Sergey G. Skublov ◽  
Vladimir A. Popov
Keyword(s):  
Trace Elements ◽  
Distribution Pattern ◽  
Southern Urals ◽  
Zircon Crystal ◽  
Ion Microprobe ◽  
Growth Sector ◽  
Scattered Electron ◽  
The Southern Urals ◽  
Sector Zoning ◽  
Growth Zoning

The present study contains the detailed ion microprobe data on trace and rare earth elements distribution in the large zircon crystal about 10 × 6 mm in size with distinct growth and sector zonings from Ilmen Mountains feldspathic pegmatite. The zircon crystal morphology is a combination of a prism {110} and a dipyramid {111}. It is found out that the growth sector of the prism {110} generally contains higher concentrations of Th, U, REE, Y, and Nb and exhibits a more gently sloping HREE distribution pattern and a steeper LREE distribution pattern, in contrast to zircon from the growth sector of the dipyramid {111} development. Such a sector zoning pattern was formed at a late stage in crystal growth, when the prism {110} began to prevail over the dipyramid {111}. The zircon studied displays the growth zoning formed of alternating bands in back-scattered electron (BSE) image: wide dark and thin light bands. The last ones contain elevated Th, U, REE, Y, Nb, and Ti concentrations, Th/U ratio and Ce/Ce*. This growth zoning is most probably due to simultaneous crystallization of other minerals that concentrate trace elements, e.g., apatite and monazite, and the lack of equilibrium between zircon and fluid (melt).

U-Pb age and metamorphism of rocks of Voshnevogorsky sequence (South Ural)

2020 ◽  
pp. 51-62
Author(s):  
A. A. Krasnobaev ◽  
P. M. Valizer ◽  
E. V. Medvedeva ◽  
A. B. Nemov ◽  
A. L. Perchuk
Keyword(s):  
Southern Urals ◽  
Ion Microprobe ◽  
The Urals ◽  
The Southern Urals ◽  
Geochemical Study ◽  
Age Range ◽  
Host Rocks ◽  
Eastern Domain ◽  
Proterozoic Age

In the article present results of U-Pb — dating of zircons and petrologic-geochemical study of garnet-biotite plagiogneises and quartz-plagioclase-amphibole granofels host rocks samples from Vishnevogorsky sequence of the oldest rocks of the southern Urals Eastern domain are presented. U-Pb-dating of zircons were obtained by ion microprobe (SHRIMP II). The maximum age of the substrate plagiogneises Vishnevogorsky sequence not younger than 2700 Ma, and granulitic metamorphism plagiogneises falls on the Proterozoic age range 1740–2220 Ma. The dates obtained for plagiogneises and granofels Vishnevogorsky sequence reflect all major (PR1–P1) age stages of the Urals development. Many of the dated events are manifested only in the zircons generation and are not reflected in the mineral paragenesises of the studied rocks.

scholarly journals Limestones of the Uk Formation (Upper Riphean, the Southern Urals): Effect of contamination and diagenetic fluids on the distribution of rare-earth elements and yttrium

LITOSFERA ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 23-31
Author(s):  
A. V. Maslov
Keyword(s):  
Trace Elements ◽  
Carbonate Rocks ◽  
Southern Urals ◽  
Strong Positive Correlation ◽  
The Southern Urals ◽  
Positive Correlation ◽  
Fine Grained ◽  
Upper Riphean ◽  
Diagenetic Fluids ◽  
The Uk

Research subject. A study was conducted into the geochemical features of various lithotypes of carbonate rocks (granular and clastic limestones, limestones with planar, planar-columnar and columnar stromatolites) from the upper subformation of the Uk Formation. This formation crowns the Upper Riphean Karatau Group on the Western slope of the Southern Urals (Bashkir meganticlinorium). Material and methods. The research material was two collections of carbonate rocks (11 and 32 samples), the general geochemical features of which were previously considered in publications in 2019. The main research method was the analysis of the correlation relationships of the main rock-forming components, trace elements and their indicator relationships. Research results. It was established that all lithotypes are characterized by a significant content of both the main rock-forming components and the trace elements that make up the insoluble residue/fine-grained terrigenous admixture. This suggests that the area of accumulation of carbonate sediments was located near the continent, which served as a source of a significant amount of fine-grained/clay suspension. Conclusions. A strong positive correlation was observed between K2O and REE in the carbonate rocks of the Upper Uk Subformation, and a strong negative correlation was observed between REE and CaO. This suggests that the REE content in carbonate rocks is controlled mainly by terrigenous/clay admixture. A positive correlation is also observed between REE and Th, Zr, and Al2O3. All this shows that REE in carbonate rocks are mainly present in clay admixtures. The correlation coefficient between Ce/Ce* and (Dy/Sm)N is 0.20, while this coefficient for Eu/Eu* and (Pr/Sm)N equals 0.12. Thus, a definite conclusion about the effect of diagenetic fluids on the distribution of REE cannot be made. The data obtained show that the distribution of REE and Y in our collection of carbonate rocks of the Upper subformation of the Uk Formation of the Southern Urals is controlled mainly by clay admixtures.

scholarly journals Trace-elements in minerals from unusual rocks of the Southern Urals

LITOSFERA ◽  
2019 ◽  
pp. 269-292
Author(s):  
V. G. Korinevsky ◽  
K. A. Filippova ◽  
V. A. Kotlyarov ◽  
E. V. Korinevsky ◽  
D. A. Artemyev
Keyword(s):  
Trace Elements ◽  
Southern Urals ◽  
Petrographic Analysis ◽  
The Southern Urals ◽  
Chemical Homogeneity ◽  
Icp Ms ◽  
Wide Range ◽  
Host Rocks ◽  
First Time

Research subject. This articles presents the data obtained in the course of 75 analytical studies on a wide range of minerals (amphiboles, pyroxenes, garnets, spinels, olivines, anorthites, corundums, epidotes, apatites, clinochlore, dolomite, calcite, zircon) contained in igneous and metamorphic Southern Urals rocks. In addition, information is provided about the content of trace elements, including rare earth (REE) ones, in these rocks. The data on the content of trace elements in some minerals are presented for the first time (höegbomite, sapphirine, zoisite, clinozoisite, gedrite, cummingtonite, anthophyllite, potassium-magnesiohastingsite). Materials and methods. A petrographic analysis of rocks containing the minerals under study was carried out. A particular attention was paid to petrographic analysis of rocks containing the minerals under study was carried out. A particular attention was paid to “fresh” rocks, containing the mineral under study which rarely occur in the Urals. These rocks feature inclusions of serpentinite melange in the form of plates and lenses among the metamorphic strata (schists, gneisses, and amphibolites) and are characterized by the preservation of primary structures, relative chemical homogeneity, as well as the presence of simultaneous growth surfaces between most minerals. Of particular research interest were minerals from rocks, the composition of which had been relatively poorly studied (pyroxene-amphibole anorthite gabbro and gabbro-amphibolites, scapolite rocks, hornblendite, gedrite-cummingtonite-anthophyllitic crystallo-schists and amphibolites, ore-less carbonatites). The composition of mineral samples was determined using a scanning microscope REMMA-202 M equipped with an energy dispersive console and a mass-spectrometer Agilent 7700x (ICP-MS and LA-ICP-MS methods). Results. Petrographic characteristics of the rocks containing the minerals under study are given. The geographical coordinates of locations, where mineral sampling was performed, are provided. The content of trace elements is shown to vary greatly within related species of minerals (amphiboles, garnets, pyroxenes, olivines, epidotes, spinels, mica, etc.), with the fluctuations being independent of the alkalinity of host rocks or their geological nature.Conclusions. For the first time, a significant role of zoisite and clinozoisite in the process of concentrating trace elements, including REE, has been revealed. The role of apatite as one of the main mineral concentrators of REE has not been confirmed either in the main and ultrabasic rocks, or in some calcite-dolomite carbonatites. 

The first data on possible Mezozoic magmatism within the Western slope of the Southern Urals

2018 ◽  
pp. 24-34
Author(s):  
A. O. Khotylev ◽  
N. B. Devisheva ◽  
Al. V. Tevelev ◽  
V. M. Moseichuk
Keyword(s):  
Southern Urals ◽  
Western Slope ◽  
Isotopic Age ◽  
The Southern Urals ◽  
Early Proterozoic ◽  
Carbonate Formations ◽  
Two Bodies

Within the Western slope of the Southern Urals, there are plenty of basite dyke complexes of Riphean to Vendian among Precambrian terrigenous-carbonate formations. In metamorphic formations of the Taratash complex (Archean to Early Proterozoic, the northern closure of the Bashkirian meganticlinorium) there was observed the andesitic dyke with isotopic age of 71±1 Ma (U-Pb SHRIMP II on zircons) and near Bakal two bodies of gabbroids with zircons of similar ages were found. These are the first evidence of possible Mezozoic magmatism in this region.

ABOUT THE PHYTOCENOTIC ROLE OF THE DARKNOUS SPECIES IN THE SOUTHERN URALS

2017 ◽  
Vol 212 (12) ◽  
pp. 48-50
Author(s):  
Ju.P. Gorichev ◽  
◽  
A.N. Davydychev ◽  
A.Yu. Kulagin ◽  
◽  
...  
Keyword(s):  
Southern Urals ◽  
The Southern Urals
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