scholarly journals On the age of pyrochlore carbonatites from the Ilmeno-Vishnevogorsky Alkaline Complex, the Southern Urals (insights from Rb-Sr and Sm-Nd isotopic data)

LITOSFERA ◽  
2020 ◽  
Vol 20 (4) ◽  
pp. 486-498
Author(s):  
I. L. Nedosekova ◽  
V. A. Koroteev ◽  
T. B. Bayanova ◽  
P. A. Serov ◽  
V. I. Popova ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Southern Urals ◽  
Tectonic Activity ◽  
Ionization Mass ◽  
Alkaline Complex ◽  
Carbonatite Complex ◽  
The Southern Urals ◽  
Scientific Center ◽  
Linear Type ◽  
Isotopic Compositions

Research subject. In this research, we carried out Sm-Nd- и Rb-Sr-dating of pyrochlore carbonatite from the Vishnevogorsky niobium deposit, Ilmeno-Vishnevogorsky Alkaline Complex, Southern Urals. IVC is located in the Ural fold region and is a carbonatite complex of the linear type. Rare metal (Nb-Zr-TR) deposits and occurrences are related to IVC. The age and the duration of IVC deposits formation remains a matter of debate. To determine the age of IVC carbonatites and related niobium ore, we measured Sm-Nd and Rb-Sr isotopic compositions and concentrations of the elements in the minerals (pyrochlore, calcite, apatite, biotite) and bulk sample of pyrochlore carbonatite. Materials and methods. The Sm and Nd isotopic compositions and concentrations were determined on a Finnigan MAT-262L (RPQ) seven-collector mass spectrometer in the static regime at the Geological Institute of the Kola Scientific Center, Apatity, Russia. The Sr and Rb isotopic compositions and concentrations were determined on thermos-ionization mass spectrometer Triton Plus (“Geoanalitik”, IGG UD RAN, Ekaterinburg, Russia). Results. Age of pyrochlore carbonatites from ore zone 140 (Vishnevogorsky deposit, IVC) defined by Sm-Nd and Rb-Sr isotopic methods. Mineral Sm-Nd-isochron (5 points) indicated age 229 ± 16 Ma, mineral Rb-Sr-isochron (5 points) showed similar age 250.5 ± 1.2 Ma. Conclusions. Results Sm-Nd и Rb-Sr dating indicate that the pyrochlore сarbonatites of ore zone 140 crystallized ≈ 250 Ma ago, at the stage of the postcollisional extension, possibly, in connection with exhumation complex, which was accompanied by decompression, partial melting of rocks, involving fluids, dissolution and precipitation of Ordovician-Silurian alkaline-carbonatitе complex. Thus, the formation of the IVC carbonatites and related Nb-ore, which began in Silurian (S), continued in Permian (P) and Triassic (T1-2) and was associated with the post-collision stage of tectonic activity in the Ural Fold Belt.

scholarly journals REE, Y, Th, U and Mn systematics of Upper Devonian conodonts in the West Uralian Folded Zone (Southern Urals)

LITOSFERA ◽  
2019 ◽  
pp. 250-268
Author(s):  
A. V. Maslov ◽  
O. V. Artyushkova ◽  
R. Ch. Tagarieva ◽  
D. V. Kiseleva ◽  
M. V. Streletskaya ◽  
...  
Keyword(s):  
Mass Spectrometer ◽  
Inductively Coupled Plasma ◽  
Southern Urals ◽  
Measurement Procedure ◽  
Upper Devonian ◽  
Shelf Zone ◽  
Spectrometric Analysis ◽  
The Southern Urals ◽  
Inductively Coupled ◽  
Leading Role

Research subject. This article presents the results of a study undertaken to investigate the systematics of rare-earth elements (REE), Y, Th, U and Mn in the Upper Devonian conodonts of the Western Ural region of the foreland fold of the Southern Urals (Askyn and Makarovo horizons, Kukkarauk, Ryauzyak and Lemezinsky sections).Methods. The conodonts were isolated from carbonate rocks using the conventional method of their dissolution in organic acids, mainly formic acid. Sample preparation and mass spectrometric analysis were carried out in the class 1000 and 10 000 cleanroom facilities of the Zavaritsky Institute of Geology and Geochemistry. A PerkinElmer ELAN 9000 quadrupole ICP mass-spectrometer was used to determine the concentration of the trace elements under study. Sm and Nd isotope ratios were measured from a 3% nitric acid solution by a Thermo Fischer Neptune Plus multicollector inductively coupled plasma mass-spectrometer. The long-term reproducibility and accuracy of the measurement procedure were evaluated using a standard Merck Nd solution based on the NIST Nd2O3 and yielded 143Nd/144Nd = 0.511720 ± 15 (1 SD, n = 40).Results. The established features of PAAS-normalised lanthanide distributions in the conodont bulk samples (10.4–21.8 mg), Ce-anomalies, high REE values (173–1211 ppm) and a number of other parameters indicate the leading role of late diagenetic processes in the formation of conodont REE systematics. This is also evidenced by the Y/Ho values (≈26–32) specific for the studied conodont samples.Conclusions. In general, the distribution of lanthanides in the conodonts suggests that this process was mainly controlled by a lithogenic (from 90 to more than 99%) REE source. The εNd (t) (–4.0…–2.8) values characteristic of the cono donts of the Askyn and Makarovo horizons suggest that their Nd isotopic composition was either formed under the influence of the open ocean (island arc basin), characterised by a significant share of radiogenic Nd, or due to the entry of radiogenic waters of the ocean into the shelf zone at the peak of the marine transgression that took place in the region under consideration in the Famennian. 

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

Syntaxonomy of mid-successional stages of secondary forests of the central elevated part of the Southern Urals

2012 ◽  
pp. 109-134
Author(s):  
P. S. Shirokikh ◽  
A. M. Kunafin ◽  
V. B. Martynenko
Keyword(s):  
Boreal Forests ◽  
Floristic Composition ◽  
Southern Urals ◽  
Secondary Forests ◽  
Natural Forests ◽  
The Southern Urals ◽  
Active Growth ◽  
Tree Layer ◽  
Shade Tolerant Species ◽  
Successional Stages

The secondary birch and aspen forests of middle stages of succession of the central elevated part of the Southern Urals are studied. 4 subassociations, 1 community, and 7 variants in the alliances of Aconito-Piceion and Piceion excelsae are allocated. It is shown that the floristic composition of aspen and birch secondary forests in the age of 60—80 years is almost identical to the natural forests. However, a slight increase the coenotical role of light-requiring species of grasslands and hemiboreal forests in the secondary communities of the class Brachypodio-Betuletea was noticed as well as some reduction of role the shade-tolerant species of nemoral complex and species of boreal forests of the class Vaccinio-Piceetea. Dominant tree layer under the canopy of secondary series is marked by an active growth of natural tree species.

Caragano fruticis—Pinion sylvestris, the new alliance of xerophillous pine-larch forests of the Southern Urals

2002 ◽  
pp. 42-62 ◽  
Author(s):  
A. I. Solomeshch ◽  
V. B. Martynenko ◽  
O. Yu. Zhigunov
Keyword(s):  
Southern Urals ◽  
The Southern Urals ◽  
Larch Forests ◽  
Steep Slopes

Xerophillous pine-larch forests of the Southern Ural have been described as a new alliance Caragano fruti­cis—Pinion sylvestris. They occur on steep slopes of upper parts of mountain ridges with poorely developed stony soils. Alliance asigned to the class Brachypodio pinnati—Betuletea pendulae, order Chamaecytiso ruthe­nici—Pinetalia sylvestris. Associations Carici caryophyl­leae—Pinetum sylvestris and Ceraso fruticis—Pinetum sylvestris with four subassociations are described. Eco­logical and floristical peculiarities of new alliance in comparison with another alliances of the order Cha­maecytiso-Pinetalia and with siberian class Rhytidio rugosi—Laricetea sibiricae have been discussed.

Sign in / Sign up

Export Citation Format

Share Document