The Zirconometry and Thermochronology of Migmatized Gneisses of the Gondaray Metamorphic Complex (Greater Caucasus)

2020 ◽  
Vol 75 (5) ◽  
pp. 481-495
Author(s):  
V. Yu. Gerasimov ◽  
V. A. Snezhko ◽  
J. Mosar ◽  
A. N. Pismennyi ◽  
N. L. Enna ◽  
...  
Keyword(s):  
Metamorphic Complex ◽  
Greater Caucasus

Zircons isotope dating and thermochronology of the migmatites from the Gondaray metamorphic complex of the Greater Caucasus

2020 ◽  
pp. 30-44
Author(s):  
V. Yu. Gerasimov ◽  
V. A. Snezhko ◽  
J. Mosar ◽  
A. N. Pis’mennyii ◽  
N. L. Enna ◽  
...  
Keyword(s):  
Isotope Composition ◽  
Crystalline Basement ◽  
Detrital Zircons ◽  
Time Range ◽  
Metamorphic Complex ◽  
Chemical Zoning ◽  
Greater Caucasus ◽  
Isotope System ◽  
Isotope Dating ◽  
Age Range

Results from isotope dating of the Greater Caucasus crystalline basement in the Elbrus subzone of the Main Caucasus Range inside of the HT gneiss-migmatite area of the Gondaray Metamorphic Complex is discussed herein. The measurements of the zircons isotope composition were performed on the ion microprobe SHRIMP-II at the CIR VSEGEI (St. Petersburg). All zircon crystals from the gneiss sample N 526 show chemical zoning and an old clastogenic core. Almost all U-Pb isotope dating points toile on the concordant line of the concordia diagram and show a wide age range from 320–1000 Ма, partially obtained from clastogenic grains of the zircon from the initial pelitic sediments. The youngest ages (320 Ма) belong to regenerating zones of the zircon grains recrystallized during stage of the anatexis and migmatization. The other part of the age range 540–1000 Ма belongs to detrital zircons from different magmatic sources that existed during accumulation of the proto-metamorphic sediments. Several clastogenic zircon grains show a Cambrian age, which is an evidence for the Early Paleozoic age of the metamorphic protolith. Traditionally the age of the Caucasus crystalline basement was suggested to be Precambrian. The ages of rim zones of the recrystallized zircons (320 Ма) have a direct correlation with postmetamorphic granite ages of the Greater Caucasus. It is shown by termochronological modeling that cooling of the Gondaray Metamorphic Complex during a retrogressive stage, from the temperature of migmatite crystallization (650 оС) to the moment of biotite K-Ar isotope system closure temperature (350 оС), was relatively fast (rate of cooling 8–10 оС/Ma) at subisobaric conditions and during a time range about 30–40 Ма.

scholarly journals About the discovery of the late vendian basement within the Blyb metamorphic complex of the Greater Caucasus Fore Range Zone

2019 ◽  
Vol 487 (4) ◽  
pp. 409-413
Author(s):  
V. A. Kamzolkin ◽  
M. L. Somin ◽  
A. V. Latyshev ◽  
Y. P. Vid’japin ◽  
S. D. Ivanov
Keyword(s):  
Lower Boundary ◽  
Sharp Change ◽  
Metamorphic Complex ◽  
Greater Caucasus ◽  
Planar Structures ◽  
Geological Features ◽  
Middle Paleozoic ◽  
Tectonic Window ◽  
New Interpretation ◽  
Blyb Metamorphic Complex

New data are presented concerning the age and relationships with the overlapping rocks of the Balkan massif of quartz diorites located in the central part of the Blyb metamorphic complex of the Fore Range of the Greater Caucasus in the Malaya Laba river basin. For the first time, using modern geochronological methods, it is shown that the Balkan massif has Precambrian age. An estimate of the age of the rocks of the Balkan massif using the SHRIMP II method for three U-Pb datings gives an interval of 549 ± 7,4-574,1 ± 6,7 Ma. A new interpretation of the structure of the basement of the Fore Range is suggested, according to which the rocks of the Late Vendian basement are exposed in a tectonic window and overlapped by the Middle Paleozoic metamorphic rocks of the Armovka nappe, first identified by the combination of geological features. The lower boundary of the nappe is characterized by a sharp change in composition and a change in the orientation of planar structures. On the border with the Armovka nappe there is a thick blastomilonite pack.

The Late Vendian Basement within the Limits of the Blyb Metamorphic Complex, Peredovoi Range of the Greater Caucasus

2019 ◽  
Vol 487 (2) ◽  
pp. 877-880 ◽  
Author(s):  
V. A. Kamzolkin ◽  
M. L. Somin ◽  
A. V. Latyshev ◽  
Yu. P. Vidyapin ◽  
S. D. Ivanov
Keyword(s):  
Metamorphic Complex ◽  
Greater Caucasus ◽  
Blyb Metamorphic Complex

INVESTIGATION OF EROSION RESISTANCE OF GRAY-BROWN SOILS IN THE SOUTHEASTERN SLOPES OF THE GREATER CAUCASUS

2020 ◽  
pp. 47-49
Author(s):  
Aliyev Z.H.
Keyword(s):  
Erosion Resistance ◽  
Preventive Measures ◽  
Chemical Properties ◽  
Anthropogenic Factors ◽  
Erosion Process ◽  
Greater Caucasus ◽  
Sloping Lands ◽  
Set Up ◽  
Physical And Chemical ◽  
And Chemical Properties

In recent years, sharp changes have occurred in the state of sloping lands of Azerbaijan. There was tension from the influence of the anthropogenic factors on the mountain slopes. The fact that the erosion process is rein-forced in the research site. Due to lack of agrotechnical measures on the slopes erosion process has been strength-ened, soil flooded with soil, physical and chemical properties of the soil have deteriorated, nutritional elements are reduced, vegetation is reduced and destruction limit. For some reason, the purpose of the research was Aqsu, two land cuts were set up to determine the degree of actual erosion in the Qizmeydan village. prevent erosion intensity, take preventive measures to take and implement appropriate measures.

Sphagnum mosses (Sphagnaceae, Bryophyta) of mires Chefandzar and Masota in North Ossetia (Caucasus)

2018 ◽  
Vol 52 (2) ◽  
pp. 455-462 ◽  
Author(s):  
G. Ya. Doroshina ◽  
I. A. Nikolajev
Keyword(s):  
Plant Communities ◽  
The Other ◽  
North Caucasus ◽  
Sphagnum Mosses ◽  
Greater Caucasus ◽  
The North ◽  
First Time ◽  
North Ossetia

Sphagnum mires on the Greater Caucasus are rare, characterized by the presence of relict plant communities of glacial age and are in a stage of degradation. The study of Sphagnum of Chefandzar and Masota mires is carried out for the first time. Seven species of Sphagnum are recorded. Their distribution and frequency within the North Caucasus are analyzed. Sphagnum contortum, S. platyphyllum, S. russowii, S. squarrosum are recorded for the first time for the study area and for the flora of North Ossetia. The other mosses found in the study area are listed.

Materials to the lichen flora of Samurskiy Ridge (high mountainous Dagestan)

2018 ◽  
Vol 52 (2) ◽  
pp. 397-406
Author(s):  
A. B. Ismailov ◽  
G. P. Urbanavichus
Keyword(s):  
North Caucasus ◽  
Lichenicolous Fungi ◽  
Greater Caucasus ◽  
Altitudinal Range ◽  
The North ◽  
New Findings ◽  
Mountainous Landscapes ◽  
First Time ◽  
Lichen Flora

The lichens and lichenicolous fungi of high mountainous landscapes of Samurskiy Ridge were studied in altitudinal range 2400–3770 m a. s. l. for the first time and 112 species are recorded. Among them 33 species, 10 genera (Arthrorhaphis, Baeomyces, Calvitimela, Epilichen, Lambiella, Psorinia, Rufoplaca, Sagedia, Sporastatia, Tremolecia) and 4 families (Anamylopsoraceae, Arthrorhaphidaceae, Baeomycetaceae, Hymeneliaceae) are new for Dagestan, six species (Buellia uberior, Carbonea atronivea, Lecanora atrosulphurea, Lecidea fuliginosa, L. swartzioidea, Rhizoplaca subdiscrepans) are reported for the first time for the Greater Caucasus and two species (Acarospora subpruinata and Rhizocarpon postumum) — for the North Caucasus. Most of the new findings were collected from 3500–3770 m a. s. l.

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