scholarly journals CARBONIFEROUS 40Ar/39Ar AGE OF THE RARE METAL-ENRICHED RHYOLITES AND IGNIMBRITES IN THE SAKMARA ALLOCHTHON OF THE SOUTHERN URALS, THEIR GEOCHEMICAL FEATURES AND GEODYNAMIC SETTING

2018 ◽  
pp. 23-32
Author(s):  
A. V. Ryazantsev ◽  
A. V. Pilitsina ◽  
I. A. Novikov ◽  
K. E. Degtyarev
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Southern Urals ◽  
Rare Metal ◽  
Geodynamic Setting ◽  
Volcanic Complex ◽  
The Southern Urals ◽  
The Matrix ◽  
Type Granite ◽  
Back Arc

In the structure of the Sakmara allochthon of the Southern Uralssequence with rhyolites and ignimbrites locally occures. They have Nb-Zr-REE geochemical specialization. This sequence unconformably overlays folded Paleozoic complexes, including the Devonian ones. Rhyolite contains K-feldspar and quartz phenocrysts, K-feldspar glomeroporphyrites and granite xenolith. Geochemical features of the rhyolites show intraplate-originated affinities and A-type granite composition.40Ar/39Ar age of the felsitic matrix of the rhyolites of 303±2 Ma defines the age of the volcanic complex origin. For feldspar phenocrysts the age of 306±3 Ma and 337±3 Ma is obtained. The first value coincides to the matrix age and connected with formation of the volcanic complex. The second value belongs, apparently, to xenogenic material. Obtained age values reflect the evolution of Carboniferous active continental margin magmatism, widespread in different structural zones of the Urals. Rare-metal rhyolites characterize the final late Carboniferous intraplate (rift-related) back-arc magmatism at the active continental margin. Volcanism preceded to a collision-related ophiolitic thrust nappes emplacement.

A Reconstruction of a Vendian–Cambrian Active Continental Margin within the Southern Urals: Results of Detrital Zircons Studying from Ordovician Terrigenous Rocks

Geotectonics ◽  
2019 ◽  
Vol 53 (4) ◽  
pp. 485-499 ◽  
Author(s):  
A. V. Ryazantsev ◽  
N. B. Kuznetsov ◽  
K. E. Degtyarev ◽  
T. V. Romanyuk ◽  
T. Yu. Tolmacheva ◽  
...  
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Southern Urals ◽  
Detrital Zircons ◽  
The Southern Urals ◽  
Terrigenous Rocks

Carboniferous 40Ar/39Ar Age of the Rare-Metal Enriched Rhyolites and Ignimbrites in the Sakmara Allochthon of the Southern Urals

2018 ◽  
Vol 483 (5) ◽  
pp. 529-534
Author(s):  
A. Ryazantsev ◽  
◽  
K. Degtyarev ◽  
A. Pilitsina ◽  
I. Novikov ◽  
...  
Keyword(s):  
Southern Urals ◽  
Rare Metal ◽  
The Southern Urals

scholarly journals Early Permian granitoids of the East Magnitogorsk zone (South- ern Urals): petrology, geochemistry, and geodynamic formation environment

2020 ◽  
Vol 1 (1) ◽  
pp. 47-62
Author(s):  
Timofey Nikolaevich SURIN ◽  
Keyword(s):  
Water Pressure ◽  
Southern Urals ◽  
Geodynamic Setting ◽  
Type I ◽  
Early Permian ◽  
The Southern Urals ◽  
Quartz Syenite ◽  
Crystallization Differentiation ◽  
Geochemical Study

The relevance of the problem. The Early Permian magmatism of the Southern Urals is poorly studied with the help of modern methods. The granitoid massifs of this age locally developed in the East Magnitogorsk zone contain important information about the geodynamic conditions of their formation. Clarification of this issue makes an important contribution to the understanding of the geodynamic development of the Urals. The nature of granitoids is still debatable. The connection with the massifs combined in the Balkan complex of gold-tungsten mineralization indicates the need for a comprehensive study. The purpose of the study is to determine the petrological and geochemical features of the rocks of the Balkan complex, to identify the mechanism of their petrogenesis and to establish the geodynamic conditions of their formation. Results. The petrological and geochemical study of the formations of the Balkan complex was carried out and their place in the typical taxonomy of granitoids was determined. Their belonging to the I-type is shown. Mineralogical and petrogeochemical methods were first studied for shonkinite xenoliths in granitoids. The mechanism of petrogenesis of rocks is proposed and the geodynamic setting of their formation is determined. It is shown that the monzonitemonzodiorite-quartz syenite-granosyenite-leucogranite series of rocks was formed as a result of crystallization differentiation of a single parental melting, and it was also concluded that the massifs of the complex are formed under conditions of early collision conditions with the important role of the subduction process. The mechanism of formation of the massifs of the complex is largely similar to mechanism for granitoids in other conflict areas, although it has its own specifics. Conclusions. 1). The Early Permian granitoids of the Balkan complex relates to type I. 2). All rocks of the complex, from monzonites to quartz syenites and leucogranites, including xenolith shonkinites, form a petrogenetic series formed as a result of crystallization differentiation of a single parent alkaline-gabbroic melting with increased water pressure. 3). The Balkan complex was formed in an early collisional setting under the action of deep subduction. 4). Transpression in the upper part of the crust induced formation of the massifs of the complex. 5). The Balkan complex is a kind of indicator of the growth of the newly formed crust as a result of collision and accretion processes.

scholarly journals Boninitic variolites of the Buribay volcanic complex the Southern Urals: mineralogy, geochemistry and formation conditions

LITOSFERA ◽  
2018 ◽  
Vol 18 (2) ◽  
pp. 246-279 ◽  
Author(s):  
Aleksandr M. Kosarev ◽  
◽  
Sergei A. Svetov ◽  
Svetlana Yu. Chazhengina ◽  
Gul’nara T. Shafigullina ◽  
...  
Keyword(s):  
Southern Urals ◽  
Volcanic Complex ◽  
The Southern Urals ◽  
Formation Conditions

New data on REE and rare-metal mineralization in pegmatites of the Slyudyanogorsk muscovite deposit in the Southern Urals

2016 ◽  
Vol 58 (8) ◽  
pp. 681-690
Author(s):  
V. I. Popova ◽  
V. A. Muftakhov ◽  
V. A. Popov ◽  
I. A. Blinov ◽  
V. A. Kotlyarov
Keyword(s):  
Southern Urals ◽  
Rare Metal ◽  
The Southern Urals ◽  
Rare Metal Mineralization

scholarly journals Subduction, collision and plumes in the epoch of the Late Paleozoic magmatism of the Magnitogorsk zone (the Southern Urals)

LITOSFERA ◽  
2019 ◽  
pp. 191-208
Author(s):  
D. N. Salikhov ◽  
V. V. Kholodnov ◽  
V. N. Puchkov ◽  
I. R. Rakhimov
Keyword(s):  
Late Phase ◽  
Active Continental Margin ◽  
Southern Urals ◽  
Island Arc ◽  
Late Paleozoic ◽  
Time Interval ◽  
Geochemical Type ◽  
The Southern Urals ◽  
European Continent ◽  
East European

Subject. A systematization of Late-Paleozoic magmatic formations of the Magnitogorsk zone of the Southern Urals in the process of an accretion of the Magnitogorsk paleoarc to the margin of the East European continent (EEC) with formation in Famenian and Carboniferous active continent margin of South-Uralian accretionary-collisional belt was given in the work. Materials and methods. A generalization of published and manuscript materials characterizing magmatism and ore-mineralization of Magnitogorsk zone for the Devonian-Carboniferous-Permian time carried out, additional investigations of chemical composition of rocks (XRF, ISP-MS) characterizing process of accretion, subduction and plume activity, microelement distribution in them was made, the composition of rock-forming and accessory minerals (EPMA) was studied. Results. It is found that the South-Uralian accretionary-collisional belt was beginning to form in the late phase of the development of the Magnitogorsk island arc in the process its collision with EEC margin with formation in the Frasnian and Carboniferous of active continental margin. The products of Late-island-arc volcanism are represented by the porphyrite formation and in the eastern frame of the arc - by subalkaline monzonite-shoshonite-latite volcanic-intrusive association with intermediate characteristics between the subductional and interplate formations. Synchronously with them, in the backarc setting, picrite and meymechite volcanics − derivatives of a mantle plume are formed. In process of substitution of tectonic-magmatic regime from island-arc to margin-continental intraplate-type mantle series were forming. During this period, hot asthenospheric diapirs (plumes) were rising to the bottom of new-formed (accreted) margin-continental lithosphere. Along with the magmatic associations of intraplate type and rock series of intermediate geochemical type, this geodynamic situation in the Southern Urals is characterized by a presence of great volumes of mantle-crust granitoids of gabbro-tonalite-granodiorite-granite type, that were formed with a manifold manifestation of anatexis in a time interval of 365-290 Ma. Conclusion. On the whole the originality of Magnitogorsk zone geological history in the Devonian and Carboniferous, peculiarities of magmatic complexes formed here due to various geodynamic settings, are making this zone an extraordinary interesting and important object to study of processes of plume-lithosheric and mantle-crust interaction.

Revisiting the tectonic evolution of the Triassic Palaeo-Tethys convergence zone in northern Thailand inferred from detrital zircon U–Pb ages

2020 ◽  
pp. 1-25
Author(s):  
Hidetoshi Hara ◽  
Tetsuya Tokiwa ◽  
Toshiyuki Kurihara ◽  
Thasinee Charoentitirat ◽  
Apsorn Sardsud
Keyword(s):  
Continental Margin ◽  
South China ◽  
Detrital Zircon ◽  
Active Continental Margin ◽  
Sedimentary Rocks ◽  
Convergence Zone ◽  
Accretionary Complex ◽  
Northern Thailand ◽  
Collision Zone ◽  
Back Arc

Abstract Detrital zircon U–Pb ages for sediments in and around the Palaeo-Tethyan convergence zone in northern Thailand provide constraints for tectonic interpretations of the Indochina Block, the Sibumasu Block, the Inthanon Zone accretionary complex and the Nan Back-arc Basin during the Triassic. In sedimentary rocks of the Indochina Block, almost all of the Palaeozoic and Triassic zircons were sourced from the collision zone between the Indochina and South China blocks, and an active continental margin in the western Indochina Block. Sediments of the Sibumasu Block were supplied by erosion of Archaean basement and from the Grenville and the Pan African orogenies, but show no record of Permian to Triassic igneous activity. Accretionary complex sediments have provenances of both the Sukhothai Arc and the Indochina and South China blocks, with detrital zircons of various ages being supplied from crustal uplift and erosion related to the Indosinian I orogeny. Sedimentary rocks of the Nan Back-arc Basin are widely distributed not only in the Nan–Uttaradit but also in northern Sukhothai areas. The origin of the Pha Som Metamorphic Complex and associated formations can be traced to basin-filling sediments in the Nan Back-arc Basin. These detrital zircon U–Pb ages have also allowed identification of the changing tectonic setting in the Palaeo-Tethys convergence zone from the ‘erosion of Proterozoic continental basement’ to ‘Palaeozoic active continental margin in the western Indochina Block’ and ‘Palaeozoic, Permian to Triassic collision zone between the South China and Indochina blocks’ through to ‘Triassic active Sukhothai Arc’.

scholarly journals Carboniferous continental margin mafic-ultramafic sheeted dyke complex in the West Magnitogorsk zone (Southern Urals)

2019 ◽  
pp. 42-50
Author(s):  
A. V. Ryazantsev ◽  
L. A. Novikov ◽  
A. A. Razumovskij
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Early Carboniferous ◽  
Southern Urals ◽  
Island Arc ◽  
Ultramafic Rocks ◽  
The West ◽  
Dyke Swarms

In the West of the aHochthon of Magnitogorsk zone thrusted onto the Precambrian complexes of the Uraltau zone, the Devonian island-arc complexes overlap stratigraphicalry the Ordovician and Silurian chert-basalt sequences and serpentine melange. Melange and Ordovician strata are intruded by dyke swarms and sheeted dykes («dyke in dyke») which are composed of mafic and ultramafic rocks. The dykes, composed by gabbro-dolerite, amphibole K-feldspar gabbro, hornblendite, picrite and lamprophyre, predominate. The composition of the ultramafic rocks corresponds to the composition of picrite and komatiite. The 40Ar/39Ar age of the magmatic amphibole from gabbro is 357 ± 8 m.y. The formation of dykes is related to the Early Carboniferous rift-related magmatism on an active continental margin.

scholarly journals Reconstruction of the Vendian–Cambrian active continental margin of the Southern Urals: results of studying of detrital zircon from the Ordovician terrigenous rocks

2019 ◽  
pp. 43-59
Author(s):  
A. V. Ryazantsev ◽  
N. B. Kuznetsov ◽  
K. E. Degtyarev ◽  
T. V. Romanyuk ◽  
T. Yu. Tolmacheva ◽  
...  
Keyword(s):  
East European Platform ◽  
Active Continental Margin ◽  
Southern Urals ◽  
Detrital Zircons ◽  
Passive Margin ◽  
Granitic Rocks ◽  
The Southern Urals ◽  
East European ◽  
Volcano Plutonic Belt ◽  
Plutonic Belt

Detrital zircons of Ordovician terrigenous sequences are studied in various Southern Uralian tectonic units.The age of detrital zircons of the West Uralian and Transuralian megazones, Taganai–Beloretsk Zone, and Kraka allochthons spans from the Late Archean to the end of the Vendian– beginning of the Cambrian; Early Precambrian and Early–Middle Riphean zircons are the most abundant. Vendian–Cambrian detrital zircons are strongly dominant in the Uraltau Zone, Sakmara allochthons, and East Uralian Megazone; the zircons of other ages are absent or extremely rare. The Vendian–Cambrian detrital zircons of all Southern Urals zones probably derive from volcanic and granitic rocks of the marginal continental belt, which are part of the Uraltau Zone, Sakmara allochthons, and East Uralian Megazone. The Lu–Hf isotopic characteristics of Vendian–Cambrian detrital zircons indicate that their parental rocks formed on a heterogeneous basement that includes blocks of juvenile and ancient continental crust. According to a model of the pre-Ordovician tectonic evolution of the Southern Urals, at the end of the Late Riphean, the passive margin of the East European Platform collided with a block on a heterogeneous basement. The formation of the block terminated with the Grenville Orogeny. After collision, a volcano-plutonic belt originated in the Vendian–Cambrian at the actively evolved margin of the East European Platform.

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