The paleogeodynamic conditions of redeposition of conodont elements in the late devonian-early carboniferous sediments of the Southern Urals

The Middle Devonian brachiopod genus Cyrtinoides, described from the southern Urals, is a senior subjective synonym of Mucroclipeus, previously known only from eastern and western North America. The Middle and Late Devonian cyrtinid brachiopod genus Komiella, previously known only from the Timan Range of eastern Europe, is identified from west-central Alaska and Nevada. A new family Komiellidae is proposed. New species are Komiella gilberti, K. magnasulca, and K. stenoparva. Known species of both genera occupy carbonate platform foreslope facies or shelf basins, allowing open marine migration via peripheral biofacies.

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Geology, physical-chemical and geodynamic conditions for the formation of Sokolovsk and Krasnokamensk granitoid massifs (South Ural)

Georesursy ◽

10.18599/grs.2021.1.9 ◽

2021 ◽

Vol 23 (1) ◽

pp. 85-93

Author(s):

Vladimir I. Snachev ◽

Aleksandr V. Snachev ◽

Boris A. Puzhakov

Keyword(s):

Early Carboniferous ◽

Southern Urals ◽

Geological Structure ◽

Rift System ◽

Second Phase ◽

The Southern Urals ◽

Lower Carboniferous ◽

Sedimentary Deposits ◽

Granite Formation ◽

Physical Chemical

The article describes the geological structure of the Sokolovsk and Krasnokamensk massifs located in the central part of the Western subzone of the Chelyabinsk-Adamovka zone of the Southern Urals. They are of Lower Carboniferous age and break through the volcanogenic-sedimentary deposits of the Krasnokamensk (D3kr) and Bulatovo (S1-D1bl) strata. It was found that these intrusions belong to the gabbro-syenite complex and are composed of gabbroids (phase I) and syenites, quartz monzonites, less often monzodiorites (phase II). The rocks of the second phase predominate (90–95%). Gabbros belong to the normal alkaline series of the sodium series and are close to tholeiitic mafic rocks, the formation of which is associated with riftogenic structures; syenites correspond to moderately alkaline series with K-Na type of alkalinity. It has been proved that in terms of their petrographic, petrochemical, geochemical, and metallogenic features (content of TiO2, K2O, Na2O, Rb, Sr, distribution of REE, the presence of skarn-magnetic mineralization), the rocks of the massifs under consideration undoubtedly belong to the gabbro-granite formation. Crystallization of the Sokolovsk and Krasnokamensk intrusions occurred at a temperature of 880–930 °С in the mesoabyssal zone at a depth of about 7–8 km (P = 2.2–2.4 kbar). At the postmagmatic stage, the transformation parameters of the initially igneous rocks were, respectively, T = 730–770 °C, P = 4.0–4.2 kbar. The fact that these massifs belong to the gabbro-granite formation makes it possible to include them, together with Bolshakovsk, Klyuchevsky, Kurtmaksky and Kambulatovo, into the Chelyabinsk-Adamovka segment of the South Ural Early Carboniferous rift system.

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Biostratigraphy and taxonomy of fusulinid foraminifera across the Upper Mississippian (upper Serpukhovian)–Lower Pennsylvanian (Bashkirian) successions from the Hadim Nappe, Central Taurides, southern Turkey

Journal of Paleontology ◽

10.1017/jpa.2020.116 ◽

2021 ◽

pp. 1-21

Author(s):

Melikan Akbaş ◽

Cengiz Okuyucu

Keyword(s):

New Species ◽

Shallow Water ◽

Late Cretaceous ◽

Depositional Environment ◽

Southern Urals ◽

Russian Platform ◽

Late Devonian ◽

The Southern Urals ◽

Southern Turkey ◽

Stratigraphic Succession

Abstract The Hadim Nappe, which is one of the allochthonous tectonic units in the Tauride Belt, in southern Turkey, includes a continuous stratigraphic succession from the Middle(?)–Late Devonian to Late Cretaceous. A relatively complete succession of the upper Serpukhovian to Bashkirian is exposed in the Central Taurides, where two sections (Yassıpınar and Gölbelen) have been selected for detailed biostratigraphic investigations. The Mississippian-Pennsylvanian boundary in these sections was determined by the first appearance datum of the Plectostaffella jakhensis and located in the oolitic limestone facies indicating a shallow-water depositional environment. The uppermost Serpukhovian and regional Bashkirian substages (Syuranian, Akavasian, Askynbashian, and Arkhangelskian) were determined by index taxa, namely Plectostaffella jakhensis, P. bogdanovkensis, P. varvariensis, Pseudostaffella antiqua, Staffellaeformes staffellaeformis, Tikhonovichiella tikhonovichi, and Verella spicata. Fifty fusulinid species belonging to fourteen genera were determined in two sections, in which two species are new: Depratina turani Akbaş new species and Tikhonovichiella praetikhonovichi Akbaş new species. The taxonomic positions of two fusulinid species (Depratina convoluta n. comb. and Staffellaeformes parva robusta n. comb.) are revised. The studied fusulinid assemblages correlate with fusulinid assemblages from the southern Urals, Russian Platform, Donetz Basin, Darvaz, Spain, central Iran, and some other regions of the Tethyan Realm. UUID: http://zoobank.org/bcbb6c72-f6f9-4e77-9cf9-3572bd731ff3

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Latitudes of the Eastern Ural microcontinent and Magnitogorsk island arc in the Paleozoic Ural Ocean

LITOSFERA ◽

10.24930/1681-9004-2020-20-6-842-850 ◽

2020 ◽

Vol 20 (6) ◽

pp. 842-850

Author(s):

V. S. Burtman ◽

A. V. Dvorova ◽

S. G. Samygin

Keyword(s):

Middle Devonian ◽

Volcanic Belt ◽

Early Carboniferous ◽

Southern Urals ◽

Island Arc ◽

Middle Urals ◽

The Southern Urals ◽

Tectonic Zone ◽

Middle Ordovician ◽

The Baltic

Research subject. Rocks of the Paleozoic Eastern Ural microcontinent and Magnitogorsk island arc occupy a significant part of the Southern Urals and some part of the Middle Urals. The Western Urals are composed of rocks of the ancient Baltic continent and overthrust oceanic rocks. In the Eastern Urals and Trans-Urals rocks of the accretion complexes, oceanic crust, island arcs, the Eastern Ural microcontinent and the Kazakhstan Paleozoic continent are widespread. Rocks are exposed in the Denisov tectonic zone. The Magnitogorsk simatic Island Arc originated in the Ural Ocean, near the Baltic continent, in the early Devonian, developing from the Emsian to the Famennian. A collision between the Magnitogorsk arc and the Baltic continent occurred in the Famennian century. In the pre-Carboniferous age, the Eastern Ural microcontinent was located in the Ural Ocean. In the Tournaisian period, the Eastern Ural microcontinent accreted with the Baltic continent. The Kazakhstan continental massif was located on the other side of the Ural Ocean. The volcanic belt above the subduction zone was active on the edge of the Kazakhstan continent in the Early–Middle Devonian and in the Early Carboniferous. A subduction under the Baltic and Kazakhstan continents consumed most of the crust of the Ural Ocean by the middle of the Bashkir century. As a result, the Baltic continent (together with the Eastern Ural microcontinent) came into contact with the Kazakhstan continent. The formation of folded orogen began in the Moscow century following the collision of sialic terrains.Materials and methods. The research was based on the relevant data obtained by several researchers in 2000–2018 on rock paleomagnetism. Results. The paleolatitudinal positions of the Eastern Ural microcontinent were determined, comprising 5.3 ± 7.4°) in the Middle Ordovician and 8.2 ± 7.2° in the Early–Middle Silurian. The respective paleolatitudinal positions for the Early–Middle Devonian comprised: the Ural margin of the Baltic paleocontinent (7.7 ± 3.7°), the Magnitogorsk island arc (3.2 ± 3.1°) and the Ural margin of the Kazakhstan paleocontinent (20.6 ± 3.8°).Conclusion. According to the analysed paleomagnetic data, in the Early–Middle Devonian, the distance between the latitudes of the margins of the Baltic and Kazakhstan continents was not less than 600 km provided they were in the same hemisphere, and more than 2,300 km provided they were in different hemispheres. The convergence of the terrains was associated with the subduction of the Ural Ocean crust before its closure, which occurred in the Tournaisian century.

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Laser 40Ar/39Ar ages of single detrital white mica grains related to the exhumation of Neoproterozoic and Late Devonian high pressure rocks in the Southern Urals (Russia)

Geological Magazine ◽

10.1017/s0016756803008628 ◽

2004 ◽

Vol 141 (2) ◽

pp. 161-172 ◽

Cited By ~ 11

Author(s):

A. P. WILLNER ◽

J.-A. WARTHO ◽

U. KRAMM ◽

V. N. PUCHKOV

Keyword(s):

High Pressure ◽

Southern Urals ◽

White Mica ◽

Late Devonian ◽

Chemical Compositions ◽

Age Group ◽

Formula Unit ◽

The Southern Urals ◽

Source Areas ◽

Upper Vendian

Single grains of detrital white mica from two different synorogenic sediments in the Southern Urals were analysed using the in situ ultraviolet laser ablation Ar–Ar dating technique to discriminate between age signatures associated with a high-pressure signal (phengites) from those related to muscovite only. Two disparately aged sandstone formations of Neoproterozoic (Upper Vendian) and Upper Devonian (Famennian) age were formed by the erosion of high-relief source areas with contemporaneously exhumed high-pressure rocks. A bimodal distribution of ages and chemical compositions can be detected in the two detrital populations. There is no age overlap between the two populations, reflecting completely different source areas containing high-pressure rocks of different ages. Within the Upper Vendian sandstones, detrital white mica from a 571–609 Ma age group is phengitic in composition (Si 3.3–3.41 per formula unit), while an older 645–732 Ma age group is comprised of muscovite composition grains only. The first group is compatible with the time of late exhumation and emplacement of a source area containing high-pressure rocks, the Neoproterozoic Beloretzk terrane. The older age range is compatible with a long history of cooling and the allochthonous nature of this terrane. Detrital white mica from the Famennian sandstones (Zilair Formation) comprises one age group (342–421 Ma) containing phengite (Si 3.21–3.39 per formula unit) and muscovite, and a second group (446–496 Ma) containing muscovite only. While the derivation of the second group cannot be correlated with any as yet known regional data, the first age group indicates the earliest arrival of high-pressure rocks at the surface along the suture zone after Late Devonian arc–continent collision.

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History of the formation of the early Carboniferous gabbro-granite formation, Southern and Middle Urals

Moscow University Bulletin. Series 4. Geology ◽

10.33623/0579-9406-2019-5-10-18 ◽

2019 ◽

pp. 10-18

Author(s):

A. V. Snachev ◽

V. I. Snachev ◽

M. A. Romanovskaya

Keyword(s):

Early Carboniferous ◽

Southern Urals ◽

Island Arc ◽

Middle Urals ◽

The South ◽

The Southern Urals ◽

Granite Formation ◽

History Of

The article presents new data on the geology and petrogeochemistry of the Magnitogorsk, Nepljuevsk and Kanzafarov rock complexes. Their belonging to the gabbro-granite formation has been proved. These data give opportunity to combine the South Ural and Middle Ural segments of the Early Carboniferous subduction rift into a single submeridional structure. Its formation took place at the Devonian island arc rear basin. The arc was overthrusted on the western edge of the East Ural Rise during the collision stage of the Southern Urals development. The Cu-Mo specialization of granitoids of the Magnitogorsk and Nepljuevsk complexes has been established.

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