scholarly journals GEOLOGY OF CARBONACEOUS DEPOSITS OF THE BIRGILDA STRATA (EAST URAL TROUGH)

2021 ◽  
Author(s):  
А.V. Snachev ◽  
◽  
K.R. Nurieva ◽  
R.R. Islamov ◽  
◽  
...  
Keyword(s):  
Regional Metamorphism ◽  
Geological Structure ◽  
Black Shales ◽  
Greenschist Facies ◽  
Igneous Rocks ◽  
Exothermic Effect ◽  
Low Carbon ◽  
Temperature Range ◽  
Carbonaceous Deposits

The article describes the geological structure of the Birgilda strata, which is widely developed in the East Ural trough. It is shown that the Birgilda black shales, which contain Corg in the range of 0.5–2.7% (average 1.3%), are of the low-carbon type. The exothermic effect in them occurred mainly in the temperature range 570–660 ° С, which corresponds to the greenschist facies of regional metamorphism. On the A-S-C diagram, the rocks of the Birgilda strata are approximately equally scattered over the carbonate-carbonaceous and siliceous-carbonaceous fields and noticeably less in the terrigenous-carbonaceous fields. The Birgilda sequence is characterized by a collisional environment of accumulation and products of destruction of mainly basic igneous rocks.

On the possible analogy between the Dizi Series of the Southern slope zone of the Greater Caucasus and the folded basement of the plain Crimea: composition, metamorphism, magmatism and age

2021 ◽  
Author(s):  
Irakli Javakhishvili ◽  
David Shengelia ◽  
Tamara Tsutsunava ◽  
Giorgi Chichinadze ◽  
Giorgi Beridze ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Regional Metamorphism ◽  
Geological Structure ◽  
Greenschist Facies ◽  
Igneous Rocks ◽  
Contact Metamorphism ◽  
Southern Slope ◽  
Quartz Syenite ◽  
Greater Caucasus ◽  
Geological Conditions

<p>The Dizi Series is exposed within the Southern slope zone of the Greater Caucasus that occurs as a complex geological structure, which constitutes an integral part of the Mediterranean (Alpine-Himalayan) collisional orogenic belt. It is built up of terrigenous and volcanogenic-sedimentary rocks faunistically dated from the Devonian to Triassic inclusive (Somin, 1971; Somin, Belov, 1976; Kutelia 1983). Most of them are metamorphosed under conditions of chlorite-sericite subfacies of the greenschist facies of regional metamorphism (chlorite-phengite-albite±quartz, graphite-sericite-quartz phyllites and marbleized limestones), and only a minor part represented by clay-carbonaceous, phengite-chlorite-carbonaceous and prehnite-chlorite-carbonate schists underwent anchimetamorphism (Shengelia et al., 2015). The Dizi Series is intruded by numerous magmatic bodies of gabbro-diabases, diabases, diorites, diorite-porphyries, syenites, monzo-syenites and granitoids. The age of the intrusions was defined by K-Ar method at 176-165 Ma (Dudauri, Togonidze, 1998) and by U-Pb LA-ICP-MS zircon dating at 166.5 ± 4.6 Ma (authors` unpublished data) and corresponds to the Bathonian orogeny. The Middle Jurassic intrusions caused intense contact metamorphism of the rocks of the Dizi Series resulted in the formation of various hornfelses containing andalusite, cordierite, corundum, biotite, plagioclase, potassium feldspar, clinozoisite, hornblende, cummingtonite, clinopyroxene, wollastonite and scapolite. These rocks correspond to albite-epidote-hornfels, andalusite-biotite-muscovite-chlorite-hornfels and andalusite-biotite-muscovite-hornfels subfacies of the contact metamorphism (Javakhishvili et al., 2020). The analogues of the Dizi Series rocks have not previously been established either in the Greater Caucasus or in the neighboring regions. In our view, Paleozoic rocks similar to the Dizi Series occur under the Cretaceous and Jurassic deposits within the folded basement of the plain Crimea where they were recovered by wells. Most of these rocks, as in the Dizi Series, underwent metamorphism of chlorite subfacies of the greenschist facies and, to a lesser extent, deep epigenesis (clayey-carbonaceous, sericite-carbonaceous, actinolite-chlorite-prehnite, muscovite-albite-chlorite, epidote-actinolite-chlorite and graphite-talc-quartz schists) (Chernyak, 1969). These rocks are also intruded by Middle Jurassic igneous rocks, including gabbro-diabases, diabases, diorites, syenites, monzo-syenites, granite-porphyries, etc. (Shniukova, 2016; Shumlyanskyy, 2019). As a result of the contact metamorphism of the basement rocks, muscovite-quartz-cordierite and cordierite-quartz-feldspar micaceous hornfelses were formed. Quartz syenite yielded a K-Ar age of 158 Ma (Scherbak, 1981), while monzo-syenite was dated at 170 ± 5 Ma applying 40Ar/39Ar method (Meijers, 2010). Thus, based on the rock associations, the nature of metamorphism, the age of the metamorphic and igneous rocks, and on the spatial position of the Dizi Series and folded basement of the plain Crimea we assume that these units developed coevally in similar environment and geological conditions.<br><br>Acknowledgements.This work was supported by Shota Rustaveli National Science Foundation (SRNSF) [PHDF-19-159, Regional and Contact Metamorphism of the Dizi Series].</p>

Geology, formation conditions, and ore content of the Turgoyak granite massif and carbonaceous deposits of its western framing (South Ural)

2020 ◽  
pp. 12-20
Author(s):  
A. V. Snachev ◽  
V. I. Snachev ◽  
M. A. Romanovskaya
Keyword(s):  
Black Shale ◽  
Regional Metamorphism ◽  
Geological Structure ◽  
Amphibolite Facies ◽  
Contact Metamorphism ◽  
Granite Massif ◽  
Carbonaceous Deposits ◽  
Local Areas ◽  
Formation Conditions ◽  
Granitoid Massif

The article describes the geological structure of the Turgoyak granitoid massif (γϬС1–2ts), Urenga (RF2ur) and Uytash (RF3uš) suites. In the Late Vendian time the rocks first experienced regional metamorphism under the conditions of the cummingtonite-amphibolite facies at a temperature of 550–595 °C and a pressure of 250400 МПа, and then in local areas — diaftoresis (T=520530 °C and P=130170 МПа). During the formation of the Turgoyak massif (T=770810 °C and P=210250 МПа), the rocks of the Urengin and Uytash suites were subjected to contact metamorphism. This metamorphic processes made the black shale gold to remove from the black shale zone of the amphibole-hornfels facies and caused its redeposition within the albite-epidote-hornfly zone.

scholarly journals Evaluation of induced residual stresses on AISI 1020 low carbon steel plate from experimental and FEM approach during TIG welding process

2019 ◽  
Vol 13 (1) ◽  
pp. 4415-4433
Author(s):  
I. B. Owunna ◽  
A. E. Ikpe
Keyword(s):  
Carbon Steel ◽  
Residual Stresses ◽  
Steel Plate ◽  
Low Carbon Steel ◽  
Welding Process ◽  
Service Condition ◽  
Tig Welding ◽  
Von Mises Stress ◽  
Low Carbon ◽  
Temperature Range

Induced residual stresses on AISI 1020 low carbon steel plate during Tungsten Inert Gas (TIG) welding process was evaluated in this study using experimental and Finite Element Method (FEM). The temperature range measured from the welding experimentation was 251°C-423°C, while the temperature range measured from the FEM was 230°C-563°C; whereas, the residual stress range measured from the welding experimentation was 144MPa-402Mpa, while the residual range measured from the FEM was 233-477MPa respectively. Comparing the temperature and stress results obtained from both methods, it was observed that the range of temperature and residual stresses measured were not exactly the same due to the principles at which both methods operate but disparities between the methods were not outrageous. However, these values can be fed back to optimization tools to obtain optimal parameters for best practices.  Results of the induced stress distribution was created from a static study where the thermal results were used as loading conditions and it was observed that the temperature increased as the von-Mises stress increased, indicating that induced stresses in welded component may hamper the longevity of such component in service condition. Hence, post-weld heat treatment is imperative in order to stress relieve metals after welding operation and improve their service life.

The Genesis of Oligoclase in Certain Schists

1933 ◽  
Vol 70 (12) ◽  
pp. 529-541 ◽  
Author(s):  
F. J. Turner
Keyword(s):  
Chemical Composition ◽  
Bulk Composition ◽  
Regional Metamorphism ◽  
Slight Modification ◽  
Igneous Rocks ◽  
Calcic Plagioclase ◽  
Irregular Distribution ◽  
Thermal Metamorphism

The mineralogical changes in green schists and related quartzofelspathic schists of sedimentary origin are discussed, and the following conclusions are reached as to the conditions of formation of oligoclase in these rocks:—(1) Oligoclase normally appears as a product of dynamothermal metamorphism at relatively high grades such as prevail in the zones of almandine and perhaps kyanite. It is accompanied either by deeply-coloured hornblende, hornblende and biotite, or biotite and muscovite, according to the chemical composition of the rocks in which it occurs.(2) Sodic oligoclase containing 10 per cent to 15 per cent of anorthite may occur with pale aluminous hornblende in green schists lying within the more strongly metamorphosed portion of the chlorite zone. The rocks in question are low in potash and have been formed by reconstitution, at a higher grade, of chlorite-epidotealbite-schists containing calcite. This oligoclase-hornblende association is not to be confused with the actinolite-epidote-albite-chlorite assemblage which is formed at any grade within the zone of chlorite, by direct reconstitution of basic igneous rocks without change in bulk composition and in the absence of CO2. A slight modification of Tilley’s subdivision of the green schist facies of Eskola is therefore introduced.(3) A zone of oligoclase representing a grade of metamorphism higher than that attained in the biotite zone, may be recognized for quartzo-felspathic schists of appropriate composition and for many green schists, in areas of progressive regional metamorphism. In the latter case, blue-green hornblende often accompanied by biotite is also present.(4) Oligoclase or more calcic plagioclase and deeply-coloured hornblende form readily during purely thermal metamorphism of only medium grade in the absence of stress. This accounts for the irregular distribution of both these minerals in districts where purely thermal and regional metamorphism have both occurred during the same period of orogeny.

TETGAR_C: a three-dimensional (3D) provenance plot and calculation tool for detrital garnets

2020 ◽  
Author(s):  
Wolfgang Knierzinger ◽  
Michael Wagreich ◽  
Eun Young Lee
Keyword(s):  
Three Dimensional ◽  
Greenschist Facies ◽  
Amphibolite Facies ◽  
Igneous Rocks ◽  
Source Rocks ◽  
Accurate Assessment ◽  
Potential Source ◽  
Metaigneous Rocks ◽  
Silicate Rocks

<p>We present a new interactive MATLAB-based visualization and calculation tool (TETGAR_C) for assessing the provenance of detrital garnets in a four-component (tetrahedral) plot system (almandine–pyrope–grossular–spessartine). The chemistry of more than 2,600 garnet samples was evaluated and used to create various subfields in the tetrahedron that correspond to calc-silicate rocks, felsic igneous rocks (granites and pegmatites) as well as metasedimentary and metaigneous rocks of various metamorphic grades. These subfields act as reference structures facilitating assignments of garnet chemistries to source lithologies. An integrated function calculates whether a point is located in a subfield or not. Moreover, TETGAR_C determines the distance to the closest subfield. Compared with conventional ternary garnet discrimination diagrams, this provenance tool enables a more accurate assessment of potential source rocks by reducing the overlap of specific subfields and offering quantitative testing of garnet compositions. In particular, a much clearer distinction between garnets from greenschist-facies rocks, amphibolite-facies rocks, blueschist-facies rocks and felsic igneous rocks is achieved. Moreover, TETGAR_C enables a distinction between metaigenous and metasedimentary garnet grains. In general, metaigneous garnet tends to have higher grossular content than metasedimentary garnet formed under similar P–T conditions.</p>

Petrogenesis of spilite and keratophyre from a Permian and Triassic volcanic arc terrane, eastern Oregon and western Idaho, U.S.A.

1978 ◽  
Vol 15 (8) ◽  
pp. 1356-1369 ◽  
Author(s):  
T. L. Vallier ◽  
Rodey Batiza
Keyword(s):  
Mass Balance ◽  
Ion Mobility ◽  
Regional Metamorphism ◽  
Greenschist Facies ◽  
Amphibolite Facies ◽  
Internal Mass ◽  
Volcanic Arc ◽  
Sea Floor ◽  
General Internal ◽  
Low Potassium

Spilite, keratophyre, and quartz keratophyre from a Permian and Triassic volcanic arc assemblage in eastern Oregon and western Idaho originally were low-potassium basalt, andesite, dacite, and possibly rhyolite. Amphibolite from an abyssal sea floor or marginal basin environment of either Permian or Triassic age originally was low-potassium basalt. Present mineralogies are characteristic of the greenschist and amphibolite facies of regional metamorphism. Greenschist facies minerals are mostly albite, epidote, chlorite, calcite, and quartz, whereas amphibolite facies minerals are predominantly hornblende, plagioclase (andesine), and epidote. In the volcanic arc assemblage, mineralogies of the Permian rocks are nearer equilibrium in the greenschist facies than those of the overlying Triassic rocks, probably reflecting deeper burial. Bulk compositions indicate extensive ion mobility, but there has been a general internal mass balance of most components. Na2O, CO2, and H2O were probably added to most rocks, but the source of those components has not been established.

Texture of Oxide Scales during Hot Rolling of Low Carbon Steel

2005 ◽  
Vol 495-497 ◽  
pp. 339-344 ◽  
Author(s):  
Vladimir V. Basabe ◽  
Jerzy A. Szpunar
Keyword(s):  
Carbon Steel ◽  
Oxide Scale ◽  
Hot Rolling ◽  
Low Carbon Steel ◽  
Cube Texture ◽  
Experimental Results ◽  
Oxide Scales ◽  
Low Carbon ◽  
Air Velocity ◽  
Temperature Range

The textures of oxide scales grown on low carbon steel in air over the temperature range 850-950°C were investigated. The low carbon steel was oxidized with the air velocity of 4.2 cm/s for 10 s in order to approximate the formation of tertiary scales in hot rolling. At 850°C, the wüstite texture and magnetite texture are weak with no dominant components. For the temperatures of 900 and 950°C, the wüstite and magnetite phases have a cube texture {001}<100>. The experimental results indicate that during hot rolling in the g region, the texture of the oxide scale is cubic and when rolling in the a region, the texture of the oxide scale is weak with no dominant components.

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