scholarly journals Breed Associations of the Gaisin Block of the Ukrainian Shield

2021 ◽  
pp. 61-70
Author(s):  
O.V. Ziultsle ◽  
◽  
V.V. Ziultsle ◽  
Keyword(s):  
Mineral Composition ◽  
Regional Metamorphism ◽  
Granulite Facies ◽  
Ukrainian Shield ◽  
Metamorphic Rocks ◽  
Geological Surveys ◽  
Wide Range ◽  
Block Structures

The Gaysins block is characterized by a wide range of both metamorphic and ultrametamorphic formations. Ultrametamorphic formations are represented by an association of rocks with a transition from charnockitoids to two-feldspar granites. Remnants of metamorphic rocks are composed of diafluorinated varieties to varying degrees. Geological surveys of the last decades have discovered on the territory of the Gaysin block structures of variegated composition, which are represented by both metamorphic and ultrametamorphic rocks. The most studied are structures in the area of the settlements of Chagiv, Tyagun, Sitkovtsi, Naraevka, Tsibuliv and Popudnya. The wide variety of the mineral composition of the rocks of the Gaysinsky block is due to the metamorpho-metasomatic transformations of the primary parageneses formed under the conditions of the granulite facies. These transformations are taking place against the background of a decrease in the PT parameters of regional metamorphism.

scholarly journals Microscopy and Microanalysis of Magmatic and Metamorphic Minerals – Part 1: Cordierite

2008 ◽  
Vol 16 (5) ◽  
pp. 30-37 ◽  
Author(s):  
Robert Sturm
Keyword(s):  
Regional Metamorphism ◽  
Igneous Rocks ◽  
Major Constituent ◽  
Metamorphic Rocks ◽  
High Grade ◽  
Shearing Stress ◽  
The Past ◽  
Peraluminous Granites ◽  
Wide Range ◽  
Higher Temperature

Cordierite represents an orthorhombic (Mg,Fe)Al-silicate (Table 1) that is observed in a wide range of natural occurrences. As outlined in numerous mineralogical overviews published during the past decades, cordierite mainly crystallizes in thermally metamorphosed rocks, particularly in those derived from argillaceous sediments. Additionally, the mineral can be a major constituent of parageneses formed under high-grade regional metamorphism and therefore occurs in respective schists, gneisses and granulites. The metamorphic formation of cordierite is generally restricted to conditions of deficient or low shearing stress producing only moderate lithological pressures. With rising pressure due to transpression cordierite often breaks down to enstatite and sillimanite or, at higher temperature, to sapphirine and quartz (see also Fig. 5). Besides its crystallization in metamorphic rocks, cordierite is also found in specific igneous rocks like peraluminous granites and related high-grade anatectic terrains.

Zircon ages and the distribution of Archaean and Proterozoic rocks in the Rauer Islands

1993 ◽  
Vol 5 (2) ◽  
pp. 193-206 ◽  
Author(s):  
P. D. Kinny ◽  
L. P. Black ◽  
J. W. Sheraton
Keyword(s):  
Granulite Facies ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
High Grade ◽  
Ion Microprobe ◽  
Rock Interaction ◽  
Mafic Rocks ◽  
Grade Fluid ◽  
Vestfold Hills ◽  
Intrusive Suite

The application of zircon U-Pb geochronology using the SHRIMP ion microprobe to the Precambrian high-grade metamorphic rocks of the Rauer Islands on the Prydz Bay coast of East Antarctica, has resulted in major revisions to the interpreted geological history. Large tracts of granitic orthogneisses, previously considered to be mostly Proterozoic in age, are shown here to be Archaean, with crystallization ages of 3270 Ma and 2800 Ma. These rocks and associated granulite-facies mafic rocks and paragneisses account for up to 50% of exposures in the Rauer Islands. Unlike the 2500 Ma rocks in the nearby Vestfold Hills which were cratonized soon after formation, the Rauer Islands rocks were reworked at about 1000 Ma under granulite to amphibolite facies conditions, and mixed with newly generated felsic crust. Dating of components of this felsic intrusive suite indicates that this Proterozoic reworking was accomplished in about 30–40 million years. Low-grade retrogression at 500 Ma was accompanied by brittle shearing, pegmatite injection, partial resetting of U-Pb geochronometers and growth of new zircons. Minor underformed lamprophyre dykes intruded Hop and nearby islands later in the Phanerozoic. Thus, the geology of the Rauer Islands reflects reworking and juxtaposition of unrelated rocks in a Proterozoic orogenic belt, and illustrates the important influence of relatively low-grade fluid-rock interaction on zircon U-Pb systematics in high-grade terranes.

Compositional variation in the chevkinite group: new data from igneous and metamorphic rocks

2009 ◽  
Vol 73 (5) ◽  
pp. 777-796 ◽  
Author(s):  
R. Macdonald ◽  
H. E. Belkin ◽  
F. Wall ◽  
B. Baginski
Keyword(s):  
Electron Microprobe ◽  
Host Rock ◽  
Metamorphic Rocks ◽  
Compositional Variation ◽  
Temperature Range ◽  
Wide Range ◽  
Host Rocks ◽  
Cation Sites ◽  
Dominant Cation

AbstractElectron microprobe analyses are presented of chevkinite-group minerals from Canada, USA, Guatemala, Norway, Scotland, Italy and India. The host rocks are metacarbonates, alkaline and subalkaline granitoids, quartz-bearing pegmatites, carbonatite and an inferred K-rich tuff. The analyses extend slightly the range of compositions in the chevkinite group, e.g. the most MgO-rich phases yet recorded, and we report two further examples where La is the dominant cation in the A site. Patchily- zoned crystals from Virginia and Guatemala contain both perrierite and chevkinite compositions. The new and published analyses are used to review compositional variation in minerals of the perrierite subgroup, which can form in a wide range of host rock compositions and over a substantial pressure- temperature range. The dominant substitutions in the various cation sites and a generalized substitution scheme are described.

scholarly journals GRANITOIDS, RARE-METAL PEGMATITES AND Ta-Nb MINERALIZATION OF SHPOLIANO-TASHLYK ORE AREA (INGUL MEGABLOCK, UKRAINIAN SHIELD)

2018 ◽  
pp. 24-29
Author(s):  
O. Hrinchenko ◽  
S. Bondarenko ◽  
T. Mironchuk
Keyword(s):  
Rare Metal ◽  
Ukrainian Shield ◽  
Wide Range ◽  
Ore Minerals ◽  
Ore Mineralization ◽  
Isomorphic Series ◽  
Single Complex ◽  
Complex Features ◽  
First Time ◽  
Range Of Values

Composition of granites, genetically associated pegmatites and superimposed metasomatites distributed within Shpoliano-Tashlyk ore area (Ingul megablock) is considered. It is established, that on the basis of similarity in their petrographic and petrochemical features granitoids of the area can be related to single complex. Features of ore mineralization are defined by both composition of granitoids (Sgranites) after which rare-metal pegmatites are formed and intensity of superimposed metasomatic alterations. Main minerals-concentrators of Ta and Nb mineralization in granitic pegmatites and metasomatites are represented by minerals of three isomorphic series – columbite-tantalite (Fe,Mn)(Nb,Ta,Ti)2O6, ilmenorutile-struverite (Ti,Nb,Ta)O2 and pyrochlore-microlite (Ca,Na)2Ta2O6(O,B,OH,F). Depending on geological setting such ore minerals as tapiolite, ixiolite, cassiterite, uraninite, nigerite, gahnite are commonly found in association with these minerals. Chemical composion of tantalo-niobates sampled from ore-bearing pegmatites and metasomatites is investigated by microprobe analysis. Most minerals of columbite-tantalite series are characterized by distinct and rhythmic internal zonality and contrasting mosaic structure which are related to considerable heterogeneities of their chemical composition. Within one aggregate mineral phases with wide range of values – from 9,80 to 71,0 % for Ta2O5 and from 10,6 to 70,1 % for Nb2O5 – are established. Among minerals ferruginous varieties which composition relates to Fe-columbite-tantalites (Nb2O5/Ta2O5 = 1–1,2; FeO/MnO = 2,5–6) prevail. Columbite-tantalites are characterised by high contents of admixture elements present (%): TiO2 – to 5,88; WO3 – to 3,70; SnO2 – to 9,20; Sc2O3 – to 5,40. Scandium ores occur as scandium-rich minerals that are mostly confined to the minerals of columbite-tantalite series found in Polohivka ore field. On the Ukrainian Shield high contents of Sc2O3 in tantalo-niobates are established for the first time. Minerals of ilmenorutile-struverite series do not quantitatively yield to minerals of columbite-tantalite series. For minerals of this series Nb2O5/Ta2O5 ratio varies in the range of 0,6-1,4. Among characteristic admixture-elements are prevailed (%): SnO2 – to 3,1, V2O5 – to 5,05; FeO – to 11,51, Cr2O3 – to 1,20. Minerals of pyrochlore-microlite series are of subordinate importance. For the first time by results of U-Pb dating of columbite-tantalites from Mostove ore manifestation (Shpoliano-Tashlyk area) the age of Ta-Nb mineralization is established to be about 1965 ± 25 million years.

scholarly journals Zircon U–Pb Dating and Lu-Hf Isotope of the Retrograded Eclogite from Chicheng, Northern Hebei Province, China

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
Xu Kong ◽  
Xueyuan Qi ◽  
Wentian Mi ◽  
Xiaoxin Dong
Keyword(s):  
Regional Metamorphism ◽  
Granulite Facies ◽  
Amphibolite Facies ◽  
Metamorphic Event ◽  
Isotopic Data ◽  
Metamorphic Condition ◽  
Eu Anomaly ◽  
Facies Metamorphism ◽  
Eclogite Facies ◽  
Plagioclase Gneiss

We report zircon U–Pb ages and Lu-Hf isotopic data from two sample of the retrograded eclogite in the Chicheng area. Two groups of the metamorphic zircons from the Chicheng retrograded eclogite were identified: group one shows characteristics of depletion in LREE and flat in HREE curves and exhibit no significant Eu anomaly, and this may imply that they may form under eclogite facies metamorphic condition; group two is rich in HREE and shows slight negative Eu anomaly indicated that they may form under amphibolite facies metamorphic condition. Zircon Lu-Hf isotopic of εHf from the Chicheng eclogite has larger span range from 6.0 to 18.0, which suggests that the magma of the eclogite protolith may be mixed with partial crustal components. The peak eclogite facies metamorphism of Chicheng eclogite may occur at 348.5–344.2 Ma and its retrograde metamorphism of amphibolite fancies may occur at ca. 325.0 Ma. The Hongqiyingzi Complex may experience multistage metamorphic events mainly including Late Archean (2494–2448 Ma), Late Paleoproterozoic (1900–1734 Ma, peak age = 1824.6 Ma), and Phanerozoic (495–234 Ma, peak age = 323.7 Ma). Thus, the metamorphic event (348.5–325 Ma) of the Chicheng eclogite is in accordance with the Phanerozoic metamorphic event of the Hongqiyingzi Complex. The eclogite facies metamorphic age of the eclogite is in accordance with the metamorphism (granulite facies or amphibolite facies) of its surrounding rocks, which implied that the tectonic subduction and exhumation of the retrograded eclogite may cause the regional metamorphism of garnet biotite plagioclase gneiss.

Two-feldspar geothermometry in granulite facies metamorphic rocks

1977 ◽  
Vol 65 (2) ◽  
pp. 123-133 ◽  
Author(s):  
John C. Stormer ◽  
James A. Whitney
Keyword(s):  
Granulite Facies ◽  
Metamorphic Rocks

The Influence of the Mineral Composition of Alcoholic Beverages of Grape Origin on their Bottling Resistance

2021 ◽  
pp. 11-13
Author(s):  
Дарья Владиславовна Андриевская ◽  
Екатерина Владимировна Ульянова
Keyword(s):  
Mineral Composition ◽  
Alcoholic Beverages ◽  
Quantitative Composition ◽  
Group 4 ◽  
Physico Chemical ◽  
Wide Range ◽  
Additional Costs ◽  
Group 3 ◽  
Group 2 ◽  
The Stability

В настоящее время известны основные причины формирования различных видов помутнений в спиртных напитках виноградного происхождения. В значительной степени изучены компоненты образующихся при этом осадков. Вместе с тем одна из часто возникающих проблем современного производства заключается в потере стабильности продукции при транспортировании и хранении, что влечет дополнительные расходы предприятий по возврату и технологическим обработкам забракованной продукции. Целью настоящей работы стало сравнительное исследование минерального состава обработанных коньяков и их стабильности к различным видам помутнений. Объекты исследований - образцы обработанных коньяков отечественного производства, которые были разделены в зависимости от возраста на четыре группы: 1 группа - 3-летние, 4-летние и 5-летние; 2 группа - выдержанные «КВ» и выдержанные высшего качества «КВВК»; 3 группа - старые «КС», 4 группа - очень старые «ОС». На 1-м этапе было проведено исследование физико-химических и органолептических показателей продукции. В результате установлено, что все образцы соответствовали требованиям ГОСТ 31732-2014. Тесты на склонность к различным видам помутнений показали стабильность образцов к обратимым коллоидным, белковым и кальциевым помутнениям. Установлено, что качественный состав минеральных веществ обработанных коньяков различного возраста идентичен. При этом массовая концентрация отдельных компонентов варьирует в широком диапазоне. Доля образцов обработанных коньяков, в которых были превышены уровни концентраций отдельных ионов, гарантирующих стабильность продукции, составила в среднем 15%. Сравнительный анализ количественного состава катионов и анионов в обработанных коньяках дает основание предположить, что образцы с высоким содержанием ионов Са2+, Na+ и SO42- имеют высокий риск потери стабильности в дальнейшем. Таким образом, результаты проведенных исследований показали необходимость совершенствования методики определения склонности коньяков к различным видам помутнений в части расширения контролируемых показателей. Currently, the main reasons for the formation of various types of turbidity in alcoholic beverages of grape origin are known. The components of the precipitation formed during this process have been studied to a large extent. At the same time, one of the frequently occurring problems of modern production is the loss of product stability during transportation and storage, which entails additional costs for enterprises to return and process rejected products. The purpose of this work was a comparative study of the mineral composition of processed cognacs and their stability to various types of turbidity. The objects of research were samples of processed cognacs of domestic production, which were divided depending on age into four groups: group 1 - three-year-old, four-year-old and five-year-old; group 2 - aged «KV» and aged of the highest quality «KVVK»; group 3 - old «KS», group 4 - very old «OS». At the first stage, a study of the physico-chemical and organoleptic parameters of the products was carried out. As a result, it was found that all samples met the requirements of GOST 31732-2014. Tests for the propensity to various types of turbidity showed the stability of the samples to reversible colloidal, protein and calcium turbidity. It is established that the qualitative composition of the minerals of processed cognacs of different ages is identical. At the same time, the mass concentration of individual components varies in a wide range. The share of samples of processed cognacs in which the concentration levels of individual ions guaranteeing the stability of products were exceeded averaged 15%. A comparative analysis of the quantitative composition of cations and anions in processed cognacs suggests that samples with a high content of Ca2+, Na+ and SO42- ions have a high risk of loss of stability in the future. Thus, the results of the conducted studies have shown the need to improve the methodology for determining the propensity of cognacs to various types of turbidity in terms of expanding the controlled indicators.

Evolution of geodynamics since the Archean: Significant change at the dawn of the Phanerozoic

Geology ◽  
2020 ◽  
Vol 48 (5) ◽  
pp. 488-492 ◽  
Author(s):  
M. Brown ◽  
C.L. Kirkland ◽  
T.E. Johnson
Keyword(s):  
Ultrahigh Pressure ◽  
Secular Change ◽  
Metamorphic Rocks ◽  
Data Sets ◽  
Ultrahigh Pressure Metamorphism ◽  
Slab Breakoff ◽  
Wide Range ◽  
O Isotope ◽  
Global Data Sets ◽  
Global Data

Abstract A time-series analysis of thermobaric ratios (temperature/pressure [T/P]) for Paleoarchean to Cenozoic metamorphic rocks identified significant shifts in mean T/P that may be related to secular change in the geodynamics on Earth. Thermobaric ratios showed significant (>95% confidence) change points at 1910, 902, 540, and 515 Ma, recording drops in mean T/P, and at 1830, 604, and 525 Ma, recording rises in mean T/P. Highest mean T/P occurred during the Mesoproterozoic, and lowest mean T/P occurred from the Cambrian to the Oligocene. Correlated changes were seen between T/P and global data sets of time-constrained hafnium (Hf) and oxygen (O) isotope compositions in zircon. The range of correlated variation in T/P, Hf, and O was larger during the formation of Rodinia than Columbia. Large changes and a wide range for these variables continued through the Phanerozoic, during which a statistically significant 83 m.y. frequency of T/P excursions recorded the high tempo of orogenic activity associated with the separation, migration, and accretion of continental terranes during the formation of Pangea. Since the early Tonian, the decreasing mean T/P of metamorphism, widespread appearance of blueschist and ultrahigh-pressure metamorphism, and wide fluctuations in Hf and O isotope compositions document a change to the modern plate-tectonic regime, characterized by widespread continental subduction and deeper slab breakoff than in the Proterozoic.

The Facies Classification of Metamorphic Rocks

1924 ◽  
Vol 61 (4) ◽  
pp. 167-170 ◽  
Author(s):  
C. E. Tilley
Keyword(s):  
Mineral Composition ◽  
Metamorphic Rocks ◽  
Independent Variables ◽  
Temperature Conditions ◽  
Facies Classification ◽  
Two Independent Variables

The diversity in mineral composition of metamorphic rocks can be regarded as the resultant of two independent variables, first of the ultimate composition of the rocks, and secondly of the grade of metamorphism, or the particular pressure-temperature conditions under which the rocks have arisen. It is clear that these two variables may well form the basis of a classification of rocks of metamorphic origin.

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