REE minerály fenitů čistecko-jesenického masivu (Česká republika)

2021 ◽  
Vol 29 (2) ◽  
pp. 297-320
Author(s):  
Jaromír Tvrdý ◽  
Zdeněk Dolníček ◽  
Jana Ulmanová ◽  
Ondřej Krátký ◽  
Michal Nekl
Keyword(s):  
Chemical Composition ◽  
Mineral Assemblage ◽  
Hydrothermal Activity ◽  
Tetrad Effect ◽  
Metasomatic Alteration ◽  
Mineral Phase ◽  
Material Source ◽  
Rock Types ◽  
Ree Patterns ◽  
Different Levels

Alkaline metasomatites (fenites) originated by pervasive Na metasomatism of granitoids of the Čistá-Jesenice Pluton (belonging to the Teplá-Barrandian unit in the NW part of the Bohemian Massif) contain a rich association of REE-bearing minerals. The occurrence of REE carbonates (bastnäsite, parisite), monazite, rhabdophane, churchite, fergusonite and pyrochlore was found in relatively weakly altered rocks (typical fenites), whereas much richer assemblage was observed in rocks which underwent the strongest metasomatism (so called reomorphic cancrinite-nepheline syenites). Here, the mineral assemblage includes in addition to all above mentioned minerals also xenotime and REE silicates, including tritomite/melanocerite, allanite, perbøeite, gadolinite and a Mn-analogue of hingganite. A common mineral phase is zircon in these rocks, too. Cerium, yttrium, and to lesser extent also lanthanum are dominating cations in the studied REE phases. A total of 24 mineral species was identified, including three unnamed phases. In most of the studied phases, the level of fractionation of REEs is high, exceptionally even extreme. Chondrite-normalized REE patterns of some phases are characterized by a pronounced M-type tetrad effect. The results of microprobe analyses suggest that individual minerals originated during several episodes, characterized by different chemical composition of the mineral-forming medium (especially with contrasting concentrations of strong REE-complexing ligands and oxygen fugacity) and/or temperature. We did not find any significant differences in chemistry of individual minerals present in various rock types showing different levels of metasomatic alteration. The obtained data are consistent with hydrothermal origin of most (if not all) reported REE-bearing phases. The material source and genesis of the studied REE+Nb+Zr mineralization was in all probability associated with hydrothermal activity in the exocontact of a deep-seated hypothetical carbonatite intrusion, as was suggested already in earlier works dealing with these remarkable rocks.

Petrological and geochemical characterization of the arc-related Suru–Thasgam ophiolitic slice along the Indus Suture Zone, Ladakh Himalaya

2021 ◽  
pp. 1-20
Author(s):  
I.M. Bhat ◽  
T. Ahmad ◽  
D.V. Subba Rao ◽  
N.V. Chalapathi Rao
Keyword(s):  
Suture Zone ◽  
Secondary Mineral ◽  
High Field Strength ◽  
Geochemical Characterization ◽  
Rock Types ◽  
Ladakh Himalaya ◽  
Magnesian Olivine ◽  
Textural Relationship ◽  
Ree Patterns

Abstract The Ladakh Himalayan ophiolites preserve remnants of the eastern part of the Neo-Tethyan Ocean, in the form of Dras, Suru Valley, Shergol, Spongtang and Nidar ophiolitic sequences. In Kohistan region of Pakistan, Muslim Bagh, Zhob and Bela ophiolites are considered to be equivalents of Ladakh ophiolites. In western Ladakh, the Suru–Thasgam ophiolitic slice is highly dismembered and consists of peridotites, pyroxenites and gabbros, emplaced as imbricate blocks thrust over the Mesozoic Dras arc complex along the Indus Suture Zone. The Thasgam peridotites are partially serpentinized with relict olivine, orthopyroxene and minor clinopyroxene, as well as serpentine and iron oxide as secondary mineral assemblage. The pyroxenites are dominated by clinopyroxene followed by orthopyroxene with subordinate olivine and spinel. Gabbros are composed of plagioclase and pyroxene (mostly replaced by amphiboles), describing an ophitic to sub-ophitic textural relationship. Geochemically, the studied rock types show sub-alkaline tholeiitic characteristics. The peridotites display nearly flat chondrite-normalized rare earth element (REE) patterns ((La/Yb)N = 0.6–1.5), while fractionated patterns were observed for pyroxenites and gabbros. Multi-element spidergrams for peridotites, pyroxenites and gabbros display subduction-related geochemical characteristics such as enriched large-ion lithophile element (LILE) and depleted high-field-strength element (HFSE) concentrations. In peridotites and pyroxenites, highly magnesian olivine (Fo88.5-89.3 and Fo87.8-89.9, respectively) and clinopyroxene (Mg no. of 93–98 and 90–97, respectively) indicate supra-subduction zone (SSZ) tectonic affinity. Our study suggests that the peridotites epitomize the refractory nature of their protoliths and were later evolved in a subduction environment. Pyroxenites and gabbros appear to be related to the base of the modern intra-oceanic island-arc tholeiitic sequence.

scholarly journals Effect of shoot topping intensity on 'Cabernet Franc' grapevine maturity in high-altitude region

2017 ◽  
Vol 52 (10) ◽  
pp. 946-950
Author(s):  
Douglas André Würz ◽  
José Luiz Marcon Filho ◽  
Alberto Fontanella Brighenti ◽  
Ricardo Allebrandt ◽  
Betina Pereira de Bem ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Leaf Area ◽  
Soluble Solids ◽  
Anthocyanin Content ◽  
Total Polyphenol ◽  
Cabernet Franc ◽  
Grape Berries ◽  
Grape Quality ◽  
Vegetative Canopy ◽  
Different Levels

Abstract: The objective of this work was to evaluate the chemical composition of 'Cabernet Franc' grape subjected to different levels of shoot topping. The experiment was conducted in the 2008 and 2009 vintages, and the levels of shoot topping consisted of: control, without topping; and reductions of 15, 30, and 45% in total leaf area. The effect of shoot topping intensity on the chemical composition of the 'Cabernet Franc' grape berries was observed. A reduction of 26% in the vegetative canopy through a moderate shoot topping increased the total polyphenol index and the anthocyanin content. Shoot topping is a practice that must be carried out with caution, since severe shoot topping, i.e., a reduction greater than 26% of the leaf area, may negatively impact grape quality by reducing the content of soluble solids and decreasing the total polyphenol index and the content of anthocyanins of 'Cabernet Franc' grape berries.

scholarly journals Discrimination of Genealogical Groups of Arabica Coffee by the Chemical Composition of the Beans

2019 ◽  
Vol 11 (16) ◽  
pp. 141
Author(s):  
Larissa O. Fassio ◽  
Marcelo R. Malta ◽  
Gladyston R. Carvalho ◽  
Antônio A. Pereira ◽  
Ackson D. Silva ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Chemical Composition ◽  
Chemical Markers ◽  
Total Lipids ◽  
Germplasm Bank ◽  
Total Sugars ◽  
Coffee Beans ◽  
Different Levels ◽  
Important Marker

This work aimed to characterize and discriminate genealogical groups of coffee as to the chemical composition of the grains through the model created by PLS-DA method. 22 accessions of Coffea arabica, from the Active Germplasm Bank of Minas Gerais, were divided into groups according to the genealogical origin. Samples of ripe fruits were harvested selectively and processed by the wet method, to obtain pulped coffee beans, with 11% (b.u.) of water content. The raw beans were assessed as to the content of polyphenols, total sugars, total lipids, protein, caffeine, sucrose, and fatty acids. The data were submitted the chemometric analysis, PCA and PLS-DA. The results of PLS-DA identified the variables which most influence the classification of genealogical groups and possible chemical markers to accessions processed by the pulped method. The sucrose content was an important marker for the Exotic accession group. However, the content of polyphenols has been identified as a marker for the group Tymor Hybrid, and the caffeine for the bourbon group. The different fatty acids have been identified as markers for all genealogical groups, at different levels. The model PLS-DA is effective in discriminating genealogical groups from the chemical composition of the beans.

scholarly journals Eclogite-like rocks from Southern Pirin Mountains – preliminary results about petrology and time of formation

2021 ◽  
Vol 82 (3) ◽  
pp. 61-63
Author(s):  
Lyubomirka Macheva ◽  
Philip Machev ◽  
Rossitsa Vassilevа ◽  
Yulia Plotkina
Keyword(s):  
Mineral Assemblage ◽  
Late Jurassic ◽  
Mineral Chemistry ◽  
Metasomatic Alteration ◽  
Preliminary Results ◽  
Icp Ms ◽  
Geological Map ◽  
Host Rocks ◽  
The Village

North-northeast of the village of Ilinden (Southern Pirin Mnt.) three eclogite boudins were separated on the geological map in scale 1:50 000 (Sarov, 2010). The rocks belong to the Slasten lithotectonic unit. The mineral assemblage and mineral chemistry do not allow these rocks to be classified as eclogites. They can be considered as eclogite-like ones, formed by postmagmatic-metasomatic alteration of the host rocks. Based on LA-ICP-MS sphene U-Pb dating, eclogite-like rocks yield a Late Jurassic age (160±19 Ma).

A rare free silica-bearing micrometeorite

2021 ◽  
Author(s):  
Dafilgo Fernandes
Keyword(s):  
Mineral Assemblage ◽  
Frictional Heating ◽  
Upper Atmosphere ◽  
Carbonaceous Chondrites ◽  
Mineral Phase ◽  
Unique Type ◽  
Free Silica ◽  
System A ◽  
The Earth ◽  
Cosmic Spherules

<p>Extraterrestrial dust that reaches the Earth’s surface has shown to represent the diverse types of samples from different precursors, namely, asteroid complexes and cometary bodies from the solar system. A substantial amount of this dust that strikes the upper atmosphere is believed to have been lost due to frictional heating with air molecules. Cosmic spherules that are melted particles are some of the widely recognized micrometeorites that survived this catastrophic entry process; however, their primordial characteristics are altered from their precursors making it difficult to identify the precursors. An individual peculiar spherule MS-I35-P204 recovered from the Antarctica blue ice has been identified. The spherule has been segregated using magnetic separation method, mounted in epoxy, and examined using SEM, subsequently analysed under electron microprobe. It is surrounded by a thin magnetite rim, and also holds a single kamacite bead that protrudes out at its top. The interior mineralogy mostly constitutes of a bulk pyroxene normative glass (MnO>2wt%) with several vesicles. The rare mineral phase is a skeletal aggregate of free silica, bearing Fe nuggets embedded in a glass. An isolated narrow lath of forsterite appears to be chondritic and is observed as relict grain that is associated with an anomalous low Ca pyroxene (MnO ~1.3 wt%, FeO~13 wt%). Earlier, free silica has been reported in some chondritic meteorites particularly the Enstatite and Ordinary group, and also in some carbonaceous chondrites such as CM, CR, CH, and K. It profoundly forms a pod that encloses the ferromagnesian silicate in silica-bearing chondrules. The unusual mineral assemblage seen in this spherule thereby appears to constrain probably the unique type of its contributor which need to be studied.</p>

Serpentinization at the Rainbow and Saldanha sites, Mid-Atlantic Ridge: Mineralogical, geochemical, and isotopic features

2019 ◽  
Vol 57 (5) ◽  
pp. 677-706
Author(s):  
Isabel Ribeiro da Costa ◽  
Frederick Joseph Wicks ◽  
Fernando J.A.S. Barriga
Keyword(s):  
Upper Mantle ◽  
Hydrothermal Activity ◽  
Isotopic Data ◽  
Geochemical Characterization ◽  
Textural Evolution ◽  
Mantle Peridotites ◽  
Carbonate Deposition ◽  
Mid Atlantic Ridge ◽  
Ree Patterns

Abstract The Rainbow hydrothermal field (36°14′N) and the Saldanha seamount (36°34′N), in the Mid-Atlantic Ridge (MAR), are tectonic exposures of serpentinized upper mantle peridotites, both associated with significant hydrothermal activity. On the basis of detailed mineralogical and geochemical characterization of serpentinites from both sites, several serpentinization-related issues are discussed in the present work. As expected in oceanic environments, most of the sampled rocks are lizardite-chrysotile serpentinites exhibiting a variety of pseudomorphic through non-pseudomorphic textures, such textural evolution probably being related to changing water/rock ratios during this retrograde process. Oxygen isotope temperatures indicate that the serpentinization took place at 300–200 °C; on the other hand, isotopic data suggest that replacement of early pseudomorphic lizardite by lizardite ± chrysotile non-pseudomorphic textures requires that temperatures and/or water/rock ratios are high enough to promote the necessary dissolution–recrystallization processes. Mass-balance calculations for olivine-serpentine and orthopyroxene-serpentine pairs provided a basis for establishing serpentinization reactions likely to have produced the present rocks. Moreover, these calculations also showed that, notwithstanding some noticeable loss of MgO from olivine and of SiO2 from orthopyroxene, serpentinization of both minerals implies volume increases on the order of 26–27%, therefore potentially promoting the overall expansion of the rock. The geochemical and isotopic features of the studied rocks indicate that unmodified seawater was responsible for the serpentinization of the MAR peridotites. However, the mineralogy and REE patterns of some of these serpentinites indicate occasional subsequent interaction of the serpentinized rocks with seawater at much lower temperatures (seafloor alteration, characterized by carbonate deposition and negative Ce anomalies), or with high-temperature ore-forming hydrothermal fluids (ore-forming alteration, characterized by sulfide precipitation and steep positive Eu anomalies).

Essential oil content and chemical composition of Cymbopogon citratus inoculated with arbuscular mycorrhizal fungi under different levels of lead

2015 ◽  
Vol 76 ◽  
pp. 734-738 ◽  
Author(s):  
Caroline Lermen ◽  
Fabrício Morelli ◽  
Zilda Cristiani Gazim ◽  
Adriana Pereira da Silva ◽  
José Eduardo Gonçalves ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Essential Oil ◽  
Arbuscular Mycorrhizal Fungi ◽  
Mycorrhizal Fungi ◽  
Oil Content ◽  
Arbuscular Mycorrhizal ◽  
Cymbopogon Citratus ◽  
Different Levels

Nutritional assessment of beetroot (Beta vulgaris L.) powder cookies

2017 ◽  
Vol 36 (03) ◽  
Author(s):  
Murlidhar Ingle ◽  
S. S. Thorat ◽  
P. M. Kotecha ◽  
C. A. Nimbalkar
Keyword(s):  
Chemical Composition ◽  
Beta Vulgaris ◽  
Cardiovascular Health ◽  
Nutritional Assessment ◽  
Ash Content ◽  
Crude Fibre ◽  
Nutritional Qualities ◽  
Physical And Chemical ◽  
Sodium And Potassium ◽  
Different Levels

uits and vegetables are important constituents of the diet and provide significant quantities of nutrients, especially vitamins, minerals and fiber. Beetroots (Beta vulgaris L.) are a rich source of potent antioxidants and minerals including magnesium, sodium and potassium. It contains betaine, which is important for cardiovascular health. Beetroots are low in calories (about 45 Kcal per 100 g) and have zero cholesterol. The study was conducted to improve the nutritional qualities of cookies with incorporation of different levels of beetroot powder i.e. 0, 5, 7, 10, 15 and 20 %, and examined for its physical and chemical composition. The proximate composition of cookies enriched with beetroot powder from 5 to 20% indicated that protein was increased from 7.39 to 9.12 %, crude fibre 0.95 to 1.90 % and ash content 0.93 to1.89 %. The incorporation of beetroot powder in cookies lowered the lightness (L*) and yellowness (b*) but increased redness (a*) of cookies. The hardness of the cookies was increased with increasing the level of beetroot powder. Sensory evaluation of cookies concluded that the cookies prepared with addition of 10% beetroot powder were more acceptable as compared to others.

Application of chlorite thermometry to estimation of formation temperature and redox conditions

Clay Minerals ◽  
2018 ◽  
Vol 53 (2) ◽  
pp. 143-158 ◽  
Author(s):  
Atsuyuki Inoue ◽  
Sayako Inoué ◽  
Minoru Utada
Keyword(s):  
Chemical Composition ◽  
Formation Process ◽  
Mineral Assemblage ◽  
Geothermal Field ◽  
Present Approach ◽  
Redox Conditions ◽  
Data Sets ◽  
Formation Temperature ◽  
Semi Empirical

ABSTRACTDiverse applications of chlorite thermometry have been considered for better understanding the formation process in nature. Here, an approach which combined a semi-empirical thermometer (Inoueet al.,2009) with the method of Walshe (1986) was tested to estimate the redox conditions (logfO2) and the formation temperature, using the literature data from Niger, Rouez and St Martin and new data for chlorite which coexists with pink-coloured epidote in the Noboribetsu geothermal field. The logfO2predicted for the former data sets were compatible with those estimated by Vidalet al.(2016), suggesting that the present approach is valid for quantifying the variations in logfO2. The Noboribetsu chlorites have lower Fe/(Fe + Mn + Mg) and greater Fe3+/ΣFe ratios than those observed in adjacent propylite rocks. The peculiar mineral assemblage and chemical composition are attributed to the formation under higherfO2conditions and possibly low Fe concentration in the alteration fluids.

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