scholarly journals Melilite-olivine neрhelinites of Mt. Tabaat (Makhtesh Ramon, Israel): Geological, petrographic and geochemical characteristics and conditions of genesis

LITOSFERA ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 323-348
Author(s):  
Z. A. Yudalevich ◽  
V. A. Vapnik ◽  
M. D. Vishnyakova ◽  
N. S. Borodina
Keyword(s):  
Melt Inclusions ◽  
Olivine Basalt ◽  
Stoichiometric Composition ◽  
Fluid Pressure ◽  
Peripheral Zone ◽  
Plastic State ◽  
High Water Content ◽  
Electron Beam Current ◽  
Special Role ◽  
Subvolcanic Body

Research subject. The melilite-olivine nephelinite subvolcanic body Tabaat, which includes melilite rocks found for the first time on the territory of Levant.Materials and methods. The chemical composition of minerals (about 400 analyzes) was determined out on a CAMECA SX-100 microanalyzer equipped with five wave spectrometers with crystal analyzers TAP, LPET and LLIF. The elemental composition was measured at an accelerating voltage of 15 kV, an electron beam current of 40 nA. The oxygen concentration was calculated from the condition of stoichiometric composition of silicate minerals and chromite. In addition, the results of earlier studies of minerals (150 analyses) and data on melt inclusions were used.Results. The Tabaat subvolcanic body, which is part of the Early Cretaceous olivine-basalt-basanite-nephelinite association Makhtesh Ramona (Negev, Israel), has a complex concentrically-zonal structure, with olivine melanephelinites in the peripheral zone, melilite-olivine melanephelinites in the central and connecting zones normative and, less often, melilite-containing melanephelinites. Prismatic separation is widely manifested in the rocks. The fold-like bending and concave-curved edges of the prisms are a reflection of the plastic state of the cooling body and its ability to compress and accommodate a high fluid pressure, which develops during the formation of melilite nephelinites.Conclusion. All mineral diversity of rocks of the Mt. Tabaat is a derivative of a single portion of magmatic melt under conditions of its adiabatic cooling at the place of stabilization. A special role in the course of crystallization of the massif belongs to minerals with a high water content – analcime, zeolites, iddingsites, bowlingites and saponite-celadonites, which indicate the deuteric stage of its development. The study of melt inclusions in olivine and clinopyroxene showed the continuity of their composition with the composition of host melilite nephelinites and the importance of incongruent melting during the formation of melilite, which is a product of the reaction of nepheline with olivine or clinopyroxene.

scholarly journals Periodically Released Magmatic Fluids Create a Texture of Unidirectional Solidification (UST) in Ore-Forming Granite: A Fluid and Melt Inclusion Study of W-Mo Forming Sannae-Eonyang Granite, Korea

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 888
Author(s):  
Jung Hun Seo ◽  
Yevgeniya Kim ◽  
Tongha Lee ◽  
Marcel Guillong
Keyword(s):  
Melt Inclusions ◽  
Melt Inclusion ◽  
Early Stage ◽  
Fluid Pressure ◽  
Unidirectional Solidification ◽  
Magmatic Fluid ◽  
Stability Field ◽  
Fluid Loss ◽  
Melt And Fluid Inclusions ◽  
Magmatic Fluids

The Upper Cretaceous Sannae-Eonyang granite crystallized approximately 73 Ma and hosted the Sannae W-Mo deposit in the west and the Eonyang amethyst deposit in the east. The granite contained textural zones of miarolitic cavities and unidirectional solidification texture (UST) quartz. The UST rock sampled in the Eonyang amethyst mine consisted of (1) early cavity-bearing aplitic granite, (2) co-crystallization of feldspars and quartz in a granophyric granite, and (3) the latest unidirectional growth of larger quartz crystals with clear zonation patterns. After the UST quartz was deposited, aplite or porphyritic granite was formed, repeating the prior sequence. Fluid and melt inclusions occurring in the UST quartz and quartz phenocrysts were sampled and studied to understand the magmatic-hydrothermal processes controlling UST formation and W-Mo mineralization in the granite. The composition of melt inclusions in the quartz phenocrysts suggested that the UST was formed by fractionated late-stage granite. Some of the melt inclusions occurring in the early-stage UST quartz were associated with aqueous inclusions, indicating fluid exsolution from a granitic melt. Hypersaline brine inclusions allowed the calculation of the minimum trapping pressure of 80–2300 bars. Such a highly fluctuating fluid pressure might be potentially due to a lithostatic-hydrostatic transition of pressure-attending fluid loss during UST formation. Highly fluctuating lithostatic-hydrostatic pressures created by fluid exsolution allowed shifting of the stability field from a quartz-feldspar cotectic to a single-phase quartz. The compositions of brine fluid assemblages hosted in the quartz phenocrysts deviated from the fluids trapped in the UST quartz, especially regarding the Rb/Sr and Fe/Mn ratios and W and Mo concentrations. The study of melt and fluid inclusions in the Eonyang UST sample showed that the exsolution of magmatic fluid was highly periodic. A single pulse of magmatic fluids of variable salinities/densities might have created a single UST sequence, and a new batch of magmatic fluid exsolution would be required to create the next UST sequence.

Elaboration and realization of new approaches to diagnostic and control of blast furnace heat

2020 ◽  
Vol 76 (2) ◽  
pp. 123-131 ◽  
Author(s):  
Yu. S. Semenov
Keyword(s):  
Blast Furnace ◽  
Effective Means ◽  
Peripheral Zone ◽  
Stream Temperature ◽  
Pulverized Coal ◽  
Plastic State ◽  
Charge Materials ◽  
Wide Range ◽  
Bof Slag ◽  
Furnace Height

Under conditions of unstable supply of quality charge materials and technological fuel, the elaboration of new effective means of blast furnace heat control becomes actual for reaching acceptable technical and economic indices of its operation. Results of the studies carried out at the BF No. 3 of Enakievo steel-works (EMZ, Ukraine) during the period from October 2011 until December 2016 presented. During the period, various fuel additives to the blast were used within a wide range of their variation, and composition of charge materials was characterized by numerous components and variable quality. In the charge content, various additives were used: iron ore, limestone, BOF slag, briquettes of pellets siftings, manganese-containing additives. The new approach to the selection of rational charging programs was justified, providing stable economic BF running under variation of heat technological conditions. For the first time the temperature indices of estimation of gas stream distribution along the furnace radius were elaborated, the rational ranges of their variation at the operation under various gas-dynamic and fuel conditions determined, requirements to the gas stream temperature distribution along the furnace radius formulated. Based on analysis of information about lining temperature along the furnace height over the five year of EMZ BF No. 3 running, its values were ascertained, showing the partial or complete lining wear in the middle and upper part of the shaft. For the lining of the furnace bottom and other parts the temperature was ascertained, showing the formation in the lower zone unstable protective scull, as well the temperature characterizing its complete absence. The influence of blast mode during addition into it an increased volume of steam, natural gas and pulverized coal on variation of distribution of peripheral gas stream temperature along the furnace height from the tuyere zone to the top studied. It became a reason for an elaboration a method of the identification of the viscous-plastic state zone border in the peripheral zone of the furnace. Regulations of the blowing-in of blast furnaces after a long time stoppage without tapping the emergency hot metal elaborated. The technology of usage manganese-containing materials in the BF charge adjusted, which demonstrated the most effective washing out of the hearth under conditions of low and unstable charge materials quality and pulverized coal injection.

Crust-mantle systems of magmatic complexes of Sikhote-Alin' (Far East, Russia)

2020 ◽  
Author(s):  
Nina Gorelikova ◽  
Nikolay Bortnikov ◽  
Aleksandr Khanchuk ◽  
Valeriy Gonevchuk ◽  
Irina Chizhova ◽  
...  
Keyword(s):  
Melt Inclusions ◽  
Regional Distribution ◽  
Crustal Contamination ◽  
Orogenic Belt ◽  
Geochemical Data ◽  
High Water Content ◽  
Crustal Material ◽  
Sikhote Alin ◽  
Margin Setting ◽  
Transform Margin

<p>Geochemical, isotope-geochemical, geochronolochical and thermobarometric study showed that the Badzhal, Mayo-Chan and Kavalerovo zones from Sikhote-Alin-Northern Sakhalin orogenic belt comprise: (1) oldest and geochemically and isotopically distinctive alkali mafic rocks, whose formation was related to mantle (asthenospheric) diapir. The possible regional distribution of the diapir is likely marked by subalkaline rocks (monzonites) having mantle Sr (0,7050) and Nd (0,5125) isotopic compositions at the Central (Tigrinoe deposit) and Southern (Kavalerovo district) Sikhote-Alin; (2) Tin-bearing ore-magmatic systems of the studied zones at the “ore region” level have similar intricate multi-root structure of generation area. 3) Magmatic evolution accompanying by increasing ore-bearing potential results in the final appearance of Li-F granites in the Badzhal Complex, and tourmaline granites in the Silinka Complex of the Myao-chan zone (Gonevchuk, 2002).</p><p>The elevated F and Cl contents and high water content as parameters responsible for ore potential of melt were confirmed by thermobarometric data (Bortnikov et al, 2019). Some associations of fluid and melt inclusions indicate that magma crystallization was accompanied by degassing with exsolution of water-rich fluids, which is required to form ore bodies in OMS. These data confirm significant role of mantle in the formation of the Myao-Chan and Badzhal zones, as well as early cassiterite—stannite—sulfide stage of the Arsen’evskoe deposit of the Kavalerovo district.</p><p>Numerical simulation of granitoids of the studied zones performed using logical-information method by I.A. Chizhova (2010) confirms crustal-mantle nature of magmatic complexes formed under transform continental margin and subduction settings. These systems are characterized by different geochemical features, in particular, different proportions of high-field strength (Sc, Y, Zr, Hf, Pb, U, Th, Nb), REE, and siderophile (Co, Ni, Cr, V, Cu) elements.</p><p>Obtained results in combination with previous data indicate that the Badzhal, Myao-Chain, and Kavalerovo zones were formed through several episodes of the growth and reworking of the Sikhote Alin’ Mesozoic continental crust, which were triggered by underplating. Granitoids and genetically related tin—base metal deposits were formed at final stage. The revealed difference in Sr-Nd composition of the granitoids could be caused by both initial geochemical crustal heterogeneity and the different degree of crustal contamination.</p><p>Geochemical and isotopic characteristics of the studied granitoids show that they were mainly derived through melting of juvenile metamafic crust, with subordinate contribution of metasedimentary rocks.</p><p>The ore-bearing magmatic complexes were formed during a change of transform margin setting by accretion of Early Cretaceous terranes of the Sikhote Alin—North Sakhalin orogenic belt.</p><p>Observed petrogeochemical diversirty of the granitoids from different zones could be caused by variations of sedimentary material, as well as by contamination of magmas by upper crustal material during emplacement, different contribution of mantle source, and diverse mechanisms of mantle-crustal interaction (Khanchuk et al, 2019). </p><p>Obtained petrochemical, geochemical, and isotopic-geochemical data on the granitoids from the studied zones provide better understanding of diversity of tin-bearing magmatism and conditions of magma generation and evolution in transform margin setting at the continent-ocean boundary.</p><p> </p>

Characterization of Rare-Earth Fluoride Anti-Stokes Phosphors by Scanning arid Transmission Electron Microscopy

1971 ◽  
Vol 29 ◽  
pp. 142-143
Author(s):  
N. M. P. Low ◽  
L. E. Brosselard
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Elevated Temperatures ◽  
Stoichiometric Composition ◽  
Rare Earth Ions ◽  
Crystalline Solid ◽  
Precipitation Process ◽  
Rare Earth Fluoride ◽  
Earth Fluoride ◽  
Rare Earth Fluorides

There has been considerable interest over the past several years in materials capable of converting infrared radiation to visible light by means of sequential excitation in two or more steps. Several rare-earth trifluorides (LaF3, YF3, GdF3, and LuF3) containing a small amount of other trivalent rare-earth ions (Yb3+ and Er3+, or Ho3+, or Tm3+) have been found to exhibit such phenomenon. The methods of preparation of these rare-earth fluorides in the crystalline solid form generally involve a co-precipitation process and a subsequent solid state reaction at elevated temperatures. This investigation was undertaken to examine the morphological features of both the precipitated and the thermally treated fluoride powders by both transmission and scanning electron microscopy.Rare-earth oxides of stoichiometric composition were dissolved in nitric acid and the mixed rare-earth fluoride was then coprecipitated out as fine granules by the addition of excess hydrofluoric acid. The precipitated rare-earth fluorides were washed with water, separated from the aqueous solution, and oven-dried.

The Ordered Phase Formation in Ti-Al-Ga Alloys

1970 ◽  
Vol 28 ◽  
pp. 440-441
Author(s):  
Shiro Fujishiro ◽  
Harold L. Gegel
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
Titanium Alloys ◽  
Growth Kinetics ◽  
Stoichiometric Composition ◽  
Good Potential ◽  
Alpha Titanium ◽  
Cold Rolled ◽  
Kinetics Of ◽  
Thermal Stability Of

Ordered-alpha titanium alloys having a DO19 type structure have good potential for high temperature (600°C) applications, due to the thermal stability of the ordered phase and the inherent resistance to recrystallization of these alloys. Five different Ti-Al-Ga alloys consisting of equal atomic percents of aluminum and gallium solute additions up to the stoichiometric composition, Ti3(Al, Ga), were used to study the growth kinetics of the ordered phase and the nature of its interface.The alloys were homogenized in the beta region in a vacuum of about 5×10-7 torr, furnace cooled; reheated in air to 50°C below the alpha transus for hot working. The alloys were subsequently acid cleaned, annealed in vacuo, and cold rolled to about. 050 inch prior to additional homogenization

Backscattered Electron Imaging of GaAs/AlGaAs Super Lattice Structures with an Ultra-High- Resolution SEM

1988 ◽  
Vol 46 ◽  
pp. 204-205
Author(s):  
Kazumichi Ogura ◽  
Michael M. Kersker
Keyword(s):  
High Resolution ◽  
Layer Structure ◽  
High Sensitivity ◽  
Beam Current ◽  
Electron Beam Current ◽  
Lattice Structures ◽  
Super Lattice ◽  
Different Types ◽  
Backscattered Electron ◽  
Electron Imaging

Backscattered electron (BE) images of GaAs/AlGaAs super lattice structures were observed with an ultra high resolution (UHR) SEM JSM-890 with an ultra high sensitivity BE detector. Three different types of super lattice structures of GaAs/AlGaAs were examined. Each GaAs/AlGaAs wafer was cleaved by a razor after it was heated for approximately 1 minute and its crosssectional plane was observed.First, a multi-layer structure of GaAs (100nm)/AlGaAs (lOOnm) where A1 content was successively changed from 0.4 to 0.03 was observed. Figures 1 (a) and (b) are BE images taken at an accelerating voltage of 15kV with an electron beam current of 20pA. Figure 1 (c) is a sketch of this multi-layer structure corresponding to the BE images. The various layers are clearly observed. The differences in A1 content between A1 0.35 Ga 0.65 As, A1 0.4 Ga 0.6 As, and A1 0.31 Ga 0.69 As were clearly observed in the contrast of the BE image.

Tensile Failure of 55-Nitinol Wire

1975 ◽  
Vol 33 ◽  
pp. 46-47
Author(s):  
F. I. Grace
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Stoichiometric Composition ◽  
Tensile Failure ◽  
Initial State ◽  
Initial Shape ◽  
Nitinol Wire ◽  
Cscl Type ◽  
Shear Transformation

An interest in NiTi alloys with near stoichiometric composition (55 NiTi) has intensified since they were found to exhibit a unique mechanical shape memory effect at the Naval Ordnance Laboratory some twelve years ago (thus refered to as NITINOL alloys). Since then, the microstructural mechanisms associated with the shape memory effect have been investigated and several interesting engineering applications have appeared.The shape memory effect implies that the alloy deformed from an initial shape will spontaneously return to that initial state upon heating. This behavior is reported to be related to a diffusionless shear transformation which takes place between similar but slightly different CsCl type structures.

TEM studies of solid-state reactions in sputter-deposited Nb/Al multilayer thin films

1996 ◽  
Vol 54 ◽  
pp. 1020-1021
Author(s):  
F. Ma ◽  
S. Vivekanand ◽  
K. Barmak ◽  
C. Michaelsen
Keyword(s):  
Thin Films ◽  
Solid State ◽  
Stoichiometric Composition ◽  
Analytical Electron Microscopy ◽  
Grain Structure ◽  
Solid State Reactions ◽  
Multilayer Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sputter Deposited

Solid state reactions in sputter-deposited Nb/Al multilayer thin films have been studied by transmission and analytical electron microscopy (TEM/AEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). The Nb/Al multilayer thin films for TEM studies were sputter-deposited on (1102)sapphire substrates. The periodicity of the films is in the range 10-500 nm. The overall composition of the films are 1/3, 2/1, and 3/1 Nb/Al, corresponding to the stoichiometric composition of the three intermetallic phases in this system.Figure 1 is a TEM micrograph of an as-deposited film with periodicity A = dA1 + dNb = 72 nm, where d's are layer thicknesses. The polycrystalline nature of the Al and Nb layers with their columnar grain structure is evident in the figure. Both Nb and Al layers exhibit crystallographic texture, with the electron diffraction pattern for this film showing stronger diffraction spots in the direction normal to the multilayer. The X-ray diffraction patterns of all films are dominated by the Al(l 11) and Nb(l 10) peaks and show a merging of these two peaks with decreasing periodicity.

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