Igneous layering in a dacite: on the origin and significance of Layer Cake Mountain, Kelowna, B.C., Canada

1998 ◽  
Vol 62 (6) ◽  
pp. 731-742 ◽  
Author(s):  
J. D. Greenough ◽  
J. V. Owen
Keyword(s):  
Major Elements ◽  
Fault Scarp ◽  
Thin Layers ◽  
Magma Chambers ◽  
Mafic Lava ◽  
Land Form ◽  
Layer Cake ◽  
Small Primary ◽  
Thick Layers ◽  
Igneous Layering

AbstractA Tertiary, dacitic volcanic land-form in Kelowna, British Columbia, shows layering that has not been recognized elsewhere. Layering is expressed as thin (0.5 m) layers separated by thick (4.5 m) layers exposed along a weathered fault scarp. The major elements show that both thick and thin layers are dacitic and geochemically very similar. Trace element modelling indicates that thin layers formed from thick layers via crystal fractionation involving removal of plagioclase, biotite and magnetite in the proportions 75:20:5, and with only 12% fractionation. The thin layers represent segregation veins generated during crystallization of the dacite. They formed when the crystal mush at the bottom of the upper crust successively, thermally contracted, fractured and foundered, siphoning evolved interstitial liquid from the mush into the horizontal crack. Cooling of the segregation veins led to further fracturing. Later, fluids following these fractures altered the thin layers and precipitated secondary carbonate minerals. The altered thin layers weather preferentially, thus visually accentuating the small primary chemical differences between thick and thin layers. The scale of layering, mode of formation and differentiation mechanisms appear different from those in felsic magma chambers and it is unclear how common this phenomenon is. However, similar layering is more easily identified and commonly developed in mafic lava flows.

scholarly journals Vulcânicas potássicas intemperizadas como protólitos dos filitos hematíticos da Serra do Espinhaço Meridional (Minas Gerais)

2020 ◽  
Vol 34 (2) ◽  
pp. 183-194
Author(s):  
Alexandre Chaves ◽  
Luiz Knauer
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Volcanic Rocks ◽  
Alkaline Rock ◽  
Major Elements ◽  
Volcanic Origin ◽  
Espinhaço Range ◽  
Weathering Processes ◽  
Igneous Layering ◽  
Hematitic Phyllite

The hematitic phyllite is a rock that occurs in the São João da Chapada and Sopa-Brumadinho formations of the southern Espinhaço range. Its origin is widely discussed in papers on Espinhaço, but there is no consensus on its protolith due to certain characteristics of the lithotype, such as its chemical composition and textural features. The pattern of rare earth elements strongly enriched [(La/Yb)N 6.80-17.68], with light rare earth elements [(La/Sm)N 2.54-4.83] richer than heavy ones [(Gd/Yb)N 1.28-3,32], suggests that the protolith was an alkaline volcanic rock formed during the rift that generated the Espinhaço basin. The major elements indicate that the alkaline rock met weathering processes, becoming a regolith. During the Brasiliano metamorphism, it finally became hematitic phyllite. Other characteristics of the lithotype, such as the presence of sericite-bearing rounded parts (possibly formed by alteration and deformation of leucite crystals) and the preservation of igneous layering, suggest a potassic volcanic origin for hematitic phyllite. In diagram that allows identifying altered and metamorphic volcanic rocks, the investigated samples have composition similar to a feldspathoid-rich alkali-basalt, probably a leucite tephrite, a leucitite or even a lamproite, rocks from mantle source.

Igneous Layering in Basaltic Magma Chambers

2015 ◽  
pp. 75-152 ◽  
Author(s):  
O. Namur ◽  
Bénédicte Abily ◽  
Alan E. Boudreau ◽  
Francois Blanchette ◽  
John W. M. Bush ◽  
...  
Keyword(s):  
Basaltic Magma ◽  
Magma Chambers ◽  
Igneous Layering

Stability of Nanometer-Thick Layers in Hard Coatings

MRS Bulletin ◽  
2003 ◽  
Vol 28 (3) ◽  
pp. 169-172 ◽  
Author(s):  
Scott A. Barnett ◽  
Anita Madan ◽  
Ilwon Kim ◽  
Keith Martin
Keyword(s):  
High Temperature ◽  
Elevated Temperatures ◽  
Temperature Stability ◽  
Hexagonal Wurtzite Structure ◽  
Thin Layers ◽  
Hard Coatings ◽  
High Temperature Stability ◽  
The Stability ◽  
Hardness Values ◽  
Thick Layers

AbstractThis article reviews two topics related to the stability of hard coatings composed of nanometer-thick layers: epitaxial stabilization and high-temperature stability. Early work on nanolayered hard coatings demonstrated large hardness increases as compared with monolithic coatings, but it was subsequently found that the layers interdiffused at elevated temperatures. More recently, it has been shown that nanolayers exhibit good stability at elevated temperatures if the layer materials are thermodynamically stable with respect to each other and are able to form low-energy coherent interfaces. This article discusses metal/nitride, nitride/nitride, and nitride/boride nanolayers that exhibit good high-temperature stability and hardness values that are maintained (or even increase) after high-temperature annealing. Epitaxial stabilization of nonequilibrium structuresin thin layers is a well-known phenomenon that has been applied to hard nitride materials. In particular, AlN, which crystallizes in the hexagonal wurtzite structure in bulk form, was stabilized in the rock-salt cubic structure in nitride/nitride nanolayers (e.g., AlN/TiN). These results and the current understanding of epitaxial stabilization in hard nanolayers are discussed.

scholarly journals Radar cross sections for mesospheric echoes at Jicamarca

2009 ◽  
Vol 27 (7) ◽  
pp. 2675-2684 ◽  
Author(s):  
G. A. Lehmacher ◽  
E. Kudeki ◽  
A. Akgiray ◽  
L. Guo ◽  
P. Reyes ◽  
...  
Keyword(s):  
Cross Sections ◽  
Isotropic Turbulence ◽  
Solar Proton ◽  
Thin Layers ◽  
Turbulence Theory ◽  
Homogeneous Isotropic Turbulence ◽  
Radar Cross Sections ◽  
Order Of Magnitude ◽  
Summer Echoes ◽  
Thick Layers

Abstract. Radar cross sections (RCS) of mesospheric layers at 50 MHz observed at Jicamarca, Peru, range from 10−18 to 10−16 m−1, three orders of magnitudes smaller than cross sections reported for polar mesospheric winter echoes during solar proton events and six orders of magnitude smaller than polar mesospheric summer echoes. Large RCS are found in thick layers around 70 km that also show wide radar spectra, which is interpreted as turbulent broadening. For typical atmospheric and ionospheric conditions, volume scattering RCS for stationary, homogeneous, isotropic turbulence at 3 m are also in the range 10−18 to 10−16 m−1, in reasonable agreement with measurements. Moreover, theory predicts maximum cross sections around 70 km, also in agreement with observations. Theoretical values are still a matter of order-of-magnitude estimation, since the Bragg scale of 3 m is near or inside the viscous subrange, where the form of the turbulence spectrum is not well known. In addition, steep electron density gradients can increase cross-sections significantly. For thin layers with large RCS and narrow spectra, isotropic turbulence theory fails and scattering or reflection from anisotropic irregularities may gain relevance.

Evolution of Drag Folds

1963 ◽  
Vol 100 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Hans Ramberg
Keyword(s):  
Shear Strain ◽  
Dynamic Theory ◽  
Fluid Dynamic ◽  
Compressive Strain ◽  
Thin Layers ◽  
Monoclinic Symmetry ◽  
Thick Layers ◽  
Theory And Experiments

AbstractTheory and experiments show that a component of compressive strain parallel to layering is necessary to develop drag folds. The component of shear strain needed for the monoclinic symmetry of such folds is not sufficient to form the wavy pattern. Based upon fluid dynamic theory and experiments with layered rubber slabs it is suggested that drag folds on flanks of major folds generally evolve as follows: Layer-parallel compression of more or less straight layered rocks causes some layers to shorten essentially by more or less uniform compressive strain and thickening (thick and not-so-competent layers), other layers to shorten essentially by buckling (thin and most component layers). In the course of time, however, the rate of buckling of the thick layers becomes significant relative to the rate of arc-shortening, and the thin layers with the early formed short buckles are forced to mimic the larger folds of the thick layers more or less passively. In this process the early formed short buckles become tilted and assume the typical drag-fold shape.

scholarly journals Low-energy electron transmission for the analysis of the interface barrier formation and the density of the unoccupied electronic states in the ultra-thin layers of fluorinated copper-phthalocyanine

2015 ◽  
Vol 3 (1) ◽  
Author(s):  
A. S. Komolov ◽  
E. F. Lazneva ◽  
S. N. Akhremtchik ◽  
N. B. Gerasimova ◽  
S. A. Pshenichnyuk
Keyword(s):  
Copper Phthalocyanine ◽  
Electronic States ◽  
Thin Layers ◽  
Low Energy ◽  
Interfacial Structure ◽  
Electron Transmission ◽  
Barrier Formation ◽  
Interface Barrier ◽  
Low Energy Electron ◽  
Thick Layers

AbstractThe interfacial structure made from the thermally deposited 5 – 7 nm thick layers of hexadecafluoro copper phthalocyanine (F

Infrared Emission Spectroscopy. I. Basic Considerations

1972 ◽  
Vol 26 (1) ◽  
pp. 73-76 ◽  
Author(s):  
Peter R. Griffiths
Keyword(s):  
High Pressure ◽  
Emission Spectroscopy ◽  
Infrared Emission ◽  
Thin Layers ◽  
Surface Films ◽  
Silicone Grease ◽  
Basic Principles ◽  
Ir Emission ◽  
Thick Layers

The basic principles behind the characterization of compounds by ir emission spectroscopy have been illustrated using surface films of silicone grease and gaseous samples. Anomalous features in the spectra are accounted for by considering the absorption of emitted radiation by less thermally excited molecules in the path to the detector. It is suggested that ir emission spectroscopy can be used easily to characterize thin layers on heated specular mirrors or hot vapors at low pressure, but care must be taken in the interpretation of results for thick layers of gases at high pressure, when the temperature of the emitter is close to that of the detector, or when molecules are to be characterized on substrates whose emissivity is high.

ON MODELS FOR VISCOELASTIC MATERIALS THAT ARE MECHANICALLY INCOMPRESSIBLE AND THERMALLY COMPRESSIBLE OR EXPANSIBLE AND THEIR OBERBECK–BOUSSINESQ TYPE APPROXIMATIONS

2013 ◽  
Vol 23 (10) ◽  
pp. 1761-1794 ◽  
Author(s):  
VÍT PRUŠA ◽  
K. R. RAJAGOPAL
Keyword(s):  
Viscoelastic Fluid ◽  
Boussinesq Approximation ◽  
Polymer Processing ◽  
Thin Layers ◽  
Type Approximation ◽  
Buoyancy Driven Flows ◽  
Small Temperature Gradient ◽  
Basic Ideas ◽  
Thermal Stimuli ◽  
Thick Layers

Viscoelastic fluid like materials that are mechanically incompressible but are compressible or expansible with respect to thermal stimuli are of interest in various applications ranging from geophysics and polymer processing to glass manufacturing. Here we develop a thermodynamical framework for the modeling of such materials. First we illustrate the basic ideas in the simpler case of a viscous fluid, and after that we use the notion of natural configuration and the concept of the maximization of the entropy production, and we develop a model for a Maxwell type viscoelastic fluid that is mechanically incompressible and thermally expansible or compressible. An important approximation in fluid mechanics that is frequently used in modeling buoyancy driven flows is the Oberbeck–Boussinesq approximation. Originally, the approximation was used for studying the flows of viscous fluids in thin layers subject to a small temperature gradient. However, the approximation has been used almost without any justification even for flows of non-Newtonian fluids induced by strong temperature gradients in thick layers. Having a full system of the governing equations for a Maxwell type viscoelastic mechanically incompressible and thermally expansible or compressible fluid, we investigate the validity of the Oberbeck–Boussinesq type approximation for flows of this type of fluids. It turns out that the Oberbeck–Boussinesq type approximation is in general not a good approximation, in particular if one considers "high Rayleigh number" flows. This indicates that the Oberbeck–Boussinesq type approximation should not be used routinely for all buoyancy driven flows, and its validity should be thoroughly examined before it is used as a mathematical model.

scholarly journals Features of the Metallization Influence on Phase Velocities of Acoustic Waves in Piezoelectric Plates

2019 ◽  
pp. 718-727
Author(s):  
Olga P. Zolotova ◽  
Sergey I. Burkov
Keyword(s):  
Elastic Wave ◽  
Acoustic Waves ◽  
Metal Layer ◽  
Thin Layers ◽  
Sensitivity Curve ◽  
Sh Waves ◽  
Phase Velocities ◽  
Displacement Vectors ◽  
Metal Layers ◽  
Thick Layers

The paper presents an analysis of the influence of the load represented by two metal layers on the change in the phase velocity of the dispersion modes of the elastic Lamb and SH-waves in "Me/ZnO/Me" and "Me/AlN/Me" structures depending on the elastic wave frequency and the ratio of the metal layer to the piezoelectric layer thickness. Aluminum (Al), molybdenum (Mo) and platinum (Pt) are considered as the metal layer materials (Me). Only the elastic Lamb wave modes have localized maxima of the sensitivity curve S for all types of structures. Systems with low values of acoustic impedances for layers and plates materials have maximum values of S for metallization with thin layers, and also have minimal differences in the profiles of the components of the displacement vectors of the elastic wave. Systems with the most different values of acoustic impedances of layers and plates materials have maximum values of S when metallized with thick layers, and also have maximum differences in the profiles of the components of the displacement vectors of the elastic wave. PACS: 43.25.Fe; 43.35.Cg; 77.65.-j

scholarly journals Origin of quartzo-feldspathic supracrustal rocks from the central part of the Nagssugtoqidian Mobile Belt of West Greenland

1984 ◽  
Vol 117 ◽  
pp. 1-26
Author(s):  
A Rehkopff
Keyword(s):  
Granulite Facies ◽  
Major Elements ◽  
Thin Layers ◽  
Mobile Belt ◽  
Calc Alkaline ◽  
Rock Types ◽  
Metavolcanic Rocks ◽  
The Individual ◽  
Metaigneous Rocks ◽  
Discrimination Methods

The Marranguit-Kangilerssua supracrustals constitute a sequence of variable supracrustallithologies intensely folded into surrounding orthogneisses and metamorphosed under granulite facies conditions. No field or petrographic evidence indicates the original nature of the individual supracrustal rock types. Fortynine samples from the quartzo-feldspathic part of the supracrustals have been analysed for major elements and the trace elements Cr, Co, Ni, Cu, Zn, Rb, Sr, Zr and Ba. Ten different geochemical discrimination methods indicate that both metasedimentary and metaigneous material are present. The metaigneous rocks possess typical calc-alkaline differentiation trends and were originally extrusives. Mixing-zones between metasedimentary and metavolcanic material are interpreted as reflecting a pyroclastic nature of some of the metavolcanic rocks. The quartzo-feldspathic part of the M-K supracrustals is dominated by greywacke/lithic arenite with subordinate intercalations of mudstone and single layers or lensoid bodies of subarkose and sublithic arenite. The greywacke/lithic arenite grade into calc-alkaline pyroclastics, which vary in composition from rhyodacite to rhyolite. Associated quartz-andesitic and dacitic extrusives occur throughout the supracrustal formation, which in addition contains thin layers af limestone, basic and ultrabasic rocks. The supracrustals may be either Archaean or Proterozoic in age.

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