Silicate Mineralogy of the Middle Zone Cumulates and Associated Gabbroic Rocks from the Insch Intrusion, NE Scotland

1988 ◽  
Vol 52 (366) ◽  
pp. 309-322 ◽  
Author(s):  
W. J. Wadsworth
Keyword(s):  
Principal Components ◽  
Intermediate Position ◽  
Middle Zone ◽  
Lower Zone ◽  
Fine Grained ◽  
Geographical Variations ◽  
Mineral Compositions ◽  
Complex Relationships ◽  
A Minor ◽  
Block Faulting

AbstractThe Middle Zone (MZ) of the Insch intrusion lies in a geographically intermediate position between the Lower Zone (LZ) and Upper Zone (UZ) cumulate sequences, but is more complicated than either in comprising two intricately associated, but texturally distinct, components, the MZ cumulates and the fine-grained granular gabbros (FGG). In addition, there is a minor group of porphyritic granular gabbros (PGG), containing abundant plagioclase phenocrysts. A further variety of gabbroic rock, namely quartz-biotite norite (QBN) occupies a similarly intermediate position in the Boganclogh extension of the main Insch mass. These principal components (MZ cumulates, FGG, and QBN) show considerable mineralogical overlap with each other and with the lower part of the UZ succession (UZa). Unlike the UZ rocks, they are essentially olivine-free (apart from the most basic granular gabbros) and consist mainly of plagioclase, orthopyroxene, and Ca-rich clinopyroxene, with accessory Fe-Tioxides and minor interstitial biotite and/or hornblende. Mineral compositions are in the range An70–55 (plagioclase), En71–44 (opx), and Ca46Mg42Fe12 to Ca45Mg30Fe25 (cpx), but in detail each rock group can be characterized mineralogically as well as texturally. It is concluded that the MZ cumulates and FGG (including PGG) are essentially complementary, formed in different locations, and under slightly different conditions, but in the same magma chamber. The complex relationships between them, and the apparently haphazard geographical variations in mineral compositions, may be the combined results of the magmatic events, possibly including the movement of large xenolithic fragments, and later block faulting. The substantial compositional overlap of the more evolved MZ cumulates by UZa is explained in terms of replenishment by magma of slightly more primitive (and potentially olivine-bearing) composition after the deposition of the MZ. The Boganclogh QBN is believed to represent a more hydrous fraction of the Insch MZ magma.

Hardness Evolution and High Temperature Mechanical Properties of Laser Welded DP980 Steel Joints

2018 ◽  
Vol 37 (6) ◽  
pp. 587-595
Author(s):  
Zhandong Wan ◽  
Wei Guo ◽  
Qiang Jia ◽  
Lang Xu ◽  
Peng Peng
Keyword(s):  
Yield Strength ◽  
Energy Absorption ◽  
Base Metal ◽  
Welded Joint ◽  
Dynamic Strain ◽  
Minor Effect ◽  
Fiber Laser Welding ◽  
Fine Grained ◽  
High Temperature Mechanical Properties ◽  
A Minor

AbstractDP980 steels were joined using fiber laser welding. The welded joint was characterized in terms of hardness distribution and tensile behavior at room temperature, 150 ℃, and 300 ℃, respectively. The fine-grained martensite in supercritical heat affected zone (HAZ) resulted in the highest hardness (428 Hv), while the tempered martensite contributed to the hardness decreasing (‒31 Hv). Both the ultimate tensile strength and yield strength of the base metal and welded joint decreased at 150 ℃, and then increased at 300 ℃ due to dynamic strain aging (DSA). The welded joint exhibited slightly higher yield strength and lower elongation at all the test temperatures compared to base metal due to the hardened fusion zone. The energy absorption reduced slightly with increasing temperature both for base metal and welded joint, and the weld posed a minor effect on the energy absorption. Deformation was one of the requirements for DSA effect. DSA enhanced the hardness of base metal (+78 Hv) and softened zone (+53 Hv). HAZ was not softened enough to become the weakest position during tensile test.

scholarly journals Thermodynamic Stabilities of U(VI) Minerals: Estimated and Observed Relationships

1996 ◽  
Vol 465 ◽  
Author(s):  
Robert J. Finch
Keyword(s):  
Gibbs Energy ◽  
Reaction Pathways ◽  
Free Energies ◽  
Fine Grained ◽  
Surface Energies ◽  
Stability Diagrams ◽  
Activity Diagrams ◽  
Mineral Stability ◽  
Mineral Compositions

ABSTRACTGibbs free energies of formation (ΔG°ƒ) for several structurally related U(VI) minerals are estimated by summing the Gibbs energy contributions from component oxides. The estimated ΔG°f values are used to construct activity-activity (stability) diagrams, and the predicted stability fields are compared with observed mineral occurrences and reaction pathways. With some exceptions, natural occurrences agree well with the mineral stability fields estimated for the systems Sio2-Cao-Uo3-UOH2O and Co2-caO-UO3-H2O providing confidence in the estimated thermodynamic values. Activity-activity diagrams are sensitive to small differences in ΔG°f values, and mineral compositions must be known accurately, including structurally bound H2O. The estimated ΔG°f values are not considered reliable for a few minerals for two major reasons: (1) the structures of the minerals in question are not closely similar to those used to estimate the ΔG°f* values of the component oxides, and/or (2) the minerals in question are exceptionally fine grained, leading to large surface energies that increase the effective mineral solubilities.

Geographical and solar activity variations in the electron temperature of the upper F -region

1965 ◽  
Vol 286 (1407) ◽  
pp. 537-558 ◽  
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Geomagnetic Latitude ◽  
Minor Effect ◽  
Night Time ◽  
Temperature Variations ◽  
Geographical Variations ◽  
Magnetic Shell ◽  
Time Changes ◽  
A Minor

Electron temperature observations obtained in April-July 1962 on the Ariel I satellite have been further analysed by a statistical method. The general increase of electron temperature with latitude (amounting to about 500 degK) and with altitude between 400 and 1200 km, ( ca . 600 degK) previously reported, are confirmed. In addition, the dawn maximum of electron temperature found by other workers, which at the period of these observations is only a minor effect at 40° geomagnetic latitude, is found to become more pronounced near the magnetic equator. The geographical variations of electron temperature are shown to divide into distinct patterns characteristic of noon, dawn and midnight. The dawn pattern consists essentially of a longitude variation in the amplitude of the dawn maximum. All three patterns are closely associated with the geographical variations of electron density, and by examining the detailed correlation of temperature and density it is shown that the temperature variations result from changes in the collisional cooling rate of the electrons. This provides confirmation of the explanation of the dawn maximum suggested by Dalgarno, McElroy & Moffat (1963). Temperature variations due to changes in the far u.v. emission of the sun are considered. By day it is found that the electron temperature increases with 2800 Mc/s solar emission at a rate of (4.6 ± 2.3) degK per flux unit of 10 -22 Wcm -2 s -1 (c/s) -1 , while at night it decreases at a rate of 2.3 ± 2.7 degK/flux unit. Temperature variations in magnetic storms are compared with density enhancements described by Willmore & Henderson (1965). Electron density increases in the storm are always accompanied by a temperature reduction of about 180 degK, the storm-time changes showing a distinct magnetic shell structure. An instance of a temperature increase near the Brazilian geomagnetic anomaly is also given. Finally it is shown that these results lend support to the suggestion of a departure from thermal equilibrium in the night-time ionosphere.

scholarly journals Visual and Haptic Representations of Material Properties

2013 ◽  
Vol 26 (5) ◽  
pp. 429-455 ◽  
Author(s):  
Elisabeth Baumgartner ◽  
Christiane B. Wiebel ◽  
Karl R. Gegenfurtner
Keyword(s):  
Principal Components ◽  
Material Properties ◽  
Perceptual Space ◽  
Visual Condition ◽  
Material Recognition ◽  
Haptic Modality ◽  
Fine Grained ◽  
Haptic Exploration ◽  
Material Perception

Research on material perception has received an increasing amount of attention recently. Clearly, both the visual and the haptic sense play important roles in the perception of materials, yet it is still unclear how both senses compare in material perception tasks. Here, we set out to investigate the degree of correspondence between the visual and the haptic representations of different materials. We asked participants to both categorize and rate 84 different materials for several material properties. In the haptic case, participants were blindfolded and asked to assess the materials based on haptic exploration. In the visual condition, participants assessed the stimuli based on their visual impressions only. While categorization performance was less consistent in the haptic condition than in the visual one, ratings correlated highly between the visual and the haptic modality. PCA revealed that all material samples were similarly organized within the perceptual space in both modalities. Moreover, in both senses the first two principal components were dominated by hardness and roughness. These are two material features that are fundamental for the haptic sense. We conclude that although the haptic sense seems to be crucial for material perception, the information it can gather alone might not be quite fine-grained and rich enough for perfect material recognition.

An igneous-textured clast in the Peace River meteorite: insights into accretion and metamorphism of asteroids in the early solar system

2013 ◽  
Vol 50 (1) ◽  
pp. 14-25 ◽  
Author(s):  
Christopher D.K. Herd ◽  
Jon M. Friedrich ◽  
Richard C. Greenwood ◽  
Ian A. Franchi
Keyword(s):  
Solar System ◽  
Isotope Composition ◽  
Parent Body ◽  
Early Solar System ◽  
Element Abundances ◽  
Fine Grained ◽  
Peace River ◽  
Petrology And Geochemistry ◽  
Mineral Compositions ◽  
The Impact

The mineralogy, petrology, and geochemistry of an igneous-textured clast in the Peace River L6 chondrite meteorite was examined to determine the roles of nebular processes, accretion, and parent-body metamorphism in its origin. The centimetre-scale clast is grey and fine grained and is in sharp contact with the host chondrite. Two sub-millimetre veins cut across both the clast and host, indicating that the clast formed prior to the impact (shock) event(s) that produced the numerous veins present in the Peace River meteorite. The clast and host are indistinguishable in terms of mineral compositions. In contrast, there are differences in modal mineralogy, texture, as well as trace element and oxygen isotope composition between the clast and host. These differences strongly suggest that the clast was formed by impact melting of LL-group chondritic material involving loss of Fe–FeS and phosphate components, followed by relatively rapid cooling and incorporation into the Peace River host meteorite. Subsequent metamorphism on the Peace River parent body caused recrystallization of the clast and homogenization of mineral compositions and thermally labile element abundances between the clast and host. Shock metamorphism, including formation of shock melt veins, occurred post-metamorphism, during fragmentation of the L chondrite parent body. The results suggest that the formation of the Peace River parent asteroid included the incorporation of material from other asteroids and that the pre-metamorphic protolith was a breccia. Accordingly, we propose that the Peace River meteorite be reclassified as a polymict breccia.

Effect of Microstructure of Mo-Cu Alloy on the Thermal Expansion Coefficient

2013 ◽  
Vol 873 ◽  
pp. 67-71 ◽  
Author(s):  
Zeng Feng Li ◽  
Hai Yan Liu ◽  
Ai Jun Li ◽  
Han Liang Zhang ◽  
Yuan Ping Huang ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Mechanical Alloying ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
High Energy ◽  
Fine Grained ◽  
Cu Alloy ◽  
Sealing Material ◽  
Lower Temperature ◽  
A Minor

Mo-Cu alloy with high density can be fabricated at lower sintering temperature by high-energy ball-milling mechanical-alloying method and adding activation element. The rule of change of microstructure and its effect on the thermal expansion coefficient are studied. It is found that the holes in the Mo-Cu alloy sintered at lower temperature disappear, and Mo and Cu distribute uniformly. The Mo particles are fine-grained, and distribute uniformly in the Cu particles using the mechanical-alloying method. The change of thermal expansion coefficient with temperature is in accordance with the effect of adding activation element. There is a minor inflexion in the thermal expansion coefficient curve at 500°C. The change of thermal expansion coefficient with temperature is the same as 95% Al2O3 sealing material. Thus, the thermal property between Mo-Cu alloy and 95% Al2O3 match well.

scholarly journals Structural evolution of Variegated Glacier, Alaska, U.S.A., since 1948

1996 ◽  
Vol 42 (141) ◽  
pp. 261-270 ◽  
Author(s):  
Wendy Lawson
Keyword(s):  
Structural Evolution ◽  
Aerial Photographs ◽  
Middle Zone ◽  
Normal Flow ◽  
Lower Zone ◽  
Longitudinal Zonation ◽  
Velocity Gradients ◽  
Flow Processes ◽  
Zone Ii ◽  
Glacier Velocity

AbstractАn excellent photographic database, comprising 12 sets of vertical aerial photographs taken between 1948 and 1993, has enabled the structural glaciology of surge-type Variegated Glacier, Alaska, U.S.A., tо be analyzed for a period that spans two surge cycles and includes the effects of three surges. The glacier-wide patterns of crevasse development at the end of each of these surges, which occurred in 1947–48, 1964–65 and 1982–83, were remarkably similar, despite differences in surge intensities and extents. At the end of each surge a three-fold longitudinal zonation of crevasse orientation characterised that part of the glacier that had been affected by surge activity. This zonation comprises: (i) transverse crevasses in a narrow upper zone, (ii) superimposed longitudinal and transverse crevasses in an extensive middle zone, and (iii) longitudinal crevasses in a narrow lower zone. The main difference between patterns produced by successive surges was small variations in the extent оf the three zones. During quiescence, the most intense crevasse development occurs in the upper glacier in the latter part of quiescence, and is a function of increasingly steep down-glacier velocity gradients developing in the buildup to the impending surge. Some crevassing also develops in the central part of the glacier in mid-quiescence that is not related to the surge nature of the glacier, but to normal flow processes over bedrock. There is no structural evidence to indicate that any of the tributaries of Variegated Glacier surge. This observation suggests that the bulb-like loops in the medial moraines at Variegated Glacier form during quiescence as a result of the steady flow of the tributaries into the stagnant trunk glacier, rather than as a result of tributary surges.

Vulnerability Assessment of Farmer’s Livelihood to Flood in An Giang Province

2019 ◽  
pp. 251660261986062
Author(s):  
P. X. Phu ◽  
N. N. De
Keyword(s):  
Climate Change ◽  
Adaptive Capacity ◽  
Global Environmental Change ◽  
Vulnerability Index ◽  
Livelihood Strategies ◽  
Middle Zone ◽  
Lower Zone ◽  
Knowledge And Skills ◽  
Global Environmental ◽  
Local Farmers

This study, conducted in An Giang Province of Vietnam, assesses the vulnerability and adaptability of local farmers to the flood in different conditions. Livelihood Vulnerability Index (LVI) proposed by Hahn, Riederer, and Foster (2009, Global Environmental Change, 19(1), 74–88) was applied for livelihood vulnerability analysis of different flooding zones (upper, middle and lower zones) in low flooding condition. Research results showed that LVI of different flooding zones are decreasingly dependent on major components of social networks, knowledge and skills, natural resources, finance and incomes, livelihood strategies, and natural disaster and climate variability. In which, LVI of Phu Huu commune in An Phu district which locates in the upper zone is 0.397 higher than LVI of two communes located in the lower parts of the river: Vinh An commune, Chau Thanh district (middle zone; LVI: 0.299) and Vinh Phuoc commune, Tri Ton district (lower zone; LVI: 0.357). Adaptive capacity of Phu Huu commune (0.415) is also higher than Vinh An (0.304) and Vinh Phuoc (0.355) communes. It reflects the direct correlation between LVI and adaptive capacity. The research recommends some solutions to reduce the vulnerability on livelihoods due to floods in the context of climate change.

scholarly journals Personality Research and Assessment in the Era of Machine Learning

2020 ◽  
Vol 34 (5) ◽  
pp. 613-631 ◽  
Author(s):  
Clemens Stachl ◽  
Florian Pargent ◽  
Sven Hilbert ◽  
Gabriella M. Harari ◽  
Ramona Schoedel ◽  
...  
Keyword(s):  
Machine Learning ◽  
Personality Assessment ◽  
Latent Variables ◽  
Learning Models ◽  
Personality Psychology ◽  
Fine Grained ◽  
Personality Research ◽  
Key Issues ◽  
Complex Relationships ◽  
Machine Learning Models

The increasing availability of high–dimensional, fine–grained data about human behaviour, gathered from mobile sensing studies and in the form of digital footprints, is poised to drastically alter the way personality psychologists perform research and undertake personality assessment. These new kinds and quantities of data raise important questions about how to analyse the data and interpret the results appropriately. Machine learning models are well suited to these kinds of data, allowing researchers to model highly complex relationships and to evaluate the generalizability and robustness of their results using resampling methods. The correct usage of machine learning models requires specialized methodological training that considers issues specific to this type of modelling. Here, we first provide a brief overview of past studies using machine learning in personality psychology. Second, we illustrate the main challenges that researchers face when building, interpreting, and validating machine learning models. Third, we discuss the evaluation of personality scales, derived using machine learning methods. Fourth, we highlight some key issues that arise from the use of latent variables in the modelling process. We conclude with an outlook on the future role of machine learning models in personality research and assessment.

The Serra Branca amazonite pegmatite of the Vieirópolis pegmatite field, Paraíba, Brazil: A new and unusual megacrystic amazonite deposit

2020 ◽  
Author(s):  
Glenda Lira Santos ◽  
Igor Manoel Belo De Albuquerque E Souza ◽  
Sandra De Brito Barreto ◽  
José Ferreira De Araújo Neto ◽  
Axel Müller
Keyword(s):  
Major Elements ◽  
Open Pit ◽  
Fine Grained ◽  
Ornamental Stone ◽  
Pegmatite Body ◽  
Borborema Province ◽  
Trace Element Contents ◽  
Complex Relationships ◽  
Low K

Abstract The recently discovered Serra Branca amazonite pegmatite in the state of Paraíba, Brazil, is an evolved niobium-yttrium-fluorine (NYF) granitic pegmatite, which belongs to the Vieirópolis pegmatite field, the first NYF pegmatite field described from the Borborema Province. The pegmatite is an unusually large resource (>300,000 tons) of intensely colored amazonite megacrysts up to 2 m in size, exploited in an open pit since ca. 2010 as an ornamental stone and gemological material. This study provides the first mineralogical and geochemical characterization of the Serra Branca amazonite pegmatite and its mineralogy, which are further compared with the mineralogy and composition of other NYF pegmatites. The Serra Branca pegmatite forms an approximately 800 m-long and up to 3 m-thick flat-dipping sheet that consists of two distinct structural-mineralogical zones with complex relationships: (1) the massive, megacrystic amazonite zone forming commonly in the upper part of the dike and (2) the fine-grained albite zone commonly occurring at the bottom of the dike. The amazonite zone, which comprises ca. 75 vol.% of the pegmatite body, is composed of amazonite and quartz, the major constituents, with accessory biotite, helvine, galena, ilmenite, hematite, columbite-(Mn), phenakite, titanite, magnetite, and rutile. The albite zone consists of saccharoidal albite and quartz and accessory spessartine, ilmenite, zircon, columbite-(Mn), pyrochlore, and fluorite. A younger minor intrusive pegmatitic unit composed of megacrystic euhedral amazonite and quartz and platy albite (cleavelandite) postdates the formation of the amazonite and albite zones. Geochemical analysis of the bulk pegmatite, amazonite zone, and albite zone shows that the bulk pegmatite and the amazonite zone have similar compositions, with high trace-element contents of Ba, Be, Rb, Sr, and Pb, whereas the albite zone is enriched in Zn, Nb, Zr, Ga, and Hf. The amazonite and albite zones display some similarities in terms of major elements, the presence of HFSE minerals, and the distribution of incompatible and REE, which indicates that the two zones originated from the same melt. The amazonite crystals are enriched in Rb, Pb, Sr, Cs, Ba, Tl, Fe, and Ga, characterizing the Serra Branca pegmatite as an evolved NYF pegmatite. This conclusion is confirmed by the low K/Rb ratio of biotite of ∼5.7. Higher Li and Ga and lower Sr and Ba in the amazonite of the minor unit suggests that this melt was even more highly fractionated than the melt of the first emplacement stage.

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