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Paleostress Inversion
Paleostress inversion refers to the determination of paleostress history from evidence found in rocks, based on the principle that past paleostress, tectonic stress should have left traces in the rocks. Such relationships have been discovered from field studies for years: qualitative and quantitative analyses of deformation structures are useful for understanding the distribution and transformation of paleostress fields controlled by sequential tectonic events. Deformation ranges from microscopic to regional scale, and from fracture, brittle to fracture, ductile behaviour, depending on the rheology of the rock, orientation and magnitude of the stress, etc. Therefore, detailed observations in outcrops, as well as in thin sections, are important in reconstructing the paleostress trajectories. Inversions require assumptions in order to simplify the complex geological processes. The stress field is assumed to be spatially uniform for a faulted Rock mechanics, rock mass and temporally s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleostress
Paleostress is a term used in geology (specifically in the fields of structural geology and tectonics) to indicate mechanical stress that has affected rock formations in the geological past. In practice, a paleostress tensor may be quantified based on the measurement of certain geological structures (e.g. Fault (geology), faults), whose specific geometries and spatial organization are theoretically linked to the parameters of the tensor (see paleostress inversion). The latter are quantified through inversion of the structures measured in the field (or potentially on rock samples in the lab). Paleostress is a subset of mechanical stress within geology. Variations in stress fields within the Earth's crust can result in a variety of mechanical responses: *Microscopic: :*Crystal Deformation (engineering), deformation, including crystal twinning, twinning, :*Pressure Solution (chemistry), solution :*Microfractures, :*Aligned fluid inclusions. *Macroscopic: :*Fold (geology), Folding :* ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
P And T Dihedra
P, or p, is the sixteenth letter of the Latin alphabet, used in the modern English alphabet, the alphabets of other western European languages and others worldwide. Its name in English is ''pee'' (pronounced ), plural ''pees''. History The Semitic Pê (mouth), as well as the Greek Π or π ( Pi), and the Etruscan and Latin letters that developed from the former alphabet all symbolized , a voiceless bilabial plosive. Use in writing systems English In English orthography, represents the sound . A common digraph in English is , which represents the sound , and can be used to transliterate ''phi'' in loanwords from Greek. In German, the digraph is common, representing a labial affricate . Most English words beginning with are of foreign origin, primarily French, Latin and Greek; these languages preserve the Proto-Indo-European initial *p. Native English cognates of such words often start with , since English is a Germanic language and thus has undergone Grimm's l ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grain Boundary
In materials science, a grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are two-dimensional defects in the crystal structure, and tend to decrease the electrical and thermal conductivity of the material. Most grain boundaries are preferred sites for the onset of corrosion and for the precipitation of new phases from the solid. They are also important to many of the mechanisms of creep. On the other hand, grain boundaries disrupt the motion of dislocations through a material, so reducing crystallite size is a common way to improve mechanical strength, as described by the Hall–Petch relationship. High and low angle boundaries It is convenient to categorize grain boundaries according to the extent of misorientation between the two grains. ''Low-angle grain boundaries'' (''LAGB'') or ''subgrain boundaries'' are those with a misorientation less than about 15 degrees. Generally speaking they are composed of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dislocation
In materials science, a dislocation or Taylor's dislocation is a linear crystallographic defect or irregularity within a crystal structure that contains an abrupt change in the arrangement of atoms. The movement of dislocations allow atoms to slide over each other at low stress levels and is known as ''glide'' or Slip (materials science), slip. The crystalline order is restored on either side of a ''glide dislocation'' but the atoms on one side have moved by one position. The crystalline order is not fully restored with a ''partial dislocation''. A dislocation defines the boundary between ''slipped'' and ''unslipped'' regions of material and as a result, must either form a complete loop, intersect other dislocations or defects, or extend to the edges of the crystal. A dislocation can be characterised by the distance and direction of movement it causes to atoms which is defined by the Burgers vector. Plasticity (physics), Plastic deformation of a material occurs by the creation and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
BLG Sub '', a genealogical publication
{{disambiguation ...
BLG may refer to: * Former ISO 639-3 code for Balau, a dialect of the Iban language * Barlow Lyde & Gilbert, a British law firm * Belaga Airport, Sarawak, Malaysia * Beluga Airport, Alaska * β-Lactoglobulin * Bilibili Gaming, a Chinese esports franchise * BLG Logistics, a German seaport and logistics company in Bremen * Borden Ladner Gervais, a Canadian law firm * ''Burke's Landed Gentry ''Burke's Landed Gentry'' (originally titled ''Burke's Commoners'') is a reference work listing families in Great Britain and Ireland who have owned rural estates of some size. The work has been in existence from the first half of the 19th cen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grain Growth
In materials science, grain growth is the increase in size of grains (crystallites) in a material at high temperature. This occurs when recovery and recrystallisation are complete and further reduction in the internal energy can only be achieved by reducing the total area of grain boundary. The term is commonly used in metallurgy but is also used in reference to ceramics and minerals. The behaviors of grain growth is analogous to the coarsening behaviors of grains, which implied that both of grain growth and coarsening may be dominated by the same physical mechanism. Importance of grain growth The practical performances of polycrystalline materials are strongly affected by the formed microstructure inside, which is mostly dominated by grain growth behaviors. For example, most materials exhibit the Hall–Petch effect at room-temperature and so display a higher yield stress when the grain size is reduced (assuming abnormal grain growth has not taken place). At high temperatur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Quartz Recrystallization
Quartz is the most abundant single mineral in the Earth's crust (although behind the feldspar group when taken collectively), and as such is present in a very large proportion of rocks both as primary crystals and as detrital grains in sedimentary and metamorphic rocks. Dynamic recrystallization is a process of crystal regrowth under conditions of stress and elevated temperature, commonly applied in the fields of metallurgy and materials science. Dynamic quartz recrystallization happens in a relatively predictable way with relation to temperature, and given its abundance quartz recrystallization can be used to easily determine relative temperature profiles, for example in orogenic belts or near intrusions. Mechanisms of recrystallization Previous research has outlined several dislocation creep regimes present in experimental conditions. Two main mechanisms for altering grain boundaries have been defined. The first is the process by which quartz softens as temperature increases, p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Mantle (Earth)
The upper mantle of Earth is a very thick layer of rock inside the planet, which begins just beneath the crust (at about under the oceans and about under the continents) and ends at the top of the lower mantle the . Temperatures range from approximately at the upper boundary with the crust to approximately at the boundary with the lower mantle. Upper mantle material that has come up onto the surface comprises about 55% olivine, 35% pyroxene, and 5 to 10% of calcium oxide and aluminum oxide minerals such as plagioclase, spinel, or garnet, depending upon depth. Seismic structure The density profile through Earth is determined by the velocity of seismic waves. Density increases progressively in each layer, largely due to compression of the rock at increased depths. Abrupt changes in density occur where the material composition changes. The upper mantle begins just beneath the crust and ends at the top of the lower mantle. The upper mantle causes the tectonic plates to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Grain Boundaries
In materials science, a grain boundary is the interface between two grains, or crystallites, in a polycrystalline material. Grain boundaries are two-dimensional crystallographic defect, defects in the crystal structure, and tend to decrease the electrical conductivity, electrical and thermal conductivity of the material. Most grain boundaries are preferred sites for the onset of corrosion and for the precipitation (chemistry), precipitation of new Phase (matter), phases from the solid. They are also important to many of the mechanisms of Creep (deformation), creep. On the other hand, grain boundaries disrupt the motion of dislocations through a material, so reducing crystallite size is a common way to improve mechanical strength, as described by the Hall–Petch relationship. High and low angle boundaries It is convenient to categorize grain boundaries according to the extent of misorientation between the two grains. ''Low-angle grain boundaries'' (''LAGB'') or ''subgrain boun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deformation (mechanics)
In physics and continuum mechanics, deformation is the change in the shape (geometry), shape or size of an object. It has dimension (physics), dimension of length with SI unit of metre (m). It is quantified as the residual displacement (geometry), displacement of particles in a non-rigid body, from an configuration to a configuration, excluding the body's average translation (physics), translation and rotation (its rigid transformation). A ''configuration'' is a set containing the position (geometry), positions of all particles of the body. A deformation can occur because of structural load, external loads, intrinsic activity (e.g. muscle contraction), body forces (such as gravity or electromagnetic forces), or changes in temperature, moisture content, or chemical reactions, etc. In a continuous body, a ''deformation field'' results from a Stress (physics), stress field due to applied forces or because of some changes in the conditions of the body. The relation between stre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Piezometer
Pressure measurement is the measurement of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in unit of measurement, units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure mechanically are called pressure gauges, vacuum gauges or compound gauges (vacuum & pressure). The widely used Bourdon gauge is a mechanical device, which both measures and indicates and is probably the best known type of gauge. A vacuum gauge is used to measure pressures lower than the ambient atmospheric pressure, which is set as the zero point, in negative values (for instance, −1 bar or −760 mmHg equals total vacuum). Most gauges measure pressure relative to atmospheric pressure as the zero point, so this form of reading is simply referred to as "gauge pressure". However, anything greater than total vacuum is technically a form of pressure. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Swiss J Geosci
Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in Berlin, it expanded internationally in the 1960s, and through mergers in the 1990s and a sale to venture capitalists it fused with Wolters Kluwer and eventually became part of Springer Nature in 2015. Springer has major offices in Berlin, Heidelberg, Dordrecht, and New York City. History Julius Springer founded Springer-Verlag in Berlin in 1842 and his son Ferdinand Springer grew it from a small firm of 4 employees into Germany's then second-largest academic publisher with 65 staff in 1872.Chronology ". Springer Science+Business Media. In 1964, Springer expanded its business internationally, op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
