A crustal model of the ultrahigh-pressure Dabie Shan orogenic belt
... shear wave data indicate that Poisson’s ratio increases from 0.24 ⫾ 0.02 in the upper crust to 0.27 ⫾ 0.03 in the lower crust. This result is consistent with a dominantly felsic upper crustal composition and a mafic lower crustal composition within the amphibolite or granulite metamorphic facies. Ou ...
... shear wave data indicate that Poisson’s ratio increases from 0.24 ⫾ 0.02 in the upper crust to 0.27 ⫾ 0.03 in the lower crust. This result is consistent with a dominantly felsic upper crustal composition and a mafic lower crustal composition within the amphibolite or granulite metamorphic facies. Ou ...
BASIN TYPES ACCORDING TO TECTONIC by Prof. Dr. Abbas
... • The basins are infilled by prisms of terrigenous elastics which were deposited in a range of environments. On the landward sides of the embayments alluvial deposits predominate. These ...
... • The basins are infilled by prisms of terrigenous elastics which were deposited in a range of environments. On the landward sides of the embayments alluvial deposits predominate. These ...
Postglacial rebound at the northern Cascadia subduction zone
... less than 10 Pa s (Sigmundsson, 1991). This is consistent with crustal tilting related to historical thinning of the Vatnajokull ice cap in Iceland, which gives a viscosity of 10 to 5;10 Pa s (Sigmundsson and Einarsson, 1992). Relative sea level changes due to hydro-isostasy in the backarc env ...
... less than 10 Pa s (Sigmundsson, 1991). This is consistent with crustal tilting related to historical thinning of the Vatnajokull ice cap in Iceland, which gives a viscosity of 10 to 5;10 Pa s (Sigmundsson and Einarsson, 1992). Relative sea level changes due to hydro-isostasy in the backarc env ...
Topic The IASPEI standard nomenclature of seismic
... This increased flexibility of the parameter-reporting format requires improved standardization, which limits an uncontrolled growth of incompatible and ambiguous parameter data. Therefore, the WG agreed on certain rules. They are outlined below prior to the listing of standardized phase names. In or ...
... This increased flexibility of the parameter-reporting format requires improved standardization, which limits an uncontrolled growth of incompatible and ambiguous parameter data. Therefore, the WG agreed on certain rules. They are outlined below prior to the listing of standardized phase names. In or ...
Large-Scale Thermo-chemical Structure of the Deep Mantle
... no notable large-scale structure is observed, and the RMS seismic velocity variation is small, 0.5 % or less. Below the surface, anomalies of shear-wave velocity are well correlated with surface tectonics down to depths of about 200–300 km (Schaeffer and Lebedev, this volume). The ocean–continent di ...
... no notable large-scale structure is observed, and the RMS seismic velocity variation is small, 0.5 % or less. Below the surface, anomalies of shear-wave velocity are well correlated with surface tectonics down to depths of about 200–300 km (Schaeffer and Lebedev, this volume). The ocean–continent di ...
Metallogenesis of the world`s ocean against the background
... processes controlled by groups of factors differing regionally and locally. The key differentiating factors include sources, and more precisely mutual relations between the kind and amount of allogenic and authigenic components delivered to different oceans, distance away from endogenic sources, dep ...
... processes controlled by groups of factors differing regionally and locally. The key differentiating factors include sources, and more precisely mutual relations between the kind and amount of allogenic and authigenic components delivered to different oceans, distance away from endogenic sources, dep ...
Orogens and slabs vs. their direction of subduction
... few centimeters per year remains. This is mainly due to the high speed of the Pacific plate toward the ‘west’ which is not entirely compensated by the other plates which are moving in the opposite or different directions. Ricard et al. Ž1991. show that lateral heterogeneities in the asthenospheric v ...
... few centimeters per year remains. This is mainly due to the high speed of the Pacific plate toward the ‘west’ which is not entirely compensated by the other plates which are moving in the opposite or different directions. Ricard et al. Ž1991. show that lateral heterogeneities in the asthenospheric v ...
The asthenosphere low-velocity layer Over 100 years ago, Airy and
... part of the mantle is probably far from being casual and is connected with a velocity decrease of seismic waves " (Gorslikov, 1958, p. 28). " The most probable reason for this phenomenon is a transition from a crystalline state into an amorplious condition " (Gorshkov, 1958, p. 109). These results g ...
... part of the mantle is probably far from being casual and is connected with a velocity decrease of seismic waves " (Gorslikov, 1958, p. 28). " The most probable reason for this phenomenon is a transition from a crystalline state into an amorplious condition " (Gorshkov, 1958, p. 109). These results g ...
Multiple sulfur isotope composition of oxidized Samoan melts and
... which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+ ) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yiel ...
... which defines the enriched-mantle-2 (EM2) endmember. Bulk S abundances vary between 835 and 2279 ppm. About 17 ± 11% of sulfur is oxidized (S6+ ) but displays no consistent trend with bulk S abundance or any other geochemical tracer. The S isotope composition of both dissolved sulfide and sulfate yiel ...
Kinematic reconstruction of the Caribbean
... circuit of plate motions using a mantle reference frame, they become key input for the assessment of how lithospheric evolution is coupled to underlying mantle processes and mantle structure (Spakman and Hall, 2010). ...
... circuit of plate motions using a mantle reference frame, they become key input for the assessment of how lithospheric evolution is coupled to underlying mantle processes and mantle structure (Spakman and Hall, 2010). ...
Submarine Silicic Volcanism Niyati G. Kalangutkar* and
... parent magma and by crustal anatexis. Several evidences show the origin of some rhyolitic and andesitic magma to be related due to similar tectonic settings. Fractional crystallisation: This process produces a series of residual liquids of variable compositions as compared to their parental magmas a ...
... parent magma and by crustal anatexis. Several evidences show the origin of some rhyolitic and andesitic magma to be related due to similar tectonic settings. Fractional crystallisation: This process produces a series of residual liquids of variable compositions as compared to their parental magmas a ...
Propagating rift model for the V‐shaped ridges south of Iceland
... Fracture Zone; V, Vestfirdir; S, Snæfellsnes; R, Reykjanes Peninsula. ...
... Fracture Zone; V, Vestfirdir; S, Snæfellsnes; R, Reykjanes Peninsula. ...
Reconstructing the Alps–Carpathians–Dinarides as a key to
... been galvanized in the past decade by teleseismic tomographic images of two positive compressive-wave velocity (+Vp) slab anomalies with contrasting orientations beneath the Alps (Fig. 4a–c): one beneath the Central and Western Alps that dips to the southeast to a depth of about 200 km and is consis ...
... been galvanized in the past decade by teleseismic tomographic images of two positive compressive-wave velocity (+Vp) slab anomalies with contrasting orientations beneath the Alps (Fig. 4a–c): one beneath the Central and Western Alps that dips to the southeast to a depth of about 200 km and is consis ...
Alfred Wegener`s Hypothesis on Continental Drift and Its Discussion
... the Berlin Geographical Society and published a paper in their journal in 1921. During the international dispute in the 1920s, with the majority of geo-scientists strongly declining the possibility of horizontal continental drifts, the two meteorologists Wegener and Köppen came up with their most im ...
... the Berlin Geographical Society and published a paper in their journal in 1921. During the international dispute in the 1920s, with the majority of geo-scientists strongly declining the possibility of horizontal continental drifts, the two meteorologists Wegener and Köppen came up with their most im ...
ARTICLE IN PRESS - Do plumes exist?
... The kinematics of subduction zones shows a variety of settings that can provide clues for dynamic understandings. Two reference frames are used here to describe the simple 2D kinematics of subduction zones. In the first, the upper plate is assumed fixed, whereas in the second frame upper and lower p ...
... The kinematics of subduction zones shows a variety of settings that can provide clues for dynamic understandings. Two reference frames are used here to describe the simple 2D kinematics of subduction zones. In the first, the upper plate is assumed fixed, whereas in the second frame upper and lower p ...
Contribution of gravitational potential energy differences to the
... show that for a thin sheet calculation in which the vertical stress varies beneath topography along the base of the depth of integration, there is only one correct level of reference. In particular, we show that for such cases, the shallow density anomalies have a more dominant effect on the depth i ...
... show that for a thin sheet calculation in which the vertical stress varies beneath topography along the base of the depth of integration, there is only one correct level of reference. In particular, we show that for such cases, the shallow density anomalies have a more dominant effect on the depth i ...
Moreno, MS
... interseismic phase [e.g., McCaffrey and Goldfinger, 1995; McCaffrey et al., 2007], or both. The effect of motion on these upper plate faults is expressed as short wavelength, but high-amplitude deformation localized in the vicinity of the structure. These faults may be crustal-scale features rooted ...
... interseismic phase [e.g., McCaffrey and Goldfinger, 1995; McCaffrey et al., 2007], or both. The effect of motion on these upper plate faults is expressed as short wavelength, but high-amplitude deformation localized in the vicinity of the structure. These faults may be crustal-scale features rooted ...
2.3. New Zealand – Primary Site 1. Background and Motivation
... motion of AUS or MACQ with respect to fixed PAC from MORVEL present day plate model. ...
... motion of AUS or MACQ with respect to fixed PAC from MORVEL present day plate model. ...
42. The New England Seamounts
... is up to 12 m.y. older than Nashville. This is strongly dependent on the 91.3 ±3 m.y. radiometric age of the Vogel breccia, and a very tentative Coniacian-Santonian age for the overlying volcanogenic sediment. As noted earlier, a 4 cm/year migration rate leads to an ~ 10 m.y. age difference between ...
... is up to 12 m.y. older than Nashville. This is strongly dependent on the 91.3 ±3 m.y. radiometric age of the Vogel breccia, and a very tentative Coniacian-Santonian age for the overlying volcanogenic sediment. As noted earlier, a 4 cm/year migration rate leads to an ~ 10 m.y. age difference between ...
Active thrusting in the inner forearc of an erosive convergent margin
... trench migration at the front of the wedge. Active thrusting in the inner forearc along these margins could allow for loading and underthrusting of the outer forearc and could account for at least some of the arcward trench migration and subsidence of the upper slope. The Fila Costeña thrust belt i ...
... trench migration at the front of the wedge. Active thrusting in the inner forearc along these margins could allow for loading and underthrusting of the outer forearc and could account for at least some of the arcward trench migration and subsidence of the upper slope. The Fila Costeña thrust belt i ...
Faults and Earthquakes - Indiana Geological Survey
... plates move at a rate of about a ½ inch to 4 inches per year, displacing continental land masses and ocean floor alike. The forces that move the plates create stresses within the Earth’s crust, and can cause the crust to suddenly fracture. The area of contact between the two fractured crustal masses ...
... plates move at a rate of about a ½ inch to 4 inches per year, displacing continental land masses and ocean floor alike. The forces that move the plates create stresses within the Earth’s crust, and can cause the crust to suddenly fracture. The area of contact between the two fractured crustal masses ...
Hotspots, mantle plumes and core heat loss
... plumes, by far the more numerous, seldom make their way to the top boundary. The fact that the average depth cold plume reach is not exactly the maximum depth comes from the fact that there is always one on its way to the bottom boundary. Many hot plumes start because there is a local minimum in the ...
... plumes, by far the more numerous, seldom make their way to the top boundary. The fact that the average depth cold plume reach is not exactly the maximum depth comes from the fact that there is always one on its way to the bottom boundary. Many hot plumes start because there is a local minimum in the ...
evidence from Th, Sr and Pb isotope data for Tonga
... estimates of between 20 ka and 6 Ma for the residence time of U, Th and Be in the mantle wedge. These various estimates may reflect real differences in transport times between arcs, or variable transport rates for different elements. Recent studies have shown that although crustallevel contamination ...
... estimates of between 20 ka and 6 Ma for the residence time of U, Th and Be in the mantle wedge. These various estimates may reflect real differences in transport times between arcs, or variable transport rates for different elements. Recent studies have shown that although crustallevel contamination ...
Plate tectonics
Plate tectonics (from the Late Latin tectonicus, from the Greek: τεκτονικός ""pertaining to building"") is a scientific theory that describes the large-scale motion of Earth's lithosphere. This theoretical model builds on the concept of continental drift which was developed during the first few decades of the 20th century. The geoscientific community accepted the theory after the concepts of seafloor spreading were later developed in the late 1950s and early 1960s.The lithosphere, which is the rigid outermost shell of a planet (on Earth, the crust and upper mantle), is broken up into tectonic plates. On Earth, there are seven or eight major plates (depending on how they are defined) and many minor plates. Where plates meet, their relative motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates typically varies from zero to 100 mm annually.Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some supporters) propose gradual shrinking (contraction) or gradual expansion of the globe.Tectonic plates are able to move because the Earth's lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative importance of each of these factors and their relationship to each other is unclear, and still the subject of much debate.