The Agulhas – Karoo Geoscience Transect: from a sheared margin
... accumulate or accrete when continental margins are active. Today, oceanic plateaux, which can be extinct island arcs, extinct spreading ridges, seamounts, or disrupted fragments of continental crust, are passive features that are embedded within the oceanic lithosphere. When large enough, they resis ...
... accumulate or accrete when continental margins are active. Today, oceanic plateaux, which can be extinct island arcs, extinct spreading ridges, seamounts, or disrupted fragments of continental crust, are passive features that are embedded within the oceanic lithosphere. When large enough, they resis ...
Convective destabilization of a thickened continental lithosphere
... has been thickened over the whole box length. Bold numbers mark simulations where the main destabilization mechanism is due to £ow on the root sides. ...
... has been thickened over the whole box length. Bold numbers mark simulations where the main destabilization mechanism is due to £ow on the root sides. ...
Metamorphic chemical geodynamics of subduction zones
... deeply subducted, then exhumed relatively rapidly during later continent–continent collisions (e.g., Western Alps; Ernst, 2006). Their mineral assemblages, textures, and geochemistry preserve histories of their seafloor origins, prograde recrystallization, and later exhumation, and if studied with c ...
... deeply subducted, then exhumed relatively rapidly during later continent–continent collisions (e.g., Western Alps; Ernst, 2006). Their mineral assemblages, textures, and geochemistry preserve histories of their seafloor origins, prograde recrystallization, and later exhumation, and if studied with c ...
Thermal structure and intermediate-depth seismicity in the Tohoku
... n = 3.5 and R is the gas constant. We use a maximum viscosity cut-off of 1025 Pa s. For the continental crust we assume density 2700 kg m−3 , conductivity 2.5 W mK−1 , and a twolayer heat production of 1.31 µW m−3 above 15 km depth and 0.27 µW m−3 below this depth. For the rest of the model (includi ...
... n = 3.5 and R is the gas constant. We use a maximum viscosity cut-off of 1025 Pa s. For the continental crust we assume density 2700 kg m−3 , conductivity 2.5 W mK−1 , and a twolayer heat production of 1.31 µW m−3 above 15 km depth and 0.27 µW m−3 below this depth. For the rest of the model (includi ...
Bebout Metamorphic chemical geodynamics of subduction zones
... deeply subducted, then exhumed relatively rapidly during later continent–continent collisions (e.g., Western Alps; Ernst, 2006). Their mineral assemblages, textures, and geochemistry preserve histories of their seafloor origins, prograde recrystallization, and later exhumation, and if studied with c ...
... deeply subducted, then exhumed relatively rapidly during later continent–continent collisions (e.g., Western Alps; Ernst, 2006). Their mineral assemblages, textures, and geochemistry preserve histories of their seafloor origins, prograde recrystallization, and later exhumation, and if studied with c ...
Harris, 2007
... Although our understanding of the creation and subduction of oceanic lithosphere has advanced rapidly over the past few decades, the processes that control mountain building within the continents remain highly contentious. Recent developments in quantitative modelling of lithospheric deformation, co ...
... Although our understanding of the creation and subduction of oceanic lithosphere has advanced rapidly over the past few decades, the processes that control mountain building within the continents remain highly contentious. Recent developments in quantitative modelling of lithospheric deformation, co ...
California terranes
... (Şengör and Dewey, 1990, and references therein; Hansen and Dusel-Bacon, 1998; Moores and Day, 1984). 3. Many tectonic models for the western United States have considered only east-dipping subduction zones, and the role of terranes in structural development of an orogen has seldom been considered ...
... (Şengör and Dewey, 1990, and references therein; Hansen and Dusel-Bacon, 1998; Moores and Day, 1984). 3. Many tectonic models for the western United States have considered only east-dipping subduction zones, and the role of terranes in structural development of an orogen has seldom been considered ...
Science Article PDF - Geological Society of America
... (summarized in Barker and Dalziel [1983] and Lawver et al. [1995]), because the more we learn about its structure and morphology, the more difficult it is to postulate a simple model to explain its tectonic evolution. Subduction has occurred along the southern South America–Antarctic Peninsula margi ...
... (summarized in Barker and Dalziel [1983] and Lawver et al. [1995]), because the more we learn about its structure and morphology, the more difficult it is to postulate a simple model to explain its tectonic evolution. Subduction has occurred along the southern South America–Antarctic Peninsula margi ...
Earth History
... • meteorite bombardment ceased, and parts of the rock record begin • to survive. • The volume of continental crust increased dramatically (by the • end of the Archean, ~85% of modern continental area was • present). • This indicates that plate tectonics was in action. ...
... • meteorite bombardment ceased, and parts of the rock record begin • to survive. • The volume of continental crust increased dramatically (by the • end of the Archean, ~85% of modern continental area was • present). • This indicates that plate tectonics was in action. ...
Oceanic lithosphereasthenosphere boundary from surface wave
... The concept of the lithosphere and asthenosphere, and therefore of the lithosphere-asthenosphere boundary (hereafter referred to as the LAB), was first evoked by Barrell [1914] and then extended by Daly [1940]. However, it remains very elusive, as different geophysical fields have proposed different defi ...
... The concept of the lithosphere and asthenosphere, and therefore of the lithosphere-asthenosphere boundary (hereafter referred to as the LAB), was first evoked by Barrell [1914] and then extended by Daly [1940]. However, it remains very elusive, as different geophysical fields have proposed different defi ...
Three-dimensional density model of the upper mantle in
... To investigate the upper mantle density structure, it is necessary to reduce beforehand the impact of the crust, which completely hides the effect of the upper mantle density variations. Therefore, construction of a trustworthy three-dimensional density model of the crust, based on independent data ...
... To investigate the upper mantle density structure, it is necessary to reduce beforehand the impact of the crust, which completely hides the effect of the upper mantle density variations. Therefore, construction of a trustworthy three-dimensional density model of the crust, based on independent data ...
Isostasy and structure of the lower crust and upper mantle in the
... their outcrop areas in the northwest part of the State are shown in Figure 1 of Drummond (1981, this issue). Following Gee (1979b), a 'block' is taken as the exposed part of a stabilised 'craton'. Brief sum• maries of the geology are given by Drummond (1979c, 1981) and comprehensive descriptions can ...
... their outcrop areas in the northwest part of the State are shown in Figure 1 of Drummond (1981, this issue). Following Gee (1979b), a 'block' is taken as the exposed part of a stabilised 'craton'. Brief sum• maries of the geology are given by Drummond (1979c, 1981) and comprehensive descriptions can ...
Oceanic lithosphere-asthenosphere boundary from - HAL
... The concept of the lithosphere and asthenosphere, and therefore of the lithosphere-asthenosphere boundary (hereafter referred to as the LAB), was first evoked by Barrell [1914] and then extended by Daly [1940]. However, it remains very elusive, as different geophysical fields have proposed different defi ...
... The concept of the lithosphere and asthenosphere, and therefore of the lithosphere-asthenosphere boundary (hereafter referred to as the LAB), was first evoked by Barrell [1914] and then extended by Daly [1940]. However, it remains very elusive, as different geophysical fields have proposed different defi ...
mid-ocean ridge tectonics, volcanism
... supply (B and C). In (A), the depth scale applies only to the axial depth profile; numbers denote discontinuities and segments of orders 1–3. Decompression partial melting in upwelling asthenosphere occurs at depths 30–60 km beneath the ridge. As the melt ascends through a more slowly rising solid r ...
... supply (B and C). In (A), the depth scale applies only to the axial depth profile; numbers denote discontinuities and segments of orders 1–3. Decompression partial melting in upwelling asthenosphere occurs at depths 30–60 km beneath the ridge. As the melt ascends through a more slowly rising solid r ...
Variations of phase velocity and gradient values of ULF
... The amplitude, gradient and phase velocity values and probabilities of directions of gradient and phase velocity vectors were constructed for the every frequency band. Apparent resistivities of the Earth’s crust in the every frequency band were calculated using the phase velocity values. It was foun ...
... The amplitude, gradient and phase velocity values and probabilities of directions of gradient and phase velocity vectors were constructed for the every frequency band. Apparent resistivities of the Earth’s crust in the every frequency band were calculated using the phase velocity values. It was foun ...
A relatively reduced Hadean continental crust and - HAL
... estimated to be, on average, ~2 log units (1: Trail et al., 2011), note that given an error of 50 °C in temperature for example (see below), the calculated fO2 relative to the QFM system would be shifted by ~1.0-1.5 log units; however, the calculated fO2 of the modern continental crust, mostly QFM- ...
... estimated to be, on average, ~2 log units (1: Trail et al., 2011), note that given an error of 50 °C in temperature for example (see below), the calculated fO2 relative to the QFM system would be shifted by ~1.0-1.5 log units; however, the calculated fO2 of the modern continental crust, mostly QFM- ...
Structure of the crust and uppermost mantle beneath the western
... [7] In ambient noise tomography (ANT), uncertainties in the dispersion measurements are determined by repeating the measurements over disjoint time intervals [e.g., Bensen et al., 2007]. Uncertainties at different nodes in the dispersion maps, however, are estimated using a new method of tomography ...
... [7] In ambient noise tomography (ANT), uncertainties in the dispersion measurements are determined by repeating the measurements over disjoint time intervals [e.g., Bensen et al., 2007]. Uncertainties at different nodes in the dispersion maps, however, are estimated using a new method of tomography ...
Geo-neutrino Overview - University of Hawaii Physics and Astronomy
... • Correlation matrix used by GNSM (Fogli et al (2006)) could be extended ?? if correlation coefficients among different crustal types are given. ...
... • Correlation matrix used by GNSM (Fogli et al (2006)) could be extended ?? if correlation coefficients among different crustal types are given. ...
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.