Earthquakes and the Interior
... Earthquakes and the Interior Earthquakes are definitely a geologic hazard for people living in earthquake regions, but the seismic waves generated by earthquakes are invaluable for studying the interior of Earth. Earthquake waves indicate several things about Earth’s Interior: 1) Earth appears t ...
... Earthquakes and the Interior Earthquakes are definitely a geologic hazard for people living in earthquake regions, but the seismic waves generated by earthquakes are invaluable for studying the interior of Earth. Earthquake waves indicate several things about Earth’s Interior: 1) Earth appears t ...
Synthesis of Results From the CD-ROM Experiment
... under the Archean (Dueker et al., 2001; Yuan and Dueker, this volume; Levander and Niu, 2004). The most plausible explanation for the north-dipping, high velocity, mantle anomaly is that it is an ancient slab fragment, for example a remnant of the rifted margin of the Wyoming Province (Tyson et al., ...
... under the Archean (Dueker et al., 2001; Yuan and Dueker, this volume; Levander and Niu, 2004). The most plausible explanation for the north-dipping, high velocity, mantle anomaly is that it is an ancient slab fragment, for example a remnant of the rifted margin of the Wyoming Province (Tyson et al., ...
Distributed deformation in the lower crust and upper mantle beneath
... unbroken Moho underlying a seismically anisotropic lower crust beneath the two northernmost faults of the fault system. These observations suggest that distributed deformation, not slip on a narrow vertical fault, accommodates displacement in the lower crust below the 120–480 km of right-lateral sli ...
... unbroken Moho underlying a seismically anisotropic lower crust beneath the two northernmost faults of the fault system. These observations suggest that distributed deformation, not slip on a narrow vertical fault, accommodates displacement in the lower crust below the 120–480 km of right-lateral sli ...
TWS Sample 7 Landforms 5th grade
... Convergent plate boundaries are where two separate plates collide into eachother. One plate is subducted beneath the other. The impact of the two plates colliding create landforms such as mountain ranges and uplift. 2) Explain a transform plate boundary. A transform plate boundary is where the two p ...
... Convergent plate boundaries are where two separate plates collide into eachother. One plate is subducted beneath the other. The impact of the two plates colliding create landforms such as mountain ranges and uplift. 2) Explain a transform plate boundary. A transform plate boundary is where the two p ...
The Earth in cross-section: what`s down there and how we know it
... This is the gradient in density determined by the seismic wave velocities. To obtain density, one must integrate by fixing the density, , and gravity, g, at the top of the layer and calculating both and g as one proceeds downwards. The calculation assumes a simple compression of material that d ...
... This is the gradient in density determined by the seismic wave velocities. To obtain density, one must integrate by fixing the density, , and gravity, g, at the top of the layer and calculating both and g as one proceeds downwards. The calculation assumes a simple compression of material that d ...
A tensile, flexural model for the initiation of subduction
... necessary to balance the component of the plate’s weight directed down the margin slope. We show that this tension can more than offset ridge push. In our model, an important additional tension arises from basal shear tractions resisting the plate’s motion away from the mid-ocean ridge, although the ...
... necessary to balance the component of the plate’s weight directed down the margin slope. We show that this tension can more than offset ridge push. In our model, an important additional tension arises from basal shear tractions resisting the plate’s motion away from the mid-ocean ridge, although the ...
Densities of metapelitic rocks at high to ultrahigh
... densities still below a value of 3.0 g/cm3. However, simplified calculations for specific crustal units (e.g. lower crust) have already demonstrated [7,8] that the densities of such rocks can exceed this value when pressures had increased to 12 kbar and more (T N 500 °C). This density increase is, a ...
... densities still below a value of 3.0 g/cm3. However, simplified calculations for specific crustal units (e.g. lower crust) have already demonstrated [7,8] that the densities of such rocks can exceed this value when pressures had increased to 12 kbar and more (T N 500 °C). This density increase is, a ...
Introduction to the special issue on “Subduction Zones”
... enters a subduction zone, the positive buoyancy of the continental crust will resist subduction, leading to a slow-down, and ultimately to the end of subduction (e.g., McKenzie, 1969). Continental collision is accompanied by severe crustal and lithospheric deformation, mountain building, slab breako ...
... enters a subduction zone, the positive buoyancy of the continental crust will resist subduction, leading to a slow-down, and ultimately to the end of subduction (e.g., McKenzie, 1969). Continental collision is accompanied by severe crustal and lithospheric deformation, mountain building, slab breako ...
An Introduction to Terrane Analysis in the Western North American
... thrusting in Nevada Rift basin in southwestern North America related to opening Gulf of Mexico Blakey and Umhoefer, 2003 ...
... thrusting in Nevada Rift basin in southwestern North America related to opening Gulf of Mexico Blakey and Umhoefer, 2003 ...
Materials Needed for the Lesson - Lake Science Collaborative
... Much of the magma in Earth is produced 100-200 kilometers below the surface. Earth’s heat comes from (1) radioactive decay and (2) residual heat which is gravitational energy left over from Earth’s formation. The hot, moving mantle, consisting of melted rocks and minerals, is responsible for many ge ...
... Much of the magma in Earth is produced 100-200 kilometers below the surface. Earth’s heat comes from (1) radioactive decay and (2) residual heat which is gravitational energy left over from Earth’s formation. The hot, moving mantle, consisting of melted rocks and minerals, is responsible for many ge ...
Volcanoes Erupt - Lake Science Collaborative Teacher Lesson Plans
... Much of the magma in Earth is produced 100-200 kilometers below the surface. Earth’s heat comes from (1) radioactive decay and (2) residual heat which is gravitational energy left over from Earth’s formation. The hot, moving mantle, consisting of melted rocks and minerals, is responsible for many ge ...
... Much of the magma in Earth is produced 100-200 kilometers below the surface. Earth’s heat comes from (1) radioactive decay and (2) residual heat which is gravitational energy left over from Earth’s formation. The hot, moving mantle, consisting of melted rocks and minerals, is responsible for many ge ...
Metamorphic Rocks Summary
... occurs within the thick piles of sediment at the base of the continental slope; regional metamorphism occurs in regions of subduction and continental collision. High pressure and low temperature metamorphism happens within a subducted plate of oceanic lithosphere, and in any sediment carried down by ...
... occurs within the thick piles of sediment at the base of the continental slope; regional metamorphism occurs in regions of subduction and continental collision. High pressure and low temperature metamorphism happens within a subducted plate of oceanic lithosphere, and in any sediment carried down by ...
Puzzling Plates
... Plates converge, which means two plates move toward each other. Usually an oceanic plate converges with a continental plate. Since oceanic plates are more dense than continental plates, ocean plates are subducted or go down into the mantle in an area called the subduction zone. This type of boundary ...
... Plates converge, which means two plates move toward each other. Usually an oceanic plate converges with a continental plate. Since oceanic plates are more dense than continental plates, ocean plates are subducted or go down into the mantle in an area called the subduction zone. This type of boundary ...
Chapter 2.pmd
... several concentric layers with one inside another (Fig. 2.1). The uppermost layer over the earth’s surface is called the crust. It is the thinnest of all the layers. It is about 35 km. on the continental masses and only 5 km. on the ocean floors. The main mineral constituents of the continental mass ...
... several concentric layers with one inside another (Fig. 2.1). The uppermost layer over the earth’s surface is called the crust. It is the thinnest of all the layers. It is about 35 km. on the continental masses and only 5 km. on the ocean floors. The main mineral constituents of the continental mass ...
Subduction - Géosciences Montpellier
... allows nearly all oceanic lithosphere to be recycled into the mantle. By contrast, only the lower portion of the continental lithosphere (the lithospheric mantle) may, under certain conditions, be transported into the deep mantle. Since the continental crust resists subduction at depths beyond about ...
... allows nearly all oceanic lithosphere to be recycled into the mantle. By contrast, only the lower portion of the continental lithosphere (the lithospheric mantle) may, under certain conditions, be transported into the deep mantle. Since the continental crust resists subduction at depths beyond about ...
Map Reading and Earthquake/Volcano Plotting Activity
... in certain areas, the west coasts of North and South America, the border between Europe and Africa and in the islands of the Pacific. Any random earthquakes and volcanoes could be associated with hotspots or faults (cracks) in the crust. ...
... in certain areas, the west coasts of North and South America, the border between Europe and Africa and in the islands of the Pacific. Any random earthquakes and volcanoes could be associated with hotspots or faults (cracks) in the crust. ...
Resolving the fine scale structure of the core
... mantle, is probably the most important internal boundary of the Earth. Strong elastic heterogeneities have been mapped close to the core-mantle boundary (CMB) over the last 20 years. The large variety of heterogeneities found at or near the CMB is not unexpected for this boundary layer that exhibits ...
... mantle, is probably the most important internal boundary of the Earth. Strong elastic heterogeneities have been mapped close to the core-mantle boundary (CMB) over the last 20 years. The large variety of heterogeneities found at or near the CMB is not unexpected for this boundary layer that exhibits ...
A low velocity belt beneath northern and eastern Tibetan Plateau
... 1992]. These observations are consistent with the notion that the crust and the lithosphere in the northern TP are hot and deformable. Three mechanisms have been proposed to explain the source of heat: convective removal [Molnar et al., 1993]; subduction-induced upwelling [Tilman and Ni, 2003], and ...
... 1992]. These observations are consistent with the notion that the crust and the lithosphere in the northern TP are hot and deformable. Three mechanisms have been proposed to explain the source of heat: convective removal [Molnar et al., 1993]; subduction-induced upwelling [Tilman and Ni, 2003], and ...
A tensile, flexural model for the initiation of subduction
... 0.001 per cent of the total volume of Phanerozoic ocean crust has been emplaced as ophiolites (Coleman 1977), thereby avoiding subduction, and no crust older than -200 Myr survives in the modern oceans. This would appear to limit the degree to which basin evolution can depend on external tectonic ev ...
... 0.001 per cent of the total volume of Phanerozoic ocean crust has been emplaced as ophiolites (Coleman 1977), thereby avoiding subduction, and no crust older than -200 Myr survives in the modern oceans. This would appear to limit the degree to which basin evolution can depend on external tectonic ev ...
Collision of continental corner from 3
... In the initial model setup, the overriding plate is homogeneous continent in the transverse z-direction. The subducting plate is composed of half continental (328 km wide) and half oceanic (328 km wide) lithospheres in z-direction (Fig. 1a), behind the oceanic-only subducting plate (656 km in z-dire ...
... In the initial model setup, the overriding plate is homogeneous continent in the transverse z-direction. The subducting plate is composed of half continental (328 km wide) and half oceanic (328 km wide) lithospheres in z-direction (Fig. 1a), behind the oceanic-only subducting plate (656 km in z-dire ...
A global-scale plate reorganization event at 105−100Ma
... A major plate reorganization is postulated to have occurred at approximately 100 Ma. However, this reorganization has received limited attention, despite being associated with the most prominent suite of fracture zone bends on the planet and many other geological events. We investigate tectonic even ...
... A major plate reorganization is postulated to have occurred at approximately 100 Ma. However, this reorganization has received limited attention, despite being associated with the most prominent suite of fracture zone bends on the planet and many other geological events. We investigate tectonic even ...
Morphology and magnetic survey of the Rivera
... to the present day Galapogos triple junction (Lonsdale, 1988). The divergence between the Rivera and Cocos plates is proposed by Bandy (1992) to be the result of the ridge-trench collision off the southern tip of Baja California at about 8 Ma (Lonsdale, 1991) and subsequent pivoting of the Rivera pl ...
... to the present day Galapogos triple junction (Lonsdale, 1988). The divergence between the Rivera and Cocos plates is proposed by Bandy (1992) to be the result of the ridge-trench collision off the southern tip of Baja California at about 8 Ma (Lonsdale, 1991) and subsequent pivoting of the Rivera pl ...
Global Tectonics - dynamicearth.de
... A defining characteristic of the cratonic mantle lithosphere is a seismic velocity that is faster than normal subcontinental mantle to depths of at least 200 km and locally to depths of 250–300 km (Plate 11.1b,c between pp. 244 and 245). Many Proterozoic belts lack these fast velocity anomalies at s ...
... A defining characteristic of the cratonic mantle lithosphere is a seismic velocity that is faster than normal subcontinental mantle to depths of at least 200 km and locally to depths of 250–300 km (Plate 11.1b,c between pp. 244 and 245). Many Proterozoic belts lack these fast velocity anomalies at s ...
i13 Drift versus land bridges Mesosaurus > - e
... equatorial portion of the ridge indicates a former landmass 5 was moot given the antecedent 1937 discovery by Otto-Ernst Radczewski of large numbers of wind-transported diatoms in eolian dust.6 Faunal evidence of a connection between southern Africa and South America was accounted for by Bailey Will ...
... equatorial portion of the ridge indicates a former landmass 5 was moot given the antecedent 1937 discovery by Otto-Ernst Radczewski of large numbers of wind-transported diatoms in eolian dust.6 Faunal evidence of a connection between southern Africa and South America was accounted for by Bailey Will ...
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.