Inclusions in Sublithospheric Diamonds
... Gasparik 2002). However, plate tectonics, the standard model in Earth sciences, provides a mechanism in accord with the petrological, geochemical, and geophysical constraints on the composition of Earth’s mantle and the evidence against the long-term survival of extreme compositional stratification. ...
... Gasparik 2002). However, plate tectonics, the standard model in Earth sciences, provides a mechanism in accord with the petrological, geochemical, and geophysical constraints on the composition of Earth’s mantle and the evidence against the long-term survival of extreme compositional stratification. ...
Free Sample
... 3. How does fossil evidence support continental drift? ANS: The distribution of fossils is such that it would be impossible for the plants and animals not to have lived in contiguous land areas. Glossopteris seeds are too heavy to be dispersed by wind and would not have remained viable if they had t ...
... 3. How does fossil evidence support continental drift? ANS: The distribution of fossils is such that it would be impossible for the plants and animals not to have lived in contiguous land areas. Glossopteris seeds are too heavy to be dispersed by wind and would not have remained viable if they had t ...
Melting Relations of MORB^Sediment Me
... magmas produced by 50% melting. However, according to heat transfer models (Petford & Gallagher, 2001; Annen & Sparks, 2002), the heat provided by the intrusion of wet basalt at temperatures of 1100^12408C (Pichavant et al., 2002) in the lower crust is not sufficient to produce high melt fractions f ...
... magmas produced by 50% melting. However, according to heat transfer models (Petford & Gallagher, 2001; Annen & Sparks, 2002), the heat provided by the intrusion of wet basalt at temperatures of 1100^12408C (Pichavant et al., 2002) in the lower crust is not sufficient to produce high melt fractions f ...
Plate Tectonics Teacher Assessment User Manual
... This knowledge refers strictly to the science content, with no other elements of what a teacher would need to know in order to relate the content to students. 2. Knowledge that alternative frameworks for thinking about the content exist When teachers have deep knowledge of disciplinary content and r ...
... This knowledge refers strictly to the science content, with no other elements of what a teacher would need to know in order to relate the content to students. 2. Knowledge that alternative frameworks for thinking about the content exist When teachers have deep knowledge of disciplinary content and r ...
Origins of the plume hypothesis and some of its
... oceanic lithosphere. The velocity is upward and no material recirculates. (2) Much of the melt segregates and ascends. (3) The material is homogeneous and the composition is the same beneath hotspots and normal ridges. The validity of these assumptions and alternatives are potentially detectable fro ...
... oceanic lithosphere. The velocity is upward and no material recirculates. (2) Much of the melt segregates and ascends. (3) The material is homogeneous and the composition is the same beneath hotspots and normal ridges. The validity of these assumptions and alternatives are potentially detectable fro ...
Nitrogen concentration and d N of altered oceanic crust obtained on
... and 1149 and petrological and geochemical information regarding the AOC from those sites have been provided elsewhere (e.g., Plank et al., 2000; Alt and Teagle, 2003; Kelley et al., 2003), and are only briefly discussed here. The IBM system is formed by subduction of the Pacific plate beneath the Phil ...
... and 1149 and petrological and geochemical information regarding the AOC from those sites have been provided elsewhere (e.g., Plank et al., 2000; Alt and Teagle, 2003; Kelley et al., 2003), and are only briefly discussed here. The IBM system is formed by subduction of the Pacific plate beneath the Phil ...
Geosphere - Do plumes exist?
... reduced subsidence; sediments were deposited at shelf or outer shelf conditions instead of at 2–5 km depth around the time of breakup (Péron-Pinvidic and Manatschal, 2009). Such uplift prior to breakup results in lateral variations in the lithospheric potential energy, which contributes to deviatori ...
... reduced subsidence; sediments were deposited at shelf or outer shelf conditions instead of at 2–5 km depth around the time of breakup (Péron-Pinvidic and Manatschal, 2009). Such uplift prior to breakup results in lateral variations in the lithospheric potential energy, which contributes to deviatori ...
Upper mantle flow in the western Mediterranean
... Massif Central, where 30 km continental crust deformed during the Variscan orogeny outcrop. The lithospheric base, generally around 80–90 km deep, is interpreted to be much shallower (around 50 km) below the Cenozoic Massif Central alkaline volcanic province. Since the crust is not thinned according ...
... Massif Central, where 30 km continental crust deformed during the Variscan orogeny outcrop. The lithospheric base, generally around 80–90 km deep, is interpreted to be much shallower (around 50 km) below the Cenozoic Massif Central alkaline volcanic province. Since the crust is not thinned according ...
Velocity increase in the uppermost oceanic crust of subducting
... of the seismic sources (shaded area in Figure 1a) which is perpendicular to the direction of subduction, were interpreted as trapped P and S waves propagating along the low-velocity oceanic crust of the Philippine Sea plate. Figure 1b shows the vertical velocity seismograms recorded at the Hi-net st ...
... of the seismic sources (shaded area in Figure 1a) which is perpendicular to the direction of subduction, were interpreted as trapped P and S waves propagating along the low-velocity oceanic crust of the Philippine Sea plate. Figure 1b shows the vertical velocity seismograms recorded at the Hi-net st ...
Mechanisms for the Origin of Mid-Ocean Ridge Axial Topography: Implications
... the Vening Meinesz [1950] model for rifts. In its application to mid-ocean ridges, the model does not explain the amplitude and width of the ridge axis depressionin terms of other physical variables, such as extension rate and plate thickness. Furthermore,a variety of evidencesuggeststhat the lithos ...
... the Vening Meinesz [1950] model for rifts. In its application to mid-ocean ridges, the model does not explain the amplitude and width of the ridge axis depressionin terms of other physical variables, such as extension rate and plate thickness. Furthermore,a variety of evidencesuggeststhat the lithos ...
North America Dynamics and Western US Tectonics
... view of the forces responsible for plate motion has edge forces driving rigid plates over a weak and relatively static asthenosphere that acts to resist plate motion. Recently, this view has been challenged by some global geodynamicists, who advocate a model with mantle flow (driven primarily by oce ...
... view of the forces responsible for plate motion has edge forces driving rigid plates over a weak and relatively static asthenosphere that acts to resist plate motion. Recently, this view has been challenged by some global geodynamicists, who advocate a model with mantle flow (driven primarily by oce ...
Crustal contributions to arc magmatism in the Andes of Central Chile
... Downdip transport time from trench to arc at the present convergence rate is only ~ 3 Ma. The slight age differences along the segment of the relatively young subducted lithosphere are unlikely to result in significant variations of thermal and mechanical properties within the downgoing plate (Worte ...
... Downdip transport time from trench to arc at the present convergence rate is only ~ 3 Ma. The slight age differences along the segment of the relatively young subducted lithosphere are unlikely to result in significant variations of thermal and mechanical properties within the downgoing plate (Worte ...
An analysis of young ocean depth, gravity and global residual
... Since then, a number of physical explanations have been put forward for this flattening. These include (1) the addition of heat from convective instability underneath the rigid mechanical boundary layer (Parsons & McKenzie 1978); (2) radioactive heating in the upper part of the mantle (Forsyth 1977) ...
... Since then, a number of physical explanations have been put forward for this flattening. These include (1) the addition of heat from convective instability underneath the rigid mechanical boundary layer (Parsons & McKenzie 1978); (2) radioactive heating in the upper part of the mantle (Forsyth 1977) ...
ARTICLE IN PRESS - Do plumes exist?
... from few exceptions, the subduction hinge converges toward the upper plate more frequently along E- or NE-directed subduction zone, whereas it mainly diverges from the upper plate along W-directed subduction zones accompanying backarc extension. Before collision, orogen growth occurs mostly at the e ...
... from few exceptions, the subduction hinge converges toward the upper plate more frequently along E- or NE-directed subduction zone, whereas it mainly diverges from the upper plate along W-directed subduction zones accompanying backarc extension. Before collision, orogen growth occurs mostly at the e ...
Chapter 7. Convection and Complexity
... Melting occurs where the geotherms intersect the mantle solidus . For a dry peridotite mantle, the geotherm (conduction gradient) in a region of high surface heatflow, 100 mW/m 2 , intersects the solidus a t ~ 3 0 km depth. Surface heat flows of 100 mWjm 2 or greater occur only at or near midocean r ...
... Melting occurs where the geotherms intersect the mantle solidus . For a dry peridotite mantle, the geotherm (conduction gradient) in a region of high surface heatflow, 100 mW/m 2 , intersects the solidus a t ~ 3 0 km depth. Surface heat flows of 100 mWjm 2 or greater occur only at or near midocean r ...
Geophysical Journal International - ORCA
... mm yr−1 (Wallace et al. 2012). Orange square marks location of Morere thermal springs from which gases with an abnormally high mantle component have been measured (Reyes et al. 2010). Grey circle with cross is location of Hawke Bay-1 well mentioned in text. (c) (top) interpreted seismic profile 05CM ...
... mm yr−1 (Wallace et al. 2012). Orange square marks location of Morere thermal springs from which gases with an abnormally high mantle component have been measured (Reyes et al. 2010). Grey circle with cross is location of Hawke Bay-1 well mentioned in text. (c) (top) interpreted seismic profile 05CM ...
Imag(in)ing the continental lithosphere
... 1995), although most tomographic images of the craton show high velocity roots extending to at least 200 km depth, and in some cases to depths greater than 300 km (e.g., Grand, 1994; Van der Lee and Nolet, 1997). Since body wave tomographic images smear anomalies along ray paths and the angular band ...
... 1995), although most tomographic images of the craton show high velocity roots extending to at least 200 km depth, and in some cases to depths greater than 300 km (e.g., Grand, 1994; Van der Lee and Nolet, 1997). Since body wave tomographic images smear anomalies along ray paths and the angular band ...
Tectonic speed limits from plate kinematic reconstructions (PDF
... tracked through time (Table S1). Continental RMS velocity and areas are recorded, as well as the area of Phanerozoic, Proterozoic and Archean lithosphere based on the tectonothermal ages modelled by Artemieva (2006). Although our plate motion model does not include continental deformation, conservat ...
... tracked through time (Table S1). Continental RMS velocity and areas are recorded, as well as the area of Phanerozoic, Proterozoic and Archean lithosphere based on the tectonothermal ages modelled by Artemieva (2006). Although our plate motion model does not include continental deformation, conservat ...
Evidence for plate tectonics, part 1
... The results of plate tectonic processes abound, from the mighty folds of the ancient and well worn Appalachians, the majestic escarpments of the East African Rift Valley and the Palisades of the Hudson River, and the volcanoes that imperil cities in Iceland, Indonesia, Japan and Mexico. Even idylli ...
... The results of plate tectonic processes abound, from the mighty folds of the ancient and well worn Appalachians, the majestic escarpments of the East African Rift Valley and the Palisades of the Hudson River, and the volcanoes that imperil cities in Iceland, Indonesia, Japan and Mexico. Even idylli ...
Continental crust generated in oceanic arcs
... within older continental crust (for example, Andes, Cascades, New Zealand, Indonesia, Japan) to ensure that the locations evaluated in this study are forming from juvenile sources and not inheriting geochemical signatures from pre-existing continental material. Figure 4 shows that average compositio ...
... within older continental crust (for example, Andes, Cascades, New Zealand, Indonesia, Japan) to ensure that the locations evaluated in this study are forming from juvenile sources and not inheriting geochemical signatures from pre-existing continental material. Figure 4 shows that average compositio ...
- Wiley Online Library
... discrete shear zone beneath the overriding plate. Following this initial stage of subduction, the subducting lower crust and mantle lithosphere can retreat from the collision zone, permitting the sub-lithospheric mantle to upwell and intrude the overriding plate. As a result, the lower crust and man ...
... discrete shear zone beneath the overriding plate. Following this initial stage of subduction, the subducting lower crust and mantle lithosphere can retreat from the collision zone, permitting the sub-lithospheric mantle to upwell and intrude the overriding plate. As a result, the lower crust and man ...
mid-ocean ridges: mantle convection
... rigid to convection and is the newly created edge of the tectonic plate. As the lithosphere moves away from the ridge, it thickens via additional cooling, becomes denser, and sinks deeper into the underlying ductile asthenosphere. This aging process of the plates causes the oceans to double in depth ...
... rigid to convection and is the newly created edge of the tectonic plate. As the lithosphere moves away from the ridge, it thickens via additional cooling, becomes denser, and sinks deeper into the underlying ductile asthenosphere. This aging process of the plates causes the oceans to double in depth ...
AZU_TD_BOX206_E9791_
... driving forces include ridge-push, slab-pull and resis tive drag, and other forces which are not modeled but are described such as transform fault resistance, radial push from hot spots and distant forces from other plates. Thirty different models represent combinations of the plate-driving forces ...
... driving forces include ridge-push, slab-pull and resis tive drag, and other forces which are not modeled but are described such as transform fault resistance, radial push from hot spots and distant forces from other plates. Thirty different models represent combinations of the plate-driving forces ...
Far-reaching transient motions after Mojave
... transient deformation throughout southern California and into Nevada, more than 200 km from the epicenter. Unlike previous postseismic observations in which trade-offs between postseismic mechanisms and the depth of flow lead to non-unique solutions, this deformation pattern can only be explained by ...
... transient deformation throughout southern California and into Nevada, more than 200 km from the epicenter. Unlike previous postseismic observations in which trade-offs between postseismic mechanisms and the depth of flow lead to non-unique solutions, this deformation pattern can only be explained by ...
Continental breakup and the onset of ultraslow seafloor spreading
... into and serpentinize the upper mantle. Detachment tectonics above this weak material formed the S reflection and unroofed a peridotite ridge. Breakup just west of the peridotite ridge isolated it on the Galicia Bank margin and led to stage 2, where mantle melts reached the surface and seafloor spre ...
... into and serpentinize the upper mantle. Detachment tectonics above this weak material formed the S reflection and unroofed a peridotite ridge. Breakup just west of the peridotite ridge isolated it on the Galicia Bank margin and led to stage 2, where mantle melts reached the surface and seafloor spre ...
Oceanic trench
The oceanic trenches are hemispheric-scale long but narrow topographic depressions of the sea floor. They are also the deepest parts of the ocean floor. Oceanic trenches are a distinctive morphological feature of convergent plate boundaries, along which lithospheric plates move towards each other at rates that vary from a few mm to over ten cm per year. A trench marks the position at which the flexed, subducting slab begins to descend beneath another lithospheric slab. Trenches are generally parallel to a volcanic island arc, and about 200 km (120 mi) from a volcanic arc. Oceanic trenches typically extend 3 to 4 km (1.9 to 2.5 mi) below the level of the surrounding oceanic floor. The greatest ocean depth to be sounded is in the Challenger Deep of the Mariana Trench, at a depth of 11,034 m (36,201 ft) below sea level. Oceanic lithosphere moves into trenches at a global rate of about 3 km2/yr.