The westward drift of the lithosphere
... Assuming an active pull from only that part of a slab between depths of 50 km and 350 km, and considering for example the Marianas slab, the following concerns can be envisaged. The negative buoyancy of an ~300-km-long slab should be able to pull the 10,000-km-long Pacific plate, overcoming the fric ...
... Assuming an active pull from only that part of a slab between depths of 50 km and 350 km, and considering for example the Marianas slab, the following concerns can be envisaged. The negative buoyancy of an ~300-km-long slab should be able to pull the 10,000-km-long Pacific plate, overcoming the fric ...
Influence of convergent plate boundaries on upper mantle flow and
... such behavior with a sound model based on the forces that drive mantle motion. To gain insight into the observations, we systematically investigate flow patterns around the cold downwelling sheets associated with consumed plate material in a three-dimensional numerical mantle convection model. First ...
... such behavior with a sound model based on the forces that drive mantle motion. To gain insight into the observations, we systematically investigate flow patterns around the cold downwelling sheets associated with consumed plate material in a three-dimensional numerical mantle convection model. First ...
Dismantling the Deep Earth: Geochemical
... Large dataset, so filter it to include only samples that best represent the high 3He/4He mantle: A.) Interested in the 87Sr/86Sr (and Nd, Pb) of only the high 3He/4He mantle, so examine only the lavas with the highest 3He/4He from hotspots that have high 3He/4He. B.) High 3He/4He lavas from some env ...
... Large dataset, so filter it to include only samples that best represent the high 3He/4He mantle: A.) Interested in the 87Sr/86Sr (and Nd, Pb) of only the high 3He/4He mantle, so examine only the lavas with the highest 3He/4He from hotspots that have high 3He/4He. B.) High 3He/4He lavas from some env ...
P corner, Japan-Kurile arc-arc junction Kei Katsumata, Naoto Wada, and Minoru Kasahara
... Katsumata et al. (2003) estimated the plate boundary with hypocentral distribution, we did not assume this model in our tomography. We will compare Katsumata’s model with the seismic activity is very high down to the upper mantle velocity structures in this study. due to the collision between the Ku ...
... Katsumata et al. (2003) estimated the plate boundary with hypocentral distribution, we did not assume this model in our tomography. We will compare Katsumata’s model with the seismic activity is very high down to the upper mantle velocity structures in this study. due to the collision between the Ku ...
The thermal effects of steady-state slab
... recent extension. Indeed, to produce arc magmas, geochemical analyses suggest that temperatures >1200 jC are required in the mantle wedge [1,2]. The observed high temperatures are contradictory to the expected cooling effects of a subducting plate, which represents a substantial heat sink. Many stud ...
... recent extension. Indeed, to produce arc magmas, geochemical analyses suggest that temperatures >1200 jC are required in the mantle wedge [1,2]. The observed high temperatures are contradictory to the expected cooling effects of a subducting plate, which represents a substantial heat sink. Many stud ...
Three-dimensional numerical models of flat slab subduction and the
... models allows for the portion of south-central Alaska between the Denali fault and the trench to partially decouple from the rest of North America, forming an independently moving region that correlates to what has been described from geologic and geodetic studies as the Wrangell block. The motion o ...
... models allows for the portion of south-central Alaska between the Denali fault and the trench to partially decouple from the rest of North America, forming an independently moving region that correlates to what has been described from geologic and geodetic studies as the Wrangell block. The motion o ...
Chapter 14 The Ocean Floor
... Deep-Ocean Trenches Deep-ocean trenches are long, narrow creases in the ocean floor that form the deepest parts of the ocean. Most trenches are located along the margins of the Pacific Ocean, and many exceed 10,000 meters in depth. A portion of one trench—the Challenger Deep in the Mariana Trench—ha ...
... Deep-Ocean Trenches Deep-ocean trenches are long, narrow creases in the ocean floor that form the deepest parts of the ocean. Most trenches are located along the margins of the Pacific Ocean, and many exceed 10,000 meters in depth. A portion of one trench—the Challenger Deep in the Mariana Trench—ha ...
Equatorial ocean circulation in an extremely warm climate
... downward arrows indicate the age and location of the oldest sediments recovered in piston cores taken along the transect. This package can be traced throughout the length of the 56 Ma crustal transect (Figure 1). These high amplitude reflections are thought to represent carbonate-rich sediments depo ...
... downward arrows indicate the age and location of the oldest sediments recovered in piston cores taken along the transect. This package can be traced throughout the length of the 56 Ma crustal transect (Figure 1). These high amplitude reflections are thought to represent carbonate-rich sediments depo ...
7. plate tectonic evolution of the cocos
... Coiba Ridge south of Panama has been suggested to have been formed not as a hotspot trace but rather by uplift beside a long meridional transform fault during the late Miocene and Pliocene (Lonsdale and Klitgord, 1978). Its origin, however, remains unclear because of the lack of data. The Carnegie R ...
... Coiba Ridge south of Panama has been suggested to have been formed not as a hotspot trace but rather by uplift beside a long meridional transform fault during the late Miocene and Pliocene (Lonsdale and Klitgord, 1978). Its origin, however, remains unclear because of the lack of data. The Carnegie R ...
ARCHITECTURE OF CONTINENTAL RIFTS Author: Susanne
... If the rising plume approaches the lithosphere, the head begins to replace the thin boundary layer of surrounding mantle material and is heated by conduction until its temperature and density becomes comparable to that of the plume. The heat transfer mechanism changes from predominantly convective t ...
... If the rising plume approaches the lithosphere, the head begins to replace the thin boundary layer of surrounding mantle material and is heated by conduction until its temperature and density becomes comparable to that of the plume. The heat transfer mechanism changes from predominantly convective t ...
The Westward Drift of the Lithosphere: A rotational drag?
... magnitude of the slab pull are based on a number of assumptions such as a homogeneous upper mantle geochemistry, and a thermally- and phase changes-driven negative buoyancy. However, the mineralogical constraints of the upper mantle are quite weak, and focal mechanisms indicate that slabs undergo do ...
... magnitude of the slab pull are based on a number of assumptions such as a homogeneous upper mantle geochemistry, and a thermally- and phase changes-driven negative buoyancy. However, the mineralogical constraints of the upper mantle are quite weak, and focal mechanisms indicate that slabs undergo do ...
Hoffman2013_Cordille.. - Department of Earth Sciences
... the Cascades and Mexican volcanic arcs, and which formerly subducted along the entire west coast, where extinct and deeply-eroded volcanic arcs are represented by the Mesozoic Sierra Nevada, Peninsular Ranges, Idaho and Coast Mountains batholiths. In the North Pacific, the plate has been almost enti ...
... the Cascades and Mexican volcanic arcs, and which formerly subducted along the entire west coast, where extinct and deeply-eroded volcanic arcs are represented by the Mesozoic Sierra Nevada, Peninsular Ranges, Idaho and Coast Mountains batholiths. In the North Pacific, the plate has been almost enti ...
The ocean-continent transition in the uniform lithospheric stretching
... The reason why the transition from continental lithosphere stretching to oceanic accretion should occur for a given stretching factor /3 was, however, not discussed in detail by Le Pichon & Sibuet (1981). They did mention the probable role played by the increase in the amount of partial melting as t ...
... The reason why the transition from continental lithosphere stretching to oceanic accretion should occur for a given stretching factor /3 was, however, not discussed in detail by Le Pichon & Sibuet (1981). They did mention the probable role played by the increase in the amount of partial melting as t ...
Origin and evolution of the lower crust in magmatic arcs and
... dense cumulates from the base of arc crust, foundering into less dense, underlying mantle peridotite, is likely, as supported by geochemical evidence from Talkeetna and Kohistan. Relamination of buoyant, subducting material—during sediment subduction, subduction erosion, arc-arc collision, and conti ...
... dense cumulates from the base of arc crust, foundering into less dense, underlying mantle peridotite, is likely, as supported by geochemical evidence from Talkeetna and Kohistan. Relamination of buoyant, subducting material—during sediment subduction, subduction erosion, arc-arc collision, and conti ...
PDF - Wiley Online Library
... plates/mantle system, which involve predominantly horizontal shear over Myr periods. The asthenospheric viscosity impacts on the circulation planform of mantle convection [e.g., Bunge et al., 1996], on the pattern of plume hot spots activity recorded on the aging ocean floor [Boschi et al., 2007]; an ...
... plates/mantle system, which involve predominantly horizontal shear over Myr periods. The asthenospheric viscosity impacts on the circulation planform of mantle convection [e.g., Bunge et al., 1996], on the pattern of plume hot spots activity recorded on the aging ocean floor [Boschi et al., 2007]; an ...
Manea et al., 2006. - Centro de Geociencias
... Fig. 2. Thermal models for Central Mexico from Manea et al. (2005). The focal mechanisms represent the intraplate seismicity with magnitude greater than 5.0 (Mw) from Fig. 1. Brown clouds of hypocenters (Kostoglodov et al., 1996) beneath the coast denote the smaller magnitude seismicity associated p ...
... Fig. 2. Thermal models for Central Mexico from Manea et al. (2005). The focal mechanisms represent the intraplate seismicity with magnitude greater than 5.0 (Mw) from Fig. 1. Brown clouds of hypocenters (Kostoglodov et al., 1996) beneath the coast denote the smaller magnitude seismicity associated p ...
Twin Hotspot Tracks and Ridge Jumps
... et al ; Barckhausen et al ) It has been demonstrated that the products of the hotspot volcanism covered a complex pattern of oceanic crust formed at three subsequently active symmetric spreading systems of different orientation The identified extinct spreading systems represent precur ...
... et al ; Barckhausen et al ) It has been demonstrated that the products of the hotspot volcanism covered a complex pattern of oceanic crust formed at three subsequently active symmetric spreading systems of different orientation The identified extinct spreading systems represent precur ...
Lithosphere and Asthenosphere
... 3. How do the lithosphere and asthenosphere differ? 4. If the lithosphere is resting on the asthenosphere and you put a lot of weight on the lithosphere, say ice in a glacier, how would the lithosphere respond? ...
... 3. How do the lithosphere and asthenosphere differ? 4. If the lithosphere is resting on the asthenosphere and you put a lot of weight on the lithosphere, say ice in a glacier, how would the lithosphere respond? ...
The African Plate: A history of oceanic crust accretion and
... serpentinized) continental mantle and isolated blocks of extended continental crust exist for at least tens of kilometers (e.g., Manatschal, 2004), a clear boundary between extended continental crust and oceanic crust is almost impossible to identify. In those cases, the COB is rather defined as the ...
... serpentinized) continental mantle and isolated blocks of extended continental crust exist for at least tens of kilometers (e.g., Manatschal, 2004), a clear boundary between extended continental crust and oceanic crust is almost impossible to identify. In those cases, the COB is rather defined as the ...
Structure and Serpentinization of the Subducting Cocos Plate
... flexural bending of downgoing plates near deep sea trenches. Analyses of bathymetry and gravity profiles show that bending stresses can exceed the strength of the oceanic lithosphere, causing a reduction of the flexural rigidity near convergent plate boundaries [Caldwell et al., 1976]. Compression i ...
... flexural bending of downgoing plates near deep sea trenches. Analyses of bathymetry and gravity profiles show that bending stresses can exceed the strength of the oceanic lithosphere, causing a reduction of the flexural rigidity near convergent plate boundaries [Caldwell et al., 1976]. Compression i ...
Sea-floor basement morphology: Distinguishing
... “basement topography” once buried under sediments—that is most readily characterized at high spatial resolution by multibeam bathymetry, sidescan sonar, or reflection seismology. (Where oceanic crust emerges above sea level, optic and radar imaging reveal this upper crustal interface at even greater ...
... “basement topography” once buried under sediments—that is most readily characterized at high spatial resolution by multibeam bathymetry, sidescan sonar, or reflection seismology. (Where oceanic crust emerges above sea level, optic and radar imaging reveal this upper crustal interface at even greater ...
Unraveling the Tapestry of Ocean Crust
... “float” high atop the viscous mantle, forming dry land. Conversely, dense oceanic crust does not “float” as high—forming lower-lying ocean basins. As oceanic crust cools, it becomes denser and ultimately sinks back into the mantle under its own weight after about 200 million years. Earth’s continent ...
... “float” high atop the viscous mantle, forming dry land. Conversely, dense oceanic crust does not “float” as high—forming lower-lying ocean basins. As oceanic crust cools, it becomes denser and ultimately sinks back into the mantle under its own weight after about 200 million years. Earth’s continent ...
as a PDF
... the case of the Bicol arc east of the Philippines, analysed lavas lie within error of the equiline ( gure 3b), and so either ®uid addition did not result in U{Th disequilibrium in this instance or else the time since U addition is 350 kyr. In total, about 15 arcs have now been studied for U{Th dise ...
... the case of the Bicol arc east of the Philippines, analysed lavas lie within error of the equiline ( gure 3b), and so either ®uid addition did not result in U{Th disequilibrium in this instance or else the time since U addition is 350 kyr. In total, about 15 arcs have now been studied for U{Th dise ...
Constraints on shallow mantle viscosity from morphology and
... unconstrained magma column will reach a shallower level than zt. Therefore, zm is conceptualized as the potential height of the top of magma column relative to zt and is called magma top. For instance, zm of 200 m means that internal pressure can push magma up to 200 m above the dike top. z0 is the ...
... unconstrained magma column will reach a shallower level than zt. Therefore, zm is conceptualized as the potential height of the top of magma column relative to zt and is called magma top. For instance, zm of 200 m means that internal pressure can push magma up to 200 m above the dike top. z0 is the ...
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.