The thermal structure of subduction zones constrained by seismic
... It is more realistic to model the mantle of the wedge as a medium with strongly temperature- and stress-dependent rheology, which is characteristic of the deformation of the dominant minerals under mantle conditions. In Figure 5b we show the temperature field obtained with rheology based on disloca ...
... It is more realistic to model the mantle of the wedge as a medium with strongly temperature- and stress-dependent rheology, which is characteristic of the deformation of the dominant minerals under mantle conditions. In Figure 5b we show the temperature field obtained with rheology based on disloca ...
Kimberlite - Miami University
... y guess is that the number of mineral collectors who recognize the term kimberlite is far out of proportion to the abundance of this unusual rock type. This, of course, would be the result of the enchanting treasure found in many kimberlites: diamonds! Kimberlite is an igneous rock that is chemicall ...
... y guess is that the number of mineral collectors who recognize the term kimberlite is far out of proportion to the abundance of this unusual rock type. This, of course, would be the result of the enchanting treasure found in many kimberlites: diamonds! Kimberlite is an igneous rock that is chemicall ...
Worldwide distribution of ages of the continental lithosphere derived
... It has long been known that continental regions of different age have different seismic properties: the older the lithosphere, the greater the velocity. Here we ask whether we can obtain a more formal relationship between seismological observations and the age of continents. The deep structure of co ...
... It has long been known that continental regions of different age have different seismic properties: the older the lithosphere, the greater the velocity. Here we ask whether we can obtain a more formal relationship between seismological observations and the age of continents. The deep structure of co ...
Upper-mantle S-velocity structure of central and western South
... 3-D S-velocity structure of the upper mantle of western and central South America using vertical component seismograms recorded by South American stations. These seismograms are from a mix of relatively uniformly distributed, permanent stations and from concentrated groups of stations from temporary ...
... 3-D S-velocity structure of the upper mantle of western and central South America using vertical component seismograms recorded by South American stations. These seismograms are from a mix of relatively uniformly distributed, permanent stations and from concentrated groups of stations from temporary ...
Imaging the Gutenberg Seismic Discontinuity beneath the Oceanic
... 660 km discontinuities are from phase changes in the mineral olivine. Other discontinuities like the one found at the mantle-outer core boundary is from the transition of rock to liquid metal. However, there are several discontinuities other than those listed above that do not necessarily have a cle ...
... 660 km discontinuities are from phase changes in the mineral olivine. Other discontinuities like the one found at the mantle-outer core boundary is from the transition of rock to liquid metal. However, there are several discontinuities other than those listed above that do not necessarily have a cle ...
Beyond Plate Tectonics: “Plate” Dynamics
... One concept that will surely cause some geologists to doubt this model is the manner in which magma gets to the magma chamber from a distance as great as 500+ km towards the interior of the plate. The answer is remarkably simple. When surging occurs (see below), the boundary between the surging plat ...
... One concept that will surely cause some geologists to doubt this model is the manner in which magma gets to the magma chamber from a distance as great as 500+ km towards the interior of the plate. The answer is remarkably simple. When surging occurs (see below), the boundary between the surging plat ...
Becker, TW - Semantic Scholar
... To examine the mantle drag contributions due to different buoyancy force distributions, we use 3-D, spherical mantle flow computations (Hager and O'Connell, 1981). To model mantle circulation, we solve the infinite Prandtl number, Stokes equation for incompressible fluid flow (Boussinesq approximation) ...
... To examine the mantle drag contributions due to different buoyancy force distributions, we use 3-D, spherical mantle flow computations (Hager and O'Connell, 1981). To model mantle circulation, we solve the infinite Prandtl number, Stokes equation for incompressible fluid flow (Boussinesq approximation) ...
Chapter 7 Plate Tectonics
... The layer of the Earth between the crust and the core is the mantle. The mantle is much thicker than the crust. It contains most of the Earth’s mass. The mantle contains more magnesium and less aluminum than the crust. This makes the mantle denser than the crust. No one has ever visited the mantle. ...
... The layer of the Earth between the crust and the core is the mantle. The mantle is much thicker than the crust. It contains most of the Earth’s mass. The mantle contains more magnesium and less aluminum than the crust. This makes the mantle denser than the crust. No one has ever visited the mantle. ...
Evolution of young oceanic lithosphere and the meaning of seafloor
... depth, respectively. The model spans from the seafloor (z = 0) to the depth of 300 km, which is sufficiently deep to model half-space cooling for the duration of 100 Myr. The above equation is solved with a finite difference approximation, using the vertical spacing of 1 km and the time step of 5000 year ...
... depth, respectively. The model spans from the seafloor (z = 0) to the depth of 300 km, which is sufficiently deep to model half-space cooling for the duration of 100 Myr. The above equation is solved with a finite difference approximation, using the vertical spacing of 1 km and the time step of 5000 year ...
Geochemistry of near-EPR seamounts: importance of source vs
... northern EPR region results from melting-induced mixing of a two-component mantle with the enriched (easily melted) component dispersed as physically distinct domains in a more depleted (refractory) matrix prior to the major melting events. The data also allow the conclusion that recycled oceanic cr ...
... northern EPR region results from melting-induced mixing of a two-component mantle with the enriched (easily melted) component dispersed as physically distinct domains in a more depleted (refractory) matrix prior to the major melting events. The data also allow the conclusion that recycled oceanic cr ...
Plate bending at subduction zones
... reasonable approximation given the magnitude of change in the other terms. Consequently, we determine the plate motion by requiring ψ − ϕb to be stationary with respect to changes in the direction of plate motion. This implies that the direction of plate motion maximizes the work done by gravity, su ...
... reasonable approximation given the magnitude of change in the other terms. Consequently, we determine the plate motion by requiring ψ − ϕb to be stationary with respect to changes in the direction of plate motion. This implies that the direction of plate motion maximizes the work done by gravity, su ...
Driving mechanism and 3-D circulation of plate tectonics
... subduction-free Atlantic widens by slow mid-ocean spreading. These and other firstorder features of global tectonics cannot be explained by conventional models. The behavior of arcs and the common presence of forearc basins on the uncrumpled thin leading edges of advancing arcs and continents are am ...
... subduction-free Atlantic widens by slow mid-ocean spreading. These and other firstorder features of global tectonics cannot be explained by conventional models. The behavior of arcs and the common presence of forearc basins on the uncrumpled thin leading edges of advancing arcs and continents are am ...
S6E5e. Recognize that lithospheric plates constantly move and
... • Place your hands in front of you, side by side, with your palms facing the floor as shown in the picture. ...
... • Place your hands in front of you, side by side, with your palms facing the floor as shown in the picture. ...
Cascadia subduction slab heterogeneity revealed by three
... We highlight two features in this reflectivity model. First, the migration algorithm recovers the 410 km discontinuity approximately as a flat interface near 410 km depth. Second, east of 121°W longitude, a strong negative (blue) signal appears between 150 and 200 km depth. We identify this signal as ...
... We highlight two features in this reflectivity model. First, the migration algorithm recovers the 410 km discontinuity approximately as a flat interface near 410 km depth. Second, east of 121°W longitude, a strong negative (blue) signal appears between 150 and 200 km depth. We identify this signal as ...
Open File - Earth Science > Home
... A seismic wave moves at the following speeds through each layer: crust, 8 km/s; mantle, 12 km/s; outer core, 9.5 km/s; inner core, 10.5 km/s. How long would a seismic wave take to travel from Earth’s surface to its center? ...
... A seismic wave moves at the following speeds through each layer: crust, 8 km/s; mantle, 12 km/s; outer core, 9.5 km/s; inner core, 10.5 km/s. How long would a seismic wave take to travel from Earth’s surface to its center? ...
The role of lower continental crust and lithospheric mantle in the
... of lavas have relatively high 87 Sr/86 Sr (0.7043^0.7051), low 143 Nd/144 Nd (0.5124^0.5126), and are characterised by the least radiogenic Pb isotopic composition so far recorded in Italian (and European) Neogene-to-Recent mafic volcanic rocks (206 Pb/204 Pb = 17.55^18.01) (unradiogenic Pb volcanic ...
... of lavas have relatively high 87 Sr/86 Sr (0.7043^0.7051), low 143 Nd/144 Nd (0.5124^0.5126), and are characterised by the least radiogenic Pb isotopic composition so far recorded in Italian (and European) Neogene-to-Recent mafic volcanic rocks (206 Pb/204 Pb = 17.55^18.01) (unradiogenic Pb volcanic ...
Tomographic Pn velocity and anisotropy structure beneath
... Iranian Long Period Array (ILPA) located in northern Iran (Figure 1). The uncertainty of the Pn phase readings is less than one second. To include these data in our inversion we required a minimum of 10 different events per station and a minimum of 5 stations recording a single event. The larger qu ...
... Iranian Long Period Array (ILPA) located in northern Iran (Figure 1). The uncertainty of the Pn phase readings is less than one second. To include these data in our inversion we required a minimum of 10 different events per station and a minimum of 5 stations recording a single event. The larger qu ...
Partial delamination of continental mantle lithosphere, uplift
... Received 21 January 2000; revised 30 May 2000; accepted 16 June 2000 ...
... Received 21 January 2000; revised 30 May 2000; accepted 16 June 2000 ...
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... and the Driving Mechanism of Plate Tectonics Department of Geology a n d Geopbsics, University of California, Berkeley, California 94720 Tectonic features at the earth's surface can be used to test models for mantle return flow and to determine the geographic pattern of this flow. A model with shall ...
... and the Driving Mechanism of Plate Tectonics Department of Geology a n d Geopbsics, University of California, Berkeley, California 94720 Tectonic features at the earth's surface can be used to test models for mantle return flow and to determine the geographic pattern of this flow. A model with shall ...
MS Plate Tectonics
... The seafloor spreading hypothesis brought all of these observations together in the early 1960s. Hot mantle material rises up at mid-ocean ridges. The hot magma erupts as lava. The lava cools to form new seafloor. Later, more lava erupts at the ridge. The new lava pushes the seafloor that is at the ...
... The seafloor spreading hypothesis brought all of these observations together in the early 1960s. Hot mantle material rises up at mid-ocean ridges. The hot magma erupts as lava. The lava cools to form new seafloor. Later, more lava erupts at the ridge. The new lava pushes the seafloor that is at the ...
Seismic Earth. Array Analysis of Broadband Seismograms. Volume 157. Brochure
... Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 157. Seismology is one of the few means available to Earth scientists for probing the mechanical structure of the Earth's interior. The advent of modern seismic instrumentation at the end of the 19th cent ...
... Published by the American Geophysical Union as part of the Geophysical Monograph Series, Volume 157. Seismology is one of the few means available to Earth scientists for probing the mechanical structure of the Earth's interior. The advent of modern seismic instrumentation at the end of the 19th cent ...
Mantle plume
A mantle plume is a mechanism proposed in 1971 to explain volcanic regions of the earth that were not thought to be explicable by the then-new theory of plate tectonics. Some such volcanic regions lie far from tectonic plate boundaries, for example, Hawaii. Others represent unusually large-volume volcanism, whether on plate boundaries, e.g. Iceland, or basalt floods such as the Deccan or Siberian traps.A mantle plume is posited to exist where hot rock nucleates at the core-mantle boundary and rises through the Earth's mantle becoming a diapir in the Earth's crust. The currently active volcanic centers are known as ""hot spots"". In particular, the concept that mantle plumes are fixed relative to one another, and anchored at the core-mantle boundary, was thought to provide a natural explanation for the time-progressive chains of older volcanoes seen extending out from some such hot spots, such as the Hawaiian–Emperor seamount chain.The hypothesis of mantle plumes from depth is not universally accepted as explaining all such volcanism. It has required progressive hypothesis-elaboration leading to variant propositions such as mini-plumes and pulsing plumes. Another hypothesis for unusual volcanic regions is the ""Plate model"". This proposes shallower, passive leakage of magma from the mantle onto the Earth's surface where extension of the lithosphere permits it, attributing most volcanism to plate tectonic processes, with volcanoes far from plate boundaries resulting from intraplate extension.