2.03 Sampling Mantle Heterogeneity through Oceanic Basalts
... that chemical disequilibrium between grain centers and margins will persist during melting. Consequently, the melt will not be in equilibrium with the bulk residue for geologically reasonable melting times, if the equilibration occurs by volume diffusion alone. This means that the conclusions of Hof ...
... that chemical disequilibrium between grain centers and margins will persist during melting. Consequently, the melt will not be in equilibrium with the bulk residue for geologically reasonable melting times, if the equilibration occurs by volume diffusion alone. This means that the conclusions of Hof ...
Geologic Structures
... events that occurred in the past by observing changes occurring today. Sometimes this idea is summarized in the statement “The present is the key to the past.” For example, we can observe today each individual step that leads to the formation of sandstone. Even though it would take too long for us t ...
... events that occurred in the past by observing changes occurring today. Sometimes this idea is summarized in the statement “The present is the key to the past.” For example, we can observe today each individual step that leads to the formation of sandstone. Even though it would take too long for us t ...
Chemical Geodynamics - Woods Hole Oceanographic Institution
... see Figure 14]. The isotopic "variability" (amplitude ratio, or AR) ora given basalt suite (island, volcano, section of ridge, etc) is then expressed as a percentage of this total possible variation. Amplitude ratios for selected basalt suites are shown as a function of sampling scale length in Figu ...
... see Figure 14]. The isotopic "variability" (amplitude ratio, or AR) ora given basalt suite (island, volcano, section of ridge, etc) is then expressed as a percentage of this total possible variation. Amplitude ratios for selected basalt suites are shown as a function of sampling scale length in Figu ...
Becker, T. W. - The University of Texas at Austin
... lithospheric topography. Isostatic modeling based on these improved crustal thickness and offset estimates indicates that lithospheric thinning alone does not explain the anomalous Atlas topography. Instead, an upwelling component induced by a hot mantle anomaly is also required to support the Atlas ...
... lithospheric topography. Isostatic modeling based on these improved crustal thickness and offset estimates indicates that lithospheric thinning alone does not explain the anomalous Atlas topography. Instead, an upwelling component induced by a hot mantle anomaly is also required to support the Atlas ...
On the role of slab pull in the Cenozoic motion of the Pacific plate
... zone length [Conrad and Lithgow-Bertelloni, 2004]. This increase does not mirror an increase in plate speed as from M08, which is only oscillating between 9 and 6 cm/yr, increasing to >9 cm/yr at the present-day. A progressive increase in plate velocity during the Cenozoic is observed, conversely, i ...
... zone length [Conrad and Lithgow-Bertelloni, 2004]. This increase does not mirror an increase in plate speed as from M08, which is only oscillating between 9 and 6 cm/yr, increasing to >9 cm/yr at the present-day. A progressive increase in plate velocity during the Cenozoic is observed, conversely, i ...
Variations in magmatic processes along the East Greenland
... central Greenland in Late Cretaceous/Early Tertiary times (Fig. 1). Thus, the Tertiary volcanism of the North Atlantic margins prior to and during break-up is associated with mantle plume activity within a circle of radius of more than 1200 km. Systematic seismic investigations along the East Greenl ...
... central Greenland in Late Cretaceous/Early Tertiary times (Fig. 1). Thus, the Tertiary volcanism of the North Atlantic margins prior to and during break-up is associated with mantle plume activity within a circle of radius of more than 1200 km. Systematic seismic investigations along the East Greenl ...
The role of magmatically driven lithospheric thickening on arc front
... Ranges, Andean, Lesser Antilles, and Izu-Bonin-Mariana arcs. These examples demonstrate both the prevalence of arc front migration and the strong variability in migration that reflects regional history. Data for the Peninsular Ranges Batholith in Southern California were obtained from Kistler et al. ...
... Ranges, Andean, Lesser Antilles, and Izu-Bonin-Mariana arcs. These examples demonstrate both the prevalence of arc front migration and the strong variability in migration that reflects regional history. Data for the Peninsular Ranges Batholith in Southern California were obtained from Kistler et al. ...
PDF (Chapter 11. Evolution of the Mantle)
... (BABB) are closer to MORB in composition and, if the depth of the low-velocity zone and the depths of earthquakes can be used as a guide, tap a source deeper than 150 km. Many BABBs are intermediate in chemistry to MORB and OIB. This and other evidence indicates that the enriched reservoir is shallo ...
... (BABB) are closer to MORB in composition and, if the depth of the low-velocity zone and the depths of earthquakes can be used as a guide, tap a source deeper than 150 km. Many BABBs are intermediate in chemistry to MORB and OIB. This and other evidence indicates that the enriched reservoir is shallo ...
The Moho in subduction zones - Earth and Space Sciences at the
... nature of subduction zones implies the convergence of two plates, each characterized by a distinct Moho: one Moho associated with the incoming oceanic plate and another that may be of either continental or oceanic affinity. In this paper, we shall examine the processes operating in subduction zone fo ...
... nature of subduction zones implies the convergence of two plates, each characterized by a distinct Moho: one Moho associated with the incoming oceanic plate and another that may be of either continental or oceanic affinity. In this paper, we shall examine the processes operating in subduction zone fo ...
Continent formation through time
... through mag- matic addition, with the long-term rates of magma production being similar to that in island arcs (Clift et al. 2009; DeCelles et al. 2009). Magma pro- duction is increased in continental arcs during high- flux periods (‘flareups’), although the rate of new continental growth may not be ...
... through mag- matic addition, with the long-term rates of magma production being similar to that in island arcs (Clift et al. 2009; DeCelles et al. 2009). Magma pro- duction is increased in continental arcs during high- flux periods (‘flareups’), although the rate of new continental growth may not be ...
Plate Tectonics
... The movement of plates on Earth causes forces that build up energy in rocks. The release of this energy can produce vibrations in Earth that you know as earthquakes. Earthquakes occur every day. Many of them are too small to be felt by humans, but each event tells scientists something more about the ...
... The movement of plates on Earth causes forces that build up energy in rocks. The release of this energy can produce vibrations in Earth that you know as earthquakes. Earthquakes occur every day. Many of them are too small to be felt by humans, but each event tells scientists something more about the ...
Convergence of tectonic reconstructions and mantle - HAL-Insu
... The evolution of the area-age distribution of the seafloor through time is ...
... The evolution of the area-age distribution of the seafloor through time is ...
Glossary Accommodation zone—Accommodation zone is the zone
... structures (Christie-Blick & Biddle 1985). This stage ends at different times at different locations along the transform. The end takes place when the continental plate segment becomes juxtaposed with oceanic plate undergoing active accretion. Active continental-oceanic stage of the transform margin ...
... structures (Christie-Blick & Biddle 1985). This stage ends at different times at different locations along the transform. The end takes place when the continental plate segment becomes juxtaposed with oceanic plate undergoing active accretion. Active continental-oceanic stage of the transform margin ...
Slab behaviour and its surface expression: new insights
... mandatory. By considering the tectonic evolution of a region, gravity modelling can be used to test different evolution models. This has the additional advantage that the density distribution at depth is explained by the tectonic evolution. No ‘‘mysterious’’ bodies with density contrasts that best f ...
... mandatory. By considering the tectonic evolution of a region, gravity modelling can be used to test different evolution models. This has the additional advantage that the density distribution at depth is explained by the tectonic evolution. No ‘‘mysterious’’ bodies with density contrasts that best f ...
`Azores Hotspot`a Wetspot?
... Carbon and water were analyzed first in double face polished melt/glass inclusions by Fourier transform infrared spectroscopy. We used a Nicolet Magna-IR 550 spectrometer, equipped with a Globar source, an MCT/A detector cooled with N2, and a X-KBr beam splitter, which is coupled with a Spectra-Tech ...
... Carbon and water were analyzed first in double face polished melt/glass inclusions by Fourier transform infrared spectroscopy. We used a Nicolet Magna-IR 550 spectrometer, equipped with a Globar source, an MCT/A detector cooled with N2, and a X-KBr beam splitter, which is coupled with a Spectra-Tech ...
- White Rose Research Online
... occur within the upper 25 km of the crust, and no sub–crustal earthquakes occur anywhere in the region. These crustal thickness estimates suggest that there is very little underthrusting of the Arabian plate beneath eastern Turkey. Sandvol et al. (2003b) correlate large shear–wave splitting delay ti ...
... occur within the upper 25 km of the crust, and no sub–crustal earthquakes occur anywhere in the region. These crustal thickness estimates suggest that there is very little underthrusting of the Arabian plate beneath eastern Turkey. Sandvol et al. (2003b) correlate large shear–wave splitting delay ti ...
On the role of subducting oceanic plateaus in the development of
... (Kirby et al., 1996a), slabs would lose their compositional buoyancy at this shallow depth, regardless of their crustal thickness. Only a kinetically hindered reaction from basalt to eclogite would cause the slab to preserve (some of) its compositional buoyancy to greater depth. Therefore, the hypot ...
... (Kirby et al., 1996a), slabs would lose their compositional buoyancy at this shallow depth, regardless of their crustal thickness. Only a kinetically hindered reaction from basalt to eclogite would cause the slab to preserve (some of) its compositional buoyancy to greater depth. Therefore, the hypot ...
Niu, Y., Generation and evolution of basaltic magmas
... felsic (i.e., higher SiO2) or less mafic (i.e., lower FeO and MgO, and lower MgO/FeO ratio) than the source rock. In other words, basaltic melts result from partial melting of mantle peridotites; partial melting of basaltic rocks (basalts, diabases, gabbros etc.) cannot produce basaltic melts, but m ...
... felsic (i.e., higher SiO2) or less mafic (i.e., lower FeO and MgO, and lower MgO/FeO ratio) than the source rock. In other words, basaltic melts result from partial melting of mantle peridotites; partial melting of basaltic rocks (basalts, diabases, gabbros etc.) cannot produce basaltic melts, but m ...
Hotspots, mantle plumes and core heat loss
... their way to the top boundary. The fact that the average depth cold plume reach is not exactly the maximum depth comes from the fact that there is always one on its way to the bottom boundary. Many hot plumes start because there is a local minimum in the average temperature pro¢le just outside the b ...
... their way to the top boundary. The fact that the average depth cold plume reach is not exactly the maximum depth comes from the fact that there is always one on its way to the bottom boundary. Many hot plumes start because there is a local minimum in the average temperature pro¢le just outside the b ...
S-Velocity Structure of the Upper Mantle
... Knowledge of the velocity structure of the crust and upper mantle can improve source studies and aid investigations into mantle dynamics. Using an initial data set of single-station phase measurements of surface waves recorded on the USArray Transportable Array, we investigate the phase-velocity str ...
... Knowledge of the velocity structure of the crust and upper mantle can improve source studies and aid investigations into mantle dynamics. Using an initial data set of single-station phase measurements of surface waves recorded on the USArray Transportable Array, we investigate the phase-velocity str ...
Introduction - Beck-Shop
... and evolution of Earth’s continental crust. First, by what process or processes has the continental crust been extracted from Earth’s mantle, how have these processes changed through time, and has extraction been a continuous or episodic activity? Second, how much of the continental crust has been r ...
... and evolution of Earth’s continental crust. First, by what process or processes has the continental crust been extracted from Earth’s mantle, how have these processes changed through time, and has extraction been a continuous or episodic activity? Second, how much of the continental crust has been r ...
Fulltext - ETH E
... for the Algero-Provençal and Tyrrhenian Basins, where a shallow asthenospheric layer is observed. The lithosphere-asthenosphere system of the western Mediterranean clearly differentiates itself from the structure of the older eastern Atlantic Ocean as well as from the structure of a young (4 to 20 ...
... for the Algero-Provençal and Tyrrhenian Basins, where a shallow asthenospheric layer is observed. The lithosphere-asthenosphere system of the western Mediterranean clearly differentiates itself from the structure of the older eastern Atlantic Ocean as well as from the structure of a young (4 to 20 ...
Plate generation and two-phase damage theory in a model of
... to add another level of sophistication to previous work, but is still obviously a simplification of fully variable viscosity convection and hence convection in Earth. Our goal though is to ascertain the general plate behaviours (i.e. narrow boundary zones separated by rigid plate interiors) of two-p ...
... to add another level of sophistication to previous work, but is still obviously a simplification of fully variable viscosity convection and hence convection in Earth. Our goal though is to ascertain the general plate behaviours (i.e. narrow boundary zones separated by rigid plate interiors) of two-p ...
GUIDE TO PLATE TECTONICS AND EARTHQUAKES
... plate boundaries explain global-scale patterns of earthquakes and volcanoes. The Plate Tectonic PowerPoint Presentation is an introduction to plate tectonics with links to teaching resources tailored for a middle school audience. We recommend that first-time users download and view this presentation ...
... plate boundaries explain global-scale patterns of earthquakes and volcanoes. The Plate Tectonic PowerPoint Presentation is an introduction to plate tectonics with links to teaching resources tailored for a middle school audience. We recommend that first-time users download and view this presentation ...
Do fracture zones define continental margin segmentation
... long-lived first- and second-order offsets in the Mid-Atlantic Ridge (MAR) which can be traced to each margin as fracture zones or fracture-zone-like features. The relatively narrow width of these zones suggests that the transition from rift- to transform-style structures is similarly abrupt. However ...
... long-lived first- and second-order offsets in the Mid-Atlantic Ridge (MAR) which can be traced to each margin as fracture zones or fracture-zone-like features. The relatively narrow width of these zones suggests that the transition from rift- to transform-style structures is similarly abrupt. However ...
Post-glacial rebound
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Post-glacial rebound (sometimes called continental rebound) is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. Post-glacial rebound and isostatic depression are different parts of a process known as either glacial isostasy, glacial isostatic adjustment, or glacioisostasy. Glacioisostasy is the solid Earth deformation associated with changes in ice mass distribution. The most obvious and direct affects of post-glacial rebound are readily apparent in northern Europe (especially Scotland, Estonia, Latvia, Fennoscandia, and northern Denmark), Siberia, Canada, the Great Lakes of Canada and the United States, the coastal region of the US state of Maine, parts of Patagonia, and Antarctica. However, through processes known as ocean siphoning and continental levering, the effects of post-glacial rebound on sea-level are felt globally far from the locations of current and former ice sheets.