PDF 51 - The Open University
... 1920-1960 A range of geophysical arguments was used to contest Wegener's theory. Most importantly, the lack of a mechanism strong enough to 'drive continents across the ocean basins' seriously undermined the credibility of his ideas. The theory of continental drift remained a highly controversial id ...
... 1920-1960 A range of geophysical arguments was used to contest Wegener's theory. Most importantly, the lack of a mechanism strong enough to 'drive continents across the ocean basins' seriously undermined the credibility of his ideas. The theory of continental drift remained a highly controversial id ...
Geochemical anomalies throughout the 2009 Aquila - Earth
... the main shock, remaining anomalous in the following months, but with lower values. Furthermore, just in correspondence of this lineament highest values of radon (up to 40.000 Bq/m3) were found. The transects perpendicular to the Paganica Fault clearly highlighted the role of the main fracture at su ...
... the main shock, remaining anomalous in the following months, but with lower values. Furthermore, just in correspondence of this lineament highest values of radon (up to 40.000 Bq/m3) were found. The transects perpendicular to the Paganica Fault clearly highlighted the role of the main fracture at su ...
Geochemistry, Geophysics, Geosystems
... in regions where the crust is divided in three layers, and two crustal rheologies in regions where the crystalline crust consists of two layers. The rheology of diabase is assigned to the Gulf of Mexico with one crystalline crust layer of an oceanic type (Table 1). We do not specify any rheology for ...
... in regions where the crust is divided in three layers, and two crustal rheologies in regions where the crystalline crust consists of two layers. The rheology of diabase is assigned to the Gulf of Mexico with one crystalline crust layer of an oceanic type (Table 1). We do not specify any rheology for ...
︎PDF - Fabio Crameri
... and Kaus, 2012], or pore fluid pressure [Dymkova and Gerya, 2013]. The addition of water or melt into the lithosphere also has a weakening effect [Hirth and Kohlstedt, 2003]. Once subduction has been initiated, a lithosphere-scale weak channel maintained by such a mechanism and/or by actual weak sed ...
... and Kaus, 2012], or pore fluid pressure [Dymkova and Gerya, 2013]. The addition of water or melt into the lithosphere also has a weakening effect [Hirth and Kohlstedt, 2003]. Once subduction has been initiated, a lithosphere-scale weak channel maintained by such a mechanism and/or by actual weak sed ...
Oil+Gas_104nd Edition_January 2016
... to a certain degree) is strikingly different from that of magma-poor or volcanic rifted margin. The seismic interpretation has identified rifted margins as large scale tilted fault blocks are not always clearly four major crustal types or domains that make up the margin: imaged. Instead, wide expans ...
... to a certain degree) is strikingly different from that of magma-poor or volcanic rifted margin. The seismic interpretation has identified rifted margins as large scale tilted fault blocks are not always clearly four major crustal types or domains that make up the margin: imaged. Instead, wide expans ...
3 Gravity and the lithosphere
... It has long been recognized that the surface elevation of the continents is in some way related to the density distribution in the subsurface. The gravity field at the surface of the earth reflects the distribution of mass at depth and gravity measurements across mountain belts show that regions of ...
... It has long been recognized that the surface elevation of the continents is in some way related to the density distribution in the subsurface. The gravity field at the surface of the earth reflects the distribution of mass at depth and gravity measurements across mountain belts show that regions of ...
EarthComm_c2s6_185-197
... from radioactive decay in Earth would work against the cooling and contraction process. According to Wegener, there was a huge supercontinent called Pangea. (Pangea is Greek for “all land.”) About 200 million years ago, it broke into separate continents. The continents then moved apart. Wegener clai ...
... from radioactive decay in Earth would work against the cooling and contraction process. According to Wegener, there was a huge supercontinent called Pangea. (Pangea is Greek for “all land.”) About 200 million years ago, it broke into separate continents. The continents then moved apart. Wegener clai ...
Earthquake size distribution in subduction zones
... Earthquake size distribution in subduction zones linked to slab buoyancy Tomoaki Nishikawa* and Satoshi Ide The occurrence of subduction zone earthquakes is primarily controlled by the state of stress on the interface between the subducting and overriding plates. This stress state is influenced by t ...
... Earthquake size distribution in subduction zones linked to slab buoyancy Tomoaki Nishikawa* and Satoshi Ide The occurrence of subduction zone earthquakes is primarily controlled by the state of stress on the interface between the subducting and overriding plates. This stress state is influenced by t ...
︎PDF - Fabio Crameri
... Subduction zones are one of the most prominent features on a planet that undergoes plate tectonics, not only in terms of surface morphology but also in terms of the planet’s dynamic evolution. Its importance for the dynamics is highlighted by the fact that the sinking portions of a plate (i.e., slab ...
... Subduction zones are one of the most prominent features on a planet that undergoes plate tectonics, not only in terms of surface morphology but also in terms of the planet’s dynamic evolution. Its importance for the dynamics is highlighted by the fact that the sinking portions of a plate (i.e., slab ...
Mantle Exhumation in an Early Paleozoic Passive Margin, Northern
... well-developed plagioclase coronae on spinel and records cooling from ∼1000⬚ to 600⬚C and decompression across the spinel-plagioclase peridotite facies boundary at ∼0.7 GPa. The troctolite boudins record cooling to 850⬚C through the same facies reaction at ∼0.8 GPa. In an aureole surrounding the per ...
... well-developed plagioclase coronae on spinel and records cooling from ∼1000⬚ to 600⬚C and decompression across the spinel-plagioclase peridotite facies boundary at ∼0.7 GPa. The troctolite boudins record cooling to 850⬚C through the same facies reaction at ∼0.8 GPa. In an aureole surrounding the per ...
Some remarks about the degree-one deformation of the Earth
... Degree-one deformation involving a translation of the external surface may have some geodetic consequences. I n fact, observation stations, being located on the external surface, undergo the surface translation. If these stations are used t o define il reference frame, the centre of this frame will ...
... Degree-one deformation involving a translation of the external surface may have some geodetic consequences. I n fact, observation stations, being located on the external surface, undergo the surface translation. If these stations are used t o define il reference frame, the centre of this frame will ...
VS and density structure beneath the Colorado Plateau constrained
... Received 12 May 2011; revised 22 December 2011; accepted 28 December 2011; published 25 February 2012. ...
... Received 12 May 2011; revised 22 December 2011; accepted 28 December 2011; published 25 February 2012. ...
The anatomy and ontogeny of modern intra
... subducted plate reaches magmagenetic depths (100 –150 km) and causes the mantle to melt. This configuration must exist for long enough that melts generated in the overlying asthenospheric wedge not only reach the surface but also persist until a stable magmatic conduit system is established. When th ...
... subducted plate reaches magmagenetic depths (100 –150 km) and causes the mantle to melt. This configuration must exist for long enough that melts generated in the overlying asthenospheric wedge not only reach the surface but also persist until a stable magmatic conduit system is established. When th ...
2.01 Cosmochemical Estimates of Mantle Composition
... is little evidence for compositional gradients within the inner solar system as represented by the terrestrial planets and the asteroids. There are no systematic variations with distance from the Sun, either in the chemistry of the inner planets, Mercury, Venus, Earth, Moon, Mars, and including the ...
... is little evidence for compositional gradients within the inner solar system as represented by the terrestrial planets and the asteroids. There are no systematic variations with distance from the Sun, either in the chemistry of the inner planets, Mercury, Venus, Earth, Moon, Mars, and including the ...
38. EVIDENCE FOR DETACHMENT TECTONICS ON THE IBERIA
... capped by a 450- to 750-m-thick seismically transparent layer of prerift or pretilting sediment (Fig. 9). The basement itself exhibits velocities of 5.5 to 6 km/s, whereas within the pretilting layer the velocity values between 2.8 and 3.4 km/s are relatively low compared to approximately 4.1 km/s c ...
... capped by a 450- to 750-m-thick seismically transparent layer of prerift or pretilting sediment (Fig. 9). The basement itself exhibits velocities of 5.5 to 6 km/s, whereas within the pretilting layer the velocity values between 2.8 and 3.4 km/s are relatively low compared to approximately 4.1 km/s c ...
Long-term continental areal reduction produced by tectonic processes
... either through back-arc extension or plate-creation, approximately 94% is eventually destroyed through areal removal at subduction zones. The remaining 6% is taken up through deformation of continental crust. We found the total area produced at oceanic ridges and extending back-arc basins to be appr ...
... either through back-arc extension or plate-creation, approximately 94% is eventually destroyed through areal removal at subduction zones. The remaining 6% is taken up through deformation of continental crust. We found the total area produced at oceanic ridges and extending back-arc basins to be appr ...
The evolving nature of terrestrial crust from the Hadean, through the
... to the long-lived, relatively slowly maturing, thick cratonic nuclei found today in several Precambrian shields. The second type of Archaean continental lithosphere formed much more rapidly, over periods of 150–300 Ma, at several times during the Archaean. Magmas were initially erupted as stacks of ...
... to the long-lived, relatively slowly maturing, thick cratonic nuclei found today in several Precambrian shields. The second type of Archaean continental lithosphere formed much more rapidly, over periods of 150–300 Ma, at several times during the Archaean. Magmas were initially erupted as stacks of ...
Crustal thickness of V-shaped ridges south of the Azores: -39
... depends primarily on the flux of the plume (mainly a function of the temperature anomaly and diameter of the plume), viscosity structure of the mantle, spreading rate of nearby mid-ocean ridges, and relative motion of the ridge with respect to the plume. In the case of the northern MAR, the mantle t ...
... depends primarily on the flux of the plume (mainly a function of the temperature anomaly and diameter of the plume), viscosity structure of the mantle, spreading rate of nearby mid-ocean ridges, and relative motion of the ridge with respect to the plume. In the case of the northern MAR, the mantle t ...
EARTHQUAKES
... material it travels through. Because of the behavior of these different waves, scientists have indirect evidence for the solid inner core and liquid outer core of Earth; because earthquake waves travel faster through the mantle than through the crust, scientists know that the mantle is denser than t ...
... material it travels through. Because of the behavior of these different waves, scientists have indirect evidence for the solid inner core and liquid outer core of Earth; because earthquake waves travel faster through the mantle than through the crust, scientists know that the mantle is denser than t ...
A relatively reduced Hadean continental crust and - HAL
... To ensure the calculation and comparison of fO2 between different periods, the following criteria were applied: (1) the well-studied Hadean Jack Hills and Hadean to Archean Wyoming Province detrital zircons and post-Hadean inherited zircons, typical of continental crust origin, were selected; (2) th ...
... To ensure the calculation and comparison of fO2 between different periods, the following criteria were applied: (1) the well-studied Hadean Jack Hills and Hadean to Archean Wyoming Province detrital zircons and post-Hadean inherited zircons, typical of continental crust origin, were selected; (2) th ...
Generation of plate tectonics from mantle convection
... spreading (Hess, 1962; Vine and Matthews, 1963), there remains little doubt that the direct energy source for plate tectonics and all its attendant features (mountain building, earthquakes, volcanoes, etc.) is the release of the mantle’s gravitational potential energy through convective overturn (su ...
... spreading (Hess, 1962; Vine and Matthews, 1963), there remains little doubt that the direct energy source for plate tectonics and all its attendant features (mountain building, earthquakes, volcanoes, etc.) is the release of the mantle’s gravitational potential energy through convective overturn (su ...
Igneous Geology - Illinois Wesleyan University
... •Partial crystallization and partial melting are important. As crystals form from a melt, the melt becomes depleted in elements that are incorporated in those minerals and enriched in elements that are not incorporated into those minerals. If the crystals are removed from contact with the melt (by s ...
... •Partial crystallization and partial melting are important. As crystals form from a melt, the melt becomes depleted in elements that are incorporated in those minerals and enriched in elements that are not incorporated into those minerals. If the crystals are removed from contact with the melt (by s ...
The lithosphere and asthenosphere of the
... asthenosphere on which they float. Being situated on the Mid-Atlantic Ridge, Iceland provides a unique opportunity to study the interaction between a plume and such an overriding oceanic ridge. Admittedly, identifying the seismic anomaly beneath Iceland (Wolfe et al. 1997) with a plume has recently ...
... asthenosphere on which they float. Being situated on the Mid-Atlantic Ridge, Iceland provides a unique opportunity to study the interaction between a plume and such an overriding oceanic ridge. Admittedly, identifying the seismic anomaly beneath Iceland (Wolfe et al. 1997) with a plume has recently ...
The lithosphere and asthenosphere of the Iceland hotspot from
... asthenosphere on which they float. Being situated on the Mid-Atlantic Ridge, Iceland provides a unique opportunity to study the interaction between a plume and such an overriding oceanic ridge. Admittedly, identifying the seismic anomaly beneath Iceland (Wolfe et al. 1997) with a plume has recently ...
... asthenosphere on which they float. Being situated on the Mid-Atlantic Ridge, Iceland provides a unique opportunity to study the interaction between a plume and such an overriding oceanic ridge. Admittedly, identifying the seismic anomaly beneath Iceland (Wolfe et al. 1997) with a plume has recently ...
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.