11. GEODYNAMIC EVOLUTION OF THE CÔTE D`IVOIRE
... crusts. During Late Cretaceous times, the transform margin experienced continuous subsidence leading to the progressive upslope migration of the reef. An increasing subsidence rate characterized the early Coniacian, close to the time when the first continent/ocean transform transition occurred. No s ...
... crusts. During Late Cretaceous times, the transform margin experienced continuous subsidence leading to the progressive upslope migration of the reef. An increasing subsidence rate characterized the early Coniacian, close to the time when the first continent/ocean transform transition occurred. No s ...
A cool model for the Iceland hot spot
... A holistic appraisal of the evidence available from the Iceland melt anomaly suggests that, if the assumption of a plume is dropped, an upper-mantle, moderate-temperature model is natural, reasonable and not without support. The primary observations that require explanation are the local production ...
... A holistic appraisal of the evidence available from the Iceland melt anomaly suggests that, if the assumption of a plume is dropped, an upper-mantle, moderate-temperature model is natural, reasonable and not without support. The primary observations that require explanation are the local production ...
Subduction zones: observations and
... the cold, negatively-buoyant slabs provide the dominant force that drives plate motions, historically referred to as ‘slab-pull’ after Forsyth and Uyeda (1975). The terms plate, lithosphere, and thermal boundary layer are often used synonymously when describing convection calculations with dynamic p ...
... the cold, negatively-buoyant slabs provide the dominant force that drives plate motions, historically referred to as ‘slab-pull’ after Forsyth and Uyeda (1975). The terms plate, lithosphere, and thermal boundary layer are often used synonymously when describing convection calculations with dynamic p ...
Magmatic and tectonic evolution of the North Atlantic Journal of the
... unpublished). Between the two OBS profiles along the eastern side of the Jan Mayen Ridge the continent–ocean boundary is also marked by a steep gradient in the bathymetry, Bouguer map and free-air gravity map. Its imprint in the magnetic data is not clear because of poor data coverage, but the inter ...
... unpublished). Between the two OBS profiles along the eastern side of the Jan Mayen Ridge the continent–ocean boundary is also marked by a steep gradient in the bathymetry, Bouguer map and free-air gravity map. Its imprint in the magnetic data is not clear because of poor data coverage, but the inter ...
Strength of the lithosphere and strain localisation in the Baikal rift
... characteristic wavelengths in the Bouguer gravity signal. The Bouguer anomaly grid comes from gravity survey with original data spacing of about 1′ and includes terrain corrections (in a range of 200 km around each data station). This data set was originally produced by Russian Geodetic Service and ...
... characteristic wavelengths in the Bouguer gravity signal. The Bouguer anomaly grid comes from gravity survey with original data spacing of about 1′ and includes terrain corrections (in a range of 200 km around each data station). This data set was originally produced by Russian Geodetic Service and ...
The example of Piton de la Fournaise (Réun
... thereby, give quick solutions, but does not reflect the complexity of the volcano. By contrast, other authors (e.g. Gudmundsson, 2006) suggest that the layering may modify the state of stress in a volcano and thus the observed deformation. Using 2-D numerical models, it can be shown, for examples, t ...
... thereby, give quick solutions, but does not reflect the complexity of the volcano. By contrast, other authors (e.g. Gudmundsson, 2006) suggest that the layering may modify the state of stress in a volcano and thus the observed deformation. Using 2-D numerical models, it can be shown, for examples, t ...
15. Electrical Resistivity of Basalts from DSDP Leg 26
... Since the resistivity of hematite is much less than that of dry rocks (generally between 10~2 and 102 ohm-m, Keller, 1966), the presence of continuous or nearly continuous hematite plus electrolyte paths in these altered basalts appears to lead to their unexpectedly low resistivity. This mineralogic ...
... Since the resistivity of hematite is much less than that of dry rocks (generally between 10~2 and 102 ohm-m, Keller, 1966), the presence of continuous or nearly continuous hematite plus electrolyte paths in these altered basalts appears to lead to their unexpectedly low resistivity. This mineralogic ...
Viscosity of the asthenosphere from glacial isostatic adjustment and
... of asthenospheric thicknesses, provided that the asthenospheric viscosity is varied from 3 1018 Pa s for a thin (140 km) asthenosphere to 4 1019 Pa s for a thick (380 km) asthenosphere. Present-day vertical crustal motion predicted by the GIA models shows rates of a few tenths of a millimeter pe ...
... of asthenospheric thicknesses, provided that the asthenospheric viscosity is varied from 3 1018 Pa s for a thin (140 km) asthenosphere to 4 1019 Pa s for a thick (380 km) asthenosphere. Present-day vertical crustal motion predicted by the GIA models shows rates of a few tenths of a millimeter pe ...
Geodynpub_files/Taiwan, 1997
... compression. Compressive stresses reach the yield limit of the PSP in the arc area, which is a weak zone in the experiments. The plate fails at the western side of the arc along an eastward dipping fault, the Longitudinal Valley Fault. Underthrusting of the frontal wedge of the PSP along this fault ...
... compression. Compressive stresses reach the yield limit of the PSP in the arc area, which is a weak zone in the experiments. The plate fails at the western side of the arc along an eastward dipping fault, the Longitudinal Valley Fault. Underthrusting of the frontal wedge of the PSP along this fault ...
Ocean ridges - dynamicearth.de
... framework the western flank of the ridge is moving at more than twice the rate of the eastern flank (Fig. 6.8). It is also close to the South Pacific superswell (Section 12.8.3). Enhanced upwelling and hence flow in the asthenosphere from the superswell and viscous drag beneath the fast moving Pacif ...
... framework the western flank of the ridge is moving at more than twice the rate of the eastern flank (Fig. 6.8). It is also close to the South Pacific superswell (Section 12.8.3). Enhanced upwelling and hence flow in the asthenosphere from the superswell and viscous drag beneath the fast moving Pacif ...
Plate Tectonics: Evolution of the Ocean Floor
... as dense as the core. The upper mantle, known as the asthenosphere, is thought to consist of material that is very close to its melting point and “plastic,” so it is capable of flowing very slowly without fracturing. The best examples of such materials in everyday life are glass and glacial ice. Alt ...
... as dense as the core. The upper mantle, known as the asthenosphere, is thought to consist of material that is very close to its melting point and “plastic,” so it is capable of flowing very slowly without fracturing. The best examples of such materials in everyday life are glass and glacial ice. Alt ...
Beyond Plate Tectonics: “Plate” Dynamics
... it begins to accelerate. First it breaks free along diffuse high strain zones that progressively focus deformation. When stasis occurs as the result of surging taking place for over 10,000 years at the rate of 1m/yr, here is how the author believes the BSZ will be expressed. At the periphery of the ...
... it begins to accelerate. First it breaks free along diffuse high strain zones that progressively focus deformation. When stasis occurs as the result of surging taking place for over 10,000 years at the rate of 1m/yr, here is how the author believes the BSZ will be expressed. At the periphery of the ...
Imaging the lithosphere‐asthenosphere boundary
... 140° preprocessed to remove the instrument response. We restrict source depths to 0–75 km to minimize complications from depth phases. We rotate the horizontal components to obtain the transverse component, which we then Hilbert transform to remove the expected Hilbert transform of the SS phase and ...
... 140° preprocessed to remove the instrument response. We restrict source depths to 0–75 km to minimize complications from depth phases. We rotate the horizontal components to obtain the transverse component, which we then Hilbert transform to remove the expected Hilbert transform of the SS phase and ...
The Lithosphere – Asthenosphere System: Nature of the Tectonic
... 1998), but it fails to explain a large velocity reduction. Recently, I proposed that anelastic relaxation involving elastically-accommodated grain-boundary sliding might explain a sharp and large velocity drop at LAB (and MLD: mid-lithosphere discontinuity) (Karato, 2012). After a brief discussion ...
... 1998), but it fails to explain a large velocity reduction. Recently, I proposed that anelastic relaxation involving elastically-accommodated grain-boundary sliding might explain a sharp and large velocity drop at LAB (and MLD: mid-lithosphere discontinuity) (Karato, 2012). After a brief discussion ...
Powerpoint Presentation Physical Geology, 10/e
... Bay Area Earthquakes – Past and Future Pattern 3: northward progression of earthquakes • Earthquakes of 1865 and 1868 on the Hayward fault were preceded by five moderate earthquakes that moved northward up the Calaveras fault – Area of Hayward fault today is populated by 2 million people, with schoo ...
... Bay Area Earthquakes – Past and Future Pattern 3: northward progression of earthquakes • Earthquakes of 1865 and 1868 on the Hayward fault were preceded by five moderate earthquakes that moved northward up the Calaveras fault – Area of Hayward fault today is populated by 2 million people, with schoo ...
Upper mantle
... Lower mantle beneath cratons (Brazil; Africa) colder (higher P wave vel.) Pacific ocean; hotter- slower velocities Mid-Atlantic ridge: hot down to 400 km Dipping slabs beneath Japan and S. America visible at depth Lower mantle cold slaps also visible- favors single layer convection ...
... Lower mantle beneath cratons (Brazil; Africa) colder (higher P wave vel.) Pacific ocean; hotter- slower velocities Mid-Atlantic ridge: hot down to 400 km Dipping slabs beneath Japan and S. America visible at depth Lower mantle cold slaps also visible- favors single layer convection ...
Folds, Faults and Mountain Belts (Con`t.)
... Water greatly influences metamorphism. Aids in migration of unbonded atoms and ions. Allows for exchange of ions between adjacent grains. Water comes from a variety of sources Ground water Subducted oceanic crust Crystallization of magma Decomposition of water-rich minerals like amphiboles and clays ...
... Water greatly influences metamorphism. Aids in migration of unbonded atoms and ions. Allows for exchange of ions between adjacent grains. Water comes from a variety of sources Ground water Subducted oceanic crust Crystallization of magma Decomposition of water-rich minerals like amphiboles and clays ...
Tectonic erosion along the Japan and Peru convergent margins
... associated with the accretion of sediment from the subducting lower plate to the upper plate, whereas erosion of the upper plate has received much less attention. The difference in attention may result from the difficulty in resolving erosional structures in seismic records. Tectonic foreshortening ...
... associated with the accretion of sediment from the subducting lower plate to the upper plate, whereas erosion of the upper plate has received much less attention. The difference in attention may result from the difficulty in resolving erosional structures in seismic records. Tectonic foreshortening ...
Subduction zone evolution and deep slab structure
... Maghrebides and Carpathians subduction is going further “along the Alps-Betics retrobelt, where oceanic and thinned continental lithosphere occurred in the foreland to the east” (Carminati et al., 2004) and underneath the Adriatic and Mesomediterranean plate. The ApenninesMaghrebides and Carpathian ...
... Maghrebides and Carpathians subduction is going further “along the Alps-Betics retrobelt, where oceanic and thinned continental lithosphere occurred in the foreland to the east” (Carminati et al., 2004) and underneath the Adriatic and Mesomediterranean plate. The ApenninesMaghrebides and Carpathian ...
Mantle plumes persevere
... type of hotspot, that consider the motion of the mantle plumes themselves13. This in itself is exciting because seamount trails could potentially tell us about changes in mantle flow. The second hotspot type includes those that are sourced from shallower parts of the mantle. These hotspots are far m ...
... type of hotspot, that consider the motion of the mantle plumes themselves13. This in itself is exciting because seamount trails could potentially tell us about changes in mantle flow. The second hotspot type includes those that are sourced from shallower parts of the mantle. These hotspots are far m ...
On the origin of the asthenosphere
... presence of partial melting is assumed, it is necessary to invoke some mechanisms of melt accumulation in order to explain a large velocity reduction by partial melting. I will discuss this point later. 3.2. Mechanical properties Mechanical properties such as the seismic wave velocities and seismic ...
... presence of partial melting is assumed, it is necessary to invoke some mechanisms of melt accumulation in order to explain a large velocity reduction by partial melting. I will discuss this point later. 3.2. Mechanical properties Mechanical properties such as the seismic wave velocities and seismic ...
Formation of plate boundaries: The role of mantle volatilization
... mechanisms should include effects of volatiles like H2O and CO2 (e.g. Bercovici, 1998; Regenauer-Lieb et al., 2001; Solomatov, 2004; O'Neill et al., 2007). Their effects on the thermo-mechanical properties of the lithosphere have been considered in numerical simulations of the initiation of plate bo ...
... mechanisms should include effects of volatiles like H2O and CO2 (e.g. Bercovici, 1998; Regenauer-Lieb et al., 2001; Solomatov, 2004; O'Neill et al., 2007). Their effects on the thermo-mechanical properties of the lithosphere have been considered in numerical simulations of the initiation of plate bo ...
SEISMIC AND ASEISMIC SLIP ALONG SUBDUCTION ZONES AND
... among different island arcs; along some subduction zones the coupling is very strong, so that the plate motion is almost entirely taken up by seismic slip. It is relatively weak elsewhere and the seismic slip represents only a very minor part of the plate motion. Along some subduction zones, the bou ...
... among different island arcs; along some subduction zones the coupling is very strong, so that the plate motion is almost entirely taken up by seismic slip. It is relatively weak elsewhere and the seismic slip represents only a very minor part of the plate motion. Along some subduction zones, the bou ...
Numerical modeling
... structures related to slab propagation account for both penetration and non-penetration of the 660 km discontinuity. Non-penetration is favored by (i) low convergence rate, (ii) faster relative movement of the overriding plate, (iii) young age of the subducting slab and (iv) up-side-down turn-over o ...
... structures related to slab propagation account for both penetration and non-penetration of the 660 km discontinuity. Non-penetration is favored by (i) low convergence rate, (ii) faster relative movement of the overriding plate, (iii) young age of the subducting slab and (iv) up-side-down turn-over o ...