DEEP STRUCTURE AND GEOPHYSICAL PROCESSES BENEATH
... The purpose of this chapter is to use improved numerical calculations similar to those used by Toksoz et al. (1971) to test the effect of various physical parameters on the evolution of the slab. ...
... The purpose of this chapter is to use improved numerical calculations similar to those used by Toksoz et al. (1971) to test the effect of various physical parameters on the evolution of the slab. ...
Science Article PDF - Geological Society of America
... more we learn about its structure and morphology, the more difficult it is to postulate a simple model to explain its tectonic evolution. Subduction has occurred along the southern South America–Antarctic Peninsula margin for most of the past 200 m.y. (Tanner et al., 1982, Barker and Dalziel, 1983; ...
... more we learn about its structure and morphology, the more difficult it is to postulate a simple model to explain its tectonic evolution. Subduction has occurred along the southern South America–Antarctic Peninsula margin for most of the past 200 m.y. (Tanner et al., 1982, Barker and Dalziel, 1983; ...
Pb composition of Mesozoic Pacific oceanic crust
... Concerning Site 1149 (Abrams, personal communication) the thickness of the cherts decreases while the thickness of the clays increases in northward. The total thickness of the subducted sediment, however, stays more or less constant. Strong links between the lithology and geochemistry exist for most ...
... Concerning Site 1149 (Abrams, personal communication) the thickness of the cherts decreases while the thickness of the clays increases in northward. The total thickness of the subducted sediment, however, stays more or less constant. Strong links between the lithology and geochemistry exist for most ...
IODP Expedition 340T: Borehole Logging at Atlantis Massif Oceanic
... the base of this olivine-rich troctolite zone are more relevant in controlling seismic properties than alteration within the zone itself. Nevertheless, there is a distinct drop of over 0.5 km s -1 at 310 mbsf, the top of the zone, and an increase of ~1 km s -1 below the base. The seismic velocity of ...
... the base of this olivine-rich troctolite zone are more relevant in controlling seismic properties than alteration within the zone itself. Nevertheless, there is a distinct drop of over 0.5 km s -1 at 310 mbsf, the top of the zone, and an increase of ~1 km s -1 below the base. The seismic velocity of ...
- 2.8 Mo - UFR Sciences et techniques
... and (2) available computer resources must afford the vast computational cost of fully numerical global-scale simulation. Fortunately, in the last 10 yr, the field of numerical modelling of global-scale seismic wave propagation in 3-D anisotropic structures has made significant progress due to the in ...
... and (2) available computer resources must afford the vast computational cost of fully numerical global-scale simulation. Fortunately, in the last 10 yr, the field of numerical modelling of global-scale seismic wave propagation in 3-D anisotropic structures has made significant progress due to the in ...
Constraints on the composition of the Aleutian arc lower crust from
... There is a sharp step in velocity at the top of the lower crust (~0.4 km/s), and along-arc variations in lower crustal velocity appear to correlate to variations in lava composition [Shillington et al., 2004]. These characteristics were attributed to mafic/ultramafic cumulates and/or garnet granulites ...
... There is a sharp step in velocity at the top of the lower crust (~0.4 km/s), and along-arc variations in lower crustal velocity appear to correlate to variations in lava composition [Shillington et al., 2004]. These characteristics were attributed to mafic/ultramafic cumulates and/or garnet granulites ...
Lateral Density Inhomogeneities of the Continental and Oceanic
... averaged character of the data used [1]. Only in active convergent zones, island arcs, and deep trenches have notable anomalies related to the isostatic disequilib rium of these structures been noted. Therefore, all the data beyond these structures will be further considered as isostatically compen ...
... averaged character of the data used [1]. Only in active convergent zones, island arcs, and deep trenches have notable anomalies related to the isostatic disequilib rium of these structures been noted. Therefore, all the data beyond these structures will be further considered as isostatically compen ...
Seismic velocity structure of the rifted margin of the eastern Grand
... of the Grand Banks of Newfoundland, Canada. This velocity model was obtained by a tomographic inversion of wide-angle data recorded on a linear array of 24 ocean bottom seismometers (OBSs). At the landward side, we imaged a crustal thickness of 27 km in Flemish Pass and beneath Beothuk Knoll, which ...
... of the Grand Banks of Newfoundland, Canada. This velocity model was obtained by a tomographic inversion of wide-angle data recorded on a linear array of 24 ocean bottom seismometers (OBSs). At the landward side, we imaged a crustal thickness of 27 km in Flemish Pass and beneath Beothuk Knoll, which ...
Mechanical (de-)coupling of the lithosphere in the Valencia Trough
... [14], the low seismic velocities found [15] and the bending of faults that £atten out at the top of this level, have been usually pointed as indicators of such a low-viscosity zone [16]. Additionally, some authors argue that the semi-horizontal, lower crustal strong seismic re£ectors observed in man ...
... [14], the low seismic velocities found [15] and the bending of faults that £atten out at the top of this level, have been usually pointed as indicators of such a low-viscosity zone [16]. Additionally, some authors argue that the semi-horizontal, lower crustal strong seismic re£ectors observed in man ...
On origin of near-axis volcanism and faulting at fast spreading mid
... slow spreading mid-ocean ridges, where they accommodate up to 10^20% of extension associated with plate spreading [18,19]. Outward-dipping normal faults are, however, almost unique to fast and intermediate spreading ridges. Establishing their origin is essential for understanding the formation of th ...
... slow spreading mid-ocean ridges, where they accommodate up to 10^20% of extension associated with plate spreading [18,19]. Outward-dipping normal faults are, however, almost unique to fast and intermediate spreading ridges. Establishing their origin is essential for understanding the formation of th ...
Seismic velocity structure and anisotropy of the Alaska subduction
... et al., 2011]. This wedge of overthickened crust, presumably an oceanic plateau [Christeson et al., 2010], is considered to be responsible for the uplift of the Alaska Range, the rapid uplift and remarkable relief of the coastal Saint Elias mountains, the propagation of intraplate deformation severa ...
... et al., 2011]. This wedge of overthickened crust, presumably an oceanic plateau [Christeson et al., 2010], is considered to be responsible for the uplift of the Alaska Range, the rapid uplift and remarkable relief of the coastal Saint Elias mountains, the propagation of intraplate deformation severa ...
A rare great earthquake on an oceanic fossil
... the Macquarie Basin and its crust was formed by spreading on the Macquarie Spreading Ridge. Spreading initiated on the Macquarie Ridge around 42 Ma and the ridge was an active spreading centre until around 29 Ma. From that point, the instantaneous pole of rotation of the Australian Plate gradually m ...
... the Macquarie Basin and its crust was formed by spreading on the Macquarie Spreading Ridge. Spreading initiated on the Macquarie Ridge around 42 Ma and the ridge was an active spreading centre until around 29 Ma. From that point, the instantaneous pole of rotation of the Australian Plate gradually m ...
Mountain Building Web Activity
... The Caucasus Mountains are located between the Black Sea and Caspian Sea, separating Europe from Asia. This 550-mile long mountain range lies between Russia to the north and the countries of Georgia, Azerbajian and Armenia to the south. With an average elevation of 6000-9000 feet (~1800-2700 meters) ...
... The Caucasus Mountains are located between the Black Sea and Caspian Sea, separating Europe from Asia. This 550-mile long mountain range lies between Russia to the north and the countries of Georgia, Azerbajian and Armenia to the south. With an average elevation of 6000-9000 feet (~1800-2700 meters) ...
Crustal motion in the Southern Andes (26°–36°S): Do the Andes
... plate convergence provides the kinematic framework for nearly complete explanation of the observed velocity field. The results suggest the oceanic Nazca boundary is fully locked while the continental backarc boundary creeps continuously at 4.5 mm/yr. The excellent fit of model to data (1.7 mm/yr RM ...
... plate convergence provides the kinematic framework for nearly complete explanation of the observed velocity field. The results suggest the oceanic Nazca boundary is fully locked while the continental backarc boundary creeps continuously at 4.5 mm/yr. The excellent fit of model to data (1.7 mm/yr RM ...
The Dynamic Earth - Betavak-NLT
... on an important consequence of the dynamic Earth: earthquakes. The first three chapters combine to form the basis of this course. You will have completed the course only when you have finished these chapters and one of the optional chapters (Chapter 4, 5 or 6). The other optional chapters can be use ...
... on an important consequence of the dynamic Earth: earthquakes. The first three chapters combine to form the basis of this course. You will have completed the course only when you have finished these chapters and one of the optional chapters (Chapter 4, 5 or 6). The other optional chapters can be use ...
A Global View of the Lithosphere-Asthenosphere
... used as chiral initiators of asymmetric autocatalysis. When (S)-3 was used as the chiral trigger, enantioselective addition of i-Pr2Zn to pyrimidine5-carbaldehyde 4 afforded (S)-pyrimidyl alkanol 5 with 95% ee in 96% yield (entry 25). In contrast, the reaction in the presence of (R)-3 gave (R)-alkan ...
... used as chiral initiators of asymmetric autocatalysis. When (S)-3 was used as the chiral trigger, enantioselective addition of i-Pr2Zn to pyrimidine5-carbaldehyde 4 afforded (S)-pyrimidyl alkanol 5 with 95% ee in 96% yield (entry 25). In contrast, the reaction in the presence of (R)-3 gave (R)-alkan ...
Geology First active hydrothermal vents on an ultraslow-spreading center: Southwest Indian Ridge
... Our study has revealed the first direct evidence for active venting on the SWIR, providing strong support for the hypothesis that high-temperature hydrothermal circulation is widespread along all ultraslow-spreading ridges (German et al., 1998; Baker et al., 2004), at least in the magmatically robus ...
... Our study has revealed the first direct evidence for active venting on the SWIR, providing strong support for the hypothesis that high-temperature hydrothermal circulation is widespread along all ultraslow-spreading ridges (German et al., 1998; Baker et al., 2004), at least in the magmatically robus ...
This document in RTF format
... The airgun lines that we propose are designed to provide sources of compressional waves that criss-cross a roughly 100x100 km region surrounding axial volcano. Ray coverage within the central 40x40 km part of this region will be particularly good, and suitable for 3D imaging (figure 3). We expect to ...
... The airgun lines that we propose are designed to provide sources of compressional waves that criss-cross a roughly 100x100 km region surrounding axial volcano. Ray coverage within the central 40x40 km part of this region will be particularly good, and suitable for 3D imaging (figure 3). We expect to ...
to the PDF file. - CURVE
... The Fish Creek Mountains, located in north-central Nevada, is a site o f multiple igneous events ranging from 35Ma to IMa, covering most of the igneous history o f the Great Basin where my goal of this project is to investigate the Paleogene volcanism within the FCM. Samples collected from the FCM a ...
... The Fish Creek Mountains, located in north-central Nevada, is a site o f multiple igneous events ranging from 35Ma to IMa, covering most of the igneous history o f the Great Basin where my goal of this project is to investigate the Paleogene volcanism within the FCM. Samples collected from the FCM a ...
Nature of Earthquakes
... the propagation of earthquake waves, the mantle between the core and crust is divided into the lower mantle, transition zone, and upper mantle (Figure1). As a result of increase in pressure, the seismic velocity and density increase with depth in the lower mantle. The increase in the amount of iron ...
... the propagation of earthquake waves, the mantle between the core and crust is divided into the lower mantle, transition zone, and upper mantle (Figure1). As a result of increase in pressure, the seismic velocity and density increase with depth in the lower mantle. The increase in the amount of iron ...
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.