pdf file - University of Victoria
... My appreciation that there was a problem with the crustalthickening model for the Cordillera elevation came some 20 years ago from the Canadian Lithoprobe Program, an exceptionally successful multidisciplinary geoscience effort involving academia, Federal and Provincial geological surveys, and indus ...
... My appreciation that there was a problem with the crustalthickening model for the Cordillera elevation came some 20 years ago from the Canadian Lithoprobe Program, an exceptionally successful multidisciplinary geoscience effort involving academia, Federal and Provincial geological surveys, and indus ...
Introduction to Earth Science
... natural world as individual groups or categories rather than as a whole? Diff: 3 Topic: 1.6 Earth's Spheres Bloom's: Evaluating and Analyzing ...
... natural world as individual groups or categories rather than as a whole? Diff: 3 Topic: 1.6 Earth's Spheres Bloom's: Evaluating and Analyzing ...
2-D georesistivity structure in the central part of the northeastern...
... The apparent resistivity profile at Site 902 turned out to be very similar to those at Sites 304 and 609 which do not have the prominent conductive anomaly. Thus the data at Site 204 was discarded in the present 2-D modeling investigation. Another conductive anomaly (PC) located near the Pacific coa ...
... The apparent resistivity profile at Site 902 turned out to be very similar to those at Sites 304 and 609 which do not have the prominent conductive anomaly. Thus the data at Site 204 was discarded in the present 2-D modeling investigation. Another conductive anomaly (PC) located near the Pacific coa ...
Radiogenic Isotope Geochemistry of the Mantle
... the region occupied by the oceanic basalt data is often referred to as the “mantle array”. The second observation is that, although there is overlap, MORB have the lower 87Sr/86Sr ratios and highest εNd than OIB. Variations in radiogenic isotope ratios in basalts result from variations in parent-dau ...
... the region occupied by the oceanic basalt data is often referred to as the “mantle array”. The second observation is that, although there is overlap, MORB have the lower 87Sr/86Sr ratios and highest εNd than OIB. Variations in radiogenic isotope ratios in basalts result from variations in parent-dau ...
Pyrenean orogeny and plate kinematics
... during late Jurassic – early Cretaceous [Beràstegui et al., 1990; Martı́n-Chivelet et al., 2002; Vergés and Garcı́a-Senz, 2001]. The question of the origin of the so-called pull-apart basins has been often questioned. For example, the approximate continuity of Jurassic facies on each side of the P ...
... during late Jurassic – early Cretaceous [Beràstegui et al., 1990; Martı́n-Chivelet et al., 2002; Vergés and Garcı́a-Senz, 2001]. The question of the origin of the so-called pull-apart basins has been often questioned. For example, the approximate continuity of Jurassic facies on each side of the P ...
Whole-mantle convection with tectonic plates preserves
... recycled9, 10, and the timing of incorporation into the convecting mantle11, 12. Suggested recycled components have included lower continental crust11, sub-continental lithospheric mantle10, 11, 13, altered ocean crust ± pelagic sediments6, and subduction modified mantle9, as well as material from l ...
... recycled9, 10, and the timing of incorporation into the convecting mantle11, 12. Suggested recycled components have included lower continental crust11, sub-continental lithospheric mantle10, 11, 13, altered ocean crust ± pelagic sediments6, and subduction modified mantle9, as well as material from l ...
Volcano
... • Lava begins as _________, which usually forms in the __________________. • The materials of the asthenosphere are under great ____________. • Liquid magma is less _________ than the solid material around it. • As magma rises, it sometimes becomes _____________ beneath layers of rock. • But if an o ...
... • Lava begins as _________, which usually forms in the __________________. • The materials of the asthenosphere are under great ____________. • Liquid magma is less _________ than the solid material around it. • As magma rises, it sometimes becomes _____________ beneath layers of rock. • But if an o ...
Imag(in)ing the continental lithosphere
... preserved from continental accretion within and at the margins of the Archean cratons are subduction related, and we use subduction as an analog for scales left by past events. In modern orogenic belts we expect to find subduction structures, small scale upper mantle convection structures, and basal ...
... preserved from continental accretion within and at the margins of the Archean cratons are subduction related, and we use subduction as an analog for scales left by past events. In modern orogenic belts we expect to find subduction structures, small scale upper mantle convection structures, and basal ...
The North Palawan Block, Philippines
... difficulty therefore arises in explaining the offsetting and westward narrowing of the area occupied by oceanic crust. Two explanations are possible for these phenomena. First, they might result from an earlier phase of spreading with a different pole of rotation and with an orientation as suggested ...
... difficulty therefore arises in explaining the offsetting and westward narrowing of the area occupied by oceanic crust. Two explanations are possible for these phenomena. First, they might result from an earlier phase of spreading with a different pole of rotation and with an orientation as suggested ...
Dynamics of the Eurasian Plate
... Concerning the forces acting on the surface and edges of the plates, Bird [4] and Lithgow-Bertelloni and Guynn [22], for instance, incorporate the effects of topography and lateral density contrasts in the lithosphere and thus account for ridge push, slab pull and topographically induces stresses, b ...
... Concerning the forces acting on the surface and edges of the plates, Bird [4] and Lithgow-Bertelloni and Guynn [22], for instance, incorporate the effects of topography and lateral density contrasts in the lithosphere and thus account for ridge push, slab pull and topographically induces stresses, b ...
12.002 Physics and Chemistry of the Earth and Terrestrial Planets
... core and mantle (ie Snell’s law). The same relationships are correct for S waves incident on the core. In the Earth, and probably also the other terrestrial bodies, the seismic velocity is not uniform through the core or mantle, but increases downward due to the increased pressure acting on the mate ...
... core and mantle (ie Snell’s law). The same relationships are correct for S waves incident on the core. In the Earth, and probably also the other terrestrial bodies, the seismic velocity is not uniform through the core or mantle, but increases downward due to the increased pressure acting on the mate ...
Pdf - Wiley Online Library
... and harzburgite) account for 6%. ORT occurs in six 1–3 m thick intervals at various depths from 495 to 1235 mbsf. Two additional intervals, each many tens of meters thick, are dominated by ORT with gabbroic rocks interspersed: 310–350 mbsf and 1094–1197 mbsf. Four phases of logging were carried out ...
... and harzburgite) account for 6%. ORT occurs in six 1–3 m thick intervals at various depths from 495 to 1235 mbsf. Two additional intervals, each many tens of meters thick, are dominated by ORT with gabbroic rocks interspersed: 310–350 mbsf and 1094–1197 mbsf. Four phases of logging were carried out ...
Terrestrial aftermath of the Moon
... The connection between tidal heating and the upper bound on radiative cooling created a stable climate buffer [4,5]. Dissipation by oscillating tidal stresses for hot silicate interiors can be characterized by the Maxwell time η/Γ (where η is viscosity and Γ is shear modulus). This dissipation is st ...
... The connection between tidal heating and the upper bound on radiative cooling created a stable climate buffer [4,5]. Dissipation by oscillating tidal stresses for hot silicate interiors can be characterized by the Maxwell time η/Γ (where η is viscosity and Γ is shear modulus). This dissipation is st ...
Noble Gas Constraints on Mantle Structure and Convection
... Mantle 20Ne/22Ne ratio is fixed; 21Ne/22Ne varies because of radiogenic ingrowth and varying degrees of degassing Different ocean islands have distinct 21Ne/22Ne ratios; either reflects varying amounts of MORB mantle addition to the OIB source(s) or different parts of the mantle have been degassed a ...
... Mantle 20Ne/22Ne ratio is fixed; 21Ne/22Ne varies because of radiogenic ingrowth and varying degrees of degassing Different ocean islands have distinct 21Ne/22Ne ratios; either reflects varying amounts of MORB mantle addition to the OIB source(s) or different parts of the mantle have been degassed a ...
Discovery of a magma chamber and faults beneath a Mid
... magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers1. The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate2,3 and fast-spreading centres4,5, but it has been difficult to image such magma chambe ...
... magmatic and tectonic processes, with magmatic accretion possibly involving short-lived crustal magma chambers1. The reflections of seismic waves from crustal magma chambers have been observed beneath intermediate2,3 and fast-spreading centres4,5, but it has been difficult to image such magma chambe ...
modern and ancient incompatible element-poor adakite
... in arc magmas are thought to be mostly provided by slab-derived fluids, are comparatively less depleted (or actually enriched, as is the case for boron). Thus, mobile-to-immobile element ratios, such as the Ba/Th are anomalously high at NLV, suggesting a locally very high input of slab-derived fluid ...
... in arc magmas are thought to be mostly provided by slab-derived fluids, are comparatively less depleted (or actually enriched, as is the case for boron). Thus, mobile-to-immobile element ratios, such as the Ba/Th are anomalously high at NLV, suggesting a locally very high input of slab-derived fluid ...
Early cretaceous subduction-related adakite
... Gangdese Belt from Yawa in the west to Sangri County in the east (Fig. 1c). The general lithological features of the Mamuxia Formation are shown in Fig. 2 and summarized in Table 1. As a whole, a Late Jurassic–Early Cretaceous age for deposition of the Mamuxia Formation is indicated by fossil corals ...
... Gangdese Belt from Yawa in the west to Sangri County in the east (Fig. 1c). The general lithological features of the Mamuxia Formation are shown in Fig. 2 and summarized in Table 1. As a whole, a Late Jurassic–Early Cretaceous age for deposition of the Mamuxia Formation is indicated by fossil corals ...
Anorogenic plateau formation: The importance of density
... [1] Away from active plate boundaries the relationships between spatiotemporal variations in density and geothermal gradient are important for understanding the evolution of topography in continental interiors. In this context the classic concept of the continental lithosphere as comprising three st ...
... [1] Away from active plate boundaries the relationships between spatiotemporal variations in density and geothermal gradient are important for understanding the evolution of topography in continental interiors. In this context the classic concept of the continental lithosphere as comprising three st ...
A Geoelectric Model of the Cascadia Subduction Zone
... are discussed. A 2-D interpretation of magnetic variation and magnetotelluric data was conducted in a hypothesis-testing mode. Three hypotheses were examined: (1) fluid saturation of the lower continental crust and the absence of continental asthenosphere; (2) fluid saturation of the lower continent ...
... are discussed. A 2-D interpretation of magnetic variation and magnetotelluric data was conducted in a hypothesis-testing mode. Three hypotheses were examined: (1) fluid saturation of the lower continental crust and the absence of continental asthenosphere; (2) fluid saturation of the lower continent ...
Recent Movements of the Juan de Fuca Plate System
... Analysis of the magnetic anomaliesof the Juan de Fuca plate systemallows instantaneouspoles of rotation relative to the Pacific plate to be calculatedfrom 7 Ma to the present.By combiningthesewith global solutions for Pacific/America and "absolute" (relative to hot spot) motions, a plate motion sequ ...
... Analysis of the magnetic anomaliesof the Juan de Fuca plate systemallows instantaneouspoles of rotation relative to the Pacific plate to be calculatedfrom 7 Ma to the present.By combiningthesewith global solutions for Pacific/America and "absolute" (relative to hot spot) motions, a plate motion sequ ...
Mantle hydration and Cl-rich fluids in the subduction forearc
... which to explain the observation of reduced velocities and water storage in the forearc. Geophysical evidence for the presence of hydrated lithologies and fluids at 30–90 km depths corresponding to the deep forearc region of subduction zones will be addressed in light of recent experimental determin ...
... which to explain the observation of reduced velocities and water storage in the forearc. Geophysical evidence for the presence of hydrated lithologies and fluids at 30–90 km depths corresponding to the deep forearc region of subduction zones will be addressed in light of recent experimental determin ...
CHAPTER 13 Denudation, weathering and mass wasting
... sequence, in a tropical/equatorial marine and marine-margin environment under active crustal extension. The juxtaposition of both terranes next to each was brought about through random tectonic plate reorganization since their individual formation. The website Case Study for Chapter 12 showed how th ...
... sequence, in a tropical/equatorial marine and marine-margin environment under active crustal extension. The juxtaposition of both terranes next to each was brought about through random tectonic plate reorganization since their individual formation. The website Case Study for Chapter 12 showed how th ...
Australian Journal of Earth Sciences - ePIC
... Tectonic models for the Late Cretaceous/Tertiary evolution of the West Antarctic Rift System range from hundreds of kilometres of extension to negligible strike-slip displacement and are based on a variety of observations, as well as kinematic and geodynamic models. Most data constraining these mode ...
... Tectonic models for the Late Cretaceous/Tertiary evolution of the West Antarctic Rift System range from hundreds of kilometres of extension to negligible strike-slip displacement and are based on a variety of observations, as well as kinematic and geodynamic models. Most data constraining these mode ...
Plate tectonics
Plate tectonics (from the Late Latin tectonicus, from the Greek: τεκτονικός ""pertaining to building"") is a scientific theory that describes the large-scale motion of Earth's lithosphere. This theoretical model builds on the concept of continental drift which was developed during the first few decades of the 20th century. The geoscientific community accepted the theory after the concepts of seafloor spreading were later developed in the late 1950s and early 1960s.The lithosphere, which is the rigid outermost shell of a planet (on Earth, the crust and upper mantle), is broken up into tectonic plates. On Earth, there are seven or eight major plates (depending on how they are defined) and many minor plates. Where plates meet, their relative motion determines the type of boundary; convergent, divergent, or transform. Earthquakes, volcanic activity, mountain-building, and oceanic trench formation occur along these plate boundaries. The lateral relative movement of the plates typically varies from zero to 100 mm annually.Tectonic plates are composed of oceanic lithosphere and thicker continental lithosphere, each topped by its own kind of crust. Along convergent boundaries, subduction carries plates into the mantle; the material lost is roughly balanced by the formation of new (oceanic) crust along divergent margins by seafloor spreading. In this way, the total surface of the globe remains the same. This prediction of plate tectonics is also referred to as the conveyor belt principle. Earlier theories (that still have some supporters) propose gradual shrinking (contraction) or gradual expansion of the globe.Tectonic plates are able to move because the Earth's lithosphere has greater strength than the underlying asthenosphere. Lateral density variations in the mantle result in convection. Plate movement is thought to be driven by a combination of the motion of the seafloor away from the spreading ridge (due to variations in topography and density of the crust, which result in differences in gravitational forces) and drag, with downward suction, at the subduction zones. Another explanation lies in the different forces generated by the rotation of the globe and the tidal forces of the Sun and Moon. The relative importance of each of these factors and their relationship to each other is unclear, and still the subject of much debate.