![nature and composition of the continental crust](http://s1.studyres.com/store/data/001265244_1-85b7dbc6c5ea5f19d1b39c95119abb51-300x300.png)
nature and composition of the continental crust
... also found in surface outcrop or as xenoliths. Amphibolite facies rocks may also be important in the lowermost crust in areas of high water flux (such as in island arc settings where hydrous oceanic lithosphere is subducted and dewatered [e.g., Kushiro, 1990]. The role the lower crust plays in conti ...
... also found in surface outcrop or as xenoliths. Amphibolite facies rocks may also be important in the lowermost crust in areas of high water flux (such as in island arc settings where hydrous oceanic lithosphere is subducted and dewatered [e.g., Kushiro, 1990]. The role the lower crust plays in conti ...
TECTONIC ANALYSIS OF NORTHWESTERN SOUTH AMERICA
... with more than 80 million people concentrated along the Andes Mountains. This region includes a complex and dangerous mosaic of tectonic plates that have produced devastating earthquakes, tsunamis, volcanic eruptions and landslides in the last decades. The region’s economic development has also seri ...
... with more than 80 million people concentrated along the Andes Mountains. This region includes a complex and dangerous mosaic of tectonic plates that have produced devastating earthquakes, tsunamis, volcanic eruptions and landslides in the last decades. The region’s economic development has also seri ...
Structure and evolution of the continental margin off Norway and the
... It has been suggested that the main Late Paleozoic–early Mesozoic rift episodes took place in mid-Carboniferous, Carboniferous–Permian and Permian–Early Triassic times (Doré, 1991). Sediment packages associated with these movements are poorly resolved, mainly because of overprint by younger tectonis ...
... It has been suggested that the main Late Paleozoic–early Mesozoic rift episodes took place in mid-Carboniferous, Carboniferous–Permian and Permian–Early Triassic times (Doré, 1991). Sediment packages associated with these movements are poorly resolved, mainly because of overprint by younger tectonis ...
Origin of carbonatites in the South Qinling orogen:
... Pb isotopic trend toward HIMU in the SQ carbonatites. We conclude that their parental magma was derived from a source incorporating the Mianlue oceanic crust mixed with an asthenospheric (or deeper) material characterized by high Pb and low Nd isotopic values. This material represents a deep-seated ...
... Pb isotopic trend toward HIMU in the SQ carbonatites. We conclude that their parental magma was derived from a source incorporating the Mianlue oceanic crust mixed with an asthenospheric (or deeper) material characterized by high Pb and low Nd isotopic values. This material represents a deep-seated ...
poster technical sessions
... Locating on Eurasian border zone of on-going collision between Eurasian and Arabian plates and within the one of the most prominent orogenic belts of neo-tectonic era, Anatolian terrane also includes the other deforming structures associated with the same period, such as (possibly being reactivation ...
... Locating on Eurasian border zone of on-going collision between Eurasian and Arabian plates and within the one of the most prominent orogenic belts of neo-tectonic era, Anatolian terrane also includes the other deforming structures associated with the same period, such as (possibly being reactivation ...
IODP Proposal Cover Sheet
... (IBM) arc that aim at comprehensive understanding of arc evolution and continental crust formation. We propose to drill a deep hole that penetrates through a complete sequence of intra-oceanic arc upper crust and into the in situ middle crust that may be a nucleus of continental crust. The average c ...
... (IBM) arc that aim at comprehensive understanding of arc evolution and continental crust formation. We propose to drill a deep hole that penetrates through a complete sequence of intra-oceanic arc upper crust and into the in situ middle crust that may be a nucleus of continental crust. The average c ...
Geochemistry of mafic rocks and melt inclusions and their
... small-scale magma intrusions commonly occurred within the crust (Mccaig and Harris, 2012). The lack of a steady-state magma chamber makes it difficult to form corresponding hydrothermal systems. However, once a hydrothermal system was formed in this setting, it would not be as easily damaged by freq ...
... small-scale magma intrusions commonly occurred within the crust (Mccaig and Harris, 2012). The lack of a steady-state magma chamber makes it difficult to form corresponding hydrothermal systems. However, once a hydrothermal system was formed in this setting, it would not be as easily damaged by freq ...
UHP metamorphism in garnet peridotite, Cuaba unit, Rio San Juan
... magnesiohornblende + late serpentine) and a corundum-bearing variant are associated with hornblende gneiss and schist (hornblende + plagioclase + quartz + rutile +/- garnet +/- biotite +/epidote) and retrograded eclogite (hornblende + symplectic diopside-plagioclase + garnet + quartz +/epidote) in t ...
... magnesiohornblende + late serpentine) and a corundum-bearing variant are associated with hornblende gneiss and schist (hornblende + plagioclase + quartz + rutile +/- garnet +/- biotite +/epidote) and retrograded eclogite (hornblende + symplectic diopside-plagioclase + garnet + quartz +/epidote) in t ...
10. Regional Geophysics and Structural Framework of the
... main portion of the Juan de Fuca Plate has been converging toward the northeast and underthrusting the continent since the Eocene. The present rate of convergence increases slightly northward and is about 45 mm/yr off southern Vancouver Island; the direction is approximately orthogonal to the margin ...
... main portion of the Juan de Fuca Plate has been converging toward the northeast and underthrusting the continent since the Eocene. The present rate of convergence increases slightly northward and is about 45 mm/yr off southern Vancouver Island; the direction is approximately orthogonal to the margin ...
Dynamical geochemistry of the mantle
... transition zone, and especially at the 660 km seismic discontinuity, was resolved in the negative by two arguments. The first (Davies, 1988b) is that such a compositional boundary would give rise to plumes that are much stronger than is consistent with observed hotspot swells. This argument will be ...
... transition zone, and especially at the 660 km seismic discontinuity, was resolved in the negative by two arguments. The first (Davies, 1988b) is that such a compositional boundary would give rise to plumes that are much stronger than is consistent with observed hotspot swells. This argument will be ...
Nonvolcanic Seafloor Spreading and Corner
... (Figures 4 and 5). Both these observations, together with the overall form of the bathymetry, are consistent with nonvolcanic seafloor generated by slip on large-displacement faults that undergo greater slip and more rotation than faults cutting the volcanic terrain. Steeper slopes that dip away fro ...
... (Figures 4 and 5). Both these observations, together with the overall form of the bathymetry, are consistent with nonvolcanic seafloor generated by slip on large-displacement faults that undergo greater slip and more rotation than faults cutting the volcanic terrain. Steeper slopes that dip away fro ...
letters - Noble Gas Geochemistry Lab
... MORB, with Dupal characteristics dominating along ,350 km of the spreading axis. Their occurrence in Arctic MORB shows that Dupal characteristics are not simply an attribute of the Indian–South Atlantic oceanic mantle, but reflect processes that are more general. The small geographical scale and wel ...
... MORB, with Dupal characteristics dominating along ,350 km of the spreading axis. Their occurrence in Arctic MORB shows that Dupal characteristics are not simply an attribute of the Indian–South Atlantic oceanic mantle, but reflect processes that are more general. The small geographical scale and wel ...
Equatorial Segment of the Mid-Atlantic Ridge: initial results of the
... These technological innovations have resulted in the collection of an abundance of good quality data which in turn have stimulated the development of new ideas and concepts, The complexity of the seafloor and the inhomogeneity of the crust and mantle in both oceanic and continental areas, which is b ...
... These technological innovations have resulted in the collection of an abundance of good quality data which in turn have stimulated the development of new ideas and concepts, The complexity of the seafloor and the inhomogeneity of the crust and mantle in both oceanic and continental areas, which is b ...
Geology of the Gorny Altai subduction–accretion complex, southern
... The Gorny Altai region in southern Siberia is one of the key areas in reconstructing the tectonic evolution of the western segment of the Central Asian Orogenic Belt (CAOB). This region features various orogenic elements of Late Neoproterozoic–Early Paleozoic age, such as an accretionary complex (AC ...
... The Gorny Altai region in southern Siberia is one of the key areas in reconstructing the tectonic evolution of the western segment of the Central Asian Orogenic Belt (CAOB). This region features various orogenic elements of Late Neoproterozoic–Early Paleozoic age, such as an accretionary complex (AC ...
How Did Early Earth Become Our Modern World?
... or atmosphere formation show surprisingly muted evidence of the fractionation expected during magma ocean crystallization, and even this minimal evidence for early intramantle differentiation appears to have been erased by mantle convection within ∼1.5 billion years of Earth formation. By 4.36 Ga, E ...
... or atmosphere formation show surprisingly muted evidence of the fractionation expected during magma ocean crystallization, and even this minimal evidence for early intramantle differentiation appears to have been erased by mantle convection within ∼1.5 billion years of Earth formation. By 4.36 Ga, E ...
accepted manuscript
... along the Eurasian margin is compounded by competing alternative models proposed for the breakup of East Gondwana, which are built from syntheses of geophysical and geological data but often without regional kinematic constraints. As a result, the proposed extent of Greater India varies by up to sev ...
... along the Eurasian margin is compounded by competing alternative models proposed for the breakup of East Gondwana, which are built from syntheses of geophysical and geological data but often without regional kinematic constraints. As a result, the proposed extent of Greater India varies by up to sev ...
The Upper Mantle Geoid: Implications for Continental Structure and
... continental lithosphere, and it is timely to reevaluate plate-scale estimates of the GPE, using the geoid filtered to extract the upper mantle contribution. ...
... continental lithosphere, and it is timely to reevaluate plate-scale estimates of the GPE, using the geoid filtered to extract the upper mantle contribution. ...
Ophiolite concept and its evolution
... Ophiolite concept and its evolution to lopolithic intrusions that differentiated in place. This idea of alpine-type peridotites caused a temporary setback early in the twentieth Century in the American geologists’ understanding of the significance of the genetic link between plutonic-volcanic and u ...
... Ophiolite concept and its evolution to lopolithic intrusions that differentiated in place. This idea of alpine-type peridotites caused a temporary setback early in the twentieth Century in the American geologists’ understanding of the significance of the genetic link between plutonic-volcanic and u ...
83. Tectonic Synthesis and Implications of Japan Sea ODP Drilling
... better understood than any marginal basin in the world. Our understanding of the crustal structure was enhanced with data obtained from a borehole seismometer emplaced at Site 794 during Leg 128 (Shinohara et al., this volume). Based on published refraction results and new high resolution seismic da ...
... better understood than any marginal basin in the world. Our understanding of the crustal structure was enhanced with data obtained from a borehole seismometer emplaced at Site 794 during Leg 128 (Shinohara et al., this volume). Based on published refraction results and new high resolution seismic da ...
SeiSmological grand challengeS in UnderStanding earth`S
... elasticity, and applied mathematics. Modern seismological systems utilize state-of-theart digital ground motion recording sensors and real-time communications systems, and anyone can openly access many seismological data archives. Seismologists “keep their ear” on Earth’s internal systems, listening ...
... elasticity, and applied mathematics. Modern seismological systems utilize state-of-theart digital ground motion recording sensors and real-time communications systems, and anyone can openly access many seismological data archives. Seismologists “keep their ear” on Earth’s internal systems, listening ...
Thermal structure of the shallow upper mantle beneath Italy and
... and phlogopite (up to 10 vol.%) reflect the occurrence of metasomatic events caused by fluids and/or melts rich in water. In subduction zones, the presence of phlogopite may derive from the interaction between slab-released fluids and mantle peridotite (Wyllie and Sekine, 1982; Sassi et al., 1994). The ...
... and phlogopite (up to 10 vol.%) reflect the occurrence of metasomatic events caused by fluids and/or melts rich in water. In subduction zones, the presence of phlogopite may derive from the interaction between slab-released fluids and mantle peridotite (Wyllie and Sekine, 1982; Sassi et al., 1994). The ...
MANTLE MIXING - Earth and Environmental Sciences
... Key Words mantle geochemistry, plumes, ocean island basalts, mantle heterogeneity, seismology, noble gases, layered mantle, trace elements, radiogenic isotopes ■ Abstract Observations of the geochemical diversity of mid-oceanic ridge and ocean-island basalts have traditionally been attributed to the ...
... Key Words mantle geochemistry, plumes, ocean island basalts, mantle heterogeneity, seismology, noble gases, layered mantle, trace elements, radiogenic isotopes ■ Abstract Observations of the geochemical diversity of mid-oceanic ridge and ocean-island basalts have traditionally been attributed to the ...
Ultrahigh-pressure metamorphism: tracing continental crust into the
... One of the key features in the theory of plate tectonics is the opposition of a young, continuously renewed and subducted oceanic lithosphere, to an old and everlasting continental lithosphere. In this paradigm, continental crust was assigned, because of its low density, the role of a £oating object ...
... One of the key features in the theory of plate tectonics is the opposition of a young, continuously renewed and subducted oceanic lithosphere, to an old and everlasting continental lithosphere. In this paradigm, continental crust was assigned, because of its low density, the role of a £oating object ...
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.