Magnetotelluric Studies at the San Andreas Fault Zone: Implications
... (Hickman et al. 2004), and a range of geological, geochemical, and geophysical exploration and monitoring programs have tremendously increased our knowledge about physical and chemical processes within and surrounding the fault zone, making the SAF the best studied fault zone on Earth. However, fund ...
... (Hickman et al. 2004), and a range of geological, geochemical, and geophysical exploration and monitoring programs have tremendously increased our knowledge about physical and chemical processes within and surrounding the fault zone, making the SAF the best studied fault zone on Earth. However, fund ...
Did westward subduction cause Cretaceous
... from Alaska to southern Mexico, and from east to west over much of its length the orogen comprises an easterly vergent fold-thrust belt, a complexly deformed metamorphic hinterland that collapsed gravitationally, and an interlaced mosaic of exotic terranes. Although most models for the development o ...
... from Alaska to southern Mexico, and from east to west over much of its length the orogen comprises an easterly vergent fold-thrust belt, a complexly deformed metamorphic hinterland that collapsed gravitationally, and an interlaced mosaic of exotic terranes. Although most models for the development o ...
Chapter 11
... Collisions between Continental and Oceanic Crust • Some mountains form when oceanic lithosphere and continental lithosphere collide at convergent plate boundaries. • In this type of collision, the oceanic lithosphere subducts beneath the continental lithosphere, producing large-scale deformation whi ...
... Collisions between Continental and Oceanic Crust • Some mountains form when oceanic lithosphere and continental lithosphere collide at convergent plate boundaries. • In this type of collision, the oceanic lithosphere subducts beneath the continental lithosphere, producing large-scale deformation whi ...
Sabzevar Ophiolite, NE Iran - The University of Texas at Dallas
... Harzburgite, lherzolite, dunite and chromitite are the major components of the Sabzevar mantle sequence (Fig. 4A). Harzburgites are crosscut by diabasic, gabbroic, gabbro-pegmatitic, wehrlitic and pyroxenitic dikes (Fig. 3). Gabbroic dike swarms, averaging 3–5 m thick, injected into mantle harzburgi ...
... Harzburgite, lherzolite, dunite and chromitite are the major components of the Sabzevar mantle sequence (Fig. 4A). Harzburgites are crosscut by diabasic, gabbroic, gabbro-pegmatitic, wehrlitic and pyroxenitic dikes (Fig. 3). Gabbroic dike swarms, averaging 3–5 m thick, injected into mantle harzburgi ...
Geodynamics of the Yellowstone hotspot and mantle plume: Seismic
... Integration of geophysical and geological data show that the Yellowstone hotspot resulted from a mantle plume interacting with the overriding North America plate, a process that has highly modified continental lithosphere by magmatic and tectonic processes and produced the 16-17 Ma, 700-km-long Yello ...
... Integration of geophysical and geological data show that the Yellowstone hotspot resulted from a mantle plume interacting with the overriding North America plate, a process that has highly modified continental lithosphere by magmatic and tectonic processes and produced the 16-17 Ma, 700-km-long Yello ...
The East African rift system - Department of Earth and Planetary
... main tectonic features—with emphasis on the tension fractures—and volcanism in its relationships with the tectonics. The most characteristic features in the EARS are narrow elongate zones of thinned continental lithosphere related to asthenospheric intrusions in the upper mantle. This hidden part of ...
... main tectonic features—with emphasis on the tension fractures—and volcanism in its relationships with the tectonics. The most characteristic features in the EARS are narrow elongate zones of thinned continental lithosphere related to asthenospheric intrusions in the upper mantle. This hidden part of ...
structural geology of the western branch of the east african rift
... The East African Rift System (EARS) is a classic example of continental rifting and provides an excellent framework to study extensional magmatism and the evolution of several central volcanic systems which have formed along the rift from the Tertiary to Recent. Many of the volcanic structures have ...
... The East African Rift System (EARS) is a classic example of continental rifting and provides an excellent framework to study extensional magmatism and the evolution of several central volcanic systems which have formed along the rift from the Tertiary to Recent. Many of the volcanic structures have ...
GSA TODAY - Geological Society of America
... “backarc” seafloor spreading behind a migratory east-facing intraoceanic island arc, which collided with the west-facing Sierran arc along the continental margin (as intervening oceanic lithosphere was consumed), to lodge the migratory arc and its backarc seafloor against the continental margin; (2) ...
... “backarc” seafloor spreading behind a migratory east-facing intraoceanic island arc, which collided with the west-facing Sierran arc along the continental margin (as intervening oceanic lithosphere was consumed), to lodge the migratory arc and its backarc seafloor against the continental margin; (2) ...
Long-Term Volumetric Eruption Rates and Magma Budgets Scott M
... from 1982-2004 for a total of 170 estimates. We also endeavor to establish some scaling relationships based primarily on the compilation and some simple energy budget considerations with the goal of discovering possible systematic trends in the data. 1.1. Sources and Quality of the Data The data pre ...
... from 1982-2004 for a total of 170 estimates. We also endeavor to establish some scaling relationships based primarily on the compilation and some simple energy budget considerations with the goal of discovering possible systematic trends in the data. 1.1. Sources and Quality of the Data The data pre ...
Crustal contamination of mafic magmas: evidence from a
... The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe – Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs ...
... The mid-Proterozoic Isortoq dike swarm in the Gardar Province, South Greenland, comprises a variety of alkaline rocks ranging from gabbroic to syenitic in composition. Major magmatic mineral phases are olivine, clinopyroxene, Fe – Ti oxides, amphibole, plagioclase and alkali feldspar. Quartz occurs ...
Vertical stretching and crustal thickening at Nanga Parbat, Pakistan
... [9] The dual attributes of structural continuity and a young, penetrative high temperature metamorphic/magmatic overprint through the massif are critical to our study. Faults and other structures that crosscut the peak metamorphic fabrics or which deform the leucogranites have formed relatively late ...
... [9] The dual attributes of structural continuity and a young, penetrative high temperature metamorphic/magmatic overprint through the massif are critical to our study. Faults and other structures that crosscut the peak metamorphic fabrics or which deform the leucogranites have formed relatively late ...
Journal of Volcanology and Geothermal Research
... Integration of geophysical and geological data show that the Yellowstone hotspot resulted from a mantle plume interacting with the overriding North America plate, a process that has highly modified continental lithosphere by magmatic and tectonic processes and produced the 16-17 Ma, 700-km-long Yello ...
... Integration of geophysical and geological data show that the Yellowstone hotspot resulted from a mantle plume interacting with the overriding North America plate, a process that has highly modified continental lithosphere by magmatic and tectonic processes and produced the 16-17 Ma, 700-km-long Yello ...
Behavior of subducting sediments beneath an arc under a high
... has demonstrated that a high temperature condition required for sediment melting can be developed beneath the Setouchi area (Furukawa and Tatsumi, 1999); and (3) The Setouchi HMAs and basalt can coexist with mantle peridotite (Tatsumi, 1982). Although the mixing process of the mantle peridotite with ...
... has demonstrated that a high temperature condition required for sediment melting can be developed beneath the Setouchi area (Furukawa and Tatsumi, 1999); and (3) The Setouchi HMAs and basalt can coexist with mantle peridotite (Tatsumi, 1982). Although the mixing process of the mantle peridotite with ...
as a PDF
... on a 5 -axis universal stage equipped with a proper upper hemisphere and slide for fabric analyses. Usually 100 olivine grains were selected for orientation from each specimen. Each grain was located on the photograph and rotations of the universal stage axes and positions of the olivine axes after ...
... on a 5 -axis universal stage equipped with a proper upper hemisphere and slide for fabric analyses. Usually 100 olivine grains were selected for orientation from each specimen. Each grain was located on the photograph and rotations of the universal stage axes and positions of the olivine axes after ...
evolution of the north american cordillera
... ways, as the Atlantic and Indian oceans opened to disrupt Pangea by seafloor spreading. Alpine-Himalayan evolution has involved the successive juxtaposition of disparate continental blocks (e.g., Africa, India, Australia against Eurasia) at suture belts marking the former positions of trenches where ...
... ways, as the Atlantic and Indian oceans opened to disrupt Pangea by seafloor spreading. Alpine-Himalayan evolution has involved the successive juxtaposition of disparate continental blocks (e.g., Africa, India, Australia against Eurasia) at suture belts marking the former positions of trenches where ...
EVOLUTION OF THE NORTH AMERICAN CORDILLERA William R
... ways, as the Atlantic and Indian oceans opened to disrupt Pangea by seafloor spreading. Alpine-Himalayan evolution has involved the successive juxtaposition of disparate continental blocks (e.g., Africa, India, Australia against Eurasia) at suture belts marking the former positions of trenches where ...
... ways, as the Atlantic and Indian oceans opened to disrupt Pangea by seafloor spreading. Alpine-Himalayan evolution has involved the successive juxtaposition of disparate continental blocks (e.g., Africa, India, Australia against Eurasia) at suture belts marking the former positions of trenches where ...
Download PDF-format reprint
... he also measured Q for S waves finding values of 700 at 12 s and 400 at 24 s. Press (1956) also determined Q for S waves finding it to be 500 or less. Evernden (1955) studied the arrival directions of SV-, Rayleigh- and Love-wave phases using a tripartite array in California and found that all of th ...
... he also measured Q for S waves finding values of 700 at 12 s and 400 at 24 s. Press (1956) also determined Q for S waves finding it to be 500 or less. Evernden (1955) studied the arrival directions of SV-, Rayleigh- and Love-wave phases using a tripartite array in California and found that all of th ...
Cr-Pyrope Garnets in the Lithospheric Mantle. I
... volcanic rock types, and found that the mean composition of such garnets varies systematically according to the tectonothermal age of the crust intruded by the host volcanic rock. This work defined major differences in mantle composition between regions with Archean crust and younger areas, and indi ...
... volcanic rock types, and found that the mean composition of such garnets varies systematically according to the tectonothermal age of the crust intruded by the host volcanic rock. This work defined major differences in mantle composition between regions with Archean crust and younger areas, and indi ...
Deep Earth Structure – Q of the Earth from Crust to Core.
... In order to reconcile teleseismic S–P differential traveltimes measured by handpicking, on the one hand, and by comparison of observed and synthetic seismograms, on the other, Oki et al.l (2000) found that a frequency dependence with 0.04 needs to be introduced in the reference PREM Q model (Dzi ...
... In order to reconcile teleseismic S–P differential traveltimes measured by handpicking, on the one hand, and by comparison of observed and synthetic seismograms, on the other, Oki et al.l (2000) found that a frequency dependence with 0.04 needs to be introduced in the reference PREM Q model (Dzi ...
body waves tomography from obs-recorded earthquakes
... resolution P- and S-velocity distributions across the Gulf of Cadiz region. These velocity models are obtained using 3D seismic tomography to invert the OBS data-set. The results show that the patterns of anomalies in the Gulf of Cadiz are in general, oriented in NE-SW and NW-SE directions. They als ...
... resolution P- and S-velocity distributions across the Gulf of Cadiz region. These velocity models are obtained using 3D seismic tomography to invert the OBS data-set. The results show that the patterns of anomalies in the Gulf of Cadiz are in general, oriented in NE-SW and NW-SE directions. They als ...
The nails
... of the epidermis (the nail fold) on the back of the terminal phalanx of each digit. The matrix runs from the proximal end of the floor of the nail fold to the distal margin of lunule. From this area the nail plate grows forward over the nail bed, ending in a free margin at the tip of the digit. Long ...
... of the epidermis (the nail fold) on the back of the terminal phalanx of each digit. The matrix runs from the proximal end of the floor of the nail fold to the distal margin of lunule. From this area the nail plate grows forward over the nail bed, ending in a free margin at the tip of the digit. Long ...
Serpentinite - Elements Magazine
... derived by intergranular diffusion of aqueous Mg and Si from host serpentinite, provides a geochemical test of this model by showing a peak frequency at Mg# = 97 (Evans et al. 2012, Fig. 14). Lizardite compositions have a similarly placed frequency maximum (Mg# = 96–97), but in contrast to chrysotil ...
... derived by intergranular diffusion of aqueous Mg and Si from host serpentinite, provides a geochemical test of this model by showing a peak frequency at Mg# = 97 (Evans et al. 2012, Fig. 14). Lizardite compositions have a similarly placed frequency maximum (Mg# = 96–97), but in contrast to chrysotil ...
The Asia–Kohistan–India Collision: Review and Discussion
... Thrust and Main Boundary Thrust in the Himalayas brings further confusion since these two latter thrusts are proven, intra-continental shear zones whereas the southern border of Kohistan actually is a suture zone between two different plates. The geological Kohistan has been identified as an obducte ...
... Thrust and Main Boundary Thrust in the Himalayas brings further confusion since these two latter thrusts are proven, intra-continental shear zones whereas the southern border of Kohistan actually is a suture zone between two different plates. The geological Kohistan has been identified as an obducte ...
Triggering of the largest Deccan eruptions by the Chicxulub impact
... eruptions of the Deccan continental flood basalt province suggest that these three events may have occurred within less than about a hundred thousand years of each other. Partial melting induced by the Chicxulub event does not provide an energetically plausible explanation for this coincidence, and ...
... eruptions of the Deccan continental flood basalt province suggest that these three events may have occurred within less than about a hundred thousand years of each other. Partial melting induced by the Chicxulub event does not provide an energetically plausible explanation for this coincidence, and ...
Thematic Article Tethyan ophiolites and Pangea break-up
... as a result of transtension along a large left-lateral east–west shear zone along the future boundary between Laurasia and Gondwana (Fig. 2). This area of thinned continental crust was covered by shallow seas, and with progressive crustal thinning it evolved into a series of platforms and basins, tr ...
... as a result of transtension along a large left-lateral east–west shear zone along the future boundary between Laurasia and Gondwana (Fig. 2). This area of thinned continental crust was covered by shallow seas, and with progressive crustal thinning it evolved into a series of platforms and basins, tr ...
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.