Continental arc–island arc fluctuations, growth of crustal carbonates
... McGovern and Schubert, 1989). This is because melting at ridges is driven by passive decompression, and consequently CO2 flux through ridges scales as FVCm, where Cm is the concentration of C in the mantle, V is the half spreading rate, and F is the average melting degree (FV is the flux of oceanic ...
... McGovern and Schubert, 1989). This is because melting at ridges is driven by passive decompression, and consequently CO2 flux through ridges scales as FVCm, where Cm is the concentration of C in the mantle, V is the half spreading rate, and F is the average melting degree (FV is the flux of oceanic ...
On subducting slab entrainment of buoyant asthenosphere
... setup for the numerical calculations in that phase transitions and melting processes are not considered. Instead, we begin with a preexisting 200 km-thick asthenosphere layer with a higher temperature and more depletion than the underlying mantle and ask how quickly it can be removed by plate subduc ...
... setup for the numerical calculations in that phase transitions and melting processes are not considered. Instead, we begin with a preexisting 200 km-thick asthenosphere layer with a higher temperature and more depletion than the underlying mantle and ask how quickly it can be removed by plate subduc ...
How do subduction processes contribute to forearc Andean uplift
... Pleistocene. Rodriguez et al. (2013) observe the same coastal evolution between 30 and 32◦ S. In fact, Fuenzalida et al. (1965) had already noted that Chilean Coasts North of 40◦ S have been uplifting during the Pleistocene. These authors note that this Quaternary renewal of coastal uplift contrasts ...
... Pleistocene. Rodriguez et al. (2013) observe the same coastal evolution between 30 and 32◦ S. In fact, Fuenzalida et al. (1965) had already noted that Chilean Coasts North of 40◦ S have been uplifting during the Pleistocene. These authors note that this Quaternary renewal of coastal uplift contrasts ...
The tectonic regime along the Andes: Present
... or extensional faults of an earlier tectonic stage (Kley et al. 1999; Ramos 1999) will also exert an important control in the structural style and in localizing Andean deformation. In recent years, the influence of climate has become evident after the proposal of Montgomery et al. (2001), Lamb and D ...
... or extensional faults of an earlier tectonic stage (Kley et al. 1999; Ramos 1999) will also exert an important control in the structural style and in localizing Andean deformation. In recent years, the influence of climate has become evident after the proposal of Montgomery et al. (2001), Lamb and D ...
The role of magmatically driven lithospheric thickening on arc front
... One of the most distinctive geographic features on Earth is the series of long arcuate chains of volcanoes on the upper plate of subduction zones, where cold and hydrothermally altered oceanic lithosphere descends into the Earth’s deep interior. Arc volcanism forms one of the primary connections bet ...
... One of the most distinctive geographic features on Earth is the series of long arcuate chains of volcanoes on the upper plate of subduction zones, where cold and hydrothermally altered oceanic lithosphere descends into the Earth’s deep interior. Arc volcanism forms one of the primary connections bet ...
Experimental_laboratory_files/2004_The source of Granites
... involved has to produce low Sm/Nd and low Rb/Sr. An alternative way is to assume that I-type granites typically with low 87Sr86/Sr initial ratios are generated from a crustal source that has this particular composition. Comparison with Archaean crust array (Fig. 1a) suggests that tonalites of the lo ...
... involved has to produce low Sm/Nd and low Rb/Sr. An alternative way is to assume that I-type granites typically with low 87Sr86/Sr initial ratios are generated from a crustal source that has this particular composition. Comparison with Archaean crust array (Fig. 1a) suggests that tonalites of the lo ...
Crustal Shortening and Extension in the Central Andes: Insights
... Figure 5. (a) Predicted surface velocities across the Andes for short-term crustal deformation. Scale is shown in the upper right corner. Solid line (A-A’) indicates the location of the velocity profile in Fig. 7. (b) Predicted surface velocities for long-term crustal deformation. The non-uniform ve ...
... Figure 5. (a) Predicted surface velocities across the Andes for short-term crustal deformation. Scale is shown in the upper right corner. Solid line (A-A’) indicates the location of the velocity profile in Fig. 7. (b) Predicted surface velocities for long-term crustal deformation. The non-uniform ve ...
Drilling Active Tectonics and Magmatism (Volcanics, Geoprisms
... I. INTRODUCTION Forces originating deep within the active Earth are expressed on Earth’s surface, where they have a profound effect on human societies. On a global scale, these effects include the development of mountain ranges and subduction zones. On a local scale, they are expressed as active fau ...
... I. INTRODUCTION Forces originating deep within the active Earth are expressed on Earth’s surface, where they have a profound effect on human societies. On a global scale, these effects include the development of mountain ranges and subduction zones. On a local scale, they are expressed as active fau ...
Shear wave anisotropy beneath the Cascadia subduction zone and
... western North America to constrain regional trends in anisotropy at the Cascadia subduction zone (CSZ) and adjacent regions. At forearc stations above the Juan de Fuca Plate, the fast directions are approximately parallel to the direction of absolute plate motion of the main Juan de Fuca Plate (∼N70 ...
... western North America to constrain regional trends in anisotropy at the Cascadia subduction zone (CSZ) and adjacent regions. At forearc stations above the Juan de Fuca Plate, the fast directions are approximately parallel to the direction of absolute plate motion of the main Juan de Fuca Plate (∼N70 ...
How Plate-forming Processes Explain Structure and Shortening in
... Figure 4. Graph showing the influence of the thickness of accreted material. This depth is controlled by the position and weakness of decoupling levels in the crust. They are related to the inherited rheological layering, which illustrates the role of the thermotectonic state of the crust and litho ...
... Figure 4. Graph showing the influence of the thickness of accreted material. This depth is controlled by the position and weakness of decoupling levels in the crust. They are related to the inherited rheological layering, which illustrates the role of the thermotectonic state of the crust and litho ...
Oxygen and hydrogen isotope compositions of oceanic plutonic rocks
... hydrothermal metamorphism by seawater. Maximum temperatures of alteration are above 600°C; lower temperatures of alteration, greenschist and below, are not characteristic. Whole-rock samples and plagioclaseseparates have undergone 180 depletions associated with deformation and development of metamor ...
... hydrothermal metamorphism by seawater. Maximum temperatures of alteration are above 600°C; lower temperatures of alteration, greenschist and below, are not characteristic. Whole-rock samples and plagioclaseseparates have undergone 180 depletions associated with deformation and development of metamor ...
Barrovian metamorphism in the central Kootenay Arc, British
... Crowley et al. 2000; Reid 2003; Larson et al. 2007; Gibson et al. 2008). Early Cretaceous structures are dominant in a broad zone that stretches from the central Kootenay Arc across the Purcell Anticlinorium, as far east as the Porcupine Creek anticlinorium (Simony and Carr 2011; Fig. 1), whereas Mi ...
... Crowley et al. 2000; Reid 2003; Larson et al. 2007; Gibson et al. 2008). Early Cretaceous structures are dominant in a broad zone that stretches from the central Kootenay Arc across the Purcell Anticlinorium, as far east as the Porcupine Creek anticlinorium (Simony and Carr 2011; Fig. 1), whereas Mi ...
Metamorphism and Metamorphic Rocks - e
... a. are characterized by distinctive mineral assemblages; b. are separated from each other by isograds; c. reflect a metamorphic grade; d. all of these; e. none of these. 36. Many metamorphic rocks, for example, marble, slate, and minerals, for example, graphite and talc, are ...
... a. are characterized by distinctive mineral assemblages; b. are separated from each other by isograds; c. reflect a metamorphic grade; d. all of these; e. none of these. 36. Many metamorphic rocks, for example, marble, slate, and minerals, for example, graphite and talc, are ...
Geophysical Evidence for Mid-crustal Magma Reservoirs in the
... hazards assessment. Spatial correlations amongst various features, such as crustal manifestations of stress, faults, volcanic vents, geothermal systems, and high and low seismic velocity zones provide the main clues about where magma is and how it is transported through the lithosphere. Probabilisti ...
... hazards assessment. Spatial correlations amongst various features, such as crustal manifestations of stress, faults, volcanic vents, geothermal systems, and high and low seismic velocity zones provide the main clues about where magma is and how it is transported through the lithosphere. Probabilisti ...
Geophysical and Petrological Constraints on Ocean Plate Dynamics
... that the oceanic mantle potential temperature must be ~60 ºC hotter than current estimates. Chapter 3 goes further to provide a more accurate parameterization of the anhydrous mantle solidus from experiments over a range of pressures. This chapter concludes that the range of potential temperatures o ...
... that the oceanic mantle potential temperature must be ~60 ºC hotter than current estimates. Chapter 3 goes further to provide a more accurate parameterization of the anhydrous mantle solidus from experiments over a range of pressures. This chapter concludes that the range of potential temperatures o ...
Crustal Structure at the Continental Margin South of South Africa
... are interpreted in the light of existing seismic, gravity and magnetic results. There is a marked difference in shallow and deep crustal structure between the rifted segment of margin facing the Atlantic Ocean and the margin offset facing the Indian Ocean. Both margin segments have a mass excess ben ...
... are interpreted in the light of existing seismic, gravity and magnetic results. There is a marked difference in shallow and deep crustal structure between the rifted segment of margin facing the Atlantic Ocean and the margin offset facing the Indian Ocean. Both margin segments have a mass excess ben ...
Imaging crust and upper mantle beneath Mount Fuji, Japan, by
... flow from the PAC plate below in regions where PAC and PHS plates overlap, and the contribution of PHS fluid is distinctly small in Mount Fuji compared with other areas. To understand the magma-plumbing system of Mount Fuji, we have to clarify the seismic structure there. Various studies have explored ...
... flow from the PAC plate below in regions where PAC and PHS plates overlap, and the contribution of PHS fluid is distinctly small in Mount Fuji compared with other areas. To understand the magma-plumbing system of Mount Fuji, we have to clarify the seismic structure there. Various studies have explored ...
Seismic structure of the crust and uppermost mantle of the Capricorn
... Fortescue Group) that are interpreted to have been deposited during continental rifting (Thorne and Trendall, 2001). Evolution of the rifted margin to a passive margin was marked by the deposition of the 2.60–2.45 Ga Hamersley Group within the Hamersley Basin, which is dominated by chemical iron for ...
... Fortescue Group) that are interpreted to have been deposited during continental rifting (Thorne and Trendall, 2001). Evolution of the rifted margin to a passive margin was marked by the deposition of the 2.60–2.45 Ga Hamersley Group within the Hamersley Basin, which is dominated by chemical iron for ...
The Use of Magnetic Susceptibility of Rocks in Geological
... minerals contained in a rock. Sometimes, it is dominantly controlled by paramagnetic minerals (mafic silicates such as olivine, pyroxenes, amphiboles, micas, tourmaline, garnets), often by ferromagnetic minerals (iron oxides or sulphides, represented for instance by magnetite and/or pyrrhotite, resp ...
... minerals contained in a rock. Sometimes, it is dominantly controlled by paramagnetic minerals (mafic silicates such as olivine, pyroxenes, amphiboles, micas, tourmaline, garnets), often by ferromagnetic minerals (iron oxides or sulphides, represented for instance by magnetite and/or pyrrhotite, resp ...
Origin of carbonatites in the South Qinling orogen:
... mantle components involved in the generation of carbonatitic magmas (Tilton and Bell, 1994; Simonetti et al., 1998; Bell and Tilton, 2001, 2002). At present, the prevailing view is that these magmas are derived from a lithospheric source affected by asthenospheric upwelling or plumes involving deeper ...
... mantle components involved in the generation of carbonatitic magmas (Tilton and Bell, 1994; Simonetti et al., 1998; Bell and Tilton, 2001, 2002). At present, the prevailing view is that these magmas are derived from a lithospheric source affected by asthenospheric upwelling or plumes involving deeper ...
GIS-based Reconstruction of Pangaea with Recent
... □ A notable feature of Pangaea as reconstructed in this study is the two circular inland seas. - One corresponds to the Tethys Sea. The other corresponds to the present Arctic Ocean and is several times larger than the Tethys. - From a geological viewpoint these inland seas appear to be oceanic crus ...
... □ A notable feature of Pangaea as reconstructed in this study is the two circular inland seas. - One corresponds to the Tethys Sea. The other corresponds to the present Arctic Ocean and is several times larger than the Tethys. - From a geological viewpoint these inland seas appear to be oceanic crus ...
Geological Society of America Bulletin
... 1986; Li et al., 1992; Hauksson, 2000). The fan-like seismic reflection structure and its truncation by the Moho beneath the TehachapiRand belt (Fig. 3) is interpreted as the mark of regional flattening of an underplated-duplex complex and the related smoothing out of the Moho subsequent to lower-cr ...
... 1986; Li et al., 1992; Hauksson, 2000). The fan-like seismic reflection structure and its truncation by the Moho beneath the TehachapiRand belt (Fig. 3) is interpreted as the mark of regional flattening of an underplated-duplex complex and the related smoothing out of the Moho subsequent to lower-cr ...
Pub-2010 - Caltech GPS
... There is a seamount chain (the Moonless Mountains) on the Pacific plate between the Murray and Clarion fracture zones that may have had a correlative chain, the Chumbia seamount ridge, on the now subducted Farallon plate (KEPPIE and MORAN-ZENTENO, 2005). The seamounts in this chain do not have flexu ...
... There is a seamount chain (the Moonless Mountains) on the Pacific plate between the Murray and Clarion fracture zones that may have had a correlative chain, the Chumbia seamount ridge, on the now subducted Farallon plate (KEPPIE and MORAN-ZENTENO, 2005). The seamounts in this chain do not have flexu ...
Geophysics
Geophysics /dʒiːoʊfɪzɪks/ is a subject of natural science concerned with the physical processes and physical properties of the Earth and its surrounding space environment, and the use of quantitative methods for their analysis. The term geophysics sometimes refers only to the geological applications: Earth's shape; its gravitational and magnetic fields; its internal structure and composition; its dynamics and their surface expression in plate tectonics, the generation of magmas, volcanism and rock formation. However, modern geophysics organizations use a broader definition that includes the water cycle including snow and ice; fluid dynamics of the oceans and the atmosphere; electricity and magnetism in the ionosphere and magnetosphere and solar-terrestrial relations; and analogous problems associated with the Moon and other planets.Although geophysics was only recognized as a separate discipline in the 19th century, its origins go back to ancient times. The first magnetic compasses were made from lodestones, while more modern magnetic compasses played an important role in the history of navigation. The first seismic instrument was built in 132 BC. Isaac Newton applied his theory of mechanics to the tides and the precession of the equinox; and instruments were developed to measure the Earth's shape, density and gravity field, as well as the components of the water cycle. In the 20th century, geophysical methods were developed for remote exploration of the solid Earth and the ocean, and geophysics played an essential role in the development of the theory of plate tectonics.Geophysics is applied to societal needs, such as mineral resources, mitigation of natural hazards and environmental protection. Geophysical survey data are used to analyze potential petroleum reservoirs and mineral deposits, locate groundwater, find archaeological relics, determine the thickness of glaciers and soils, and assess sites for environmental remediation.