Destruction of the North China Craton: a perspective based on
... Our results show a significant deepening of the 410 km discontinuity beneath the northern part of the Trans-North China Orogen and the eastern NCC (410 km discontinuity >400 km) (Fig. 6). A similar feature is also observed for the 660 km discontinuity (Fig. 7) (660 km discontinuity >655 km) in these ...
... Our results show a significant deepening of the 410 km discontinuity beneath the northern part of the Trans-North China Orogen and the eastern NCC (410 km discontinuity >400 km) (Fig. 6). A similar feature is also observed for the 660 km discontinuity (Fig. 7) (660 km discontinuity >655 km) in these ...
Mantle mixing - Earth and Environmental Sciences
... enriched components that have compositions quite unlike primitive mantle. Similarly, the constancy of Nb/U and Ce/Pb (Hofmann, 1986; Newsom et al., 1986) suggests that there is no current reservoir with primitive mantle ratios. Interestingly, there is a strong correlation between a depleted componen ...
... enriched components that have compositions quite unlike primitive mantle. Similarly, the constancy of Nb/U and Ce/Pb (Hofmann, 1986; Newsom et al., 1986) suggests that there is no current reservoir with primitive mantle ratios. Interestingly, there is a strong correlation between a depleted componen ...
Magnitude 7.8 SW OF SUMATRA, INDONESIA
... Large strike-slip earthquakes are uncommon, but they do occur. Since the December 2004 M 9.1 earthquake that ruptured a 1300 km long segment of the Sumatran megathrust plate boundary, three large strike-slip events have occurred in this region. ...
... Large strike-slip earthquakes are uncommon, but they do occur. Since the December 2004 M 9.1 earthquake that ruptured a 1300 km long segment of the Sumatran megathrust plate boundary, three large strike-slip events have occurred in this region. ...
Sum4_Flatslabs
... Continuing questions and discussion: 1. In Mexico there is a flat slab and mineralization goes all the way inland, not just in a narrow band of porphyry as in South America. How does this fit with the above model? There are not good crustal thickness estimates for this region of Mexico, so correlat ...
... Continuing questions and discussion: 1. In Mexico there is a flat slab and mineralization goes all the way inland, not just in a narrow band of porphyry as in South America. How does this fit with the above model? There are not good crustal thickness estimates for this region of Mexico, so correlat ...
Anisotropy of the flexural response of the lithosphere in the
... [16] Throughout the Canadian Shield, there is a strong correlation between tectonic features, seismic, electrical conductivity, and flexural anisotropy (Figure 1). In the westernmost part of the Canadian Shield, the weak axis is perpendicular to the seismic fast axis [Shragge et al., 2002] and the h ...
... [16] Throughout the Canadian Shield, there is a strong correlation between tectonic features, seismic, electrical conductivity, and flexural anisotropy (Figure 1). In the westernmost part of the Canadian Shield, the weak axis is perpendicular to the seismic fast axis [Shragge et al., 2002] and the h ...
Proto-Oceanic Crust in the North and South Atlantic
... Offshore areas of the North and South Atlantic have been examined in this context. These areas include offshore Nova Scotia, Newfoundland, Labrador, Greenland, the Iberian Peninsula, Morocco, East Coast of the United States, Gulf of Guinea, Gabon, Angola and Brazil. Prospectivety in these areas vari ...
... Offshore areas of the North and South Atlantic have been examined in this context. These areas include offshore Nova Scotia, Newfoundland, Labrador, Greenland, the Iberian Peninsula, Morocco, East Coast of the United States, Gulf of Guinea, Gabon, Angola and Brazil. Prospectivety in these areas vari ...
Plate Tectonics - The Web site cannot be found
... of the m a n t l e material (about 1250oC for peridotitic rock), the outermost layer of the mantle is frozen. We call this solid rock layer having a thickness of ca. 100 km the lithosphere. The lithosphere surrounds the viscous mantle and thermally isolates it completely from the Earth’s cold upper ...
... of the m a n t l e material (about 1250oC for peridotitic rock), the outermost layer of the mantle is frozen. We call this solid rock layer having a thickness of ca. 100 km the lithosphere. The lithosphere surrounds the viscous mantle and thermally isolates it completely from the Earth’s cold upper ...
2.03 Sampling Mantle Heterogeneity through Oceanic Basalts
... decay systems with sufficiently long half-lives, such as the Rb – Sr and the Sm – Nd systems, so that lt p 1 and elt 2 1 < lt: Therefore, the isotope ratio 87Sr/86Sr in a system, such as some volume of mantle rock, is a linear function of the parent/ daughter chemical ratio Rb/Sr and a nearly linear ...
... decay systems with sufficiently long half-lives, such as the Rb – Sr and the Sm – Nd systems, so that lt p 1 and elt 2 1 < lt: Therefore, the isotope ratio 87Sr/86Sr in a system, such as some volume of mantle rock, is a linear function of the parent/ daughter chemical ratio Rb/Sr and a nearly linear ...
Continental breakup and the onset of ultraslow seafloor spreading
... thins to ,1.3 km and exhibits an unusual, highly reflective layering. We propose that a period of magma starvation led to exhumation of mantle in an oceanic core complex that was subsequently buried by deep-marine sheet flows to form this layering. Subsequent seafloor spreading formed normal, ;6-km- ...
... thins to ,1.3 km and exhibits an unusual, highly reflective layering. We propose that a period of magma starvation led to exhumation of mantle in an oceanic core complex that was subsequently buried by deep-marine sheet flows to form this layering. Subsequent seafloor spreading formed normal, ;6-km- ...
Energy of plate tectonics calculation and projection
... internal heat. The internal heat exchange with ocean is limited by surface evaporation, which is constant, and surface water radiation is limited by surface water convection as well. Because the young plates regenerated at midocean ridges are hot, ductile, and relatively thin, major seismic events a ...
... internal heat. The internal heat exchange with ocean is limited by surface evaporation, which is constant, and surface water radiation is limited by surface water convection as well. Because the young plates regenerated at midocean ridges are hot, ductile, and relatively thin, major seismic events a ...
Notes and Discussions RICHARD H. SILLITOE Institute de
... mantle at the East Pacific Rise, transported to the margins of the Pacific basin and thrust beneath the continental margins by the process of sea-floor spreading. This model surmounts the problem of envisaging the existence in the crust or upper mantle of long, narrow zones characterized by a concen ...
... mantle at the East Pacific Rise, transported to the margins of the Pacific basin and thrust beneath the continental margins by the process of sea-floor spreading. This model surmounts the problem of envisaging the existence in the crust or upper mantle of long, narrow zones characterized by a concen ...
Lithospheric strength variations in Mainland China: Tectonic
... (<500 km). Li et al. [2013] have recently presented a surface wave velocity model for the crust and upper mantle of East Asia, obtained by inverting Rayleigh wave group velocity data for periods between 10 and 145 s and combining the results with previously published Rayleigh wave phase velocity mea ...
... (<500 km). Li et al. [2013] have recently presented a surface wave velocity model for the crust and upper mantle of East Asia, obtained by inverting Rayleigh wave group velocity data for periods between 10 and 145 s and combining the results with previously published Rayleigh wave phase velocity mea ...
The ocean-continent transition in the uniform lithospheric stretching
... transition from the stretched continental lithosphere to the accreted oceanic lithosphere. In particular, we examine whether the stretching model can account for the existence of deep continental margin basins. The Armorican deep continental margin basin is taken as an example. The method proposed b ...
... transition from the stretched continental lithosphere to the accreted oceanic lithosphere. In particular, we examine whether the stretching model can account for the existence of deep continental margin basins. The Armorican deep continental margin basin is taken as an example. The method proposed b ...
Ringwood Phase transformations and their bearing on the
... and petrological studies of the complementary relationships between basaltic magmas and refractory peridotites. The phase transformations which are experienced by pyrolite between depths of 100-800 km are reviewed in some detail, particularly with regard to their capacity to explain the seismic P an ...
... and petrological studies of the complementary relationships between basaltic magmas and refractory peridotites. The phase transformations which are experienced by pyrolite between depths of 100-800 km are reviewed in some detail, particularly with regard to their capacity to explain the seismic P an ...
Mantle-driven deformation of orogenic zones and clutch tectonics
... there is no mechanical connection, plate tectonics is either independent or, at a minimum, does not have a simple relationship to mantle convection. This basic realization has recently emerged as one of the most fundamental problems of modem tectonics. In this contribution, we synthesize geological, ...
... there is no mechanical connection, plate tectonics is either independent or, at a minimum, does not have a simple relationship to mantle convection. This basic realization has recently emerged as one of the most fundamental problems of modem tectonics. In this contribution, we synthesize geological, ...
Volcano
... • As magma rises toward the surface, the pressure of the surrounding rock on the magma _____________. • When a volcano erupts, the _________ of the expanding gases pushes magma from the ____________________ through the __________ until it _________ or explodes out of the vent. • Once magma escapes f ...
... • As magma rises toward the surface, the pressure of the surrounding rock on the magma _____________. • When a volcano erupts, the _________ of the expanding gases pushes magma from the ____________________ through the __________ until it _________ or explodes out of the vent. • Once magma escapes f ...
Serpentinites - Elements Magazine
... Serpentinization of peridotite is accompanied by the release of hydrogen gas, a phenomenon recognized more than 50 years ago (Sleep et al. 2004; Evans et al. 2013). The hydrogen and other reduced gases produced during serpentinization provide a unique ecosystem on the deep seafloor (Ohara et al. 201 ...
... Serpentinization of peridotite is accompanied by the release of hydrogen gas, a phenomenon recognized more than 50 years ago (Sleep et al. 2004; Evans et al. 2013). The hydrogen and other reduced gases produced during serpentinization provide a unique ecosystem on the deep seafloor (Ohara et al. 201 ...
Earthquake Depth-Energy Release: Thermomechanical Implications
... coincident with the low velocity zone, is consistent with the presence of a partial melt phase (Presnall and ...
... coincident with the low velocity zone, is consistent with the presence of a partial melt phase (Presnall and ...
Crust and upper mantle discontinuity structure beneath eastern
... refraction profiles and because individual refraction profiles manifest considerable variation even within given tectonic terranes, we did not assume different crustal velocities for different segments of the array. Rather, we modeled all observed crustal receiver functions with three Vp and Vp /Vs ...
... refraction profiles and because individual refraction profiles manifest considerable variation even within given tectonic terranes, we did not assume different crustal velocities for different segments of the array. Rather, we modeled all observed crustal receiver functions with three Vp and Vp /Vs ...
6/page
... trenches The oceanic crust is a thin layer on top of a convecting mantle Continents as rafts of lighter material -‘bump’ into each other, forming compressional mountain ranges and adding new material to continents ...
... trenches The oceanic crust is a thin layer on top of a convecting mantle Continents as rafts of lighter material -‘bump’ into each other, forming compressional mountain ranges and adding new material to continents ...
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.