Geophysical Constraints on Mantle Composition
... Mathematical inversion of large numbers of travel times, observed at a variety of distances between source (earthquake) and receiver (seismometer), results in velocity profiles that represent the variation of VP and VS (or Vj) as functions of depth. The changes in velocities across seismic ‘disconti ...
... Mathematical inversion of large numbers of travel times, observed at a variety of distances between source (earthquake) and receiver (seismometer), results in velocity profiles that represent the variation of VP and VS (or Vj) as functions of depth. The changes in velocities across seismic ‘disconti ...
Relations between sedimentary basins and petroleum
... represented as a single rotation around a fixed point). Specifically, by identifying the rotation pole of this relative motion, we can calculate the increase in linear velocity as distance from the pole increases (Fowler, 1990). However, in nature two plates may have a rotation pole which is not fix ...
... represented as a single rotation around a fixed point). Specifically, by identifying the rotation pole of this relative motion, we can calculate the increase in linear velocity as distance from the pole increases (Fowler, 1990). However, in nature two plates may have a rotation pole which is not fix ...
The Farallon-Aluk ridge collision with South America: Implications
... active plates transform margins, it can be stated that once the collision of a divergent ridge enables the coupling of the divergent ocean-floor to the continental crust through a transform fault, then the subducted plate detaches (or unzips), leaving a slab window behind. This new situation should r ...
... active plates transform margins, it can be stated that once the collision of a divergent ridge enables the coupling of the divergent ocean-floor to the continental crust through a transform fault, then the subducted plate detaches (or unzips), leaving a slab window behind. This new situation should r ...
Zha, Y., S. C. Webb, S. S. Wei, D. A. Wiens, D. K. Blackman, W
... We obtain phase velocity dispersion curves along 1225 interstation paths between the 50 OBS stations. For each frequency, only station pairs with distances longer than twice the wavelength are included, and dispersion curves with physically unacceptable velocity values and step-like jumps are discar ...
... We obtain phase velocity dispersion curves along 1225 interstation paths between the 50 OBS stations. For each frequency, only station pairs with distances longer than twice the wavelength are included, and dispersion curves with physically unacceptable velocity values and step-like jumps are discar ...
Subduction - Géosciences Montpellier
... allows nearly all oceanic lithosphere to be recycled into the mantle. By contrast, only the lower portion of the continental lithosphere (the lithospheric mantle) may, under certain conditions, be transported into the deep mantle. Since the continental crust resists subduction at depths beyond about ...
... allows nearly all oceanic lithosphere to be recycled into the mantle. By contrast, only the lower portion of the continental lithosphere (the lithospheric mantle) may, under certain conditions, be transported into the deep mantle. Since the continental crust resists subduction at depths beyond about ...
Fig. 1
... is an ideal natural laboratory to address this problem since the region exposes subaerially the tectonically active transition from continental rifting to incipient seafloor spreading. We review recent constraints on along-axis variations in rift morphology, crustal and mantle structure, the distribu ...
... is an ideal natural laboratory to address this problem since the region exposes subaerially the tectonically active transition from continental rifting to incipient seafloor spreading. We review recent constraints on along-axis variations in rift morphology, crustal and mantle structure, the distribu ...
Crust recycling in the sources of two parallel volcanic chains in
... obscured and recycled crustal sources are difficult to distinguish from crustal contamination. We show major, trace element and Sr–Nd–Hf isotopic compositions for two parallel chains of Cenozoic volcanoes from Shandong Province, North China, which are free of crustal contamination and show clear evid ...
... obscured and recycled crustal sources are difficult to distinguish from crustal contamination. We show major, trace element and Sr–Nd–Hf isotopic compositions for two parallel chains of Cenozoic volcanoes from Shandong Province, North China, which are free of crustal contamination and show clear evid ...
pdf version - Berkeley Seismological Laboratory
... observations [Chen, 1992; Dick et al., 2003; White et al., 1992]. The volume of oceanic crust is then calculated by multiplying the thickness of oceanic crust by the area of the seafloor at a given age, with the age of the seafloor determined from magnetic anomalies on the seafloor [M€ uller et al., 19 ...
... observations [Chen, 1992; Dick et al., 2003; White et al., 1992]. The volume of oceanic crust is then calculated by multiplying the thickness of oceanic crust by the area of the seafloor at a given age, with the age of the seafloor determined from magnetic anomalies on the seafloor [M€ uller et al., 19 ...
Chapter 7. Radiogenic Isotope Geochemistry of the Crust and Oceans
... As we found in Chapter 5, 182Hf (half-life 9 Ma) was present in the early Solar System and the silicate Earth’s 182W/184W is about 2 epsilon units higher than chondrites. The difference reflects sequestration of W in the Earth’s core (or, more likely, the cores of the planetary embryos that accreted ...
... As we found in Chapter 5, 182Hf (half-life 9 Ma) was present in the early Solar System and the silicate Earth’s 182W/184W is about 2 epsilon units higher than chondrites. The difference reflects sequestration of W in the Earth’s core (or, more likely, the cores of the planetary embryos that accreted ...
Thermal evolution of the Earth as recorded by komatiites
... and less frequently in the Phanerozoic. These magmas provide a record of the thermal and chemical characteristics of the upper mantle through time. The most widely cited interpretation is that komatiites were produced in a plume environment and record high mantle temperatures and deep melting pressu ...
... and less frequently in the Phanerozoic. These magmas provide a record of the thermal and chemical characteristics of the upper mantle through time. The most widely cited interpretation is that komatiites were produced in a plume environment and record high mantle temperatures and deep melting pressu ...
Crustal flow in Tibet: geophysical evidence for the physical state of
... corridor across the plateau (this transect will continue in 2007 as INDEPTH-4 across the northern boundary of Tibet). Without minimizing the contributions of many other groups, these three international programs collected data that continue to be re-analyzed today, a decade or more after acquisition ...
... corridor across the plateau (this transect will continue in 2007 as INDEPTH-4 across the northern boundary of Tibet). Without minimizing the contributions of many other groups, these three international programs collected data that continue to be re-analyzed today, a decade or more after acquisition ...
The American Cordillera: Part III, The North American Taphrogen
... under the Colorado Plateau. This is the time period in which the SW Arizona and Mexican core complexes was active. The intact lithosphere left behind protected the CP from rollback extension and magmatism that affected the rest of the western US. The pink areas represent new asthenosphere that flowe ...
... under the Colorado Plateau. This is the time period in which the SW Arizona and Mexican core complexes was active. The intact lithosphere left behind protected the CP from rollback extension and magmatism that affected the rest of the western US. The pink areas represent new asthenosphere that flowe ...
The Proterozoic Part 1 - University of South Alabama
... Other Proterozoic Orogenies Orogeny: A mountain building event (mostly collision and subduction, occasionally transform motion, but doesn’t require continent-continent collisions) Note: Most mountain building episodes (regardless of the actual process are given specific names) e.g.: the Wopmay Orog ...
... Other Proterozoic Orogenies Orogeny: A mountain building event (mostly collision and subduction, occasionally transform motion, but doesn’t require continent-continent collisions) Note: Most mountain building episodes (regardless of the actual process are given specific names) e.g.: the Wopmay Orog ...
Geophysical-petrological model of the crust and upper mantle in the
... The India-Eurasia collision zone consists of a large amalgamation of crustal and lithospheric domains, accreted each other throughout time. The India peninsula is formed by an ancient continental crust (the Precambrian Indian shield), which is itself a collage of cratonic blocks and mobile belts ass ...
... The India-Eurasia collision zone consists of a large amalgamation of crustal and lithospheric domains, accreted each other throughout time. The India peninsula is formed by an ancient continental crust (the Precambrian Indian shield), which is itself a collage of cratonic blocks and mobile belts ass ...
Mountain Building Processes in Four-Dimensions (4D-MB)
... Seismicity in the Alpine region is characterized by diffuse, shallow seismicity that only partly reflects AdriaEurope convergence and does not necessarily follow geologically mapped faults. Whereas the domain of highest Adria-Europe convergence at the Alps-Dinarides junction indeed correlates with h ...
... Seismicity in the Alpine region is characterized by diffuse, shallow seismicity that only partly reflects AdriaEurope convergence and does not necessarily follow geologically mapped faults. Whereas the domain of highest Adria-Europe convergence at the Alps-Dinarides junction indeed correlates with h ...
The evolving nature of terrestrial crust from the Hadean, through the
... of 3.60–3.75 Ga old. Earlier attempts at finding very ancient rocks had unearthed Neoarchaean rocks in a variety of places, for example in the Lewisian of northern Scotland (e.g. Giletti, 1959; Evans, 1965) while Pb-isotope studies (e.g. Kanasewich and Farquhar, 1965) had indirectly hinted at the exi ...
... of 3.60–3.75 Ga old. Earlier attempts at finding very ancient rocks had unearthed Neoarchaean rocks in a variety of places, for example in the Lewisian of northern Scotland (e.g. Giletti, 1959; Evans, 1965) while Pb-isotope studies (e.g. Kanasewich and Farquhar, 1965) had indirectly hinted at the exi ...
Melting Relations of MORB^Sediment Me
... are produced within the continental crust. Currently accepted intra-crustal models include: (1) assimilation of continental crustal rocks by basalt magmas (e.g. De Paolo, 1981; Patin‹o-Douce, 1995); (2) coupled magma mixing and crustal assimilation, involving hydrous basalts and continental crustal ...
... are produced within the continental crust. Currently accepted intra-crustal models include: (1) assimilation of continental crustal rocks by basalt magmas (e.g. De Paolo, 1981; Patin‹o-Douce, 1995); (2) coupled magma mixing and crustal assimilation, involving hydrous basalts and continental crustal ...
PDF
... with the Ontong Java Plateau is the best example of this mode. Spontaneous nucleation (SNSZ) results from gravitational instability of oceanic lithosphere and is required to begin the modern regime of plate tectonics. Lithospheric collapse initiates SNSZ, either at a passive margin or at a transform ...
... with the Ontong Java Plateau is the best example of this mode. Spontaneous nucleation (SNSZ) results from gravitational instability of oceanic lithosphere and is required to begin the modern regime of plate tectonics. Lithospheric collapse initiates SNSZ, either at a passive margin or at a transform ...
Softening of the subcontinental lithospheric mantle by
... Figs. 3 and 4 show vertical temperature profiles in the lithosphere in correspondence of the centre of the ALM, as a function of thickness of impregnated volume at t = 250 ka after the beginning of cooling (Fig. 3) and as a function of time if the whole lithospheric mantle is affected (Fig. 4). In b ...
... Figs. 3 and 4 show vertical temperature profiles in the lithosphere in correspondence of the centre of the ALM, as a function of thickness of impregnated volume at t = 250 ka after the beginning of cooling (Fig. 3) and as a function of time if the whole lithospheric mantle is affected (Fig. 4). In b ...
Phase Transitions and Mineralogy of the Upper Mantle
... xenoliths incorporated in volcanic rocks erupted on the Earth’s surface. Such mantle xenoliths are common in certain alkali-rich mafic magmas and kimberlites. Field evidence suggests that the upper mantle is peridotitic in composition, although significant heterogeneities are clearly recognized. Fro ...
... xenoliths incorporated in volcanic rocks erupted on the Earth’s surface. Such mantle xenoliths are common in certain alkali-rich mafic magmas and kimberlites. Field evidence suggests that the upper mantle is peridotitic in composition, although significant heterogeneities are clearly recognized. Fro ...
Earthquakes - Kean University
... enforced a stringent building code over the last 30 years that requires new structures to be able to withstand large earthquakes. In addition, over the last decade, many older buildings and bridges were retrofitted to ensure that they could endure the big earthquake predicted for the region. Residen ...
... enforced a stringent building code over the last 30 years that requires new structures to be able to withstand large earthquakes. In addition, over the last decade, many older buildings and bridges were retrofitted to ensure that they could endure the big earthquake predicted for the region. Residen ...
Plate Tectonics
... • Identical rocks, of the same type and age, are found on both sides of the Atlantic Ocean. Wegener said the rocks had formed side by side and that the land had since moved apart. • Mountain ranges with the same rock types, structures, and ages are now on opposite sides of the Atlantic Ocean. The Ap ...
... • Identical rocks, of the same type and age, are found on both sides of the Atlantic Ocean. Wegener said the rocks had formed side by side and that the land had since moved apart. • Mountain ranges with the same rock types, structures, and ages are now on opposite sides of the Atlantic Ocean. The Ap ...
Mantle structure and tectonic history of SE Asia
... Fig. 2. Tomographic slices through model UU-P07 (Amaru, 2007) at selected depths. Colours indicate the P-wave wave-speed anomalies relative to the radial reference model ak135 of Kennett et al. (1995). Notice that the limits of the wave-speed anomaly scale change with depth. This depth variation fol ...
... Fig. 2. Tomographic slices through model UU-P07 (Amaru, 2007) at selected depths. Colours indicate the P-wave wave-speed anomalies relative to the radial reference model ak135 of Kennett et al. (1995). Notice that the limits of the wave-speed anomaly scale change with depth. This depth variation fol ...
2.03 Sampling Mantle Heterogeneity through Oceanic Basalts
... that chemical disequilibrium between grain centers and margins will persist during melting. Consequently, the melt will not be in equilibrium with the bulk residue for geologically reasonable melting times, if the equilibration occurs by volume diffusion alone. This means that the conclusions of Hof ...
... that chemical disequilibrium between grain centers and margins will persist during melting. Consequently, the melt will not be in equilibrium with the bulk residue for geologically reasonable melting times, if the equilibration occurs by volume diffusion alone. This means that the conclusions of Hof ...
Post-glacial rebound
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Post-glacial rebound (sometimes called continental rebound) is the rise of land masses that were depressed by the huge weight of ice sheets during the last glacial period, through a process known as isostatic depression. Post-glacial rebound and isostatic depression are different parts of a process known as either glacial isostasy, glacial isostatic adjustment, or glacioisostasy. Glacioisostasy is the solid Earth deformation associated with changes in ice mass distribution. The most obvious and direct affects of post-glacial rebound are readily apparent in northern Europe (especially Scotland, Estonia, Latvia, Fennoscandia, and northern Denmark), Siberia, Canada, the Great Lakes of Canada and the United States, the coastal region of the US state of Maine, parts of Patagonia, and Antarctica. However, through processes known as ocean siphoning and continental levering, the effects of post-glacial rebound on sea-level are felt globally far from the locations of current and former ice sheets.