Isostasy, dynamic topography, and the elevation of the Apennines of
... calculate flow velocities form density anomalies based on different seismic tomography models. Topography estimates are then compared with geodetic and geological data to infer uplift and subsidence histories. The result of this comparative analysis is used to quantify the relative contribution of is ...
... calculate flow velocities form density anomalies based on different seismic tomography models. Topography estimates are then compared with geodetic and geological data to infer uplift and subsidence histories. The result of this comparative analysis is used to quantify the relative contribution of is ...
American Journal of Science - gemoc
... categories. First are those related to cooling of the mantle and include a decrease in both komatiite abundance and MgO content, a decrease in Ni/Fe ratio in banded iron formation, and increases in incompatible element ratios (such as Nb/Yb, La/Yb, Zr/Y, La/Sm and Gd/Yb) in non-arc type basalts. A s ...
... categories. First are those related to cooling of the mantle and include a decrease in both komatiite abundance and MgO content, a decrease in Ni/Fe ratio in banded iron formation, and increases in incompatible element ratios (such as Nb/Yb, La/Yb, Zr/Y, La/Sm and Gd/Yb) in non-arc type basalts. A s ...
The Earth`s mantle
... of former lithospheric material. Global seismic tomographic images, based on both short- and long-period data, also strongly suggest slab penetration into the lower mantle. A variety of modern studies show narrow features of high seismic velocity extending from sites of present-day subduction deep i ...
... of former lithospheric material. Global seismic tomographic images, based on both short- and long-period data, also strongly suggest slab penetration into the lower mantle. A variety of modern studies show narrow features of high seismic velocity extending from sites of present-day subduction deep i ...
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... MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Ocean crust is generally lower in elevation ________. A) averaging about 380 metres below sea level B) entirely because of the great weight of the overlying sea water C) and contains prominent r ...
... MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) Ocean crust is generally lower in elevation ________. A) averaging about 380 metres below sea level B) entirely because of the great weight of the overlying sea water C) and contains prominent r ...
Seismic response and anisotropy of a model hcp iron inner core
... The global inner core anisotropy is 7 times smaller than that of the single crystal. Compositional stratification amplifies the global anisotropy by 15% while the addition of solidification textures reduces it by a factor of 2. As such, and within the tested geodynamical models, no published elastic ...
... The global inner core anisotropy is 7 times smaller than that of the single crystal. Compositional stratification amplifies the global anisotropy by 15% while the addition of solidification textures reduces it by a factor of 2. As such, and within the tested geodynamical models, no published elastic ...
Subduction zones: observations and
... ities, both of which are characteristics of subduction zones that we would like to be able to model (Weinstein and Christensen, 1991). While the structure of the top thermal boundary layer might seem somewhat removed from the issue of subduction, it is really quite important. In stagnant- and sluggi ...
... ities, both of which are characteristics of subduction zones that we would like to be able to model (Weinstein and Christensen, 1991). While the structure of the top thermal boundary layer might seem somewhat removed from the issue of subduction, it is really quite important. In stagnant- and sluggi ...
Thermal evolution of the Earth as recorded by komatiites
... overlap of boninites with basaltic komatiites interlayered with the komatiites (Fig. 1). The plume advocates dismiss the high-SiO2 compositions as formed by either fractionation or crustal contamination of komatiite magmas, while subduction advocates question whether Gorgona magmas should be conside ...
... overlap of boninites with basaltic komatiites interlayered with the komatiites (Fig. 1). The plume advocates dismiss the high-SiO2 compositions as formed by either fractionation or crustal contamination of komatiite magmas, while subduction advocates question whether Gorgona magmas should be conside ...
Large-Scale Thermo-chemical Structure of the Deep Mantle
... models (Ritsema et al. 2011) suggest that it may split into a western and an eastern province with a gap of several hundreds of kilometers in between. Both provinces have a trapezoidal shape, but the western region has stronger topography than the eastern region. Sharp boundaries at the southern ed ...
... models (Ritsema et al. 2011) suggest that it may split into a western and an eastern province with a gap of several hundreds of kilometers in between. Both provinces have a trapezoidal shape, but the western region has stronger topography than the eastern region. Sharp boundaries at the southern ed ...
Propagating rift model for the V‐shaped ridges south of Iceland
... that show that seafloor spreading has not occurred symmetrically about a stable Reykjanes Ridge axis, and that the VSR pattern is not symmetric about the axis. The data are consistent with a sequence of new Reykjanes Ridge axes propagating south away from Iceland, usually but not always transferring ...
... that show that seafloor spreading has not occurred symmetrically about a stable Reykjanes Ridge axis, and that the VSR pattern is not symmetric about the axis. The data are consistent with a sequence of new Reykjanes Ridge axes propagating south away from Iceland, usually but not always transferring ...
Recycled crust in the Galápagos Plume source at 70 Ma
... Our goal is to use high precision olivine data to infer the lithology of the source that melted to produce the Quepos picrites; additionally, we examine olivines from the older CLIP lavas from Curacao in order to provide constraints on how the source lithology changed from ∼90 to 70 Ma. A detailed d ...
... Our goal is to use high precision olivine data to infer the lithology of the source that melted to produce the Quepos picrites; additionally, we examine olivines from the older CLIP lavas from Curacao in order to provide constraints on how the source lithology changed from ∼90 to 70 Ma. A detailed d ...
Asymmetry of high-velocity lower crust on the South
... et al., 2008), but they have not yet been studied for areal extent and rifting process determination. That is the purpose of the study reported here. We provide seismic velocity and gravity models for two new margin profiles in South America and integrate them with five others into a regional interp ...
... et al., 2008), but they have not yet been studied for areal extent and rifting process determination. That is the purpose of the study reported here. We provide seismic velocity and gravity models for two new margin profiles in South America and integrate them with five others into a regional interp ...
A global-scale plate reorganization event at 105−100Ma
... A major plate reorganization is postulated to have occurred at approximately 100 Ma. However, this reorganization has received limited attention, despite being associated with the most prominent suite of fracture zone bends on the planet and many other geological events. We investigate tectonic even ...
... A major plate reorganization is postulated to have occurred at approximately 100 Ma. However, this reorganization has received limited attention, despite being associated with the most prominent suite of fracture zone bends on the planet and many other geological events. We investigate tectonic even ...
GEO144_mid_term_I_so..
... (1) 2 pts. Compared to the age of the Earth accepted as correct today, how did seventeenth and eighteenth century proponents of catastrophism envision the Earth's age? A) They believed Earth to be much older than current estimates. B) They believed Earth to be much younger than current estimates. C) ...
... (1) 2 pts. Compared to the age of the Earth accepted as correct today, how did seventeenth and eighteenth century proponents of catastrophism envision the Earth's age? A) They believed Earth to be much older than current estimates. B) They believed Earth to be much younger than current estimates. C) ...
History of geomagnetism
The history of geomagnetism is concerned with the history of the study of Earth's magnetic field. It encompasses the history of navigation using compasses, studies of the prehistoric magnetic field (archeomagnetism and paleomagnetism), and applications to plate tectonics.Magnetism has been known since prehistory, but knowledge of the Earth's field developed slowly. The horizontal direction of the Earth's field was first measured in the fourth century BC but the vertical direction was not measured until 1544 AD and the intensity was first measured in 1791. At first, compasses were thought to point towards locations in the heavens, then towards magnetic mountains. A modern experimental approach to understanding the Earth's field began with de Magnete, a book published by William Gilbert in 1600. His experiments with a magnetic model of the Earth convinced him that the Earth itself is a large magnet.