Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 16 of 16 for “"mantle temperature"”.
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Lateral variation in upper mantle temperature and composition beneath mid-ocean ridges inferred from shear-wave propagation, geoid, and bathymetry
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
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Probing the Mantle Transition Zone beneath the Central Pacific Region Using PP Precursors
The mantle transition zone (MTZ) of the Earth is bounded by globally observed discontinuities at depths of about 410 and 660 km, which are mainly attributed to the spinel and post-spinel phase transitions of olivine. The temperature-pressure relationships of phase transitions at the …
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The influence of magma supply and eruptive processes on axial morphology, crustal construction and magma chambers
… at mid-ocean ridges where magmas rise from the mantle and cool to form the oceanic crust. The objective of this Thesis is to examine the influence of magma supply and eruptive processes on axial morphology, crustal construction, and the properties of crustal magma chambers at intermediate and …
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Global Relationships Between Intraplate Magmatism and Dynamic Topography
… and viscous flow within the convecting mantle generate deflections of the Earth’s surface with amplitudes of ±1 km and wavelengths of ~1000 km. Geoidal, shear-wave velocity, and oceanic residual depth anomalies allow present-day dynamic topography to be estimated. However, the mantle …
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Discipline-Based Planetary Education Research and Computational Fluid Dynamics Analysis of Mars
… A 2-D finite element convection model for the mantle of Mars was designed and solved using COMSOL Multiphysics 5.1, to investigate whether or not thermal gradients in a Mars-sized planet could cause vigorous upper mantle convection, consistent with plate tectonic processes. Results from this …
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Mantle plume-midocean ridge interaction : geophysical observations and mantle dynamics
… plume-ridge systems to constrain crustal and mantle density structure at these prominent oceanic features. Numerical models are then used to explore the physical mechanisms controlling plume-ridge interaction and to place theoretical constraints on the temperature anomalies, dimensions, and …
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Formation and evolution of the eastern Black Sea basin: constraints from wide-angle seismic data
… structure of the deep sediments, crust and upper mantle within the EBS basin. These data provide a unique look at the formation of extensional basins, as the dataset includes a profile that is orientated parallel to the rift axis. This profile places new constraints on the variation in magmatism …
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Understanding Mercury's Thermochemical Evolution Using a Geochemical and Geophysical Lens
… a melt formed in a relatively thin, FeO poor mantle, and a large metal rich core made from Fe and some quantity of a light element. These conditions are different than those seen on Earth: a thick crust covered by a layer of varied thickness made up of loose unconsolidated rocks and dust, a …
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Basalt petrogenesis beneath slow- and ultraslow-spreading Arctic mid-ocean ridges
… To use U-series isotopes to further constrain mantle heterogeneity and the timing and nature of melting and melt transport processes, U-Th-Pa-Ra disequilibria, radiogenic isotopes, and trace-element compositions were measured for the slow-spreading Arctic mid-ocean ridges (MOR). A focused case …
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Teleseismic P Wave Attenuation in the Upper Mantle Beneath the United States
… seismic attenuation patterns in the upper mantle. 2.5 million inter-station P wave spectral ratios were inverted for maps of relative t* variations across the United States in multiple frequency bands between 0.08 and 2 Hz. Broader frequency bands are associated with lower magnitude …
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Continental Magmatism and Dynamic Topography
… slow seismic velocity anomalies within the upper mantle. Volcanic activity and elevated heat flow are also often observed. The aim of this study is to investigate the link between geochemical compositions of intracontinental magmatism and geophysical, geomorphological and geodetic observations of …
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Basalt Magmatism as a Key to Unlocking Cenozoic Dynamic Topography
Reconstructing mantle dynamic topography through space and time remains a significant challenge. Nevertheless, useful insights can be gained by analysing Cenozoic basalt magmatism, which correlate with convectively driven regional uplift across the globe. This dissertation comprises three regional …
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Seismic imaging of the mantle transition zone
… high-resolution seismo-stratigraphy of the upper mantle transition zone. The generalized Radon transform (GRT) is based on the single scattering approximation and maps singularities (reflections) in broad-band data into singularities (reflectors/scatters) in the medium. It is able to detect and …
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Spatial-Statistical Properties of Geochemical Variability as Constraints on Magma Transport and Evolution Processes at Ocean Ridges
… major element variability in basaltic lavas and mantle residues to constrain some of the processes and dynamics occurring beneath ocean ridge magmatic systems. Ocean ridges represent a critical setting for many geochemical fractionation processes involved in the chemical evolution of the silicate …
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The isotope geochemistry of abyssal peridotites and related rocks
… aspects of the formation of the Earth's oceanic mantle and crust, using a variety of geologic techniques, principally major elements, radiogenic isotopes and trace elements, but including petrography, mineral chemistry, x-ray diffraction, seafloor geomorphology, and analysis of the tectonics of …
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Deep Earth volatile cycles as revealed by basalt chemistry
… is our most direct probe of Earth’s convecting mantle, however the tendency of volatile elements to form vapour phases deep within volcanic systems obscures the mantle volatile signals inherited by basalts. This thesis explores the extent to which basalts may preserve mantle volatile signals, …