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 20 of 58 for “"crustal thickness"”.
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Using Crustal Thickness Modeling to study Mars' Crustal and Mantle Structures
Mars has an intriguing topographic and crustal dichotomy that divides the planet into a Northern Hemisphere and a Southern Hemisphere. The biggest question is to understand how this dichotomy was formed and what are the implications to the interior evolution of the planet. This study uses …
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The origin of the assymetry in the Iceland hotspot along the Mid-Atlantic ridge from continental breakup to present-day
… with the evolving ridge system. Modeled maps of crustal thickness and plume influence indicate that asymmetrical influence along the ridge system is partially caused by the asymmetric ridge configuration relative to the hotspot center, and is either enhanced by variations thermal lithosphere …
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The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling
Segmentation and crustal accretion at oceanic transform fault systems are investigated through a combination of geophysical data analysis and geodynamical and geochemical modeling. Chapter 1 examines the effect of fault segmentation on the maximum predicted earthquake magnitude of an oceanic …
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The dynamics of oceanic transform faults : constraints from geophysical, geochemical, and geodynamical modeling
Segmentation and crustal accretion at oceanic transform fault systems are investigated through a combination of geophysical data analysis and geodynamical and geochemical modeling. Chapter 1 examines the effect of fault segmentation on the maximum predicted earthquake magnitude of an oceanic …
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The influence of magma supply and eruptive processes on axial morphology, crustal construction and magma chambers
… and eruptive processes on axial morphology, crustal construction, and the properties of crustal magma chambers at intermediate and fast spreading ridges. Variations in magma supply on time scales of ~100 Kyr generate along-axis changes in crustal thickness and temperature. Magma sill …
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Heat flow and tectonics of the Ligurian Sea basin and margins
Heat flow, tectonic subsidence and crustal thickness distributions in the Ligurian Basin are best explained by asymmetric lithospheric thinning mechanisms. Over 150 heat flow measurements are made on several transects between Nice, France and Calvi, Corsica on continental slope and rise settings. …
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THE SEDIMENT AND CRUSTAL STRUCTURE OF THE SOUTHEASTERN UNITED STATES
… I implement a method for constraining average crustal thickness and seismic velocities while correcting for the effects of sediments. I then use high-frequency constraints on sediment structure to construct a reference velocity model for the Atlantic Coastal Plain, discussing its implications …
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Receiver function studies of crustal structure, composition, and evolution beneath the Afar Depression, Ethiopia
… Geophysics group at Missouri S&T to characterize crustal properties beneath the Afar Depression in Ethiopia where extensional tectonics dominates. In this study, measurements of crustal thickness (H), crustal mean Vp/Vs [which is related to Poisson's ratio (Σ)], and the sharpness of the Moho (R) …
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The Significance of Densely Sampled Observations of Mantle Dynamic Topography
… by correcting for sedimentary loading and crustal thickness variation. Methodological improvements are implemented for both sedimentary and crustal corrections. Residual depth measurements typically deviate by $\pm$1~km from the predicted plate cooling trend. Positive and negative anomalies …
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Lithospheric Structure Across the Northern Canadian Cordillera from Teleseismic Receiver Functions
… estimates of the depth of the Moho and therefore crustal thickness under a broadband station. In this research we are interested in the structure of the crust and mantle across the northern Canadian cordillera, described by various tectonic settings. The teleseismic data recorded by broadband …
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Tomographic inversion of Pn travel times in western China
… study, we obtain a Pn velocity image and the crustal thickness for western China using a Pn tomographic inversion based on a large collection of Pn travel time data from various sources. Our tomography image reveals four significant features corresponding to the surface geology: (1) Four major …
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Tectonics of the West Iberia continental margin from seismic reflection data
… seafloor spreading. Two independent estimates of crustal thickness along this line indicate stretching factors of 50% on the proximal margin (corresponding to a continental crustal thickness of ∼16 km), increasing to 100% in the deep water. Plate tectonics is one of the most important concepts …
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EASTERN BASIN AND RANGE CRUSTAL EXTENSION: A VIEW FROM SEISMOLOGY AND GEODESY
This dissertation investigates the crustal structure of the eastern Basin and Range Province in the western United States and its relationship with the present-day extensional regime governing this region. The use of combined results from different geophysical methods provide a better understanding …
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The influence of ridge geometry at the ultraslow-spreading Southwest Indian Ridge (9⁰-25⁰E) : basalt composition sensitivity to variations in source and process
… (i.e. morphology, upwelling rate, lithospheric thickness), basalt chemistry, and crustal thickness (estimated from gravity) provides a unique opportunity to compare the influence of spreading geometry and rate on MORB generation. What had not been well established until now is the importance of …
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Crustal accretion and evolution at slow and ultra-slow spreading mid-ocean ridges
… variations in active ridge processes and crustal aging at slow-spreading centers by comparing axial crustal structure with that on conjugate flanks of the slow-spreading Mid-Atlantic Ridge (MAR) (full rate, 20 km/Myr) and the ultra-slow spreading Southwest Indian Ridge (SWIR) (full rate, …
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Geophysical insights into the histories of Venus, Mercury and the Moon
… Magellan mission. These ratios inform models of crustal thickness and mantle density, which in turn have implications for the formation of Venus's highland crust. I perform spatio-spectral localization of gravity and topography on Mercury from the MErcury Surface, Space ENvironment, GEochemistry, …
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Inferring the thermomechanical state of the lithosphere using geophysical and geochemical observables
… the lithosphere. In Chapter 1, I correlate lower crustal rheology with seismic wave speed. Compositional variation is required to explain half of the total variability in predicted lower crustal stress, implying that constraining regional lithology is important for lower crustal geodynamics. In …
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The evolution of lithospheric deformation and crustal structure from continental margins to oceanic spreading centers
… the evolution of lithospheric deformation and crustal structure from continental margins to mid-ocean ridges. The first part (Ch. 2) examines the style of segmentation along the U.S. East Coast Margin and investigates the relationship between incipient margin structure and segmentation at the …
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Inferring the Thermomechanical State of the Lithosphere Using Geophysical and Geochemical Observables
… the lithosphere. In Chapter 1, I correlate lower crustal rheology with seismic wave speed. Compositional variation is required to explain half of the total variability in predicted lower crustal stress, implying that constraining regional lithology is important for lower crustal geodynamics. In …
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A geologic and potential field investigation of the central Virginia Piedmont
… of the Piedmont gravity high is a result of both crustal thickness variation and density contrasts between the surficially exposed lithologies. Geologic, gravity and magnetic field modeling has determined the structure of the antiform and the Triassic basin to a depth of 5 km. Microearthquake …
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