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 25 for “"mantle plumes"”.
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Dynamics of mantle plumes
Mantle plumes are a link between different scales in the Earth’s mantle: They are an important part of large-scale mantle convection, transporting material and heat from the core-mantle boundary to the surface, but also affect processes on a smaller scale, such as melt generation and transport and …
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Wavefront Healing and Tomographic Resolution of Mantle Plumes
To investigate seismic resolution of deep mantle plumes as well as the robustness of the anti-correlation between bulk sound speed and S wave speed imaged in the lowermost mantle, we use a Spectral Element Method (SEM) to simulate global seismic wave propagation in 3-D wavespeed models and measure …
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Interactions between mantle plumes and mid-ocean ridges : constraints from geophysics, geochemistry, and geodynamical modeling
… interactions between mid-ocean ridges and mantle plumes using geophysics, geochemistry, and geodynamical modeling. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow spreading, highly-segmented Southwest Indian Ridge (SWIR). Gravity data indicate that …
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Interactions between mantle plumes and mid-ocean ridges : constraints from geophysics, geochemistry, and geodynamical modeling
… interactions between mid-ocean ridges and mantle plumes using geophysics, geochemistry, and geodynamical modeling. Chapter 1 investigates the effects of the Marion and Bouvet hotspots on the ultra-slow spreading, highly-segmented Southwest Indian Ridge (SWIR). Gravity data indicate that …
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Origin of geochemical heterogeneity in the mantle : constraints from volcanism associated with Hawaiian and Kerguelen mantle plumes
Lavas derived from long-lived mantle plumes provide important information of mantle compositions and the processes that created the geochemical heterogeneity within the mantle. Kerguelen and Hawaii are two long-lived mantle plumes and lavas associated with them have very different geochemical …
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The Cretaceous to recent history of the southeastern Indian Ocean : the role of mantle plumes examined by geochronology and Sr, Nd, Pb and He isotopic geochemistry
… interactions between mid-ocean ridges and mantle plumes. Plateaus, ridges and islands associated with the Kerguelen hotspot, the world's second largest, oceanic igneous province, dominate the bathymetry of the southeastern Indian Ocean. Lavas erupted by the Kerguelen plume range in age from …
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Unravelling the Dynamical Mechanisms Underpinning Intra-Plate Volcanism Within and Around Earth's Continents
… grow older in the direction of plate motion, mantle plumes are the preferred driving mechanism for the initiation of mantle melting. Elsewhere, shallower convective instabilities, bound to significant changes in lithospheric thickness, have been gaining popularity in explaining the onset of …
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Unravelling the Dynamical Mechanisms Underpinning Intra-Plate Volcanism Within and Around Earth's Continents
… grow older in the direction of plate motion, mantle plumes are the preferred driving mechanism for the initiation of mantle melting. Elsewhere, shallower convective instabilities, bound to significant changes in lithospheric thickness, have been gaining popularity in explaining the onset of …
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The Structure and Behavior of Plate Boundary Regions Through the Wilson Cycle
… constraints on the extent of enriched mantle from upwelling mantle plumes relative to the observed extent of topographic swells related to mantle flow. It builds on this data by presenting a new geophysical model of mantle flow around mantle plumes that constrains the viscosity …
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The Evolution of the Galapagos Mantle Plume: From Large Igneous Province to Ocean Island Basalt
Mantle plumes are anomalously hot, narrow upwellings of mantle material that originate at the core-mantle boundary. As plumes rise they may form volumetrically large "heads" (~1000 km in diameter) with narrower (~100 km) "tails." Plume head melting is thought to form Large Igneous Provinces (LIPs), …
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Evaluating mantle and crustal processes using isotope geochemistry
… distinct reservoirs such as the Earth's crust, mantle and core. In this dissertation the strategy has been to work on a broad range of topics to evaluate crustal and mantle processes. This study presents Re-Os systematics to constrain the composition, formation and age of the lower continental …
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A broad Iceland plume associated with two phase transitions at the 660 km discontinuity: Constraints from receiver functions
… frequently regarded as the archetypal example of mantle plumes, the existence, depth extent, origin, dimension and excess temperature of the hypothesized plume remain enigmatic and hotly debated. The controversy mostly originates from the limited vertical resolution of seismic tomography …
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Geodynamic Modeling Applied to Venus
… pertaining to the dynamics of the convecting mantle and core, layers humans have never directly interacted with. While the insights gleaned from these models cannot be argued, it is important to ensure calculations are understood and behaving correctly according to known math and physics. Here …
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Seismic anisotropy and mantle flow beneath Africa and Arabia
… phenomena involve edge-driven small-scale mantle convection and the thermal or dynamic effects of one or more mantle plumes. In this study we use continental scale shear-wave splitting (SWS) measurements to provide additional constraints on the various models of rifting, uplifting, and …
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The X-discontinuity: Seismic signatures of a heterogeneous upper mantle
… large-scale changes in composition like the core-mantle boundary. Widely distributed previous seismic observations of localised reflectors in the upper mantle have been termed the X-discontinuity (X; 230-350 km depth) and allude to the widespread presence of chemical heterogeneity, but the exact …
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Evaluating mantle and crustal processes using isotope geochemistry
… distinct reservoirs such as the Earth's crust, mantle and core. In this dissertation the strategy has been to work on a broad range of topics to evaluate crustal and mantle processes. This study presents Re-Os systematics to constrain the composition, formation and age of the lower continental …
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Magmatism and dynamics of continental breakup in the presence of a mantle plume
This thesis studies the dynamics of mantle melting during continental breakups by geophysical, geochemical, and numerical analyses. The first part focuses on the mantle melting and crustal accretion processes during the formation of the Southeast Greenland margin, on the basis of deep-crustal …
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Understanding Non-Plume Related Intraplate Volcanism
… of intraplate volcanism are dominated by mantle plumes, but alternative explanations, such as adiabatic decompression triggered by lithospheric delamination, and edge driven convection (EDC), could be responsible for magmatism. This dissertation explores intraplate volcanic locations that …
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Magma genesis beneath active continental rifts
… with geophysical evidence for low-density mantle underlying both rifts, have traditionally been interpreted as evidence for anomalously hot mantle plumes actively rising from the deep mantle beneath both regions. However, in light of increasing evidence that these mantle structures may also …
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Visualizing and Understanding Tectonism and Volcanism on Earth and Other Terrestrial Bodies
… is concerned with plate tectonics and plate/mantle plume interactions. Plate tectonics describes the mainly horizontal motion of lithospheric plates over the asthenosphere. Lithosphere is created at ridges and consumed at subduction zones. In addition to the plate tectonic system, mantle …
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