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 27 for “"magma ocean"”.
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Mantle-Melting at High Pressure: Experimental Constraints on Magma Ocean Differentiation
… are relevant to the crystallisation of a deep magma ocean, that likely existed during Earth’s accretion. The melting relations of potential magma ocean compositions, such as peridotitic and chondritic bulk compositions, were investigated using multianvil apparatus at pressures of 25-26 GPa and …
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Terrestrial magma ocean solidification and formation of a candidate D" layer
… we investigate the solidification of early magma oceans on the Earth and the formation of a deep dense layer at the core-mantle boundary. We also study the concentrations and densities of the last layers of the solidified magma ocean and how they create a deep dense layer after solid-state …
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The Mercurian magma ocean, first crust, and implications for planetary formation mechanisms
… core, and by processing the mantle through a magma ocean, would produce a low-iron crust. More Earth-like bulk compositions require silicate removal, perhaps by a giant impact, to create the planet's large core fraction. The earliest crusts expected in a giant impact scenario are discussed in …
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Carbon in Silicate Melt - Experimental Constraints and Applications for the Subduction Zone and Magma Ocean Carbon Cycles
… to constrain the carbon content of early Earth’s magma ocean. Combining our experiments with previous work, we developed an empirical model that describes the dissolved CO2 content as a function of pressure, temperature, H2O content, oxygen fugacity, and silicate composition. This model was …
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Experimental simulation of Lunar Magma Ocean crystallization : insights into mantle composition and the source regions of lunar basaltic magmatism
Crystallization of the Lunar Magma Ocean has been empirically modeled and its products inferred from sample observations, but it has never been fully tested experimentally. Presented in this study is the first experimental simulation of lunar differentiation. Two end-member bulk Moon compositions …
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Hydrocode modeling of oblique impacts into terrestrial planets
… and undergo turbulent entrainment in a global magma ocean; under these conditions, cores greater than 10 km in diameter do not fully mix without a sufficiently deep magma ocean. I have performed hydrocode simulations that revise this assumption and yield a clearer picture of the impact process …
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Primitive magmas of the Earth and Moon : a petrologic investigation of magma genesis and evolution
… that the Commondale Komatiites were hydrous magmas when they were emplaced. Hydrous komatiites provide evidence for the existence of subduction zone volcanism during the Archean, and decreases the temperature required to explain komatiites volcanism, which is the major physical evidence used …
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Quantifying melting and chemical differentiation processes on Earth and the Moon
… under which the Earth could have crystallized a magma ocean that then overturned and remixed to form an Early Enriched Reservoir and a complementary Early Depleted Reservoir consistent with isotopic measurements of Archean rocks. This study found that Earth most likely last differentiated a …
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Petrological and rheological controls on volcanism to terrestrial planets
… 2), gravitational instabilities in the lunar magma ocean cumulates (Chapter 7), and thinning and convection due to giant meteorite impacts (Chapters 3 and 8), has lead to new models for melt production. These studies together show how lithospheric thinning and unusual mantle compositions can …
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First principles phase diagram calculations in group IV carbides and Mg2SiO4 liquid from Molecular Dynamics
… early history of our planet, when it was in a magma ocean stage. Due to high melting temperatures little is known experimentally about its high pressure thermodynamic and transport properties that govern magma ocean structure and dynamics. Molecular dynamics simulations now fill this gap. …
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An experimental and petrologic investigation of the source regions of lunar magmatism in the context of the primordial differentiation of the Moon
… differentiation of the Moon via a global magma ocean has become the paradigm under which all lunar data are interpreted. The success of this model in explaining multiple geochemical, petrologic, and isotopic characteristics lunar geology has led to magma oceans becoming the preferred model …
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The Influence of Variable Oxygen Fugacity on the Source Depths for Lunar High-Titanium Ultramafic Glasses
… occurrence of a late-stage overturn of the lunar magma ocean, and we suggest that the source region of the high-titanium ultramafic magmas is more oxidizing than previously assumed. More oxidized source region conditions are necessary for these magmas to be buoyant relative to their surrounding …
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The influence of core crystallization and mantle overturn on ancient dynamos
… of the Martian mantle. The solidification of a magma ocean may result in an unstable density profile prone to overturn. A long-wavelength instability could play a role in the stark contrasts observed between the northern and southern hemispheres of Mars, including the dichotomy in crustal …
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Experimental studies of magmatic differentiation and the effects of water on phase stability
… crystallization affect the chemical evolution of magmas. A major focus is the effect of water on the stability of mineral phases, and how this affects both the differentiation of magmas and the modification of the upper mantle by hydrous fluid release during subduction. Chapter 1 models the …
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Metal-silicate Partitioning Behavior of Molybdenum, Tungsten, and Nickel: Implications for Core Formation
… of these elements were set by a global magma ocean near the end of accretion with conditions of 35-37 GPa (~1100 km depth) and 2950-3000 K with XC = 0.07, XS = 0.05, and XSi = 0.06. Thus implying that large impacts in the late stages of Earth's accretion were energetic enough to …
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A dynamo case study of Mercury, and the early orbital and thermal evolution of the Moon
… We couple the orbital evolution with lunar magma ocean solidification to assess the mutual effects of orbital processes and the Moon's thermal profile on each other. We find that the resonance is unstable for causing severe tidal heating in the Moon, while the limit cycle works with …
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The effect of bombardment of small bodies on the evolution of atmospheres of terrestrial bodies
… simple model for the simultaneous evolution of a magma ocean and atmosphere on a terrestrial planet. The results of this dissertation are summarised in Chapter 7.
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Kinetics of chemical exchange during melting of planetary interiors
… system at conditions typical of melting beneath ocean spreading centers, leading to less efficient fractionation of the rare earth elements than under conditions of local chemical equilibrium. Chapter 4 presents experiments on the diffusion of U and Th in diopside at I atm pressure. Uranium and …
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Experimental constraints on the thermodynamic modelling of siderophile element distribution during core-segregation and basalt petrogenesis
… single-stage equilibration at the base of a magma ocean. Fe K-edge XANES spectra of trivalent Fe bearing glasses indicate an increase in average coordination state between 0.55 and 4 GPa while W L{u2083}-edge spectra of hexavalent W bearing glasses indicate a tetrahedral environment over all …
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Experimental constraints on the thermodynamic modelling of siderophile element distribution during core-segregation and basalt petrogenesis
… single-stage equilibration at the base of a magma ocean. Fe K-edge XANES spectra of trivalent Fe bearing glasses indicate an increase in average coordination state between 0.55 and 4 GPa while W L{u2083}-edge spectra of hexavalent W bearing glasses indicate a tetrahedral environment over all …
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