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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 10 of 10 for “"mantle geochemistry"”.
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Mantle Heterogeneity Through Mid-Ocean Ridge Basalts
The chemical heterogeneity of Earth's upper mantle is often examined through mid-ocean ridge basalts (MORB), which contest the prevalent assumption of a well-mixed convecting mantle. This dissertation delves into studying mantle heterogeneity from a local to regional scale. Initially, petrological …
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A heavy stable isotope approach to tracing mantle source and process
The geochemistry of global mantle melts suggests that both mid-ocean ridge basalts (MORB) and ocean island basalts (OIB) sample lithological heterogeneities originating in both the upper and lower mantle, with recycled crustal material accounting for a significant part of this variability. …
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Inside-out diversity of rocky planets
… bare-minimum, dynamic topography due directly to mantle convection, by finding scaling laws of dynamic topography with convective parameters. For increasingly massive planets, topography almost disappears. Smaller ocean basins might suggest flooded worlds, all else equal. Yet large portions of a …
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Insights into the location, nature and influence of mantle heterogeneity in the Galápagos mantle plume
… of the Earth's, highly heterogeneous, convecting mantle. Our view of the Earth's mantle is, however, partially obscured by processes that influence mantle-derived melts as they transition through the lithosphere (e.g. mixing, assimilation). Nevertheless, via careful consideration of the magmatic …
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Mantle-Melting at High Pressure: Experimental Constraints on Magma Ocean Differentiation
… melt ratios. This shows that the Earth’s upper mantle Mg/Si ratio is unlikely to be derived from chondrites by MgPv fractionation. Partition coefficients of tri- and tetravalent elements increase with increasing Al concentration of MgPv. A crystal chemical model indicates that Al3+ substitutes …
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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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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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Mantle melting processes: evidences from ophiolites, large igneous provinces, and intraplate seamounts
Melting processes in the mantle have a key role in plate tectonics and in the most colossal phenomena in the Earth, like large igneous provinces, mantle plume upwellings, and the constant growth of the planet's tectonic plates. In this study we use the geochemical and petrological evidence …
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Geochemical Implications of Stirring and Mixing in the Earth's Mantle
… state convection that occurs in the Earth's mantle, but to do so requires suitable quantitative models. A new statistical model is introduced to better understand the observed heterogeneity in isotopic ratios 143Nd/144Nd, 87Sr/86Sr, 176Hf/177Hf,208Pb/204Pb, 206Pb/204Pb and 207Pb/204Pb …
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Edelgase als Tracer für Wechselwirkungen von Krusten- und Mantelfluiden mit diamantführenden Gesteinen des östlichen Baltischen Schildes
In der vorliegenden Arbeit werden anhand der Edelgaszusammensetzung von Kimberliten und Lamproiten sowie ihrer gesteinsbildenden Minerale die Wechselwirkungen dieser Gesteine mit Fluiden diskutiert. Die untersuchten Proben stammen vom östlichen Baltischen Schild, vom Kola-Kraton (Poria Guba und …