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 19 of 19 for “"igneous petrology"”.
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A new approach to mass balance modeling: applications to igneous petrology
… to investigate mass balance relationships in igneous systems. A chi square (x²) minimization technique is used to solve the set of linear equations. The x² technique is superior to R² techniques because it considers the analytical errors on measurement data. Singular Value Decomposition (SVD) …
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The isotope geochemistry of uranium: Igneous petrology, ore deposits, and groundwater contamination
This study applies high precision 238U/235U measurement techniques two three geologic settings: basalt differentiation, uranium ore genesis, and the remediation of a uranium-contaminated groundwater system. In the latter two cases, 238U/235U is used as a tracer of uranium reduction. 238U …
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Stratigraphy, igneous petrology and evolution of the Sinclair Group in southern South West Africa
The investigation of an area fringing the Namib Desert in southern South West Africa has led to the clarification of relationships between several geological units of the Late Precambrian Sinclair Group, and to the formulation of a petrogenetic scheme and geotectonic model of evolution. In the area …
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The geochemistry, mineralogy and igneous petrology of some fracture zone basalts from the southern Mid-Atlantic Ridge
The compositional variation in a suite of oceanic basalts dredged from a fracture zone transecting the Mid-Atlantic Ridge at 54°S is quantitatively evaluated in terms of fractional crystallization and crystal accumulation models. Bulk rock chemistry and petrography are used to classify the samples …
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The igneous petrology, thermal history, and genesis of sedimentary rock-hosted Au deposits in the northern Battle Mountain mining district, Nevada
The Battle Mountain mining district in north-central Nevada hosts deposits of magmatic-hydrothermal origin, including porphyry, skarn, and distal disseminated deposits, as well as sedimentary-rock hosted Au deposits of uncertain origin. This dissertation examines the ages of magmatism and …
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Quantifying melting and chemical differentiation processes on Earth and the Moon
… four chapters that together investigate the igneous history of the Earth and the Moon. Each chapter explores new quantitative methods for combining experiments in igneous petrology with observed local and global major and trace element compositional variations and geophysical constraints. …
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Insights into magmatic processes from the crystal orientation mapping of igneous microstructures
… is now emerging as a useful tool for studying igneous rocks. In this thesis, I combine EBSD with field, petrographic and geochemical observations to tackle long-standing problems in igneous petrology. The first half of the thesis utilises EBSD to explore crystal interactions in magma, focusing …
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Data-driven approaches towards understanding trace metal and magmatic processes in arc volcanoes, with applications to Java, Indonesia
… understanding of subduction zone magmatism and igneous geochemistry. Here, I present a data-driven approach to both global and regional scale magmatic processes in subduction zones using a combination of global datasets, novel computational methods, and microanalytical petrology. Beginning with …
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Applications of Machine Learning to the Petrographic Analysis of Icelandic Gabbroic Xenoliths through Light, Electron and X-ray Microscopy
The following thesis can be divided into two main parts: the first consists of two chaptersdetailing the development of novel methods incorporating machine learning and deeplearning methods for use in petrographic analysis. The first of these chapters introduces adeep learning framework for the …
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Insights into the location, nature and influence of mantle heterogeneity in the Galápagos mantle plume
Ocean Island Basalts (OIBs) and Mid-Ocean Ridge Basalts (MORBs) provide a window into the composition, lithological properties, and volatile content of the Earth's, highly heterogeneous, convecting mantle. Our view of the Earth's mantle is, however, partially obscured by processes that influence …
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Crystal mobilisation in convecting magma chambers: an analogue experimental approach
Solidified igneous intrusions from originally liquid magma chambers display a large number of different sedimentary features. These features include the gravitational collapse of sidewalls producing slumps and the layering produced by gravitational settling of crystals. In the chamber fluid-dynamic …
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Magma genesis beneath active continental rifts
<p>The East African Rift System (EARS) and the West Antarctic Rift System (WARS) are two of the largest continental rift systems on Earth, but the processes governing rift dynamics remain controversial. The large volume and distinct chemistry of Cenozoic rift-related lavas, combined with …
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The Role of Cumulate Plagioclase Entrainment in the Steens Basalt, SE Oregon: Insights from the Magma Chamber Simulator
<p>The Steens Basalt, located in SE Oregon, is the oldest and most mafic member of the Columbia River Basalt Group (CRBG). Because the Steens Basalt contains large (up to 6 cm) and abundant (up to 40%) plagioclase crystals, it is classified as a Giant Plagioclase basalt (GPB). Understanding the …
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Timing and Source of Alkali Enrichment at Mt. Etna, Sicily: Constraints from Clinopyroxene Geobarometry and In Situ SR Isotope Data
Since 1971, Mt. Etna, Europe’s largest and most active volcano, has exhibited increased eruption frequency and explosivity. Associated with this increased activity, researchers have documented higher abundances of alkali elements (K, Rb, Cs) as well as elevated <sup>87</sup>Sr/<sup>86</sup>Sr in …
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Examining the past to prepare for the future: Quaternary magma storage in the Main Ethiopian Rift and implications for volcanic hazard and resource potential
Understanding how magma is stored within the crust, and what processes it might undergo, is of paramount concern to Earth scientists. Whilst advances in analytical techniques have revealed increasingly complex pictures of magma storage at arc and mid-ocean ridge settings, we still know relatively …
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Mineralogy and Geochemistry of Anorogenic Granitic Miarolitic Pegmatites Associated with the White Mountain Intrusive Suite, New Hampshire
… pegmatites associated with the White Mountain Igneous Province (WMIP), New Hampshire, were sampled and analyzed using modern analytical techniques including X-ray fluorescence, electron microprobe, scanning electron microscopy, and direct-coupled plasma spectrophotometry. Analytical results …
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PETROLOGIC AND GEOCHEMICAL ANALYSIS OF INTERMEDIATE TO MAFIC MAGNETITE-BEARING VOLCANIC FLOWS AND ASSOCIATED DIKES IN THE KNIGHT RANGE, GRANT COUNTY, NEW MEXICO
<p>The Knight Range of southwestern Grant County, New Mexico, is made up of a northeast-dipping package of Cretaceous-Tertiary volcanic, volcaniclastic, and sedimentary units. It is located in the Burro Uplift, south of the Tyrone mining district, at the intersection of the Mogollon-Datil volcanic …
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Understanding the evolution of compositional zoning in San Juan Volcanic Field ignimbrites using iron isotope ratios
… previous work, which has shown δ56Fe values of igneous rocks hover around the mean mafic earth value of 0.09‰ and increase in the most evolved high silica compositions. δ56Fe in the Carpenter Ridge ignimbrites shows a systematic increase in δ56Fe over much of the compositional range (68% to 78% …
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Microstructural evolution of silicate immiscible liquids in solidifying ferrobasalts
Evidence of silicate liquid immiscibility in ferrobasalts is provided by co-existing Fe- and Si-rich melt inclusions and Fe-rich droplets dispersed in the Si-rich glassy mesostasis of rapidly cooled rocks. Crucially, the different physical properties of these unmixed liquids mean that they may …