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Showing 1 to 20 of 205 for “"Magmas"”.
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Magpy: A Python Package for Magmas
<p>There exist a multitude of computational tools available to mathematicians, such as interactive and automated theorem provers, finite counter-example generators, and computer algebra systems, most of which have a complicated installation process, unintuitive syntax, a lack of comprehensiveness …
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Field, geochemical, and experimental studies of aluminous arc magmas
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1991.
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The heterogeneity and volatile content of Earth’s mantle, magmas and crust
… of the mantle, subducted oceanic crust, and arc magmas as well as the structure of slow spreading ocean crust and the heterogeneity of Earth’s upper mantle. In Chapter 2, I directly explore the halogen (F and Cl) content of mantle minerals in situ, then use these measurements to assess the …
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Geochemical Constraints of Porphyry Cu Deposits-Forming Magmas in Sonora, Mexico
… 2008). These factors influence the capacity of magmas to concentrate and transport metals such as Cu. This thesis investigates the geochemical signatures associated with fertile and barren magmatic systems in Sonora, Mexico. Using zircon trace-element geochemistry, U–Pb geochronology, and …
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Water and fluorine contents in Mt. Hood magmas recorded by plagioclase phenocrysts
… is the most well-studied volatile component of magmas, but other volatiles species (e.g. F) are the subject of increasing interest (Dasgupta and Dixon 2009). Magmatic volatiles are often measured in melt inclusions (MIs) (e.g. Straub and Layne 2003; Plank et al. 2013), but may be uncommon in …
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Evidence From High Ni Olivine For Diverse Primitive Magmas In Cascade Volcanism
<p>Minor element abundances in olivine phenocrysts from primitive, high-Mg# lavas (Mg/Mg+Fe >0.60) are used to explore the nature of magma genesis in the Cascade subduction system. Electron-microprobe analyses were obtained for olivine phenocrysts in primitive basalt from central Oregon and …
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The petrology and geochemistry of Precaldera Magmas, Long Valley Caldera, Eastern California
… of the caldera suggest that: (I) the basaltic magmas were generated from a lherzolite partial melt modified by minor crystal fractionation (limited fractionation due to their high incompatible element content) and contamination by older sialic rocks or their derivatives (represented by granitic …
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Differentiation in impact melt sheets as a mechanism to produce evolved magmas on Mars
… been attributed to fractional crystallization of magmas resulting from low-degree mantle melting analogous to ocean island or rift settings on Earth. In this study, we investigate the hypothesis that differentiation of impact-generated melts provides a viable alternative explanation for the …
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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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Petrologic Significance of Multiple Magmas in the Quottoon Igneous Complex, NW British Columbia and SE Alaska
The quartz dioritic Quottoon Igneous Complex (QIC) is a major Paleogene (65-56 Ma) magmatic body in NW British Columbia and SE Alaska that was emplaced along the Coast shear zone (CSZ). The QIC contains two different igneous suites that provide information about source regions, magmatic processes …
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Petrogenesis of hybrid porphyry pipes and evolution of alkaline magmas in the Kanabeam Igneous Complex, Southern Namibia
The linear Kuboos Bremen Igneous Province (KBIP) stretches 270km from the South African Atlantic coast north-eastwards into southern Namibia, and was emplaced at approximately 500Ma. One central complex within the KBIP is the Kanabeam Igneous Complex (KIC) where practically all the rock types found …
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Why are there no low-δ18O magmas In convergent margins? A case of the Central Andes, Northern Chile
It has long been thought that low-δ 18O magmas (<5.7‰) are only found in extensional tectonic settings. Low-δ 18O magmas are rare, worldwide, especially in subduction zone settings. The main objective of this study was to conduct a search for low-δ 18O magmas in the Central Volcanic Zone (CVZ) of …
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Petrogenesis and evolution of alkalic basaltic magmas in a continental intraplate setting: the South Auckland Volcanic Field, New Zealand
… source is required to produce primary group B magmas, whereas primary group A magmas are generated from < 11 % melting of a spinel-peridotite source. Differentiation of basalts from each group is dominated by olivine and clinopyroxene fractionation, and only minor plagioclase in group A. Both …
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The Middle Fork Plutonic Complex: a plutonic association of coeval peralkaline and metaluminous magmas in the north-central Alaska Range
… groupings suggest that at least three different magmas formed the MFPC; scatter of isotopic data reflects mu- tual contamination and assimilation. Trends in whole rock and mineral chemistry also reflect interactions between the magmas. Consanguinous hypersolvus syenite and AF granite mineralogy …
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A multi-isotopic geochemical investigation of the Lower Zone, Bushveld Complex, South Africa: implications for a crustal component for parental magmas
… These high 18O values suggests the Bushveld magmas sourced a crustal reservoir, either through crust assimilation or recycled crustal materials in the mantle source. This is the first study utilizing the Re-Os isotope system for the Lower Zone. The Osi values for the NG2 suite range from …
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Oxygen and radiogenic isotope constraints on the generation of coexisting silica-undersaturated and oversaturated felsic magmas of the Ditrau Alkaline Massif (Romania)
… (1) both silicaundersaturated and oversaturated magmas evolve from the same mantle-derived, undersaturated melt, with the oversaturated rocks being produced by crustal assimilation (Foland et al., 1993); (2) both are derived from the same mantle source, but do not evolve from the same parental …
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Origin and evolution of parental magmas associated with Pliocene-Quaternary low-silica volcanism within the Altiplano-Puna Volcanic Complex of northern Chile
… Physical interactions between mafic and felsic magmas for this arc are therefore difficult to recognize due to the differentiation of mantle-derived magma during ascent through the thickened crust and a corresponding lack of erupted primitive lavas. However, a rare concentration of less evolved …
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Crystallisation history of rhyolite magmas at Tarawera volcano, New Zealand, from in-situ 238U-230Th disequilibrium dating and trace element geochemistry of zircon
… crystallisation histories in all of the erupted magmas. Rim analyses on unpolished crystal faces were performed to minimise the overlap of the ion beam onto different age zones. This documents the last stage of crystal growth. Zircon crystallisation frequently stopped long before eruption (1->100 …
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Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-temperature Magmatic Conditions And Non-laurentian Origin Of Earth’s Most Zircon Fertile Magmas
… processes responsible for creating Zr-enriched magmas (Chapter 3).</p>
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