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dc.contributor.advisorLassiter, John C.en
dc.contributor.advisorGardner, James Edward, 1963-en
dc.creatorSzramek, Lindsay Annen
dc.date.accessioned2011-03-04T22:06:36Zen
dc.date.accessioned2011-03-04T22:08:09Zen
dc.date.available2011-03-04T22:06:36Zen
dc.date.available2011-03-04T22:08:09Zen
dc.date.created2010-08en
dc.date.issued2011-03-04en
dc.date.submittedAugust 2010en
dc.identifier.urihttp://hdl.handle.net/2152/ETD-UT-2010-08-1764en
dc.descriptiontexten
dc.description.abstractMafic magma is the most common magma erupted at the surface of the earth. It is generated from partial melting of the mantle, which has been subdivided into end-members based on unique geochemical signatures. One reason these end members, or heterogeneities, exist is subduction of lithospheric plates back into the mantle. The amount of elements, such as Cl and K, removed during subduction and recycled into the deep mantle, is poorly constrained. Additionally, the amount of volatiles, such as Cl, that are recycled into the deep mantle will strongly affect the behavior of the system. I have looked at Cl and K in HIMU source melts to see how it varies. Cl/Nb and K/Nb suggest that elevated Cl/K ratios are the result of depletion of K rather than increased Cl recycled into the deep mantle. After the mantle has partially melted and mafic melt has migrated to the surface, it usually erupts effusively or with low explosivity because of its low viscosity, but it is possible for larger eruptions to occur. These larger, Plinian eruptions, are not well understood in mafic systems. It is generally thought that basalt has a viscosity that is too low to allow for such an eruption to occur. Plinian eruptions require fragmentation to occur, which means the melt must undergo brittle failure. This may occur if the melt ascends rapidly enough to allow pressure to build in bubbles without the bubbles expanding. To test this, I have done decompression experiments to try to bracket the ascent rate for two Plinian eruptions. One eruption has a fast ascent, faster than those seen in more silicic melts, whereas the other eruption is unable to be reproduced in the lab, however it began with a increased viscosity in the partly crystallized magma. After fragmentation and eruption, it is generally thought that tephra do not continue to crystallize. We have found that crystallinity increases from rim to core in two basaltic pumice. Textural data along with a cooling model has allowed us to estimate growth rates in a natural system, which are similar to experimental data.en
dc.format.mimetypeapplication/pdfen
dc.language.isoengen
dc.subjectBasaltic volcanismen
dc.subjectMafic magmaen
dc.subjectHIMUen
dc.subjectPlinian eruptionsen
dc.subjectCooling modelen
dc.subjectFragmentationen
dc.subjectAscenten
dc.subjectMantle recyclingen
dc.subjectCrystallizationen
dc.subjectBasaltic pumiceen
dc.titleBasaltic volcanism : deep mantle recycling, Plinian eruptions, and cooling-induced crystallizationen
dc.date.updated2011-03-04T22:08:09Zen
dc.contributor.committeeMemberCarlson, Williamen
dc.contributor.committeeMemberHoughton, Bruceen
dc.contributor.committeeMemberRowe, Michael C.en
dc.description.departmentGeological Sciencesen
dc.type.genrethesisen
thesis.degree.departmentGeological Sciencesen
thesis.degree.disciplineGeological Sciencesen
thesis.degree.grantorUniversity of Texas at Austinen
thesis.degree.levelDoctoralen
thesis.degree.nameDoctor of Philosophyen


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