Theses and Dissertations at Montana State University (MSU)
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Item The rise of caldera forming eruptions: refining tools for understanding magma ascent(Montana State University - Bozeman, College of Letters & Science, 2022) Harris, Megan Ann; Chairperson, Graduate Committee: Madison Myers; This is a manuscript style paper that includes co-authored chapters.The rate at which magma moves from the magma chamber to the surface influences the amount of degassing and crystallization that occurs, which in turn controls the style and intensity of the ensuing eruption. Thus, our understanding of magma ascent rates is crucial to understanding and mitigating future volcanic hazards. The bulk of this dissertation revolves around using the diffusion of water through melt-filled pockets (embayments) in quartz crystals as an ascent speedometer, coupled with geochemical and textural analysis of co-erupted material. In Chapter Two, I apply and refine the water diffusion speedometer to establish timescales of ascent for the two eruptions that formed the modern-day Valles Caldera, with the aim of understanding whether these rates change during subsequent eruptions from the same caldera. In Chapter Three, I apply the diffusion speedometer to the opening behavior of the 1991 eruption of Mount. Pinatubo and compare the results to ascent rates obtained using independent petrologic methods (bubble number density and microlite number density). This chapter seeks to reconcile the several orders of magnitude offset in ascent rates produced by various geospeedometers. Finally, in Chapter Four, I explore the mechanisms by which embayments are formed in magmatic systems. I do this by conducting a survey of cathodoluminescence images of crystals taken from five volcanic systems to determine how the embayments interact with the internal zoning of the crystal. I then attempt to form embayments experimentally using a cold-seal pressure vessel under variable magmatic conditions. The culmination of this work emphasizes that embayments are robust and faithful recorders of a magma's journey from its source to the surface and may be a critical piece of evidence for unraveling the magmatic history leading to eruption. This dissertation includes both previously published and unpublished co-authored work.Item Novel models and observations of energetic events in the solar transition region(Montana State University - Bozeman, College of Letters & Science, 2021) Parker, Jacob Douglas; Chairperson, Graduate Committee: Charles C. Kankelborg; Dana Longcope was a co-author of the article, 'Modeling a propagating sawtooth flare ribbon as a tearing mode in the presence of velocity shear' in the journal 'Astrophysical journal' which is contained within this dissertation.; Charles Kankelborg was a co-author of the article, 'Determining the spectral content of MOSES images' submitted to the journal 'Astrophysical journal' which is contained within this dissertation.; Roy Smart, Charles Kankelborg, Amy Winebarger and Nelson Goldsworth were co-authors of the article, 'First flight of the EUV snapshot imaging spectrograph (ESIS)' submitted to the journal 'Astrophysical journal' which is contained within this dissertation.The solar atmosphere is an energetic and violent place capable of producing eruptions that affect us on earth. In order to better understand these events, so that we might improve out ability to model and predict them, we observe the sun from space to diagnose the local plasma conditions and track its evolution. The transition region, a thin region of the solar atmosphere separating the chromosphere from the corona, is where the solar atmosphere transitions rapidly from ten thousand, to one million kelvin and is therefore thought to play an important roll in the transfer of mass and energy to the hot corona. The sun's magnetic field, and magnetic reconnection, are thought to contribute to the increased temperature of the corona, since the cooler lower solar atmosphere cannot heat it via thermal conduction or convection. Explosive events, small solar eruptions likely driven by magnetic reconnection, are frequent in the transition region, making it an attractive area of the atmosphere to study and gather information on the processes. Using Computed Tomography Imaging Spectrographs (CTIS), capable of measuring spectral line profiles over a wide fields of view at every exposure, we find many eruptive events in the transition region to be spatially complex, three dimensional, and to evolve on rapid timescales. This demonstrates the utility of, and need to continue developing, CTIS style instruments for solar study since they provide a more complete picture of solar events, allowing us to improve our understanding of our closest star.Item Morphological adaptations facilitating attachment for archaeal viruses(Montana State University - Bozeman, College of Letters & Science, 2019) Hartman, Ross Alan; Chairperson, Graduate Committee: Mark J. YoungLittle is known regarding the attachment and entry process for any archaeal virus. The virus capsid serves multiple biological functions including: to protect the viral genome during transit between host cells, and to facilitate attachment and entry of the viral genome to a new host cell. Virus attachment is conducted without expenditure of stored chemical energy i.e. ATP hydrolysis. Instead, virus particles depend on diffusion for transportation and attachment from one host cell to another. This thesis examines the attachment process for two archaeal viruses. Sulfolobus turreted icosahedral virus (STIV) is well characterized for an archaeal virus. Still, no information is available concerning STIV attachment or entry. The research presented here shows that STIV attaches to a host cell pilus. Furthermore, combining the previously determined atomic model for the virus, with cryo-electron tomography, a pseudo-atomic model of the interaction between the host pilus and virus was determined. Based on this data, a model is proposed for the maturation of the virus capsid from a noninfectious to an infectious form, by dissociation of accessory proteins. Finally, a locus of genes is identified in the host cell, encoding proteins essential for viral infection, that are likely components of the pili structure recognized by STIV. The isolation of a new archaeal virus, Thermoproteus Piliferous Virus 1 (TSPV1), is also presented here. The TSPV1 virion has numerous fibrous extensions from the capsid, of varying length, that are the first observed for any virus. The capsid 2-3nm fibers likely serve to extend the effective surface area of the virus, facilitating attachment to host cells. Characterization of this new virus was conducted, including genome sequencing and determination of the protein identity for the capsid fibers. The research presented here provides a substantial advancement in our knowledge of the attachment process for archaeal viruses. Attachment to host pili is now emerging as a common theme for archaeal viruses. Furthermore, the isolation of the new archaeal virus TSPV1 demonstrates a novel strategy to increase the probability of interaction between a virus and host cell.Item Statistical validation of a numerical snow cover model and preliminary experimental results to facilitate model improvement(Montana State University - Bozeman, College of Engineering, 2000) Lundy, Christopher Charles