Gas Migration Through Crystal-Rich Mafic Volcanic Systems and Application to Stromboli Volcano, Aeolian Islands, Italy

Show simple item record Belien, Isolde L.M.B. (Leo Maria Beatrijs), 1985- 2012-03-29T16:41:07Z 2012-04-28T17:07:09Z 2011-09
dc.description xvii, 171 p. : ill. (some col.) en_US
dc.description.abstract Crystals influence the migration of gas through magma. At low concentrations, they increase the bulk fluid properties, especially viscosity. At concentrations close to maximum packing, crystals form a rigid framework and magma cannot erupt. However, erupted pyroclasts with crystal contents close to the packing concentration are common at mafic volcanoes that exhibit Strombolian behavior. In this dissertation, I study the influence of solid particles on gas migration. I apply my results to Stromboli volcano, Italy, type locality of the normal Strombolian eruptive style, where gas moves through an essentially stagnant magma with crystallinity ∼50%. Specifically, I investigate the effect of crystals on flow regime, gas content (Chapter II), bubble concentration (number densities), bubble shapes, bubble sizes (Chapter III), and bubble rise velocities (gas flux) (Chapter IV). I find that gas-liquid flow regimes are not applicable at high particle concentrations and should be replaced by new, three-phase (gas-liquid-solid) regimes and that degassing efficiency increases with particle concentration (Chapter II). In Chapter III, I show that crystals modify bubble populations by trapping small bubbles and causing large bubbles to split into smaller ones and by modifying bubble shapes. In Chapter IV, I model Stromboli's crystal-rich magma as a network of capillary tubes and show that bubble rise velocities are significantly slower than free rise velocities in the absence of particles. In each chapter, I use analogue experiments to study the effect of different liquid and solid properties on gas migration in viscous liquids. I then apply my analogue results to magmatic conditions using simple parameterizations and/or numerical modeling or by comparing the results directly to observations made on crystal-rich volcanic rocks. Chapter V proposes a mechanism for Strombolian eruptions and gas migration through the crystalrich magma in which the effect of crystals is included. This model replaces the current twophase "slug" model, which cannot account for the high crystallinity observed at Stromboli. There are three appendices in this dissertation: a preliminary study of the influence of particles on gas expansion, image analysis methods, and the numerical code developed in Chapter IV. This dissertation includes previously published and unpublished co-authored material. en_US
dc.description.sponsorship Committee in charge: Katharine Cashman, Chairperson; Alan Rempel, Member; Mark Reed, Member; Raghuveer Parthasarathy, Outside Member en_US
dc.language.iso en_US en_US
dc.publisher University of Oregon en_US
dc.relation.ispartofseries University of Oregon theses, Dept. of Geological Sciences, Ph. D., 2011;
dc.rights rights_reserved en_US
dc.subject Geology en_US
dc.subject Earth sciences en_US
dc.subject Gas migration en_US
dc.subject Crystal-rich mafic volcanoes en_US
dc.subject Stromboli (Italy) en_US
dc.subject Aeolian Islands en_US
dc.title Gas Migration Through Crystal-Rich Mafic Volcanic Systems and Application to Stromboli Volcano, Aeolian Islands, Italy en_US
dc.type Thesis en_US

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