Lava flows of Tertiary-Quaternary age occur in Enoch Valley, Upper Valley, and Slug Valley in southeastern Idaho. The basalts in Upper Valley and Enoch Valley contain olivine (Fo69 to Fo37), plagioclase (An62 to An39), augite and Fe-Ti oxides. The lava in Slug Valley lacks plagioclase, but contains sanidine (Or70 to Or56) with a trace of biotite and amphibole, and thus, has been termed alkali trachyte. Black Mountain, on the eastern side of Bear Lake, northeastern Utah, is capped by basalt. Minerals present include olivine (Fo83 to Fo72), plagioclase (An71 to An53 J, augite, and magnetite. Chemically, the basalt of Enoch Valley is comparable to olivine tholeiite of the Snake River Plain, as it contains olivine and hypersthene in the norm. The basalt of Upper Valley contains a greater amount of Si02 and K2O and less MgO than tholeiite of the Snake River Plain. This basalt contains normative quartz and hypersthene and is classified as tholeiite. The presence of nepheline and olivine in the norm of the basalt from Black Mountain indicates that it is an alkali-olivine basalt. The lava from Slug Valley contains high K and Mg, moderate Si, and low Al and Na. It is similar to lamproites of orenditic affinity. The temperatures of crystallization calculated from co-existing olivine and pyroxene, range from 1,015 degrees C to 996 degrees C for the valley basalts, and range from 1,021 degrees C to 1,002 degrees C for the alkali trachyte. The temperature calculated for the basalt sample from Black Mountain is 1,015 degrees C. The temperatures estimated using coexisting magnetite and ilmenite range from 1,021 degrees C to 978 degrees C for the valley basalts. The proposed origin of the Enoch Valley basalt is that it is a direct product of partial melting of a mantle of pyrolite composition. Fractionation, during ascent of the magma, could possibly have produced the Upper Valley lava. The basalt on Black Mountain was possibly derived as the result of partial melting of a pyrolitic mantle as well, but due to differences in mineralogy and normative constituents, it seems to be unrelated to the valley basalts. The origin of the Slug Valley alkali trachyte is uncertain. This lava may have been generated from a mica peridotite mantle and is possibly related to the Leucite Hills lava in Wyoming.

Geóloga / El Cerro La Torta es un domo volcánico riolítico, de 34 ka de edad, ubicado en la zona de El Tatio, al oeste de los Cerros de Tocorpuri, en la frontera con Bolivia, a 1270 km al noreste de Santiago y 100 km al este de Calama. Abarca un área de 12 km2 y un volumen de 4,7 km3 a una altura de 5090 m s.n.m. El objetivo principal de este estudio es reconstruir los procesos ígneos que ocurrieron en evolución del magma que formó el Cerro La Torta mediante inclusiones vítreas. Para esto se realizaron análisis en microsonda electrónica y ablación láser luego de un detallado trabajo de petrografía de inclusiones vítreas hospedadas en anfíbol y plagioclasa. El domo Cerro la Torta erupcionó a partir de un magma riolítico, rico en potasio y con un 74,5% wt de sílice desde una fuente magmática que cristalizó a presiones de entre 114 y 185 MPa, equivalentes a profundidades entre los 90 y 2390 m. bajo el nivel del mar. La temperatura de cristalización de las distintas fases y sus respectivas inclusiones varía entre 949 y 723 °C en promedio. La fugacidad de oxígeno del fundido (logfO2) es -12,3, indicando un ambiente oxidante, y el porcentaje de agua del fundido, 4,9% wt. A pesar de los datos anteriores, las inclusiones estudiadas registran un último evento de cristalización de fases minerales debido a que un magma de 74% de sílice no puede fraccionar piroxeno, por lo que la fuente real está más profunda y menos diferencia. La gran presencia de andesina indica que este magma parental real, es andesítico. Se establecen dos modelos de fuente magmática para La Torta. i) Fuente magmática más profunda que los 2,6 km de espesor, que en un principio (0,8 Ma) tenía composición andesítica a dacítica, erupcionando el volcán Tocorpuri y, posteriormente, los Cerros de Tocorpuri. ii) Fuente magmática netamente riolítica alimentada por otra más profunda y primitiva. Este magma contenía enstatita y magnesio-hornblenda que por un calentamiento provocado por otro cuerpo magmático más primitivo se disolvieron violentamente, enriqueciendo el sistema en Ni, Cr y tierras raras pesadas, quedando escasos micro-fenocristales de enstatita. Las nuevas fases de Mg.-Hbl asimilaron estos elementos tanto en su cristal como en sus inclusiones. Posteriormente, el magma fue ascendiendo y cristalizando fraccionadamente a fases minerales como cuarzo y biotita, registrando un decaimiento en la concentración de los elementos compatibles de las inclusiones de centro a borde. Luego de un periodo de residencia suficiente para formar fenocristales de hasta un cm de largo, ocurre una descompresión y recalentamiento debido a la fuente de calor aportada por el APMB, que creó las texturas de reabsorción en cuarzo y anfíbol. / 22/12/2019

The Roza flow of the Columbia River Basalt group in Washington State U.S.A. extruded at about 15 Ma during intermediate geomagnetic polarity. The Roza is underlain by normal polarity flows and overlain by reversed units. The Roza is an extensive flow, up to 60 in thick. As the remanence-blocking isotherms progressed into the flow, it recorded a short continuous segment of the transitional geomagnetic field. Our studies show limited thermal remagnetization in the underlying flow, and we infer that groundwater was effective in extracting the heat. The extent of basement heating was further reduced by the insulating scoria immediately beneath Roza. Hence, the Roza flow cooled symmetrically from its top and base. Samples from the drilicores acquired drilling induced remanent magnetization (DIRM), shown to be well modelled as an isothermal remanent magnetization produced in nonuniform fields of the order of 10 mT at the rim of the drillstring. Alternating field demagnetization was usually successful in removing the DIRM. The remanence stability is higher in the top third of Roza, due to smaller magnetic particles, than in the lower two thirds of the flow, where the magnetic properties are nearly uniform. The stability profile corresponds to the entablature/colonnade subdivision. High temperature subsolidus oxidation of the titanomagnetites increased with height in the flow, altering the primary symmetric intraflow distribution. The declination of the Roza flow sampled at numerous outcrops is consistently about 189°. In a 54 m drillcore section, Roza inclinations become more negative towards the flow interior, consistent with its magnetostratigraphic position. Superimposed is a symmetric, rapid change in inclination from -2 to -15° and back to -5°. The flow's thermal history predicts that these fluctuations have a characteristic time between 15 and 60 years, such that the inclination changed at a rate of 1/2 to 2° per year, showing that the directions of this transitional field fluctuated several times more rapidly than the present geomagnetic field. However, considering the generally reduced intensity during transitions, these fluctuations might not be unusual. / Graduation date: 1990

Obsidian Dome is a 550-650 year old, 1.5 by 1.8 km extrusion of high silica rhyolite situated along the Inyo Craters in eastern California. Field, and observations of drill core, reveals discrete metre-scale thick zones of rhyolitic glass exposed along the margin of Obsidian Dome as well as within its interior. Millimetre-scale flow-banded obsidian, pumice and rhyolite range from planar to chaotically folded, the latter a product of ductile, compressive deformation. Fractures, some of which display en-echelon splitting patterns are a result of brittle failure. Taken together, these features along with others, result from flow during lava dome growth and suggest complex emplacement patterns signified by vesiculation, crystallization and repeated brittle-ductile deformation, owing to episodic crossing of the glass transition. Evidence further shows that gas loss from the system occurred due to explosions, pumice formation and also brecciation of the melt as it episodically crossed the glass transition. Loss of gas by these mechanisms along with the inherent high viscosity of rhyolite melt explains the large amount of glass found on and within Obsidian Dome and other similar rhyolite extrusions in comparison to less silica-rich systems.

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Rapporten behandlar en produktutveckling av framtidens TV-fäste. Teknik och form hos TV-apparater utvecklas varje dag, detta leder till att TV-fästen måste anpassas för att följa trenderna. I samarbete med företaget People of Lava har en designprocess utförts för att utveckla framtidens TV-fäste. Rapporten behandlar en djup marknadsundersökning där statistiska, kvalitativa samt kvantitativa undersökningar utförs. Detta ligger sedan som grund för en target cost där ett produktionspris söks för att försäkra sig om en önskad vinstmarginal för företaget. Utifrån den bestämda kostnaden genomförs konceptgenereringar där form och funktioner utvecklas. De genererade koncepten utvärderas via konceptvalsmatriser och diskussion med såväl företaget som möjliga köpare av produkten. Resultatet av processen är ett TV-fäste som inte är anpassad till den standard som vanligtvis används hos TV-fästen. Ett exklusivt fäste med integrerad förvaring som står ut på marknaden och blir en del av inredningen. Fästet erbjuder företaget en miljövänlig tillverkning i Sverige, då närproducerat material valts för produkten.

The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file. Title from PDF of title page (University of Missouri--Columbia, viewed on December 30, 2009). Thesis advisor: Dr. Eric Sandvol. Includes bibliographical references.

Thesis (M.S.)--Oregon State University. / Includes bibliographical references (leaves 62-65). Also available on the World Wide Web.

The evolution of rhyolitic lava from effusion to cessation of activity is poorly understood. Recent lava dome eruptions at Unzen, Colima, Chaiten and Soufrière Hills have vastly increased our knowledge on the changes in behaviour of active domes. However, in ancient domes, little knowledge of the evolution of individual extrusion events exists. Instead, internal structures and facies variations can be used to assess the mechanisms of eruption. Rhyolitic magma rising in a conduit vesiculates and undergoes shear, such that lava erupting at the surface will be a mix of glass and sheared vesicles that form a permeable network, and with or without phenocryst or microlites. This foam will undergo compression from overburden in the shallow conduit and lava dome, forcing the vesicles to close and affecting the permeable network. High temperature, uniaxial compression experiments on crystal-rich and crystal-poor lavas have quantified the evolution of porosity and permeability in such environments. The deformation mechanisms involved in uniaxial deformation are viscous deformation and cracking. Crack production is controlled by strain rate and crystallinity, as strain is localised in crystals in crystal rich lavas. In crystal poor lavas, high strain rates result in long cracks that drastically increase permeability at low strain. Numerous and small cracks in crystal rich lavas allow the permeable network to remain open (although at a lower permeability than undeformed samples) while the porosity decreases. Flow bands result from shear movement within the conduit. Upon extrusion, these bands will become modified from movement of lava, and can therefore be used to reconstruct styles of eruption. Both Ngongotaha and Ruawahia domes, from Rotorua caldera and Okataina caldera complex (OCC) respectively, show complex flow banding that can be traced to elongated or aligned vents. The northernmost lobe at Ngongotaha exhibits a fan-like distribution of flow bands that are interpreted as resulting from an initial lava flow from a N – S trending fissure. This flow then transitioned into intrusion of obsidian sheets directly above the conduit, bound by wide breccia zones which show vertical movement of the sheets. Progressive intrusions then forced the sheets laterally, forming a sequence of sheets and breccia zones. At Ruawahia, the flow bands show two types of eruption; long flow lobes with ramp structures, and smaller spiny lobes which show vertical movement and possible spine extrusion. The difference is likely due to palaeotopography, as a large pyroclastic cone would have confined the small domes, while the flow lobes were unconfined and able to flow down slope. The vents at Ruawahia are aligned in a NE – SW orientation. Both domes are suggested to have formed from the intrusion of a dyke. The orientations of the alignment or elongation of vents at Ngongotaha and Ruawahia can be attributed to the overall regional structure of the Taupo Volcanic Zone (TVZ). At Ngongotaha, the N – S trending elongated vent is suggested to be controlled by a N – S trending caldera collapse structure at Rotorua caldera. The rest of the lobes at Ngongotaha, as well as other domes at Rotorua caldera, are controlled by the NE – SW trending extensional regional structure or a NW – SE trending basement structure. The collapse of Rotorua caldera, and geometry of the deformation margin, are related to the interplay of these structures. At Ruawahia, the NE – SW trending vent zone is parallel to the regional extension across the OCC, as shown by the orientation of intrusion of the 1886AD dyke through the Tarawera dome complex. The NE – SW trending regional structures observed at both Rotorua caldera and Okataina caldera complex are very similar to each other, but differ from extension within the Taupo rift to the south. Lava domes, such as Ngongotaha, that are controlled by this structure show that the ‘kink’ in the extension across Okataina caldera complex was active across Rotorua caldera during the collapse at 240 ka, and possibly earlier. This study shows the evolution of dyke-fed lava domes during eruption, and the control of regional structures in the location and timing of eruption. These findings improve our knowledge of the evolution of porosity and permeability in a compacting lava dome, as well as of the structures of Rotorua caldera, the longevity of volcanic activity at dormant calderas and the hazard potential of dyke-fed lava domes.

The Tertiary lavas of Northern Skye, N.W. Scotland comprise a pile of flat-lying, predominantly basaltic, volcanic flows. The lavas are the earliest products of the igneous activity on Skye, later manifestations including the gabbroic Cuillin complex and the Red Hills granites. The activity occurred from approximately 65 Ma to 50 Ma (Palaeocene to Eocene) within a continental environment. The lava pile can be divided compositionally into three magma-types, the Skye Main Lava Series (SMLS), lavas of which constitute the majority of the pile, and the less abundant Preshal Mhor (PM) and Fairy Bridge (FB). This study concerns the petrogenesis of the three magma-types. The three magma-types have a normal basaltic mineralogy; phenocrysts include olivine, plagioclase and sparse clinopyroxene; groundmasses comprise varying proportions of olivine, plagioclase, clinopyroxene, and titanomagnetite. A typical flow comprises four zones: a basal amygdaloidal layer, a massive central portion possibly showing columnar jointing, a purple rotted amygdaloidal layer, and a capping red or brown bole. The fractional crystallisation of the SMLS w#s a two-stage process initially involving the precipitation of olivine (± minor Cr-spinel), and later fractionation of olivine and plagioclase ± clinopyroxene. The majority of the lavas assimilated some lower crustal Lewisian granulite en route to the surface. The most basic lavas are the most contaminated. Major and trace element modelling suggests that the SMLS magmas were generated by 15 % melting, at an above-average mantle potential temperature, within the spinel-garnet transition zone at a depth of - 100 km. The magmas subsequently last equilibrated with mantle host rocks at 15 kb (- 45 km).