• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 55
  • 25
  • 15
  • 8
  • 8
  • 7
  • 2
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 155
  • 38
  • 25
  • 19
  • 19
  • 16
  • 16
  • 13
  • 12
  • 12
  • 10
  • 10
  • 9
  • 9
  • 8
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Selected trace elements in Hawaiian lavas by atomic absorption spectrophotometry

Herlicska, Edward January 1967 (has links)
Typescript. / Thesis (Ph. D.)--University of Hawaii, 1967. / Bibliography: leaves 243-254. / xv, 254 l illus., tables
32

Geochemical investigations of ordinary chondrites, shergottites, and Hawaiian basalts /

Reynolds, Valerie Slater, January 2005 (has links) (PDF)
Thesis (Ph. D.) -- University of Tennessee, Knoxville, 2005. / Vita. Includes bibliographical references (p. 57-76). Also available via World Wide Web.
33

Petrology of inclusion-rich lavas at Minna Bluff, McMurdo Sound, Antarctica implications for magma origin, differentiation, and eruption dynamics /

Scanlan, Mary K. January 2008 (has links)
Thesis (M.S.)--Bowling Green State University, 2008. / Document formatted into pages; contains xi, 221 p. : ill. (some col.), maps. Includes bibliographical references.
34

Geothermometry, crystallization, and the pahoehoe/àà transition in Mauna Loa lavas /

Montierth, Charlene, January 1999 (has links)
Thesis (Ph. D.)--University of Oregon, 1999. / Typescript. Includes vita and abstract. Includes bibliographical references (leaves 129-135). Also available for download via the World Wide Web; free to University of Oregon users. Address: http://wwwlib.umi.com/cr/uoregon/fullcit?p9948026.
35

Petrochemistry of mafic rocks from the Harbour Main group (Western Block), Conception Bay, Avalon Peninsula, Newfoundland /

Cameron, Kevin J. January 1986 (has links)
Thesis (M.Sc.) -- Memorial University of Newfoundland. / Typescript. Bibliography : leaves 175-189. Also available online.
36

Petrographie und Geochemie spätkretazisch-alttertiärer Laven und Subvulkanite der nördlichen Lut, Ost-Iran

Rezvani Khorasani, Reza. January 1982 (has links)
Thesis (doctoral)--Universität Hamburg, 1982. / Includes bibliographical references (p. 218-229).
37

Caracterización de la cristalización posteruptiva de la colada de lava de 1971 del Volcán Villarrica mediante el análisis de distribución de tamaño de cristales

Varela Moreira, Exequiel Ignacio January 2017 (has links)
Geólogo / La erupción de 1971 del volcán Villarrica tuvo una duración de dos días en los cuales se produjeron dos coladas de lava que fluyeron por el Valle pedregoso y por el valle del Chaillupén, con extensiones de 6 y 14 km, respectivamente. La actividad previa estuvo marcada por desgasificación aproximada de dos meses. El flujo de lava más extenso (valle del Chaillupén) constituyó una colada de tipo Aa. Esta colada fue muestreada con la intención de establecer una relación entre la cristalización sin-posteruptiva y la desgasificación. Para este estudio se extrajeron muestras de distintos horizontes verticales y de dos lugares distintos del flujo. Uno proximal en un levee y otro distal en un frente de lava. De estas muestras se obtuvieron imágenes de piroxenos, plagioclasas y óxidos de hierro-titanio mediante un microscopio electrónico de barrido FEIQuanta 200MK2 SEM. Para la caracterización de las vesículas se utilizaron imágenes fotográficas de las muestras. Las imágenes fueron modificadas mediante el software INCA y analizadas utilizando el software JMicroVision y CSD corrections. Se encontraron CSD convexos en las fases de plagioclasa y piroxenos, no así en la de óxidos de hierro. Los BSDs presentan convexidades más pronunciadas, con poblaciones de vesículas considerablemente menoress que los CSDs. Para analizar estos CSDs se utilizaron diagramas bilogarítmicos y de función de distribución acumulada. Los diagramas de distribución de cristales utilizados permiten señalar que la distribución de plagioclasas en ambos set es fractal mientras que la de piroxeno es lognormal. En el caso de plagioclasa, las dimensiones fractales encontradas se condicen con una fuerte correlación entre las variables involucradas (log tamaño-log población) y una baja complejidad. La tasa de crecimiento utilizada entrega tiempos que se adecúan al escenario geológico ocurrido en la erupción del volcán Villarrica. Por otro lado, los BSDs permiten comprender el principal mecanismo de crecimiento de burbujas en la colada de lava, siendo este la coalescencia. Si bien las poblaciones de plagioclasa y vesículas siguen distribuciones fractales dadas por una ley potencia, no es posible establecer ninguna relación temporal significativa entre ambas, para sortear este problema se proponen dos alternativas, aumentar el tamaño de las vesículas estudiadas y disminuir el tamaño de cristales a un valor significativo, cinéticamente hablando. / Este trabajo ha sido financiado por el Centro de excelencia en geotermia de los Andes, CEGA
38

Petrology of quaternary alkaline lavas from the Alligator Lake volcanic complex, Yukon Territory, Canada

Eiché, Greg. January 1985 (has links)
No description available.
39

Resident stakeholder perceptions of lava flow hazard diversion strategies and protective measures for infrastructure and commercial and private property on Kīlauea and Mauna Loa volcanoes, Hawai‘i

Reeves, Ashleigh, Gregg, Christopher, Lindell, Michael K, Joyner, Timothy A, Houghton, Bruce 04 April 2018 (has links)
Decisions to interfere with the natural path of lava are constrained by geological, engineering and logistical factors; and legal, environmental and socio-cultural considerations. Lava flows erupted from several volcanoes around the world have threatened people and their property, motivating them to take actions to prevent or slow its advance by diverting the flow direction using channels, berms and explosives or obstructing the lava by quenching with water or armoring. Property to be protected has included government, public, commercial and private property ranging from cities and harbors to personal property. The earliest known attempt to influence the path of lava occurred in 1669 on Mount Etna, Italy, but more recent experience there occurred in the 1980s-90s. Several eruptions at Kīlauea and Mauna Loa volcanoes in Hawai‘i also provided abundant experience (1881, 1935, 1942, 1955, 1960 and several times during the on-going 1983- present eruption of Kīlauea). Additional experience relates to experimental tests and an untested berm on Mauna Loa. Most recently though, local businessmen on Kīlauea constructed earthen berms to protect their property and the local utility authority constructed novel protective structures around electric utility poles. Decisions to use mitigation strategies may be based on expert scientific opinion, but public opposition has been reported to alone be able to prevent lava mitigation. In 2014, public opinions about the use of traditional mitigation strategies (diversion by berms or bombing) to protect commercial and residential areas of Puna were mixed among residents, but there appeared to be no opposition to a new mitigation strategy that protected key areas of the electrical infrastructure and supply of electricity. To help understand public opinion about this and various mitigation strategies and people’s acceptance of additional risk to personal property to help protect important elements of their community, we conductied questionnaire surveys among residents on Kīlauea and Mauna Loa as part of a multi-university NSF Hazards SEES project. We evaluated crisis experience, hazard zonation, and community bondedness, in addition to socio-demographic and cultural factors, with beliefs concerning mitigation, including effectiveness of mitigation strategies for lava flows and others hazards; financial and legal considerations; and requirements for specialized knowledge, skills and cooperation.
40

Evolução do vulcanismo histórico de 1580 A.D. da Ilha de São Jorge, Arquipélago dos Açores

Rossetti, Marcos de Magalhães May January 2017 (has links)
A erupção histórica de 1580 A.D. ocorreu ao sudoeste da Ilha de São Jorge, Açores recobrindo uma área total de 4 km². Este trabalho teve como objetivo caracterizar as diferentes morfologias de lava de 1580 A.D, juntamente com a definição de padrões petrográficos e geoquímicos. A erupção gerou quatro flow fields: Ribeira do Almeida, Queimada, Ribeira do Nabo I e Ribeira do Nabo II. A descrição detalhada das lavas permitiu identificar spiny, sheet, e slabby pahoehoe e derrames do tipo ‘a´ā. Próximo aos cones, derrames do tipo ‘a´ā são descritos. Com a constante erupção, estas lavas fluem em direção a costa formando deltas de lava ao entrar em contato com a água. Estes deltas geram um relevo sub-horizontal favorecendo a colocação de derrames do tipo sheet pahoehoe. A contínua alimentação interna favorece o espessamento dos derrames, podendo gerar o rompimento da superfície formando derrames slabby pahoehoe. Os estágios finais da erupção são marcados por derrames do tipo ‘a´ā canalizados lateralmente e sobre os derrames do tipo sheet pahoehoe. A variação na superfície dos derrames é controlada pelas taxas de efusão e pela topografia. Petrograficamente, todas as lavas da erupção de 1580 A.D. são olivina basaltos. Os dados geoquímicos indicam uma afinidade magmática alcalina com os termos menos diferenciados localizados na região de Ponta Queimada. Isto pode ser explicado por uma constante recarga de magma mais primitivo na câmara magmática. Os padrões de ETR normalizados sugerem que os basaltos estudados foram gerados a partir de um baixo grau de fusão de uma fonte profunda e enriquecida do tipo OIB. O estudo dos aspectos físicos dos derrames de 1580 juntamente com a petrografia e geoquímica permitiram compreender a história geológica deste evento. / The historic eruption of 1580 A.D. occurred in the southwestern of São Jorge Island, in the central Azores covering a total area of 4 km². This work provides a characterization of the distribution and morphology of the 1580 A.D. lava flows, integrated to petrography and geochemistry. The eruption formed four distinct flows fields: Ribeira do Almeida, Queimada, Ribeira do Nabo I and Ribeira do Nabo II. Detailed geological analysis allowed the identification of spiny, sheet and sllaby pahoehoe and ‘a´ā lava morphotypes. Near the vent, the flow fields are characterized by channelized ‘a´ā flows. With continuous eruption, these lavas flowed downwards forming fan-shaped lava deltas when entering the sea. Sheet pahoehoe flows overlay the ‘a´ā lavas and with continuous inflation the surface of the flows breaks generating slabby pahoehoe surface. The gradual increase in surface fragmentation form rubbly surfaces. In the late stages of the eruption channelized ‘a´ā flows were emplaced, depositing laterally and over the sheet pahoehoe flows. The variations in the lava surface are controlled by the effusion rates and the topography. Petrographically, all lava flows are olivine basalts. The chemistry of the basalts indicate an alkaline nature for the 1580 volcanism. The less-evolved compositions are found in Ribeira do Almeida and this fact can be related to continuous recharge of the magma chamber with more primitive melts. Normalized REE profiles show that the basalts were generated by low volumes of melt of an enriched OIB source. The study of the physical aspects of 1580 lava flows with petrography and geochemistry allowed understand the geologic history of this event.

Page generated in 0.0264 seconds