Dissertations / Theses: 'Volcanic areas'

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Wang, Yunshuen. "Petrology ot Tertiary (?) Volcanic Rocks of Snowville Area, Utah, and Tertiary-Quaternary (?) Volcanic Rocks of Table Mountain and Holbrook Areas, Idaho." DigitalCommons@USU, 1985. https://digitalcommons.usu.edu/etd/3830.

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Basalt flows occur in the Snowville area of north-central Utah and the Table Mountain and Holbrook areas of south-central Idaho. All basalt flows are aphanitic in groundmass, and contain olivine, plagioclase, augite, and opaque oxides. They can be distinguished by texture. Snowville basalt has predominantly subophitic to intergranular textures. Table Mountain basalt is fine grained, with stumpy groundmass plagioclase and equant ilmenite crystals. Holbrook basalt has pilotaxitic to intergranular textures, with the presence of plagioclase phenocrysts and characteristic exsolution lamellae in Fe-Ti oxides. The olivine grains in Holbrook area are intensely oxidized to Fe-Ti oxides. Snowville basalt contains olivine phenocrysts (Fo88 -Fo44 ) in a groundmass of olivine (Fo63 -Fo47), augite (Wo42 -Wo36), and plagioclase (An77-An52). The lower flow unit of Table Mountain basalt contains olivine phenocrysts (Fo88-?) in a groundmass of augite (Wo44 En44 Fs17), and plagioclase (An58-An48). The upper flow unit of Table Mountain basalt has olivine phenocrysts (Fo82-Fo65), plagioclase phenocrysts (An73-An67), and plagioclase groundmass (An64-An55). The Holbrook basalt is composed of olivine phenocrysts (Fo67-Fo57)and plagioclase phenocrysts (An68-An43 ) in a groundmass of olivine (Fo59Fos53) augite (Wo39 En44 Fs17), and plagioclase (An67-An35). The basalts of the Snowville and Holbrook areas, represent petrographic, mineralogical, and chemical characteristics of both olivine-tholeiitic basalt and alkali-olivine basalt, whereas Table Mountain upper and lower flow units show their affinity with alkali-olivine basalt. Chemically, basalts from these three areas are consistently high in silica, magnesium, and alkali content. The Snowville basalt has a high Ba content and high strontium isotope ratio. Fractional crystallization models indicate that the basalt flows from the three different areas are genetically unrelated. The testing also suggests that the upper and lower flow units of the Table Mountain area are not genetically related. The basalts of the three areas also can not be evolved from the basalts found at Kelton, the Rozel Hills or Black Mountain. Basalts of the Snowville area have consistently higher magnesium and silica contents than Snake River basalt, Kelton area basalt, and Rozel Hills and Black Mountain basalt, indicating that they may represent what was initially a very primitive basaltic lava. High Ba content and strontium isotope ratio indicate that the Snowville basalt was contaminated by crustal material. Table Mountain and Holbrook basalt may have formed as a result of partial melting from a pyrolite or garnet peridotite mantle.

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2

Pistorio, Antonio. "Experimental and Computational Approaches to Enhance the Gravimetric Monitoring of Volcanic Areas." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1308.

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The aim of this thesis is to improve the techniques of the gravimetric method, by enhancing the quality of discrete gravity measurements and separating the gravity signals provided by the gravimeters in continuous recording during paroxysmal events, in the gravity field component and the inertial acceleration component to assess the amount of mass redistributed during such events. The preferred scenario for this study is Mt Etna not only because it is the most intensively monitored volcano in the world but also because there was the possibility to perform directly in the field gravity measurements, both discrete and continuous, with the instruments owned by the Istituto Nazionale di Geofisica e Vulcanologia (INGV) - Sezione di Catania - Osservatorio Etneo . In Chapter 1 is described the technical background gravimetric monitoring of active volcanoes in terms of measurements techniques with spring relative and absolute gravimeters. It also discusses on the complexity of the gravity signal and on different gravity contributions that must be quantified in volcanic areas. Finally it presents the existing gravity monitoring network of Mt Etna. In Chapter 2 are shown the results of measurements conducted using two ballistic absolute gravimeters in two different conditions: in dedicated gravity laboratories and in a place used for geophysical studies (volcano monitoring) which present unfavourable environmental conditions (low temperature, high humidity, high ground vibration, etc.). The chosen instruments represent the steady advance in ballistic gravimeter technology: the FG5#238, a commercial instrument produced by the U.S.A. Micro-g LaCoste Inc. and the IMGC-02, developed in Italy by the Istituto Nazionale di Ricerca Metrologica (INRiM) (prototype). Besides, the IMGC-02 is recognized as national standards instrument in Italy and generally the FG5 (family) is more commonly employed for the absolute gravity studies while, specifically, the FG5#238 gravimeter is normally used for different applications from volcano monitoring to the study of gas storage areas. In Chapter 3 was investigated the applicability of combined measurements of absolute and relative gravity as a hybrid method for volcano monitoring, in order to improve the quality of discrete gravity measurements and to achieve a balance between uncertainty and efficiency in gravity measurements. The use of absolute gravimeters in a field survey of the summit area of Mt Etna is unprecedented. Between 2007 and 2009, three hybrid gravity surveys were conducted at Mt Etna volcano, in June 2007, July 2008, and July 2009. Results allowed to increase the knowledge of the dynamics of the volcano through an accurate determination of the position and shape of the volcanic sources. In Chapter 4, to evaluate the coupling degree between inertial acceleration components and the gravity signal provided by spring relative gravity meters, the results of a laboratory tests on a Scintrex CG-3M and on a LaCoste & Romberg model D gravimeters using a vibrating platform to excite them along the x, y and z axes will be explained. For this purpose, to extract the parameters with which to excite the vibrating platform, the seismic signals recorded at two different stations during the 10 April 2011 lava fountain, one of the strongest paroxysmal episode in 2011 eruptive events, were analyzed. Finally, to separate the signal from the gravimeter into gravity field contribute due to the subsurface mass or density variations and the inertial acceleration components due to the ground oscillation, a mathematical approach based on the neural network was also proposed.

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3

GAGLIANO, Antonina Lisa. "Gaseous emissions from geothermal and volcanic areas: focus on methane and methanotrophs." Doctoral thesis, Università degli Studi di Palermo, 2014. http://hdl.handle.net/10447/90855.

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Ogni anno, 22 Tg di CH4 vengono rilasciati in atmosfera da numerose sorgenti sia naturali che antropiche. Il metano riveste un ruolo molto importante nella chimica dell’atmosfera terrestre e nel bilancio dell’energia radiante assorbita, essendo il secondo gas serra più potente dopo la CO2. Le aree vulcaniche e geotermali contribuiscono al flusso di metano in atmosfera, essendo vaste aree di degassamento. Studi preliminari hanno stimato che le emissioni globali di metano dai sistemi geotermali e vulcanici europei sono nel range di 4-16 kt a-1. Questa stima è stata ottenuta indirettamente dai dati delle emissioni di CO2 o H2O e dal rapporto del flusso CO2/CH4 oppure H2O/CH4 misurati nelle principali fumarole. La stima del metano emesso globalmente dalle aree vulcaniche e geotermali non è ancora ben definita in quanto il bilancio tra le emissioni per degassamento dai suoli e il consumo di metano per ossidazione microbica è ancora poco noto. Inoltre, le misure di flusso di metano sono molto difficili da eseguire e si hanno a disposizioni pochi dati. Alcuni metodi, seppur accettabili al fine di ottenere stime sul flusso di metano, escludono completamente la possibilità che il metano venga rimosso per via microbica dai batteri metanotrofi. A scala globale, l’ossidazione microbica del metano contribuisce alla rimozione di circa il 3-9% del metano dall’atmosfera. Ma l’importanza dei batteri metanotrofi è ancora maggiore in quanto questi ossidano la maggior parte del metano prodotto nel suolo e nel sottosuolo prima che questo raggiunga l’atmosfera. Le condizioni ambientali dei suoli vulcanici e geotermali (ad esempio scarso contenuto in ossigeno, alta temperature, attività protonica, ect.) sono stati da sempre considerati inospitali per i batteri metanotrofi. Tuttavia, di recente è stata dimostrata la presenza di batteri acidofili e termofili appartenenti al phylum dei Verrucomicrobia. Questi organismi sono stati individuati alla Solfatara di Pozzuoli (Italia), ad Hell’s gate (Nuova Zelanda) ed in Kamchatka (Russia). Qui riportiamo l’attività metanotrofa riscontrata nei suoli dell’Isola di Pantelleria (Italia), dell’Isola di Vulcano (Italia), di Sousaki (Grecia), di Nea Kameni- Santorini (Grecia), e dell’Isola di Nisyros (Grecia). Evidenze di rimozione microbica del metano in questi suoli era già stata riscontrata nel rapporto dei flussi di CO2/CH4, che risultava sempre inferiore rispetto a quello atteso, indicando una perdita di CH4 durante il suo movimento verso la superficie. Esperimenti per la misura del consumo di metano sono stati eseguiti usando i suoli di Pantelleria, Vulcano, Nea kameni, Nisyros e Sousaki. Questi esperimenti hanno rivelato tassi di consumo fino a 950, 48, 15, 39 e 520 ng CH4 h-1 per ogni grammo di suolo (peso secco), rispettivamente. Solo pochi campioni non hanno indicato consumo di metano. L’analisi dei gas del suolo e le caratteristiche chimico-fisiche del suolo ci hanno permesso di discriminare i fattori principali che influenzano la presenza dei metanotrofi e il tasso dei consumo del metano. La composizione del gas dal suoli, e in particolare il contenuto di CH4 e di H2S rappresentano il fattore discriminate per i metanotrofi. infatti, l’isola d Vulcano e di Nisyros, il cui contenuto in H2S raggiunge circa 250000 ppm, mostrano i consumi più bassi. In aggiunta nei suoli geotermali e vulcanici l’H2S contribuisce all’abbassamento del pH dei suoli. I valori di consuma maggiori sono stati misurati nell’isola di Pantelleria dove l’H 2S è meno di 20 ppm e il pH è vicino alla neutralità. Analisi microbiologiche e molecolari hanno permesso di riscontrare nei suoli di Pantelleria la presenza di batteri metanotrofi affiliati ai Gamma ed agli Alfa-Proteobatteri ed agli acido-termofili Verrucomicrobia. Il metanotrofo coltivabile appartenete al genere Methylocystis (Alfaproteobatterio) e il Gammaproteobatterio Methylobacterium sono stati isolati attraverso colture di arricchimento. Gli isolati mostrano ampi range di tolleranza di pH e temperatura e un tasso di ossidazione fino a 450 ppm/h. Attraverso l’amplificazione del gene pmoA, basandosi sui metodi coltura-indipendenti è stata rivelata un’ampia diversità di batteri metanotrofi appartenenti ai Proteobatteri (α- e γ-) ed ai Verrucomicrobia. Questo è il primo report in cui si dimostra la coesistenza di entrambi i phyla di metanotrofi in un sito geotermale/vulcanico. La presenza dei metanotrofi Proteobatteri era inaspettata perché le condizioni di sito sono state considerate inadeguate e può essere spiegata del pH non eccessivamente basso (>5) di questo specifico sito geotermale. Queste specie possono aver trovato la loro nicchia negli strati più superficiali dei suoli di Favara Grande a Pantelleria dove le temperature non sono così alte ed è presente una forte risalita di metano. capire l’ecologia dei metanotrofi nei siti geotermali e vulcanici aumenterà le conoscenze nel loro ruolo nelle emissioni di metano in atmosfera.
Yearly, 22 Tg of CH4 are released in to the atmosphere from several natural and anthropogenic sources. Methane plays an important role in the Earth’s atmospheric chemistry and radiative balance being the most important greenhouse gas after carbon dioxide. Volcanic/geothermal areas contribute to the methane flux, being the site of widespread diffuse degassing of endogenous gases. Preliminary studies estimated a total CH4 emission from European geothermal and volcanic systems in the range 4-16 kt a-1. This estimate was obtained indirectly from CO2 or H2O output data and from CO2/CH4 or H2O/CH4 values measured in the main gaseous manifestations. The total estimated CH4 emission from geothermal/volcanic areas is still not well defined since the balance between emission through degassing and consumption through soil microbial oxidation is poorly known. Moreover, methane soil flux measurements are laboratory intensive and very few data have been collected until now in these areas. Such methods, although acceptable to obtain order-of-magnitude estimates, completely disregards possible methane microbial oxidation within the soil carried on by the methanotrophs. At the global scale, microbial oxidation in soils contributes for about 3-9% to the total removal of methane from the atmosphere. But the importance of methanotrophic organisms is even larger because they oxidize the greatest part of the methane produced in the soil and in the subsoil before its emission to the atmosphere. Environmental conditions in the soils of volcanic/geothermal areas (i.e. low oxygen content, high temperature and proton activity, etc.) have long been considered inadequate for methanotrophic microorganisms. But recently, it has been demonstrated that methanotrophic consumption in soils occurs also under such harsh conditions due to the presence of acidophilic and thermophilic Verrucomicrobia. These organisms were found in Italy at the Solfatara at Pozzuol (Italy), at Hell’s Gate (New Zealand) and in Kamchatka (Russia), pointing to a worldwide distribution. Here we report on methane oxidation rate measured in Pantelleria Island (Italy), Vulcano Island (Italy), Sousaki (Greece), Nea Kameni (Santorini) and Nisyros (Greece) soils. Clues of methane microbial oxidation in soils of these areas can be already found in the CH4/CO2 ratio of the flux measurements which is always lower than that of the respective fumarolic manifestations indicating a loss of CH4 during the travel of the gases towards earth’s surface. Laboratory methane consumption experiments made on soils collected at Pantelleria, Vulcano, Nea Kameni, Nysiros and Sousaki revealed for most samples consumption rates up to 950, 48, 15, 39 and 520 ng CH4 h-1 for each gram of soil (dry weight), respectively. Only few soil samples displayed no methane consumption activity. Analysis on soil gases and chemical-physical characteristics of the soils allowed us to discriminate the main factors that influenced the methanotrophs presence and the methane consumption rate. Soil gases composition, and in particular the amount of the CH4 and H2S, represent the main discriminating factor for methanotrophs. In fact, Vulcano and Nisyros Island, whose soil gas contained up to 250000 ppm of H2S, showed the lowest consumption rate. Moreover, in geothermal/volcanic soils H2S contribute to the soil pH lowering; highest methane consumption were recorded in Pantelleria island were H2S is less than 20 ppm and pH close to the neutrality were measured. Microbiological and molecular analyses allowed to detect the presence of methanotrophs affiliated to Gamma and Alpha-Proteobacteria and to the newly discovered acido-thermophilic methanotrophs belong to the Verrucomicrobia phylum in soils from Pantelleria. Culturable methanotrophic Alphaproteobacteria of the genus Methylocystis and the Gammaproteobacteria Methylobacterium were isolated by enrichment cultures. The isolates show a wide range of tolerance to pH and temperatures and an average methane oxidation rate up to 450 ppm/h. A larger diversity of (α- and γ-) proteobacterial and verrucomicrobial methanotrophs was detected by a culture-independent approach based on the amplification of the methane mono-oxygenase gene pmoA. This is the first report describing coexistence of both the methanotrophic phyla (Verrucomicrobia and Protebacteria) in the same geothermal site. The presence of proteobacterial methanoptrophs, in fact, was quite unexpected because they are generally considered not adapted to live in such harsh environments and could be explained by not really low pH values (> 5) of this specific geothermal site. Such species could have found their niches in the shallowest part of the soils of Favara Grande were the temperatures are not so high and thrive on the abundant upraising methane. Understanding the ecology of methanotrophy in geothermal sites will increase our knowledge of their role in methane emissions to the atmosphere.

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Strauss, Simon Yale. "Marginal protection : sustainable development, social resilience and migration within natural protected areas of the Trans-Mexican Volcanic Belt, central Mexico." Thesis, McGill University, 2006. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=99609.

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Natural protected areas are places intended to protect nature, but it is now accepted that their social impact must be compatible with the ideals of 'sustainable development': they must conserve nature while improving, or at least not injuring, the socio-economic status of human communities. In Mexico, recent conservation policy has emphasized the creation of biosphere reserves, a type of protected area designed as a practical application of the concept of sustainable development. Previous research has shown that in Mexico and elsewhere, such reserves are often created in areas that are environmentally marginal and where, therefore, the lives and livelihoods of inhabitants are precarious at best. This makes the dual challenges of protecting nature and aiding social and economic development particularly acute. This study explores these challenges by considering the socio-economic patterns within protected areas along the Trans-Mexican Volcanic Belt of central Mexico. The study measured sustainable development, as indexed by the Mexican government, at both the regional and local scales, combining census data and interviews with residents in the Sierra Gorda Reserve. This combination of methodologies allowed for a fuller description of the social impacts of protected areas at different scales. The study found that while overall the lives of residents in or near natural protected areas improved steadily between 1990 and 2000, these areas are also characterized by high migration levels and an aging population, which may threaten the future sustainability of these communities. The study concludes by suggesting that migration is a key factor which should be included in Mexico's assessments of sustainable development, and that the concept of a community's social resilience is extremely useful in informing future studies.

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5

Corcoran, Patricia Lynn. "Physical volcanology, geochemistry, and tectonic evolution of three selected areas in the Point Lake and Beaulieu River volcanic belts, Slave Province, Northwest Territories, Canada." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp05/NQ66650.pdf.

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Christianson, Amy Nadine. "Assessing and improving the effectiveness of staff training and warning system response at Whakapapa and Turoa ski areas, Mt. Ruapehu." Thesis, University of Canterbury. Geological Sciences, 2006. http://hdl.handle.net/10092/1271.

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Ruapehu is an active volcano located on the North Island of New Zealand, with the most recent major eruptions occurring in 1945, 1969, 1975, and 1995/96. Ruapehu is also home to the three major North Island ski areas, Whakapapa, Turoa, and Tukino. Because of the high frequency of eruptions, there is a significant volcanic hazard at the ski areas particularly from lahars which can form even after minor eruptions. Most recently, lahars have affected Whakapapa ski area in 1969, 1975, and 1995/96. The most significant risk at Turoa is from ballistic bombs due to the proximity of the top two T-Bars to the crater. Ash fall has also caused disruption at the ski areas, covering the snow and causing damage to structures. There is yet to be a death at the ski areas from a volcanic event; however the risk at the ski areas is too high to be completely ignored. The ski areas at Whakapapa and Turoa are currently operated by Ruapehu Alpine Lifts (RAL), who have been significantly improving their commitment to providing volcanic hazard training for their staff and preparing for handling a volcanic eruption. RAL is joined by the Institute of Geological Sciences (GNS) and the Department of Conservation (DoC) in trying to mitigate this risk through a range of initiatives, including an automated Eruption Detection System (EDS), linked to sirens and loudspeakers on Whakapapa ski areas, as well as by providing staff training and public education. The aim of this study was to provide RAL with recommendations to improve their staff training and warning system response. Staff induction week at both Turoa and Whakapapa ski areas was observed. Surveys were distributed and collected from staff at both ski areas, and interviews were conducted with staff at Whakapapa ski area. Data obtained from staff interviews and surveys provided the author with insight into staff's mental models regarding a volcanic event response. A simulation of the warning system was observed, as well as a blind test, to collect data on the effectiveness of training on staff response. Results indicated permanent and seasonal staff were knowledgeable of the volcanic hazards that may affect the ski areas, but had differing perspectives on the risk associated with those hazards. They were found to be confident in the initial response to a volcanic event (i.e. move to higher ground), but were unsure of what would happen after this initial response. RAL was also found to have greatly improved their volcanic hazard training in the past year, however further recommendations were suggested to increase training effectiveness. A training needs analysis was done for different departments at the ski areas by taking a new approach of anticipating demands staff may encounter during a volcanic event and complementing these demands with existing staff competencies. Additional recommendations were made to assist RAL in developing an effective plan to use when responding to volcanic events, as well as other changes that could be made to improve the likelihood of customer safety at the ski areas during an eruption.

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Okubo, Ayako. "Studies on geomagnetic spatial and temporal variations in volcanic area." 京都大学 (Kyoto University), 2005. http://hdl.handle.net/2433/145088.

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Kyoto University (京都大学)
0048
新制・課程博士
博士(理学)
甲第11320号
理博第2878号
新制||理||1430(附属図書館)
22963
UT51-2005-D71
京都大学大学院理学研究科地球惑星科学専攻
(主査)教授田中良和, 教授大志万直人, 教授鍵山恒臣
学位規則第4条第1項該当

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Spedalieri, Giancarlo. "Unravelling volcanic tremor source at mount etna from quantitative multiparametric analysis and moment tenso inversion." Doctoral thesis, Università di Catania, 2019. http://hdl.handle.net/10761/4134.

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UNRAVELLING VOLCANIC TREMOR SOURCE AT MOUNT ETNA FROM QUANTITATIVE MULTIPARAMETRIC ANALYSIS AND MOMENT TENSOR INVERSION Developments of multiparametric monitoring networks, real time analysis techniques and the acquisition of high-resolution data, have allowed to improve the knowledge of the structures and dynamics that characterize the active volcanoes. To understand the dynamics of an active volcano, it is possible to proceed with two different types of studies: i) multiparametric studies based on the joint analysis of different data (such as geophysical, geochemical, petrological data); ii) detailed studies concerning specific data. In order to understand source volcanic tremor at Mt. Etna volcano, volcanic tremor recorded during the vigorous summit of 2011-2012 was analyzed. In particular, this thesis shows the results obtained from the investigation of the volcanic tremor source through a duplex study: i) a multiparametric study based on the quantitative comparison between different time series such as volcanic tremor amplitudes and geochemical data such as soil CO2 flux and the SO2 flux at summit craters; ii) a moment tensor inversion analysis of volcanic tremor recorded during a lava fountain episode of the considered period. For these studies, data acquired from the multiparametric monitoring network managed by Istituto Nazionale di Geofisica e Vulcanologia were used.The quantitative comparison between seismic and geochemical data was performed in order to identify and quantitatively estimate similar trends variations between the compared time series, both synchronous and characterized by time lags. To this end, four different analysis techniques have been implemented, such as Cross-Correlation, Randomized Cross-Correlation, wavelet analysis and linear regression. The obtained results allowed to infer pressurization and depressurization dynamics of the plumbing system during the different eruptive phases observed during the considered period. The moment tensor inversion analysis of the volcanic tremor recorded at Mt. Etna represents a novelty. Specifically, this analysis was applied to volcanic tremor recorded during the lava fountain episode that occurred on 5 August 2011, one of the most vigorous of the 25 episodes that characterized the 2011-2012 period. The results allowed to highlight a source mechanism generated by a sub-horizontal crack near the summit crater area, which can be interpreted as a valve through which gas-rich magma is ejected during the lava fountain activities.

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Leahy, Kevin. "The geology of kimberlites from the Fort a la Corne area, Saskatchewan, Canada." Thesis, University of Leeds, 1996. http://etheses.whiterose.ac.uk/283/.

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Kimberlites have been recently discovered beneath 100m of glacial sediment at Fort a la Come, Saskatchewan, Canada. Crater and extra-crater facies have been intersected in borehole core, interstratified with coastal and marine sediments of Cretaceous age. Extra-crater kimberlite is very rare, and particularly well preserved at Fort a la Come. It is encountered in five borehole intersections drilled by Rhonda Mining Corporation, sponsors of the Operation Fish Scale project, which included kimberlite research at the University of Leeds. The regional setting and geological description of six kimberlite borehole intersections are presented. In addition, the broad geodynamic conditions and the stratigraphic context are described, and from these a model for kimberlite eruption is constructed. The kimberlites are then described at a range of scales from stratal thickness and disposition, to ultra-fine diagenetic mineral growth. A textural classification is then applied to the deposits. The volcanology of the Fort a la Cone kimberlites are then discussed: these are unusual in that the craters are preserved, and are broad and flat, rather than steep sided tapering cones. A new term, pateran crater, and process of evolution is proposed for these and other kimberlites of similar morphology. The survival of these volcanic edifices in the sedimentary environment is also considered. The geochemistry of the kimberlites is presented, both bulk rock, and over 450 analyses of individual mineral grains by electron microprobe. These minerals are mostly gamet, ilmenite and pyroxene, of megacryst, kimberlite, crust, mantle peridotite and eclogite origin. The mineral chemistries are compared to those found in other kimberlites around the world, and the nature of the cratonic lithosphere is described. The P-T and compositional characteristics of the lithosphere are further refined from diamond and garnet trace element chemistry in collaborative works with Taylor and Griffin, described herein. Economic aspects of the kimberlites are reviewed, and all the conclusions are presented in time order, from diamond growth in the Archean, crustal evolution in the Mid-Proterozoic, Early Cretaceous magma generation and eruption, to Late Cretaceous reworking and burial.

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Thorkelson, Derek John Carleton University Dissertation Geology. "Volcanic and tectonic evolution of the Hazelton group in Spatsizi river (104H) map-area, north-central British Columbia." Ottawa, 1992.

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11

Davarpanah, Armita. "Magmatic Evolution of the Eocene Volcanic Rocks of the Bijgerd Kuh E Kharchin Area, Uromieh-Dokhtar Zone, Iran." Digital Archive @ GSU, 2009. http://digitalarchive.gsu.edu/geosciences_theses/19.

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Composition and texture of the Middle and Late Eocene volcanic, volcaniclastic, and volcanic-sedimentary rocks in the Bijgerd-Kuh e Kharchin area, in the Uromieh-Dokhtar zone northwest of Saveh, Iran, suggest the complexity of the magmatic system that involved multiple eruptions from one or more sources. Hydrated volcanic fragments in hyaloclastic rocks, and the presence of a sequence of shallow and intermediate-depth marine microfossils, suggest that the Middle Eocene units were erupted in a marine basin. The bimodal volcanism of the Late Eocene is distinguished by the presence of four alternating sequences of hyaloclastite lava and ignimbrite. The REE patterns show spatial homogeneity and temporal heterogeneity in the composition of all the Late Eocene sequences, suggesting origination of magma from varying sources that erupted at different times. The trace element distributions of the hyaloclastites and ignimbrites are compatible with those evolved through fractional crystallization of the lower and upper continental crust, respectively.

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Barton, David J. "Frequency-magnitude distribution and spatial fractal dimension of seismicity at The Geysers geothermal area and Long Valley Caldera, California." Thesis, Durham University, 1998. http://etheses.dur.ac.uk/5046/.

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Although there is no obvious reason why seismic 6-value and the spatial fractal dimension of earthquakes, D, should be related, there are several reports of observed empirical correlations between these two quantities. In order to investigate this phenomenon, and attempt to relate it to different types of earthquakes, industrially induced seismicity in The Geysers geothermal area, California and earthquake swarms in Long Valley caldera, California were analysed. Raw seismograms from the Unocal-NEC-Thermal network in The Geysers were processed automatically, calculating magnitudes from coda lengths and locating them using a three-dimensional velocity model. Seismicity correlated with the locations of commercial wells and surface fault locations. The entire Geysers dataset was too complex for clear correlations between b, D, seismicity and injection to be observed. In several cases, short pulses of injection induced bursts of seismicity of either small-magnitude, clustered events or large-magnitude diffuse seismicity, resulting always in a transient anomaly of negative b/D. However, sometimes pulses of injection were not accompanied by b/D transients and sometimes b/D transients were not accompanied by known injection. The latter cases may or may not indicate undisclosed injection activity. A seismic crisis in Long Valley caldera was associated with major b/D anomalies that accompanied migration of the activity from a hydrothermal zone on the south edge of the resurgent dome to the right-lateral, blind, near-vertical South Moat fault to the immediate south. The results indicated that the hydrothermal zone is an inhomogeneous structure whereas the South Moat has a mature, coherent fault plane, capable of generating magnitude M = 6 earthquakes and posing a threat to the town of Mammoth Lakes.

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Gunning, Michael H. "Definition and interpretation of Paleozoic volcanic domains, northwestern Stikinia, Iskut River Area, British Columbia." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21289.pdf.

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Njilah, Isaac Konfor. "Geochemistry and petrogenesis of tertiary-quaternary volcanic rocks from Oku-Ndu area, N.W. Cameroon." Thesis, University of Leeds, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.305536.

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15

Cafaggi, Sara. "Temporal and geochemical characterization of the Negros de Aras (northern Chile) monogenetic volcanic field." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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Negros de Aras is a monogenetic volcanic field located in the Central Volcanic Zone of the Andes in northern Chile, 26 km towards the north from active Socompa volcano, at a zone dominated by N-S trending faults. It is formed by lava flows and subordinate scoria cone, dated between < 1.5 and 0.6 ± 0.4 Ma, referable to six formations. Geochemically, lava flows display a range from 54.28 to 64.47 wt.% SiO2, respectively and show a compatible trending of major elements as Fe2O3, TiO2, MgO, whereas K2O and Na2O present an incompatible trending. Trace elements display elevated Sr/Y and La/Yb ratios, high Sr values, depleted Y and HREE values, absence of an Eu anomaly, Nb and Ti negative anomalies, and relative enrichment LILE and LREE. The geochemical features suggest that the magma has fractionated garnet ± amphibole in its origin, with a low degree of contamination during its ascents to the surface. Besides, considering the small-volume magma batches, it is possible to suggest that the magmas did not have any prolonged stopping on the ascent to the surface. The content of volatiles dissolved, and the ascent rate of these magmas played an essential role in the definition and the change of dominant eruptive styles.

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16

Milluzzo, Vincenzo. "Seismic chacterization of Vulcano island and Aeolian area by tectonic and seismo-volcanic events." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1330.

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We investigated the relationship between seismo-volcanic events, recorded at La Fossa crater of Vulcano (Aeolian Islands, Italy) during 2004-2009, and the dynamics of the hydrothermal system. During the period of study, six episodes of increasing numbers of seismo-volcanic events took place at the same time as geothermal and geochemical anomalies were observed. These geothermal and geochemical anomalies have been interpreted as resulting from an increasing deep magmatic component of the hydrothermal fluids. Four classes of seismic events (long period, high frequency, monochromatic and tornillos events), characterised by different spectral content and various similarity of the waveforms, have been recognised. These events, clustered mainly below La Fossa crater area at depths of 0.5 1.1 km b.s.l., were space-distributed according to the classes. Based on their features, we can infer that such events at Vulcano are related to two different source mechanisms: (1) fracturing processes of rocks and (2) resonance of cracks (or conduits) filled with hydrothermal fluid. In the light of these source mechanisms, the increase in the number of events, at the same time as geochemical and geothermal anomalies were observed, was interpreted as the result of an increasing magmatic component of the hydrothermal fluids, implying an increase of their flux. Indeed, such variation caused an increase of both the pore pressure within the rocks of the volcanic system and the amount of ascending fluids. Increased pore pressures gave rise to fracturing processes, while the increased fluid flux favoured resonance and vibration processes in cracks and conduits. Finally, a gradual temporal variation of the waveform of the hybrid events (one of the subclasses of long period events) was observed, likely caused by heating and drying of the hydrothermal system. After careful analysis of the seismo-volcanic events of the Aeolian Islands area, the attention was paid to the tectonic events, in order to find possible relationships with the volcanic activity in the area. The aim of this part of the thesis was to identify spatial clusters of earthquakes, locate active seismogenic zone and their relationships with the volcanic activity in the Aeolian Islands. High precision locations were performed in the present thesis, by applying the concept of the velocity model-hypocentres joint inversion and earthquake relocations, along with an analysis of the fault plane solutions. In order to improve our knowledge on the active seismo-tectonics areas we exploited a dataset encompassing 351 events recorded during a 17 year period (1993-2010). Overall, our results show that part of the seismicity is clustered along active seismogenic structures that concur with the main regional tectonic trends whose activity furnishes new elements to better understand the dynamics of the area. A cluster of 24 events in the northern part of Vulcano, NE-SW oriented, marks the presence of a structure that seems to play a key role in magma uprising at Vulcano. These earthquakes suggest the existence of a seismogenic structure (passing just below Vulcanello), which could be interpreted as a discontinuity linking the two magma accumulation zones, thereby representing a possible preferential pathway along which magma may intrude as well as being responsible for fluid migration toward the surface. The results presented in this thesis suggest that the comparison of seismic, ground deformation and temperature data can be useful for better understanding the dynamics of a complex volcano-hydrothermal system, including a better definition of the origin of a volcano unrest, and hence for improving the estimation of the level of the local volcanic hazard.

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17

Malandrino, Pasqualino. "Il cancro tiroideo in Sicilia: rischio ambientale vulcanico." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1577.

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Introduzione: L'aumentata incidenza del cancro tiroideo in diverse aree vulcaniche suggerisce una potenziale relazione tra l'ambiente e la contaminazione dei residenti con sostanze chimiche vulcaniche che hanno un effetto cancerogeno sulla tiroide. Disegno dello studio: abbiamo sviluppato tre fasi: 1) studio epidemiologico: paragone dell incidenza del cancro tiroideo nell area vulcanica dell Etna con quella di un area di controllo non vulcanica.; 2) studio ambientale: paragone delle concentrazioni di metalli pesanti e oligoelementi nelle acque del sistema acquifero dell Etna e dell area di controllo non vulcanica in Sicilia; 3) studio biologico: paragone delle concentrazioni di metalli pesanti e oligoelementi nelle urine dei residenti nell area vulcanica e dell area di controllo in Sicilia. Metodi: i dati di epidemiologia del cancro tiroideo sono stati estrapolati dal Registro Regionale Siciliano per il Cancro della Tiroide (periodo 2002-2006). In totale, 34 oligoelementi sono stati misurati nelle acque e nelle urine di 278 adulti residenti nell area vulcanica (n = 140 ) e nell area di controllo (n = 138). Risultati: l'incidenza del cancro tiroideo era superiore nella zona vulcanica (tasso di incidenza standardizzato per l età della popolazione mondiale= 18.5/105 vs 9.6/105 nella zona di controllo). Tale differenza era esclusivamente sostenuta da una maggiore incidenza di cancro tiroideo di istotipo papillare. Nella zona vulcanica i tumori erano più frequentemente multifocali e con estensione extratiroidea (p < 0.01). Gli elementi studiati sono stati trovati ad una concentrazione significativamente maggiore sia nelle acque che nelle urine dei residenti nell area vulcanica, suggerendo la possibilità di una biocontaminazione. In quest area le concentrazioni urinarie di Boro, Molibdeno, Tungsteno e Palladio erano superiori ai valori di riferimento per l Italia in oltre il 20% dei campioni analizzati. Conclusioni: nell area vulcanica dell Etna, caratterizzata da un elevata incidenza di cancro tiroideo, le concentrazioni di diversi oligoelementi e metalli pesanti sono significativamente aumentate nelle acque e nelle urine dei residenti. Questa associazione è compatibile (ma non dimostra) con una relazione di causa - effetto tra una o più di queste sostanze chimiche di origine vulcanica e il cancro tiroideo.

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18

So, Chak-tong Anthony, and 蘇澤棠. "Petrology and geochemistry of volcanic rocks of the Lantau Peak Area, Lantau Island, Hong Kong." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31221646.

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19

Arslan, Mehmet. "Mineralogy, geochemistry, petrology and petrogenesis of the Meydan-Zilan (Ercis-Van, Turkey) area volcanic rocks." Thesis, University of Glasgow, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437611.

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20

Bowen, Michael Peter. "The petrogenesis of the volcanic rocks of the Witwatersrand triad in the Klerksdorp area, Transvaal." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1001569.

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Several hundred chemical analyses of early Proterozoic lavas of the Witwatersrand triad (incorporating the Dominion Group, Witwatersrand Supergroup and Ventersdorp Supergroup) in the Klerksdorp area, have revealed the presence of various distinct magma types. These essentially correspond to formally defined lithostratigraphic units, but several inconsistencies have necessitated the use of informal nomenclature. The lavas have been regionally metamorphosed to low-grade, greenschist facies assemblages. Original igneous textures are preserved, despite a metamorphic overprint. Metamorphism has resulted in a certain degree of random chemical remobilization. Ba, Sr, Rb, K₂0, Na₂0 and CaO have been highly mobile, and their usefulness in petrogenetic modelling is extremely limited. In contrast, Zr, Nb, Y, LREE's, Cr, Ni, Ti0₂ P₂0₅ and Al₂0₃ have remained immobile. Ti/Zr and Ti/P ratios together constitute efficient discriminating variables for characterizing the different magma types. Lava compositions range from primitive Mg-rich tholeiites to rhyolites, the bulk being tholeiitic andesites. Al₂0₃ contents do not exceed 15%, a feature which reflects the tholeiitic, as opposed to calcalkaline, character of these lavas. Two magma-types are present within the Dominion Group, which is a typical example of bimodal volcanism. The Dominion basic lavas are overlain by the Dominion acid porphyries, with a limited amount of interfingering. The basic lava suite is highly fractionated, with compositions ranging from Mg-, Cr- and Ni-rich tholeiites (close to primary mantle melts) to evolved tholeiitic andesites. The most primitive liquids evolved by 45% fractional crystallization of hornblende, followed by a further 70% crystallization of an orthopyroxene-plagioclase assemblage containing up to 3% sulphides. The Dominion porphyries are rhyolitic, display very limited compositional variation, and probably represent a crustal melt related to the same magmatic event which produced the basic lavas. The only lavas from the Witwatersrand Supergroup present in the Klerksdorp area are those of the Crown Formation (Jeppestown amygdaloid). These are tholeiitic dacites which display extremely limited compositional variation, and are unrelated to any of the other magmas of the Witwatersrand triad. The Ventersdorp Supergroup comprises 4 magma-types: The Kliprivierberg Group lavas at the base are subdivisible into 3 sub-types on the basis of Zr contents. (Zr>11Oppm) are the most evolved. They are tholeiitic andesites which display fairly limited compositional variation. It is likely that more evolved compositions are present in other areas where the porphyritic lavas which characterize this unit are better developed. The overlying Orkney lavas are characterized by 110ppm>Zr>90ppm. They are tholeiitic andesites of similar composition to the Alberton lavas, but have lower incompatible element levels, higher siderophile element levels, and are of extremely uniform composition. The uppermost Loraine/Edenville lavas range from magnesian tholeiites to tholeiitic andesites. They are distinguished by Zr< 90ppm, and contain the most primitive magmas af the Witwatersrand triad, with up to 17,5% MgO, 2600ppm Cr, 600ppm Ni and M-values up to 77. The most primitive liquids evolved by 38% fractional crystallization of orthopyroxene ∓ chromite, followed by 35% fractional crystallization of an extract containing clinopyroxene and plagioclase. The absence of olivine precipitation is a result of the inherently high Si0₂ content of the magma. The Loraine/Edenville, Orkney and Alberton lavas do not lie on a common liquid line of descent, but are probably consanguinous. The Platberg Group overlies the Kliprivierberg Group, and has a coarse-clastic sedimentary unit, the Kameeldoorns Formation, at the base. Three petrographically distinct porphyritic lava sequences overlie the Kameeldoorns Formation, namely the informal "Goedgenoeg formation", the Makwassie quartz-feldspar porphyries and the Rietgat Formation. Despite petrographic differences, the Goedgenoeg and Rietgat lavas are chemically indistinguishable and thus form a single magma-type. The Makwassie porphyries are dacitic in composition with a high proportion of feldspar and quartz phenocrysts. Rational variation trends are attributed to a nett loss of Si0₂ during secondary alteration. The porphyries are probably of crustal origin. The Goedgenoeg/Rietgat lavas display unusual chemistry and a broad, irrational compositional spectrum. They contain very high incompatible element levels, high nonnative quartz, as well as high MgO, M-values, Cr and Ni relative to the other tholeiitic andesites of the Witwatersrand triad. It is tentatively suggested that they are hybrid magmas containing both crust and mantle components, the former possibly represented by the Makwassie porphyries. Field evidence suggests that Platberg volcanism commenced directly after Klipriviersberg volcanism ceased, and was accompanied by a period of enhanced tectonic activity. The Platberg lavas thus probably reflect a crustal melting cycle associated with the Klipriviersberg magmatic event. The Allanridge lavas are the youngest rocks of the Witwatersrand triad. They are separated from the Platberg Group by a unit of flat-lying sediments, the Bothaville Formation, which was deposited after an extended period of peneplanation. The Allanridge lavas form a separate magma-type. They are tholeiitic andesites of similar composition to the Alberton lavas, but have higher incompatible element levels and are not consanguinous. The compositional similarities amongst the basic magma-types of the Witwatersrand triad suggests that all were generated in an hydrous mantle. Interelement ratio differences between the various magma-types nevertheless support the concept that the mantle was chemically heterogeneous during the early Proterozoic.

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21

So, Chak-tong Anthony. "Petrology and geochemistry of volcanic rocks of the Lantau Peak Area, Lantau Island, Hong Kong /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21375549.

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22

Aranzulla, Massimo. "Atmospheric water vapour tomography for DInSAR application and effect of volcanic plume on the microwaves." Doctoral thesis, Università di Catania, 2014. http://hdl.handle.net/10761/1543.

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A particular synergy among GPS and SAR techniques, to improve the precision of the current ground deformation monitoring techniques,is investigated. The study of atmospheric anomalies in the GPS EM waves propagation is useful to extrapolate information about the wet refractivity ?eld. Because of its height and the quite variable weather conditions, the estimation of Mount Etna atmospheric anomalies using GPS measurements have noticeable importance to calibrate the SAR interferograms and to establish the effective ground deformation of the volcanic edifice. In this study we presented a method to obtain a 3D electromagnetic waves velocity tomography, starting from the GPS output data analysis. Thanks to the agreement between the University of Catania and the INGV-OE, the GPS data used in this work come from Etnanet framework. The GPS processing has been carried out by using the GAMIT software, by adopting appropriate processing parameters. A new software was developed for deriving the tropospheric tomography from the GPS data. The code was validated by using synthetic tests which assume different structure of atmospheric anomalies and with random noise about twice severe than the typical errors of the GPS. The results of the tests proved that the tomography software is able to reconstruct the simulated anomalies faithfully. The code was applied to study the structure of the atmosphere in an actual case: the period of August 12, 2011 at 10.00 am. The results of the tomography indicate clearly important features of the refractivity field of the studied day. In conclusion, the synthetic tests and the application on actual data sets of the new software demonstrate that it is able to reveal the tropospheric anomalies and thus it is an useful tool to improve the results of the SAR interferometry. An indirect outcome of the use of the GPS for the atmospheric sounding on an active volcanic area is that concerning the detection of volcanic products in the atmosphere. Due to the Mt. Etna persistent activity occurred during the last two years, the capability of GPS to detect the volcanic plume was investigated. The Etna volcano is particularly suited for an in-depth investigation into the aptitude of GPS observations to detect volcanic plumes, owing to both the high frequency of explosive episodes and also the well-developed GPS network. Two di?erent approaches were tested, in order to examine the capability of the GPS network to detect volcanic plumes at Etna. The ?rst approach is applied on the signal strength of the GPS L2 carrier phase data, the second approach, instead, is statistical, and analyzes the single di?erence post ?t residual of elaboration signals to assert the hypothesis that the plume a?ects the GPS data. The proposed method has been tested for the September 4 5, 2007 activity of Mt. Etna. Results from nineteen GPS permanent stations show that during this explosive activity, the GPS residuals definitely include the contribution of the volcanic plume. In the future, data derived from the GPS stations located on Etna's flanks could be used to improve the alerting system of volcanic ash, already operating at the Istituto Nazionale di Geofisica e Vulcanologia, Osservatorio Etneo.

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23

Pan, Jason J. "A geological and geochemical transect of the volcanic stratigraphy in the D'Alembert-Cléricy area, Noranda, Québec /." Thesis, McGill University, 1993. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=69648.

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The Archean rocks in the D'Alembert-Clericy area of the Noranda district were mapped along a transect across stratigraphy. Located within the youngest part of the Blake River Group, this six km thick volcanic assemblage trends northwest, youngs northeast, and has increasing dip from $ sim$45$ sp circ$ in the west to subvertical in the east, with some folding within the sequence.
Chemostratigraphic units were established using Zr/Y, La$ sb{ rm N}$/Yb$ sb{ rm N}$, and other immobile and incompatible HFSE ratios, and AFM and Miyashiro major element plots. Lithogeochemical technique based on the HFSE and other immobile and incompatible elements have been applied to both fresh and altered rocks; the trace element parameters are more specific than the major element discriminants.
The stratigraphy along the D'Alembert-Clericy transect is subdivided into three major chemostratigraphic units: Lower Transitional Series, Middle Tholeiitic Series, and Upper Mixed Tholeiitic-Transitional Series. Overall, the lithologies comprise $ sim$65% tholeiitic and $ sim$35% transitional volcanics. The tholeiites are mainly represented by basalts and rhyolites, whereas the transitional rocks are mostly andesites and rhyolites.
The geological, stratigraphic, and lithochemical attributes along the transect indicate the potential for massive sulfide deposits is comparable to that of the Central Mine Sequence. Although the thesis area contains a greater proportion of basalts and volcaniclastic material than the Central Mine Sequence, both areas contain major tholeiite basalt-rhyolite bimodal sequences, several thick felsic units, and andesite-rhyolite transitional suites.

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24

Bowen, Teral Barbara. "The geochemical stratigraphy of the volcanic rocks of the Witwatersrand triad in the Klerksdorp area, Transvaal." Thesis, Rhodes University, 1985. http://hdl.handle.net/10962/d1004932.

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This study lias initiated with the aim of identifying the existence of any geochemical criteria which may be used to distinguish between the various volcanic formations within the Witwatersrand triad. The Witwatersrand triad comprises three sequences: the Dominion Group at the base, the Witwatersrand Supergroup in the middle, and the Ventersdorp Supergroup at the top. It is underlain by Archaean basement rocks, and covered by rocks of the Transvaal sequence. The Dominion Group consists of the sedimentary Rhenosterspruit quartzite Formation at the base, overlain by a bimodal component of the Syferfontein Porphyry succession of lavas. Basaltic lavas are the major component of the Rhenosterhoek Formation, while the overlying Formation consists primarily of dacitic porphyries. Intercalations of one lava type within the other are common, however, so each formation is not the exclusive domain of only one lava type. The Witwatersrand Supergroup, a predominantly argillaceous and arenaceous sequence, contains two narrow volcanic horizons, one of wbich, the Jeppestown Amygdaloid (now Crown Formation), consisting of tholeiitic andesites, occurs in the study area. The overlying Ventersdorp Supergroup has, at its base, the basaltic Klipriviersberg Group, of which four out of six formations are present in the study area, namely, the Alberton, Orkney, Loraine and Edenville Formations. This group is succeeded unconformably by the PIatberg Group, consisting of the sedimentary Kameel doorns Formation, followed by the (informal) Goedgenoeg, Makwassie Quartz Porphyry and Rietgat Formations. The Goedgenoeg and Rietgat Formations are basaltic, whil e the Mawassie rocks range from basaltic to dacitic, the majority being tholeiitic andesites and andesites . The Pniel sequence at the top of the Ventersdorp Supergroup consists of the sedimentary Bothaville Formation, and the Allarridge Formation, the lavas of which are basaltic with some andesitic tendencies. A well-defined geochemical stratigraphy was found to exist. From the eleven volcanic formations examined, nine distinct geochemical units emerged, as the Loraine and Edenville Formations were found to have the same geochemical characteristics, as did the Goedgenoeg and Rietgat Formations. Despite having undergone law-grade greenschist facies metamorphism, very clear variation patterns with height are displayed by the immobile elements Ti, P, Kb, Zr and Y, and the light rare earth elements La, Ce and Nd. In contrast, much scatter was observed in the variation patterns of Na, K, Mn, Ba and Rb. Three techniques were employed to effect discrimination between formations - orthosonal discrimination, interelement and ratio vs ratio plots, and discriminant analysis. Confidence limits placed on normal probability plots served to isolate outlier samples for further examination by the various discrimination techniques. A successful test of the efficacy of the discrimination techniques was afforded when fourteen samples from an unknown succession were positively identified as representative of the Klipriviersberg Group

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25

Camire, Genevieve Carleton University Dissertation Geology. "Volcanic stratigraphy in the Hunter Creek Fault area, east of the Flavrian Pluton, Rouyn-Noranda, Quebec." Ottawa, 1989.

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26

Paradis, Suzanne Carleton University Dissertation Geology. "Stratigraphy, volcanology and geochemistry of the New Vauze - Norbec area, Central Noranda Volcanic Complex, Quebec, Canada." Ottawa, 1990.

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27

Hickson, Catherine Jean. "Quaternary volcanism in the Wells Gray-Clearwater area, east central British Columbia." Thesis, University of British Columbia, 1986. http://hdl.handle.net/2429/27315.

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Basaltic volcanism in the form of small-volume, subaerial and subaqueous eruptions have occurred in the Wells Cray—Clearwater area of east central British Columbia. These eruptions have been dated by the K-Ar method and by relationships to dated glaciations. The oldest known eruption may be as old as 3.2 Ma, but is more likely 2 Ma or less. The youngest eruptions are less than 7560 ± 110 radiocarbon years. The most extensive basalts are valley-filling and plateau-capping flows of the Clearwater unit, which are Pleistocene in age and greater than 25 km³ in volume. The deposition of flows of the Clearwater unit has overlapped at least three periods of glaciation. The interaction of glacial ice and basaltic magma has been recorded in the form of tuyas, ice ponded valley deposits and subglacial mounds (SUGM). In a few place glacial till has been preserved beneath basalt flows. Flows of Wells Gray—Clearwater suite appear to have erupted from vents that are both spatially and temporally separated. The individual eruptions were of low volume (<1km³) and chemically distinct from one another. Major element composition is variable but the lavas are predominantly alkalic. Olivine is the predominant phenocryst phase. Plagioclase and augitic clinopyroxene rarely occur as phenocrysts, but both minerals are ubiquitous in the groundmass. Orthopyroxene was not seen in any of the samples. Flows appear to have erupted with minimal crystal fractionation or crustal contamination. The range of compositions seen in the suite is best explained by a process of partial melting and the progressive depletion of the mantle source by earlier melts. Progressive depletion of the mantle source was coupled with enrichment of parts of the mantle in K as well as some lithophile and siderophile elements. Increasing alkali content may have triggered the highly enriched eruptions of Holocene age that, despite very low degrees of partial melting, were capable of reaching the surface. Overprinting the effects of partial melting are inherited heterogeneities in the source zone of the magmas. Based on whole-rock chemistry the magma source appears to be a highly depleted region similar to that which produces the most depleted mid-ocean ridge basalts (MORB). The zone is, however, capable of producing large volume (≃ 15%) partial melts and has not been isotopically depleted to the same extent as MORB source regions. Isotope analyses of ⁸⁷Sr/⁸⁶Sr, ¹⁴³Nd/¹⁴⁴Nd and whole-rock Pb indicate that the magmas may be derived from a remnant of subducted oceanic lithosphere which has been variously depleted by the prior generation of basaltic melts. Isotopic enrichment above the level seen in MORB's is due in part to crustal contamination. The isotopic results are very different than those obtained from samples erupted through thin, allochthonous crust in the Intermontane Belt and may be explained in part by generation of the magmas in oceanic material which was subducted when allochthonous crust lay against the parautochthonous rocks underlying the Wells Cray—Clearwater area. The alkali olivine basalts of the Wells Cray—Clearwater area have erupted onto a tectonically active surface. A peneplain (erosion surface), formed in Eocene-Miocene time has been uplifted since the Miocene and uplift may be continuing. This uplift is in response to an elevated geothermal gradient which may be due to crustal extension. This crustal extension may be similar to that which occurred in the Eocene. The elevated geothermal gradient and reduced pressures attendant with recent uplift and erosion may have initiated basaltic volcanism in the region, rather than a fixed mantle hot spot as proposed in earlier work.
Science, Faculty of
Earth, Ocean and Atmospheric Sciences, Department of
Graduate

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28

Aliotta, Marco Antonio. "Data mining techniques on volcano monitoring." Doctoral thesis, Università di Catania, 2013. http://hdl.handle.net/10761/1364.

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The aim of this thesis is the study of data mining process able to discover implicit information from huge amount of data. In particular, indexing of datasets is studied to speed the efficiency of search algorithm. All of the presented techniques are applied in geophysical research field where the huge amount of data hide implicit information related to volcanic processes and their evolution over time. Data mining techniques, reported in details in the next chapters, are implemented with the aim of recurrent patterns analysis from heterogeneous data. This thesis is organized as follows. Chapter 1 introduces the problem of searching in a metric space, showing the key applications (from text retrieval to computational biology and so on) and the basic concepts (e.g. metric distance function). The current solutions, together with a model for standardization, are presented in Chapter 2. A novel indexing structure, the K-Pole Tree, that uses a dynamic number of pivots to partition a metric space, is presented in Chapter 3, after a taxonomy of the state-of-the-art indexing algorithm. Experimental effectiveness of K-Pole Tree is compared to other efficient algorithms in Chapter 4, where proximity queries results are showed. In Chapter 5 a basic review of pattern recognition techniques is reported. In particular, DBSCAN Algorithm and SVM (Support Vector Machines) are discussed. Finally, Chapter 6 shows some geophysical applications where data mining techniques are applied for volcano data analysis and surveillance purpose. In particular, an application for clustering infrasound signals and another to index an thermal image database are presented.

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29

Wright, Daniel Frederick. "Evaluating volcanic-hosted massive sulphide favourability using GIS-based spatial data integration models, Snow Lake area, Manitoba." Thesis, University of Ottawa (Canada), 1996. http://hdl.handle.net/10393/10064.

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Maps showing spatial variation of volcanic-hosted massive sulphide (VHMS) potential in the Snow Lake area have been generated by combining digital data from a variety of sources. An exploration model, based on a VHMS deposit model, but expanded to include regional exploration datasets, provides a conceptual framework for the extraction of predictive evidence from the raw data sources. The evidence is divided into five factors: stratigraphic evidence, evidence related to available heat, alteration evidence, geophysical evidence and geochemical evidence. Stratigraphic evidence is derived from the presence of favourable volcanic lithologies, and the proximity to contacts between volcanic flows and volcanic breccia. Heat evidence is derived from proximity to subvolcanic tonalite sills (the inferred primary heat source) and proximity to synvolcanic dykes. The alteration evidence is deduced from the presence and proximity to mapped alteration, mainly silicification, Fe-Mg metasomatism and pyritization. The geochemical evidence is a combination of a lake sediment signature (derived by principal components analysis), and individual maps of Pb, Zn and Cu in till. The geophysical factor is a combination of magnetic, gravity and VLF components. Four approaches have been applied for combining spatial evidence to predict mineral potential. (1) The weights of evidence method (data-driven) is used to characterize the spatial associations between the known deposits, and to calculate weights for each predictive map layer. The output is a favourability map expressed as the posterior probability of a VHMS deposit occurring per unit area. The magnitude of the weights allow the evidence to be ranked according to predictive capability. (2) A second data-driven method, area weighted logistic regression, was applied using the same binary evidence maps as used in the weights of evidence method. The binary maps, representing the independent variable in the model, were combined to form irregularly shaped polygons with unique combinations of evidence. The observations for each polygon were weighted according to the area of the unique-polygon. The dependent variable was the presence of a deposit. This model was not constrained by the assumption of conditional independence. (3) In the fuzzy logic method, evidence is expressed in terms of fuzzy membership functions, subjectively assigned by an expert, for each predictor map. An inference network is constructed to mimic the decisions made by an exploration geologist, using a variety of fuzzy combination rules that reflect varying degrees of logical AND and OR. (4) Dempster-Shafer belief theory is more flexible than fuzzy logic for representing uncertainty in the data, but is somewhat restricted in the expressiveness of the combination rules. The Dempster-Shafer output consists of favourability maps for "support" (conservative), "plausibility" (optimistic), and "ignorance" (uncertainty). Comparing the results from the four different methods shows that they all have a similar spatial distribution of areas of high favourability. The known deposits are in highly favourable zones, as expected, and a number of prospective areas have the right combination of factors, but no known deposits. The new VHMS discovery at Photo Lake made during summer 1994 is in a favourable zone as predicted by these models.

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30

Gerlach, David Christian. "Geochemistry and petrology of recent volcanics of the Puyehue-Cordon Caulle Area, Chile (40.5S̊)." Thesis, Massachusetts Institute of Technology, 1985. http://hdl.handle.net/1721.1/60119.

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Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Earth, Atmospheric, and Planetary Sciences, 1985.
Microfiche copy available in Archives and Science.
Folded map in pocket at back of thesis.
Bibliography: leaves 369-388.
by David Christian Gerlach.
Ph.D.

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31

Heikura, A. (Antti). "The volcanic rocks of the Länkipohja-Jämsä area in the southern part of the Central Finland Granitoid Complex." Master's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201704251579.

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The Länkipohja-Jämsä area is situated in the southern part of the Central Finland Granitoid Complex and consists of granitic plutonic rocks and supracrustal rocks including intermediate volcanic rocks and volcanogenic sediments accompanied with less abundant mafic and felsic variants. It is a part of the eastern extension of the well-studied Tampere schist belt located between the Central Finland Granitoid Complex to the north and Pirkanmaa migmatite belt to the south. To the east of the study area is the Makkola area, also geologically related to the Tampere schist belt. The deformational events in these supracrustal areas are related to the collision of Central and Southern Svecofennia at 1.88–1.87 Ga. The purpose of this Master’s project was to study the volcanic and volcanogenic rocks of the study area extending over an area of 30 x 20 km and assess their tectonic setting and genesis. The study is part of the Gold Potential Mapping Project of the Geological Survey of Finland (GTK). The data include more than 1300 field observations, 80 thin sections and 85 geochemical analyses. Some older field observations and geological and aeromagnetic maps were also utilized. The occurrences of volcanic rocks have been divided into five subareas: Partala, Kakaristo, Mustajärvi, Ouninpohja, and Länkipohja. The volcanic rocks have mainly intermediate, calc-alkaline to shoshonitic composition, they are enriched in light rare earth elements, depleted in high-field strength elements, and have trace element features that plot them in arc volcanic and active continental margin settings in tectonic discrimination diagrams. The volcanic rocks of Länkipohja and Partala areas are more acidic and alkaline than other volcanic rocks of this study. Otherwise, no remarkable differences in geology or geochemistry were found between the subareas of the study area and the Makkola area to the east and the Tampere schist belt to the west. It is concluded that the whole geological system has formed in a continental arc setting. Furthermore, the presence of a subduction component is inferred from large LILE/HFSE ratio. Despite some signs of hydrothermal alteration, the ore potential of the area is low, disregarding orogenic gold and quartz vein related gold deposits.

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32

Ingalls, Andrew. "Reconnaissance Cenozoic volcanic geology of the Little Goose Creek area, northeastern Elko County, NV with an emphasis on the Jarbidge Rhyolite." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18195.

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Master of Science
Department of Geology
Matthew Brueseke
The Little Goose Creek area is located in Elko County, Nevada just south of the central Snake River Plain and in the northeastern Great Basin. During the Miocene, northeastern Nevada was characterized by volcanism as well as prevalent extension and basin development, including widespread occurrences of porphyritic quartz-phyric silicic lavas and domes (e.g., the Jarbidge Rhyolite), ash-flow tuffs, and basaltic volcanism. Recent workers (e.g., Colgan and Henry, 2010) have provided new constraints on the timing of extension in the northern Great Basin (U.S.A.) and indicate that much of it occurred in the mid-Miocene. Other recent work has provided new temporal and petrologic constraints on 16.1 to 15.0 Ma Jarbidge Rhyolite volcanism in the northern Great Basin west of our study area, and suggest that it is intimately linked (spatially and temporally) with the aforementioned extension. This study aims to: [1] understand the spatiotemporal link between the volcanism in the northeastern Nevada study area and potentially correlative volcanism regionally (e.g., Jarbidge Rhyolite and explosive deposits associated with the <13 Ma Bruneau-Jarbidge or Twin Falls eruptive centers); [2] determine if the sampled Jarbidge Rhyolite lavas are chemically similar to those in and around Jarbidge, Nevada. In the Goose Creek area, we report a new laser [superscript]40Ar/[superscript]39Ar age for sanidine of 13.6 ± 0.03 Ma for a crystal-poor rhyolite lava (Rock Springs Rhyolite) and a Jarbidge Rhyolite lava (13.827±0.021 Ma) as well as an age on Jarbidge Rhyolite in Wells, NV (15.249±0.040 Ma) and West Wendover, NV (13.686±0.034 Ma). These lava samples, as well as sampled ash-flow tuffs from the Goose Creek region, plot within the A-type field on discrimination diagrams. The ash-flow tuffs are younger than the Rock Springs Rhyolite based on stratigraphic relationships and are sourced from both the Twin Falls eruptive center as well as the Bruneau Jarbidge eruptive center of the central Snake River Plain based on geochemical analysis. Also, a sequence of basaltic lavas crop out in the Goose Creek drainage; these basalts have ~43 wt.% silica and are chemically similar to <8 Ma olivine tholeiite basalts that crop out to the north, along the southwestern side of the Cassia Mountains, Idaho. These results, field relationships, and prior geological mapping suggest that the lavas and ash-flow tuffs erupted into active extensional basins.

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33

O'Brien, Jeremy Mark. "Hydrogeochemical Characteristics of the Ngatamariki Geothermal Field and a Comparison with the Orakei Korako Thermal Area, Taupo Volcanic Zone, New Zealand." Thesis, University of Canterbury. Geological Sciences, 2010. http://hdl.handle.net/10092/4097.

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The Ngatamariki Geothermal Field is located 20 km north of Taupo in the Taupo Volcanic Zone and has a boundary of 12 km² as delineated by magneto-telluric surveys (Urzua 2008). Rhyolitic deposits, derived from the Maroa Volcanic Centre, dominate the geology of the area with the 186 AD (Wilson et al. 2009) Taupo pumice mantling stream valleys in the area. The majority of thermal features at Ngatamariki are located along the Orakonui Stream on the western boundary of the field; the stream area is dominated by a 50x30 m geothermal pool filling a hydrothermal eruption crater. This crater was formed during a hydrothermal eruption in 1948, with a subsequent eruption in April 2005. Orakei Korako is located 7 km north of Ngatamariki and has one of the largest collections of thermal features in New Zealand. The geology at Orakei Korako is similar to Ngatamariki, but the area is dominated by a series of south-west trending normal faults which create sinter terraces on the eastern bank of Lake Ohakuri. Water samples from springs and wells at Ngatamariki and Orakei Korako were taken to assess the nature of both fields. Spring waters at Ngatamariki have chloride contents of 56 to 647 mg/l with deep waters from wells ranging from 1183 to 1574 mg/l. This variation is caused by mixing of deep waters with a steam heated groundwater, above clay caps within the reservoir. Stable isotopic results (δ¹⁸O and δD) suggest that reservoir waters are meteoric waters mixed with magmatic (andesitic) water at Ngatamariki. Reservoir water chemistry at Orakei Korako exhibits low chloride contents, which is anomalous in the Taupo Volcanic Zone. Chloride content in well and spring waters is similar ranging from 546 to 147 mg/l, due to mixing of reservoir fluids with a ‘hot water’ diluent at depth. Isotopic compositions of spring waters suggest that they are meteoric waters which mix with magmatic (rhyolitic) water, more enriched in δ¹⁸O and δD than ‘andesitic’ water. Relationships between major ion concentrations and known subsurface geology suggest there is no hydraulic connection between the two fields.

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34

Moe, Aung. "Structural development of a volcanic sequence of the Lahn area during the variscan orogeny in the Rhenohercynian belt (Germany)." [S.l. : s.n.], 2000. http://deposit.ddb.de/cgi-bin/dokserv?idn=961466162.

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35

Lees, Katherine Roisin. "Magmatic and tectonic changes through time in the Neogene volcanic rocks of the Vale area, Oregon, north western USA." Thesis, Open University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261042.

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36

Mercer, Lonnie T. "Geology of the Tierras Blancas Area in the Southeastern Acambay Graben, Central Mexico." BYU ScholarsArchive, 2005. https://scholarsarchive.byu.edu/etd/303.

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Pliocene-Pleistocene sediments in the southeastern Acambay graben, central Mexico have yielded mammal fossils, including Equus simplicidens, cf. Rhynchotherium, ?Camelops, Mammuthus sp., Bison sp., and Antilocapra sp. The fossiliferous sediments include a period of lacustrine sedimentation in the late Pliocene-early Pleistocene that interrupted fluvial and alluvial sedimentation during the early Pliocene and Pleistocene. The sediments deposited in this late Pliocene paleolake record a history of lake level fluctuations, shown by lithologic variations in lacustrine sediments and abundance of vertebrate burrows. Volcanic and tectonic events in the Acambay graben were the major controls on sedimentation during Pliocene-Pleistocene time. Various local volcanic structures produced source rocks for Pliocene-Pleistocene sediments, and intra-arc extensional tectonics caused basin subsidence. Blockage of stream drainages by lava flows or perhaps increased basin subsidence contributed to the appearance of and fluctuations in the lacustrine system during the late Pliocene. Diatom assemblages from lacustrine sediments indicate slightly higher precipitation and humidity than present-day conditions in the Acambay graben. Therefore, climatic forcing may have also contributed to the development of the late Pliocene paleolake in the Acambay graben. Pliocene-Pleistocene volcanic rocks in this part of the Acambay graben range from basaltic andesite to rhyolite. The calc-alkaline composition of these volcanic rocks is similar to others in the modern Mexican Volcanic Belt; they have a continental arc affinity, which is consistent with a tectonic setting within the Mexican Volcanic Belt. The major eruptive episode in the Acambay graben occurred during the early Pliocene, although volcanism, represented by small volcanic structures, continued until the late Pleistocene. This observed decline in volcanism in the Acambay graben correlates with a early Pliocene through Quaternary trenchward migration of volcanism in the Mexican Volcanic Belt.

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37

Yurtmen, Sema. "Petrological and geochemical studies of Pre-Cretaceous metamorphic and Pliocene volcanic rocks in the area of northeast of Nigde, Turkey." Thesis, Keele University, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.296022.

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38

Hanna, Teresa Rae. "Areal Extent and Volumes of the Dinner Creek Tuff Units, Eastern Oregon Based on Lithology, Bulk Rock Composition and Feldspar Mineralogy." PDXScholar, 2018. https://pdxscholar.library.pdx.edu/open_access_etds/4346.

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The Dinner Creek Tuff erupted during a period of rhyolitic volcanism coeval to the flood volcanism associated with the Columbia River Basalt Group. The High Rock Caldera Complex, Lake Owyhee and McDermitt volcanic fields account for ~90% of the rhyolites erupted between 16.7-15.0 Ma. Situated at the northern end of the Lake Owyhee volcanic field, the Dinner Creek Tuff was originally mapped as a ~2,000 km2 single ignimbrite confined to the Malheur Gorge. Streck et al. (2015) correlated tuff outcrops previously mapped as generic Miocene welded tuff as well as local units such as the "Mascall" or "Pleasant Valley" tuff of eastern Oregon to individual cooling units that comprise the newly redefined Dinner Creek Tuff, enclosing an area of ~25,000 km2. Areal extents defined in this study show that all outcrops now determined to be Dinner Creek Tuff enclose an area of ~31,800 km2 not including any fallout deposits that likely extended beyond the defined area. Although Dinner Creek Tuff rhyolites have nearly identical compositions, different ages and subtle geochemical and mineralogical differences exist and were used to divide the Dinner Creek Tuff into four discrete cooling units. Except for unit 4, the units are lithologically very similar. Unit 1 is the Dinner Creek Tuff unit associated with the Malheur Gorge type section. The four cooling units have ages of 16.15-16 Ma (unit 1), 15.6-15.5 Ma (unit 2), 15.46 Ma (unit 3) and 15.0 Ma (unit 4). Areal extents were established for all four cooling units based on feldspar compositions along with lithological and bulk rock geochemical data. Minimal extents of individual units are as follows: ~22,590 km2 (unit 1), ~17,920 km2 (unit 2), ~14,170 km2 (unit 3) and ~8,370 km2 (unit 4). Using conservative thicknesses, determined erupted tuff volumes are ~170 km3 (unit 1), ~125 km3 (unit 2), ~99 km3 (unit 3) and ~46 km3 (unit 4), totaling ~440 km3 and dense rock equivalents are ~152 km3 (unit 1), ~96 km3 (unit 2), ~76 km3 (unit 3) and ~31 km3 (unit 4), totaling ~356 km3. These extents and volumes are the absolute minimum based solely on the locations of exposed tuff sections and the inclusion of the source. Centering eruptive units on source areas where they are known, expands the tuff extents into a more radial pattern as would be expected for low-aspect ratio, high energy ash-flow tuff eruptions. These probable extents increase the areal extents of the individual units to: ~36,900 km2 (unit 1), ~31,660 km2 (unit 2), ~17,290 km2 (unit 3) and ~10,150 km2 (unit 4) distributed over a ~43,490 km2 area. Likewise, erupted tuff volume and dense rock equivalents also increase: volume-- ~277 km3 (unit 1), ~222 km3 (unit 2), ~121 km3 (unit 3) and ~56 km3 (unit 4); DRE-- ~248 km3 (unit 1), ~170 km3 (unit 2), ~93 km3 (unit 3) and ~38 km3 (unit 4). New mapping confirms previous hypotheses that the Castle Rock caldera erupted unit 1 and identified the new Ironside Mountain caldera as the source for unit 2 while precise source areas for unit 3 and 4 are not yet known but are thought to lie within the Dinner Creek Eruptive Center. Minimal calculated caldera volumes for units 1 and 2 are ~98.5 km3 (unit 1) and ~31.1 km3 (unit 2). Adding the thick ponded intra caldera tuff volume to the determined and probable erupted tuff volumes determined in this study, increases the erupted volumes to ~268 km3 (determined) and ~375 km3 (probable) for unit 1 along with ~157 km3 (determined) and ~253 km3 (probable) for unit 2. DREs increase to ~251 km3 (determined) and ~347 km3 (probable) for unit 1 along with ~128 km3 (determined) and ~202 km3 (probable) for unit 2.

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39

Ruch, Joël. "Volcano deformation analysis in the Lazufre area (central Andes) using geodetic and geological observations." Phd thesis, Universität Potsdam, 2010. http://opus.kobv.de/ubp/volltexte/2010/4736/.

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Large-scale volcanic deformation recently detected by radar interferometry (InSAR) provides new information and thus new scientific challenges for understanding volcano-tectonic activity and magmatic systems. The destabilization of such a system at depth noticeably affects the surrounding environment through magma injection, ground displacement and volcanic eruptions. To determine the spatiotemporal evolution of the Lazufre volcanic area located in the central Andes, we combined short-term ground displacement acquired by InSAR with long-term geological observations. Ground displacement was first detected using InSAR in 1997. By 2008, this displacement affected 1800 km2 of the surface, an area comparable in size to the deformation observed at caldera systems. The original displacement was followed in 2000 by a second, small-scale, neighbouring deformation located on the Lastarria volcano. We performed a detailed analysis of the volcanic structures at Lazufre and found relationships with the volcano deformations observed with InSAR. We infer that these observations are both likely to be the surface expression of a long-lived magmatic system evolving at depth. It is not yet clear whether Lazufre may trigger larger unrest or volcanic eruptions; however, the second deformation detected at Lastarria and the clear increase of the large-scale deformation rate make this an area of particular interest for closer continuous monitoring.
Vulkanische Deformationen in großem Maßstab, die mittels InSAR gemessen wurden, liefern neue Informationen und dadurch einen neuen Blickwinkel auf vulkan-tektonische Aktivitäten und das Verständnis von langlebigen, magmatischen Systemen. Die Destabilisierung eines solchen Systems in der Tiefe beeinflusst dauerhaft die Oberfläche durch Versatz des Bodens, magmatische Einflüsse und vulkanische Unruhen. Mit der Kombination aus kleinräumigem Bodenversatz gemessen mittels InSAR, numerischer Modellierung und langfristigen geologischen Beobachtungen, analysieren wir die Gegend um den Vulkan Lazufre in den Zentralanden, um die raumzeitliche Entwicklung der Region zu bestimmen. Bodenversatz wurde hierbei im Jahr 1997 mittels Radar-Interferrometrie (InSAR) gemessen, was eine Fläche von 1800 km² ausmacht, vergleichbar mit der Größe der Deformation des Kraters. Im Jahr 2000 wurde zusätzlich eine kleinräumige Deformation am Nachbarvulkan Lastarria entdeckt. Wir sehen räumliche als auch zeitliche Verbindungen zwischen der Deformation des Vulkans und vulkanischen Strukturen innerhalb der betroffenen Gegend. Wir folgern daraus, dass diese Beobachtungen der Ausdruck eines langlebigen, magmatischen Systems in der Tiefe an der Oberfläche sind. Es ist noch nicht klar, ob Lazufre größere vulkanische Unruhen, wie zum Beispiel Eruptionen auslösen könnte, aber die Deformation am Vulkan Lastarria und ein Anstieg der großräumigen Deformationsrate, machen diese Region interessant für eine zukünftige, kontinuierliche Überwachung.

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40

Gisbert, Pinto Guillem. "The Miocene volcanism of the Sulcis area (SW Sardinia, Italy): Petrology, petrogenesis and geodynamic significance." Doctoral thesis, Universitat de Barcelona, 2012. http://hdl.handle.net/10803/84110.

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During the Cenozoic the western Mediterranean area underwent a complex geodynamic evolution driven by the interaction between the African and Eurasian plates. The Corsica- Sardinia microplate played a central role in this evolution, which was recorded by its tectonic evolution and volcanism. During Oligo-Miocene the roll-back of the NW-wards subducting ,Apulian subduction zone caused the Corsica-Sardinia microplate to detach, drift and rotate from the European continental margin to its present position, opening the Liguro-Provençal Basin and generating abundant subduction-related calc-alkaline orogenic volcanism. After a 6 Ma-long pause in retreat, subsequent evolution of the roll-back since Pliocene left Sardinia in its current position as the trench retreated SE-ward opening the southern Tyrrhenian basin. Extensional tectonics related to this opening produced in Sardinia the generation of abundant anorogenic alkaline volcanism. In the Sulcis area, in SW Sardinia, a special volcanic suite was produced which began sharing the same calc-alkaline characteristics as the rest of the subduction-related volcanism throughout Sardinia, forming an andesitic lava domes and flows piling, but that later migrated to different compositions, mildly alkaline, including the rarely occurring peralkaline volcanism, which formed a mainly rhyolitic ignimbritic succession. In spite of the marked differences of the Sulcis magmatism, this special volcanic suite was considered to be only one more manifestation of the widespread subduction-generated orogenic volcanism of Sardinia. The present work has, at least partially, solved this situation. A thorough and detailed study of the Sulcis Oligo-Miocene volcanic suite has been carried out in this study involving the revision of the available data on volcanostratigraphy and cartography and the characterization of the geochemistry, petrography and mineral chemistry of the several units present in this suite, which has allowed us to obtain significant information on the petrogenesis of this suite and its geodynamic significance. As a result of the field and laboratory work all units have been characterised from the volcanostratigraphic, petrographic and geochemical point of view. A methodology for unit recognition based on whole rock geochemistry has been developed, which has been a fundamental tool for solving volcanostratigraphic and mapping doubts during the development of this work, and remains a powerful tool for future studies. The study of the whole rock geochemistry data has allowed us to obtain significant information on the generation of the magmas that formed the Sulcis volcanic suite and its geodynamic significance, and combination with petrographic observations has provided valuable information on the evolution of these magmas from its formation to its eruption. Isotope and trace element data have revealed the structure of the mantle beneath Sardinia, which is diffusely stratified with an upper part with an EMI signature and a lower more EARlike region, both of them having an OIB mantle source-like composition. Subduction during Oligo-Miocene released into the mantle wedge hydrous fluids and partial melts carrying sediment and MORB isotope and trace element compositions, which metasomatised this mantle, introducing mostly into the more EAR-like mantle a subduction signature. The Oligo-Miocene orogenic magmas in Sardinia, including the andesitic lower sequence in the Sulcis, were produced in the subduction-modified more EAR-like mantle portion by lowering of the melting temperature due to the input of subduction fluids. Magmas from the ignimbritic sequence in the Sulcis, though, are considered to represent a transition from orogenic to anorogenic magmatism. It is suggested that the transition was due to a change in the melting mechanism from fluid- to extension-controlled, related to the cessation in the subduction influence below the Sulcis. The mechanism proposed to explain the contemporaneous occurrence of both orogenic and anorogenic magmatisms in Sardinia during the emplacement of the Sulcis ignimbritic suite is the formation of a slab break-off which started south of Sardinia and progressed northward opening a slab window. The ignimbritic sequence in the Sulcis was formed by the arrival and differentiation of several magma batches with slightly different initial compositions, apparently at least one for each unit except for Lenzu and Seruci units, which formed by evolution of the magma that generated the immediately preceding units. Magma differentiation was dominated by crystal fractionation processes, which produced similar evolutionary trends, assimilation having a very small effect only appreciable in Pb isotopes.
Durant l’Oligo-Miocè el funcionament en roll-back de la subducció sota el marge continental europeu de l’oest Mediterrani va provocar el desenganxament de la microplaca Sard-Corsa d’aquest marge i la seva migració primer amb una translació cap al SE i posteriorment amb una rotació en sentit antihorari fins a assolir la seva posició actual. Associada a aquest desplaçament es va produir l’obertura de la conca Liguro-Provençal en posició de back-arc. Com a resultat de la subducció es va produir abundant magmatisme calco-alcalí d’afinitat orogènica a l’illa de Sardenya. A la zona del Sulcis, al SW de Sardenya, el magmatisme va compartir inicialment les mateixes característiques que la resta del magmatisme sard, formant un apilament de doms i colades làviques de composicions andesítiques. Però cap als estadis finals del cicle magmàtic, els magmes generats van migrar de composició, donant lloc a un apilament d’unitats ignimbrítiques amb composicions majoritàriament riolítiques de transicionals a lleugerament alcalines. Malgrat la marcada diferència composicional entre la seqüència ignimbrítica del Sulcis i la resta del magmatisme Oligo-Miocè sard, aquesta va ser considerada com un exemple més d’aquest magmatisme. Per resoldre en part aquesta situació s’ha realitzat aquesta tesi. En aquest estudi s’ha revisat la seqüència vulcanoestratigràfica descrita així com les cartografies existents per tal de realitzar un mostreig sistemàtic de la seqüència ignimbrítica. L’estudi de les mostres recollides ha permès caracteritzar totes les unitats que formen la seqüència des del punt de vista de petrogràfic i geoquímic. Les dades obtingudes han permès desenvolupar una metodologia per al reconeixement de les unitats ignimbrítiques en base a la geoquímica de roca total, així com abordar l’estudi de la petrogènesi d’aquesta associació magmàtica. S’ha obtingut informació sobre l’àrea font dels magmes, que ha pogut ser caracteritzada, sobre els mecanismes de formació dels magmes estudiats i el seu significat geodinàmic, i sobre els processos que van controlar l’evolució dels magmes des de la seva formació fins a la seva expulsió en superfície en forma de materials volcànics.

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41

Di, Stefan Agnese Giuseppa Federica. "Next generation of numerical models for inferring the volcano dynamics from geophysical observations." Doctoral thesis, Università di Catania, 2012. http://hdl.handle.net/10761/1074.

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We present a 3D numerical model based on FEM (Finite Element Method) to jointly evaluate geophysical changes caused by dislocation and overpressure sources in volcanic areas. A coupled numerical problem was solved to estimate ground deformation, gravity and magnetic changes produced by stress redistribution accompanying magma migration within the volcano edifice. We successfully applied the integrated numerical procedure to image the inflation process of 2005-2006 and the magmatic intrusion of the 2008 eruption. A hybrid approach for forward and inverse geophysical modeling, based on Artificial Neural Networks (ANN) and Finite Element Method (FEM), is proposed in order to properly identify the parameters of volcanic pressure sources from geophysical observations at ground surface. Our FEM-based approach improves the reliability of model-based assessments of geophysical observations that can prelude to an impending eruption.

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42

Holroyd, Jonathan David. "The structure and stratigraphy of the Suardal area, Isle of Skye, northwest Scotland : an investigation of tertiary deformation in the Skye volcanic complex." Thesis, University of Manchester, 1994. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.659361.

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43

Yoshikawa, Miyuki. "Seismic velocity structure beneath Otake-Hatchobaru geothermal area at Kuju Volcano in the central Kyusyu, Japan." 京都大学 (Kyoto University), 2004. http://hdl.handle.net/2433/147827.

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44

Oswin, W. M. "Upper Devonian/lower carboniferous volcanism and mineralisation in the area east of the Rio Tinto mines, Iberian Pyrite Belt." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375672.

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45

Jones, Julie Amanda. "Geology of the Camboon volcanics in the Cracow area, Queensland : implications for the permo-carboniferous tectonic evolution of the New England fold belt /." [St. Lucia, Qld.], 2006. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19453.pdf.

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46

Kiuchi, Ryota. "New Ground Motion Prediction Equations for Saudi Arabia and their Application to Probabilistic Seismic Hazard Analysis." Kyoto University, 2020. http://hdl.handle.net/2433/253095.

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47

Giuffrida, Marisa. "Magma storage, ascent and degassing histories traced by textures and chemical zoning in crystals: application to the C02-Rich basaltic system of Mt. Etna Volcano." Doctoral thesis, Università di Catania, 2018. http://hdl.handle.net/10761/3632.

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An extensive compositional dataset of plagioclase and olivine crystals from lavas emitted between the 2011 and 2013 at Mt. Etna has been used to constrain modes and timescales of magma storage and transfer to the surface. Plagioclase crystals display either near-equilibrium or disequilibrium textures at the core and rim that indicate complex histories of magma crystallization under variable chemical and physical conditions. Crystals with different textures have been characterized for major (An), minor (Fe and Mg) and trace elements (Sr/Ba). The Sr /Ba ratio in oscillatory-zoned plagioclase revealed the presence into the plumbing system of low-Sr magma volumes that preserve a geochemical signature similar to that of magmas feeding the historic, pre-1971 activity. Fe and Mg zoning vs anorthite in correspondence of plagioclase sieve textures also suggest that processes of gas-flushing have had a dominant role in triggering the paroxysmal eruption, determining a sudden intensification of the eruption intensity up to the fountaining phase. In order to interpret the range of crystal textures and compositions that may form in CO2-rich systems, a series of experiments was conducted to reproduce processes of CO2-flushing at distinct sections of the plumbing system. Starting from an initial material containing a pure-H2O fluid, experiments were performed at temperature of 1080°C and at two distinct pressures of 100 MPa and 300 MPa, using volatile mixtures at variable H2O+CO2 concentrations. Results show that CO2-flushing at high pressure greatly promote plagioclase destabilization during their early grow history, and is therefore one of the main mechanism responsible for the spectrum of disequilibrium textures at the plagioclase cores. The transfer and injection of prevalent CO2-rich gases at shallow (~100MPa) depth mostly reduce the clinopyroxene stability, causing severe destabilization of their rims. Through Sr-diffusion modelling in plagioclase the maximum time of magma storage during the considered eruptive period has been evaluated. Timescales of crystal residence in the plumbing system are short (five years to three decades), suggesting limited magma storage and faster transfer dynamics to the surface. The investigation of Li diffusion in plagioclase allow a direct quantification of magma ascent and vesiculation upon eruption. Li diffusion calculations yield timescales of sin-eruptive magma ascent between 20 and 30 sec, corresponding to rates of 50-75 m/s. Chemical zoning of olivine crystals highlights processes of multi-step magma transfer and residence at different levels of the plumbing system. The migration of magmas to the surface occurred primarily stepwise through multiple episode of injection and mixing between five compositionally-distinct magmatic environments (Mi), whose P-T- O2 characteristics and concentrations in dissolved volatiles were constrain by thermodynamic modeling. From a deepest reservoir, located at depth of ~600 MPa, the most primitive magma M1 (Fo84) moved along dominant pathways, intercepting the M2 (Fo80-82) at ~390 MPa and/or M3 (Fo78; 250 MPa), M4 (Fo75; ~140 MPa) and finally the shallow M5 (Fo70-73; ~40 MPa) storage zone. For some eruptive episodes, olivine zonings highlight a preferential route of transfer, connecting the M1 and M5 storage zones that facilitated the migration of primitive magma at shallow depth. Fe-Mg diffusion modelling on olivine normal and reverse zoning defines the timescales of magma transfer and storage across these magmatic environments, which vary from ~1 to 18 months, whereas intrusion and mixing by more basic magma into the shallowest reservoir occurred always within 5 months before eruption. Relevance of this study mainly relies on the quantification of volcanic processes at depth that may have considerable consequences in development of unusual, high-energy eruptions at basaltic volcanoes, generally acknowledged for their weak to mild explosive activity.

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Gallagher, Brookie. "A comparative study of the Badger Pass igneous intrusion and the foreland volcanic rocks of the McDowell Springs area, Beaverhead county, Montana implications for the local late cretaceous sequence of events /." unrestricted, 2008. http://etd.gsu.edu/theses/available/etd-04212008-172506/.

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Thesis (M.S.)--Georgia State University, 2008.
Title from file title page. Timothy E. LaTour, committee chair; Hassan A. Babaie, Eirik J. Krogstad, William J. Fritz, committee members. Electronic text (111 p. : ill. (some col.), maps (some col.)) : digital, PDF file. Description based on contents viewed Aug. 20, 2008. Includes bibliographical references (p. 100-104).

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Gallagher, Brookie Jean. "A Comparative Study of the Badger Pass Igneous Intrusion and the Foreland Volcanic Rocks of the McDowell Springs Area, Beaverhead County, Montana: Implications for the Local Late Cretaceous Sequence of Events." Digital Archive @ GSU, 2008. http://digitalarchive.gsu.edu/geosciences_theses/11.

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Abstract:

Intermediate igneous rocks exposed in the Badger Pass area and 3.5 km away in the McDowell Springs area of Beaverhead County, Montana, previously mapped as Cretaceous intrusive (Ki), and Cretaceous undifferentiated volcanics (Kvu) respectively, exhibit little geochemical variation. Trace element, and lead isotope analyses provide strong evidence allowing for a single source. REE patterns, obtained through ID-ICP-MS, are essentially identical. Mineral/melt Eu analyses reveal that Eu behaved predominantly as a divalent cation, refuting an earlier study asserting that trivalent Eu dominated. Data suggest rocks were formed under low oxygen activity conditions, not oxidizing conditions as previously reported. Geochemical data combined with field mapping allow us to establish the temporal relationship between late Cretaceous thrusting, intrusion, and volcanism in this locale. Folding, faulting and thrusting were significantly, if not entirely, completed prior to the commencement of volcanism. Volcanism included contemporaneous thrust plate intrusion, foreland extrusion, and hypabyssal foreland intrusion.

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Grassi, Sabrina. "Characterization of active tectonic structures of the Etna volcano, through geophysical surveys, analysis of site response and deformation." Doctoral thesis, Università di Catania, 2017. http://hdl.handle.net/10761/3902.

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In this thesis are shown the results of a multidisciplinary research, including geophysical, structural and geodetic surveys, carried out along the Tremestieri-Trecastagni-San Gregorio-Acitrezza fault system with the aim to provide additional insightful about its geometry and kinematics; also, additional geophysical surveys were performed at various sites of the municipalities most affected by the fault segments presence in order to obtain information on site response. This fault system, considered as "laboratory structure", was selected for the different kinematic characteristics and different modes of strain-energy release, that characterized its fault segments. In the northernmost portion, this system has a kinematic behavior of normal fault and releases energy during coseismic deformation, while in the southernmost portion presents a kinematic behavior of a right-lateral strike-slip fault with releases energy during aseismic creep. Furthermore, this fault system, which can be considered the southern boundary of the sliding of Etnean eastern slope, was less studied than the northern sliding boundary and very little is known about the depth geometry of its fault segments. The surveys were performed after an analysis of the data relating to shallow geology and to morphological, structural, stratigraphic, geophysical and seismological aspects; these detailed surveys have confirmed and highlighted a variety of geological and geomorphological conditions that can determine the existence of different stress following the occurrence of an earthquake. After have performed a detailed structural survey, the project has planned the acquisition and analysis of many ambient noise samplings, and of other geophysical surveys, undertaken within the municipalities affected by the presence of the fault segments, increasing the surveys near the fault. All this in order to reconstruct the resonance frequency distribution and detect the possible presence of areas affected by amplification effects. Moreover, in some areas, the surface deformation process was characterized through the design, implementation and installation, across the fault segments, of a geodetic monitoring network, in order to obtain information on the fault kinematics and on the local stress field. The integration of the results obtained from structural, geological and geophysical surveys, with a complete literature review has provided important information on the development in depth of the fault segments; it was thus possible to reconstruct a 3D model of geometry that characterized the southern boundary of Etnean eastern slope sliding. Various deformation data such as GPS displacements, InSAR images, level data and measures with extensometers suggest that the slip along the fault system is not uniform, but can be better described by a distribution of dislocation sources along the fault surfaces. In order to model the slip distribution along the fault surfaces, an inverse modeling of DInSAR deformation data was carried out. This project was aimed to the recognizing site effects, that characterize the studied areas, in order to highlight the seismo-stratigraphic and tectonic behavior of subsoil, as well as, to the characterization of the deformation field related to the fault segments, through the implementation of a new geodetic monitoring network (GEO-UNICT geodetic network). The results allowed to obtain important information on all parameters that can increment the local seismic hazard; all these different but converging approaches, have permitted a complete study of the investigated area. This study providing essential information for a proper land use planning, having as main objective the mitigation of risks that can affect the population.

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Dissertations / Theses on the topic 'Volcanic areas'

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