Dissertations / Theses on the topic 'Volcanic Plain'

The Snake River Plain (SRP) is one of the best-preserved examples of continental hotspot volcanis, with a continuous record of volcanism that extends over 16 Ma to the present. Yellowstone-Snake River Plain records the migration of plume-tail volcanism from inception at the Bruneau-Jarbridge caldera complex at 12.6 Ma to its present locus, under the Yellowstone Plateau. Records kept by the Snake River Plain volcanic actions include rhyolite lavas and ignimbritesm minor coeval basalts, and an overlying veneer of younger basalts. The central SRP has received comparatively little attention in the past. The Kimama core hole was drilled as part of Project Hotspot, the Snake River Scientific Drilling Project, which seeks to understand the long-term volcanic and sediment logical history of the SRP volcanic province. The Kimama core hole is the only part of the SRP that has not been scientifically drilled and cored to a significant depth in the past. Investigations of subsurface stratigraphy in continental volcanic provinces such as the SRP-YP are limited by the by the relatively low depth and spatial distribution of cored wells. The study of the Kimama core provides us with a continuous record of basalt and minor sediment deposition. The long-term volcanic history of the SRP, documented by moving magma and its composition, demonstrates that magmatism is mantle plume-derived. Our investigation of the Kimama core, combined with new mantle tomography, provides evidence that refutes non-plume models for the origin of the Snake River Plain volcanic province.

Native grasslands are one of the most endangered ecosystems in Australia. Approximately 99% of native grasslands have been disturbed for agriculture and pastoralism. Today, however, many agricultural and grazing lands have been abandoned. Restoring abandoned areas to native grassland is a challenge that must be met if these systems are to persist. This thesis sought to gain a better understanding of the biotic and abiotic barriers to restoring native grasslands in ex-cropping land, and to investigate novel techniques to overcome them in degraded native grassland in the Victorian Volcanic Plains. Firstly, I compared ex-cropland to high-quality remnant grassland, and showed that excropland supports a high number of exotic weeds, a lack of native species propagules, high nutrient levels (especially phosphorus and nitrogen), and an absence of organic carbon—all barriers which must be overcome if native grassland restoration is to succeed. I conducted a replicated field experiment in ex-cropland, to investigate four restoration approaches to overcoming barriers to restoration: (i) adding urban green waste to heat and kill the exotic seed bank (ii) adding sugar and/or mulch to promote microorganism and draw down soil nitrogen, (iii) using a modified clay product called Phoslock to reduce soil phosphorus levels, and (iv) scalping of topsoil 10 cm on ex-cropland site to remove the exotic seed bank and high nutrient soil. After each treatment, native grass seed was added, and the vegetation, seed bank, soil nutrients and microbial activity were monitored over 2.5 years. The hot mulch, scalping and sugar treatments all achieved significantly greater cover of native grasses than the control treatments. The hot waste treatment also effectively eliminated the exotic weed seed bank, but the soil N levels increased dramatically, which is counterproductive to the long-term goals of grassland restoration. Scalping out-performed all other treatments with regard to reducing soil N and P. All treatments suffered from reinvasion by exotic species, suggesting that any grassland restoration technique needs to be coupled with ongoing exotic weed management. Abstract ii High soil phosphorus is a difficult barrier to restoration of native grassland. A possible way to address this is to use plants with high P uptake to help draw down soil P. Native grassland taxa from the genus Ptilotus have been shown to have high P-uptake. I conducted two studies of Ptilotus macrocephalus and Ptilotus polystachyus to investigate their potential in this role. The first of these was an examination of techniques to break their seed dormancy, and to find their optimum germination conditions. I tested their response to smoke water, heating shock, cold stratification and gibberellic acid. The highest germination rates (62% and 38% for P. microcephalus and P. polystachyus, respectively) were achieved when the seeds were pre-treated with GA500 and exposed to a temperature range of (20/18OC) and a 12h dark/12h light regime. Smoke water, heat shock and the removal of floral bracts also improved germination rates, but not at the same magnitude as GA. The second study of Ptilotus was a glasshouse trial that examined the effectiveness of the two taxa at reducing available soil phosphorus. This trial included a third high P-uptake species (Lupinus albus) for comparison, and also investigated if the addition of Phoslock® could bind soil P into insoluble forms. P. macrocephalus and P. polystachyus accumulated high amounts of soil P. Thus, several years of seeding and harvesting of these plants is anticipated to provide a useful option for soil P reduction. Phoslock® reduced soil available P, but only at high concentration of Phoslock 1500 g/m2 and at very high soil P concentrations; it was less effective at levels that typically expect in ex-cropping paddocks. The findings of this thesis have advanced our current knowledge of the restoration of excropland. The research has tested methods to overcome biotic and abiotic barriers to restoration of the Victorian Volcanic Plains grasslands, and has demonstrated some practical approaches to begin the treatment. It was suggested that many of the methods and techniques used in this study could be useful technique in broad areas of grassland restoration within Australia as well as in similar situations in temperate climate conditions across the globe.
Doctor of Philosophy

Rhyolites of the Picabo volcanic field (10.4-6.6 Ma) of the Yellowstone hotspot in eastern Idaho are preserved as thick ignimbrites and lavas along the margins of the Snake River Plain. This study presents new O and Hf isotope data and U-Pb geochronology from individual zircons, O isotope data from major phenocrysts, whole rock Sr and Nd isotope data, whole rock geochemistry, and trace element and volatile analyses of quartz-hosted melt inclusions, which were used to characterize the evolution of rhyolite generation through the eruptive sequence. The chemical composition of the first eruption of the caldera complex, the Tuff of Arbon Valley, suggests magma generation through repeated magma injection into the crust, remelting, crystallization, mixing, and crustal assimilation. Subsequent eruptions have diverse and low δ18O signatures indicating rhyolite generation through the remelting of variably hydrothermally altered volcanics, followed by rapid batch assembly. This thesis includes co-authored material previously published.

This study presents a probabilistic lava flow hazard assessment for the Idaho National Laboratory (INL) and the cities of Idaho Falls and Pocatello, Idaho. The impetus of this work is to estimate the conditional probability that a lava flow on the eastern Snake River Plain (ESRP) will impact the areas of interest given the formation of a new volcanic vent in the region. A list of 288 eruptive events, derived from a previously published inventory of 506 surface and 32 buried vents, was created to reduce the biasing of spatial density maps towards eruptions with multiple dependent vents. Conditional probabilities of new vents and events occurring on the ESRP were modeled using the the Sum of Asymptotic Mean Squared Error (SAMSE) optimal pilot bandwidth estimator with a bivariate Gaussian kernel function. Monte Carlo analyses of potential eruption scenarios were performed using MOLASSES, a cellular automata fluid flow simulator. Results show that Idaho Falls is impacted <1% of the time for both the vent and event simulations; Pocatello is not impacted by any simulated flows. 25.45% of vent flows and 33.74% of event flows breach the boundaries of INL. 18.27%of vent and 25.85% of event simulations initiate on the INL property. Annual inundation probabilities of 1.06 x 10-4 for vent-based flows and 7.12 x 10-5 for event-based flows are reported for INL; annual probabilities of an eruptive center initiating on INL property are 7.60 x 10-5 for vents and 5.45 x 10-5 for events. All of these values exceed the International Atomic Energy Agency’s acceptable risk probability of 10-7 by several orders of magnitude.

Volcanoes are key indicators of a planet's internal structure, mechanics, and evolutionary history. Consequently, understanding the types and ages of volcanoes on a planet's surface is an important endeavor. In an attempt to better understand the relationship between morphometry and volcanic processes, we compared low-shield volcanoes on Syria Planum, Mars, with basaltic shields of the eastern Snake River Plain. We used 133 volcanoes on Syria Planum that are covered by Mars Orbiting Laser Altimeter (MOLA) and High Resolution Stereo Camera (HRSC) elevation data and 246 eSRP shields covered by the National Elevation Dataset (NED) for this comparison. Shields on Syria Planum average 191 +/- 88 m tall, 12 +/- 6 km in diameter, 16 +/- 28 km3 in volume, and have 1.7° +/- 0.8 flank slopes. eSRP shields average 83 +/- 44 m tall, 4 +/- 3 km in diameter, 0.8 +/- 2 km3 in volume, and have 2.5° +/- 1 flank slopes. Bivariate plots of morphometric characteristics show that Syria Planum and Snake River Plain low shields form the extremes of the same morphospace shared with some Icelandic olivine tholeiite shields, but are generally distinct from other terrestrial volcanoes. Cluster analysis of Syria Planum and Snake River Plain shields with other terrestrial volcanoes separates these volcanoes into one cluster and the majority of them into the same sub-cluster that is distinct from other terrestrial volcanoes. Principal component and cluster analysis of Syria Planum and Snake River Plain shields using height, area, volume, slope, and eccentricity shows that Syria Planum and Snake River Plain low-shields are similar in shape (slope and eccentricity). Apparently, these low shields formed by similar processes involving Hawaiian-type eruptions of low viscosity (mafic) lavas with fissure controlled eruptions, narrowing to central vents. Initially high eruption rates and long, tube-fed lava flows shifted to the development of small lava lakes that repeatedly overflowed, and on some with late fountaining to form steeper spatter ramparts. However, Syria Planum shields are systematically larger than those on the eastern Snake River Plain. The larger size of Syria Planum shields is likely due to the smaller gravity of Mars, requiring larger magma batches to generate sufficient buoyant force to overcome the strength of rocks in the lithosphere and rise to the surface. Thus, Syria Planum lavas erupt in larger volumes and at higher rates generating larger volcanoes with slightly smaller slopes.

Large-volume silicic eruptions are often evacuated from magma reservoirs which display gradients in composition, temperature, crystallinity, and volatile content. The 9.7 Ma Devine Canyon Tuff (DCT) of eastern Oregon represents such an eruption, with >300 km³ of compositionally zoned pyroclastic material deposited as a variably-welded ignimbrite. The ignimbrite displays homogenous bulk tuff major element compositions with a wide range of trace element compositions, allowing for the investigation of how these magmas were generated, stored, and modified in the magma reservoir by studying pumices which represent the primary magmas composing the DCT. Five pumices ranging from dacite to rhyolite bulk compositions were selected across the range of trace element compositions and were crushed and sieved to measure how crystallinity and mineral abundances change within each pumice at different particle size fractions. Single alkali feldspar and clinopyroxene crystals were analyzed using EMP and LA ICP-MS from each pumice. Physical results yielded a systematic decrease in crystallinity from 22% to 3% going from the dacite to the most evolved rhyolite composition, with the highest crystallinity occurring between <991-425 microns for all pumices analyzed. The dacite pumices displayed a glomerocrystic texture not observed in rhyolite pumices. Two populations of crystals were distinguished using single crystal chemical data, one belonging to the rhyolitic magmas and another belonging to the dacitic magma. Acquired mineral data have relevance for how strongly zoned with regard to trace elements the rhyolitic magmas of the DCT were, how these magmas were generated, and how they were stored within the magma reservoir. Applying melt extraction models to explain observed patterns in trace element compositions between pumices is problematic. In this model, the observed range of trace elements in rhyolite pumices would be attributed to two separate melt extraction events from an intermediate crystal mush where the first expulsion of melt from the mush produced the most evolved rhyolite composition and a second expulsion coupled with partial melting produced a second rhyolite with an indistinguishable major element composition but less evolved trace element composition. Mixing of these two rhyolite end members would then be needed for generating the range of intermediate rhyolite compositions. Magma mixing modeled using a mixing equation produced a poor fit for trace elements, suggesting the range of observed trace element compositions cannot be solely generated through the mixing of the extracted rhyolite melts but require processes that subsequently modify the mixed rhyolite compositions. The occurrence of crystal aggregates in the dacite may represent fragments of the crystal mush. However, the dacite was unlikely produced by partial remelting of the crystal mush, generating a less evolved, more intermediate bulk composition. In summary, mush extraction combined with partial melting of the crystal mush and mixing of compositional end members cannot fully explain the trace element patterns observed in the DCT pumices thus warranting further study.

The end-member types of shallow magmatic intrusions comprise cone sheets and dykes. These propagate from their source magma chamber towards the Earth’s surface. The propagation of magma within the shallow part of the volcano plumbing system produces surface deformation and seismicity, signs of volcanic unrest. Studying surface displacement using GPS and InSAR, geodetic modelling, fitting modelled data to real displacements, and inversion is regularly used to understand the processes in the subsurface. There is no possibility in nature to validate the assumptions of these models. However, using analogue modelling, it is possible to reproduce cone sheets and dykes in a controlled environment and study the associated surface deformation. This thesis tests the hypothesis that the two end-member types of magmatic sheet intrusions produce specific patterns of surface deformation. The analogue model surface is documented using two different monitoring setups: moiré monitoring and photogrammetry. The moiré method (dataset 1) consists of 43 experiments, 19 of which were dykes, 22 were cone sheets, and 2 were classified as hybrids. Photo- grammetry (dataset 2) was applied in 8 experiments, 3 of which produced cone sheets and 5 dykes. Dataset 1 successfully identified surface deformation patterns specific to the two intrusion types. Cone sheets develop in a gradual linear fashion, while the dykes exhibit a two-phase behaviour. The first phase shows little deformation until about halfway through the experiment duration when rapid deformation starts to occur. The point of maximum uplift, in both intrusion types, indicates the area of eruption from an early stage. Dataset 2 primarily evaluated the benefits of using the photogrammetric method. It successfully resolved horizontal components of displacement making it possible to study brittle defor- mation. As Dataset 2 consists of a limited amount of experiments, the results cannot be considered conclusive. However, they indicate that characteristic patterns of brittle deformation exist for the two types. Future improvements in this field include studying effects of topography and anisotropy on the surface deformation of the analogue models. Improvements in temporal and spatial resolution in the monitoring methods used to study surface displacement in nature is needed to perform analyses, similar to the ones presented here, on real surface deformation. The misfit of the surface deformation seen in numerical models compared to analogue models indicate that sheet intrusion propagation is not yet fully understood.
När magma rör sig från magmakammare mot jordytan i den ytliga delen av det underjordiska system av magma som finns under vulkaner, bildas ytdeformation. Genom att studera ytdeformationen med hjälp av GPS och InSAR samt numerisk modellering försöker forskare förstå dessa underjordiska processer för att förutspå framtida utbrott. Dessvärre finns ingen möjlighet att undersöka huruvida dessa numeriska modeller faktiskt överensstämmer med naturen. I gamla utdöda vulkaner som eroderats ner kan man se vulkanens inre där det finns stelnade, magmafyllda sprickor, så kallade gångar. Tyvärr ger detta dock ingen inblick i hur gångarnas bildning återspeglades i ytan. Detta kan man undersöka med hjälp av analoga modeller där det är möjligt att skapa likartade intrusioner i en kontrollerad labb-miljö och studera den tillhörande ytdeformationen. Denna avhandling undersöker hypotesen att de två huvudsakliga typerna av ytliga magmatiska gångar skapar specifika identifierbara mönster av ytdeformation. Detta testas genom att dokumentera den analoga modellens yta alltjämt som intrusionerna bildas med hjälp av två olika övervaknings- metoder. Den första metoden lyckades identifiera mönster som är specifika för de två olika typerna. Den högsta punkten på den deformerade ytan kan användas för att förutspå den plats där framtida utbrott kommer att ske i båda typerna. Den andra metoden lyckades urskilja dem horisontella komponenterna av förskjutning som gör det möjligt att studera den spröda deformation som utvecklas på ytan. Resultaten tyder på att karakteristiska mönster av spröd deformation existerar för de två typerna. För att förbättra de analoga modellerna måste man undersöka hur en mer topografiskt varierad yta påverkar den bildade deformation samt en skorpa som inte är helt homogen. Vid jämförelse mellan numeriska modeller och analoga modeller sågs en stor skillnad som tyder på att vi ännu inte förstår hur magma rör sig genom jordskorpan. Framtida användning av analyserna presenterade i denna avhandling kräver en förbättring av upplösningen på systemen som används till vulkanövervakning i naturen.

Mineral chemistry and petrography of basalts from the Kimama drill core recovered by Hotspot: Snake River Scientific Drilling Project, Idaho establish crystallization conditions of these lavas. Twenty-three basalt samples, from 20 individual lava flows were sampled from the upper 1000 m (of the 1912 m drilled) core drilled on the axis of the Snake River Plain, and represent approximately 3 m.y. of volcanism (rocks at the bottom of the hole are ~6 Ma). Rock from the upper 1000 m are typically fresh, while those lower in the core are more altered and are less likely to preserve fresh phenocrysts to analyze. Intratelluric phenocrysts (pre-eruption) are: olivine, plagioclase and Cr-spinel inclusions in olivine and plagioclase; groundmass phases (post-eruption) are: olivine, plagioclase, clinopyroxene, magnetite and ilmenite. Olivine core compositions range from Fo84-68, plagioclase cores range from An80-62, clinopyroxene ranges in composition from Wo47-34, En47-28, Fs30-15, spinel inclusions are Cr (up to 20 wt % Cr2O3) and Al-rich (up to 35 wt % Al2O3) and evolve to lower concentrations of Cr and Al and higher Fe and Ti, chromian titanomagnetite to magnetite, and ilmenite are groundmass oxide phases. Thermobarometry of Kimama core basalts indicates that the phenocryst phases crystallized at temperatures of 1155 to 1255°C at depths of 7 to 17 km, which is within or near the seismically imaged mid-crustal sill. Plagioclase hygrometry suggests that these lavas are relatively anhydrous with less than 0.4 wt % H2O. Groundmass phases crystallized at lower temperatures (<1140°C) after eruption. Oxygen fugacity inferred from Fe-Ti oxide equilibria is at or just below the QFM buffer. The origin of the basaltic rocks of the Snake River Plain has been attributed to a mantle plume or to other, shallow mantle processes. Mineral and whole rock major and trace element geochemistry of the olivine tholeiites from the Kimama core are used to distinguish between these two sources (deep or shallow mantle). Whole rock compositions were corrected for plagioclase and olivine fractionation to calculate primary liquids to estimate mantle potential temperatures. Olivine phenocrysts have the pyroxenite source characteristics of low Mn and Ca, but a peridotite source characteristic of low Ni. Thus, trace element models were used to test whether there is pyroxenite in the source of the Snake River Plain basalts, as hypothesized for Hawaii and other plume-related hotspots (e.g., Sobolev et al., 2005; Herzberg, 2011). Olivine chemistry and trace element models establish that the basalt source is a spinel peridotite, not a pyroxenite. The average mantle potential temperature obtained for these samples is 1577°C, 177°C hotter than ambient mantle, suggesting that the basaltic liquids were derived from a thermal plume. Silica activity barometry shows that melt segregation occurs between 80 and 110 km depth, which is within or very near the spinel stability field, and suggests that the lithosphere has been eroded by the plume to a maximum depth of 80 km, and recent mantle tomography suggests that it may be even thinner.

In this study, connections between chemical composition, eruption style, and topographic features of two shield volcanoes on the Snake River Plain, Idaho are examined. These relationships may then be applied to understanding silicate volcanic features throughout the inner solar system. Despite their similar ages and geographic locations, two young basaltic shield volcanoes—Kimama Butte (87 Ka) and Rocky Butte (95 Ka)—have strikingly different topographic profiles. The Kimama Butte shield has a diameter of 9 km and a height of 210 m. In contrast, Rocky Butte has a broad 36 km topographic shield that rises 140 m with less than 1° slopes. The vent crater at Rocky Butte developed as a large lava blister inflated and then collapsed forming a crater in which a lava lake developed. Little spatter accumulated throughout the eruption. In contrast, high spatter mounds and spatter-fed flows flank the main summit crater at Kimama Butte. Major- and trace-element compositions of the basaltic lavas are similar at the two shields, but distinct in Ni and Al2O3. The lavas range in TiO2 concentrations from 2.6–4.5 wt.% for Kimama Butte and 2.6–4.3 wt.% for Rocky Butte. These ranges can be related to magma evolution by fractional crystallization involving plagioclase and olivine without clinopyroxene. Compositions of the pre-eruptive phenocrysts are also similar at both shields but show variation with evolution. Olivine cores in the more primitive lavas are more Mg-rich (Fo80-72) than those in the evolved rocks (Fo65-55). Plagioclase cores are similarly more calcic in the more primitive flows (An78-68) than in the evolved ones (An65-52). Like other olivine-tholeiites on the Snake River Plain, the fO2 and fH2O were probably low with fO2 at -2△QFM and 0.1 wt.% H2O. Pressure of crystallization estimated from MELTS models is less than 3 kbar (~10 km deep). Calculated temperatures and magma viscosities overlap at both Kimama Butte (1226 to1147°C and 158 to14 Pa·s) and Rocky Butte (1251 to 1145°C and 75 to 8 Pa·s). However, Kimama Butte magma viscosities extend ~80 Pa·s higher than those for Rocky Butte lavas. The higher magma viscosities are the result of higher phenocryst proportions in spatter and spatter-fed lavas concentrated near the vent. Because lava temperature, volatile content, and chemical composition overlap at the two volcanoes, they are probably not important controls of shield-volcano morphology. This suggests that steep-capped shields are not created as a simple function of having more silicic lavas. Melt viscosities are also similar, but Rocky Butte lacks the phenocryst-rich (>30 vol %), higher magma viscosity lavas and the high spatter ramparts that form the cap at Kimama Butte. Thus, we conclude that eruption style and phenocryst content play the most important role in developing a low-shield volcano summit. Where eruptions shifted from lava lake overflow and tube development to late fountaining with short spatter-fed phenocryst-rich flows, steeper, higher shields develop.

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.

La tesis se enmarca en la relación entre espacios naturales protegidos, turismo y desarrollo sostenible. Y lo hace desde la óptica de la planificación de las prácticas turísticas, un tema bastante novedoso en nuestro país y que está de plena actualidad. Los objetivos fundamentales de la investigación son los siguientes:
Determinar, de manera genérica y en clave de sostenibilidad, el papel del turismo en los ENP españoles.
Estudiar con detalle dos instrumentos de planificación del turismo en las áreas protegidas españolas: la Carta Europea del Turismo Sostenible en los espacios protegidos y los Planes de Desarrollo Sostenible andaluces derivados de la Ley 2/1989.
Evaluar el alcance de dichos instrumentos en dos territorios concretos: el Parque Natural de la Zona Volcánica de la Garrotxa (Girona) y el Parque Natural Cabo de Gata-Níjar (Almería).
The PhD thesis framework is the connection between protected areas, tourism and sustainable development. The main approach is the Tourism Planning, a quite new and current topic in our country. The research has got the following main aims:
To set the role of tourism in the Spanish protected areas, both in general and under a key of sustainability.
To study in great detail two Tourism Planning tools in the Spanish protected areas: the European Charter for Sustainable Tourism and the Sustainable Development Plans in Andalucía which are a requirement from Law 2/1989.
To avaluate the scope of both tools in two specific territorios: the Zona Volcànica de la Garrotxa Nature Park (in Girona) and the Cabo de Gata-Níjar Nature Park (in Almería).

The Glass Buttes volcanic complex is a cluster of bimodal (basalt-rhyolite), Miocene to Pleistocene age lava flows and domes located in Oregon's High Lava Plains province, a broad region of Cenozoic bimodal volcanism in south-central Oregon. The High Lava Plains is deformed by northwest-striking faults of the Brothers Fault Zone, a diffuse, ~N40°W trending zone of en echelon faults cutting ~250 km obliquely across the High Lava Plains. Individual fault segments within the Brothers Fault Zone are typically <20 km long, strike ~N40°W, have apparent normal separation with 10-100 m throw. A smaller population of ~5-10 km long faults striking ~N30°E exhibits mutually crosscutting relationships with the dominant northwest striking faults. Basaltic volcanic rocks in the Glass Buttes area erupted during the late Miocene and Pleistocene. The oldest and youngest lavas are 6.49±0.03 Ma and 1.39±0.18 Ma, respectively, based on ⁴⁰Ar/³⁹Ar ages of five basaltic units. Numerous small mafic vents both within and around the margins of the main silicic dome complex are commonly localized along northwest-striking faults of the Brothers Fault Zone. These vents erupted a diverse suite of basalt to basaltic andesite lava flows that are here differentiated into 15 stratigraphic units based on hand sample texture and mineralogy as well as major and trace element geochemistry. The structural fabric of the Glass Buttes area is dominated by small displacement, discontinuous, en echelon, northwest-striking fault scarps that result from normal to slightly oblique displacements and are commonly linked by relay ramps. Northwest alignment of basaltic and rhyolitic vents, paleotopography, and cross-cutting relationships suggest these faults have been active since at least 6.49±0.03 Ma, the age of the rhyolite lavas in the eastern Glass Buttes are. Faults displace Quaternary sedimentary deposits indicating these structures continue to be active into the Quaternary. Long-term extension rates across northwest-striking faults calculated from 2-5 km long cross section restorations range from 0.004 – 0.02 mm/yr with an average of 0.12 mm/yr. A subordinate population of discontinuous northeast-striking faults form scarps and exhibit mutually cross-cutting relationships with the dominant northwest-striking population. Cross-cutting relationships indicate faulting on northeast-striking faults ceased sometime between 4.70±0.27 Ma and 1.39±0.18 Ma. Gravity data at Glass Buttes reveals prominent northwest- and northeast-trending gravity gradients that closely parallel the strikes of surface faults. These are interpreted as large, deep-seated, normal faults that express themselves in the young basalts at the surface as the discontinuous, en echelon fault segments seen throughout the study area and BFZ in general. Elevated geothermal gradients are localized along these deep-seated structures at two locations: (1) where northwest- and northeast-striking faults intersect,(2) along a very prominent northwest-striking active normal fault bounding the southwest flank of Glass Butte. High average heat flow and elevated average geothermal gradients across the High Lava Plains, and the presence of hydrothermal alteration motivated geothermal resource exploration at Glass Buttes. Temperature gradient drilling by Phillips Petroleum and others between 1977-1981 to depths of up to 600 m defined a local geothermal anomaly underlying the Glass Buttes volcanic complex with a maximum gradient of 224 °C/km. Stratigraphic constraints indicate that near-surface hydrothermal alteration associated with mercury ores ceased before 4.70±0.27 Ma, and is likely associated with the 6.49±0.03 Ma rhyolite eruptions in the eastern part of Glass Buttes. The modern thermal anomaly is not directly related to the pre-4.70±0.27 Ma hydrothermal system; rather it is likely a result of deep fluid circulation along major extensional faults in the area.
Graduation date: 2013
Includes accompanying DVD with digital data supplement (8 GB).

This dissertation analyzes the spatial distribution and kinematics of the Late Cenozoic Basin and Range (BR) and cross normal fault (CF) systems and their related graben basins around the Snake River Plain (SRP), and investigates the spatio-temporal patterns of lavas that were erupted by the migrating Yellowstone hotspot along the SRP, applying a diverse set of GIS-based spatial statistical techniques. The spatial distribution patterns of the normal fault systems, revealed by the Ripley's K-function, display clustered patterns that correlate with a high linear density, maximum azimuthal variation, and high box-counting fractal dimensions of the fault traces. The extension direction for normal faulting is determined along the major axis of the fractal dimension anisotropy ellipse measured by the modified Cantor dust method and the minor axis of the autocorrelation anisotropy ellipse measured by Ordinary Kriging, and across the linear directional mean (LDM) of the fault traces. Trajectories of the LDMs for the cross faults around each caldera define asymmetric sub-parabolic patterns similar to the reported parabolic distribution of the epicenters, and indicate sub-elliptical extension about each caldera that may mark the shape of hotspot’s thermal doming that formed each generation of cross faults. The decrease in the spatial density of the CFs as a function of distance from the axis of the track of the hotspot (SRP) also suggests the role of the hotspot for the formation of the cross faults. The parallelism of the trend of the exposures of the graben filling Sixmile Creek Formation with the LDM of their bounding cross faults indicates that the grabens were filled during or after the CF event. The global and local Moran’s I analyses of Neogene lava in each caldera along the SRP reveal a higher spatial autocorrelation and clustering of rhyolitic lava than the coeval basaltic lava in the same caldera. The alignment of the major axis of the standard deviational ellipses of lavas with the trend of the eastern SRP, and the successive spatial overlap of older lavas by progressively younger mafic lava, indicate the migration of the centers of eruption as the hotspot moved to the northeast.