The San Rafael Volcanic Field, Utah, is a 4.6 Ma extinct monogenetic field that is found in the Northern Transition Zone of the Colorado Plateau. The field has been eroded, leaving the dikes, conduits, and sills visible. Within the sills we see evidences of immiscibility in the form of an intermediate syenite (~50 wt% SiO2) enclosed in a mafic shonkinite (~48 wt % SiO2). Field relations indicate that sills were formed due to single events (Richardson et al., 2015), which makes in-situ differentiation the process at the origin of both rock types. Geochemical data supports differentiation of syenite and shonkinite from a single melt. The syenites are more enriched in LREE than shonkinites. The rocks are enriched in LREE compared to an OIB source, indicating melting of a hydrated lithosphere interacting with an asthernospheric garnet peridotite. Olivine with a composition of Fo80-90 further support asthernospheric origin, and pyroxenes indicate that depth of crystallization would have begun around 33 Km, indicating that the melt would have pooled at the base of the crust as it traveled, supporting base of the lithosphere origins. Rhyolite-MELTS modeling further supports differentiation within the sills as the formations of feldspars, biotite and hornblende did not occur until ~800m which would have allowed for fractional crystallization to occur, leading to the immiscibility process and resulting formation of syenite and shonkinite.

This thesis examines different methods of communicating volcanic hazards to the population of Flagstaff, Arizona using the results of a recent lava flow hazard assessment of the nearby San Francisco Volcanic Field (SFVF). Harburger (2014) determined that given a lava flow originating in the SFVF, there is a statistical probability that it will inundate the city of Flagstaff or even originate from a vent within the city limits. Based on the recurrence rates for the most recent eruptions (3 x 10-4/year), the probability of lava flow inundation in Flagstaff is 1.1 x 10-5 per year. This study considers the effects of three different communication methods on participants’ perceived risk. The methods were administered through a questionnaire and included a statement of probability of lava flow inundation per year, a statement of probability over a 100 year period, and an interactive lava flow map derived from the results of the lava flow hazard assessment. Each method was followed by questions gauging level of concern. Questionnaires were administered to 213 Flagstaff residents over a two week period in February 2015. Results showed that levels of concern, rated from 1 (not concerned) to 5 (very concerned), varied based on each method of communication. The method with the greatest effect on perceived risk was the simulated lava flow map, while the first method with a one year odds resulted in a statistically lower mean rating of concern. It is suggested that the best way to change levels of perceived risk when communicating lava flow hazards includes a combination of comprehensible odds and visual aids. Further studies could also include visualization of the entire eruption scenario, including time scales and other volcanic hazards, which may have more effect on concern than a simplified visualization of lava flows.

Instances of fault-controlled monogenetic volcanism across the subduction arc of the Central Andes at ~ 23°S illuminate the nature of different parental melts being delivered to the crust. Evidence of magmatic history is preserved in bulk rock geochemistry, the content of melt inclusions, and mineral compositions. Volcanism in this region is dominated by felsic and intermediates lavas as the thickened crust (55 – 65 km) and vast volumes (> 500,000 km3) of mid-crustal magma beneath the Altiplano-Puna high plateau region prevent mafic magmas from reaching the surface (Davidson & De Silva, 1991; Beck et al., 1996; Perkins et al., 2016). However, small volumes of relatively undifferentiated lava have been delivered from the lower crust to the surface along zones of crustal weakness without extensive processing by crustal assimilation and/or extended storage in sub-volcanic magma chambers. Monogenetic eruptions of less-differentiated lava provide important constraints on compositions normally obscured by crustal processing in the Central Andes. Basaltic andesite sampled within the frontal arc (Cerro Overo maar) is a regional mafic end-member and approximates the composition of parental arc magmas derived from partially-molten lower crustal regions where mantle-derived magmas interact with the surrounding lithosphere and undergo density differentiation (MASH zones). Basaltic olivine-hosted melt inclusions from Cerro Overo provide a glimpse of less-evolved melt composition from this region and suggest mobilization of MASH magma by injection of basaltic melt. Basaltic andesite sampled from the eastern (back) margin of the frontal arc (Puntas Negras – El Laco) is another regional mafic endmember, representing a mantle-derived magma composition that is transitional between subduction arc magmatism and intraplate magmatism of the back-arc. The internal crystal architecture revealed by major and trace element zoning of olivine phenocrysts indicates Cerro Overo magma experienced continuous ascent, while Puntas Negras magma experienced a brief period of stalling or storage near the brittle-ductile transition zone (~ 25 km). Aphyric intermediate monogenetic lavas sampled west of (before) the frontal arc display Adakite-like signatures (e.g. high Sr/Y and Sm/Yb) represent small amounts of melt generated with a significant contribution from direct melting of the metabasaltic slab or delaminated lithospheric root at high pressure. These three magmatic regimes sampled at monogenetic centers approximate different end-member compositions being delivered to the lower crust of the Central Andes from which the range of intermediate main arc volcanism in the Altiplano-Puna region is ultimately derived.

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This study serves as a first step towards a comprehensive hazard assessment for the San Francisco volcanic field in northern Arizona, which can be applied to local response plans and educational initiatives. The primary goal of this thesis is to resolve the conditional probability that, given a lava flow effusing from a new vent in the San Francisco volcanic field, it will inundate the city limits of Flagstaff. The spatial distribution of vents within the San Francisco volcanic field was analyzed in order to execute a lava flow simulation to determine the inundation hazard to Flagstaff. The Gaussian kernel function for estimating spatial density showed that there is a 99% chance that a future vent will be located within a 3.6 x 109 m2 area about 20 kilometers north of Flagstaff. This area contains the location of the most recent eruption at Sunset Crater, suggesting that the model is a good predictor of future vent locations. A Monte Carlo analysis of potential vent locations (N = 7,769) showed that 3.5% of simulated vents generated lava flows that inundated Flagstaff, and 1.1% of simulated vents were located within the city limits. Based on the average recurrence rate of vents formed during the Brunhes chronozone, the aggregate probability of lava flow inundation in Flagstaff is 1.1 x 10-5 per year. This suggests that there is a need for the city to plan for lava flows and associated hazards, especially forest fires. Even though it is unlikely that the city will ever have to utilize such a plan, it is imperative that thorough mitigation and response plans are established now-- before the onset of renewed volcanic activity.

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Submitted by Socorro Pontes (socorrop@ufersa.edu.br) on 2017-06-29T12:11:05Z No. of bitstreams: 1 BrunaLFF_DISSERT.pdf: 1489360 bytes, checksum: b80c12e94b27433d39f8e4d7c7b1d47e (MD5) / Made available in DSpace on 2017-06-29T12:11:06Z (GMT). No. of bitstreams: 1 BrunaLFF_DISSERT.pdf: 1489360 bytes, checksum: b80c12e94b27433d39f8e4d7c7b1d47e (MD5) Previous issue date: 2017-02-21 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Haemulon plumierii are coastal fish that inhabit waters from the Chesapeake Bay - US, Gulf of Mexico, Caribbean and the entire coast of Brazil. Fish are the aquatic vertebrates that have the highest rates of parasitism and use different reproductive tactics in their life strategy to maximize reproduction and ensure the survival of their offspring to adulthood. The present work verified whether the ectoparasitism by monogenetic can influence the reproductive tactics of H. plumierii in marine waters in the North Atlantic Ocean Southwest (4º 50'57 ''S and 37º51'36''O), near the Rio Grande do Norte / Brazil, for that, the parasitic research of monogenetic was carried out and the study of the reproductive tactics of H. Plumierii. 240 copies were captured of H. plumierii hosts in the period from august 2015 to july 2016, with amplitudes of total weight between 84.5 to 517.5g and total length of 175 to 315mm. Monogenetics parasitized 106 H. plumierii fish among 240 examined, and 162 parasites were collected that were distributed in two subclasses: Monopisthocotylea and Polyopisthocotylea. Monopisthocotylea of the family Capsalidae in the genus Encotyllabe (75 in the gills and 9 in the skin) and Entobdella (1 in the gills and 17 in the skin); Polyopisthocotylea in the family Diclidophoridae in the genus Choricotyle (51 in the gills and 9 in the skin). H. plumierii was identified as a new host for the monogenéticos Encotyllabe sp., Entobdella hipoglossi, and Choricotyle sp., being the first record of the genus Entobdella in the family Haemulidae. The monogenetic parasites had a higher parasite preference for the gills, presenting low parasitic ecological indices. It was determined that H. plumierii are seasonal strategist fish in which males present greater total weight, total length and number in relation to females, however, there were no significant differences. It was recorded that the H. plumierii species has the following reproductive tactics: growth of the negative allometric type indicating a greater body increase in length than in weight; independent of this immature (young) stage it was verified macroscopically that adults have three stages of gonadal development (in maturation, mature and emptied) during the reproductive cycle; this animal altered its reproductive strategy, initiating reproductive development with precocity where the absolute fecundity was 52,123 oocytes with a synchronous spawning type in more than two groups; the reproductive period is comprised throughout the year with the highest occurrence in two moments in the months of march to june and the second of august to October. The present work reported that the species Haemulon plumierii is parasitized by monogenetic Monopisthocotylea and Polyopisthocotylea with low prevalence rates, medium intensity and average abundance, and that H. plumierii is a seasonal strategist where his reproductive tactics were not influenced by the parasitism of monogenetics in conditions of low parasitic ecological indices / Haemulon plumierii são peixes costeiros que habitam águas desde a Baía de Chesapeake - EUA, Golfo do México, Caribe e toda a costa do Brasil. Os peixes são os vertebrados aquáticos que apresentam os maiores índices de parasitismo e usam diferentes táticas reprodutivas em sua estratégia de vida para maximizar a reprodução e garantir a sobrevivência dos seus descendentes até a idade adulta. O presente trabalho verificou se o ectoparasitismo por monogenéticos pode influenciar as táticas reprodutivas de H. plumierii nas águas marinhas no Norte do Oceano Atlântico Sudoeste (4º 50’57’’S e 37º51’36’’O), próximo ao Rio Grande do Norte/Brasil, para isso, realizou-se a pesquisa parasitária de monogenéticos e o estudo das táticas reprodutivas de H. plumierii. Foram capturados 240 exemplares de hospedeiros H. plumierii no período de agosto de 2015 a julho de 2016, com amplitudes de peso total entre 84,5 a 517,5g e comprimento total de 175 a 315mm. Os Monogenéticos parasitaram 106 peixes H. plumierii entre 240 examinados, sendo coletados 162 parasitos que estavam distribuídos em duas subclasses: Monopisthocotylea e Polyopisthocotylea. Monopisthocotylea da família Capsalidae nos gêneros Encotyllabe (75 nas brânquias e 9 no tegumento) e Entobdella (1 nas brânquias e 17 no tegumento); Polyopisthocotylea na família Diclidophoridae no gênero Choricotyle (51 nas brânquias e 9 no tegumento). H. plumierii foi identificado como um novo hospedeiro para os monogenéticos Encotyllabe sp., Entobdella hipoglossi, e Choricotyle sp., sendo o primeiro registro do gênero Entobdella na família Haemulidae. Os parasitos monogenéticos apresentaram uma maior preferência parasitária pelas brânquias, apresentando baixos índices ecológicos parasitários. Determinou-se que H. plumierii são peixes estrategistas sazonais no qual os machos apresentam maior peso total, comprimento total e número em relação as fêmeas, contudo não ocorreram diferenças significativas. Registrou-se que a espécie H. plumierii possui as seguintes táticas reprodutivas: crescimento do tipo alométrico negativo indicando um incremento corporal maior em comprimento do que em peso; independente deste estádio imaturo (jovens) foi verificado macroscopicamente que os adultos possuem três estádios de desenvolvimento gonadal (em maturação, maduro e esvaziado) durante o ciclo reprodutivo; este animal alterou sua estratégia reprodutiva iniciando o desenvolvimento reprodutivo com precocidade onde a fecundidade absoluta foi de 52.123 ovócitos com um tipo de desova sincrônico em mais de dois grupos; o período reprodutivo está compreendido durante todo o ano com maior ocorrência em dois momentos nos meses de março a junho e o segundo de agosto a outubro. O presente trabalho registrou que a espécie Haemulon plumierii é parasitado por monogenéticos Monopisthocotylea e Polyopisthocotylea com baixos índices de prevalência, intensidade média e abundância média, e que H. plumierii é um estrategista sazonal onde suas táticas reprodutivas não sofreram influência pelo parasitismo de monogenéticos nas condições de baixos índices ecológicos parasitários / 2017-06-29

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