Sedimentos em suspensão representam um dos principais fatores que afetam a qualidade dos sistemas aquáticos no mundo; influenciam os processos geomórficos de construção da paisagem e podem indicar problemas de erosão e perda de solo na bacia hidrográfica contribuinte. O seu monitoramento espacial e temporal é fundamental nas atividades de gestão ambiental de áreas costeiras. Nesse sentido, a hipótese básica desta pesquisa é que o padrão espacial e temporal de plumas de sedimentos costeiras associado ao regime hidrológico do rio pode ser caracterizado a partir de imagens orbitais de média resolução espacial. Para comprová-la, elegeu-se a foz do rio Paraíba do Sul como área de estudo para definição e teste metodológico, e formulou-se como principal objetivo mapear qualitativamente a pluma costeira deste rio a partir de imagens Landsat 5 e CBERS-2, ao longo do período compreendido entre 1985 e 2007. As datas avaliadas foram criteriosamente definidas através de três estratégias de análise, totalizando cinqüenta imagens. Pesquisa bibliográfica e avaliação da resposta espectral da feição de interesse nas imagens selecionadas consistiram nas etapas principais da definição da metodologia. As plumas foram então identificadas, mapeadas e extraídas; posteriormente, suas características espaciais e temporais foram analisadas por intermédio de sistemas de informação geográfica e avaliadas em conjunto com dados históricos de vazão. Os resultados indicam que a banda do vermelho forneceu uma melhor discriminação interna da pluma, sendo, portanto, utilizada como base para as análises realizadas neste trabalho. Com exceção do procedimento de correção atmosférica, a metodologia proposta consiste na utilização de técnicas simples de processamento digital de imagens, baseadas na integração de técnicas semi-automáticas e de análise visual. A avaliação do padrão dos sedimentos e dos mapas temáticos qualitativos de concentração de sedimentos em suspensão indica a forte diferenciação existente entre cenários representativos de épocas de cheia e seca do rio. Análises espaciais do comportamento da pluma contribuem ainda para um maior conhecimento do espaço geográfico, fornecendo subsídios aos mais variados setores do planejamento e gestão ambiental. / Suspended sediments are a major factor affecting water quality in aquatic ecosystems of the world; they do influence the geomorphological processes of environmental formation and may indicate erosion problems and loss of ground on the contributing watershed. Its spatial and temporal monitoring is fundamental in the activities of the environmental management of the coastal areas. In that direction, the basic hypothesis of this research is that the spatial and temporal pattern of coastal plumes of sediments associated to the hydrological regime of the river may be characterized from orbital images of medium spatial resolution. To prove this, it was elected the mouth of Paraiba do Sul river as study area for defining and testing the methodology, which was formulated as principal purpose to map qualitatively the coastal plumes of this river from the images of Landsat 5 and CBERS-2, from the period between 1985 and 2007. The evaluated dates were defined with criteria through three strategies of analysis, totaling fifty images. Literature review and evaluation of the spectral response of the feature of interest consisted on the main steps of the definition of the methodology. The plumes were so identified, mapped and extracted; afterward, its spatial and temporal characteristics were analyzed by geographical information systems and evaluated together with historical data of river discharge. The results indicate that the red band yielded a better internal discrimination of the plume, being, therefore, used as basis to the analyses realized on this work. With exception of the procedure of atmospheric correction, the methodology proposal consists on the utilization of simple techniques of digital processing of images, based on the integration of semi-automatic and visual analyses techniques. The evaluation of the sediments pattern and qualitative thematic maps of suspended particulate matter indicates the strong differentiation existing between scenarios representing the periods of high and low waters of the river. Spatial analyses of the behavior of the plumes even contribute to a better knowledge of the geographical space, supplying subsidies to the most assorted sectors of environmental planning and management.

A major part of the terrestrial sediment in the ocean comes from the land via river plume. There are four stages in sediment dispersal from rivers into the sea: supply via plume, initial deposition, resuspension and transport by waves and currents or by the slope failure, and long-term net accumulation. We can understand the dispersion and transport of the river plume by in situ observations of hydrodynamic of the plume field. Therefore, it is helpful to study river plume hydrodynamics, such as winds, tides, waves, and currents. The purpose of this study is to identify the type of plume dynamics by analyzing the temporal and spatial variability of hydrological structures observed around the Gaoping River mouth. We observed the bottom and surface time series of temperature, salinity, turbidity, suspended sediment concentration, and velocity profile by instrument mounted at the tetrapods and a moored buoy during July 28 to 30 in 2009 and July 30 to August 2 in 2011. Besides, we investigated the spatial structures of the river plume in Gaoping River mouth by using a fishing boat in 2009. We also acquired satellite images to assist our study. The results showed that the river discharges during 2009 was lower than daily average discharge. Combined the temporal and spatial observations and satellite images, we determined that the river plume turned west during the ebb tide was influenced by Coriolis force and winds. The buoyancy-driven current velocity was 0.15 m/s and the maximum of wind-driven current velocity was 0.30 m/s. The wind strength index (Ws) determines whether a plume¡¦s along-shelf flow is in a wind-driven or buoyancy-driven state. Ws is the ratio of the wind-driven and buoyancy-driven along-shelf velocities. If |W_s | > 1 on average the wind velocity more than 5.9 m/s. The wind velocity reached this threshold during most of the ebb periods, and around that value in the flood time. Flood currents combined with cross-shore wind pushed the river plume to swing to the east. The data were analyzed by empirical orthogonal function (EOF) analysis. The results indicated that winds and waves were the main factors influencing plume dynamics during low-discharge period. During the field experiment in 2011, the river discharge was greater than daily average discharge. The buoyancy-driven and the maximum of wind-driven current velocities were 0.30 and 0.12 m/s, respectively. The wind velocity did not reach the threshold that was 11.67 m/s. The buoyancy-driven current was more significant than wind-driven current. By analyzing the ocean color of satellite images, the river plume was spreading from the river mouth and toward west during ebb. The time series data also showed that there was plume signal at the same time. The average cross-shore current velocity was 0.52 m/s, being larger than the buoyancy-driven current. Therefore, the tide was the main factor deciding where the plume discharged. The first eigemode of EOF suggested that current was the most important factor influencing plume dynamics during high-discharge period. The second eignmode described the dominant influence of wind.

Volcanogenic lightning has a long documented history in the scientific field, though its origins are still poorly understood. The interactions leading to electrification of ash plumes is essentially a function of the microphysics controlling and affecting ash particle collisions. This thesis presents measurements made on charged particle interactions in a fluidized bed, with large-scale applications to the phenomenon of volcanogenic lightning and charged particle dynamics in volcanic plumes. Using a fluidized bed of ash samples taken from Ecuador's Volcán Tungurahua, particles are introduced to a collisional environment, where they acquire an associated polarity. A charged copper plate is used to collect particles of a given polarity, and particle size distributions are obtained for different weight fractions of the ash. It is observed that relatively smaller particles acquire a net negative charge, while larger particles in the sample charge positively. This is a well-documented occurrence with perfectly spherical, chemically identical samples, but this work represents one of the first applications of the principle to volcanic ash. Image analysis is preformed to determine the size distribution associated with specific polarities, and the associated minimum charge on each particle is calculated based on the plate collection height and particle size. We also present results that demonstrate the relationship between particle collisions and the amount of charge exchanged. Using techniques developed to examine the collision rate within a flow, combined with the charging rates determined from this experiment, we determine a maximum charge exchange rate of 1.28±0.23 electrons transferred per collision.

For the past four decades, Mars missions have relied on Viking heritage technology for supersonic descent. Extending the use of propulsion, which is required for Mars subsonic deceleration, into the supersonic regime allows the ability to land larger payload masses. Wind tunnel and computational experiments on subscale supersonic retropropulsion models have shown a complex aerodynamic flow field characterized by the interaction of underexpanded jet plumes exhausting from nozzles on the vehicle with the supersonic freestream. Understanding the impact of vehicle and nozzle configuration on this interaction is critical for analyzing the performance of a supersonic retropropulsion system, as deceleration will have components provided by both the aerodynamic drag of the vehicle and thrust from the nozzles. This investigation focuses on the validity of steady state computational approaches to analyze supersonic retropropulsion flowfield structures and their effect on vehicle aerodynamics. Wind tunnel data for a single nozzle and a multiple nozzle configuration are used to validate a steady state, turbulent computational fluid dynamics approach to modeling supersonic retropropulsion. An analytic approximation to determine plume and bow shock structure in the flow field is also developed, enabling rapid assessment of flowfield structure for use in improved grid generation and as a configuration screening tool. Results for both the computational fluid dynamics and analytic approaches show good agreement with the experimental datasets. Potential limitations of the two methods are identified based on the comparisons with available data. Six additional geometries are defined to investigate the extensibility of the analytical model and determine the variation of supersonic retropropulsion performance with configuration. These validation geometries are split into two categories: three geometries with nozzles located on the vehicle forebody at varying nozzle cant angles, and three geometries with nozzles located on the vehicle aftbody at varying nozzle cant angles and number of nozzles. The forebody nozzle configurations show that nozzle cant angle is a significant driver in performance of a vehicle employing supersonic retropropulsion. Aerodynamic drag preservation for a given thrust level increases with increasing cant angle. However, increasing the cant angle reduces the contribution of thrust to deceleration. The tradeoff between these two contributions to the deceleration force is examined, noting that performance improvements are possible with modest nozzle cant angles. Static pitch stability characteristics are investigated for the lowest and highest cant angle configurations. The aftbody nozzle configuration results show that removing the plume flow from the region forward of the vehicle results in less interaction with the bow shock structure. This impacts aerodynamic performance, as the surface pressure remains relatively undisturbed for all thrust values examined. Static pitch stability characteristics for each of the aftbody nozzle configurations are investigated; noting that supersonic retropropulsion for these configurations exhibits a transition point from static stability to instability as a function of this center of mass location along the axis.

The Mount Somers Volcanic Group (MSVG) and Mandamus Igneous Complex (MIC) are the magmatic manifestations of the transition from convergence to extension at the Gondwana margin, which culminated in the separation of New Zealand from Australia and Antarctica. The MIC has been correlated both geochemically and temporally with the Central Marlborough Igneous Province (CMIP). The MSVG and CMIP are located in the Eastern Province of New Zealand. The MSVG is restricted to the Rakaia terrane, whereas the CMIP is restricted to the Pahau terrane. The Rakaia and Pahau terranes are thick accretionary complexes, which were strongly deformed as a result of prolonged subduction at the Gondwana margin. The Pahau terrane is the younger of the two and continued to be deposited and deformed until the abrupt cessation of subduction, which in the Marlborough sedimentary record occurred in the Motuan (100 - 105 Ma). Following the cessation of subduction, after an interval of 2-7 Ma of relative quiescence and subsidence of the Pahau terrane, the MSVG and MIC were erupted/emplaced. The production of MSVG and MIC magmas occurred simultaneously and the activity was of short-lived duration. SHRIMP geochronology yielded crystallisation ages of 97.0 ± 1.5 Ma to 98.0 ± 1.2 Ma from zircons separated from MSVG rhyolites. The SHRIMP ages are within error of the previously published Rb-Sr age for the MIC. The SHRIMP geochronology also confirmed the presence of inherited zircons which yielded ages consistent with their derivation from the Rakaia terrane. Ar-Ar geochronology confirmed the coeval nature of the MSVG and MIC magmatism, but yielded consistently younger ages (94.5 ± 3 Ma for the MSVG and 94.2 ± 1.7 Ma for the MIC). The systematic differences in ages obtained by SHRIMP and Ar-Ar are believed to be method-dependent. The MSVG comprises a calc-alkaline volcanic assemblage, which ranges in composition from basaltic-andesite lavas (SiO₂ = 54.5%) to high-silica rhyolites and ignimbrites (SiO₂ ≤ 78.1%). The MSVG had an original extent of at least 18 000 km². The magmas from the MSVG had high LILE/HFSE, high LILE/REE and moderately high LREE/HFSE which are characteristic of subduction derived magmas. Geochemical modelling suggests that the MSVG magmas were formed from partial melting of a subduction-modified mantle wedge, with high degrees of crustal assimilation. The assimilant had an isotopic composition similar to that of the Rakaia terrane, which is consistent with the geological setting of the MSVG. The MSVG has ⁸⁷Sr/⁸⁶Sri from 0.7055 to 0.7100 and ¹⁴³Nd/¹⁴⁴Ndi from 0.51254 to 0.51230 (ɛNd +0.5 to -4.2), which reflects varying degrees of contamination by Rakaia terrane. Radiogenic isotope modelling suggests that the MSVG end-members were derived from the same parent magma, which evolved through AFC processes from basaltic-andesite to rhyolite. The modelling strongly suggests that assimilation played a lesser role in the petrogenesis of the Malvern Hills magmas than in the petrogenesis of the other units. AFC modelling requires the degree of assimilation to increase as the magmas evolved. Oxygen isotope data are consistent with high degrees of crustal assimilation, and may indicate that the assimilant had higher ¹⁸O characteristics than the Rakaia terrane samples analysed. The MIC is an alkaline suite which ranges in composition from basalt and gabbro to syenite, trachyte and phono-tephrite. The MIC is interpreted to have formed from enriched asthenospheric mantle, with a composition similar to HIMU (²⁰⁶Pb/²⁰⁴Pbi ranges from 19.2 to 20.3). The samples range in isotopic composition from ⁸⁷Sr/⁸⁶Sri = 0.7030 to 0.7036, ¹⁴³Nd/¹⁴⁴Ndi = 0.51275 to 0.51268 (ɛNd +4.6 to +3.3). The range in isotopic composition is due to varying degrees of contamination by Pahau terrane, which reaches a maximum of 25% but in most samples is < 10%. The MIC is contaminated to a much lesser extent than the MSVG which is interpreted to be related to the thinner nature of the Pahau crust in the mid-Cretaceous. The latest phases of activity in the MIC were subjected to lower degrees of contamination which is interpreted to reflect the passage of magmas through pre-existing pathways. The onset of MSVG and CMIP magmatism coincided with the initiation of major rift-related depositional basins, and the eruption of the MSVG is demonstrably associated with normal faulting. The tectonic trigger responsible for the sudden onset of magmatism and rifting in the Eastern Province terranes was the detachment of the previously subducting slab following the cessation of subduction due to the arrival of the Hikurangi Plateau at the margin and the subsequent stalling of the Pacific spreading centre. The capture of the Gondwana margin led to the propogation of extension into the margin by the divergent Pacific plate. The ensuing extension aided the detachment of the subducting slab beneath the Eastern Province terranes. The slab-detachment promoted decompression melting of the sub-lithospheric mantle wedge to produce the MSVG magmas and triggered the ascent of asthenospheric mantle through the slab window, which melted through decompression to produce the CMIP magmatism. The asthenospheric mantle tapped by the slab detachment episode was highly enriched relative to N-MORB and is akin to the similar age HIMU-OIB affinity melts documented from Antarctica and Australia. The short-lived duration of activity is typical of slab-detachment related magmatism which occurs as a passive response to plate reconfiguration. The similarity in geochemistry of the MIC with OIB-affinity igneous centres in Australia and Antarctica implies an enriched mantle domain of large geographical extent. The distribution of relatively small volumes of OIB magmatism is suggestive of a fossil plume component, which was tapped in response to lithospheric extension producing relatively short-lived HIMU magmatism. The same fossil plume component has previously been implicated in the formation of the Cenozoic West Antarctic Rift System and may be responsible for the late Cretaceous magmatism in the Chatham Islands and Tertiary volcanics of the South Island of New Zealand.

abstract: This research investigates Earth structure in the core-mantle boundary (CMB) region, where the solid rocky mantle meets the molten iron alloy core. At long wavelengths, the lower mantle is characterized by two nearly antipodal large low shear velocity provinces (LLSVPs), one beneath the Pacific Ocean the other beneath Africa and the southern Atlantic Ocean. However, fine-scale LLSVP structure as well as its relationship with plate tectonics, mantle convection, hotspot volcanism, and Earth's outer core remains poorly understood. The recent dramatic increase in seismic data coverage due to the EarthScope experiment presents an unprecedented opportunity to utilize large concentrated datasets of seismic data to improve resolution of lowermost mantle structures. I developed an algorithm that identifies anomalously broadened seismic waveforms to locate sharp contrasts in shear velocity properties across the margins of the LLSVP beneath the Pacific. The result suggests that a nearly vertical mantle plume underlies Hawaii that originates from a peak of a chemically distinct reservoir at the base of the mantle, some 600-900 km above the CMB. Additionally, acute horizontal Vs variations across and within the northern margin of the LLSVP beneath the central Pacific Ocean are inferred from forward modeling of differential travel times between S (and Sdiff) and SKS, and also between ScS and S. I developed a new approach to expand the geographic detection of ultra-low velocity zones (ULVZs) with a new ScS stacking approach that simultaneously utilizes the pre- and post-cursor wavefield.. Strong lateral variations in ULVZ thicknesses and properties are found across the LLSVP margins, where ULVZs are thicker and stronger within the LLSVP than outside of it, consistent with convection model predictions. Differential travel times, amplitude ratios, and waveshapes of core waves SKKS and SKS are used to investigate CMB topography and outermost core velocity structure. 1D and 2D wavefield simulations suggest that the complicated geographic distribution of observed SKKS waveform anomalies might be a result of CMB topography and a higher velocity outermost core. These combined analyses depict a lowermost mantle that is rich in fine-scale structural complexity, which advances our understanding of its integral role in mantle circulation, mixing, and evolution. / Dissertation/Thesis / Ph.D. Geological Sciences 2012

[pt] Este trabalho apresenta uma investigação experimental do escoamento induzido pela interação entre uma pluma de bolhas e um escoamento cruzado oscilatório. Condições de escoamento similares podem ser encontrados em processos de aeração artificial utilizados na mitigação da poluição nos rios e na representação de vazamento de gás natural no fundo dos oceanos. No presente trabalho, ondas superficiais controladas foram inseridas em um canal de água para gerar oscilações na corrente do escoamento cruzado. As ondas foram geradas a partir de uma placa móvel na superfície da água e determinadas condições de escoamento instável foram selecionadas para a investigação. O ar foi injetado pelo fundo do canal para formar a pluma de bolhas. A técnica Particle Image Velocimetry (PIV) foi empregada para medir a velocidade do escoamento. Antes da estimativa da velocidade, as imagens foram pré-processadas aplicando-se rotinas desenvolvidas no Matlab a fim de distinguir as partículas traçadoras das bolhas de ar e criar máscaras dinâmicas para as imagens do sistema PIV. Assim, o campo vetorial de velocidade foi estimado utilizando algoritmos padrão do PIV. Além disso, as propriedades das bolhas, como tamanho e velocidade, também foram estimadas a partir das imagens adquiridas. Finalmente, foi analisada a interação entre a pluma de bolhas com o escoamento cruzado instável. / [en] This work presents an experimental investigation of the flow field induced by the interaction between a bubble plume and an oscillating cross flow. Similar flow conditions can be found in artificial aeration processes used for mitigation of pollution contamination in rivers and submarine outfalls in coastal areas. The mixing zone is highly dependent of the flow field near the plume hence the efficiency of aeration processes. In the present work, controlled surface waves were introduced to generate oscillations in streamwise and wall normal components of the cross flow. The waves were excited with a moving paddle and unsteady flow conditions were selected for the investigation. Air was injected in the bottom wall of the water channel to form the bubble plume. Particle Image Velocimetry (PIV) techniques were employed to measure the velocity flow field. Prior to velocity estimation, images were pre-processed using Matlab routines in order to distinguish tracer particles from air bubbles and to create a dynamic mask for the PIV images. Thus, the velocity vector field was estimated using standard PIV algorithms. In addition, properties of the bubbles, such as size and velocity, were also estimated from the acquired images. Finally, the interaction between the bubble plume with the unsteady cross flow was analyzed.

A suíte de xenólitos ultramáficos do Cerro de los Chenques, Patagônia (44°52’19”S/70°03’57”W), represeta o Manto Litosférico Continental nesta região. Estas rochas guardam registros dos processos a que o manto esteve sujeito durante todo o período de evolução e diferenciação do próprio manto litosférico e de formação de crosta continental. Utilizando-se dados de petrologia, de geoquímica mineral e rocha total de elementos maiores e menores e dados isotópicos, é possível demonstrar que os xenólitos do Cerro de los Chenques possuem paragênese mineralógica primária formada por olivina, enstatita, diopsído e espinélio e que esta paragênese está em equilíbrio, como pode ser observado nos dados de química mineral. Desta forma estas rochas são classificadas como espinélio lherzolitos, espinélio harzburgitos e espinélio olivinawebsteritos, com temperatura e pressão de equilíbrio variando de 782°C a 1029ºC e 14kbar a 19 kbar. Mesmo que a paragênese primária esteja em equilíbrio, ocorrem instabilidades locais com formação de fusão na forma de bolsões de vidro silicáticos e de uma paragênese secundária composta por olivina, diopsídio e espinélio. Os dados geoquímicos de rocha total mostram depleção nos elementos alcalinos e nos elementos traço em relação ao manto primitivo, ilustrando que houve processo de fusão parcial atuando nestas rochas. As amostras estudadas apresentam também feições características de processos de metassomatismo em momentos distintos e guardando características particulares em cada um deles. O primeiro evento metassomático foi determinado como sendo originado por uma pluma de ascenção astenosférica, sendo denotado principalmente pelo enriquecimento nos HFSE (Nb e Ta) e alguns elementos incompatíveis LILE. Este evento é responsável pela metassomatização dos lherzolitos e harzburgitos e pela formação dos olivina-websteritos a partir de um manto granadalherzolítico, onde a granada se torna instável para a formação de clinopiroxênio e espinélio. Eventos metassomáticos posteriores a este também foram identificados, sendo desta vez relacionados a líquidos provenientes da desidratação e fusão de placas oceânicas em zonas de subducção. Um desses eventos está relacionado a colagem dos micro-continentes Maciço Norte Patagônico e Maciço del Deseado, por volta de 350 Ma caracterizado principalmente pelo enriquecimento nos ETR leves em relação aos pesados. O outro, mais recente, relacionado à subducção da Placa Oceânica de Nazca, onde o principal evento é o enriquecimento nos elementos calcófilos (Pb, Sn, W e Sb), que também está registrado em todas as suítes de xenólitos da Patagônia. Foi determinado ainda, que os basaltos de platô de back-arc, resposnsáveis por trazer os xenólitos à superfície não infiltram nos xenólitos, a ponto de alterar a química de suas rochas. / The ultramafic xenolith set from Cerro de los Chenques, Patagônia (44°52’19”S/70°03’57”W), represents the Sub Continetal Lithospheric Mantle (SCLM) of this region. All rocks record processes in the mantle that happened during all period of lithospheric mantle differentiation and crust formation. Using the petrologica data, mineralochemistry, and major, trace and isotope element geochemistry, it is possible to demonstrate that the xenoltihs equilibria mineral assemblage is olivine, enstatite, diopside and spinel. These rocks are classified as spinel lherzolites, spinel harzburgite and spinel olivine websterite, with temperature and pressure equilibrium of 782° to 1029°C and 14 19 kbar, respectively. It is also possible to point out that metassomatic process occurred in the xenolith rocks, which resulted in the crystallization of a secondary assemblage formed by olivine, diopside and spinel, and the formation of silicate melt pockets around spinel and clinopyroxene. Geochemistry data show alkalis and trace elements depletion in relation to primitive mantle as a result of the melting events. The studied samples also show metasomatic events in different periods, with different characteristics. The first metasomatic event was related to an upwelling of an asthenospheric plume, responsible for the HFSE (Nb and Ta) and some incompatible elements (LILE) enrichment in all lithologies, and by the formation of the olivinewebsterite from a garnet-lherzolite, in which garnet reacts out to form clinopyroxene and spinel. Two others metasomatic events must have happened, following this one, both related to fluids and melts originated from the dehydration and melting of the subducting slab. One of these events is related to the collage of the Norte-Patagônia massif to del Deseado massif micro-continets, around 350 Ma, which resulted in the light REE enrichment. The other one, more recent, is related to the Nazca subducting slab, responsible for the enrichment in chalcophile elements (Pb, Sn, W and Sb), which is also observed in all mantle xenoliths from Patagonia. We also discard any infiltration of the host-basalt as the responsible for the ultramafic xenoliths chemical modification.

Made available in DSpace on 2014-06-11T19:32:20Z (GMT). No. of bitstreams: 0 Previous issue date: 2009-03-16Bitstream added on 2014-06-13T19:42:52Z : No. of bitstreams: 1 pede_maz_dr_rcla.pdf: 2841487 bytes, checksum: de1d5493e8e836dce3976583bb30b638 (MD5) / Vazamentos acidentais de derivados de petróleo podem ocorrer em refinarias, dutos, postos de serviços e no transporte rodoviário ou ferroviário, ocasionando diversos impactos ambientais. Este trabalho teve por objetivo avaliar o comportamento de uma pluma de fase livre de querosene, presente em uma área industrial no município de Paulínia (SP), e estudar a recuperação de querosene em resposta à variação sazonal das chuvas. A área de estudo apresentou seis litotipos de origem fluvial, destacando-se a presença de paleocanais preenchidos por areias grossas. Verificou-se que as grandes variações nos níveis d`água proporcionam o fenômeno de trapeamento/destrapeamento do querosene, afetando diretamente o processo de remediação. A área apresenta altas taxas de recarga, variando de 370 mm a 550 mm em um ano. Após 40 meses de remediação, em que se procedeu ao bombeamento de oito poços, foram recuperados 176.000 litros de querosene. O período de maior recuperação foi de outubro a janeiro. Cálculos efetuados a partir dos índices físicos do solo, das propriedades físicas do querosene e da espessura observada de fase livre, em dezembro de 2008, permitiram estimar um volume remanescente recuperável de 192.000 litros de querosene no subsolo / Accidental spills of petroleum products may occur in refineries, pipelines, and service stations, as well as during roadway and railway transportation, causing environmental damages. The main objective of this thesis is to evaluate the behavior of a kerosene free phase plume in an industrial area of the municipality of Paulinia, and evaluate the role of water table fluctuation on hydrocarbon recovery. Six lithofacies deposited in fluvial environment were identified, in particular paleochannels filled by coarse grain sands. An important finding was large water table fluctuation induce entrapment/release of kerosene, greatly affecting aquifer remediation. The studied aquifer underwent high recharge rates of 370 mm to 550 mm per year. Throughout 40 months of remediation, in which eight submersible pumps were employed, 176.000 liters of kerosene were recovered. The largest period of kerosene recovery was in the interval comprising October to January. Calculations using soil physical indexes, physical properties of kerosene and the observed thickness of free phase, as measured in December of 2008, allowed to estimate a volume of 192.000 liters of recoverable remnant kerosene yet in the ground

A suíte de xenólitos ultramáficos do Cerro de los Chenques, Patagônia (44°52’19”S/70°03’57”W), represeta o Manto Litosférico Continental nesta região. Estas rochas guardam registros dos processos a que o manto esteve sujeito durante todo o período de evolução e diferenciação do próprio manto litosférico e de formação de crosta continental. Utilizando-se dados de petrologia, de geoquímica mineral e rocha total de elementos maiores e menores e dados isotópicos, é possível demonstrar que os xenólitos do Cerro de los Chenques possuem paragênese mineralógica primária formada por olivina, enstatita, diopsído e espinélio e que esta paragênese está em equilíbrio, como pode ser observado nos dados de química mineral. Desta forma estas rochas são classificadas como espinélio lherzolitos, espinélio harzburgitos e espinélio olivinawebsteritos, com temperatura e pressão de equilíbrio variando de 782°C a 1029ºC e 14kbar a 19 kbar. Mesmo que a paragênese primária esteja em equilíbrio, ocorrem instabilidades locais com formação de fusão na forma de bolsões de vidro silicáticos e de uma paragênese secundária composta por olivina, diopsídio e espinélio. Os dados geoquímicos de rocha total mostram depleção nos elementos alcalinos e nos elementos traço em relação ao manto primitivo, ilustrando que houve processo de fusão parcial atuando nestas rochas. As amostras estudadas apresentam também feições características de processos de metassomatismo em momentos distintos e guardando características particulares em cada um deles. O primeiro evento metassomático foi determinado como sendo originado por uma pluma de ascenção astenosférica, sendo denotado principalmente pelo enriquecimento nos HFSE (Nb e Ta) e alguns elementos incompatíveis LILE. Este evento é responsável pela metassomatização dos lherzolitos e harzburgitos e pela formação dos olivina-websteritos a partir de um manto granadalherzolítico, onde a granada se torna instável para a formação de clinopiroxênio e espinélio. Eventos metassomáticos posteriores a este também foram identificados, sendo desta vez relacionados a líquidos provenientes da desidratação e fusão de placas oceânicas em zonas de subducção. Um desses eventos está relacionado a colagem dos micro-continentes Maciço Norte Patagônico e Maciço del Deseado, por volta de 350 Ma caracterizado principalmente pelo enriquecimento nos ETR leves em relação aos pesados. O outro, mais recente, relacionado à subducção da Placa Oceânica de Nazca, onde o principal evento é o enriquecimento nos elementos calcófilos (Pb, Sn, W e Sb), que também está registrado em todas as suítes de xenólitos da Patagônia. Foi determinado ainda, que os basaltos de platô de back-arc, resposnsáveis por trazer os xenólitos à superfície não infiltram nos xenólitos, a ponto de alterar a química de suas rochas. / The ultramafic xenolith set from Cerro de los Chenques, Patagônia (44°52’19”S/70°03’57”W), represents the Sub Continetal Lithospheric Mantle (SCLM) of this region. All rocks record processes in the mantle that happened during all period of lithospheric mantle differentiation and crust formation. Using the petrologica data, mineralochemistry, and major, trace and isotope element geochemistry, it is possible to demonstrate that the xenoltihs equilibria mineral assemblage is olivine, enstatite, diopside and spinel. These rocks are classified as spinel lherzolites, spinel harzburgite and spinel olivine websterite, with temperature and pressure equilibrium of 782° to 1029°C and 14 19 kbar, respectively. It is also possible to point out that metassomatic process occurred in the xenolith rocks, which resulted in the crystallization of a secondary assemblage formed by olivine, diopside and spinel, and the formation of silicate melt pockets around spinel and clinopyroxene. Geochemistry data show alkalis and trace elements depletion in relation to primitive mantle as a result of the melting events. The studied samples also show metasomatic events in different periods, with different characteristics. The first metasomatic event was related to an upwelling of an asthenospheric plume, responsible for the HFSE (Nb and Ta) and some incompatible elements (LILE) enrichment in all lithologies, and by the formation of the olivinewebsterite from a garnet-lherzolite, in which garnet reacts out to form clinopyroxene and spinel. Two others metasomatic events must have happened, following this one, both related to fluids and melts originated from the dehydration and melting of the subducting slab. One of these events is related to the collage of the Norte-Patagônia massif to del Deseado massif micro-continets, around 350 Ma, which resulted in the light REE enrichment. The other one, more recent, is related to the Nazca subducting slab, responsible for the enrichment in chalcophile elements (Pb, Sn, W and Sb), which is also observed in all mantle xenoliths from Patagonia. We also discard any infiltration of the host-basalt as the responsible for the ultramafic xenoliths chemical modification.