The Palaeoproterozoic Dannemora inlier is situated in the north-eastern Bergslagen region. The inlier consists of primary and reworked volcanic deposits, stromatolitic limestone and skarn that have been subjected to upper greenschist facies metamorphism. Thicknesses of the different volcanic deposits indicate deposition within a caldera, where syn-volcanic alkali alteration was strong. The deposition was submarine and below wave base in the eastern part of the inlier, but above wave base in the central part where erosion channels together with cross-bedding occurs frequently. The Dannemora Formation is the volcanosedimentary succession of the inlier. Two borehole profiles, a northern and a southern, cover the whole Formation and show different alteration patterns. A strong depletion of Na2O and enrichment of K2O dominate in the southern profile, whereas this pattern is not as evident in the northern profile. The uppermost section of the totally eight constituting the Formation, is intercalated with ore-bearing dolomitic limestone and skarn, and has experienced at least two episodes of alteration. An anticline has been established lithogeochemically from immobile element ratios and the reoccurrence of an accretionary lapilli bed. Numerous altered sub-alkaline, calc-alkaline and basaltic dykes have been recorded in the Dannemora inlier. They are the result of mixing and fractionation of at least three magmatic sources and carry a mixed signature of subduction zone and within-plate volcanic tectonic setting. A seismic profile across the Dannemora inlier images a strong reflector package that dips c. 50° E to the east of the inlier. This package coincides with the polyphase, E-up reverse, brittle-ductile Österbybruk deformation zone (ÖDZ). Yet another steep reflector in the Dannemora ore-field extends to a depth of more than two kilometres. This reflector might represent either a deep-seated iron deposit or a fluid-bearing fault zone.

Orientador: Armando Zaupa Remacre / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-09T03:37:21Z (GMT). No. of bitstreams: 1 Sancevero_SergioSacani_D.pdf: 13993022 bytes, checksum: beb2507aee5ca130897dad57c706b2a9 (MD5) Previous issue date: 2007 / Resumo: O processo de caracterização de reservatórios é atualmente uma das etapas mais importantes na exploração, desenvolvimento e produção de um campo. Porém, para que esse processo seja realizado da melhor forma possível é preciso se ter o conhecimento de determinados métodos, que integram as diferentes informações disponíveis. Desse modo, o objetivo principal dessa tese é estudar de forma criteriosa e quantitativa o processo de caracterização de reservatórios do ponto de vista dos dados sísmicos, avaliando antigos e novos métodos, e definindo novas metodologias que possam ser aplicadas de maneira decisiva neste processo. Para que esses métodos pudessem ser avaliados de maneira conclusiva foi utilizado nesta tese um modelo sintético que reproduzisse minimamente algumas características cruciais de determinados reservatórios como a complexa distribuição dos corpos de areia e a presença de corpos com espessura subsísmica que levassem ao limite as técnicas de modelagem tradicionais, proporcionando avaliar novos métodos. Assim, para caracterizar essas complexas feições, foram utilizados nesta tese dois meios principais de interpretação, primeiro a inversão sísmica dando um caráter preditivo ao dado sísmico e por fim a análise multiatributos, dando um caráter classificatório. No caso da inversão sísmica foram utilizados três métodos de obtenção da impedância acústica. Entre eles, foi a inversão geoestatística que demonstrou ser a mais eficiente das técnicas no que diz respeito à caracterização de reservatórios com espessura subsísmica e complexa distribuição dos corpos de areia. No caso dos atributos, pôde-se demonstrar que é necessário que sejam tratados com uma abordagem multivariada para que seja aproveitada a correlação entre eles e que por meio de técnicas de classificação e modelagem possa se decidir os mais relevantes para o processo. Neste caso 3 métodos de análise multivariada foram apresentados e testados, sendo que dois deles (ICA e MAF) de maneira inédita e que produziram resultados superiores àqueles alcançados quando a tradicional técnica de PCA é aplicada. Assim, com o que foi apresentado, pode-se concluir que o processo de caracterização é um estágio crucial para o desenvolvimento dos campos, mas não é fácil de ser realizado, a menos que os métodos e as técnicas envolvidas sejam conhecidas de maneira profunda. Só assim, é possível extrair o máximo de informações do dado sísmico, caracterizando o reservatório de forma quantitativa e integrada, otimizando sua produção e reduzindo os riscos e custos com a sua explotação / Abstract: The reservoir characterization process can be considered curretly the most important stage in the exploration, development and production of the oil field. However, this process is only carried out in the best way if the geologists, geophisicist and engineering has the knowledge of some definitive methods and techniques that integrated all information available about the field. Thus, the aim of this thesis is to study in a criterious and quantitative way the reservoirscharacterization process, analyzing the seismic data,by the evaluation of classic and novel methods, to defining new methodlogies that can be applied in decisive way into this process. So, for these methods could be evaluated in a conclusive way, were used in this thesis asynthetic reference model that reproduced some critical features of determined reservoirs, as the complex distribution of sand bodies and the subseismic thickness. These characteristics pushing to the limit the traditional modelling techniques. In this thesis to characterizze the complex features present in the reference model we used two interpretation techniques, first we analyze the seismic inversion that give a preditive character to the seismic data and after we study the multiattribute analysis that give a classificatory caracter to the seismic interpretation. For the seismic inversion, the stochastic or geostatistical inversion, that demonstrated to be the most efficient technique to characterized the complex and the subseismic features present in the model. About the seismic attributes it could be demonstrated that even so in some cases they represent the features of the model, are necessary that they are dealt with a multivariate approach, to used the advantage of the correlation between them. For the seismic attribute analysis, 3 methods of multivariate statistics analysis were used, two of them (ICA and MAF) for the first time in the reservoir characterization processo With the results we can proved that these 2 new methods improved the process of multiattribute anlysis prducing superior results when compare with the results obtained by the application of traditional PCA technique. With it was presented, can be concluded that the reservoir characterization process is a crucial stage and have some difficults to be accomplishment, unless the methods and the involved techniques are known deeply. Thus it is possible to extract the maximum informations from the datasets, characterizing the reservoir in a quantitative and integrated environmental, optimizing its production and reducing the risks and the costs with its explotation / Doutorado / Administração e Politica de Recursos Minerais / Doutor em Ciências

Orientador: Martin Tygel / Tese (doutorado) - Universidade Estadual de Campinas, Facudade de Engenharia Mecanica e Instituto de Geociencias / Made available in DSpace on 2018-08-12T05:48:28Z (GMT). No. of bitstreams: 1 UniversidadeEstadualdeCampinas.FaculdadedeEngenhariaMecanica.ProgramadePos-GraduacaoemCienciaseEngenhariadePetroleo_D.pdf: 5963808 bytes, checksum: 11070db7b13faf0139f14fda5d6a4fb6 (MD5) Previous issue date: 2007 / Resumo: O método Common Reflection Surface (CRS) tem por objetivo a obtenção de seções empilhadas de qualidade e extração de parâmetros do campo de onda que caracterizam o meio geológico, através de análises de coerência e com máxima utilização da redundância contida nos dados sísmicos de multicobertura. Para a realização dessas finalidades, o método CRS utiliza "famílias" de pares de fontes e receptores arbitrariamente dispostos em torno de um ponto central e empilhamentos através de tempos de trânsito multi-paramétricos. O CRS representa um significativo aprimoramento do clássico método Common midpoint (CMP), o qual utiliza famílias de pares fonte e receptor simetricamente dispostos em torno do ponto central (denominadas famílias CMP). Além disso, o número maior de parâmetros CRS permite melhores informações sobre o meio geológico. Neste trabalho, discutimos os fundamentos e principais resultados do método CRS na situação 2D, comparando-o ao método CMP. Dentre os vários estudos e aperfeiçoamentos realizados no método CRS, destacam-se (a) nova implementação do programa CRS, com utilização de parâmetros diretamente advindos dos dados; (b) implementação conjunta dos métodos CRS e CMP visando melhor contribuição de cada um deles para o imageamento sísmico; (c) introdução de nova metodologia para eliminação ou tenuação de ruído alinhado nas seções CRS e (d) investigação qualitativa e quantitativa das resoluções vertical e lateral do método CRS. / Abstract: The Common Reflection Surface (CRS) method is designed to produce stacked sections of superior quality, as well as a number of useful wavefield attributes that caracterize the geological subsurface. These attributes are estimated by means of coherency analysis methods, which optimally exploit the redundancy contained in the multicoverge seismic data. To take advantage of this redundancy, the CRS method employs "gathers" of source and receiver pairs, arbitrarily located around a fixed central point, with the help of multi-parametric traveltime moveouts. Waving the restriction of symmetric source-receiver pairs around the central point allows full use of the multicoverage data. As a result, CRS stacked sections are seen to be cleaner, with better signal-tonoise ratio and continuity of reflection events. We discuss the basics and main results of the CRS method, in the 2D situation, in close comparison with the classical CMP method. A number of improvements on the method itself, as well as on its practical applications, are presented. These include (a) a new implementation of CRS, with the use of parameters most directly related to the input data; (b) joint use of CRS and CMP, with the aim of obtaining the best possible processing and imaging results; (c) introduction of a new methodology to eliminate or attenuate aligned noise and (d) qualitative and quantitative investigation on vertical and lateral resolution in CRS sections. / Doutorado / Reservatórios e Gestão / Doutor em Ciências e Engenharia de Petróleo

Iron has been an essential element to human development and iron-oxide deposits are known to host minerals that are labelled as critical raw materials (CRMs), especially in the EU. Therefore, ensuring a sustainable supply of CRMs require access to both primary and secondary sources of their host deposits such as iron oxides. Blötberget is an old mining site in central Sweden rich in both primary and secondary iron-oxide resources (i.e. tailings) from centuries-long mining activities. Thus, this thesis focused on this site, to (1) improve the image of its iron-oxide mineralisation under the historical tailings area through the extraction and processing of 2D data from a wider and sparse 3D dataset, (2) characterise the tailings in terms of geometry delineation and geomechanical property estimation by generating P-wave velocity models of the tailings, and (3) improve the interpretation of existing results in the area through 3D visualisations and comparison. Results from this thesis work suggest possible depth and lateral extensions of the mineralisation for few hundreds of metres beyond what was known previously in the area. It is believed that about 10 Mt of primary iron-oxide resources could arguably be present under the tailing area while the tailings contain an estimated 1 Mt of secondary iron-oxide resources. Also, this thesis work findings indicate that the historical tailings are approximately 10 -12 m thick, 650 m long, and 300 m wide, and has a Vp/Vs ratio between approximately 3-4, indicating a poor geomechanical strength. Additionally, the depth to bedrock in this area was estimated to be 50 m at its deepest parts, with a morphology indicative of complex geological occurrence. Therefore, it is concluded, based on these results, that Blötberget has a good potential to ensure the supply of both iron ore and its constituent CRMs. / Järn har varit ett viktigt grundämne för mänsklig utveckling och järnoxidavlagringar är kända för att innehålla mineral som är märkta som kritiska råmaterial (KRM), särskilt inom EU. Därför kräver säkerställandet av en hållbar tillgång till KRM tillgång till både primära och sekundära källor till deras värdfyndigheter, till exempel järnoxid. Blötberget är en gammal gruvplats i mellersta Sverige som är rik på både primära och sekundära järnoxidresurser (dvs. gruvavfall) från en lång gruvverksamhet. Således fokuserade denna avhandling att (1) förbättra karaktäriseringen av järnoxidmineralisering i det historiska gruvområdet genom utvinning och bearbetning av 2D-data från ett glest 3D-dataset, (2) karakterisering av gruvavfall för avgränsning av geometri och uppskattning av geomekaniska egenskaper genom att generera P-vågshastighetsmodeller för gruvavfallsområdet, och (3) förbättra tolkningen av befintliga resultat i området genom 3D-visualiseringar. Resultat från denna avhandling tyder på möjliga djup och laterala förlängningar av mineraliseringen om några hundratals meter bortom vad som tidigare var känt i området. Det antas att cirka 10 Mt primära järnoxidresurser finnas under avfallssområdet medan gruvavfallet innehåller uppskattningsvis 1 Mt sekundära järnoxidresurser. Dessutom visar denna avhandling att det historiska gruvavfallet är cirka 10-12 m tjockt, 650 m långt och 300 m brett och har ett Vp/Vs -förhållande mellan cirka 3-4, vilket indikerar en låg geomekanisk hållfasthet. Dessutom beräknades djupet till berggrunden i detta område vara 50 m vid dess djupaste delar, med en morfologi som indikerar komplex geologisk förekomst. Därför dras slutsatsen, baserat på dessa resultat, att Blötberget har en god potential att säkerställa leveransen av både järnmalm och dess ingående KRM

Amidst the global climate action movement, geologic carbon storage (GCS) has emerged as a pivotal strategy for mitigating atmospheric CO2 levels, offering environmental and economic opportunities. This thesis targets the Bunter Sandstone Formation within the Rødby structures in Denmark, focusing on seismic Profile 1. Profile 1 is chosen as it crosses over the existing domal structure, and this will enable to investigate the closure or the extension of the domal structure, and also to evaluate its capacity for CO2 sequestration. Utilizing 2D Reflection Seismic Imaging and collaborating with the Geological Survey of Denmark and Greenland (GEUS), the study employs advanced seismic techniques to analyse the Triassic period sandstone formation.  The seismic data for Profile 1 was acquired during June-July 2023 as part of GEUS's national GCS projects by Uppsala University’s Geophysics Program, utilizing the SeisMoveTM dual-element recording system. A total of 991 shots were recorded by 1030 wireless recorders in a fixed geometry, enhancing the signal-to-noise ratio through vertical stacking of repeated shot records. The data acquisition parameters were carefully selected based on similar projects involving pilot and upscaling work conducted in Denmark prior to the Rødby survey. These parameters were influenced by experiences gained during previous successful applications in Denmark and similar environments, ensuring the retrieval of high-resolution seismic reflection images across a wide depth range. The results reveal the presence of a potential new domal structure within the Rødby region, which could substantially influence the area's capacity for carbon storage. The new possible domal structure extend toward east of the survey area and this discovery suggests the need for further investigations to comprehensively assess the extent of this new structure. Therefore, this study enhances the understanding of the Rødby region's subsurface geology; and by advancing the application of carbon capture and storage technologies, this study aligns with Denmark's climate initiatives and contributes to global climate change mitigation efforts. / Mitt i den globala klimatrörelsen har geologisk kollagring (GCS) dykt upp som en viktig strategi för att minska atmosfärens CO2-nivåer, vilket erbjuder miljömässiga och ekonomiska möjligheter. Denna avhandling är inriktad på Bunter-sandstensformationen i Rødby-strukturerna i Danmark, med fokus på seismisk profil 1. Profil 1 valdes eftersom den korsar den befintliga konvexa strukturen, och detta gördet möjligt att undersöka formationens omfattning, och detta i sin tur gör det möjligt att undersöka stängningen eller utvidgningen av domalstrukturen och att utvärdera dess kapacitet för CO2-bindning. Att använda och Isamarbete med Danmarks och Grönlands geologiska undersökning (GEUS) använder studien avancerade seismiska tekniker för att analysera sandstensformationen från triasperioden.  Seismiska data för Profil 1 samlades in under juni-juli 2023 som en del av GEUSs nationella GCSprojekt av Uppsala universitets Geofysikprogram, med hjälp av SeisMoveTM inspelningssystem med dubbla element. Totalt 991 bilder spelades in av 1030 trådlösa inspelare i en bestämd geometri, vilket förbättrade signal-brusförhållandet genom vertikal stapling av upprepade tagningar. Datainsamlingsparametrarna valdes noggrant ut baserat på liknande projekt med pilot- och uppskalningsarbete som genomfördes i Danmark före Rødby-undersökningen. Dessa parametrar valdes baserat på erfarenheter från tidigare framgångsrika tillämpningar i Danmark och liknande miljöer, vilket säkerställde registreringen av högupplösta seismiska reflektionsbilder över ett brett djupområde. Resultaten visar att det finns en potentiell ny struktur i Rødbyregionen, vilket skulle kunna påverka områdets kapacitet för koldioxidlagring avsevärt. Den nya möjliga konvexa strukturen sträcker sig öster om undersökningsområdet och denna upptäckt tyder på behovet av ytterligare undersökningar för att göra en omfattande bedömning av kunna bedöma omfattningen av denna nya struktur. Därför ökar denna studie förståelsen för Rødbyregionens underjordiska geologi. Genom att främja tillämpningen av teknik för avskiljning och lagring av koldioxid är denna studie i linje med Danmarks klimatinitiativ och bidrar till de globala insatserna för att begränsa klimatförändringarna.

Siilinjärvi located in eastern Finland is presently the only phosphate mine with significant phosphorus production in western Europe. Phosphate rock and phosphorus are known as a critical raw material for the European Union due to their economic importance and being prone to the supply risks. Securing their sustainable exploration as well as extraction is hence important. At Siilinjärvi, the phosphate rocks appear within a major Archean alkaline and carbonatite system deformed by several shear zones and intruded by dike systems. By understanding their spatial and temporal relationships an improved exploration and extraction of the ore is possible, which in turn will contribute to the sustainable extraction of this critical material. In October 2018 a novel in-tunnel seismic survey was conducted in the Siilinjärvi open-pit mine. The objective of the study was to employ an in-tunnel seismic survey intersecting several major shear zones running on the eastern side of the main pit, with the idea of characterising its geometry and relationship with the mineralization. The use of the existing mine infrastructure (a water-drainage tunnel) makes the acquisition of the data quite novel in open-pit mines. The water-drainage tunnel nearly in the bottom of the pit crosscutting several major shear zones and dikes was used to enable bench-tunnel seismic data acquisition. High-quality data were acquired using 144 receivers inside the tunnel, with the sources located both inside the tunnel (Bobcat-mounted vertical drophammer) and on the surface (combined explosives and Bobcat-drophammer). Results obtained show at least two reflections interpreted to originate from subvertical shear zones intersecting the tunnel illustrating the importance of such surveys for shear-zone imaging and site characterization. Based on a careful study of a number of shot records, delay in arrival times and partial amplitude lose, these reflections are interpreted to be backscattered surface-waves generated from the shear zones. / Siilinjärvi i östra Finland är just nu den enda fosfatgruvan med en betydande fosforproduktion inom den Europeiska Unionen. Fosfater och fosfor är viktigt för EU på grund av deras ekonomiska betydelse och begränsade tillgång. Den fosforbärande bergarten i Siilinjärvi befinner sig i ett stort Arkeiskt alkalisk och karbonatit-komplex som är deformerad av flera skjuvzoner och intruderat gångsystem. En förbättring av sökandet och utvinnandet av denna viktiga malm skulle vara möjligt genom en ökad förståelse för de spatiala och temporala relationerna i komplexet. Syftet med denna studie var att tillämpa en ny seismisk undersökning, baserad på existerande infrastruktur i gruvan, för en bättre geologisk förståelse och därmed en förbättrad exploatering. En innovativ seismisk undersökning av tunnlar gjordes i Siilinjärvis dagbrott oktober 2018. En vattendräneringstunnel nästan i botten av brottet som korsar fem skjuvzoner användes för att mäta seismiskt tunnel-data. Hög kvalitativ data samlades in genom att använda 144 mottagare inuti tunneln med källor lokaliserade både inuti tunneln, i form av en vertikal dropphammare monterad på en Bobcat, och på ytan i form av en kombination av sprängning och Bobcatmoterad dropphammare. Två reflektioner tolkades att ha sitt ursprung från subvertikala skjuvzoner som korsar tunneln vilket visar på vikten av dessa typer av undersökningar för skjuvzons detektion och områdes karaktärisering.

Orientadores: Denis Jose Schiozer, Celio Maschio / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica, Instituto de Geociencias / Made available in DSpace on 2018-08-14T07:27:37Z (GMT). No. of bitstreams: 1 Ida_Mauro_M.pdf: 14939670 bytes, checksum: 3bac33f4177c36ec35c53933f345273b (MD5) Previous issue date: 2009 / Resumo: Boas decisões no gerenciamento de um campo de petróleo em produção dependem fortemente da confiabilidade da previsão de produção que demanda um modelo de escoamento que reproduza com boa precisão o histórico de produção. Devido à complexidade do processo de ajuste de histórico de produção, vários modelos podem resultar em ajustes aceitáveis, porém ainda com incertezas na previsão de produção, principalmente pelo fato de existirem algumas heterogeneidades de grande impacto não observadas na fase de caracterização do modelo. Para reduzir as incertezas, surgiu a tecnologia de sísmica 4D que a partir de análises qualitativas permite identificar frentes de saturação de água, resultando em grandes avanços na caracterização do reservatório e, conseqüentemente, no ajuste de histórico. Apesar de muito útil, em alguns casos podem levar a interpretações equivocadas, sendo necessário um procedimento adicional para o uso da informação dessa tecnologia. O objetivo principal deste trabalho é propor uma metodologia que utiliza simultaneamente os dados de produção e quantitativamente a impedância acústica da sísmica 4D para identificar as heterogeneidades do reservatório visando melhorar a qualidade do ajuste de histórico. A metodologia proposta consiste de duas etapas principais: parametrização e otimização com algoritmo genético. A validação da metodologia proposta foi realizada num modelo bidimensional five-spot com duas falhas geológicas e um canal de alta permeabilidade e a aplicação foi realizada num modelo modificado do Campo de Namorado com as seguintes características: total de 44 poços, uma falha geológica e um canal de alta permeabilidade. Em todos os modelos, foram constatados ganhos de qualidade no ajuste de histórico proporcionado pela incorporação quantitativa da sísmica 4D. / Abstract: Good decision making related to oilfield management depends on reliability of production forecast which demands calibrated reservoir simulation models. Due to the complexity of the production history matching process, there are many models with reasonable match but, many times, with different forecasts, mainly due to important heterogeneities that are not observed during the reservoir characterization phase. In order to reduce this uncertainty, a new technology named 4D seismic became available which uses quantitative analysis to identify water saturation front resulting in huge advance in reservoir characterization and consequently in history matching. Although this technology is very useful, in some cases, it can result in mistaken interpretation and it needs additional work to use this technology. The main objective of this work is to propose a methodology to use production data and quantitatively acoustic impedance from 4D seismic to identify reservoir heterogeneities to increase the quality of the history matching. The methodology proposed is divided in two main steps: parametrization and optimization with genetic algorithm. The validation of methodology proposed was done in a simple synthetic model and the application was done in the Namorado Field, modified with one geological fault and one channel with high permeability. / Mestrado / Reservatórios e Gestão / Mestre em Ciências e Engenharia de Petróleo

Dans les zones de subduction, la géométrie du slab est l'un des paramètres qui contrôle les déformations tectoniques de la marge, le couplage et le potentiel sismogénique. La subduction des Antilles résulte du chevauchement de la plaque Caraïbe vers le NE sur les plaques Amériques, à une vitesse de convergence de 2 cm/an. La sismicité est hétérogène et augmente localement sous la plateforme des Iles Vierges. D’une obliquité croissante vers le nord, cette zone est favorable à un partitionnement dont les déformations sont très peu observées. Ces travaux ont permis de confirmer un substratum d’une affinité de croûte océanique épaissie par un panache mantellique et faiblement épaissi par le magmatisme formant les arcs volcaniques Deux structures accommodant le partitionnement de la déformation ont été mis en évidence. La faille de Bunce est une faille décrochante sénestre de 850 km s’étendant d’Hispaniola jusqu’à Barbuda découplant le prisme d’accrétion du substratum. Le Passage d’Anegada, dont nous avons découvert son extension vers le NE, entaille profondément l’avant-arc. Formé par extension due à la collision du Banc des Bahamas sur le nord de la marge caribéenne, ces structures sont réactivées en décrochement sénestre compatible avec du partitionnement. Les caractéristiques d’une dorsale lente (core complexe et grain océanique) entrant en subduction sont imagées pour la première fois. Elles affectent probablement la morphologie du prisme d’accrétion et le potentiel sismogène. Là où les séismes et les déformations de partitionnement (Passage d’Anegada) s'accentuent localement, le slab est moins profond. Ainsi, le couplage interplaque pourrait augmenter localement et favoriser l'activité sismique et le partitionnement tectonique sous le Passage d'Anegada. / In subduction zones, the 3D geometry of the plate interface is one of the key parameters that controls margin tectonic deformation, interplate coupling and seismogenic behavior. The North American plate subducts below the Caribbean plate with a convergence rate of 20 mm/y. The seismic activity is heterogeneous and increases locally under the Virgin Islands platform. The northward increasing convergence obliquity is favorable in partitioning which deformations were not really observed. This PhD confirms that the forearc crust is a crust of oceanic affinity thickened by hotspot magmatism and poorly affected by subduction magmatism. Two structures accommodating the partitioning of the deformation were identified. The Bunce Fault is a 850-kmlength sinistral strike-slip fault extending from Hispaniola to the east of Barbuda decoupling the accretionary prism from the Caribbean substratum. The Anegada Passage, whose extension towards the NE is highlighted, entailed deeply the forearc. The structures are reactivated in sinistral strike-slip faults compatible with the partitioning of the deformation after formation in extension due to the collision of the Bahamas Bank with the northern margin. We image for the first time the characteristics of a slow ridge formation (partly complex core and partly oceanic grain) entering in subduction. It affects the morphology of the accretion prism and probably the seismogenic potential of the subduction interface. We have highlighted a shallower slab which is located under the NE Anegada Passage and where earthquakes and partitioning deformations increase locally. Thus, the shallowing slab might results in a local greater interplate coupling favoring seismic activity and tectonic partitioning beneath the Anegada Passage.

Sedimentary processes are critical geological phenomena in the evolution of continental margins. Environmental forces from various temporal and spatial scales control these processes. Due to the fast increase of anthropogenic activities in marine environments, these studies on sedimentary processes and their products are becoming increasingly necessary. In this context, geophysical data, such as high-resolution 2D seismic reflection profiles, are efficient tools to characterize sedimentary processes and deposits. This study aimed to map and interpret different types of echo character on the continental shelf of the São Paulo Bight to increase the knowledge of the spatial variability of sedimentary processes in current-dominated shelf settings. With this aim, 120 seismic lines, almost 3200 km in length, have been analyzed in conjunction with 451 surficial sediment samples. Based on the broad-scale seafloor morphology, microtopography and seismic characteristics (e.g., sharpness, amplitude, continuity) of sub-bottom reflections, seven echo types distributed in three echo classes were identified in the study area. Type 1-1 is a flat seafloor with either no or low-amplitude sub-bottom reflectors, mainly observed in the middle shelf; type 1-2 is a flat sea floor with medium to high-amplitude sub-bottom reflectors also found in middle shelf settings; type 1-3 is defined by a transparent acoustic response below the seafloor evolving downsection into a highly reflective pattern that covers most of the inner shelf; type 1-4 presents a flat seafloor molded by regularly spaced undulations, and it is restricted to the outer shelf; type 2-1 consists of mounds with no internal reflectors also located on the outer shelf; type 3-1 is an irregular echo with prolonged internal reflectors found around the São Sebastião Island; finally, type 3-2 is a broad irregular echo with high relief variations mainly found in the outer shelf. The analysis of the seismic survey allowed recognizing that the distribution of the echoes reflects not only the composition of the seabed but also the sedimentary processes that acted during the deposition of the material. In the inner shelf and middle shelves, the Brazilian Coastal Current and the action of waves are the main processes responsible for the echo types found, while the outer shelf echo types are strongly influenced by the Brazil Current. / Processos sedimentares são fenômenos importantes na evolução das margens continentais. Esses processos são controlados por forçantes de várias escalas espaciais e temporais. Devido ao rápido crescimento das atividades antropogênicas em ambientes marinhos, estudos sobre processos sedimentares e seus produtos tem se tornado cada vez mais necessários. Nesse contexto, dados geofísicos, como perfis de sísmica de reflexão de alta resolução, são ferramentas importantes na caracterização desses processos e depósitos. O objetivo do estudo foi mapear e interpretar os tipos de caráter de eco na plataforma continental do estado de São Paulo visando aumentar o conhecimento a respeito da variabilidade espacial dos processos sedimentares em plataformas dominadas por correntes. Para alcançar esse objetivo 120 linhas sísmicas totalizando quase 3200 km em extensão foram analisadas em conjunto com 451 amostras sedimentares. Baseados na morfologia de macro e microescala e características sísmicas do sinal acústico de fundo como nitidez, amplitude e continuidade dos refletores, foram identificados 7 tipos de caráter de eco distribuídos em 3 classes (fundo plano, monticular ou irregular). O tipo 1-1 apresenta fundo plano com refletores de sub fundo ausentes ou de baixa amplitude localizado principalmente na plataforma média; o tipo 1-2 refere-se a um fundo plano com refletores internos com amplitudes médias a altas também presente na plataforma média; o tipo 1-3 é definido por uma camada superficial transparente que é substituída em profundidade por uma camada altamente refletiva que cobre grande parte da plataforma interna; o eco 1-4 apresenta fundo moldado por ondulações com localização restrita na plataforma externa; o tipo 2-1 consiste em montes sem refletores internos localizado próximo a quebra da plataforma; o tipo 3-1 é irregular com refletores internos prolongados e é encontrado ao sul da Ilha de São Sebastião; finalmente, o eco 3-2 é um eco irregular que apresenta grandes variações de relevo presente em grande parte da plataforma externa. A análise dos dados sísmicos permitiu o reconhecimento de que os ecos respondem não somente a composição sedimentar superficial, mas também os processos sedimentares que atuaram durante a deposição do material. Nas plataformas interna e média, a Corrente Costeira Brasileira e a ação de ondas geradas pelos ventos são os principais processos responsáveis pela geração dos ecos encontrados, enquanto na plataforma externa, os tipos de eco são fortemente influenciados pela Corrente do Brasil.

Neste trabalho avaliou-se a potencialidade do uso da sísmica rasa de reflexão multicomponente para investigação geológica-geotécnica. Foram abordados vários aspectos relacionados à aquisição dos dados sísmicos de reflexão multicomponente, com o objetivo de entender as vantagens e limitações do método para aplicação em investigações de subsuperfície rasa. Os ensaios de campo foram realizados em duas áreas, ambas em terrenos da Bacia Sedimentar de São Paulo, em área urbana da cidade de São Paulo. Para a interpretação dos dados sísmicos multicomponente foram investigados procedimentos para a inversão não-linear dos tempos de trânsito e das amplitudes. O testes realizados orientaram a escolha da aproximação não-hiperbólica mais apropriada para calculo dos tempos de trânsito visando à análise de velocidades do pacote acima do refletor. O estudo numérico desenvolvido para a inversão das amplitudes mostrou a viabilidade da estimativa das velocidades e densidades, acima e abaixo do refletor, empregando-se as equações de Zoeppritz para as ondas refletidas PP, PSv, SvP e SvSv, antes e depois do ângulo crítico. Dada a complexidade da inversão nao-linear das amplitudes, se fez necessário elaborar uma estratégia estocástica de otimização e desenvolver uma nova abordagem para análise da função objetivo multi-dimensional, garantindo confiabilidade ao resultado da inversão não-linear. Os resultados deste trabalho mostraram o potencial da sísmica de reflexão rasa multicomponente para caracterização geológica-geotécnica, possibilitando um melhor entendimento das camadas superficiais. / This thesis aims to evaluate the useful of the multicomponent seismic methods for shallow investigations, mainly its potential for the geotechnical and geological characterization of the nearsurface. Several aspects regarding the acquisition and processing data of multicomponent seismic data are discussed. They were based on data set acquired in the urban area of Sao Paulo city, Brazil. Two different areas were investigated. Both located in sedimentary terrains belonging to the Sao Paulo Sedimentary Basin. We present a non-linear travel time and seismic amplitude inversion scheme to quantitative interpretation of multicomponent seismic data. Several tests were performed to guide the choice of non-hyperbolic equation more suitable for travel time inversion aiming the velocity analysis above the reflector. A numerical experiment developed to solve the nonlinear inversion of seismic amplitudes showed the feasibility to estimate seismic interval velocities and layer densities above and below the reflector using the exact Zoeppritz equations for PP, PSv, SvP e SvSv reflected waves, before and after critical angle. Due to the apparent complexity of the nonlinear seismic amplitude inversion, it was necessary elaborate the strategy for stochastic optimization and develop a new approach to analyze the multi-dimensional objective function, with different implications for the accuracy and efficiency of the non-linear inversion. The study show the benefits of using the multicomponent seismic method for shallow geological-geotechnical characterization, improving the nearsurface understanding, once allows an integrated analyzes of a more complete record of the wave field.