Spelling suggestions: "subject:"geophysical - data processing""
1 |
Improving the quality control of marine geophysical trackline dataChandler, Michael T January 2006 (has links)
Thesis (M.S.)--University of Hawaii at Manoa, 2006. / Includes bibliographical references (leaves 97-98). / viii, 98 leaves, bound ill. 29 cm
|
2 |
Applications of prolate spheroidal function theory to geophysical data processingRodríguez, José Antonio January 1987 (has links)
Because signals that are simultaneously concentrated in time and frequency are common in geophysics, it is desirable to develop a set of basis functions with these properties to perform various types of data processing. The Prolate Spheroidal Functions (PSF's) form a complete orthonormal set, and the low-order PSF's span the space of functions which are simultaneously concentrated in time and frequency. In this study, the PSF's are utilized in three different data processing problems: spectrum estimation, signal-to-noise ratio enhancement, and wavelet estimation. All three problems are related by functions which are approximately time- and bandlimited: data tapers for spectrum estimates,
time- and bandlimited signals, and seismic wavelets can all be expressed as linear combinations of the low-order PSF's.
Some of the results obtained by applying the PSF's to solving these problems are encouraging.
In the problems of spectrum estimation and wavelet estimation in particular, the PSF's seem to extract much of the information present in the data. The application of PSF's to solving problems in geophysical data procesing should be the focus of further research in the future. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate
|
3 |
An inexpensive system of geophysical data acquisitionMomayezzadeh, Mohammed January 1987 (has links)
Note:
|
4 |
Analysis of potential field gradient tensor data : forward modelling, inversion and near - surface explorationHeath, Philip John January 2007 (has links)
In this thesis the mathematics of the potential field gradient tensor is thoroughly reviewed and the inter - relationships between the various components and quantities are established. Numerical forward modelling of 3D regolith scenarios is undertaken, showing that current instrumentation for measuring magnetic gradients is useful for near - surface exploration. Gravity gradiometry is only able to detect relatively large contrasts in density, and does not offer the same small - scale resolution as magnetic gradiometry. I examine the magnetic case further by incorporating surface measurements of magnetic susceptibility. These data are highly variable, and forward modelling shows while gradiometry is useful for regolith exploration, interpretation is difficult due to the high level of geological noise. I have tested new and standard filters as tools for extracting information from gradient tensor data. This includes boundaries between geological units and possible mineralisation positions. New techniques developed involve calculating an Analytic Signal for the entire gradient tensor, and forming multiplicative combinations of the individual gradient tensor components. The determinant and inverse of the gradient tensor 3 x 3 matrix can also yield useful information pertaining to source position and geological boundaries. These are illustrated by means of synthetic data examples. Examination of inversion techniques on gradient tensor data illustrates that single component inversion is comparable in the quality of the final result to a multi - component inversion, albeit much faster. Eigenvalues and eigenvectors of the full tensor produce information about depth and direction, although interpretation must be taken with care. I have developed an inversion routine to locate magnetic dipole sources, and illustrate how it produces multiple solutions to a problem, and how it is not possible to unambiguously determine which of these is correct. A new inversion routine was therefore developed. This new hybrid global inversion routine is an automated technique to locate a generalised magnetic multipole. It can locate dipole and quadrupole ( and some octupole ) sources successfully, and be used either in real time as data is being collected, or as post - processing on an entire data set. / Philip Heath / Thesis (Ph.D.)--School of Chemistry and Physics, 2007.
|
5 |
The development of two-dimensional digital operators for the filtering of potential field data.Parsneau, Harold Paul. January 1970 (has links)
No description available.
|
6 |
The development of two-dimensional digital operators for the filtering of potential field data.Parsneau, Harold Paul. January 1970 (has links)
No description available.
|
7 |
Integração de dados aerogeofisicos e geologicos e sua contribuição a evolução geodinamica do dominio Ceará Central, Provincia Borborema / Airbone geophysical and geologic data integration and its contribution the geodynamic evolution of central Ceara domain, Borborema ProvinceAmaral, Wagner da Silva, 1979- 23 March 2007 (has links)
Orientador: Ticiano Jose Saraiva dos Santos / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-09T21:14:51Z (GMT). No. of bitstreams: 1
Amaral_WagnerdaSilva_M.pdf: 44117000 bytes, checksum: fc74c3c06d9f515fb8c5571bbc187c3b (MD5)
Previous issue date: 2007 / Resumo: O avanço das tecnologias de processamento de dados aerogeofísicos e integração com dados geológicos permitem recuperar informações úteis e valiosas contidas em levantamentos geofísicos com uma tecnologia mais antiga. Essas informações representam uma ferramenta essencial ao mapeamento geológico-estrutural de terrenos Pré-Cambrianos, onde as relações estratigráficas e estruturais são difíceis de serem delineadas em trabalhos de campo. Dados aerogeofísicos adquiridos nos Projetos Rio Acaraú (1975) e Itatira (1977), realizados respectivamente nas regiões noroeste e central do Ceará, foram processados e integrados com a finalidade de gerar produtos que possam ser utilizados como ferramenta indireta na identificação de feições geológicas regionais. A verificação e aplicabilidade do método foram postas em prática com a definição de uma área piloto compreendida pelas folhas topográfica 1.100.000 Umirim e Canindé. A integração dos dados aerogeofísicos e geológicos de campo, dando suporte ao mapeamento geológico em escala 1:100.000, permitiu reconhecer duas principais unidades de mapeamento: o Arco Magmático de Santa Quitéria ¿ AMSQ e as seqüências supracrustais para e ortoderivadas que o bordejam. Do arco, foram identificados quatro tipos litológicos representados por Np1: Núcleos anatéticos; Np2: Migmatitos ortoderivados; Np3: Granitos gnáissicos porfiríticos; Np4: Gnaisses granodioríticos. Da supracrustal têm-se: a seqüência paraderivada (Ccp) constituída por seis subunidades de mapeamento, onde se destacam paragnaisses, migmatitos, micaxistos, quartzitos, cálcio silicáticas e metacalcários; e a seqüência ortoderivada (Cco) formada por oito subunidades compostas por granodioritos, leucogranitóides, migmatitos (diatexitos e metatexitos), anfibolitos, dioritos e granulitos máficos. A análise dos lineamentos estruturais da área de estudo, foi realizada com o processamento e interpretação dos produtos aeromagnéticos e do modelo digital do terreno-SRTM para a extração das grandes estruturas regionais. Os maiores lineamentos da região correspondem a zonas de cisalhamentos transcorrentes destrais representadas pelo do sistema de falhas de Paramoti (ZCP) de direção NE-SW, e as zonas de cisalhamento de baixo ângulo com vergência para E-SE no setor noroeste, e para W-NW no setor sudeste. Em termos deformacionais, o principal regime atuante na área é de natureza compressiva, responsável pela geração de foliações, lineações, dobras e zonas de cisalhamento, contendo três fases deformacionais denominadas Fn, Fn+1, Fn+2. A fase Fn é representada por empurrões com vergência aproximada para E-SE no setor NW e para W-NW no setor SE. A fase Fn+1, de natureza transpressional, marca o desenvolvimento de zonas de cisalhamento de direção aproximada NE-SW. E por fim, a fase Fn+2 relaciona-se à exumação e conseqüente tectônica frágil das rochas supracrustais. As rochas do arco magmático de Santa Quitéria foram caracterizadas por apresentarem altas contagens no canal de K em quase toda região de abrangência e contagens intermediárias e baixas de Th e U. De modo geral, a seqüência supracrustal foi caracterizada por apresentar alta contribuição dos canais de U e Th e baixa de K. As subunidades Migmatitos anfibolíticos e Metaultramáficas (Cco3) e Hornblenda gnaisses migmatíticos, granulitos máficos (Cco4), compostas por rochas máficas/metaultramáficas e anfibolíticas, onde se destaca a ocorrência faixas de retro-eclogitos e granulitos máficos encaixados como lentes em gnaisses e migmatitos apresentam fortes anomalias negativas, com baixas contagens nos três canais K-Th-U. A anomalia mais proeminente com esses registros encontra-se na região central da área, a sul do município de Pentecoste. Na magnetometria essas rochas têm anomalias positivas com altos valores de susceptibilidade magnética / Abstract: Advances in airborne geophysical data processing techniques and their integration with geologic data allow recovering valuable information from both geophysical surveys and, the older technology. These information represent an essential tool for geologic-structural mapping of Pre-Cambrian terrains, where the stratigraphic and structural relations are difficult to be delineated in field works. The airborne geophysical data from Rio Acaraú (1975) and Itatira (1977) projects were carried out through respectively, in the northwest and central regions of the State of the Ceará. Their processing produced products useful to indirectly identify regional geologic features. The verification and applicability of this approach was tested in an pilot-area whose limits are within the Umirim and Canindé topographic sheets, at 1: 100,000 scale. The integration between the airborne geophysical and the geologic field data supported to the geologic mapping at the same cited scale. Two main units were recognized: the Santa Quitéria Magmatic Arc - AMSQ and the para-and-orthoderivative supracrustal sequences that surround the arc. The AMSQ has four major lithologies: Np1 with anatetic granites; Np2: orthoderivated migmatites; Np3: porfiritic gneissic granites; Np4: granodioritic gneisses. The paraderivative supracrustal sequence (Ccp) consists of six mapped subunits, the paragneisses, marbles migmatites, mica-schists, quartzites and, calk-silicated rocks. The ortoderivative sequence (Cco) is formed by eight subunits, the granodiorites, leucogranitoids, mafic migmatites (diatexites and, metatexites), amphibolites, diorites and, granulites. The structural lineaments analysis at regional scale was done after the processing and interpretation of the airborne magnetic products and, the digital elevation model derived from the Shuttle Radar Topographic Mission-SRTM. The major lineaments correspond to the dextral transcurrent Paramoti Shear Zone (ZCP) of NE-SW direction and, to low angle shear zones with E-SE thrustdirection at the Northwestern sector and, another shear zone facing to W-NW direction at the Southeastern sector. About the deformation history, the main operating regime was compressive and, responsible for foliation, lineation, folds and shear zones.This history comprises three deformational phases called Fn, Fn+1, Fn+2. The Fn phase is represented by thrust toward E-SE in the Northwestern sector and towards W-NW direction at the Southeastern sector. The Fn+1 phase, of transpressional nature, marks the development of shear zones with NE-SW direction. Finally, the Fn+2 phase is related to the exhumation and consequently ruptile tectonics of the supracrustal rocks. The rocks from Santa Quitéria magmatic arc are characterized by high counting on the K-channel in its almost entire region and intermediate and low counting of Th and U. Generally, the supracrustal sequences are characterized by high values on the U-and-Th-channels and low on K-channel. The subunit Metaultramafics (Cco3) and Hornblendgnaisses and, mafics granulites (Cco4), are remarkable by the occurrence retro-eclogites bands and mafic granulites as lenses within gneisses and migmatites. These subunits present strong negative anomalies, with low counting on the three K, Th and, U channels. The best example for this negative anomalies are in the central region of the area, at south of Pentecostes city. That area also has positive magnetic anomalies, with high values of magnetic susceptibility / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências
|
8 |
Dados aerogeofisicos e geologicos aplicados a seleção de areas favoraveis para agua subterranea no dominio cristalino do Ceara, Brasil / Airborne geophysical and geological data applied to the selection of groudwater potential areas in crystalline rocks of Ceara, BrazilSouza Filho, Oderson Antonio de 12 August 2018 (has links)
Orientadores: Adalene Moreira Silva, Monica Mazzini Perrota, Anne Elizabeth McCafferty / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-12T07:51:08Z (GMT). No. of bitstreams: 1
SouzaFilho_OdersonAntoniode_D.pdf: 17063311 bytes, checksum: 23989ebe7eca5130b41af0d5296d42a9 (MD5)
Previous issue date: 2008 / Resumo: Os métodos usuais de locação de poços tubulares para água subterrânea no Nordeste do Brasil baseiam-se na identificação de estruturas permissivas através de fotointerpretações e caminhamentos geofísicos eletromagnéticos indutivos e eletrorresistivos em áreas de pouca extensão. Os resultados alcançados por esses métodos mostram uma grande variabilidade na produtividade de poços. Esta tese privilegia a utilização das geotecnologias, notadamente os levantamentos aerogeofísicos e modelagens espaciais para mapear regiões favoráveis para água subterrânea e a sua qualidade numa área do Estado do Ceará, Brasil. O conjunto de dados compreende levantamento aerogeofísico local e regional, imagens do sensor multiespectral ETM+/Landsat-7 e dados de campo. O desenvolvimento da tese teve três etapas: o processamento dos dados aerogeofísicos magnéticos, eletromagnéticos e radiométricos; a abordagem geoestatística objetivando o zoneamento da condutividade elétrica da água subterrânea e; a modelagem de propriedades geofísicas associadas a poços de alta e baixa vazão. O processamento aerogeofísico realçou estruturas compatíveis com a pesquisa hídrica até 250 m de profundidade. Gradientes magnéticos anômalos lineares e rasos, porém contínuos abaixo de 400 m, foram diferenciados das anomalias superficiais através da integração entre os aerolevantamentos. Inversões dos dados eletromagnéticos indicam que a camada de solo é bastante condutiva e o substrato rochoso é resistivo após 15 m deprofundidade, dificultando a detecção de estruturas mais profundas. As técnicas de krigagem e simulação estocástica foram aplicadas às medidas de condutividade elétrica nos poços tubulares (variável principal) e aos dados aerogeofísicos de condutividade elétrica aparente do solo (variável externa) para gerar um mapa de condutividade elétrica da água subterrânea. A informação aerogeofísica de alta resolução auxiliou na simulação da variabilidade da condutividade elétrica da água. Testes de validação comparando valores calculados com medidas em novos poços confirmaram a competência destes modelos em caracterizar a qualidade das águas subterrâneas em rochas cristalinas. As técnicas de análise espacial por razão de probabilidades e pesos de evidências compararam valores de cada propriedade geofísica, lineamentos estruturais e dados multiespectrais a poços de diferentes vazões. Os modelos obtidos mostram que os poços mais produtivos estão associados ao substrato rochoso não-magnético, eletricamente condutivo, cortado por gradientes não-magnéticos WNW-ESE, lineamentos estruturais e por gradientes condutivos N-S. Dados de campo comprovaram a natureza rúptil extensional das estruturas WNW-ESE e N-S. As propriedades do solo, interpretadas através de dados radiométricos (teor de potássio maior do que urânio) e dos dados multiespectrais (conteúdo relativo de minerais de óxido de ferro e argilo-minerais) indicam uma associação de poços mais produtivos com solos de fração grosseira predominando sobre a componente mais fina e os argilo-minerais prevalecem como produtos de alteração em relação aos minerais de óxido de ferro. / Abstract: The location of water well in Northeast Brazil is usually based on the interpretation of structural lineaments in aerial-photographs and electromagnetic and electrical resistivity ground geophysics surveys. However, the success of these techniques is variable, and the small coverage area is another limitation. This Thesis favors a different approach, the use of airborne geophysical surveys and spatial modeling to map groundwater potential and quality in the State of Ceará, Brazil. The data sets comprise a local helicopter survey, a regional airborne survey as well as multispectral images from the Enhanced thematic Mapper sensor (ETM+)/Landsat-7 and field data. The thesis was developed in three stages: i) the processing of airborne magnetic, electromagnetic and radiometric data; ii) a geostatistical modeling to produce groundwater electrical conductivity maps, and; iii) groundwater favorability modeling based on the association of high- and low-yield wells and geophysical, structural and spectral properties. The magnetic anomaly data were filtered using the regional and local survey to enhance through-going structures whose gradients crosscut rocks below 400 m depth. The helicopter electromagnetic data (HEM) were processed so that shallow (up to 15 m depth) conductive structures and lithologic units were enhanced. Inversion modeling applied to electromagnetic data unveiled a conductive soil horizon over a resistive bedrock at depths greater than 15 m which restricts the detection of deeper conductive anomalies. The regional radiometric data together with ETM+ images characterized the soil texture and relative contents of Fe-oxide/clay-mineral/vegetation density ratios. Structural data were interpreted from aerialphotographs and from ETM+/Landsat-7 data. Kriging and stochastic simulation techniques were applied to electrical conductivity data from water-wells to generate a groundwater electrical conductivity map. The HEM data were used as an external variable to characterize the variability of groundwater electrical conductivity associated with crystalline aquifers. Validation tests comparing predicted values with measurements in new wells confirmed the competence of these models in locating fresh groundwater sources in bedrock. The probability ratio and weights of evidence techniques quantitatively described the association of each value of magnetization, electrical conductivity, geophysical gradients, structural lineaments, radiometric data and multiespectral data to different well yields. The groundwater favorability models imply the existence of structural lineaments in an E-W direction, with non-magnetic properties, which are pervasive below 250 m depth but conductive from up to 15 m below the surface. The E-W lineaments are cut by conductive N-S structures. Field data confirm that the geophysical trends are extensional brittle structures. High yield classes are more associated with coarse-grained soils (high potassium, medium thorium and uranium) where alteration minerals are predominantly clay-minerals as opposed to Fe-oxide minerals. / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências
|
9 |
The implementation of a core architecture for geophysical data acquisitionHeasman, Ray Edward January 2000 (has links)
This thesis describes the design, development and implementation of the core hardware and software of a modular data acquisition system for geophysical data collection. The primary application for this system is the acquisition and realtime processing of seismic data captured in mines. This system will be used by a commercial supplier of seismic instrumentation, ISS International, as a base architecture for the development of future products. The hardware and software has been designed to be extendable and support distributed processing. The IEEE-1394 High Performance Serial Bus is used to communicate with other CPU modules or peripherals. The software includes a pre-emptive multitasking microkernel, an asynchronous mailbox-based message passing communications system, and a functional IEEE-1394 protocol stack. The reasons for the end design and implementation decisions are given, and the problems encountered in the development of this system are described. A critical assessment of the match between the requirements for the project and the functionality of the implementation is made.
|
10 |
Modelagem espacial de dados aerogeofísicos e interpretação de imagens SAR aplicados ao mapeamento geológico e metalogenético da região central do Domínio Bacajá, Estado do Pará / Spatial modeling of aerogeophysical data and interpretation of SAR images with application to geological and metallogenetic mapping of the central Bacajá Domain, State of Pará, BrazilCarneiro, Cleyton de Carvalho 08 June 2010 (has links)
Orientadores: Álvaro Penteado Crósta, Adalene Moreira Silva, Carlos Eduardo de Mesquita Barros / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-17T01:56:29Z (GMT). No. of bitstreams: 1
Carneiro_CleytondeCarvalho_D.pdf: 23993217 bytes, checksum: bae5d88ad6f1ac50ca114b9b7acc5a8f (MD5)
Previous issue date: 2010 / Resumo: O Domínio Bacajá está localizado na parte leste do Cráton Amazônico, no âmbito da Província Maroni-Itacaúnas ou Transamazonas, de idade paleoproterozóica. A interpretação vigente dos limites entre as unidades litoestratigráficas que compõem o Domínio Bacajá foi baseada, sobretudo, em dados aerogeofísicos adquiridos na década de 1970. Entre 2004 e 2005 foram realizados aerolevantamentos de radar (SAR) pelo Sistema de Proteção da Amazônia (SIPAM) e geofísicos (magnetometria e gamaespectrometria) foram adquiridos pelo Serviço Geológico do Brasil (CPRM). Os novos dados são de fundamental importância ao desenvolvimento de pesquisas visando o avanço do conhecimento geológico e do potencial mineral da região. Esses dados foram analisados e modelados espacialmente para geração de mapas geológicos e de informações sobre o potencial aurífero da região central do Domínio Bacajá. Os resultados obtidos sugerem que o limite entre o Domínio Bacajá e a Província Carajás estaria situado entre as unidades Ortognaisse Pacajá (Neoarqueano) e Granulito Novolândia (Riaciano). A modelagem a partir da técnica fuzzy indicou zonas favoráveis à ocorrência de rochas máficas e ultramáficas, que incluem anfibolitos, diabásios, gabros e metagabros. Com a modelagem a partir da técnica Self-organizing maps (SOM), foram definidas classes relacionadas às principais variedades litológicas que ocorrem nessa região do Domínio Bacajá. Ocorrências auríferas encontram-se associadas às zonas cujas assinaturas gamaespectrométricas indicam alto teor potássico, marcadas ainda por lineamentos de direção NW-SE. Tais características sugerem a presença de estruturas extensionais associadas às zonas de cisalhamento na região onde ocorrem as rochas máficas da Sequência Três Palmeiras. A partir desses resultados, é apresentada uma nova proposta de distribuição das principais unidades litoestratigráficas em escala de 1:100.000 para a região central do Domínio Bacajá / Abstract: The Bacajá Domain is located in the eastern portion of the Amazonian Craton, within the Maroni-Itacaúnas Paleoproterozoic province or Transamazon. The current interpretation of the limits between different lithostratigraphic units was based mainly on airborne geophysical data acquired in the 1970s. Between 2004 and 2005 radar (SAR) data were acquired by the Amazon Protection System (SIPAM) and new geophysical data, comprising magnetic and gammaspectrometric data, were acquired by the Geological Survey of Brazil (CPRM). These new data are fundamentally important to advance the geological knowledge and to assess the mineral potential of this region. These data sets were analyzed and spatially modeled for generating geological maps and information on the gold potential of the central Bacajá Domain. The results suggest that the boundary between the Bacajá Domain and the Carajás Province is located between the Pacajá orthogneiss (Neoarchean) and Novolândia granulite (Riaciano). Using fuzzy logic modeling the more favorable areas to the occurrence of mafic and ultramafic rocks were defined, comprising amphibolite, diabase, gabbro and metagabbro. Using Self-organizing Maps (SOM), classes related to the main lithologies that occur in the central Bacajá Domain were defined. Gold occurrences are associated with areas whose gammaespectrometric signatures exhibit high potassium values, characterized also by NW-SE trending lineaments. These characteristics suggest the presence of extensional structures associated with shear zones in the areas of the mafic rocks belonging to the Três Palmeiras Sequence. Based on these results, new proposal is presented for the distribution of the main lithostratigraphic units of the central Bacajá Domain at the scale of 1:100,000 / Doutorado / Geologia e Recursos Naturais / Doutor em Ciências
|
Page generated in 0.1218 seconds