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\"Estudo de anomalias gravimétricas e aeromagnéticas das alcalinas morro de engenho e A2, sudoeste de Goiás\" / Study of Gravity and Aeromagnetic Anomalies of Morro do Engenho and A2 Alkalines, SW Goias.Dutra, Alanna Costa 20 April 2006 (has links)
A Província Alcalina Rio Verde - Iporá, na borda norte da Bacia do Paraná é caracterizada pela presença de intrusões alcalinas com forte assinatura aeromagnética e gravimétrica, apresentando-se como anomalias quase circulares. O trabalho refinou o levantamento gravimétrico na região sudoeste de Goiás, incluindo um levantamento de detalhe sobre as intrusões de Morro do Engenho (ME) e uma intrusão a poucos quilômetros a NE de Morro de Engenho (A2), com informações gravimétricas e aeromagnéticas, e sobre a anomalia gravimétrica próxima à cidade de Britânia, sem informação de anomalia aeromagnética. As anomalias gravimétricas variam de 15 a 30 mGal com relação ao campo gravimétrico regional, enquanto que as anomalias aeromagnéticas são da ordem de ±3000nT. Foram feitas também medidas das propriedades petrofísicas de amostras da área. Os resultados da inversão 2D e 3D dos dados gravimétricos e 3D dos dados magnéticos indicam que os corpos alongam-se dentro da crosta superior até a profundidade máxima de 10 km e diâmetro da ordem de 8 km, com geometria aproximadamente cilíndrica. Os dados gravimétricos e aeromagnéticos de ME foram tratados de forma conjunta por modelamento direto (2,5D) onde foi incluída a magnetização remanescente, os resultados obtidos indicam que o volume do corpo anômalo é da ordem de 980 km3. / The Alkaline Province Rio Verde - Iporá, in the north border of the Paraná Basin is characterized by the presence of alkaline intrusions with strong gravity and magnetic signature. This project implemented a gravity survey in the Southwest of Goiás, including a detail one on Morro do Engenho Complex (ME), and one a few kilometers towards NE from ME over an aeromagnetic anomaly known as A2, and over a gravity anomaly close to Britânia city. ME and A2 have magnetic anomaly. The gravity anomalies vary from 15 to 30 mGal in relation to the regional gravity field, while the magnetic anomalies are of the order ±3000nT. Measurements of petrophysical properties of samples from the area were also done. The results present the inversion of the gravity and magnetic data, suggesting that the bodies are inside of the superior crust until the maximum depth of 10 km, in a cylindrical form with 8 to 10 km in diameter. 2.5D direct modeling was also done for ME including remanent magnetization and was performed at the two data sets together, the obtained results indicate that the close volume of the anomalous body it is 980 km3.
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\"Estudo de anomalias gravimétricas e aeromagnéticas das alcalinas morro de engenho e A2, sudoeste de Goiás\" / Study of Gravity and Aeromagnetic Anomalies of Morro do Engenho and A2 Alkalines, SW Goias.Alanna Costa Dutra 20 April 2006 (has links)
A Província Alcalina Rio Verde - Iporá, na borda norte da Bacia do Paraná é caracterizada pela presença de intrusões alcalinas com forte assinatura aeromagnética e gravimétrica, apresentando-se como anomalias quase circulares. O trabalho refinou o levantamento gravimétrico na região sudoeste de Goiás, incluindo um levantamento de detalhe sobre as intrusões de Morro do Engenho (ME) e uma intrusão a poucos quilômetros a NE de Morro de Engenho (A2), com informações gravimétricas e aeromagnéticas, e sobre a anomalia gravimétrica próxima à cidade de Britânia, sem informação de anomalia aeromagnética. As anomalias gravimétricas variam de 15 a 30 mGal com relação ao campo gravimétrico regional, enquanto que as anomalias aeromagnéticas são da ordem de ±3000nT. Foram feitas também medidas das propriedades petrofísicas de amostras da área. Os resultados da inversão 2D e 3D dos dados gravimétricos e 3D dos dados magnéticos indicam que os corpos alongam-se dentro da crosta superior até a profundidade máxima de 10 km e diâmetro da ordem de 8 km, com geometria aproximadamente cilíndrica. Os dados gravimétricos e aeromagnéticos de ME foram tratados de forma conjunta por modelamento direto (2,5D) onde foi incluída a magnetização remanescente, os resultados obtidos indicam que o volume do corpo anômalo é da ordem de 980 km3. / The Alkaline Province Rio Verde - Iporá, in the north border of the Paraná Basin is characterized by the presence of alkaline intrusions with strong gravity and magnetic signature. This project implemented a gravity survey in the Southwest of Goiás, including a detail one on Morro do Engenho Complex (ME), and one a few kilometers towards NE from ME over an aeromagnetic anomaly known as A2, and over a gravity anomaly close to Britânia city. ME and A2 have magnetic anomaly. The gravity anomalies vary from 15 to 30 mGal in relation to the regional gravity field, while the magnetic anomalies are of the order ±3000nT. Measurements of petrophysical properties of samples from the area were also done. The results present the inversion of the gravity and magnetic data, suggesting that the bodies are inside of the superior crust until the maximum depth of 10 km, in a cylindrical form with 8 to 10 km in diameter. 2.5D direct modeling was also done for ME including remanent magnetization and was performed at the two data sets together, the obtained results indicate that the close volume of the anomalous body it is 980 km3.
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Geoelectrical approaches for characterizing soil geochemical processes and soil-root interactions / Approches géoélectriques pour l'étude du sol et d'interaction sol-racinesPeruzzo, Luca 20 June 2019 (has links)
Cette thèse porte sur les possibilités que les méthodes d’imagerie géoélectrique offrent à la fois pour la caractérisation des processus géochimiques mais aussi pour l’étude d’interaction sol-racines. La ligne conductrice de ce travail, repose sur la position centrale de la qualité des sols et des interactions racines-sols dans de nombreux problèmes environnementaux. En effet, un nombre croissant d’études rapportent l’importance des interactions mutuelles entre les racines et le sol. Dans cette optique, cette thèse explore l’utilisation le développements approfondis de méthodes géoélectriques. Les processus physico-chimiques ainsi que les interaction sol-racines sont à l’origine de mouvement d’eau et de soluté, d’altération de la structure des sols ainsi que de perturbations biologiques. Les méthodes géoélectriques sont potentiellement sensibles à ces modifications hydrologique et biochimique. La méthode de Polarisation Provoquée Spectrale (PPS) a été combinée avec des analyses et des modélisations géochimiques permettant de connaitre sa sensibilité à la composition du fluide interstitiel (contenu dans l’espace poral), du pH et de la force ionique. Plus particulièrement, la signature PPS de la substitution Na+/Cu2+ a été analysée car il s’agit d’un critère pertinent traduisant la qualité d’un sol et reconnu mondialement. L’analyse PPS a été réalisée sur un sable (silicate) saturé et pour des concentrations typiques de Na+/Cu2+ que l’on trouve classiquement dans des sols exposés à des utilisations de pesticides au Cuivre (Cu). Les résultats ont montré que le pH et la force ionique ont été les variables prépondérantes contrôlant le signal PPS, alors que des effets négligeables sont liés à la substitution Cu/Na. L’utilisation simultanée d’analyses chimiques et géophysiques en laboratoire a permis de mieux caractériser les processus de complexation étudiés et d’appuyer considérablement l’interprétation des signaux PPS. Enfin, la tomographie de résistivité électrique et la méthode de Mise-A-La-Masse ont été combinées pour développer une nouvelle approche d'imagerie du chemin préférentiel emprunté par le courant électrique dans le système racines-sols. Etant donné que la conduction électrique dans le sol et les racines est principalement électrolytique, l'approche proposée repose sur le mouvement de l'eau et des solutés dans le système racines-sol. Le potentiel de la méthode pour son application in-situ a été testée à l’aide d’une série d’expériences sur une vigne. À la suite des résultats prometteurs, la méthode a été développée et appliquée lors d’une expérience en laboratoire portant sur la croissance racinaire dans un rhizotron de plantes de coton et de maïs. La méthode s'est révélée sensible aux différences physiologiques entre les espèces et éventuellement à la réponse de la plante aux facteurs de stress environnementaux. De nouvelles expériences contrôlant les variables physiologiques des tissus racinaires sont nécessaires pour une meilleure compréhension de leurs influences. Les développements technologiques récents soutiennent fortement la diffusion de l’imagerie et du suivi géoélectriques à l'échelle du terrain. Dans ce contexte prometteur, les résultats de cette thèse contribuent au développement d'approches géoélectriques pour l'étude du sol et de ses interactions mutuelles avec les racines des plantes à des échelles spatio-temporelles pertinentes. / In this thesis I investigate some of the possibilities offered by the use of geoelectrical methods for characterizing soil geochemical processes and root-soil interactions. The motivation for this thesis arises from the pivotal role of soil quality and root-soil interactions in manifold environmental issues. In addition, there is growing evidence of the importance of mutual interactions between roots and soil, for this reason this thesis explores the use of geoelectrical methods for more comprehensive approaches. Both soil physicochemical processes and root-soil interactions involve, among others, the movement of water and solutes, altercations of the soil structure, and biological feedbacks. Geoelectrical methods are potentially sensitivity to these hydrogeological and biogeochemical modifications. The Spectral Induced Polarization (SIP) method was combined with geochemical analyses and modeling in order to investigate its sensitivity to pore fluid composition, pH, and ionic strength. In particular, the SIP signature of Na+/Cu2+ substitution was investigated because of their worldwide relevance for soil quality. The SIP investigation focused on saturated silica, and explored concentrations of Na+ and Cu2+ that are typical to agricultural soils exposed to the use of Cu pesticides. The results showed how pH and ionic strength were the main variables controlling the SIP signals, while negligible effects were related to the Cu/Na substitution. The concurrent use of chemical and geophysical laboratory experiments allowed a better characterization of the investigated complexation processes and significantly supported the interpretation of the SIP signals. The Electrical Resistivity Tomography and the Mise-A-La-Masse methods were combined to develop a novel approach for imaging the electric current pathways in the root-soil system. Since the current conduction in soil and roots is mostly electrolytic, the proposed approach relates to the movement of water and solutes within the root-soil system. The potential of the method for field investigations was explored with a set of experiments on a grapevine. In light of the promising results, the method was further developed and applied to rhizotron laboratory experiments on cotton and maize plants. The method proved to be sensitive to inter-species physiological differences and possibly to the plant response to environmental stressors. New experiments with physiological analyses of root tissues are needed to elucidate these aspects. Emerging technologies are strongly supporting to the diffusion of imaging and monitoring geoelectrical applications at the field-scale. In this promising context, the results of this thesis contribute to the development of geoelectrical approaches for studying soil and its mutual interactions with plant roots over relevant spatiotemporal scales.
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