Though stratigraphic correlations are abundant in the Cordilleran basin-fill, they rarely include along-strike transects providing a spatio-temporal sense of deformation, sediment-supply and subsidence. A new, high-resolution, regional strike-correlation of the Castlegate Formation reveals progressive northward-growth of the San Rafael Swell during two embryonic episodes of Laramide-style deformation in central Utah. The intrabasinal deformation-events produced gentle lithospheric-folding punctuated by erosional-truncation of upwarped regions. The earliest episode occurred at 78 Ma in the southern San Rafael Swell likely causing soft-sediment deformation and stratal-tilting. Following this the alluvial-plain was leveled and rapid, extensive-progradation took place. A second episode, at 75 Ma, where deformation was focused in the northern San Rafael Swell, also caused sediment-liquefaction and erosional beveling. The stratal-tilting and sediment-liquefaction is attributed to seismicity induced by basal-traction between a subducting flat-slab and continental-lithosphere. The south-to north time-transgression of uplift is spatio-temporally consistent with NE-propagation of an oceanic-plateau subducted shallowly beneath the region.

La topographie de l’Afrique du Nord est marquée en domaine intraplaque par des bombements topographiques importants, associés à du magmatisme cénozoïque. Le Bouclier Touareg, un de ces bombements, est constitué d’un socle précambrien structuré à l’orogénèse panafricaine et culminant à plus de 2400 m d’altitude. Les séries paléozoïques affleurent actuellement sous forme de cuestas autour de ce bombement topographique. Localement, des témoins sédimentaires d’âge présumé crétacé, en discordance sur le socle précambrien, traduisent l’affleurement de celui-ci au Mésozoïque. Le volcanisme cénozoïque, qui se met également en place sur le socle, est actif entre 35 Ma et aujourd’hui. Afin de mieux contraindre l’évolution du Bouclier Touareg durant le Phanérozoïque, nous avons mené deux études : des travaux de modélisation géophysique, et une étude de thermochronologie basse température. L’étude géophysique a consisté en la modélisation de quatre profils longue distance permettant d’imager la structure lithosphérique. Nous avons montré que le bombement du Hoggar est actuellement soutenu par un important amincissement lithosphérique. En outre, nous avons estimé que sans cet amincissement, la topographie serait négative : le bassin ainsi reconstitué avant amincissement de la lithosphère aurait permis le dépôt d’une couverture sédimentaire d’épaisseur plurikilométrique. L’étude de thermochronologie basse température s’est portée sur deux méthodes : les analyses de traces de fission sur apatite, et les analyses (U-Th)/He sur apatite. Les analyses (U-Th)/He ont montré que le socle du Bouclier Touareg, avant d’avoir subi une importante exhumation à l’Eocène Supérieur, étant enseveli sous une couverture sédimentaire et chauffé à approximativement ~80°C. Les analyses de traces de fission ont permis de préciser que cette phase de chauffe, probablement sous couverture sédimentaire, du Bouclier Touareg a eu lieu entre 100 et 50 Ma. Ainsi, le bombement du Hoggar constituait probablement un bassin sédimentaire de grande dimension au cours du Crétacé supérieur/Paléocène. Ces résultats nous ont permis de discuter des mécanismes géodynamiques possiblement actifs durant le Cénozoïque. Nous proposons que le bombement actuel du Bouclier Touareg, ainsi que son magmatisme, soient liés à des perturbations thermiques des parties superficielles de l’asthénosphère. Ces perturbations seraient induites par d’importantes variations d’épaisseur de la lithosphère saharienne, et pourraient expliquer la présence d’autres bombements en Afrique du Nord. / The North-African intraplate topography is underlined by massive topographic swells associated with Cenozoic volcanism. The Tuareg Shield, which is one of these swells, consists of Precambrian basement which has been structured by the Pan-African orogeny and reaches currently an altitude of 2400 m. The Paleozoic sedimentary series are outcropping as important cuestas surrounding the topographic swell. Locally, some Mesozoic sedimentary remnants, lying unconformably over the basement, testify of its exposure during the Mesozoic. The Cenozoic volcanism, which is also taking place on the basement, shows ages from 35 Ma to Quaternary. In order to improve the knowledge of the Phanerozoic evolution of the Tuareg Shield, we performed two separated studies: geophysical modelling works, and a low temperature thermochronology study. The geophysical study consisted of the modelling of four long-distance profiles allowing imaging the lithospheric structure. We have shown that the Tuareg Shield swell is currently sustained by a strong lithospheric thinning. Moreover, we have estimated that without this thinning, the topography would be negative and that such basin, prior to thinning, would have allowed the deposition of a plurikilometric sedimentary cover. The low temperature thermochronological study has focused on two methods: apatite fission-track analysis, and apatite (U-Th)/He analysis. The latter shown that the Tuareg Shield, before an important Late Eocene exhumation, was buried under a sedimentary cover and heated at ~80°C. The fission-track analyses have shown that this heating stage of the Tuareg Shield, related to burying, occurred from 100 and 50 Ma. Thus, the Tuareg Shield was probably a wide scale sedimentary basin during the Upper Cretaceous – Paleocene. These results allowed us to discuss the geodynamic mechanisms potentially active during the Cenozoic. We proposed that the current doming of the Tuareg Shield, as well as its volcanism, were related to thermal perturbations of the shallower levels of the asthenosphere. These instabilities would have been generated by strong Saharan lithospheric thickness variations, and could explain the presence of others swells in North Africa.

Este trabalho tem como objetivo o desenvolvimento de um método numérico para simular escoamentos viscoelásticos tridimensionais com superfícies livres governados pelo modelo constitutivo Giesekus. As equações governantes são resolvidas pelo método de diferenças finitas numa malha deslocada. A superfície livre do fluido é modelada por partículas marcadoras, possibilitando assim a visualização e localização da superfície livre do fluido. A equação constitutiva de Giesekus é resolvida utilizando as seguintes formulações: método de Runge-Kutta de segunda ordem (também conhecido como método de Euler modificado) e transformação logarítmica do tensor conformação. O método numérico apresentado é verificado comparando-se os resultados obtidos por meio de refinamento de malha para os escoamentos em um tubo e de um jato incidindo em uma placa plana. Resultados de convergência foram obtidos por meio de refinamento de malha do escoamento totalmente desenvolvido em um tubo. Os resultados numéricos obtidos incluem a simulação de um jato incidindo em uma caixa vazia e a simulação do inchamento do extrudado (dieswell) para vários números de Weissenberg utilizando diferentes valores do fator de mobilidade do fluido. Resultados adicionais incluem simulações do fenômeno delayed dieswell para altos números de Weissenberg e altos valores do número de Reynolds. Uma comparação qualitativa com resultados experimentais é apresentada. / In this work, a numerical method for simulating viscoelastic free surface flows governed by the Giesekus constitutive equation is developed. The governing equations are solved by the finite difference method on a staggered grid. The fluid free surface is approximated by marker particles which enables the visualization and location of the free surface fluid. The Giesekus constitutive equation is solved by the following techniques: second-order Runge-Kutta, conformation tensor and logarithmic transformation of the conformation tensor. The numerical method is verified by comparing the numerical solutions obtained on a series of embedding meshes of the flow in a tube and by the flow produced by a jet flowing onto a planar surface. Additional verification and convergence results are obtained by solving tube flow employing several meshes. Results obtained include the simulation of a jet flowing into a three dimensional container and the simulation of extrudate swell using several values of the Reynolds and Weissenberg numbers and different values of the mobility parameter a. Furthermore, we present results from the simulation of the phenomenon know as delayed dieswell using highWeissenberg and Reynolds numbers. Comparisons with experimental results are given.

<p>Many geotechnical engineering problems involve combining two or more independent physical processes as a coupled solution of seepage, volume change and shear strength. For any physical process being modeled, it is desirous to be able to compute any of the volume-mass soil properties. When the volume-mass soil properties are combined with the stress state of the soil, the result is a volume-mass constitutive relationship. Three volume-mass constitutive relationships (i.e., void ratio, water content and degree of saturation) are generally viewed as being the most fundamental; however, only two of the relations are independent. The unsaturated soil properties associated with seepage, volume change and shear strength problems are also related to the volume-mass soil properties. While the unsaturated soil properties are often estimated as simply being a function of the soil-water characteristic curve, it is more accurate to define the properties in a more rigorous manner in terms of the volume-mass soil properties. The advancement of computing capabilities means that it is quite easy to formulate constitutive relations for shear strength and permeability, for example, in terms of all volume-mass properties of the unsaturated soil.</p><p>The objectives of this dissertation include: i) the development of volume-mass constitutive models for unsaturated soils; ii) the further study and verification of the volume-mass constitutive behavior of unsaturated soils; and iii) the development of techniques for visualization of volume-mass constitutive surfaces for unsaturated soils. To achieve these objectives, the present research study was conducted from both theoretical and experimental bases.</p><p>The theoretical program commenced with a comprehensive literature review of the volume-mass constitutive relationships for unsaturated soils. A new, more rigorous volume-mass constitutive model was then proposed. Appropriate terminology was introduced for the development of the model, followed by an outline of the assumptions used and the mathematical derivation. The proposed model requires conventionally obtainable soil properties for its calibration. The model is capable of predicting both the void ratio and water content constitutive relationships for various unsaturated soils, taking into account elastic and plastic volume changes. Various stress paths can be simulated and hysteresis associated with the soil-water characteristic curve can be taken into account. </p><p>Two closed-form equations for the volume-mass constitutive relationships were derived. A computer software program was written based on the theory of the proposed volume-mass constitutive model. Techniques for the visualization of the volume-mass constitutive surfaces were then presented. An experimental program was conducted in the laboratory. The experimental program involved the verification of a new testing apparatus. Several soils were selected for testing purposes and appropriate testing procedures were established (i.e., soil specimens were initially slurry). The testing stress paths followed in the experimental program were different from most research programs conducted in the past and reported in the research literature. Conclusions regarding the compressibility, stress path dependency, and hysteretic nature of the soil-water characteristic curve of an unsaturated soil were presented.</p><p>A considerable number of test results (i.e., from both the experimental program and the research literature) were used in the verification of the new volume-mass constitutive model. This model has proven to be effective in predicting both collapse and expansion of a soil. The volume-mass constitutive model appears to predict behaviour in a satisfactory manner for a wide range of soils; however, the predictions appear to be superior for certain soils. In all cases the volume-mass predictions of the model appear to be satisfactory for geotechnical engineering practice.

The capability to observe ocean swell using spaceborne Synthetic Aperture Radar (SAR) has been demonstrated starting with ERS-1 mission in 1992. This dissertation shows how ocean swell properties can be used to combine swell observations of heterogeneous quality and acquired at various times and locations for the observation and forecast of ocean swell fieldsusing ASAR instrument on-board ENVISAT. The first section is a review of how ocean swell spectra can be derived from the SAR complex images of the ocean surface using a quasi-linear transformation. Then, significant swell heights, peak periods and peak directions from in situ measurements are used to assess the accuracy of the SAR observed swell spectra. Using linear propagation in deep ocean, a new swell field reconstruction methodologyis developed in order to gather SAR swell observations related to the same swell field. Propagated from their generation region, these observations render the spatio-temporal properties of the emanating ocean swell fields. Afterwards, a methodology is developed for the exclusion of outliers taking advantage of the swell field consistency. Also, using the irregularly sampled SAR observations, quality controlled estimations of swell field integral parameters are produced on a regular space-time grid. Validation against in situ measurements reveals the dramatic impact of the density of propagated observations on the integral parameters estimated accuracy. Specifically, this parameter is shown to be very dependent on the satellite orbit. Finally, comparisons with the numerical wave model WAVEWATCH-III prove it could potentially benefit from the SAR swell field estimates for assimilation purposes.

<p>Many geotechnical engineering problems involve combining two or more independent physical processes as a coupled solution of seepage, volume change and shear strength. For any physical process being modeled, it is desirous to be able to compute any of the volume-mass soil properties. When the volume-mass soil properties are combined with the stress state of the soil, the result is a volume-mass constitutive relationship. Three volume-mass constitutive relationships (i.e., void ratio, water content and degree of saturation) are generally viewed as being the most fundamental; however, only two of the relations are independent. The unsaturated soil properties associated with seepage, volume change and shear strength problems are also related to the volume-mass soil properties. While the unsaturated soil properties are often estimated as simply being a function of the soil-water characteristic curve, it is more accurate to define the properties in a more rigorous manner in terms of the volume-mass soil properties. The advancement of computing capabilities means that it is quite easy to formulate constitutive relations for shear strength and permeability, for example, in terms of all volume-mass properties of the unsaturated soil.</p><p>The objectives of this dissertation include: i) the development of volume-mass constitutive models for unsaturated soils; ii) the further study and verification of the volume-mass constitutive behavior of unsaturated soils; and iii) the development of techniques for visualization of volume-mass constitutive surfaces for unsaturated soils. To achieve these objectives, the present research study was conducted from both theoretical and experimental bases.</p><p>The theoretical program commenced with a comprehensive literature review of the volume-mass constitutive relationships for unsaturated soils. A new, more rigorous volume-mass constitutive model was then proposed. Appropriate terminology was introduced for the development of the model, followed by an outline of the assumptions used and the mathematical derivation. The proposed model requires conventionally obtainable soil properties for its calibration. The model is capable of predicting both the void ratio and water content constitutive relationships for various unsaturated soils, taking into account elastic and plastic volume changes. Various stress paths can be simulated and hysteresis associated with the soil-water characteristic curve can be taken into account. </p><p>Two closed-form equations for the volume-mass constitutive relationships were derived. A computer software program was written based on the theory of the proposed volume-mass constitutive model. Techniques for the visualization of the volume-mass constitutive surfaces were then presented. An experimental program was conducted in the laboratory. The experimental program involved the verification of a new testing apparatus. Several soils were selected for testing purposes and appropriate testing procedures were established (i.e., soil specimens were initially slurry). The testing stress paths followed in the experimental program were different from most research programs conducted in the past and reported in the research literature. Conclusions regarding the compressibility, stress path dependency, and hysteretic nature of the soil-water characteristic curve of an unsaturated soil were presented.</p><p>A considerable number of test results (i.e., from both the experimental program and the research literature) were used in the verification of the new volume-mass constitutive model. This model has proven to be effective in predicting both collapse and expansion of a soil. The volume-mass constitutive model appears to predict behaviour in a satisfactory manner for a wide range of soils; however, the predictions appear to be superior for certain soils. In all cases the volume-mass predictions of the model appear to be satisfactory for geotechnical engineering practice.

Thesis (M)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Johnson, Ralph. Includes bibliographical references (leaves [83]-[84]).

Este trabalho tem como objetivo o desenvolvimento de um método numérico para simular escoamentos viscoelásticos tridimensionais com superfícies livres governados pelo modelo constitutivo Giesekus. As equações governantes são resolvidas pelo método de diferenças finitas numa malha deslocada. A superfície livre do fluido é modelada por partículas marcadoras, possibilitando assim a visualização e localização da superfície livre do fluido. A equação constitutiva de Giesekus é resolvida utilizando as seguintes formulações: método de Runge-Kutta de segunda ordem (também conhecido como método de Euler modificado) e transformação logarítmica do tensor conformação. O método numérico apresentado é verificado comparando-se os resultados obtidos por meio de refinamento de malha para os escoamentos em um tubo e de um jato incidindo em uma placa plana. Resultados de convergência foram obtidos por meio de refinamento de malha do escoamento totalmente desenvolvido em um tubo. Os resultados numéricos obtidos incluem a simulação de um jato incidindo em uma caixa vazia e a simulação do inchamento do extrudado (dieswell) para vários números de Weissenberg utilizando diferentes valores do fator de mobilidade do fluido. Resultados adicionais incluem simulações do fenômeno delayed dieswell para altos números de Weissenberg e altos valores do número de Reynolds. Uma comparação qualitativa com resultados experimentais é apresentada. / In this work, a numerical method for simulating viscoelastic free surface flows governed by the Giesekus constitutive equation is developed. The governing equations are solved by the finite difference method on a staggered grid. The fluid free surface is approximated by marker particles which enables the visualization and location of the free surface fluid. The Giesekus constitutive equation is solved by the following techniques: second-order Runge-Kutta, conformation tensor and logarithmic transformation of the conformation tensor. The numerical method is verified by comparing the numerical solutions obtained on a series of embedding meshes of the flow in a tube and by the flow produced by a jet flowing onto a planar surface. Additional verification and convergence results are obtained by solving tube flow employing several meshes. Results obtained include the simulation of a jet flowing into a three dimensional container and the simulation of extrudate swell using several values of the Reynolds and Weissenberg numbers and different values of the mobility parameter a. Furthermore, we present results from the simulation of the phenomenon know as delayed dieswell using highWeissenberg and Reynolds numbers. Comparisons with experimental results are given.

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