Le périmètre de recherche faisant l'objet de mon mémoire a été établi de façon à déterminer la structure de ces deux ensembles géologiques et leurs relations. Ce travail a été réalisé sur la base des levés cartographiques à l'échelle du 20 000ème qui seule permet de saisir les relations géométriques des différents éléments structuraux de ce secteur. Les levés géologiques couvrent partiellement les feuilles de Castellane 6 et 7 et de Fayence 2 et 3 . L'analyse de mon secteur de recherche a été abordée principalement sur son aspect structural et stratigraphique. L'étude de cette région, au même titre que toute la bordure externe de l'arc de Castellane est primordiale pour contribuer à la compréhension de la genèse des chaînes subalpines méridionales. Il était intéressant de subdiviser les différents évènements tectoniques et de retrouver dans les divers ensembles structuraux la part qui leur revient. L'hétérogénéité des structures appelait en outre une explication plus complète que celle des auteurs précédents: il importait en particulier de redéfinir le style et les modalités de la superposition des différentes déformations et de préciser leur âge. En ce qui concerne la stratigraphie, celle des séries marines mésozoïques a été établie depuis longtemps, tout au moins dans ses grandes lignes. En revanche, celle des bassins tertiaires continentaux regroupés dans une formation unique sur les cartes existantes nécessitait une révision complète. L'analyse de ces séries m'a permis d'individualiser plusieurs formations distinctes et de montrer leur lien étroit avec les diverses pulsations tectoniques.

A prominent landslide deposit in the Slope Basin seaward of the Megasplay Fault in the Nankai Trough was emplaced by a high-mobility landslide based on analysis of physical properties and seismic geomorphology. Slide acceleration is a critical variable that determines amplitude of slide-generated tsunami but is many times a variable with large uncertainty. In recent controlled laboratory experiments, the ratio of the shear stress to yield strength (defined as the Flow Factor) controls a wide spectrum of mass movement styles from slow, retrogressive failure to rapid, liquefied flows. Here, we apply this laboratory Flow Factor approach to a natural landslide in the Nankai Trough by constraining pre-failure particle size analysis and porosity. Several mass transport deposits (MTDs), were drilled and cored at Site C0021 in the Nankai Trough during International Ocean Discovery Program (IODP) Expedition 338. The largest, MTD B, occurs at 133-176 meters below seafloor and occurred approximately 0.87 Mya. Slide volume is 2 km3, transport distance is 5 km, and average deposit thickness is 50 m (maximum 180 m). Pre-failure water content was estimated from shallow sediments at Site C0018 (82%). The average grain size distribution is 37% clay-sized, 60% silt-sized, and 3% sand-size particles as determined by hydrometer analyses of the MTD. Together, the water content and clay fraction predict a Flow Factor of 3.5, which predicts a relatively high mobility slide. We interpret that the landslide that created MTD B was a single event that transported the slide mass relatively rapidly as opposed to a slow, episodic landslide event. This is supported by the observation of a completely evacuated source area with no remnant blocks or retrogressive headscarp and an internally chaotic seismic facies with large entrained blocks. This approach can be extended to other field settings characterized by fine-grained siliciclastics and where water content and clay percentages are known.

The groundwater flow in aquifers contain evaporite rocks can cause problems such as geo-mechanical subsidence or collapse. In this work, we focus on the development of numerical models to simulate the flow in porous and non-porous domains in order to study the dissolution phenomenon and fractures evolution over time. The first part of this thesis is devoted to developing new solutions for the validation of numerical models to simulate density driven flow in porous media. The new procedure consist of solving simultaneously the flow and the transport equations using the Levenberg-Marquardt algorithm. The use of this technique allowed us to develop, for the first time, semi-analytical solutions of saltwater intrusion in the case of small diffusion and in the case of a large density contrast. In the second part of this work, we studied the flow in evaporitic rocks. A numerical code was developed to solve the nonlinear system using advanced numerical methods. To validate this new model, we have developed a semi-analytical solution for the density Stokes flow. The third part of this work is devoted to transport with dissolution of rock salt. As a first step, we studied the influence of various parameters on the dissolution of salt in Adlertunnel located at a depth of 160 m in the region of Basel in Switzerland. In a second step, we are interested in the simulation of the fracture's evolution as a result of the dissolution. The numerical model takes into account the Stokes flow and mass transport effects and dissolution of the fracture walls.

Karst environments are interconnected landscapes vulnerable to degradation. Many instances of anthropogenic karst disturbance are unintentional, and occur because of the public's lack of understanding or exposure to karst knowledge. When attempts are made to educate the general public about these landscapes, the concepts taught are often too abstract to be fully understood. Thus, karst educational pursuits must use only the most efficient and effective learning materials. A technique useful for assessing educational effectiveness of learning materials is eye-tracking, which allows scientists to quantitatively measure an individual's points of interest and eye movements when viewing a 2D or 3D visualization. Visualization developers use eye-tracking data to create graphics that hold the observer's attention and, thereby, enhance learning about a particular concept. This study aimed to assess and improve the educational effectiveness of 2D karst visualizations by combining eye-tracking techniques with Geographic Information Systems, knowledge assessments, and semi-structured interviews. The first phase of this study consisted of groups of 10 participants viewing 2D karst visualizations with one category of manipulated visual stimuli. The second phase consisted of groups of 10-15 participants viewing 2D karst visualizations that were created based on the results from the first phase. The results of this study highlighted both effective stimuli in karst visualizations and stimuli that hinder the educational effectiveness of visualizations.

The Tally Ho shear zone (THSZ) is a 40-kilometre long, northwest-striking assemblage of highly-deformed rocks outcropping along the western margin of Stikinia in southern Yukon. The location of the THSZ adjacent to the boundary between the oceanic Stikine Terrane and pericratonic Nisling Assemblage of the Yukon-Tanana Terrane provides an opportunity to examine the tectonic significance of a terrane-marginal high-strain structure. Detailed geological mapping along the THSZ and adjacent rocks indicates that the shear zone is a crustal-scale thrust fault that places deep-seated arc rocks of Stikinia up-section and to the east onto a package of upper crustal volcanic and volcaniclastic rocks of the Upper Triassic Lewes River Group. Timing of movement along the THSZ is constrained by U-Pb zircon age determinations of a deformed section of cumulate leucogabbro in the hangingwall of the shear zone (208 ± 4.3 Ma) and by a post-kinematic cross-cutting megacrystic granite intrusion (~173 Ma). Positive Nd values of Stikine magmatic rocks (+4.5 to +6.7) indicate magmas forming the oceanic terrane were formed with little to no input of continental crust until around the time of intrusion of a megacrystic granite unit in the mid-Jurassic (Nd -4.0). The THSZ is therefore interpreted to have formed in response to the thick-skinned collision and underpinning of the Nisling Assemblage beneath western Stikinia in the Early Jurassic resulting in the imbrication of the Stikine magmatic arc along the THSZ.

The Malay and Penya Basins, offshore Peninsular Malaysia, were formed during the early Oligocene as a result of regional dextral shear deformation caused by the indentation of India into Eurasia in the early Tertiary. Pre-existing basement inhomogeneities exerted a strong control on basin development. The Penyu Basin developed, initially, as isolated grabens and half-grabens at basement fault intersections, in response to roughly N-S extension. The major structures which include low-angle listric normal faults, pull-apart rhomb grabens and flower structures, suggest that "thin-skinned" crustal extension and strike-slip tectonics have played an important role in basin evolution. Basement faults in the Malay Basin are oblique (E-W trending) to the basin trend (NW-trending). The Basin developed by transtension of NW-trending sinistral shear zone, in which fault-bounded blocks rotate in response to the shear deformation, producing a series of E-trending half-graben depocentres. The Basins were subjected to transpressive inversion during the middle-late Miocene, as a result of rotation of the regional stress field, caused by progressive indentation of India into Eurasia. Subsidence analysis suggests that lithospheric stretching was the dominant process of basin formation. The high heat flows (85-100 mW m⁻²) are consistent with stretching factors, β, of 1.2 to 4.3. In the Malay Basin, uplift of the basin flanks preceeded subsidence during the rifting phase as a result of non-uniform stretching and lateral heat flow from the centre of the Basin. Both basins are undercompensated isostatically and characterised by low negative free-air gravity anomaly in the order of -20 mGal. Undercompensation suggests that the basins were formed, partly, by "thin-skinned" crustal extension which did not involve stretching of the subcrustal lithosphere.

Le rift de Corinthe (Grèce) a été depuis longtemps identifié comme un site d'importance majeure en Europe en raison de son activité tectonique intense. Il est l'une des régions continentales s'étendant plus rapidement dans le monde et il a l'un des taux les plus élevés de sismicité dans la région euro-méditerranéenne. Les études menées par GPS depuis 1990 indiquent un taux d'extension nord-sud à travers le rift d'environ 1,5 cm/an à son extrémité occidentale. Les observations géologiques montrent que la côte sud du rift connaît un mouvement de surrection alors que la côte nord est en subsidence. A la terminaison occidentale du rift, plusieurs failles actives se situent au voisinage ou à l'intérieur même de la ville de Patras qui se trouve exposée à un aléa sismique important. Le séisme de Movri (Achaïa) en juin 2008 et l'essaim sismique d'Efpalion (Fokida) en janvier 2010, survenus à quelques dizaines de kilomètres de Patras, ont attiré l'attention scientifique et sociétal sur cette région et apporté des éléments nouveaux à la connaissance géophysique de la région. La présence d'une pluralité de phénomènes géophysiques et les caractéristiques morphologiques font de cette région de Patras, et plus généralement du rift de Corinthe, un laboratoire naturel exceptionnel qui est devenu depuis vingt ans le lieu d'initiatives internationales coordonnées dans le Laboratoire du Rift de Corinthe et reconnu comme un Supersite par les agences spatiales. Sur le terrain des campagnes de mesures géodésiques et sismologiques ont eu lieu depuis 1990 et des réseaux permanents ont été déployés à partir de 2000. Dans le domaine de la télédétection, des données SAR sont disponibles depuis 1992 et la mission ERS1. Motivé par l'absence d'une cartographie précise et étendue de la déformation verticale de la zone et par les limitations du réseau GPS (en termes de densité de points) nous étudions, modélisons et interprétons un nombre important de données d'interférométrie SAR complétées par les données du réseau GPS. Les données d'interférométrie SAR sont très puissantes pour mesurer les mouvements verticaux, pour cartographier les déformations localisées sur des discontinuités, failles ou autres, pour cartographier et modéliser la déformation co-sismique produite par les tremblements de terre. Nous avons traité des données ascendantes et descendantes du capteur ASAR embarqué sur ENVISAT dans la période 2002-2010, et produit des cartes de vitesses (et séries temporelles) de points persistants (Permanent Scatterers) d'une part, de régions cohérentes (SBAS, Small Baseline Subsets) d'autre part. Ces deux types de cartes ont été combinés ainsi que contraint par les observations GPS afin d'en extraire les composantes verticales et est-ouest du champ de vitesses. Dans l'ensemble la chaîne de calcul fonctionne convenablement sur la région pourtant affectée par de nombreuses zones couvertes de végétation et par un relief important. Les résultats paraissent précis et robustes dans de nombreuses zones dans lesquelles le mouvement du sol était auparavant inconnu ou mal connu. Nous avons vérifié l'accord entre le GPS et les vitesses déduites de l'interférométrie radar, et comparés nos résultats avec ceux d'études indépendantes. Nous nous sommes concentrés sur des études de cas spécifiques et nous présentons les taux de déformation le long des sections transversales dans les zones de la ville de Patras, des abords du pont de Rion-Antirion, des centres urbains de Psathopyrgos, Aigion, Sellianitika, Nafpaktos, Akrata, de l'île de Trizonia ainsi que des deltas de Psathopyrgos, Sellianitika, Aigion, Mornos, Marathias et Akrata. Des déformations du sol apparaissent à l'intérieur même de la ville de Patras. Il s'agit non seulement de subsidences urbaines souvent observées ailleurs, mais aussi de mouvements de blocs superficiels vraisemblablement induits par les mouvements tectoniques profonds à la jonction entre une zone de faille décrochante, provenant de la zone de Movri et entrant à terre entre Rio et Patras (faille en trans-tension de Rio-Patras), et la faille normale de Psathopirgos à l'entrée du rift de Corinthe. La faille de Rio-Patras apparaît comme une structure de transition, oblique, entre le décrochement au sud et l'extension à l'est. La faille d'Aigion apparaît très active avec un taux de soulèvement d'environ 2mm/an, le taux le plus élevé observé dans l'ensemble du rift de Corinthe dans la période échantillonnée, ce soulèvement s'amortissant dans les trois kilomètres séparant cette faille de celle d'Hélike ouest. Les discontinuités observées dans le champ de déformation ne sont pas toujours corrélées avec une activité sismique enregistrée dans la même zone au cours de la période d'investigation. Le delta de Temeni-Valimitika, à l'est d'Aigion, est le seul delta de la zone qui ne subside pas (au moins dans sa plus grande partie). Nous pensons que c'est parce qu'il est situé sur le 'footwall' de la faille d'Aigion et que le processus de compaction/subsidence y est compensé par le processus de soulèvement tectonique dû à la faille. Tous les autres deltas sont en subsidence, en raison vraisemblablement du tassement de leurs sédiments, et dans les plus grands d'entre eux, il est possible d'observer une augmentation linéaire du taux de subsidence entre le bord intérieur du delta et sa côte. Les séismes survenus en 2008 et 2010 dans la zone d'étude sont modélisés par inversion de leurs paramètres de sources en utilisant un modèle de dislocation dans un demi-espace élastique homogène contraint par les données sismologiques, les données GPS et les données d'interférométrie SAR. La plupart des objets tectoniques que nous avons étudiés sont des éléments d'un point triple (diffus) séparant trois micro-plaques situées à la frontière entre le rift de Corinthe à l'est et la terminaison de l'arc hellénique à l'ouest. Nous avons brièvement étudié et discutons les déformations observées par interférométrie radar au sud de lac Trichonis et dans le graben Aitolien au nord d'Etoliko, c'est-à-dire dans la partie nord-ouest du point triple Enfin, pour être complet, et afin d'évaluer les capacités de la géodésie spatiale, nous présentons des discontinuités probablement dues à des glissements de terrain et quelques unes d'origine incertaine et requérant des investigations plus approfondies.

Geodynamic modelling, via computer simulations, offers an easily controllable method for investigating the behaviour of an Earth system and providing feedback to conceptual models of geological evolution. However, most available computer codes have been developed for engineering or hydrological applications, where strains are small and post-failure deformation is not studied. Such codes cannot simultaneously model large deformation and porous fluid flow. To remedy this situation in the face of tectonic modelling, a numerical approach was developed to incorporate porous fluid flow into an existing high-deformation code called Ellipsis. The resulting software, with these twin capabilities, simulates the evolution of highly deformed tectonic regimes where fluid flow is important, such as in mineral provinces. A realistic description of deformation depends on the accurate characterisation of material properties and the laws governing material behaviour. Aside from the development of appropriate physics, it can be a difficult task to find a set of model parameters, including material properties and initial geometries, that can reproduce some conceptual target. In this context, an interactive system for the rapid exploration of model parameter space, and for the evaluation of all model results, replaces the traditional but time-consuming approach of finding a result via trial and error. The visualisation of all solutions in such a search of parameter space, through simple graphical tools, adds a new degree of understanding to the effects of variations in the parameters, the importance of each parameter in controlling a solution, and the degree of coverage of the parameter space. Two final applications of the software code and interactive parameter search illustrate the power of numerical modelling within the feedback loop to field observations. In the first example, vertical rheological contrasts between the upper and lower crust, most easily related to thermal profiles and mineralogy, exert a greater control over the mode of crustal extension than any other parameters. A weak lower crust promotes large fault spacing with high displacements, often overriding initial close fault spacing, to lead eventually to metamorphic core complex formation. In the second case, specifically tied to the history of compressional orogenies in northern Nevada, exploration of model parameters shows that the natural reactivation of early normal faults in the Proterozoic basement, regardless of basement topography or rheological contrasts, would explain the subsequent elevation and gravitationally-induced thrusting of sedimentary layers over the Carlin gold trend, providing pathways and ponding sites for mineral-bearing fluids.

The Tally Ho shear zone (THSZ) is a 40-kilometre long, northwest-striking assemblage of highly-deformed rocks outcropping along the western margin of Stikinia in southern Yukon. The location of the THSZ adjacent to the boundary between the oceanic Stikine Terrane and pericratonic Nisling Assemblage of the Yukon-Tanana Terrane provides an opportunity to examine the tectonic significance of a terrane-marginal high-strain structure. Detailed geological mapping along the THSZ and adjacent rocks indicates that the shear zone is a crustal-scale thrust fault that places deep-seated arc rocks of Stikinia up-section and to the east onto a package of upper crustal volcanic and volcaniclastic rocks of the Upper Triassic Lewes River Group. Timing of movement along the THSZ is constrained by U-Pb zircon age determinations of a deformed section of cumulate leucogabbro in the hangingwall of the shear zone (208 ± 4.3 Ma) and by a post-kinematic cross-cutting megacrystic granite intrusion (~173 Ma). Positive Nd values of Stikine magmatic rocks (+4.5 to +6.7) indicate magmas forming the oceanic terrane were formed with little to no input of continental crust until around the time of intrusion of a megacrystic granite unit in the mid-Jurassic (Nd -4.0). The THSZ is therefore interpreted to have formed in response to the thick-skinned collision and underpinning of the Nisling Assemblage beneath western Stikinia in the Early Jurassic resulting in the imbrication of the Stikine magmatic arc along the THSZ.

O trabalho foi desenvolvido no litoral norte do estado de São Paulo, onde ocorrem boas exposições de rochas intrusivas da porção meridional do Enxame de Diques da Serra do Mar, de idade eocretácica. O objetivo principal da dissertação é caracterizar os regimes tectônicos associados à colocação e à deformação de diques máficos na área de São Sebastião (SP) e sua distribuição espacial, a partir de interpretações de imagens de sensores remotos, análise de dados estruturais de campo e descrição petrográfica das rochas ígneas. A área apresenta grande complexidade no tocante ao magmatismo, uma vez que ocorrem diques de diabásios toleítico e alcalino, lamprófiro e rochas alcalinas félsicas como fonolitos, traquitos e sienitos, estes sob a forma diques, sills e plugs. Os diabásios toleíticos tem idades em torno 134 Ma, correlatas com o início do rifteamento sul-atlântico, enquanto que as rochas alcalinas datam de 86 Ma e estão relacionadas com um magmatismo intraplaca posterior. Os lineamentos estruturais orientam-se majoritariamente na direção ENE-WSW, paralela às foliações metamórficas e zonas de cisalhamento observadas no campo e descritas na literatura, referentes ao Domínio Costeiro da Faixa Ribeira. Os diques se orientam na direção NE-SW, com azimute semelhante porém ângulos de mergulho discordantes da foliação em grande parte da área, onde as foliações são de baixo ângulo. Um segundo conjunto de lineamentos orientado NW-SE ocorre como um importante conjunto de fraturas que cortam tanto as rochas do embasamento proterozóico quanto as rochas alcalinas neocretácicas. Diques com esta orientação são escassos. Um terceiro conjunto NNE-SSW ocorre na porção oeste da área, associado à presença de diques de diabásio que por vezes mostram indicadores de movimentação sinistral. A análise cinemática dos diques mostra um predomínio de distensão pura durante sua colocação, com um tensor de compressão mínima de orientação NW-SE, ortogonal ao principal trend dos diques. Componentes direcionais, por vezes ambíguas, são comumente observadas, com um discreto predomínio de componente sinistral. O mesmo padrão cinemático é observado para os diques toleíticos e para os alcalinos, sugerindo que o campo de tensões local pouco variou durante o Cretáceo. Embora o embasamento não tenha sido diretamente reativado durante a colocação dos diques, sua anisotropia pode ter controlado de certa forma a orientação do campo de tensões local durante o Cretáceo. Os mapas geofísicos da bacia de Santos existentes na literatura sugerem certo paralelismo entre as estruturas observadas na área de estudo e aquelas interpretadas na bacia. As estruturas NNE-SSW são paralelas ao trend das sub-bacias e ao gráben de Merluza, enquanto que as estruturas NW-SE são paralelas a zonas de transferência descritas na literatura. / The study was developed at the northern coast of São Paulo state, southeastern Brazil, where there are good exposures of intrusive rocks of the southern portion of the Early Cretaceous Serra do Mar Dyke Swarm. The main purpose is to define the tectonic regimes related to the emplacement and deformation of mafic dykes in the area of São Sebastião (SP) and their spatial and relative temporal distribution, based on interpretations of remote sensing images, field analysis of structural data, and petrographic description of igneous rocks. The area is quite complex in terms of Cretaceous magmatim, since there are dolerite dykes (tholeiitic and alkaline), lamprophyric dykes and felsic alkaline rocks (mainly phonolites, trachytes and syenites) which occur as dykes, sills and plugs. The tholeiitic dolerites yield ages around 134 Ma, related to the early South Atlantic rifting, while the alkaline rocks are dated as 86 Ma and are related to a subsequent intraplate magmatism. The structural lineaments are oriented mostly ENE-WSW, parallel to the metamorphic foliation and shear zones observed in the field and described in the literature, as part of the Costeiro Complex of the Ribeira Belt. The dykes are oriented NE-SW, with similar azimuth but different dip angles compared to the foliations, which are gently dipping in many areas. A second set of lineaments oriented NW-SE occurs as a major set of brittle fractures which cut both the Proterozoic rocks and the Late Cretaceous alkaline rocks. Dykes with this orientation are scarce. A third set oriented NNE-SSW occurs in the western area associated with some dolerite dykes which sometimes show evidence of sinistral component during emplacement. The kinematic analysis of the dykes shows a predominance of pure extension during emplacement, with an extension direction oriented NW-SE, orthogonal to the main dyke trend. Directional components, sometimes ambiguous, are commonly observed, with a slight predominance of sinistral components. The same kinematic pattern is observed for both tholeiitic and alkaline dykes, so that the local stress field orientation remained unaltered during the Cretaceous. Although the basement has not been directly reactivated during dyke emplacement, their anisotropies can account for some control on the orientation of the local stress field during the Cretaceous. The available geophysical maps of the Santos Basin suggest certain parallelism among the structures observed in the study area and those interpreted in the basin. The NNE-SSW trending structures are parallel to the trend of sub-basins and to the Merluza graben, while the NW-SE structures are parallel to transfer zones described in the literature.