Ce travail analyse l'ensemble des paramètres nécessaires à la compréhension du mécanisme de la formation des cirques et des mouvements de versants actuels qui s'y rattachent, ceci en vue d 'y définir les conditions géotechniques indispensables au zonage du risque, comme à tout projet d ' aménagement. * La première partie présente les traits généraux de l'île, l'occupation du sol des cirques et souligne les particularités hydro-météorologiques. * La deuxième partie concerne tous les événements géologiques qui se sont produits avant l'arrêt de l'activité volcanique du Piton des Neiges , vers 25 000 ans BP , On y expose le contexte géotectonique , puis les données lithostratigraphiques et structurales, ainsi que l'altération hydrothermale subie par les matériaux originels, en faisant ressortir les faits géologiques qui ont une incidence marquée sur les caractéristiques géotechniques globales du massif. * La troisième partie analyse les modalités de l'action des principaux agents morphogénétiques présidant à l ' évolution des reliefs, lors des périodes de calme éruptif, et aboutit à une interprétation des mécanismes de la naissance et du développement des cirques . * la quatrième partie exploite le schéma de distribution spatiale et temporelle issu des analyses précédentes pour une analyse de la dynamique et de l'érosion des versants, une classification géotechnique des terrains et une méthodologie de zonage du risque

The style of the Swedish writer Harry Martinson is characterised by a large number of conspicuous and creative word-formation units, which have a special function in his writing. One single word might summarise and denominate an experiance or a complex emotion, sometimes using an exact description, sometimes using a metaphor. The content and the novelty of such nonce forms catch the reader´s or listener´s attention, achieving the intended effect: to make the reader understand what Martinson wants to convey. The present study is an analysis of the neologisms used in two of Martinson´s semiautobiographical novels and their German translations. The object of the study is twofold: firstly to show that the great variety of nonce words-formations as well as their semantics provide the special stylistic markers of the texts, and secondly to draw more general conclusions about the effect of target languages regarding the form, content and function of the units in the texts, as well as their effect on the reader, the concept of equivalence is central. Correspondences and deviations are analysed applying a model specifically designed for the purpose and based in relevant theories. The results illustrate both the various problems a translator must seek to solve and the consequences that simplifications, omissions, and paraphrases might have on the meaning and effect of the text.

Cette thése étudie l'hydrogéologie des formations de la plaine de Bièvre ( terrases) et du plateau de Chambaran ( formations quaternaires) et de leur substratum : sables, conglomérats et argiles.

A detailed structural analysis was conducted of the Warwick Hills at the northeast tip of the doubly-plunging Dagger Flat anticlinorium, Marathon Basin, west Texas. Field work delineated a folded duplex structure composed of three horses. Thrust transport was towards the northwest and resulted in a hinterland-dipping duplex. Initial thrusting In the Warwick Hills shortened the area by 2.2:1 (54%). Post-thrusting, the duplex underwent nearly isoclinal folding creating two anticlines and a syncline, second-order folds to the Dagger Flat anticlinoium. Folding combined with thrusting brought the total shortening of the rock package to 6.5:1 (85%). Earlier estimates gave a shortening for the Warwick Hills of 3:1. Finally, the folded duplex was extended by oblique tear faulting that offset the folded thrusts accommodating extension of the major folds in a northeast direction. These tear faults occurred post-plunging of the folds and were the last deformational movements that affected the Warwick Hills. The Ordovician Maravillas and Devonian Caballos Formations acted in the Warwick Hills as a structurally competent couplet. Addition or subtraction of this couplet, or units in this couplet, controlled the location of the major and minor thrusts, the style and shape of folds, and the location of the fold hinges. Bounding the couplet are incompetent shales of the Ordovician Woods Hollow and the Mississippian Tesnus Formations. Thrusts in the Warwick Hills duplex have a basal décollement in the Woods Hollow shale and ramp up through the Maravillas/Caballos couplet with an upper décollement in the Tesnus shale. The entire duplex was primarily folded by flexural slip (i.e. concentric folds) as evidenced by slickensides oriented parallel to bedding and perpendicular to fold axes, the constant thickness of the competent layers and the change in fold shape with depth. Fold wavelength, as determined from the couplet in the lowest thrust sheet, averages ~1,300 m and the average fold axis for the Warwick Hills, as determined stereographically, plunges ~54° N90°E. Shale in the Woods Hollow and Tesnus Formations bounding the couplet, flowed passively during folding into the cavities that were created by the bending of the more competent units. Lower and upper boundaries of disharmonic folding developed in the Woods Hollow and Tesnus Formations respectively. Unique to this area when compared to the rest of the anticlinorium are the presence of tightly folded thrusts and steep east-trending fold axes. The anticlinorium plunges in the Warwick Hills because it drapes off a down-to-the-northeast basement fault. Folds were "dragged" or diverted to the east during thrusting of the duplex over this transversely-oriented paleotopographic fault scarp, or were diverted subsequent to thrusting of the duplex by strike-slip movements at depth along the basement fault. / text

No description available.

It is the study of banded iron formations (BIFs) that provides understanding into the conditions of the Earth's oceans and atmosphere during the Archean and Early Proterozoic. The aim of this thesis is to provide a detailed mineralogical and geochemical understand of BIFs from two separate localities separated by the Archean Proterozoic boundary. Close attention is paid to their carbonate and iron oxide mineralogy.The BIFs of the 2.7 Ga Manjeri Formation, Zimbabwe and 2.4 Ga Itabira Group, Brazil were both precipitated from oxygenated mixed marine-hydrothermal fluids. This is demonstrated by the presence of nano-hematite inclusions in the chert (Itabira and Manjeri) and dolomite (Itabira only) laminae, which is interpreted as the oldest mineral phase within the samples. Additionally, focused ion beam transmission electron microscopy (FIB-TEM) reveals the presence of nano ferrihydrite platelets within the dolomitic BIFs (carbonate itabirite). The dolomite is interpreted to be a primary phase precipitated at higher temperatures (~100°C) from CO2-rich hydrothermal fluids. Positive Eu anomalies in both formations indicate a hydrothermal component, likely to be the source of the reduced iron. Facies changes in both units are the result of transgression/regression and post depositional hydrothermal events mask primary conditions. Iron-rich carbonates in both facies have different origins; diagenetic (Itabira) and post depositional hydrothermal (Manjeri). However, the iron-rich carbonates of both formations have negative ∂13C values, indicating that at least part of the carbon in the carbonates is of organic origin. Curie Balance analyses into the carbonate itabirite reveals that maghemite is the transformation product of the ferrihydrite when dolomite decomposes at ~790°C. The maghemite has a Curie temperature between 320 and 350°C and is stable up to temperatures of 925°C.FIB-TEM investigations into the martitisation process revealed two possible mechanisms from two martite samples, from Brazil and India. Depending of the cause of the martitisation, here found to be deformation and hydrothermalism, the martitisation occurs respectively via either: 1. Ordering of point defects caused by vacancies in the spinel structure of maghemite, due to the removal of excess Fe3+ ions during the oxidation of magnetite, to form twins. It is in this twinning that the martitisation mechanism occurs.2. Grain boundary migration by hematite at the expense of magnetite is due to the presence of fluid along the crystal interfaces, where maghemite forms due to excess Fe3+ produced during martitisation of the magnetite, moving towards the surface of the magnetite crystals.

Within Big Bend National Park, the unconformable contact between the Buda Limestone and the overlying Boquillas Formation represents the Commanchean-Gulfian boundary. Previous studies of the geochronology of this interval have relied primarily on provincial ammonite faunas rather than foraminifera, and place the Buda and basal Boquillas in the Lower Cenomanian. Because of its indurated nature, a comprehensive foraminiferal biozonation has not been acquired for the Buda Limestone. Recent revisions to Cretaceous foraminiferal biozonations and taxonomies necessitates a new biostratigraphic study of the Buda - Boquillas interval. The overlapping ranges of F. washitensis, G. bentonensis, G. caseyi, P. appenninica, P. delrioensis, P. stephani, and R. montsalvensis place the Buda within the upper portion of the Early to Middle Cenomanian Th. globotruncanoides Zone. Microkarst found on the surface of the Buda Limestone has been interpreted as representing a subaerial exposure and sequence boundary. However, microkarst-like features can result from subaqueous or intrastratal processes. Carbon and oxygen stable isotope analysis of the lower and middle Buda has indicated a mean δ13C value of 1.73‰ VPDB, which is in line with other values reported from the Lower Cenomanian. The top 2.6m of Buda contains a 0.62‰ negative δ13C shift from 1.88‰ VPDB to 1.26‰ VDPB in a 40 cm interval, expected if subaerial exposure occurred. Higher variation in measured carbon isotope values beneath the contact also lend evidence for meteoric alteration. The standard deviation in δ13C values from the top 2.8 m of the Buda is 0.207, which is 2.16 times larger than the rest of the studied section at 0.096. The Buda contains a shallow pelagic-dominated fauna of heterohelicids (45-90%), globigerinellids (3-37%), and hedbergellids (4-22%). Intermediate-depth globigerinellids display an initial increase followed by a marked decrease in abundance upsection, interpreted as sea level transgression and regression, respectively. The lower contact of the Buda with the Del Rio Clay has been previously interpreted as a subaerial exposure, and a P:B break from ~0% planktonics in the upper Del Rio to ~80% in the Buda supports this claim. This study therefore interprets both the upper and lower contacts of the Buda as sequence boundaries. The overlying 1.2 m Boquillas is nearly devoid of benthics and represents a deeper assemblage including the double-keeled Dicarinella sp., as well as several Upper Cenomanian (D. algeriana Subzone) species. Based on foraminiferal data, the duration of the Buda - Boquillas unconformity is roughly equivalent to the missing Th. reicheli and Th. greenhornensis Biozones, or a sizable portion of the Middle Cenomanian. / Systematic paleontology -- Biostratigraphy of the Buda Limestone -- Biostratigraphy of the lowermost Boquillas Formation -- Stable isotope geochemistry. / Department of Geological Sciences

Multi-vehicle systems offer many advantages in engineering applications such as increased efficiency and robustness. However, the disadvantage of multi-vehicle systems is that they require a high level of organization and coordination in order to successfully complete a task. Formation control is a field of engineering that addresses this issue, and provides coordination schemes to successfully implement multi-vehicle systems. Two approaches to group coordination were proposed in this work: geometric and self-organizing formations. A geometric reconfiguring formation was developed using the leader-follower method, and the self-organizing formation was developed using the velocity potential equations from fluid flow theory. Both formation controllers were first tested in simulation in MATLAB, and then implemented on the X80 mobile robot units. Various experiments were conducted to test the formations under difficult obstacle scenarios. The robots successfully navigated through the obstacles as a coordinated as a team using the self-organizing and geometric formation control approaches.

The Comet Gold Mine is in the Murchison mineral field which lies within the Yilgarn Craton of Western Australia. Several different geophysical methods were used in this study to define the geophysical signatures of sedimentary iron formations (SIF) and altered basalt associated with gold mineralisation. The geophysical surveys carried out at the Comet Gold Mine were gravity, sub-audio magnetics (SAM), transient electromagnetics (TEM) and downhole geophysical logging. Data from previous geophysical surveying were also used, and these included highresolution aeromagnetics and TEMPEST airborne electromagnetics. Other exploration information, such as geology and drillhole data, were integrated with geophysical results to study the geophysical responses and generate a geophysical interpretation map. / The main aim of this study was to generate an understanding of the various geophysical responses of geology and gold mineralisation in the Comet Mine area for future gold exploration in this region. Particularly, the study focused on the ability of the SAM method to map out geology and geophysical response for gold mineralisation. The response from SAM surveying has been investigated over an area of 13 sq kms. The SAM surveying was completed using a transmitter current of 5-8 Amp with a 50% duty cycle at 4 Hz frequency, which was considered the best setting for the Comet area. The SAM anomalies were compared to results from other geophysical methods. The results of all geophysical surveying suggested that the TEM method was also effective for identifying altered sulphide and magnetic altered rock associated with gold mineralisation. / Experiments were carried out using SAM surveying with electrodes in standard surface pits and pits placed directly into the gold mineralised structure. Both surveys showed very similar results, so in this area, surface electrode pits work well for current injection during SAM surveys. The similarities are probably due to the lack of conductive regolith cover in the Comet Mine area. / The SAM response was studied for survey grids using different electrode positions and directions. Experiments in changing SAM electrode position over the same area were carried out along and across geological strike to detect the different geological structure directions. The EQMMR response was different for electrodes oriented at 90º when surveys were repeated over the same area. SAM mainly measures conductive features running sub-parallel to the electrode direction, but the EQMMIP response was mostly the same, despite the difference in electrode direction. In addition, the EQMMIP result was very similar for rotated grids, with some distortion occurring around the main EQMMR anomaly near the Venus open cut pit. Therefore, SAM chargeability was not strongly polarised along the electrode direction like the EQMMR response. This is consistent with the theory of MIP that the method detects the effect of induced polarisation in the earth by virtue of the magnetic fields associated with current flow in polarisable bodies within the earth. / Gravity data were collected along in 4 transects 500 m apart and at 50 m station spacing. 3D gravity modelling using polygonal shapes was completed to a good fit with felsic and mafic rocks by having rock units dip to the SE. Euler depth solution calculations were applied to locate contacts and deep gravity sources. Gravity surveying has also proved to be a useful survey method for geological mapping and locating regional structures. / Ground TEM survey data were used at the Venus prospect to map out conductive zones at depths ranging from 30 to 90 m. All anomaly bodies were interpreted to have a SE dip. The modelled ground TEM results were compared to TEMPEST airborne electromagnetic conductivity depth slices. Both EM survey results showed reasonably similar patterns, but the ground TEM method provided more reliable conductor locations and depth estimations that correlated well with the drilling information and downhole conductivity logging. / Geophysical logs of natural gamma and inductive conductivity were surveyed in 5 drillholes that intersected gold alteration zones. The alteration zones associated with gold mineralised sediments, sulphide and magnetic minerals were identified in the downhole logs as increased conductivity, with a sight increase in the natural gamma response. Natural gamma was usually high above a background of host rock in the gold mineralised shear zones. This was likely due to K associated with the clay rich SIF units, and sericite and biotite from gold related alteration. During this study, drillhole CTRC028 was drilled into a modelled TEM anomaly, and gold mineralised SIF was intersected at the predicted location from the model. / Geophysical survey information (magnetics, gravity, SAM and TEM) and anomalies in the Comet area were found to be primarily controlled by the local structures and mineralisation along these structures. Modelled ground TEM results were compared to TEMPEST airborne, EM data and showed reasonably similar patterns. The geophysical survey data also highlights black shale units, which can produce a false target commonly running parallel to the sulphide altered fault zones and SIF units, because of graphite and sulphide in the black shale. / The TEMPEST data were a valuable guide to bedrock conductivity over the outline project area at Comet, and the follow–up ground TEM and SAM survey data was very useful for accurately pin-pointing anomalies for drill testing. / Geophysical and geological data analysed in this study was used to generate a geophysical interpretation map at 1:5,000 scale. The new interpretation of geological units and structures at Comet will provide geologists with a better understand about the geological and structural setting for mineralisation in the Comet area. For example, the Comet Fault represents a faulted limb of the Comet fold structure that has both limbs dipping to the SE, and plunges to the NE. Magnetic anomalies associated with SIF are considered to correlate with some gold bearing horizons and the location of the Comet Fault, that has become more siliceous and altered by sulphide minerals and magnetite minerals. / It is recommended that other prospect areas in the region should be surveyed using the SAM method in order to identify shallow gold bearing structures and improve geological interpretations ahead of drilling.

[pt] O desenvolvimento e exploração das formações shale gas a nível mundial é relativamente recente, tendo seu início nos Estados Unidos no final da década 1990. A partir dos resultados obtidos com a aplicação do procedimento de fraturamento hidráulico, como método de estimulação, o estudo e avaliação de outros prospectos shale gas em outras regiões do mundo foi estimulado. No entanto, a análise, estudo e caracterização deste tipo de reservatórios são dificultados uma vez que devem ser levados em conta múltiplos fatores relacionados a geologia, mineralogia, petrofísica, geoquímica, entre outros. O fraturamento hidráulico é um processo hidromecânico acoplado com alto grau de dificuldade especialmente em reservatórios shale gas, onde existe a presença de fraturas. Um estudo numérico é conduzido neste trabalho com o objetivo de investigar o comportamento hidromecânico de uma fratura natural durante a injeção de fluido. O software UDEC (Universal Distinct Element Code) baseado no método dos elementos discretos foi empregado no desenvolvimento da modelagem numérica. O UDEC tem a capacidade de modelar o comportamento hidromecânico de uma fratura incluindo os fenômenos de abertura/fechamento das fraturas, cisalhamento e dilatação sob condições de contato ou separação. Nesta investigação numérica foram criados modelos de reservatório com fraturas naturais aleatórias por meio de uma distribuição voronoi visando representar a complexidade da rede de fraturas naturais presentes nas formações shale gas. Os resultados do estudo numérico mostram que o comportamento hidromecânico do sistema é fortemente dependente da variação de parâmetros como tensões in situ, viscosidade do fluido de fraturamento e taxa de injeção de fluido. Portanto, estes resultados proporcionam um melhor entendimento dos mecanismos de fraturamento e resposta da pressão de um tratamento de fraturamento hidráulico em um reservatório de gás não-convencional naturalmente fraturado. / [en] The development and deployment of shale gas formations around the world are relatively recent, starting in the United Stated in the late 1990. From the results obtained with the application of hydraulic fracturing as a method of stimulation, the study and evaluation of other prospects of shale gas in others places in the world was encouraged. However, the analysis, study and characterization of this type of reservoirs are difficult, because it must be taken into account several factors such as geology, mineralogy, petrophysics, geochemistry among others. Hydraulic fracturing is a complicated hydro-mechanical coupled process, with high difficulty degree especially in shale gas reservoir, where natural fractures exist. A numerical study is conducted to investigate the hydromechanical behavior of a natural fracture during fluid injection. UDEC (Universal Distinct Element Code) software based on discrete elements method was employed to numerical modeling development. UDEC has the ability to model the hydro-mechanical behavior of a fracture including phenomena like fracture enlargement, closure, slippage, and dilation under contact or separation condition. In this numerical investigation, numerical reservoir models, with random natural fractures through a distribution voronoi were created aiming to represent the network complexity of natural fractures present in shale gas formations. The numerical study results show that the hydromechanical system behavior is strongly dependent on the parameters variation such as in situ stress, fluid fracturing viscosity and fluid injection rate. Therefore, these results provide a better understanding of fracturing mechanisms and pressure response of a hydraulic fracturing treatment in a non- conventional naturally fractured reservoir.