The Stuart Oil Shale Deposit is a major oil shale resource located near Gladstone on the central Queensland coast. It contains an estimated 3.0 billion barrels of oil in place in 5.6 billion tonnes of shale. Commissioning of a plant capable of producing 4,500 barrels per day has recently commenced. The shale is preserved in Tertiary age sediments of The Narrows Beds in the southern part of The Narrows Graben. The oil shale sequence consists of repetitive cycles composed of oil shale, claystone and lesser carbonaceous oil shale in the 400 metre thick Rundle Formation. The formation is the main oil-shale bearing unit in the preserved half-graben sequence up to 1,000 metres thick. Previous studies on the lacustrine sedimentology of the Rundle Oil Shale Deposit in the northern part of The Narrows Graben have recognised eight facies that exhibit unique and recognisable cycles. The cycles and sequence for the Kerosene Creek Member of the Rundle Formation is correlatable between the Rundle and Stuart deposits. The nature of these facies and the cycles is reviewed in some detail. In conjunction with the principles of sequence stratigraphy, the ideal oil shale cycle is described as the equivalent of a parasequence within a lacustrine system. The lacustrine parasequence is bounded by lacustrine flooding surfaces. The organic material in the oil shale consists of both Type I (algal dominated) and Type III (higher plant matter dominated) kerogen. Where Type I kerogen dominate, oil yields greater than about 100 litres per tonne are common. In contrast where Type III kerogens are dominant, yields above 100 litres per tonne are rare. The variation in oil yield is described for the Stuart lacustrine system. The variation is consequent on the balance between production, preservation and degradation of the kerogen in the parasequences within systems tracts. A system for the recognition of oil shale deposition in terms of lacustrine systems tracts is established based on oil yield assay parameters and the assay oil specific gravity. The oil yield and oil specific gravity variation within the Rundle Formation is modelled by member and the nature and distribution of oil yield quality parameters in terms of the contribution of organic and inorganic source material are described. The presence of significant oil yield (greater than 50 litres per tonne) is dependent on the dominance of lacustrine transitional systems tracts and to a lesser extent, lacustrine highstand systems tracts within the parasequence sets deposited in a balanced lake system in a generally warm wet climate during the middle to late Tertiary.

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Une étude de caractérisation intégrée de pétrographie et géochimie organique a été réalisée dans les bassins de Sabinas et Chihuahua au Nord-Est du Mexique. Ces informations ont permis une modélisation numérique de la formation du gaz en considérant la subsidence thermique des charbons et des shales à gaz. Les objectifs de cette thèse sont les suivants: mise en place d'une méthodologie de caractérisation des roches étudiées ; estimation du potentiel générateur de gaz et sa distribution régionale ; estimation des ressources en gaz méthane. Les analyses effectuées sur l'ensemble des échantillons ont permis de caractériser la roche, les kérogènes, les huiles et les gaz. La méthodologie utilisée permet de croiser les informations pétrographiques et géochimiques pour pouvoir analyser le système pétrolier par modélisation numérique. Les analyses réalisées sont: réflectance% Ro, analyse élémentaire et immédiate, Rock Eval6 ® (Bulk Rock), [delta]13C, [delta]D, (gaz de charbon), microscopie électronique à balayage, analyse d'images, analyse des macéraux et inclusions fluides. Un programme informatique a été construit afin de croiser l'information des analyses des échantillons avec celle des expériences de maturation artificielle en laboratoire. Cette démarche nous à permis d'estimer les ressources en gaz méthane à la fois généré par les charbons et les shales gaz. La méthodologie utilisée pour l'étude des kérogènes et des gaz dans les deux bassins est à notre avis la plus appropriée pour répondre aux objectifs proposés dans ce travail de thèse. Celle-ci permet de caractériser l'évolution thermique des charbons, shales gas (gaz de schiste), et roches mères pétrolières / This comprehensive characterization study was performed using organic petrology and geochemistry conducted in the Sabinas basin and Chihuahua in northern Mexico. This information allowed a numerical modeling of gas formation, considering the thermal subsidence of coal and carbonaceous shales.The objectives of this thesis are: establish a characterization methodology for the studied rocks ; estimate potential gas generator and its regional distribution ; estimate the methane gas resources. For the development of this project, we conducted an intensive campaign representative sampling of coal, carbonaceous shales and coal gas "in situ". For the Sabinas basin were studied 97 samples and 114 samples in the basin of Chihuahua. The analyses carried out that were used on the samples analyzed allowed to characterize the kerogen and gas. The methodology used to cross petrographic and geochemical information to analyze the petroleum system by numerical modeling. Analyses were: Petrographic, reflectance %Ro, elemental analysis and immediate, Rock Eval6 ® (Bulk rock), isotopic analysis, [delta]13C, [delta]D, (coal gas), scanning electron microscopy, image analysis and analysis of macerals fluid inclusions. The analyzes that were used on the samples allowed to characterize the sample, the kerogen and gas. The methodology used to cross petrographic and geochemical information for analyze the oil system by numerical modeling. Analyses were: Petrographic, reflectance% Ro, elemental analysis and immediate, Rock Eval6 ® (Bulk rock), isotopic analysis, d13C, dD, (coal gas), scanning electron microscopy, image analysis and analysis of macerals fluid inclusions. A computer program was constructed to cross the information with the analysis of samples of artificial maturation experiments in the laboratory. This approach allowed estimation of methane gas resources generated by coal and carbonaceous shales. [...] In conclusion, between the two basins studied, the Sabinas basin, generates more gas for industrial exploitation. However, the rocks of the basin of Chihuahua unconventional types (shale gas) show good potential for hydrocarbon generation. The methodology used for the study of kerogen and gas in the two basins is in our opinion the most appropriate to meet the objectives proposed in this thesis. This allows to characterize the thermal evolution of coal, carbonaceous shale (shale gas), coal gas and hydrocarbon source rocks

Soil organic matter (SOM) is highly important for soil quality and the global carbon cycle. SOM content is influenced by a complex interplay of many different factors such as time, climate, parent material, vegetation, and others. The effect of time is often studied using the chronosequence approach using a set of study sites differing in age but comparable in other soil-forming factors. The effect of other factors can be studied by comparing two or more chronosequences. An important assumption of these approaches is that the SOM quantification methods produce comparable results both among sites of each sequence and among different sequences. In this thesis, I explored the key factors in SOM accumulation and dealt with SOM quantification methods. I studied SOM accumulation in two model situations - in post-mining sites after open-cast coal and oil shale mining and in landslides in the Western Carpathians. The results of this thesis are summarized in one book chapter accepted for publication and four papers, out of which three have been published and one is prepared for publication in an international journal with impact factor. The key factor affecting the rate of SOM accumulation after a major disturbance is time. The accumulation rates found in the first 40 to 100 years in both post-mining sites...

Nas últimas décadas, os Lagerstätten estiveram no centro das discussões relativas à história paleobiológica e geológica da Terra. Em particular, o Membro Crato da Formação Santana (Bacia do Araripe, Nordeste do Brasil) é um dos mais significantes Lagerstätten do Cretáceo já que registra invertebrados, vertebrados e plantas excepcionalmente preservados em sedimentos carbonáticos de um palaeolago. O principal objetivo desta dissertação é lançar luz sobre os processos de preservação responsáveis pela fossilização de insetos e peixes com tecidos moles em 3D. Lâminas petrográficas e diversas técnicas paleométricas - micro-Espectroscopia Raman, Fluorescência de raios-X (FRX) convencional, micro-FRX com fonte de luz sincrotron (RS-µFRX), emissão de Raios-X induzida por partículas (PIXE), microscopia eletrônica de varredura (MEV) e espectroscopia de energia dispersiva de Raios-X (EDS) - foram empregadas para caracterizar a rocha matriz, a morfologia e fidelidade de preservação dos tecidos moles e as composições elementares e moleculares dos fósseis em escala de centímetros e mícron. Os resultados revelam que, enquanto insetos e tecidos moles de peixes encontrados nos denominados calcários beges (BL) são substituídos por pseudomorfos de pirita framboidal (após oxidação da pirita), os quais ocorrem juntamente com possíveis substâncias poliméricas extracelulares secretadas por bactérias (EPS), tecidos de peixes dos calcários cinza (GL) são querogenizados. Em insetos, existe variação de tamanho dos framboides para dentro dos fósseis, que é aqui interpretada como produto do equilíbrio entre as taxas de difusão e de nucleação dos minerais. Além disso, a distribuição preferencial de Zn e Cu em estruturas piritizadas de insetos e peixes em comparação com a sua matriz é aqui considerada como sendo o resultado da fixação de elementos químicos em biofilmes bacterianos. Zn concentrado nos ossos de peixes com querogenizados e Fe/Cu observados em seus tecidos moles são considerados como tendo sido incorporados durante a vida dos peixes. No caso particular de peixes, modelo originalmente proposto para a preservação de metazoários do Pré-cambriano é aqui aplicado para explicar a variação de fossilização entre as fácies BL e GL. Lâminas petrográficas revelam que os GL têm geralmente teor de argila/matéria orgânica maior do que os BL, implicando que as taxas de soterramento poderiam ter sido mais intensas nos GL. Isto teria colocado carcaças em decomposição mais rapidamente na zona sedimentar de metanogênese, sendo formado o querogênio. Por outro lado, carcaças depositadas na fácies BL poderiam ter passado período mais longo na zona de redução de sulfato, o que teria levado à piritização generalizada. Além disso, a baixa porosidade do microespato, o cimento e a argila poderiam ter diminuído a migração de aceptores de elétrons dos processos de respiração bacteriana anaeróbia - particularmente redução de sulfato (RS) e metanogênese - e de seus produtos biogeoquímicos, estreitando a zona de RS, o que teria reduzido a influência da piritização em alguns níveis. Enquanto que a piritização resultou na preservação de fibras musculares em 3D, sarcolema, possíveis núcleos celulares, tendões e olhos, a querogenização preservou tecidos conjuntivos, tegumento e fibras musculares distorcidas e compactadas. Em conclusão, é aqui proposto que fácies influenciadas por processos paleoambientais e geobiológicos produziram fósseis com gradiente diferencial de fidelidade de preservação de acordo com cada via tafonômica seguida. / Over the past decades, the so-called Fossil Lagerstätten have been in the core of discussions concerning the palaeobiological and geological history of the Earth. In particular, the Crato Member from the Santana Formation (Araripe Basin, north-east Brazil) is one of the most significant Cretaceous Lagerstätten since it records exceptionally well-preserved fossil invertebrates, vertebrates, and plants, deposited in palaeolake carbonate beds. The main aim of this dissertation is to shed light on the preservational processes responsible for the fossilization of insects and fishes still retaining 3D soft tissues. Petrographic thin sections and several palaeometric techniques - micro-Raman Spectroscopy, conventional X-ray Fluorescence (XRF), Synchrotron micro-XRF (SR-µXRF), Particle-Induced X-ray Emission (PIXE), Scanning Electron Microscopy (SEM), and Energy-Dispersive X-ray Spectroscopy (EDS) - have been employed to characterize the host rock, soft-tissue morphology and preservational fidelity, and fossil elemental and molecular compositions in centimetre to micrometre scale. The results reveal that while insects and fish soft-tissues found in the so called beige limestones (BL) are replaced by framboidal pyrite pseudomorphs (after pyrite oxidation) occurring together with putative bacterially-secreted extracellular polymeric substances (EPS), labile tissues of fishes from the grey limestones (GL) are kerogenized. In insects, there is a variation of framboid size inward the fossils, which is here interpreted as a product of the balance between diffusion and mineral nucleation rates. Moreover, the preferential distribution of Zn and Cu in pyritized insect/fish labile structures in comparison to their rock matrix is here considered as being the result of element fixation in bacterial biofilms. Zn concentrated in bones of kerogenized fishes and Fe/Cu occurring in their soft tissues are considered to have been incorporated during fish life. In the particular case of fishes, a model originally proposed for metazoan preservation in the Precambrian is here applied to explain the variation of fossilization between the BL and GL facies. Petrographic thin sections reveal that GL have generally higher clay/organic matter contents than BL, thus implying that burial rates might have been more intense in the former. This could have placed decaying carcasses more quickly in the methanogenesis sedimentary zone, in that way being kerogenized. On the other hand, carcasses deposited in the BL facies could have spent a longer period in the sulphate-reduction zone, which would have accounted for pervasive pyritization. Additionally, microspar low porosity, cement and clay could have diminished both downward migrations of electron acceptors for anaerobic bacterial respiration processes - particularly sulphate-reduction (SR) and methanogenesis - and of their biogeochemical products, narrowing the SR zone, which would have lowered the impact of pyritization in some levels. While pyritization has recorded 3D muscle fibres, sarcolemma, putative cell nuclei, tendons and eyes, kerogenization has yielded connective tissues, integument and compressed/distorted muscle fibres. In conclusion, it is here proposed that palaeoenvironmental/geobiological-influenced facies have yielded fossils with a variable preservational-fidelity gradient, accordingly to each taphonomic pathway followed.

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No description available.

Pétrole et gaz proviennent de la décomposition de la matière organique dans la croûte terrestre. En s’enfouissant, les résidus organiques se décomposent en un solide poreux et carboné, appelé kérogène et en un fluide composé d’hydrocarbures et de petites molécules telles que de l’eau. Le processus de formation du kérogène n’est pas totalement élucidé et une modélisation aiderait à une meilleure compréhension à la fois de sa structure et de sa composition et serait utile à l’industrie pétrolière.Dans le présent travail, nous adoptons une approche thermodynamique ayant pour but, à l’aide de simulations numériques, de d’étudier la décomposition de précurseurs de kérogène d’un type donné –ici le type III- dans les conditions d’un réservoir géologique. La méthode dite de Replica Exchange Molecular Dynamics (REMD) est appliquée pour étudier la décomposition de cristaux de cellulose et de lignine. Le potentiel d’interaction ReaxFF et le code LAMMPS sont utilisés. La REMD est une façon de surmonter de larges barrières d’énergie libre, en améliorant l’échantillonnage de configurations d’une dynamique moléculaire conventionnelle à température constante, en utilisant des états générés à températures supérieures.En fin de simulation, les systèmes ont atteint un état d’équilibre entre deux phases : une phase riche en carbone, composée d’amas de macromolécules, que nous appelons « solide » et d’une phase riche en oxygène et en hydrogène, composée de petites molécules, que nous dénommons « fluide ». L’évolution des parties solides de nos systèmes coïncide avec celle d’échantillons naturels de kérogènes de type III. / In deep underground, organic residues decompose into a carbonaceous porous solid, called kerogen and a fluid usually composed of hydrocarbons and other small molecules such as water, carbon monoxide. The formation process of the kerogen remains poorly understood. Modeling its geological maturation could widen the understanding of both structure and composition of kerogen, and could be useful to oil and gas industry.In this work we adopt a purely thermodynamic approach in which we aim, through molecular simulations, at determining the thermodynamic equilibrium corresponding to the decomposition of given organic precursors of a specific type of kerogen –namely type III- under reservoir conditions. Starting from cellulose and lignin crystal structures we use replica exchange molecular dynamics (REMD) simulations, using the reactive force field ReaxFF and the open-source code LAMMPS. The REMD method is a way ofovercoming large free energy barriers, by enhancing the configurational sampling of a conventional constant temperature MD using states from higher temperatures.At the end of the simulations, we have reached for both systems, a stage where they can clearly be cast into two phases: a carbon-rich phase made of large molecular clusters that we call here the "solid" phase, and a oxygen and hydrogen rich phase made of small molecules that we call "fluid" phase.The evolution of solid parts for both systems and the natural evolution of a type III kerogen clearly match. Evolution of our systems follows the one of natural samples, as well as the one of a type III kerogen submitted to an experimental confined pyrolysis.