The objective of this study is to better understand the relationship between organic compounds and carbonate mineral growth in different natural environments by imaging the interface between organic compounds and carbonate precipitates in ancient and modern rocks, and laboratory experiments. Three separate projects were designed to document the organic/carbonate mineral interface through imagery. 1) Images of the interfaces between organic components and initial mineral precipitates were investigated in a deteriorating microbial mat from Vermelha, Brazil that was taken from the site in 2006. As the mat deteriorated the amount of calcification increased. A section of the transitional section between living algae and calcitic precipitate was taken for analysis. Transmission Electron Microscopy (TEM) along with Energy-dispersive X-ray spectroscopy (X-EDS) showed carbonate minerals growing on cell walls and using dark, amorphous structures as nucleation points. X-EDS results showed that the dark amorphous structures have high concentrations of silica, magnesium, and oxygen, which appears to promote carbonate mineral precipitation. 2) Laboratory experiments were designed to precipitate calcite in solution with varying organic compounds and then use TEM analysis to image the precipitants, specifically the transitional area between the organic compounds and carbonate minerals. Calcite crystals appeared to nucleate off of the surfaces of palmitic and stearic acid. X-EDS analysis verified the elemental transition from organic matter to carbonate mineral growth. 3) Cold water, authigenic carbonate rocks collected by Dr. Adam Skarke, on July 6, 2016 during the National Oceanographic Laboratory System (UNOLS) research cruise to a methane seep off the eastern North America coast were imaged and analyzed. Scanning Electron Microscope (SEM), EDS and XRD analysis were used to better understand the sequence of events that led to formation of this unusual rock. The rock grew in situ trapping quartz and metallic minerals in aragonitic cement, and then was cut and pushed apart by veins filled with aragonitic cement in a pattern reminiscent of septarian nodules.

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Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 2003. / Typescript. Vita. Includes bibliographical references. Also available on the Internet.

Thesis (M.S.)--University of Missouri-Columbia, 2004. / Typescript. Includes bibliographical references (leaves 24-25). Also available on the Internet.

Caribbean coral reefs have undergone changes in coral cover, structural complexity and assemblage composition since the 1970s. Although some of the ecological consequences associated with these changes have been well documented, the consequences for ecosystem functions dependent on reef structure are less well understood. In particular, there has been little research into the effects of change, on carbonate production and bioerosion; both are critical controls of structural complexity. Currently, there is only a very limited understanding of how both processes vary within and between different habitat types and what this means for ecosystem functioning. Carbonate framework production and bioerosion were investigated within three habitat types (hardgrounds, Acropora palmata reef and Orbicella reef) under sheltered and exposed wave energy regimes on Grand Cayman. Census based assessments were used, allowing the identification of functionally important species. Additionally, habitat specific calcification rates were measured for calcareous encruster communities to improve estimations of carbonate production; mean rates of calcification ranged from 0.19 to 1.14 G (1G = 1 kg CaCO3 m-2 yr-1) within hardgrounds (4–7 m), Acropora palmata reef (1–8 m) and Orbicella reef habitats (8–15 m) and were significantly higher at wave exposed sites. The rates of bioerosion for two sponge species, Siphonodictyon brevitubulatum and Cliona tenuis, were also measured and new approaches to estimating excavating sponge community bioerosion were developed to improves bioerosion estimates. Mean carbonate framework production was 0.38 G within hardgrounds, 2.65 G within Acropora palmata reef habitat and 3.54 G within Orbicella reef habitat but not significantly different between wave exposure regimes. Calcareous encruster communities, dominated by coralline algae, were identified as key carbonate producers within shallow reef habitats on the exposed south coast. They may be important to the maintenance of reef structure in these degraded reef habitats. Orbicella species were the most important carbonate producers within all reef habitats. Mean total bioerosion was 1.32, 2.27 and 2.28 G within hardgrounds, Acropora palmata reef and Orbicella reef habitats respectively. 4 Total bioerosion was not significantly different between wave exposure regimes for any habitat type, but almost completely dominated by parrotfish (29–86 %). On Grand Cayman, both carbonate framework production and bioerosion were less than that measured in comparative habitats, across the Caribbean, despite the presence of a well-managed marine protected area on the sheltered west coast. The highest rates of net carbonate production occurred in the deepest habitat - Orbicella reef (exposed: +1.45 G, sheltered: +1.07 G). Sheltered and exposed Acropora palmata reef habitat had net production rates of +0.53 and +0.30 G respectively. Hardgrounds were net erosional (-0.94 G). Overall the results suggest a change in the focal point for reef accumulation on Grand Cayman that may alter geomorphology over time. Additionally, Acropora palmata reef habitats are likely to be in a state of accretionary stasis, which may have shutdown reef growth in reef crest environments as carbonate framework produced within these habitats is a major contributor to reef accumulation at the reef crest.

En domaine de plate-forme carbonatée épicontinentale peu profonde, la production sédimentaire est étroitement liée aux variations eustatiques, au climat et à la position paleogéographique. Les périodes d’émersion constituent des phases de non-dépôt durant lesquelles l’arrêt de l’enregistrement sédimentaire peut être relayé par un enregistrement diagénétique. Les transformations associées aux discontinuités (réarrangement des porosités, modifications lithologiques, circulations tardives…) peuvent avoir un rôle déterminant sur les propriétés pétrophysiques des réservoirs carbonatés. La détection des surfaces d’émersion et des produits diagénétiques associés apparaît donc essentielle pour préciser la qualité des réservoirs, par (1) la compréhension des processus sédimento-diagénétiques aux limites de séquence, (2) la comparaison de données d’affleurement et de subsurface, et la caractérisation des géométries des réservoirs associés, (3) l’analyse de l’impact de la diagenèse associée à ces surfaces (amélioration ou détérioration des propriétés réservoir).La Formation Natih d’Oman (Albien sup. – Turonien inf.) se situe au sommet d’une épaisse série de plates-formes carbonatées peu profondes et de grande extension géographique (marge de la Néotéthys). La Formation Natih est subdivisée en quatre séquences majeures (3ème ordre) constituées d’unités transgressives tabulaires à faiblement inclinées (rampe à faciès boueux) et de prismes régressifs progradants plus inclinés (barrière bioclastique bien différenicée protégeant un domaine de lagon interne) (van Buchem et al. 2002). Ces séquences se terminent par une ou plusieurs surfaces d’émersion, pouvant être associées à des incisions (Grélaud et al. 2006). La présente étude porte sur l’analyse diagénétique de ces surfaces d’émersion par l’intégration de données de terrain (Foothills d’Adam, Jebel Akhdar) et de subsurface (carottes de forage et données de puits de champs pétroliers voisins).L’analyse diagénétique détaillée des affleurements et des données de subsurface repose sur l’étude de la chronologie relative et de la répartition spatiale des phases diagénétiques associées aux surfaces d’émersion. Elle démontre la mise en place d’une diagenèse précoce dans des conditions relativement arides qui se traduisent par l’absence de karstification et de phénomènes pédogénétiques bien développés sur la plate-forme émergée. Sous les surfaces, des circulations de fluides météoriques oxydants, alimentés par des recharges latérales, entrainent une dissolution précoce des minéralogies instables et la précipitation de ciments météoriques en domaine phréatique. Cette étude diagénétique est complétée par l’analyse des phases mésogétiques et télogénétiques qui permettent de contraindre la séquence diagénétique de la Formation Natih avec les grandes étapes de déformations tectoniques et d’enfouissement.A partir de ces résultats, les produits diagénétiques et leur impact sur l’évolution des réservoirs peuvent être caractérisés et interprétés pour chaque surface. Ils résultent d'interactions complexes entre des facteurs intrinsèques et extrinsèques comme la dynamique de l'aquifère météorique, le contexte paléogéographique et géodynamique au moment des émersions, la maturité du substrat... Ces paramètres sont effectifs au moment du dépôt et des émersions. Toutefois la préservation des produits éogénétiques peut-être fortement influencée par l'évolution au cours de l'enfouissement qui se caractérise par des phénomènes de compaction, cimentation ou dissolution. / On epeiric carbonate platforms, sediment production and stratigraphic architecture are mainly controlled by sea-level variations, climate and palaeogeographic position. During periods of subaerial exposure, carbonate production/deposition stops and the sedimentary record can then be replaced by the diagenetic record. The diagenetic transformations associated to discontinuity surfaces (rearrangement of porosity distribution, lithological alteration, late fluid circulation …) may have a significant impact on carbonate reservoir properties. The characterization of subaerial exposure surfaces and associated diagenesis is therefore essential to understand and predict reservoir quality. It requires: (1) the study of the sedimentological and diagenetic processes at the sequence boundaries, (2) the integration and comparison of outcrop and subsurface data, including respective reservoir architecture, (3) the analysis of the diagenetic overprint related to these surfaces (enhancement or deterioration of reservoir properties).The Natih Formation (Late Albian – Early Turonian) is the last of a thick succession of Cretaceous epeiric carbonate platforms. It is subdivided into four third-order sequences. In each sequence, the transgressive phase is formed by flat to slightly sloping units (muddy ramp facies) whereas the regressive phase corresponds to a higher angle prograding carbonate ramp with a well developed bioclastic margin protecting an inner lagoon (van Buchem et al. 2002). These sequences are capped by one or several subaerial exposure surfaces, sometimes associated with incisions (Grélaud et al. 2006). The present study focuses on the diagenetic analysis of these emersion surfaces by the integration of outcrop (Adam Foothills, Jabal Akhdar) and subsurface data (neighbouring oil fields from the interior Oman).The detailed study of the lateral distribution and chronology of the diagenetic phases associated with emersion surfaces form the basis for the sedimentological and diagenetic model. The results highlight the development of a meteoric diagenetic system which was probably subject to relatively arid conditions, explaining the absence of karstification and pedogenetic features on the exposed platform. Below the emersion surfaces, the circulation of oxidizing meteoric fluids, laterally sourced, leads to the early dissolution of unstable minerals and the precipitation of meteoric cements in the phreatic domain.This diagenetic study is completed by the analysis of the mesogenetic and telogenetic phases, which allow to constrain the diagenetic sequence in relation with the main phases of deformation and burial of the Natih Formation.These results show the particularities of each subaerial exposure event in terms of diagenetic products and their impact on reservoir properties. They result from complex interrelations between external and intrinsic factors, such as the dynamics of meteoric aquifers, the geodynamic and paleogeographic context during exposure, chemical reactivity ... These are effective during deposition and subaerial exposure. However, the preservation of exposure-related diagenetic features may subsequently be influenced by burial evolution trough competition between compaction, cementation and dissolution.

Les études menées au cours de cette thèse portent sur le développement de différents traitements du bois basés sur l'utilisation de carbonates cycliques dérivés du glycérol, matière première d'origine renouvelables, dans le but de développer de nouvelles méthodes de modification chimiques du matériau bois. Les travaux se sont déroulés en deux temps: la première partie du travail a consisté à utiliser directement le carbonate de glycérol pour développer des traitements en phase aqueuse suivis, après imprégnation du produit dans le bois, d'une réaction de polymérisation permettant de fixer ce dernier afin d'éviter son lessivage. Les résultats obtenus se sont avérés difficilement applicables en raison des conditions réactionnelles trop dures, incompatibles avec la stabilité thermique du bois. La seconde partie a concerné la formation de polyuréthanes dans le bois sans avoir recours à l'utilisation d'isocyanates en utilisant des réactions de condensation d'amines sur des di ou polycarbonates cycliques. Différentes voies ont été explorées pour l'élaboration des di ou polycarbonates cycliques impliquant soit l'utilisation du carbonate de glycérol sur un module de jonction approprié, soit l'action du carbonate de diméthyle sur du polyglycérol. La formation des polyuréthanes a ensuite été étudiée en phase homogène puis appliquée au traitement du bois. Les résultats obtenus indiquent, en fonction des traitements réalisés, une augmentation de la stabilité dimensionnelle et de la résistance du bois au champignon de pourriture brune Poria placenta. / The studies conducted during this thesis focuses on the development of various wood treatments based on the use of cyclic carbonates derived from glycerol, renewable source of raw materials in order to develop new methods of chemical modification of wood materials. The work proceeded in two stages: the first part of this work was to directly use the glycerol carbonate to develop treatments in the aqueous phase followed, after impregnating the wood product, a polymerization reaction for fixing the last to avoid leaching. The results have proved difficult to apply because of the reaction conditions too harsh, inconsistent with the thermal stability of wood. The second part related to the formation of polyurethanes in the wood without resorting to the use of isocyanates using condensation reactions of amines on cyclic di or polycarbonates. Various ways have been explored for the development of cyclic di or polycarbonate involving either the use of glycerol carbonate in a suitable junction module, or the action of dimethyl carbonate of polyglycerol. The formation of polyurethanes has been studied in a homogeneous phase and then applied to the treatment of wood. The results indicate, for the treatments performed, an increase of dimensional stability and resistance to wood brown rot fungus Poria placenta.

No / Calcium and magnesium carbonates are important minerals found in sedimentary environments. Although sandstones are the most common rock colonized by endolith organisms, the production of calcium and magnesium carbonates is important in survival strategies of organisms and as a source for the removal of oxalate ions. Extremophile organisms in some situations may convert or destroy carbonates of calcium and magnesium, which gives important information about the conditions under which these organisms can survive. The identification on the surface of Mars of 'White Rock' formations, in Juventae Chasma or Sabaea Terra, as possibly carbonate rocks makes the study of these minerals a prerequisite of remote Martian exploration. Here, we show the protocol for the identification by Raman spectroscopy of different calcium and magnesium carbonates and we present a database of relevance in the search for life, extinct or extant, on Mars; this will be useful for the assessment of data obtained from remote, miniaturized Raman spectrometers now proposed for Mars exploration.