This study focuses on the facies changes from the lower slope to toe-of-slope to basin floor over a 10 km outcrop belt, in down-dip and oblique-strike directions to the basin margin. The Jurassic Los Molles Formation in Neuquen Basin, Argentina represents the slope and basin floor of basin margin clinoforms, coeval with the shallow water and fluvial deposits named Las Lajas and Challaco formations respectively. The shallow and deep water deposits are diachronously linked in an Early-Mid Jurassic source-to-sink system developed in a back-arc basin during the incipient development of the Andes Mountains. Satellite images, high resolution panorama pictures and measured sections were used to correlate and interpret the spatial variability and overall geometry of the base of slope to basin floor units. The observations of this study refine the model for the channel-to-lobe transition zone with increase recognition and quantification of facies and architecture variability. The Los Molles basin margin was coarse grained and was ideal to observe changes in the geometry and depositional facies of channel-to-lobe deposits from updip to downdip continuous over an 8 km outcrop belt. The described channel-to-lobe transition zone clearly shows a downdip change in bed boundaries from dominantly erosive to non-erosional (bypass) to depositional and with a range of distinct facies changes. In the transition zone the sand to shale ratio is high (N:G: 65-70 %), with gutter casts and deep scours, with a high degree of amalgamation, gravel lags, mud rip-up clasts and laterally migrating beds. Within the same depositional unit (deep water lobe), at the base of the slope, the dominant sandstone beds change from amalgamated structureless and normal graded sandstone beds in the channelized lobe axis to parallel laminated and normally graded in the channelized lobe off-axis areas. Similar facies changes have been observed along proximal to distal direction. The lateral change of the dominant structures in the beds indicates changes in the flow regime and depositional style. / text

This work is focused on characterising and evaluating the intensity and selectivity of the marine fauna during the Tr/J mass extinction and recovery of the ecosystem in different localities throughout Pangaea. To address this, four localities were studied: St. Audrie’s Bay, Larne and Pinhay Bay in the UK, and Portezuelo Providencia in Chile. From each locality, samples were taken at approximately 1m intervals throughout the Tr/J sections. Species abundance per sample was estimated and each species was classified according to autoecological information derived from the literature. In order to assess changes in the structure and composition of the assemblages, NMDS and beta diversity index were performed, dominance and richness were estimated and the data were tested against five rank abundance (RAD) models. Ecospace modelling was used to estimate the loss in ecological diversity. Measures of the body size of bivalves and ichno-parameters were recorded on each section. Through the UK sections, the richness, dominance and the composition rate shifted abruptly during the extinction event. A geometric model shows the best fit during extinction events and, in contrast, a log-normal model best fits the pre-extinction and recovery event. The body size of the bivalves did not decrease during the Tr/J, while the coverage, richness and body size of ichnofossils increased during the recovery. The Chile Tr/J section records low richness, but the ecological complexity and richness decreases through the interval and composition records high turnover, while the dominance increases. The results indicate that the Tr/J disruption changed species composition in a relatively short time period, which decreased the ecological functionality of the invertebrate marine assemblage. In spatial terms, the UK fauna show a clear response to the extinction effect, but the diversity response of the Chilean assemblage is not clear at all, which may be related to taphonomical bias. Alternatively, this work analysed stage-by-stage occupation of ecospace of 3181 genera recorded from Sepkoski`s compendium for the marine fauna from the Late Permian to Early Jurassic. The ecospace can be represented as a combination of the three axes of tiering, motility and feeding, each divided into six subcategories. From the Cambrian to Recent, ecospace utilisation has tripled, however the trend through the Phanerozoic remains unclear. This result indicates that from the Guadalupian to Sinemurian the number of modes of life did not increase significantly, but the ecospace packing does. There was a significant positive correlation between abundance of predators and both infaunalisation and motility. However, the ecospace utilisation decreased 35% and 16% at the end of Permian and Triassic, respectively. During the extinction events, non-motile animals, organisms with little physiological control of biocalcification and the epifaunal forms, were heavily affected. This indicates that the mass extinction had a particular ecological effect on the biota and is an important episode of ecological changes due to ecological selectivity. Parallel, the appearance of adaptations to new trophic niches during the Triassic, like durophagy, presumably increased predation pressure and drove the increase in benthic infaunalisation. This series of adaptation could be potentially associated with the Marine Mesozoic Revolution.

Les coccolithophoridés sont des algues marines photosynthétiques et planctoniques qui produisent des plaques micrométriques de carbonate de calcium (CaCO3) appelés coccolithes. Ces algues sont apparues il y 210 Ma et produisent actuellement la majeure partie du CaCO3 dans les océans modernes, jouant ainsi un rôle majeur dans le cycle du carbone. Cependant, l’émergence de la production de CaCO3 océanique par les coccolithophoridés au cours du Jurassique, ainsi que son impact sur le cycle du carbone, restent très mal compris. Cette étude s’est donc focalisée sur une période du Jurassique Moyen (Bajocien inférieur, -170 Ma) enregistrant la diversification de Watznaueria, un genre de coccolithophoridé qui a ensuite dominé la production de CaCO3 océanique pendant plus de 80 Ma. L’analyse des assemblages de coccolithes du Jurassique Moyen du Portugal et du sud de la France, réalisée à l’aide d’une méthode de reconnaissance automatique appliquée pour la première fois aux coccolithes du Jurassique, a permis de quantifier l’importance de cette période de diversification sur la production de CaCO3 pélagique. En outre, la durée de cet intervalle clé a été réévaluée grâce à l’analyse cyclostratigraphique des séries sédimentaires du Sud de la France. Les variations de production de CaCO3 pélagique ainsi reconstituées ont été comparées aux perturbations du cycle du carbone enregistrées par les rapports des isotopes du carbone, et indiquent un lien probable avec une augmentation marquée de la fertilité des océans. Par ailleurs, l’analyse paléontologique montre que cette diversification correspond à l’apparition successive de différentes espèces vraisemblablement opportunistes du genre Watznaueria. Enfin, les flux obtenus de CaCO3 pélagiques, largement inférieurs à ceux observés dans les océans actuels, semblent insuffisants pour avoir eu une influence significative sur le cycle global du carbone du Jurassique Moyen. / Coccolithophorids are photosynthetic and planktonic marine algae that produce micrometric calcium carbonate (CaCO3) platelets called coccoliths. These algae appeared about 210 Ma ago and produce today most of the CaCO3 in the modern oceans, hence playing a major role in the carbon cycle. Nevertheless, the onset of oceanic CaCO3 production by these organisms during the Jurassic and its impact on carbon cycling remain poorly understood. This study therefore focused on the Middle Jurassic interval (Early Bajocian, -170 Ma) which records the diversification of Watznaueria, an evolutionary important coccolith genus that subsequently dominated oceanic CaCO3 production for more than 80 Myr. The analysis of coccolith assemblages from the Middle Jurassic of southern France and Portugal, based on an automaticcoccolith recognition device used for the first time on Jurassic coccoliths, allowed quantifying the impact of this diversification on CaCO3 production. In addition, the duration of this key interval has been revaluated by the cyclostratigraphic analysis of sedimentary strata from southern France. The reconstructed changes in CaCO3 production were compared to carbon cycle perturbations recorded by carbon isotope ratios and indicate a probable link with a marked increase of ocean fertility. Besides, paleontological analyses show that this diversification episode correspond to the successive appearance of different, probably opportunistic Watznaueria species. The obtained fluxes of pelagic CaCO3 production, by far lower than those recorded in modern oceans, seems too low to have significantly impacted theMiddle Jurassic carbon cycle.

La géologie du bloc de Chine du Sud se caractérise par un important magmatisme mésozoïque dont la genèse des magmas, la mise en place des plutons et les contextes tectoniques et géodynamiques restent très disputés. Dans ce travail, 41 plutons d'âge Jurassique ont été visités. Ceux de Qitianling et Shibei ont été choisis pour des études détaillés. Les textures des granites sont magmatiques et dépourvues de déformation post-solidus. La modélisation gravimétrique révèle que le pluton de Qitianling est un lopolithe mis en place dans l'interface que représente la discordance dévonienne. Le pluton de Shibei est formé par accrétion de dykes le long d'une faille verticale. Les mesures des fabriques dans différents plutons montrent que la tectonique régionale ne contrôle pas leur mise en place. La mise en place du magma est contrôlée par sa viscosité et des structures héritées. L'étude paléomagnétique de deux plutons du même âge indique des mouvements relatifs ce qui implique que ce bloc ne peut pas être considéré comme rigide. Nos résultats montrent que le Jurassique était une époque de calme tectonique dans le secteur d'étude. Ces granites sont issus de la fusion de la croûte inférieure. Au Trias, les événements tectoniques qui ont épaissi la croûte continentale sont responsables du magmatisme jurassique. L'important contraste de rigidité du bloc de Chine du Sud est responsable de la localisation de la déformation dans sa partie SE. L'épaississement crustal contribue aussi à élever le flux de chaleur mais les magmas issus du manteau sont rares. Ainsi, les modèles de subduction océanique ou de rifting continental ne s'accordent pas avec nos résultats. / The Mesozoic geology of the South China Block (SCB) is marked by widespread magmatism. Disputes exist on magma genesis, tectonic and geodynamic contexts. The tectonic setting of the Jurassic magmatism is poorly investigated. 41 Jurassic plutons were investigated and the Qitianling and Shibei plutons were selected for detailed studies. Our study shows that the emplacement of J plutons is not related to regional tectonics. The granite textures are magmatic, devoid of post-solidus deformation. The magma emplacement is controlled by its buoyancy and the inherited structures or stratigraphic interfaces of country rocks. Gravity modeling reveals that the Qitianling pluton is a lopolith intruded in the stratigraphic uniformity and the Shibei pluton formed by dike-accretion intruded in a vertical tectonic structure. The fabric measurements on different Jurassic plutons show that the regional tectonics do not control their emplacement. Paleomagnetic results from the two contemporaneous plutons show a relative movement, implying that this block cannot be considered as a rigid one. Our results show that the Jurassic was a tectonically quiet epoch in our study area. There granites are mainly derived from partial melting of lower crust. The Triassic subduction-collison events that have trickened the continental crust are responsible for the Jurassic magmatism. Due to the high rigidity contrast of the SCB, the deformation was localized on its SE part. The crustal thickening may increase the thermal contribution of the mantle, but few mantle materials are observed. So, the slab subduction or intracontinental rifting models are not supported by our studies.

Cette thèse porte sur la Néolithisation du Nord-Ouest de la France, abordée à travers l’analyse des industries en silex jurassiques de Normandie. Objet de plusieurs influences environnementales et culturelles, cette région essentielle pour comprendre les dynamiques et les comportements socio-économiques de la Néolithisation de l’Ouest se caractérise par un environnement géologique riche en silex d’excellente qualité exploités durant toute la Préhistoire, utilisés ici comme marqueurs de ces comportements et de leur évolution sur la longue durée. L’objectif est de caractériser les productions liées à ces ressources et leur diffusion, de préciser les contextes chronoculturels dans lesquels elles évoluent, en prenant en compte tous les processus de la chaîne opératoire, depuis l’acquisition des matériaux jusqu’à l’abandon des outils. Restituer une vision cohérente de ces processus suppose un protocole qui croise les approches typo-morphologique, technologique et fonctionnelle des industries pour respecter le lien structurel qui existe entre l’économie des matières premières, la gestion des productions et de l’outillage. L’étude sur la longue durée de l’utilisation d’un type de ressources particulières offre un point de vue spécifique sur la Néolithisation de l’Ouest. Les continuités et les ruptures, la permanence ou la disparition de chaînes opératoires, procédés techniques, ou voies de distribution restituent un pan de l’évolution technique et culturelle de ces sociétés néolithiques. L’analyse critique des sites a permis de dépasser l’hétérogénéité de la documentation pour parvenir à ce but. / This thesis addresses the question of the Neolithisation of the Northwest of France, throught the analysis of the industries based on Jurassic flint from the Neolithic sequence in Normandy. Subject of several environmental and cultural influences, this region is essential for understanding the dynamics and socio-economic behaviors in the Neolithisation process. Normandy is characterized by a geological environment with excellent flint sources used throughout Prehistory, used here as markers of these behaviors and their evolution over the long term. The aim is to characterize the productions related to these sources and their distribution, the chronological and cultural sequence in which they operate, taking into account all the processes of chaîne opératoire, from flints procurement to the abandonment contexts. Restore a coherent vision of the process involves a protocol that melts typo-morphological, functional and technological approaches, to meet the structural link between the economies of raw materials, production and tools management. The study on the long-term use of a particular type of resource gives a specific point of view about Neolithisation of the Northwest of France. Continuities and ruptures, permanence or extinction of chaînes opératoires, technical processes and distribution channels restore a piece of technical evolution and cultural significance of the Neolithic societies.

The Late Rhaetian (Late Triassic) extinction event is characterised by shelled species showing a reduction in size, and thickness, which together with changed mineralogy is thought to be as a result of increased atmospheric pCO2 levels. Similar morphological changes have been demonstrated for extant species exposed experimentally to high CO2 leading to the hypothesis that Late Triassic extinctions were linked with global ocean acidification and increased oceanic palaeotemperatures. Consequently, the aim of this present work was to test this ocean acidification hypothesis by investigating morphological changes in selected shelled fossil species across this extinction event, and attempt to correlate them with changes in environmental temperature and pCO2. The abundance, size, shell thickness and mineralogy was determined for three common species, the bivalves Liostrea hisingeri and Plagiostoma gigantea and the ostracod Ogmoconchella aspinata collected from Triassic and Jurassic rocks from two locations in southwest England. Palaeotemperature was reconstructed from examination of these fossils and from the literature and atmospheric pCO2 estimated from published accounts. The shell size of bivalves increased during periods of high pCO2 and high palaeotemperature at both locations. Ostracod carapace sizes increased at St Audrie’s Bay but decreased at Lyme Regis during periods of high pCO2, while ostracod carapace size decreased during periods of high palaeotemperature at St Audrie’s Bay. However, ostracod shell thickness increased and decreased as pCO2 increased but shows no relationship with palaeotemperature at either location. Laboratory experiments on the effect of elevated pCO2 and elevated temperature on three modern species of ostracod was carried out. Modern species Leptocythere sp. and L. castanea subjected to either elevated pCO2 or elevated temperature showed increased dissolution, however size and thickness did not significantly change. In the same experimental conditions L. lacertosa showed increased dissolution however size continued to increase, while thickness was maintained. Comparison of fossil bivalve and ostracod data to modern high pCO2 and high temperature experiments illustrates some correlations to the modern experiments results indicating high pCO2 and high palaeotemperature conditions could have been occurring during the Triassic-Jurassic boundary interval. From the evidence presented, combined with an appropriate trigger (CAMP volcanism), it can be concluded that both ocean acidification and palaeotemperature were contributing to the species adaptations identified across the Triassic-Jurassic boundary interval.

People have varied and complex relationships with stone, in its raw geology and in its altered forms. Often, however, in cultural contexts, stone remains in the background, as a taken for granted and unremarkable element of the material world. In this thesis, stone moves into the foreground. The research presented here explores how close attention to those who work intimately with stone can disclose unexpected and absorbing stories. The cultural geologies extracted and presented in this thesis cast light on the diversity of ways in which people relate to, and with, the land; and experiment with a range of different ways in which these relations can be narrated. Set on the Jurassic Coast, in the south west of England, the stone exposures that emerge along the margin between land and sea offer a productive site for developing a cultural geological approach. The limestones, shales and clays are framed, in this work, by the narratives of quarrymen and geologists. The work explores how their particular knowledges are formed, and how they exist within wider historical and ecological understandings. Their narratives bring the stratigraphy to life, and draw attention to the hidden worlds within it. The different priorities and perspectives of quarrymen and geologists are shown to lead in different directions, interweave, or run parallel. The very specific languages and descriptions they employ reveal a level of complexity and richness of detail that is mirrored in the stone. Using an approach that combines close observation and creative practice, this study examines stone at a variety of scales, and in different contexts. The work engages with specific stone types, landscapes, voids, buildings and objects. Processes of working stone through practices of lettering, sculpture and masonry elicit understandings of the material that reach far beneath its surface. The absent spaces of quarries are then explored, showing how voids can be animated with knowledge, and how destructive processes can generate creative potential, when sensitively worked and considered. Lastly, the study draws all these ideas together in a discussion of stone assemblages in buildings, to see how voices from geology and quarrying can foster greater understanding of how buildings were constructed in the past, and how we conserve them into the future.

Les roches mères marines présentent des hétérogénéités spatiales et temporelles de répartition et de qualité. Leur dépôt et leurs variations sont des phénomènes complexes résultant de l’interaction de plusieurs processus. Ces derniers ont fait l’objet de nombreuses études, mais le débat sur leurs impacts relatifs reste vif. L’évolution des outils de modélisation numérique permet désormais une approche quantitative et ouvre la voie à l’étude des couplages entre ces processus. La bonne connaissance géologique acquise sur les bassins sédimentaires du Jurassique inférieur d’Europe et la présence de plusieurs niveaux de roche mère en font un cas idéal pour caractériser les processus gouvernant la distribution de la matière organique (MO). Cette thèse présente l’étude et la modélisation numérique de ces bassins qui ont permis de déterminer l’influence relative des facteurs de contrôle de la distribution de la MO à différentes échelles. Ces travaux apportent de nouveaux éléments au débat portant sur le rôle relatif de ces processus. L’impact primordial de la morphologie des bassins mis en avant va à l’encontre de la littérature dominante dans laquelle la production et la conservation de la MO occultent les autres facteurs. Ces deux processus jouent à l’évidence un rôle important, mais les modalités de leur expression sont entièrement dépendantes de la morphologie des bassins. L’ensemble de ces travaux met en avant la nécessité d’élargir le débat pour une meilleure compréhension de la distribution globale des roches mères, en testant la même approche modélisatrice sur d’autres intervalles riches en MO, dans d’autres contextes paléogéographiques et pour d’autres types de kérogène. / Marine source-rocks have heterogeneities both in their distribution and quality over time and space. The deposition of these organic-rich sediments and their variations are complex phenomena resulting from the convergence of several processes which were the subject of many studies. However, the debate on their relative roles and impacts remains strong. The evolution of numerical modelling tools now allows a quantitative approach and new studies about the interaction between these processes. Because of their general context and the presence of several source-rocks, the Lower Jurassic sedimentary basins of Europe are an ideal case to characterize the processes governing the distribution of organic matter (OM). This thesis present the study and the numerical modelling of these basins which allowed to determine the relative influence of the control factors of the OM distribution at various scales. These works bring new elements into the debate about the relative role of these processes. The primary impact of the basin morphology highlighted by these works goes against the dominant literature in which the production and preservation of OM conceal the other factors. Both of these processes obviously play an important role in the distribution of organic-rich layers, but their setting are entirely dependent on the basin morphology. All this work highlights the need to widen the debate for a better understanding of the source rock global distribution, by using the same modelling approach with others organic-rich intervals, others palaeogeographic contexts and for others kind of kerogens.

The Lower Cretaceous Cedar Mountain Formation preserves several vertebrate faunas and has the potential of providing critical timing information pertaining to Early Cretaceous dinosaurs and the Sierran magmatic arc. Historically, the Morrison/Cedar Mountain contact and the duration of the unconformity between them have been difficult or impossible to determine because 1) the formations were deposited in similar environments, 2) the basal Cedar Mountain Formation is composed of reworked Morrison Formation, and 3) there are no radiometric ages for the lower Cedar Mountain Formation. A stratigraphic study through central Utah reveals a diagnostic suite of pedogenic and sedimentologic characters across the previously enigmatic boundary. The uppermost Morrison Formation is characterized by redoximorphic paleosol features, including iron concentrations, manganese-coated grains, and intense red-purple-green mottling. Upsection increases in chert-pebble lags and channelized conglomerates within the paleosol section indicate a period of reduced accommodation space in the Tithonian. The paleosols are usually capped by a groundwater or pedogenic carbonate. This unit is consistently present from Green River, Utah to the Utah-Colorado border. The lower Cedar Mountain Formation above this package is a poorly sorted mixture of fine-grained material and sand-gravel sized chert grains. Within a sequence stratigraphic framework, these characters record a terrestrial sequence boundary in the uppermost Morrison Formation and degradational-aggradational systems tracts in the Cedar Mountain Formation. To resolve the lack of age control for the basal Cedar Mountain Formation, a geochronologic zircon study was conducted near the Dalton Wells dinosaur quarry, Moab, Utah. The Dalton Wells quarry, along with numerous other fossil assemblages occurs in the basal Yellowcat Member. Zircons from the Dalton Wells quarry and a correlative eggshell site place the age of this horizon near the Barremian/Aptian boundary at ~124 Ma. Thus, the Yellowcat fauna is time equivalent with the feathered dinosaurs of the Yixian Formation, of Liaoning, China. This age constrains the Morrison/Cedar Mountain unconformity to a period of magmatic quiescence in western North America from 148 Ma-124 Ma. The basal Cedar Mountain age coincides with renewed magmatic activity at ~125 Ma. The Cedar Mountain Formation covers a period of 27 Myr and likely contains numerous small unconformities.

Les objectifs de cette thèse sont (1) de définir les facteurs contrôlant le développement à grande échelle des plateformes carbonatées intracratoniques et (2) de relier la diagenèse précoce des discontinuités avec les paléoenvironnements et les modèles de stratigraphie séquentielle. L’évolution de la plateforme carbonatée de l’ouest de la France a été reconstituée de l’Aalénien à l’Oxfordien (17 millions d’années). La topographie du socle contrôle la répartition latérale des bathymétries jusqu’au Bathonien moyen. La tectonique régionale favorise ou empêche localement la production carbonatée. À l’échelle des bassins ouest-téthysiens, des phases généralisées de disparition et de croissance des plateformes carbonatées sont contrôlées par les variations du climat d’une période de 9 millions d’années. La production carbonatée est faible pendant les périodes humides et importante au cours des périodes sèches perturbées par de courtes moussons. Des analyses isotopiques (δ18O et δ13C) à haute résolution ont été réalisées sur des ciments précoces variés localisés sous des discontinuités, permettant de reconstituer l’histoire paléoenvironnementale aboutissant à leur formation. Les ciments en dents de chien ainsi que les ménisques et enveloppes micritiques analysées ont précipité directement en calcite faiblement magnésienne dans l’eau de mer. Un nouveau modèle reliant architecture, stratigraphie séquentielle, faciès et diagenèse précoce est proposé pour une bordure de plateforme oolithique. Sur la plateforme interne, les discontinuités passent latéralement de surfaces subaériennes à des hardgrounds marins, dont l’érosion aboutit au dépôt de niveaux à intraclastes sur la bordure de plateforme. La cimentation précoce est uniquement localisée sous les discontinuités et est absente dans la bordure de plateforme où la sédimentation est continue. / The objectives of this thesis are (1) to characterize the factors controlling the large-scale development of intracratonic carbonate platforms and (2) to link early diagenesis of discontinuities with palaeoenvironments and sequence stratigraphy models. The evolution of the western France carbonate platform is reconstructed from the Aalenian to the Oxfordian (17 million years). The basement topography controls bathymetries until the mid-Bathonian. Regional tectonics promotes or prevents locally carbonate production. General stages of carbonate platform growth and demise in western Tethyan basins are controlled by 9 million years’ climatic variations. Carbonate production is low during humid intervals and high during dry intervals disturbed by short periods of intensive rainfall. High resolution isotopic analyses(δ18O and δ13C) were performed on various early cements located below discontinuities to reconstruct the palaeoenvironmental conditions leading to their formation. Dogtooth cements, micritic meniscus and envelopes precipitated in low-magnesium calcite directly in seawater. A new model, linking architecture, facies, sequence stratigraphy and early diagenesis is proposed for an oolitic platform wedge. On the inner platform, discontinuities change laterally from subaerial surfaces to marine hardgrounds, whose erosion leads to the deposit of an intraclasts level on the platform wedge. Early cements are only located under discontinuities and are absent in the platform wedge because of a continuous sedimentation rate.