The Jurassic ammonites from the Northern Bohemia has been revised on the base of the material stored in the National Museum in Prague and the Faculty of Science, Charles University in Prague. 23 species and 19 genera, belonging to 7 families were described on the basis of this systematical revision. This ammonite assemblage indicates a proportional occurence of the Boreal, Tethyan and also cosmopolitan taxa. Stratigraphically important taxa suggest a considerably longer period of sedimentation, predominantly represented by the Upper Jurassic carbonates. This interval may contain up to 9 ammonite zones. A pilot microfacial analysis of carbonates from Peškova stráň area (in Krásná Lípa vicinity) indicates a considerably higher variability of sedimentation area. The presence of micritic carbonates suggests the existence of a widespread areas in the Late Jurassic sea covering the Bohemian Massif. The biostratigraphy and palaeogeography is briefly discussed in the European Late Jurassic context. Key words: ammonites, Upper Jurassic, Northern Bohemia, carbonate sediments, biostratigraphy, palaeogeography

Mineralogical and petrographic analyses of the upper Jurassic - lower Cretaceous units in the vicinity of the Dinosaur National Monument quarry near Jensen, Utah, have elucidated their characteristics and the locations of formational boundaries. The lower part of the Morrison Formation is distinguished by a decreased amount of illite and an increased amount of kaolinite. In contrast, the underlying Curtis Formation contains an approximately equal mixture of illite and kaolinite. The lower Salt Wash Member and the upper Brushy Basin Member of the Morrison are both lithologically and mineralogically identifiable in this area. Above the boundary between the two, kaolinite decreases and illite increases. The strata above the Morrison, here recognized as an extension of the Cedar Mountain Formation, reveal another change in clay content. They contain kaolinite as the dominant clay mineral, whereas illite is almost completely absent. The upper Curtis Formation is a near-shore marine deposit, whereas the members of the Morrison Formation are fluvial and lacustrine. A possible climatic or depositional change is equated with the changes in the clay content within the members of the Morrison Formation. After deposition of the Morrison, the lower Cretaceous sediments that now comprise the Cedar Mountain Formation accumulated. These formed in a transitional zone (fluvial to littoral) and were eventually covered by the Dakota Formation (littoral) and the Mowry Formation (marine).

The modern plate tectonic paradigm provides a predictive model to understand what mediates dynamic processes at both plate margins and intraplate settings. At some locations on the Earth, the geological record provides evidence of apparent violations of this theoretical framework. In this dissertation, I examine a region on the rifted continental margin of Eastern North America, where at least four distinct episodes of magmatism occurred (in the Late Triassic, Early Jurassic, Early Cretaceous) since the onset of rifting and ultimate breakup of the supercontinent Pangea. It also coincides with a present-day low seismic velocity anomaly in the upper mantle. No other region on the Eastern North American Margin has a record of such anomalous dynamic processes occurring and persisting for more than 200 Myr. In this dissertation, I primarily use zircon U-Pb geochronology to establish the basic chronological framework in which magmatic and magmatic-hydrothermal systems in this region existed and persisted, establishing the temporal parameter space in which it will be possible to test geodynamic mechanisms for their formation. In Chapter 2, I use ultra-high precision zircon U-Pb geochronology via Chemical Abrasion-Isotope Dilution-Thermal Ionization Mass Spectrometry (CA-ID-TIMS) to test whether the onset of magmatism in the largest igneous body in this region (the White Mountain Batholith) is linked to the eruption of the vast flood basalts within the Central Atlantic Magmatic Province (CAMP) and whether its apparent duration is indeed > 50 Myr, as previous workers using whole rock K-Ar and mineral Ar-Ar geochronologic methods suggest. My work uncovered a previously unknown episode of rift-related magmatism in the region that precedes the both the CAMP and the emplacement of the White Mountain Batholith by 3 – 5 Myr. In Chapter 3, I use a combination of high-precision zircon U-Pb geochronology and absolute plate motion models to test whether the Cretaceous igneous province in this region resulted from hot spot magmatism as North America moved over the purported Great Meteor Hotspot. These results cannot falsify the hotspot hypothesis and the new zircon U-Pb ages therefore provide the best available chronological constraints for one of the longest-lived hot spot tracks on the Earth. In Chapter 4, motivated by the confirmation of age discrepancies between low- and intermediate-temperature chronometers and the zircon U-Pb ages presented in Chapter 2, I use a combination of both CA-ID-TIMS and LA-ICP-MS zircon U-Pb geochronologic techniques to place constraints on the timing and duration of magmatism for the Late Triassic-Early Jurassic province. The results of this chapter demonstrate that the magmatism of the White Mountain Magma Series occurs in discrete pulses through much of the Jurassic. Together with zircon Hf isotopic analyses from select samples, I synthesize these age results and construct a hypothesis testing framework in which it will be possible for future investigators to unravel the geodynamic complexities in this region. I provide recommendations for future work and emphasize the need for unified approaches coupling geochronology, geochemistry, and geophysics, to test the range of possible mechanisms responsible for these episodes of anomalous tectono-magmatic activity.

No description available.

<p> An unlocalised collection of ammonites from West New Guinea is described and identified. These identifications afford the basis for determining the stratigraphic position of the fauna, which ext ends from the Sowerbyi Zone of the Middle Jurassic to the Upper Valanginian. The relations of the fauna to other ammonite faunas are described and indicate the ammonites in the present collection to be most closely related to the faunas of the Pacific Realm and Ethiopian province of the Tethyan Realm. A new genus, Sulaites is described and possible sexual dimorphism is detected therein. </p> / Thesis / Master of Science (MSc)

En tant que laboratoire naturel, les énormes quantités de granites mésozoïques du sud de la Chine fournissent une occasion unique de comprendre la formation et l'évolution de la croûte mésozoïque et de guider les efforts d'exploration minière dans cette région. Quelles sont les conditions de mise en place de ces granites mésozoïques en Chine du Sud ? Quelle est la relation entre les conditions de mise en place et la minéralisation associée à ces granites mésozoïques?Nous avons établi expérimentalement les relations de phase du granite Jurassique de Qitianling en Chine du Sud. Trois échantillons représentatifs de granites métalumineux contenant des amphiboles ont été choisis pour définir les conditions de cristallisation de ce pluton. Des expériences de cristallisation ont été réalisées à 100-700 MPa, mais principalement à 200 MPa ou 300 MPa, à une fO₂ de ~ NNO-1,3 (1,3 log sous le tampon Ni-NiO) ou ~ NNO + 2,4, à 660 ° C à 900 ° C, et à des teneurs variables en eau (~ 3-8% en poids). Le champ de stabilité des amphiboles et les données de barométrie montrent tous deux que la pression de mise en place du magma se situait autour de 300-350 MPa. Les rapports Fe / Mg amphiboles et biotites suggèrent en outre que la fO₂ magmatique se situait autour de NNO-1 ± 0,5 près du solidus, alors que les oxydes de Fe-Ti enregistrent une augmentation de fO₂ jusqu’à NNO + 1 en conditions sub-solidus. La cristallisation de l'amphibole est limitée aux conditions proches de la saturation en H₂O, nécessitant au moins 5,5% en poids de H₂O dissout à 200 MPa, ou 6 à 8% en poids à> 300 MPa. La présence d'amphibole dans des magmas siliceux métalumineux riches en K₂O indique donc des teneurs en eau significativement supérieures à la valeur canonique de 4% en poids. Les compositions de liquides expérimentaux obtenus à 200-300 MPa reproduisent la tendance géochimique définie par le pluton, ce qui suggère qu'une différenciation dans le réservoir de la croûte supérieure a pu se produire. L'ensemble de ces résultats indique que la fugacité relativement faible en oxygène, la température élevée du magma lors de sa mise en place et sa richesse en eau constituent un environnement favorable à la concentration d'éléments minéralisés au stade magmatique précoce. / As a natural laboratory, the huge amounts of Mesozoic granite distributing in South China provided a unique opportunity to unravel the Mesozoic crust formation and evolution in southern China as well as for guiding mining exploration efforts in this area. What are the emplacement conditions of those Mesozoic granite in South China? What are the relationship between the emplacement conditions and the mineralization among those Mesozoic granites?We have experimentally established the phase relationships for the tin-bearing Jurassic Qitianling granite in South China. Three representative amphibole-bearing, metaluminous granitic samples were chosen for constraining crystallization conditions of the Qitianling pluton. Crystallization experiments were performed at 100-700 MPa, albeit mainly at 200 MPa or 300 MPa, at an fO₂ of ~NNO-1.3 (1.3 log unit below the Ni-NiO buffer) or ~NNO+2.4, at 660°C to 900°C, and at variable melt water contents (~3-8 wt%). Amphibole stability field and barometry both show that the pressure of magma emplacement was around 300-350 MPa. Amphibole and biotite Fe/Mg ratios further suggest that magmatic fO₂ was around NNO-1±0.5 near solidus, while Fe-Ti oxides record an fO2 increase up to NNO+1 below solidus. Amphibole crystallization is restricted to near H₂O-saturation conditions, requiring at least 5.5 wt% H₂Omelt at 200 MPa, or 6-8 wt % at ≥ 300 MPa. Amphibole occurrence in K₂O-rich metaluminous silicic magmas thus indicates water contents significantly higher than the canonical value of 4 wt%. The experimental liquid line of descent obtained at 200-300 MPa mimic the geochemical trend expressed by the pluton suggesting that fractionation in the upper crustal reservoir could happen. We deduced that the relatively low oxygen fugacity, high liquidus temperature and melt water rich condition may be an enabling environment for concentrating the ore elements in the early magmatic stage

The purpose of this study is to analyze the sedimentology and stratigraphy of the Middle Jurassic Preuss Sandstone and re-evaluate past sedimentological interpretations. The Preuss is located in northern Utah, western Wyoming and eastern Idaho and is stratigraphically equivalent to the Entrada Sandstone, which is Callovian in age (Dossett et al., 2014). This study is the first attempt at 1) a sequence stratigraphic framework, 2) a petroleum system analysis and 3) an extraterrestrial analog study for the Preuss. This study frames the Preuss within three broad facies groups: marine, coastal and terrestrial. The marine group includes the open marine and restricted marine facies with associated subfacies, the coastal group includes coastal sabkha and associated subfacies, and the terrestrial group includes alluvial, inland sabkha and eolian facies with associated subfacies. Three sections in northern Utah and one section in eastern Idaho compromise the focus of this study. The three Utah sections were measured and described, and samples were collected from two Utah sections and the Idaho section. The Preuss Sandstone was deposited in an asymmetrical retroarc basin, consequently the Preuss thickens from the east towards west-central Utah and the Jurassic Elko highlands. The deposits are mostly terrestrial, which is in accord with recent sedimentological interpretations, but at odds with the old paradigm, which postulates that the Entrada and Preuss were largely tidal in origin. There are marine transgressions within the trough of the retroarc basin, and the transgressions affect terrestrial sedimentary patterns. During marine incurstions, alluvium shed off the highlands is confined west of the seaway, and does not prograde east of the trough until all the available accommodation is filled. The Preuss was deposited during a complete third-order sequence-stratigraphic cycle that lies within the Lower Zuni II second-order lowstand. The Preuss Sandstone can be used as an outcrop analog for ancient and modern environments both here on Earth and on other planetary bodies. The petroliferous Norphlet Formation along the U.S. Gulf Coast was deposited in an environment very similar to the Preuss, but the Waltherian succession of facies might be slightly different. Likewise, the facies present in the Preuss are analogous to modern arid environments, such as the Persian Gulf. Furthermore, the alluvial, sabkha, eolian and shallow marine facies of the Preuss are highly similar to facies observed in ancient Martian environments and modern environments on Saturn's moon, Titan.

For 130 years dinosaurs have been divided into two distinct clades – Ornithischia and Saurischia. This dissertation looks at the earliest evolution of the clade Dinosauria by focusing upon the interrelationships of the major subsidiary clades within it. It does this following examination, comparison and description of early dinosaur material, and by utilising modern phylogenetic analysis techniques, to rigorously and objectively test the fundamental groupings within the clade Dinosauria using a newly compiled dataset of early dinosaurs and other dinosauromorphs (= close dinosaur relatives). The current consensus on how the principal clades within Dinosauria (Theropoda, Sauropodomorpha and Ornithischia) are related to one another is challenged by the results of these analyses. This study finds, for the first time, a sister-group relationship between Ornithischia and Theropoda, here termed Ornithoscelida. Consequently, a new definition for Dinosauria is presented, as the historic definition would exclude all members of Sauropodomorpha from the clade. As well as this, I propose revisions to the definitions of each of the principal dinosaurian sub-divisions and propose a new timeframe and geographic setting for the origin of Dinosauria. These new hypotheses force re-evaluations of early dinosaur cladogenesis and character evolution, suggest the independent acquisition of hypercarnivory in multiple dinosaur groups and offers an explanation for many of the anatomical features previously regarded as striking convergences between theropods and early ornithischians. As well as presenting new anatomical data on many early dinosaurs and dinosauromorphs, including a comprehensive re-description of the postcranial anatomy of Lesothosaurus diagnosticus (Chapter 2), and a new anatomical dataset of early dinosaurs (the largest ever compiled), this thesis goes on to implement the new dataset to investigate a number of important outstanding questions about early dinosaur evolution and provides new lines of enquiry for future workers to pursue. The results of this thesis reveal the oldest known members of the dinosaurian clades Theropoda and Sauropodomorpha (Chapter 6), as well as a new clade within Ornithischia; a taxon previously thought to represent a derived theropod has been recovered as a potential ‘missing link’ between theropods and ornithischians using the new dataset. This work now provides a unique tool for the assessment of the phylogenetic affinities of early dinosaurs and dinosauromorphs and, once published, will hopefully become the benchmark dataset for palaeontologists working in this area.

L’évolution des dinosaures sauropodomorphes et la radiation des grands sauropodes sont encore loin d'être comprises, ni même datées avec précision. Si les premiers sauropodes semblent apparaître à la fin du Trias, ils ne se diversifient qu'à partir du Jurassique moyen. L’incertitude entourant la définition à donner au clade Sauropoda est une des principales causes de l'absence de consensus quant à la transition prosauropodes – sauropodes. C’est ce problème du « stem-group » des sauropodes qui est abordé dans cette thèse. Certains prosauropodes sont ainsi aujourd’hui considérés comme des sauropodes à part entière par certains auteurs. Ces taxons basaux diffèrent cependant beaucoup selon les auteurs. La multiplication des analyses cladistiques n’a rien résolu puisque celles-ci n’ont jamais été comparées entre elles.La découverte en 2008, par une équipe du MNHN, dans le Jurassique inférieur du Lesotho, d'un squelette de prosauropode articulé sert ici de base à une étude anatomique et systématique des sauropodomorphes basaux. De nombreux autres restes de dinosaures inédits du Lesotho appartenant aux collections du MNHN viennent compléter le matériel d’étude. Parmi ceux-ci, du matériel rapporté au prosauropode de Maphutseng et des fossiles attribués au genre Meroktenos sont entièrement décrits en détail pour la première fois.Une comparaison critique et détaillée des analyses phylogénétiques antérieures a été réalisée en utilisant la méthode de cladistique comparée telle qu’elle a été formalisée par Sereno en 2009. Elle a permis de démontrer l’impact très important du choix des caractères et de leur codage sur la topologie des arbres. Suite à cela, un premier retour sur une liste compilée de 449 caractères a été effectué. Il a nécessité la vérification d’une matrice de 15 000 à 20 000 cellules, et plus de 1300 mesures. Ce retour aux caractères ont entraîné la suppression de plus d’une centaine de caractères, et la création d’une matrice inédite de 49 unités taxonomiques et 308 caractères. Les résultats de l’analyse phylogénétique de cette matrice, bien que préliminaires, soulèvent plusieurs points intéressants. Plusieurs clades, généralement retrouvés dans les analyses les plus récentes publiées par d’autres auteurs, n’apparaissent pas. En revanche, des clades qui n’avaient jusque-là jamais été retrouvés font leur apparition. Les différentes analyses pointent également du doigt le problème de l’origine des Sauropodomorpha, et relancent le débat sur l’origine du clade Sauropoda. / The evolution of sauropodomorph dinosaurs and the radiation of the large sauropods are still far from being understood and well-dated. If the first sauropods seem to appear at the end of the Triassic, they don’t start to diversify before the Middle Jurassic. The uncertainty surrounding the definition of the clade Sauropoda is one of the main causes of the lack of consensus regarding the prosauropod – sauropod transition. It is this issue of the “stem-group” of sauropods that is dealt with in this thesis. Some prosauropods are now considered to be sauropods by some authors. These basal taxa differ a lot depending on the authors. The multiplication of the cladistic analyses didn’t solve the problem as they never were compared.The discovery in 2008, by a MNHN team, in the Early Jurassic of Lesotho, of a prosauropod articulated skeleton is used herein as the basis for anatomical and systematic study of basal sauropodomorphs. Many other new dinosaur remains from Lesotho, housed in the MNHN collections, complement the study material. Among these, material referred to the Maphutseng prosauropod and fossils referred to the genus Meroktenos are described in details for the first time.A critical and detailed comparison of previous phylogenetic analyses is performed, using the comparative cladistics method as formalized by Sereno in 2009. This work allowed to highlight the significant impact of the choice of characters and their scoring on the topology of the trees. After that, a first reappraisal of a list of 449 compiled characters was carried out. It required the reexamination of a matrix consisting in 15 000 to 20 000 cells, and more than 1300 measures. This work led to remove more than one hundred morphological characters, and the building of a new matrix including 49 taxonomic units and 308 characters. The results of the phylogenetic analysis, although preliminary, raise some interesting points. Several clades, often recovered in the most recent analyses published by other authors, are not recognized here. However, clades that had, until then, never been found, are recovered. The different analyses also point out the hurdle of the origin of Sauropodomorpha, and reopen the debate on the origin of Sauropoda.

Le Haut-Atlas central est un bassin salifère structuré autour d’étroites rides diapiriques (i.e. salt walls) orientées ENE-OSO qui bordent de larges mini-bassins. L’impact de la compression cénozoïque étant relativement limitée, les structures diapiriques y sont particulièrement bien préservées. L’objectif de la thèse est d’analyser les relations entre la sédimentation et la croissance des rides diapiriques dans le cadre imposé par l’évolution du système sédimentaire, durant le Jurassique inférieur et moyen, dans la région d’Imilchil, au cœur du haut-Atlas central. Le Lias-Dogger enregistre le comblement du bassin atlasique à travers six séquences de transgression-régression de troisième ordre. Cette grande tendance régressive se manifeste par la succession de trois systèmes de dépôts. Un système carbonaté, du Toarcien au Bajocien supérieur, dont l’éventail de faciès oscille entre la rampe moyenne et la rampe externe distale. Au Bajocien supérieur l’apport de sédiments terrigènes dans le bassin provoque la disparition du système carbonaté qui est recouvert par une épaisse série sédimentaire mixte peu profonde. Ce système mixte perdure jusqu’au Bathonien inférieur puis il est progressivement remplacé par un système fluviatile silico-clastique. Les relations entre les mouvements diapiriques et la sédimentation peuvent être mises en évidence par une modification de la géométrie des dépôts, par des variations de faciès aux abords des diapirs, et/ou par des événements sédimentaires particuliers (surfaces d’érosion, brèches, niveau condensé). L’analyse de ces interactions en fonction des séquences de transgression-régression permet de définir une chronologie de l’activité diapirique. Elle est continue pendant le Jurassique inférieur et moyen mais connait une évolution polyphasée comprenant deux périodes d’activité majeure, du Toarcien à l’Aalénien terminal et du Bajocien supérieur jusqu’à ce que les diapirs soient scellés au Bathonien supérieur-Callovien inférieur. Ces deux périodes encadrent un épisode de plus faible intensité pendant la progradation et le développement de la rampe carbonatée bajocienne. Les interactions entre diapirisme et sédimentation sont synthétisées dans un modèle empirique à travers quatre types de prismes de dépôts, définis selon des critères géométriques et sédimentologiques, et qui rendent compte de la configuration du système sédimentaire, ainsi que de la position du diapir et de sa couverture au moment du dépôt : A plus grande échelle l’influence du développement des mini-bassins sur la sédimentation s’exprime par une distribution préférentielle des faciès sédimentaire dans les systèmes de dépôt carbonaté et mixte. Les faciès proximaux, et en particulier les faciès granulaires de haute énergie, se regroupent autour des rides diapiriques tandis que les faciès distaux de basse énergie se concentrent dans l’axe des mini-bassins. / The High-Atlas salt basin is formed by a set of ENE-WSW-trending and 15-to-80-kilometers-long narrow diapiric ridges (i.e. salt walls) bounding large mini-basins mildly deformed during Cenozoic shortening. The aim of this thesis is to analyze the relationships between sedimentation and diapiric growth during the Lower and Middle Jurassic in the Imilchil region (Central High-Atlas). In this area, the Lias and Dogger series form a large regressive trend composed by six third-order transgression-regression (T/R) sequences and characterized by the succession of three sedimentary systems. A carbonate system develop from Toarcian to Upper Bajocian, with a facies range from middle ramp to distal outer ramp. From Upper Bajocian, a terrigenous supply in the basin causes the end of the carbonate system and leads to the deposition of a thick shallow mixed unit. From Lower Bathonian, this mixed sedimentary system is gradually replaced by an alluvial silici-clastic system. Relationships between diapiric movements and sedimentation are interpreted from depositional geometries, facies variations in the vicinity of diapirs and/or particular sedimentary events (erosional surfaces, breccia, condensed levels). The analysis of these interactions, based on T/R sequences, enables to define a chronology of the diapiric activity in the Imilchil area. The activity is continuous during the Lower and Middle Jurassic but shows a non-linear development with two phases of high-intensity, one from Toarcian to Uppermost Aalenian, and one from Upper Bajocian. These two phases surround a period of low-intensity during the progradation and the development of the bajocian carbonate ramp system. Interactions between diapirism and sedimentation are summarized in an empirical model consisting of four types of depositional prisms defined by geometrical and sedimentological criteria. On a larger scale, the impact of the mini-basin on the sedimentation is characterized by a specific facies distribution in the carbonate and mixed depositional system. The high-energy granular facies are concentrated around the diapiric structures and the distal low-energy facies are deposited in the axis of the mini-basins.