No description available.

Bien qu'ayant fait l'objet d'études depuis près de deux siècles, les sélaciens (requins et raies) du Crétacé supérieur du Bassin Anglo-Parisien ne sont que partiellement connus. L'étude de 22 faunes provenant de gisements d'âges Cénomanien à Campanien en Grande Bretagne et nord de la France a permis d'améliorer significativement les connaissances sur ces communautés de sélaciens. Les horizons échantillonnés, principalement représentés par des craies phosphatées, ont livré environ 38000 restes dentaires. Ces derniers ont permis l'identification et la description de 150 taxa comprenant 130 espèces de requins et 20 espèces de batoïdes. En plus d'un nombre important de nouvelles occurrences stratigraphiques et géographiques, cette étude décrit 25 nouvelles espèces et 7 nouveaux genres en dehors de taxa, probablement nouveaux, laissés en nomenclature ouverte. Le nombre important de taxa considérés, combiné à des données publiées sur les sélaciens du nord-ouest de l'Europe et du Western Interior Seaway, ont permis d'étudier différents événements dans la diversité de ce groupe, à travers l'utilisation de méthodes de raréfaction et de ré-échantillonnage. Plusieurs bioévénements ont pu être identifiés et corrélés à différents changements environnementaux. De nombreux aspects paléoécologiques de ces faunes sont aussi discutés. Diverses méthodes d'ordination (clusters, analyses de correspondance) ont été appliquées à la fois sur les données morpho-fonctionelles (types dentaires préalablement testés sur des faunes actuelles) et taxonomiques des 22 faunes considérées. Plusieurs facteurs environnementaux sont proposés pour expliquer la distribution observée et les affinités paléoenvironnementales de certains taxa sont discutées. Différentes mesures de diversité ont permis d'identifier l'hétérogénéité de l'habitat comme principal facteur contrôlant la diversité et dominance d'espèces dans les faunes santoniennes et campaniennes. La diversité beta des nombreuses faunes du Campanien inférieur a été étudiée et indique une absence de provincialité dans le bassin. Enfin, les comparaisons faites avec des faunes publiées du nord-ouest de l'Euro pe ont permis d'identifier les distributions paléoécologiques générales pour ce groupe. / Although studied for nearly two centuries, Late Cretaceous selachians (sharks, rays and skates) from the Anglo-Paris Basin are still imperfectly known. The study of 22 selachians (sharks, rays and skates) faunas from Cenomanian to Campanian horizons in Great Britain and northern France allowed a significant advance in our knowledge on these assemblages and their communities. The (mainly phosphatic) chalks sampled yielded about 38 000 selachian fossil remains, mostly teeth. 150 taxa, comprising 130 shark and 20 batoid species, were identified and described. In addition to the large number of new stratigraphic and geographic ranges recognised here, 25 new species and 7 new genera are described beside a number of new taxa that are left in open nomenclature. The large number of taxa included in this work, along with other published data from NW Europe and Western Interior Seaway, allowed diversity patterns of Late Cretaceous selachians to be studie d through the use of various rarefaction and re-sampling methods. The various bioevents identified could all be correlated to global environmental changes such as temperature and sea level variations as well as changes in water mass distribution. Several palaeoecological aspects of these assemblages are also discussed. The use of morpho-functional dental types provided a promising approach area in assessing changes in the morpho-functional structure of some modern selachian assemblages depending on environmental conditions. Ordination methods (clusters, CA) used on both the taxonomic and morpho-functional structure of the faunas considered here, allowed the identification of groupings among the different assemblages. Accordingly, various environmental factors are proposed to explain the observed distribution and the palaeoenvironmental affinities of some taxa are discussed. Diversity measurements proved to be rich in information and allowed the identification of habitat hete rogeneity as the main controlling factor on the diversity and evenness of the Santonian-Campanian faunas. The beta diversity of the numerous Early Campanian faunas is also discussed and indicates low provinciality in the basin. Finally, comparisons with other assemblages from other NW basins allowed general palaeoecological distributions to be identified.

Mosasauria is a clade of essentially Late Cretaceous marine reptiles. Although well known by several nicely preserved specimens, phylogenetic relationships of mosasaurians within Squamata are still a matter of intense debate. Most of the works discussing the relationships of mosasaurians in global contexts of squamates were based mainly on more derived taxa, including only few basal forms. Here the anatomy, phylogeny, ontogeny and taxonomy of the basalmost mosasaurian radiation, the commonly known \"dolichosaurs\", is reviewed, mostly on the light of new and exquisitely preserved coniasaur remains from Texas. New remains described here encompass dozens of specimens, including a new species represented by a gravid female and several embryos. A revision of the genus Coniasaurus suggest it as encompassing four species: C. crassidens, C. longicollis (former Dolichosaurus longicollis), C. gracilodens and the new taxon described here. Contrary to what is observed in more derived forms, the patterns of tooth attachment in coniasaurs are very similar to those of varanoids, suggesting similarities between tooth attachment and implantation in snakes and derived mosasaurs to be the result of homoplasies. The evolution of the dolichosaurian postcranial anatomy is assessed, finding new diagnostic characters for several distinct lineages. A phylogenetic analysis of Mosasauria in a global matrix of squamates, including the largest sample of basal forms ever tested, consistently found the group to be closely related to Varanoidea, rejecting the hypotheses of the group being closely related either to snakes or lying in a more basal position among squamates. Results gathered by this thesis are expected to greatly contribute to the knowledge of this astonishing group / Mosasauria é um clado formado essencialmente por répteis marinhos do Cretáceo Superior. Embora bem conhecido por diversos espécimes, as relações filogenéticas do grupo dentro de Squamata formam um tópico de intenso debate. A maior parte dos trabalhos discutindo o tema em análises globais de Squamata foram baseadas em táxons mais derivados, incluindo apenas poucas formas basais. Aqui, a anatomia, filogenia, ontogenia e taxonomia da irradiação mais basal do grupo, os \"dolicossauros\", foi revista, principalmente à luz de novos restos fósseis de coniassauros do Texas. Os novos fósseis descritos aqui englobam dezenas de espécimes, incluindo uma nova espécie representada por uma fêmea gravida e diversos embriões. Uma revisão do gênero Coniasaurus sugere que o mesmo engloba quatro espécies: C. crassidens, C. longicollis (antes Dolichosaurus longicollis), C. gracilodens e o novo táxon descrito aqui. Ao contrário do observado em formas mais derivadas, os padrões de fixação dentária nos coniassauros é muito similar àqueles dos varanóides, sugerindo que as similaridades observadas nestes padrões entre serpentes e mosassauros derivados resulta da ocorrência de homoplasias. A evolução do esqueleto pós-craniano dos dolicossauros foi avaliada, encontrando novos caracteres diagnósticos para diferentes linhagens. Uma análise filogenética de Mosasauria em uma matriz global de Squamata, incluindo a maior amostragem de formas basais já testada, consistentemente encontrou o grupo como proximamente relacionado ao clado Varanoidea, rejeitando hipóteses de proximidade com serpentes ou numa posição mais basal dentro de Squamata. Espera-se que os resultados provenientes desta tese contribuam consideravelmente para o conhecimento deste incrível grupo

This study involved a regional hydrogeological assessment of the Comox Coalfield on Vancouver Island, British Columbia. Two site-specific geological and hydrogeological investigations were conducted. The first involved generating a 2.5 dimensional hydrostratigraphic model of part of the Quadra Sand Comox-Merville Aquifer using lithology information from 196 drilled domestic-use groundwater wells. Well logs were standardized with respect to lithologic and hydraulic characteristics. Contact surfaces were created for identifiable hydrostratigraphic units employing an iterative geostatistical interpolation process that incorporated contact points from well logs and interpreted points based on the regional hydrogeology. Modeled hydrostratigraphic surfaces were compared to logged contacts and to exposures at Willemar and Lazo bluffs at Comox. Six lithostratigraphic units were identified in the coastal exposures. Hydraulic conductivity values, estimated from grain size data using the Hazen method, for the lowermost 4 units were: 2.3 x 10-3 cm/s, 9.1 x 10-6 cm/s, 9.4 x 10-3 cm/s, and 4.7 x 10-6 cm/s, respectively. The hydrostratigraphic model was verified using statistical variance analysis, field reconnaissance data, and the identification of a separate surficial aquifer within the study area. The model identified all units mapped in the field and two units below sea level, inferred to be the Cowichan Head Formation. The Comox Bluff model successfully predicted, within 2 m vertically, subsurface hydrostratigraphic boundaries 80% of the time. The second component of the study included a hydrogeological investigation of stacked Quaternary and Late Cretaceous bedrock aquifers at Oyster River. This investigation incorporated drilling logs, borehole geophysics, aqueous geochemistry, pumping and recovery test data, and hydrostratigraphic interpretation of surficial exposures. The potential for hydraulic communication between the Late Cretaceous Nanaimo Group fractured sedimentary bedrock and the overlying unconsolidated Quaternary aquifers was examined. Two adjacent groundwater observation wells were drilled; one completed in bedrock (146.9 m) and one in the surficial sediments (7.3 m). The deeper well penetrated the Trent River and Comox Formations of the Nanaimo Group. A water-bearing fracture zone approximately 3 m wide was encountered at 135 metres below ground surface, coincident with the Comox Y and Y Lower coal seams. Dissolved methane gas was detected in the bedrock aquifer, with an initial concentration of 2,123 mg/L. Schoeller diagrams reveal that the gas in bedrock is coal related. A pumping and recovery test in the deep well suggests that there is unlikely any hydraulic communication between the bedrock and surficial aquifers encountered at Oyster River. This assessment is based on infrequent water level measurements in the shallow well, which did not consistently draw down during pumping of the deeper well. However, the pumping rate was not sustainable for this test and it could not be held constant. Fracture transmissivity and hydraulic conductivity for the bedrock aquifer were estimated using the Theis Recovery method at 7.06 x 10-7 m2/s and 2.29 x 10-7 m/s, respectively. The hydrogeological research conducted at Comox and Oyster River highlights the effectiveness of a multidisciplinary approach for subsurface investigations. This study contributes site level data upon which regional inferences can be built for the Comox Coalfield.

Estudo realizado nas rochas vulcânicas associadas ao estágio pré-evaporítico da Bacia de Campos, a partir de testemunhos de 4 furos de sondagens. Estes litotipos são importantes no contexto da evolução tectônica e estratigráfica da bacia e o objetivo deste trabalho é a caracterização destas rochas a partir da petrografia, litoquímica, química mineral e composição isotópica Sr-Nd. A aplicação das metodologias de estudos convencionais foi dificultada devido ao grau de alteração das rochas marcado por modificações mineralógicas (substituição de minerais por argilominerais, palagonitização do vidro vulcânico, sericitização dos plagioclásios e presença de vesículas), elevado LOI e identificação de sedimentos arenosos englobados pela rocha vulcânica. Para minimizar os efeitos da alteração, empregaram-se metodologias que permitiram avaliar o grau de alteração das amostras e a mobilidade dos elementos químicos na rocha total. Os resultados obtidos estabelecem que as rochas vulcânicas são basaltos originados a partir de magmas com composição subalcalina, toleítica a transicional, baixo TiO2 e alto magnésio. Os ETRs estão em conformidade com o padrão dos basaltos toleíticos baixo TiO2 da Formação Serra Geral e são comparáveis aos E-MORB do Oceano Atlântico. O piroxênio dominante é a augita e quimicamente confirmam que os basaltos pertencem a série subalcalina e transicionais entre a série cálcio-alcalina e toleítica. Isotopicamente estão associados ao componente mantélico EMII e seguem o comportamento dos basaltos da Bacia de Campos com alto potássio. Os parâmetros levantados estabelecem uma correlação das rochas vulcânicas do Andar Alagoas da Bacia de Campos com os basaltos intracontinentais da Bacia do Paraná. / Study of the volcanic rocks associated with the pre-evaporitic stage of the Campos Basin, done from the boring cores of four boreholes. These lithotypes are important in the tectonic and stratigraphic evolution context of the basin and this study aims to characterize these rocks based on petrography, lithochemistry, mineral chemistry and Sr-Nd isotopic composition. The dating performed by the 40Ar/39Ar method in the feldspar minerals proved inadequate. The application of conventional study methodologies was difficult due to the degree of alteration of the rocks, evidenced by mineralogical changes (replacement of minerals by clay minerals, palagonitization of volcanic glass, sericitization of plagioclase and presence of vesicles), high LOI and identification of sandy sediments enclosed by the volcanic rock. In order to minimize the alteration effects, methodologies were used that allowed evaluating the degree of alteration of the samples and chemical element mobility in the whole rock. The results establish that the volcanic rocks are basalts derived from magmas with subalkaline composition, tholeiitic to transitional, low TiO2 and high magnesium. The REE are in conformity with the standard tholeiitic basalts of low TiO2 of the Serra Geral Formation and are comparable with the E-MORB from the Atlantic Ocean. The dominant pyroxene is augite which chemically confirms that the basalts belong to the subalkaline series and the transitional series between the calc-alkaline and tholeiitic series. They are isotopically associated with the mantle component EMII and follow the behavior of the Campos Basin basalts with high potassium. The collected parameters establish a correlation of the volcanic rocks of the Alagoas Stage in the Campos Basin with the intracontinental basalts of the Paraná Basin.

Estudo realizado nas rochas vulcânicas associadas ao estágio pré-evaporítico da Bacia de Campos, a partir de testemunhos de 4 furos de sondagens. Estes litotipos são importantes no contexto da evolução tectônica e estratigráfica da bacia e o objetivo deste trabalho é a caracterização destas rochas a partir da petrografia, litoquímica, química mineral e composição isotópica Sr-Nd. A aplicação das metodologias de estudos convencionais foi dificultada devido ao grau de alteração das rochas marcado por modificações mineralógicas (substituição de minerais por argilominerais, palagonitização do vidro vulcânico, sericitização dos plagioclásios e presença de vesículas), elevado LOI e identificação de sedimentos arenosos englobados pela rocha vulcânica. Para minimizar os efeitos da alteração, empregaram-se metodologias que permitiram avaliar o grau de alteração das amostras e a mobilidade dos elementos químicos na rocha total. Os resultados obtidos estabelecem que as rochas vulcânicas são basaltos originados a partir de magmas com composição subalcalina, toleítica a transicional, baixo TiO2 e alto magnésio. Os ETRs estão em conformidade com o padrão dos basaltos toleíticos baixo TiO2 da Formação Serra Geral e são comparáveis aos E-MORB do Oceano Atlântico. O piroxênio dominante é a augita e quimicamente confirmam que os basaltos pertencem a série subalcalina e transicionais entre a série cálcio-alcalina e toleítica. Isotopicamente estão associados ao componente mantélico EMII e seguem o comportamento dos basaltos da Bacia de Campos com alto potássio. Os parâmetros levantados estabelecem uma correlação das rochas vulcânicas do Andar Alagoas da Bacia de Campos com os basaltos intracontinentais da Bacia do Paraná. / Study of the volcanic rocks associated with the pre-evaporitic stage of the Campos Basin, done from the boring cores of four boreholes. These lithotypes are important in the tectonic and stratigraphic evolution context of the basin and this study aims to characterize these rocks based on petrography, lithochemistry, mineral chemistry and Sr-Nd isotopic composition. The dating performed by the 40Ar/39Ar method in the feldspar minerals proved inadequate. The application of conventional study methodologies was difficult due to the degree of alteration of the rocks, evidenced by mineralogical changes (replacement of minerals by clay minerals, palagonitization of volcanic glass, sericitization of plagioclase and presence of vesicles), high LOI and identification of sandy sediments enclosed by the volcanic rock. In order to minimize the alteration effects, methodologies were used that allowed evaluating the degree of alteration of the samples and chemical element mobility in the whole rock. The results establish that the volcanic rocks are basalts derived from magmas with subalkaline composition, tholeiitic to transitional, low TiO2 and high magnesium. The REE are in conformity with the standard tholeiitic basalts of low TiO2 of the Serra Geral Formation and are comparable with the E-MORB from the Atlantic Ocean. The dominant pyroxene is augite which chemically confirms that the basalts belong to the subalkaline series and the transitional series between the calc-alkaline and tholeiitic series. They are isotopically associated with the mantle component EMII and follow the behavior of the Campos Basin basalts with high potassium. The collected parameters establish a correlation of the volcanic rocks of the Alagoas Stage in the Campos Basin with the intracontinental basalts of the Paraná Basin.

Estudo realizado nas rochas vulcânicas associadas ao estágio pré-evaporítico da Bacia de Campos, a partir de testemunhos de 4 furos de sondagens. Estes litotipos são importantes no contexto da evolução tectônica e estratigráfica da bacia e o objetivo deste trabalho é a caracterização destas rochas a partir da petrografia, litoquímica, química mineral e composição isotópica Sr-Nd. A aplicação das metodologias de estudos convencionais foi dificultada devido ao grau de alteração das rochas marcado por modificações mineralógicas (substituição de minerais por argilominerais, palagonitização do vidro vulcânico, sericitização dos plagioclásios e presença de vesículas), elevado LOI e identificação de sedimentos arenosos englobados pela rocha vulcânica. Para minimizar os efeitos da alteração, empregaram-se metodologias que permitiram avaliar o grau de alteração das amostras e a mobilidade dos elementos químicos na rocha total. Os resultados obtidos estabelecem que as rochas vulcânicas são basaltos originados a partir de magmas com composição subalcalina, toleítica a transicional, baixo TiO2 e alto magnésio. Os ETRs estão em conformidade com o padrão dos basaltos toleíticos baixo TiO2 da Formação Serra Geral e são comparáveis aos E-MORB do Oceano Atlântico. O piroxênio dominante é a augita e quimicamente confirmam que os basaltos pertencem a série subalcalina e transicionais entre a série cálcio-alcalina e toleítica. Isotopicamente estão associados ao componente mantélico EMII e seguem o comportamento dos basaltos da Bacia de Campos com alto potássio. Os parâmetros levantados estabelecem uma correlação das rochas vulcânicas do Andar Alagoas da Bacia de Campos com os basaltos intracontinentais da Bacia do Paraná. / Study of the volcanic rocks associated with the pre-evaporitic stage of the Campos Basin, done from the boring cores of four boreholes. These lithotypes are important in the tectonic and stratigraphic evolution context of the basin and this study aims to characterize these rocks based on petrography, lithochemistry, mineral chemistry and Sr-Nd isotopic composition. The dating performed by the 40Ar/39Ar method in the feldspar minerals proved inadequate. The application of conventional study methodologies was difficult due to the degree of alteration of the rocks, evidenced by mineralogical changes (replacement of minerals by clay minerals, palagonitization of volcanic glass, sericitization of plagioclase and presence of vesicles), high LOI and identification of sandy sediments enclosed by the volcanic rock. In order to minimize the alteration effects, methodologies were used that allowed evaluating the degree of alteration of the samples and chemical element mobility in the whole rock. The results establish that the volcanic rocks are basalts derived from magmas with subalkaline composition, tholeiitic to transitional, low TiO2 and high magnesium. The REE are in conformity with the standard tholeiitic basalts of low TiO2 of the Serra Geral Formation and are comparable with the E-MORB from the Atlantic Ocean. The dominant pyroxene is augite which chemically confirms that the basalts belong to the subalkaline series and the transitional series between the calc-alkaline and tholeiitic series. They are isotopically associated with the mantle component EMII and follow the behavior of the Campos Basin basalts with high potassium. The collected parameters establish a correlation of the volcanic rocks of the Alagoas Stage in the Campos Basin with the intracontinental basalts of the Paraná Basin.

Diagenetic and structural aspects of tight gas sandstones must be addressed concurrently in order to fully understand low-permeability sandstones and to better predict their reservoir quality attributes that arise from a combination of pore-scale and fracture distribution characteristics. This dissertation focuses on aspects of rock evolution that are germane to concurrent structural and diagenetic evolution, such as loading and thermal history, rock mechanical property evolution, and fracture timing. I tested the hypothesis that the cement precipitation step, governed by thermal exposure and grain surface attributes, governs how sandstone attributes evolve using observations from the Late Cretaceous Williams Fork sandstones from the Piceance Basin, Colorado. My research shows that essential information for predicting and understanding fracture patterns in sandstone can be obtained by unraveling cement precipitation (diagenetic) history. Fractures depend on the mechanical properties existing during fracture growth. I show that key rock mechanical properties (subcritical crack index, Young's modulus and Poisson's ratio), petrophysical behavior, and reservoir quality depend in a systematic way on time-temperature history and the intrinsic grain surface attributes of these sandstones. I classified the Williams Fork lithofacies petrographically and correlated those with log responses to create a model that can be used to predict reservoir quality and diagenesis directly from well logs. I determined rock mechanical characteristics by measuring the subcritical crack index (SCI), a mechanical property that influences fracture distribution characteristics, and by examining log-derived bulk mechanical properties. To quantify the influence of quartz cementation on the SCI and to determine the range of SCI values for sandstone of given framework composition at different diagenetic stages, I measured SCI on Williams Fork core samples and their outcrop equivalents. Diagenetic modeling is applied to determine the sandstone characteristics during fracturing. / text

Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-09-21T15:45:10Z No. of bitstreams: 1 Rodrigo do Monte Guerra_.pdf: 12842392 bytes, checksum: b6db9de51a65dd59c144edac22f16cab (MD5) / Made available in DSpace on 2016-09-21T15:45:10Z (GMT). No. of bitstreams: 1 Rodrigo do Monte Guerra_.pdf: 12842392 bytes, checksum: b6db9de51a65dd59c144edac22f16cab (MD5) Previous issue date: 2016-01-19 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Milton Valente / O final do período Cretáceo é caracterizado por uma gradual transição climática de escala global, fator que modificou a composição das assembleias de nanofósseis calcários e por conta disso vem causando problemas nas interpretações bioestratigráficas entre diferentes faixas latitudinais. Apesar de possuir alguns estudos realizados principalmente entre as décadas de 1980 e 1990, existe uma carência na avaliação do Atlântico Sul como um todo. Desta forma, este estudo objetiva descrever as assembleias de nanofósseis calcários comuns em cada faixa latitudinal e testar o sincronismo dos principais bioeventos. Foram analisadas 649 amostras provenientes de doze seções testemunhadas pelos projetos Deep Sea Drilling Project (DSDP) e Ocean Drilling Program (ODP) nas proximidades da margem brasileira e africana, além de um afloramento na Península Antártica. O estudo taxonômico possibilitou a identificação de 197 espécies de nanofósseis calcários do Campaniano e Maastrichtiano. Através do uso conjunto da bioestratigrafia e magnetoestratigrafia, foram reconhecidos diacronismos em eventos de primeira e última ocorrência de espécies do Campaniano superior e Maastrichtiano superior. Este diacronismo está relacionado a migrações de espécies entre baixas e médias latitudes, decorrentes de mudanças na circulação oceânica e temperatura das águas superficiais. Com base na variação latitudinal das assembleias de nanofósseis calcários, um detalhado estudo bioestratigráfico possibilitou a divisão de três zoneamentos para o Atlântico Sul (baixas, médias e altas latitudes). Além disso, foram definidos os padrões de distribuição de diversas espécies, mostrando uma clara divisão paleobiogeográfica entre espécies que ocorrem somente em latitudes altas e outras limitadas a latitudes médias a baixas. Este padrão possivelmente foi controlado por variações na temperatura das massas de água superficiais. Outras espécies possuem sua distribuição variada em todas as faixas latitudinais, tendo sua distribuição relacionada provavelmente à disponibilidade de nutrientes. / The Late Cretaceous period is characterized by global climatic transition that influenced calcareous nannofossil assemblages posing a challenge for biostratigraphic interpretation between different latitudinal degrees. There are a few studies on South Atlantic calcareous nannofossils from 1980 and 1990 decades, but none of them evaluate the South Atlantic as a whole. Therefore, this study aims to describe the calcareous nannofossils assemblages in each latitudinal zone and test the bioevents synchroneity. It were selected 649 samples from twelve cored sections coming from DSDP (Deep Sea Drilling Project) e ODP (Ocean Drilling Program) close to the Brazilian and African margins, in addition to an outcrop in the Antarctic Peninsula. The taxonomic study allowed the identification of 197 calcareous nannofossils species from the Campanian and Maastrichtian. Using the correlation between the biostratigraphical data and magnetostratigraphy, it was possible to identify diachronism in some bioevents of first and last occurrences during the late Campanian and late Maastrichtian. This diachronism is related to species migration between low and mid-latitudes, due to changes in the ocean circulation and surface water temperature. Based on the latitudinal variation in the calcareous nannofossils assemblages, a detailed biostratigraphic study enabled the South Atlantic division in three zonations (low, medium and high-latitudes). We also defined the distribution pattern of some species, indicating a clear paleobiogeographical division between high latitude species and some species limited to low and mid-latitudes. This pattern was possibly controlled by surface water temperature variation. Other species have a wide distribution across the latitudes probably related to nutrient availability.

Aquesta tesi té com a objectiu fonamental la caracterització taxonòmica, biostratigràfica i paleoecològica de les associacions de caròfits de les fàcies lacustres i transicionals del Garumnià basal (Cretaci superior) de les Conques de Vallcebre, Coll de Nargó, Tremp i Àger. L’altre objectiu d’aquesta tesi és la caracterització tafonòmica i paleoecològica de les restes fòssils de plantes vasculars productores dels lignits garumnians. La flora de caròfits del Garumnià basal està constituïda per girogonits de Feistiella malladae, Peckichara cancellata, P. sertulata, Microchara cristata, M. parazensis, Platychara caudata, P. turbinata i Dughiella obtusa, i utricles de Clavator brachycerus. Pel que fa als òrgans vegetatius les calcàries garumnianes son molt riques en tal•lus de grans dimensions de Charaxis sp. associats a Peckichara sp., i de tal•lus més gràcils de Clavatoraxis microcharophorus Villalba-Breva et Martín-Closas 2011, portadors de Microchara sp. També és freqüent la presència de Munieria grambastii associada a vegades a Clavator brachycerus. Des del punt de vista biostratigràfic, les associacions de caròfits de les conques d’Àger i Vallcebre pertanyen a la biozona de caròfits Peckichara cancellata (Campanià superior - Maastrichtià inferior basal), mentre que les associacions de caròfits de les conques de Coll de Nargó i Tremp pertanyen a la biozona Septorella ultima (Maastrichtià inferior). En base a l’estudi estratigràfic i sedimentològic i l’anàlisi de microfàcies s’ha determinat que la sedimentació a la Conca d’Àger està formada majoritàriament per calcàries lacustres organitzades en centenars de seqüències de somització, que van des de fàcies lacustres profundes, passant per ambients marginals, ben il•luminats dominats per herbeis de caràcies, fins a fàcies de vora de llac dominades per herbeis de clavatoràcies. A les conques de Vallcebre, Coll de Nargó i Tremp, la sedimentació del Garumnià basal està organitzada en diversos cicles, els quals comencen amb dipòsits salabrosos formats per margues amb mol•luscs eurihalins a la base, seguits per lignits i calcàries d’ambients salabrosos dominades per porocaràcies, i calcàries d’aigua dolça amb caràcies i clavatoràcies. Les diferències en el registre sedimentari i la flora de caròfits mostren que les conques sud pirinenques presentaven una polaritat de fàcies sud-nord durant l’inici de la sedimentació continental del Cretaci superior, i que aquesta continentalització va començar al sud i desprès va continuar al nord, d’est a oest. L’estudi de la macroflora del Garumnià basal de les conques de Vallcebre, Coll de Nargó i Tremp indica que la comunitat vegetal dels aiguamolls del Maastrichtià inferior estava dominada per la conífera queirolepidiàcia Frenelopsis, que va ser la planta productora de la matèria orgànica precursora del lignit. Associada a aquestes coníferes hi havia la palmera Sabalites longirhachis, i en alguns casos altres angiospermes d’aiguamoll, representades per les seves llavors, especialment Bergacarpon viladricii Marmi, Gomez, Villalba-Breva et Martín-Closas 2012. Altres plantes vasculars significatives encara que menys abundants eren les falgueres, cicadals i pandanals. / This thesis aims to characterize the taxonomy, biostratigraphy and palaeoecology of charophyte assemblages of lacustrine and transitional facies from the basal Garumnian (Late Cretaceous) of the Vallcebre, Coll de Nargó, Tremp and Àger basins. The other objective of this study is the taphonomic and palaeoecological characterization of the precursory vascular plants of the Garumnian lignite. The charophyte flora of the basal Garumnian consists of gyrogonites of Feistiella malladae, Peckichara cancellata, P. sertulata, Microchara cristata, M. parazensis, Platychara caudata, P. turbinata and Dughiella obtusa, and utricles of Clavator brachycerus. Regarding the vegetative organs, Garumnian limestones are rich in large thalli of Charaxis sp. associated to Peckichara sp., and smaller thalli of Clavatoraxis microcharophorus Villalba-Breva et Martín-Closas 2011, with attached Microchara sp. Also Munieria grambastii thalli are abundant, associated sometimes with Clavator brachycerus. From a biostratigraphic point of view, charophyte assemblages of Vallcebre and Àger basins belong to the Peckichara cancellata biozone (Late Campanian – Earliest Maastrichtian), while charophyte assemblages of Coll de Nargó and Tremp basins belong to the Septorella ultima biozone (Early Maastrichtian). Based on the sedimentological and stratigraphic studies and microfacies analyses, the sedimentation in the Àger Basin is organised into hundreds of small order sedimentary cycles corresponding to lacustrine infilling sequences, ranging from deep lacustrine facies, through marginal environments dominated by characean meadows, to lakeshore facies dominated by clavatorecean meadows. In the Vallcebre, Coll de Nargó and Tremp basins, the deposits of the basal Garumnian are organized into small number of cycles that show a transition from brackish deposits formed by marls with euryhaline molluscs, lignites and limestones with porocharaceans, to lacustrine limestones with characeans and clavatoraceans. The differences in the sedimentary record and in the charophyte flora show that the Southern Pyrenean Basin displayed a south to north shift of facies during the onset of the Upper Cretaceous continental sedimentation and that this continentalisation began in the south and then continued to north, from east to west. The study of megafossil plant remains from the basal Garumnian of the Vallcebre, Coll de Nargó and Tremp basins indicates that the cheirolepidiacean conifer Frenelopsis was the main component of the wetlands vegetation associated with Sabalites longirhachis palms, and in some cases with other angiosperms, such as the plant bearing Bergacarpon viladricii Marmi, Gomez, Villalba-Breva et Martín-Closas 2012, probably a commelinid.