This PhD-Thesis presents a new chronostratigraphy of the Paleogene sedimentary record of the SE margin of the Eastern Ebro Basin. It is based on a number of magnetostratigraphic sections and its integration with marine and continental biochronological data. A robust correlation with the geomagnetic polarity time scale is obtained and provides the record with absolute ages, spanning from chrons C20n to C12r (Lutetian to Rupelian stages, ca. 43.0-31.0 Ma). Main differences with respect to the current chronostratigraphic scheme of the Eastern Ebro Basin include the age of the uppermost marine units. While earlier schemes attributed a Bartonian age to these units regarding its biostratigraphical contents, new results supports a Lower Priabonian age, yielding an interpolated age of ca. 36.0 Ma (within chron C16n.2n) for the continentalization process. This age is in concordance with a reinterpretation of earlier magnetostratigraphic data from the Western South Pyrenean Foreland Basin, and indicates that continentalization of the basin occurred as a rapid and isochronous event. The analysis of the observed sedimentation trends are used to evaluate the character of this process. Thus, contrasting sedimentation trends between the Western and Eastern sectors of the South Pyrenean foreland are proposed to indicate that basin closing preferentially affected those areas subjected to sediment bypass towards the ocean domain. Moreover, new results provide improved temporal constraints for the sediments of the Eocene Montserrat alluvial fan and fan-delta complex. Thus a Lutetian age is ascribed to the whole La Salut Formation and the age of the Montserrat Conglomerates spans from Upper Lutetian to Lower Priabonian. The new chronological framework is used to unravel the forcing controls on the sequential arrangement of the Montserrat area at different temporal scales, and also to revise the tectonosedimentary history. Obtained results show a correlation between (tectonic) subsidence and forelimb rotation measured on deformed strata of Montserrat. Furthermore, integration of subsidence curves from different sectors of the Eastern Ebro Basin allows estimating the variable contribution of tectonic loads from the two active basin margins: the Catalan Coastal Ranges and the Pyrenees. The results support the presence of a double flexure from Late Lutetian to Late Bartonian, associated to the two tectonically active margins. From Late Bartonian to Early Priabonian the homogenization of subsidence values is interpreted as the result of the coupling of the two sources of tectonic load. Finally, the obtained chronology contributes to the calibration of several biostratigraphic zonations to the geomagnetic polarity time scale. In the marine realm, the base of calcareous nannofossil Zone NP19-20 is pinned down to an older age than its currently accepted attribution, whereas the time span assigned to Zone NP18 is significantly reduced. A revised calibration of larger foraminifers indicates that Zone SBZ18, formerly assigned exclusively to Late Bartonian, extends its range to the earlymost Priabonian, being the Bartonian stage almost entirely represented by Zone SBZ17. A division of Zone SBZ18 into two subzones is also proposed. In the continental realm, the magnetostratigraphic record of the Eastern Ebro Basin yields accurate ages for the immediately pre- and post-Grand Coupure mammal fossil assemblages found in this basin. Thus, the Grande Coupure, a major terrestrial faunal turnover recorded in Eurasia associated with the overall climate shift at the Eocene-Oligocene transition, is found to occur with a maximum allowable lag of 0.5 Myr with respect to this boundary. Furthermore, results from this PhD-Thesis allow revisiting correlations for the controversial Eocene-Oligocene record of the Hampshire Basin (UK), and their implications for the calibration of the Mammal Paleogene reference levels MP18 to MP21. / Aquesta Tesi Doctoral presenta una nova cronologia del registre sedimentari Paleogen del marge SE del sector oriental de la Conca de l’Ebre. La cronologia obtinguda es basa en la integració d’un conjunt de sèries magnetostratigràfiques amb totes les dades biostratigràfiques dels registres marí i continental disponibles en aquest sector de la conca. L’establiment d’una correlació robusta amb l’escala de temps de polaritat geomagnètica proveeix al registre sedimentari Paleogen d’un marc cronològic amb edats absolutes que van des del cron C20n fins al cron C12r (ca. 43.0-31.0 Ma), és a dir, del Lutecià al Rupelià. Aquest nou marc cronològic proporciona les eines necessàries per a la quantificació i posterior comprensió de l’evolució tectonosedimentària dels marges adjacents a la Conca de l’Ebre. Finalment, la cronologia resultant de la present Tesi Doctoral contribueix a la calibració amb l’escala de temps geològic de les biozonacions de nanofòssil calcari i macroforaminífers (Shallow Benthic Zones), així com dels nivells de referència de mamífers paleògens europeus (European vertebrate Mammal Paleogene –MP- reference levels).

Le biome marin du Toarcien inférieur a subi une des crises les plus significatives de l'histoire de la Terre, qui a affecté les mers épicontinentales du globe. Ces bassins épicontinentaux sont également caractérisés par l'accumulation de grandes quantités de matière organique dans les sédiments de l'époque, ce qui a été interprété comme le résultat d'un Evénement Anoxique au Toarcien inférieur (T-OAE, ~183 Ma). Le nannoplancton calcaire, qui fait partie des organismes le plus sensibles aux conditions environnementales des eaux océaniques de surface, a été profondément affecté par cette crise et sa récupération se mit en place seulement à la fin du Toarcien inférieur. Si le T-OAE a été étudié en grand détail ces dernières années, la période de récupération est beaucoup moins bien connue. A ce stade, nous ne savons pas, notamment, si la récupération de la production carbonatée primaire est représentée par un épisode rapide ou par une suite d'événements (qui feraient partie d'un plus long processus) intervenus sur quelques millions d'années après le T-OAE. Pendant les perturbations environnementales qui ont eu lieu au Toarcien inférieur, des fluctuations importantes du niveau marin ont été interprétées ainsi que des variations de la température des eaux océaniques. Après le T-OAE, le niveau marin et les températures montrent des changements plus graduels pendant une grande partie du Toarcien supérieur-Aalénien inférieur et les niches écologiques occupées par le nannoplancton calcaire sont ré-établies. Ces conditions de relative stabilité sur le long terme (~10 Ma) sont idéales pour étudier les dynamiques de la communauté des nannofossiles calcaires et, notamment, comment les différents taxons réorganisent leurs relations synécologiques. Le Toarcien-Aalénien est une période clé dans l'évolution du nannoplancton calcaire, avec des nouveaux genres qui apparaissent. Les nannofossiles de cet intervalle restent relativement peu étudié dans le Bassin Lusitanien, malgré l'importance de cette région d'un point de vue paléocéanographique. En effet ce bassin, qui était à l'origine un rift avorté lié à l'ouverture de l'Atlantique, a permis les connections entre des masses d'eaux de provenance NW européenne et sud-téthysienne. C'est dans cette région que nous retrouvons donc des mélanges de taxons liés à des différentes provinces géographiques / At ~183 Ma when large amounts of organic matter was dumped onto the ocean beds (known as the Toarcian Oceanic Anoxic Event, T-OAE), the Early Toarcian marine biota experienced one of the most important biological crises in Earth history. Calcareous nannoplankton was deeply affected and started only to recover from the end of the Early Toarcian. After the T-OAE, as phytoplankton communities dwelling the oceans photic layer recover from the previous disturbing conditions, the ecological niches once occupied by calcareous nannoplankton are again replenished. Located in the westernmost part of the Tethyan ocean, the Lusitanian Basin acted as a seaway between the NW Tethys and the Mediterranean Tethys provinces, therefore been actively influenced by these two different water masses. Hence such a region stands as the perfect spot to study the calcareous nannoplankton community, as its fossil remains bears species typical of both provinces. In order to appraise the nannoplankton demise and subsequent recovery, absolute and relative abundances of nannofossils were determined from pelagic marl-limestone couplets from three sections of the Lusitanian Basin. Also brachiopods shells were investigated for stable carbon and oxygen isotopes analysis. In order to independently assess the morphologic evolution of Lotharingius coccoliths, a Toarcian section from south France was studied. Different statistic methodologies were used throughout this work, in order to screen for robust and significant information from the numerous datasets that were built / Há cerca de 183 milhões de anos atrás, a biota marinha sofreu uma das mais importantes crises biológicas na história do planeta, quando grandes quantidades de matéria orgânica foram depositadas nos fundos oceânicos. Este episódio que teve lugar durante o Toarciano, resultou de um Evento Anóxico Oceânico (T-OAE), e afectou os mares epicontinentais à escala global. O nanoplâncton calcário, um grupo de organismos extremamente sensível às variações nas condições ambientais que têm lugar na camada superficial das massas de água, foi profundamente afectado. Foi somente no final do Toarciano Inferior que a sua recuperação se iniciou. Apesar de já muito se ter escrito sobre o T-OAE, a previsível recuperação deste grupo nunca foi sistemática nem detalhadamente estudada. Até hoje, não se sabia ainda se esta recuperação teria sido relativamente rápida, ou resultado de um processo lento e gradual que teria durado milhões de anos. Durante o Toarciano Inferior, quando as condições ambientais eram extremamente instáveis, ocorreram importantes e drásticas oscilações na temperatura e no nível médio dos oceanos. Após o T-OAE e durante todo o Toarciano e Aaleniano Inferior, as oscilações do nível médio dos oceanos e de temperatura são bastante mais suaves. À medida que a comunidade fitoplanctónica instalada na zona fótica recupera das condições extremas anteriores, os nichos ecológicos antes ocupados por nanoplâncton calcário, começam novamente a ser preenchidos. Apesar das prolongadas e suaves variações abióticas, é num ambiente então mais estável, que melhor se pode observar a evolução deste grupo, e de que forma as suas relações sinecológicas se alteraram ao longo de aproximadamente 10 milhões de anos. Apesar de ser considerado como um período onde a comunidade nanoplanctónica sofreu importantes alterações, nada se sabe em concreto que alterações foram essas que tiveram lugar após o TOAE num local tão estratégico como a Bacia Lusitânica. Situada na extremidade Oeste do Tétis e fazendo parte de um rift originado pela abertura do Atlântico, a Bacia Lusitânica actuou como um corredor que ligava livremente as massas de água das províncias mediterrânica e NW do Tétis, sendo por estas, activamente influenciada. Por essa razão, tal situação geográfica constitui um local excepcional para se estudar a comunidade de nanoplâncton calcário, uma vez que o seu registo fóssil compreende espécies típicas destas duas províncias do Tétis