Les granites peralumineux sont les acteurs principaux de la différentiation de la croûte continentale et représentent un enjeu sociétal important car ils sont associés à de nombreux gisements métallifères. Dans la chaîne hercynienne européenne, la majorité des gisements hydrothermaux d'uranium (filons ou épisyenites) sont associés à des leucogranites peralumineux d'âge tardi-carbonifère. Ainsi dans le Massif armoricain, 20000 t d'uranium (U) (~20% de la production historique française), ont été extraites des gisements associés aux leucogranites de Mortagne, Pontivy et Guérande. L'objectif de ce travail est de mieux comprendre le cycle de l'uranium dans la chaîne hercynienne armoricaine depuis la source des leucogranites, leur évolution et leur mise en place dans la croûte supérieure jusqu'à leur lessivage par des fluides, la formation des gisements puis leur exhumation en sub-surface. Dans ce but, des données pétro-géochimiques, géochronologiques et thermochronologiques ont été obtenues sur les leucogranites de Guérande, Pontivy et leurs gisements d'uranium associés. Les leucogranites de Guérande et de Pontivy se sont mis en place, respectivement, à ca. 310 Ma dans une zone de déformation extensive dans le domaine interne de la chaîne et ca. 315 Ma dans le domaine externe le long du cisaillement sud armoricain (CSA), une faille décrochante d'échelle lithosphérique. Les deux leucogranites sont issus d'un faible taux de fusion partielle de métasédiments détritiques et d'orthogneiss peralumineux, la fusion de ces derniers ayant vraisemblablement joué un rôle majeur dans la richesse en uranium des leucogranites. La fusion de la croûte continentale dans la zone interne de la chaîne a été induite par l'extension tardi-orogénique alors que la fusion de la croûte mais aussi du manteau dans la zone externe était probablement contrôlée par une déformation décrochante diffuse. La cristallisation d'oxydes d'uranium magmatiques dans les facies les plus évolués des leucogranites au moment de leur mise en place a été vraisemblablement rendue possible grâce à l'action combinée de la cristallisation fractionnée et d'une activité magmatique-hydrothermale diffuse. De ca. 300 Ma à 270 Ma, une activité tectonique fragile le long du CSA et des détachements a permis l'infiltration de fluides météoriques oxydants en profondeur induisant la mise en solution des oxydes d'uranium des leucogranites. Ensuite, les fluides ont précipité leur U dans des failles ou des fentes de tension à proximité du contact avec des lithologies sédimentaires avec un caractère réducteur variable. Les leucogranites étaient toujours en profondeur à des températures supérieures à 120°C au moment de la formation des gisements et leur exhumation en sub-surface n'est pas enregistrée avant le Trias ou le Jurassique. Ce modèle métallogénique n'est probablement pas exclusif au Massif armoricain car la période de formation des gisements d'U dans la région entre 300 et 270 Ma est la même que dans l'ensemble de la chaîne hercynienne européenne. / Peraluminous leucogranites are the principal actors for the differentiation of the continental crust and play an important economic role because they are commonly associated with significant metalliferous deposits. Most hydrothermal uranium (U) deposits (vein or episyenite types) from the European Hercynian belt are spatially associated with Carboniferous peraluminous leucogranites and in the French Armorican Massif (western part of the European Hercynian belt) 20000 t of U (~20 % of the French production) were extracted from the deposits associated with the Mortagne, Pontivy and Guérande leucogranites. The objective of this work is to improve our knowledge about the U cycle in the Armorican Hercynian Belt from the leucogranites sources, their evolution and emplacement in the upper crust to U leaching, deposit formation and leucogranites exhumation at the subsurface level. For that purpose, petro-geochemical, geochronological and thermochronological data were obtained on the Guérande and Pontivy leucogranites as well as their spatially associated U deposits. The Guérande leucogranite was emplaced ca. 310 Ma ago in an extensional deformation zone in the internal domain of the belt whereas the Pontivy leucogranite was emplaced ca. 315 Ma ago in the external domain along the South Armorican Shear Zone (SASZ), a lithospheric scale wrench fault. Both leucogranites were formed by a low degree of partial melting of detrital metasediments and peraluminous orthogneisses; the fusion of the latter probably played a major role in the generation of U rich leucogranites. Partial melting of the crust in the internal zone of the belt was triggered by late orogenic extension whereas partial melting of the crust but also the mantle in the external zone was likely controlled by pervasive wrenching. The crystallization of magmatic uranium oxides in the most evolved leucogranitic facies was induced by fractional crystallization and probably enhanced by magmatic-hydrothermal processes. From ca. 300 to 270 Ma, a fragile tectonic activity along detachments and the SASZ, allowed for the infiltration at depth of meteoric oxidizing fluids, able to dissolve magmatic uranium oxides in the leucogranites. These fluids have then precipitated their U in faults or tension gashes close to the contact with sediments having a variable reducing character. The leucogranites were at depth above 120°c during the formation of U deposits and the exhumation of these intrusions did not occur before the Trias or the Jurassic. The proposed metallogenic model is likely not exclusive to the Armorican Massif as the timing of U deposits formation in the region from ca. 300 to 270 Ma is similar to the main U mineralizing event in the whole European Hercynian belt.

La zone de déformation compressive des Brooks Range et des British-Barn située entre l’Alaska (Etats-Unis) et la région du Nord Yukon (Canada), en position arrière-arc, se développe dans un contexte cinématique et géodynamique depuis longtemps débattu. L’histoire tectonique du bloc continental Arctique d’Alaska, situé dans l’avant-pays de Brooks Range, est diversement interprétée dans les reconstructions de l’ouverture du bassin canadien. La chaîne de Brooks se développe à partir du Crétacé inférieur et sa mise en place se poursuit au Cénozoïque. Mieux contraindre son histoire d’exhumation, en relation avec le raccourcissement est essentiel dans cette région arctique où la cinématique des plaques, associée à l’ouverture du bassin canadien au Nord, fait l'objet de nombreux modèles géodynamiques controversés. La relation avec la subduction active Pacifique au Sud et les grands décrochements en arrière de la subduction fait de cette chaîne, en position arrière arc, une zone-clef pour affiner les reconstructions géodynamiques régionales et notre compréhension des processus orogéniques. Si le lien n'est pas établi entre la déformation mise en jeu dans cette subduction au Mésozoïque et la déformation dans la chaîne de Books, ce lien est en revanche assez bien documenté à l'heure actuelle. Il est donc légitime d'appréhender les événements sud-alaskans dans l'étude de cette chaîne de Brooks. La croissance de la chaîne au Cénozoïque est également mal comprise. Or, il s’agit d’un exemple quasi-unique de chaîne en milieu arctique active durant le Cénozoïque et qui a donc potentiellement enregistré des bouleversements climatiques majeurs, en l'occurrence depuis l‘optimum climatique à la transition Paléocène-Eocène, le refroidissement Oligocène jusqu’à la mise en place de glaciers et de la calotte nord-américaine au Quaternaire. Cet orogène est donc clef pour étudier voire quantifier l'impact du climat sur la construction topographique nord-alaskane. Ce travail a combiné une étude thermochronométrique basse-température multidatation (FT, (U-Th)/He) dans les massifs granitiques et dans les sédiments, qui ont fait l'objet de modélisation thermo-cinématiques via Pecube, dans le but de contraindre la construction orogénique depuis 100 Ma jusqu’à l’actuel. En parallèle, une approche structurale de terrain (Nord Yukon et Brooks Range) et l'analyse de données de subsurface ont été menées. Les données thermochronologiques, couplées à des analyses thermométriques RSCM et de la modélisation thermique soulignent la mise en place de reliefs au Crétacé supérieur avec une exhumation modérée (0.2 km/Ma) qui se poursuit jusqu'à la fin de l'Eocène, où les taux d'exhumation dans les chaînes de Brooks et British-Barn sont clairemement orogéniques (1.25-1.29km/Ma), et associés à la migration de la déformation vers les bassins adjacents. Ce travail souligne une migration de la déformation du SO vers le NE. Dans les deux segments de la chaîne un événement d'exhumation distinct est identifié à l'Oligocène : celui-ci est clairement associé dans la partie interne de la chaîne de Brooks à la mise en place hors-séquence d'un duplex crustal ; et associé à la migration de la déformation compressive en mer au large de la chaîne de British-Barn. Si le calendrier tectonique est semblable dans ces deux zones d'étude, il existe une différence majeure dans le style de déformation entre ces deux régions. Le front de déformation semble beaucoup plus éloigné de la chaîne et les failles beaucoup plus espacées dans la partie canadienne, éloignement et espacement probablement liés à l’épaisseur de sédiments syn-sédimentaires présents dans le bassin... / The kinematics and geodynamics associated with the compressional deformation in the Brooks Range and British-Barn Mountains, respectively in Alaska (USA) and North Yukon (Canada), in a back-arc setting has long been debated. In particular, the tectonic history of the Arctic Alaska continental block located in the foreland of the Brooks Range has been diversely interpreted in the plate reconstructions proposed for the Canadian basin. The Brooks Range mountain chain develops from the Lower Cretaceous to the Cenozoic. Constraining its exhumational history and its link with shortening evolution is essential in this arctic area where plate tectonics, associated to the Canadian basin opening in the North, has led to controversial geodynamic models. Tectonic coupling with the active Pacific subduction in the south as well as major seismogenic strike-slip faulting make this orogen a key area where to refine the regional plate reconstructions and understanding of orogenic processes. The Cenozoic evolution of the Brooks Mountains is poorly understood although it is a nearly unique example of arctic orogen, which have potentially recorded major climate changes like Paleocene-Eocene Thermal Maximum, the Oligocene cooling and Quaternary glaciations. This orogen is a key to study and quantify the climate impact on the north-alaskan topographic growth. This study combined low-temperature thermochronometry (FT, U-Th/He) on granitic and sedimentary rocks, which were thermo-kinematically modeled using Pecube in order to define the orogenic evolution of this arctic region since 100 Ma. In parallel, a field-based structural study (North Yukon and Brooks Range) was combined with the analysis of subsurface data. Thermochronological data, coupled to thermometric RSCM analyses and thermal modeling first define a slow exhumation period (0.2 km/Ma) from Upper Cretaceous up to the Eocene. With the Eocene, exhumation rates drastically increased to reach 1.25-1.29km/Ma as the deformation also migrates from SW toward NE. In both alaskan and canadian parts of mountains ranges a clear Oligocene exhumational event is identified. This event is linked to out-of-sequence crustal duplexing in the internal part of the range in the Brooks Range, contemporaneous with the propagation of deformation offshore, along British and Barn Mountains...

Ce travail de thèse concerne une transversale complète des Pyrénées centro-occidentales, où on a combiné la thermochronologie basse température (traces de fission sur apatites, TFA) avec une analyse structurale détaillée pour décrire les mouvements verticaux associés à l'évolution du système chevauchant, et pour déterminer l'influence de ce dernier sur le cycle sédimentation/enfouissement/exhumation des dépôts synorogéniques du bassin d'avant-chaine sud (bassins de Jaca et Ainsa). L'analyse TFA complète les données déjà publiées dans la Zone Axiale et la Zone Nord-Pyrénéenne, et constitue la première étude de ce genre dans un bassin d'avant-chaîne pyrénéen. Les données TFA sur la transversale du bassin sud-pyrénéen montrent une diminution vers le sud du degré d'effacement des traces de fission, traduisant la diminution vers le sud de la quantité d'enfouissement, supérieure à 5 km au nord et inférieure à 3 km au sud dans l'hypothèse un géotherme de 25°.km-1. Le contexte géologique montre que l'enfouissement est principalement lié à l'accumulation des dépôts synorogéniques. Les données TFA de la partie nord du bassin montrent un refroidissement d'âge Oligocène supérieur-Miocène inferieur (moyen). Par ailleurs, une nouvelle interprétation de profils de sismiques réflexion dans le bassin de Jaca montre que le chevauchement d'Oturia s'enracine dans le chevauchement de socle de Bielsa, responsable de l'exhumation tectonique hors-séquence du bord sud de la Zone Axiale au Miocène inférieur (-moyen) (Jolivet et al., 2007). Ces résultats attestent donc de l'exhumation tectonique hors-séquence au Miocène inférieur (Burdigalien- ?Langhien) de la partie nord du bassin d'avant-chaine sud-pyrénéen. Des données TFA obtenues dans la Zone Axiale et la Zone Nord-Pyrénéenne confirment la migration générale vers le sud du système chevauchant, et mettent également en évidence la réactivation tectonique hors-séquence du bord nord de la Zone Axiale à l'Oligocène terminal-Miocène inférieur. L'ensemble de ces résultats atteste donc de la réactivation en « pop-up » de la parties interne des Pyrénées centre-ouest à l'Oligocène supérieur-Miocène inférieur (Burdigalien- ?Langhien), postérieurement au scellement du front sud-pyrénéen (Aquitanien- ?Burdigalien) classiquement considéré comme marquant la fin de la compression pyrénéenne. Ces données nous ont permis de proposer un nouveau modèle d'évolution crustale des Pyrénées centro-occidentales en 3 grandes étapes : (i) du Crétacé supérieur à l'Eocène moyen, le prisme est caractérisé par une absence de relief, en lien avec l'inversion de structures extensives crétacées conduisant à l'accrétion de petites écailles crustales ; (ii) la période Eocène supérieur-Oligocène correspond à la collision continentale proprement dite, et est marquée par la création d'importants reliefs associés à l'accrétion d'épaisses unités crustales ; (iii) au Miocène inférieur, la partie interne du prisme pyrénéen est réactivée. / In this work on a complete transect of the west-central Pyrenees, we combine low temperature thermochronology (apatite fission tracks, AFT) with a detailed structural analysis to describe vertical movements related to the thrusting system evolution, and to determine the influence of the latter on the sedimentation/burial/exhumation cycle of the synorogenic deposits of the southern foreland basin (Jaca and Ainsa basins). AFT analysis from a transect of the south-Pyrenean basin show the southward decrease of the fission track reset level from the southern edge of the Axial Zone to the South-Pyrenean frontal thrust, implying the southwards decrease of the burial amount from more than 5km in the north to less than 3km in the south assuming an average geothermal gradient of 25°C.km-1. The structural setting of the Jaca basin attests that the burial of the synorogenic sediments was mainly due to the sedimentary accumulation. AFT data from the northern part of the basin display a late Oligocene-early (middle) Miocene cooling event. New interpretation of industrial seismic reflection profiles across the Jaca basin suggests that the Oturia thrust is rooted in the Bielsa basement thrust, responsible for the early (-middle) Miocene out-of-sequence tectonic reactivation of the southern flank of the Axial Zone (Jolivet et al., 2007). These results reveal a lower Miocene (Burdigalian -?Langhian) out-of-sequence episode of tectonic activity of the interior of the south-Pyrenean foreland basin. AFT data from the Axial Zone and the North-Pyrenean Zone confirm the general southward migration of the thrusting system, and also bring evidence of the late Oligocene-lower Miocene out-of-sequence tectonic reactivation of the northern flank of the Axial Zone. All these results attest of a late Oligocene-lower Miocene (Burdigalian-?Langhian) 'pop-up' reactivation of the inner part of the west-central Pyrenees, younger than the sealing of the south-Pyrenean front (Aquitanian-?Burdigalian) which is classically considered to mark the end of the Pyrenean compression. These results lead us to propose a new crustal scale evolution model of the west-central Pyrenees in 3 stages: (i) From the Late Cretaceous to the middle Eocene, the orogenic prism is characterised by the absence of relief, related to the inversion of Cretaceous extensional structures leading to the accretion of thin crustal units; (ii) The late Eocene-Oligocene stage corresponds to the continental collision, marke d by the creation of important relief associated with the accretion of thick crustal units; (iii) During the early Miocene, the inner part of the Pyrenean wedge is tectonically reactivated.

Deux questions scientifiques critiques sont adressées dans cette thèse présentées comme suit. ( 1 ) L’évolution mésozoïque du bassin d’avant-pays dans les piémonts nord et sud du Tian Shan. ( 2 ) L’évolution au Cénozoïque précoce du soulèvement du Tian Shan. Dans le chapitre 1, l'évolution du nord Tian Shan est étudiée par datation U/Pb (LA- ICP-MS) de zircons détritiques sur 14 échantillons de grès d'une série continue d’âge fin Paléozoïque à Quaternaire dans la marge sud du bassin de Junggar (région de Manasi). Dans le chapitre 2, l'évolution encore mal contrainte entre le Mésozoïque et le début du Cénozoïque de la marge sud-ouest du Tian Shan est étudiée en utilisant les datations U/Pb ( LA- ICP-MS ) sur zircons détritiques et les traces de fission sur apatites détritiques. Dans le chapitre 3, nous présentons une étude magnétostratigraphique détaillée de la zone Ulugqat au sud-ouest du Tian Shan, dans le but d'améliorer la compréhension de son soulèvement et de l'histoire de la déformation de la région au cours du Cénozoïque. Ce travail à permis de montrer que l'érosion du paléo-Tian Shan commencée au Trias moyen s’est traduite par le pénéplanation générale au Mésozoïque du Tian Shan qui était dominé par un système de drainage large pendant une longue période de quiescence tectonique. Le piémont nord du Tian Shan était caractérisé par un bassin en subsidence thermique post- extensive avec peu d'activité tectonique, et le piémont sud a également connu un aplanissement général de la topographie. Au cours du début du Jurassique, du Crétacé inférieur et du Crétacé supérieur, trois inversions tectoniques mineures sont identifiées avec des ajustements du bassin d’avant-pays du Tian Shan. Ces inversions peuvent correspondre respectivement à l’accrétion des terrains Cimmérien, de Lhassa, et du Kohistan-Dras à la limite sud de la plaque eurasienne. Les données U-Pb sur zircons détritiques et les données traces de fission sur apatite indiquent une première réorganisation du bassin à la fin du Crétacé – début du tertiaire, contemporaine d’une réactivation de l’érosion le long du piémont sud du Tian Shan. Nous avons interprété cette réactivation fin Crétacé – début Paléogène du Tian Shan sud à la réponse initiale des effets lointains de la collision Inde-Eurasie. Pendant le reste du Cénozoïque, la principale réactivation du Tian Shan est initiée fin Oligocène – début Miocène. Cela est attesté dans le piémont nord du Tian Shan par nos données U-Pb sur zircons détritiques et dans le piémont sud du Tian Shan par les données traces de fission sur apatite suggérant des chevauchements entre 18 et 16 Ma, par les résultats magnétostratigraphiques révélant une importante lacune de sédimentation oligocène ainsi que l’augmentation des taux d’accumulation à ~ 18.5 Ma. / Two critical scientific issues are adressed in the présent thesis as follows. (1) Mesozoic basin-range relationship in the northern and southern piedmonts of the Tian Shan. (2) Spatio-temporal differences in the Early Cenozoic uplift of the Tian Shan. In chapter 1, the évolution of the northern Tian Shan is investigated through U/Pb (LA-ICP-MS) dating of detrital zircons from 14 sandstone samples from a continuous series ranging in age from latest Palaeozoic to Quaternary in the southern margin of the Junggar Basin (Manasi area). In chapter 2, the still poorly constrained Mezosoic to early Cenozoic evolution of the southwestern Tian Shan piedmont is investigated using U/Pb (LA-ICP-MS) dating of detrital zircons and fission track analysis on detrital apatites. In chapter 3, we present a detailed magnetostratigraphic study from the Ulugqat area in piedmont of the Southwest Tian Shan, in order to improve understanding of the uplift and deformation history of the Southwest Tian Shan during the Cenozoic. This work enabled to show that erosion of the Paleo-Tian Shan initiated in the Middle Triassic results in the general peneplanation of the Mesozoic Tian Shan dominated by a wide drainage system and long-lasting tectonic quiescence. The northern piedmont of the Tian Shan was characterized by a post-extensional thermally subsiding basin without much tectonic activity, and the southern piedmont also experienced a general flattening of topography. During the Early Jurassic, Early Cretaceous and Late Cretaceous, three identified minor tectonic inversions and adjustments of basin-range pattern in the Tian Shan, may potentially correspond respectively to the accretions of Cimmerian, Lhasa, and Kohistan-Dras in the southern margin of the Eurasian plate. Detrital zircon U-Pb and apatite fission-track data indicate an initial late Cretaceous – Early Tertiary basin reorganization and coeval renewed erosion along the southern Tian Shan piedmont. We interpreted this late Cretacesou to Paleogene activity in STS as the initial response of the distant effects of India-Eurasia collision as previously argued. During the Late Cenozoic, the major reactivation of the Tian Shan initiated around the Late Oligocene-Early Miocene times. This is evidenced mainly from the detrital zircon U-Pb geochronology in the northern piedmont of the Tian Shan, the apatite fission-track data suggesting a possible activation of the Talas Fergana Fault between 18 and 16 Ma, the major Oligocene depositional hiatus and conspicuous increase in accumulation rates at ~ 18.5 Ma revealed by the magnetostratigraphic results in the southern piedmont of the Tian Shan.

La dynamique des cratons reste, encore actuellement, énigmatique dans la mesure où ceux-ci sont souvent considérés comme des domaines stables à l’échelle des temps géologiques. Dans ce travail, nous avons reconstitué l’évolution d’un des plus grands cratons, le Craton Ouest Africain. Nous nous sommes également penchés sur l’étude de ses bordures nord et ouest (Anti-Atlas et marge atlantique respectivement). Cette étude utilise les méthodes de thermochronologie basse-température (traces de fission et (U-Th-Sm)/He sur apatite) ainsi que la géologie structurale. Le choix de ce craton est justifié par les multiples contextes géologiques dont témoignent ses bordures au cours du Phanérozoïque (plateforme, avant-pays distal, marge passive). Ces contextes variés au cours du temps en font donc une cible idéale pour évaluer l’influence des diverses forces susceptibles d’affecter le craton.Tout d’abord, suite à une subsidence importante au cours du Paléozoïque, le craton enregistre un refroidissement important entre le Jurassique supérieur et le Crétacé inférieur, postérieurement à l’ouverture de l’Atlantique Central. Cet événement n’est pas directement lié aux seuls processus affectant les marges passives puisque non seulement la marge est affectée, mais aussi l’intérieur du craton (jusque 800 km à l’intérieur des terres) et le domaine mobile non-cratonique au Nord. Ce refroidissement traduit une phase d’exhumation kilométrique qui permet alors le dépôt d’une épaisse séquence détritique sur la plateforme saharienne. L’hypothèse d’un raccourcissement comme explication n’est pas valide et l’hypothèse d’une anomalie thermique mantellique à cette époque rend mieux compte de cet événement d’érosion majeur. L’hypothèse thermique possède un autre avantage : celui de rendre compte du réchauffement qui suivit à l’Apto-Albien et au début du Crétacé supérieur, à la fois par le craton mais aussi par ses bordures, par le biais de la subsidence thermique.Deuxièmement, à partir du Crétacé supérieur, la tendance générale est au refroidissement dans toute la région étudiée, synchrone avec l’initiation de la convergence Afrique/Europe. La chaîne du Haut Atlas au Maroc représente à ce moment un témoin privilégié des déformations se produisant pendant le Cénozoïque. Nous avons déterminé un calendrier tectonique précis dans l’avant-pays méridional de la chaîne, afin d’avoir un point de comparaison avec l’enregistrement cratonique. Ainsi, une première phase tectonique se déroule à l’Eocène supérieur. Celle-ci fait écho à un événement de déformation de plus grande échelle qui affecte toute le craton, résultant sans doute d’une réorganisation de grande ampleur dans la dynamique de la convergence. La phase récente Plio-Quaternaire est bien décrite à l’échelle de l’Afrique du Nord dans la chaîne Atlasique, mais pourrait s’avérer trop récente pour pouvoir être décelée par nos thermochronomètres à l’intérieur du domaine cratonique. Enfin, une phase de soulèvement spécifique au domaine atlasique marocain est enregistrée pendant le Miocène inférieur-moyen et met en place des nappes dans la chaîne. Les thermochronomètres basse-température ne la détectent pas à l’intérieur du craton, et elle pourrait donc être géographiquement restreinte au domaine atlasique.Ce travail a démontré que l’absence de sédiments au cours du Méso-Cénozoïque, qui en première approche font de ce craton une zone dite « stable », occulte une réalité géologique autre, faite de la succession de plusieurs phases épeirogéniques. Une évaluation des processus à l’œuvre permet de proposer que les phénomènes mantelliques ainsi que les transferts de contraintes sont des acteurs majeurs à l’origine de ces mouvements. Néanmoins, la juste contribution de chacun de ces processus nécessite encore un travail approfondi. / The dynamic evolution of cratonic domains remains enigmatic as they are usually considered as stable through geological times. In this work, we unraveled the evolution of one of the largest cratonic area, the West African Craton (WAC), and its north and west boundaries (Anti-Atlas and Atlantic passive margin, respectively), through low-temperature thermochronology (apatite fission-track and (U-Th)/He thermochronology) and structural geology. The WAC was studied since its boundaries witnessed many different geological settings (platform, distal foreland, passive margin) during the Phanerozoic, making it a good candidate to evaluate the various driving forces acting on the craton.First, after a continuous Paleozoic subsidence, the craton records the most important cooling event between Late Jurassic and Early Cretaceous, postdating the onset of the Central Atlantic Ocean spreading. This event is unrelated to the sole passive margin in itself and affected both the craton (up to 800 km inland) and the mobile boundary in the north (Anti-Atlas and High Atlas). It represents kilometer-scale erosion that led to the deposition of thick detrital formations, the red beds, across the whole Saharan platform. This event is not characterized by shortening and is better explained through a mantle-related thermal anomaly during this exhumation. The thermal hypothesis explains the subsequent thermal subsidence undergone by the craton and its north boundary during the Aptian-Albian and the early stages of the Late Cretaceous.Second, from Late Cretaceous onward, dominant cooling trend has imprinted the thermal histories of the studied region, coevally with the onset of the Africa/Europe convergence.The High Atlas belt in Morocco is an accurate witness of the deformations occurring during Cenozoic times. We determined the precise tectonic schedule in the southern foreland of the belt and compared this evolution with the cratonic one. We show that the first Eocene tectonic event echoes to a major craton-scale deformation and results probably from a significant geodynamic change in the convergence zone. The Pliocene-Quaternary phase, well known at the North African scale, is only recorded in the Atlas belt, but might be too recent to have significantly imprinted the thermochronological record inside the craton. Finally, another uplift specific to the Moroccan Atlas Belt during Early to Middle Miocene led to the emplacement of tectonic nappes. This event is not recorded by LTT on the craton and may be restricted to its mobile boundary.This work demonstrates that, despite the lack of Mesozoic-Cenozoic sediment record that may advocate for a stable geological history, the West African Craton suffered significant epeirogenies during this period. Deep seated processes as well as stress transmission prove to be good candidates to account for these cratonic motions, although further work is needed to unravel the exact contribution of these various processes.

Ce manuscrit concerne l'analyse tectonique et géomorphologique du système de failles de Longriba (LFS), localisé à l'Est du plateau tibétain à environ 200 km au Nord-ouest de la chaîne des Longmen Shan. Le LFS est constitué de deux zones de failles décrochantes dextres, parallèles et d'orientation N55°E : la faille de Longriqu, au Nord, et la faille de Maoergai, au Sud. Le rôle géodynamique de ce système est primordial puisqu'il accommode 5 ± 1 mm/an de la composante décrochante induite par la convergence oblique du bloc Aba, elle-même liée à la collision Inde-Asie. De plus, le LFS partitionne la déformation de la marge Est tibétaine; les structures des Longmen Shan étant essentiellement chevauchantes. Cependant l'histoire long-terme du LFS est mal contrainte. L'objectif de cette thèse est donc d'apporter des informations spatio-temporelles sur l'activité du système à l'échelle du Cénozoïque. Pour cela trois études ont été réalisées. La première a permis de mieux contraindre le comportement sismogénique des deux zones de failles à l'aide d'images satellites de basse (90m) et très haute résolution (50cm). L'analyse des déplacements cumulés le long de la faille de Maoergai a permis de proposer que celle-ci était active vers ~15Ma. La seconde étude a mis en évidence un contrôle du système sur la répartition des taux de dénudation au travers de la marge Est tibétaine à l'échelle de l'Holocène. Enfin, les données de thermochronologie basse température suggèrent que la faille de Maoergai a accommodé un mouvement vertical vers ~10Ma. Ce mouvement est probablement lié au rebond isostatique de la marge, découplé du mouvement décrochant qu'elle accommode à la même période. / This manuscript concerns the tectonic and geomorphic analysis of the Longriba fault system (LFS), located in the eastern Tibetan plateau at about 200 km north-west of the Longmen Shan. The LFS consists of two dextral strike-slip fault zones, parallel and N55 °-trending: the Longriqu fault to the north and the Maoergai fault the south. The geodynamic role of the system is essential as accommodates 5 ± 1 mm / year of the slip component induced by the oblique convergence of the Aba block, itself linked to the India-Asia collision. In addition, the LFS partitions the deformation of the east Tibetan margin; the structures of the Longmen Shan are mainly thrust faults. However the long-term history of LFS is poorly constrained. The objective of this thesis is to bring spatial and temporal information on system activity throughout the Cenozoic. To do so, three studies were performed. The first led to better constrain the seismogenic behavior of the two fault zones with low resolution (90m) and very high resolution satellite images (50cm). The analysis of cumulative displacements along the Maoergai fault allowed to propose that it was active at ~ 15 Ma. The second study showed that the system controls the distribution of the denudation rates over the EastTibetan margin throughout the Holocene. Finally, the low-temperature thermochronology data suggest that, in particular, the Maoergai fault has accommodated a vertical movement at ~ 10 Ma. This movement is probably related to the isostatic rebound of the margin, decoupled from the strike-slip movement it accommodates at the same period.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O relevo da Serra da Bocaina revela o forte controle das estruturas dúcteis e rúpteis relacionadas à Faixa Ribeira gerada na Orogênese Brasiliana (ca. 790-480 Ma) e às reativações mesozóica-cenozóicas. As rochas são agrupadas em 4 terrenos tectônicos colados nas etapas colisionais brasilianas, que formaram as estruturas mais penetrativas: foliação com mergulho para NW, zonas de cisalhamento dúcteis NESW e dobras. Zonas de cisalhamento rúptil-dúcteis NW marcam o colapso orogênico. A abertura do Atlântico Sul (ca. 135-120 Ma) é registrada pelos enxames de diques toleíticos NNE e ENE, em parte condicionados pelas estruturas brasilianas. No Planalto da Bocaina uma idade de traço de fissão em apatita (TFA) de ca. 145 Ma data o resfriamento ainda da fase pré-rifte do Gondwana. O soerguimento da margem continental na fase rifte pode ter alçado este nível para fora da zona de apagamento parcial do TFA. A reativação neocretácea é datada pelo TFA (ca. 85 Ma) na costa e na escarpa atlântica, indicando novo pulso de denudação e soerguimento da margem continental. Isto também concorda com o extenso aporte de sedimentação siliciclástica na Bacia de Santos. No Paleógeno, a formação dos Riftes Continentais do Sudeste Brasileiro (RCSB) gerou a reativação das estruturas dúcteis NE da Faixa Ribeira, falhas e fraturas NW, E-W, além de fraturas NE na Baía da Ilha Grande. O contato tectônico entre os Terrenos Paraíba do Sul e Embu é a principal zona reativada na Serra da Bocaina. Idades TFA (ca. 55 Ma) registram o estágio inicial do RCSB, que provocou o rebaixamento do nível de base e a formação de uma escarpa no interior. A Serra da Bocaina parece constituir uma região elevada desde a formação da Cordilheira Ribeira, incrementada pelos soerguimentos das fases rifte e pós-rifte do Atlântico e do RCSB. Estes eventos tectônicos que elevaram a Serra da Bocaina, também geraram as estruturas que conduzem sua denudação. Neste contexto, destaca-se o par de estruturas NE (foliação e zonas de cisalhamento reativadas ou não) e NW (fraturas e falhas), as mais freqüentes, que orienta a rede de drenagem, os níveis de base locais (knickpoints) e as formas côncavas das encostas (cabeceiras de canais). Diques toleíticos também conduzem a dissecação dos vales fluviais. Por outro lado, granitos e ortognaisses que sustentam as elevações e segmentos de escarpas mostram o papel da erosão diferencial em rochas mais resistentes. A denudação do Planalto da Bocaina e o recuo de suas escarpas (atlântica e interior) são regulados por diferentes níveis de base (p.ex. nível do mar, rio Paraíba do Sul no RCSB, diversos knickpoints), sensíveis aos eventos de reativações tectônicas (soerguimento), variações eustáticas e à erosão diferencial. Os pulsos erosivos vêm dissecando de modo diferencial os vales suspensos do planalto, através da incisão fluvial e reativação das cabeceiras de canais, que avançam sobre as encostas promovendo a quebra dos divisores e capturas de drenagens. Este processo rebaixamento de relevo parece levar à formação das superfícies colinosas que ocorrem em diferentes níveis topográficos. As idades TFA antigas indicam baixas taxas de denudação na porção mais elevada do Planalto da Bocaina, o que contrasta com as altas taxas da região costeira. Este caráter diferencial da denudação condicionada pelo substrato geológico e pelos eventos de soerguimento, vem preservando antigas paisagens no Planalto da Bocaina. No outro extremo, a denudação propagada pelo recuo das duas escarpas vem degradando as bordas e introduzindo a dissecação no interior do planalto. As duas escarpas geradas por eventos riftes distintos vêm se ajustando ao controle das rochas e estruturas da Faixa Ribeira. / The Bocaina Ridge landscape is strongly controlled by both ductile and brittle structures related to the Ribeira Belt (Brasiliano Orogeny ca. 790-480Ma) and also to the mesozoic-cenozoic reactivations. The rocks were subdivided in four tectonic terrains accreted in the brasiliano collisional stages. The most prominent structures related to these collisions are: NW dipping foliation, NE-SW ductile shear zones, and folds. NW ductile-brittle shear zones represent the orogenic collapse stage. The South Atlantic opening (ca.135-120 Ma) is registered in NNE and ENE tholeitic dike swarms, partly conditioned by brasiliano structures. In the Bocaina Plateau one apatite fission track age (AFT) of ca.145Ma represents pre-rift Gondwana cooling. The continental margin uplift associated to the rift phase might have raised this level out of the AFT partial annealing zone. Neocretaceous reactivation (ca. 85Ma) was AFT dated both in the coast and the atlantic scarp, pointing out to a newer continental margin denudation and uplift pulse. This reactivation is in accordance with the Santos basin significant siliciclastic sedimentation. In paleogene times, the Southeastern Brazil Continental Rift System (SBCR) development was responsible for: the reactivation of the Ribeira Belt NE ductile structures, NW and E-W faulting and fracturing, and NE fracturing in Ilha Grande Bay. The tectonic boundary between Paraíba do Sul and Embu Terrains is the main reactivation zone in the Bocaina Ridge. AFT ages of ca. 55 Ma register the initial stage of the SBCR, which produced base level lowering and the formation of an inland scarp. The Bocaina Ridge seems to constitute an elevated region since the development of the Ribeira Cordillera, increased by the South Atlantic rift and post-rift uplifts and also by the SBCR.

Orogenic belts are fundamental features of plate tectonics. The crustal structure of orogens around the world shows a wide range of deformation styles from narrow, asymmetric wedges like the Pyrenees to wide, plateau-like orogens such as the Zagros or the Himalaya. The primary controlling factor on the size and structure of an orogen is the amount of convergence between the colliding plates. However, there are important additional factors providing major controls on the structural development of orogens. Among the potential parameters that can affect the style of deformation are the crustal strength, inherited weaknesses, and the surface processes. These parameters have been studied extensively in the past but their relative importance remains unclear. The aim of this thesis is to improve our understanding of: (1) How surface processes affect mountain building, with a special focus on the relationship between thin-skinned foreland and thick-skinned internal deformation of orogens. (2) How inherited extensional structures affect mountain building. The study was carried out using the Pyrenees as a special reference case. To answer our research questions we have used a wide range of state-of-the-art numerical modelling tools. In paper 1 we present a new method where we couple a structural-kinematic model and a thermo-kinematic model to evaluate the consistency of existing balanced section reconstructions with independent thermochronology data. In papers 2 and 3 we use 2D lithospheric scale thermo-mechanical models with surface process algorithms. Using the above toolset, we demonstrate that syntectonic sedimentation results in longer basement thrust sheets as well as longer thin-skinned thrust sheets and a generally wider orogen. Conversely erosion tends to narrow the wedge and reduce the orogenic loading of the colliding plates, limiting the space available for deposition in the flexural foreland deeps. We also demonstrate that inherited extensional structures play a crucial role in mountain building as they facilitate the migration of deformation into the undeformed basement of the overriding plate. Moreover, a significant amount of lower-crustal/mantle-lithospheric material is preserved at shallow depths only in the presence of extensional inheritance, but significant erosion is needed in order to bring this material to the surface. Our models also show that thin-skinned thrust sheets are generally rooted in the footwall of basement thrusts as they form outward-propagating sequences. As soon as a new basement thrust forms, the thin-skinned sequence situated on top of the new basement thrust-sheet is abandoned in favour of starting a new sequence in the footwall of the new thrust. Regarding our case study, it was possible to reproduce the section restoration using a structural-kinematic model with high accuracy up to the 36-Ma time slice and with limited accuracy up to the 50-Ma time slice. The thermochronometric ages predicted by the thermo-kinematic modelling are generally in good agreement with both the high- and low-temperature thermochronology data available in the Central Pyrenees; hence we conclude that the restoration is to a first order consistent with these datasets. The predicted thermochronological ages approximate the available low-temperature thermochronology data better by taking into account the late-stage burial and re-excavation scenario affecting the southern flank of the Pyrenean wedge presented by Coney et al. (1996), and quantified by Fillon and van der Beek (2012). In conclusion, our model experiments suggest, that extensional inheritance played a prime role in the structural evolution of the Pyrenees, with the major characteristics of the North Pyrenean Unit, including the presence of steep, inverted normal faults, the relative tectonic quiescence of the area after the early inversion and the presence of a lower-crustal body at shallow depth below the unit, best recaptured by our accordion models. / Orogenic belts are fundamental features of plate tectonics. The crustal structure of orogens around the world shows a wide range of deformation styles from narrow, asymmetric wedges like the Pyrenees to wide, plateau-like orogens such as the Zagros or the Himalaya. The primary controlling factor on the size and structure of an orogen is the amount of convergence between the colliding plates. However, there are important additional factors providing major controls on the structural development of orogens. Among the potential parameters that can affect the style of deformation are the crustal strength, inherited weaknesses, and the surface processes. These parameters have been studied extensively in the past but their relative importance remains unclear. The aim of this thesis is to improve our understanding of: (1) How surface processes affect mountain building, with a special focus on the relationship between thin-skinned foreland and thick-skinned internal deformation of orogens. (2) How inherited extensional structures affect mountain building. The study was carried out using the Pyrenees as a special reference case. To answer our research questions we have used a wide range of state-of-the-art numerical modelling tools. In paper 1 we present a new method where we couple a structural-kinematic model and a thermo-kinematic model to evaluate the consistency of existing balanced section reconstructions with independent thermochronology data. In papers 2 and 3 we use 2D lithospheric scale thermo-mechanical models with surface process algorithms. Using the above toolset, we demonstrate that syntectonic sedimentation results in longer basement thrust sheets as well as longer thin-skinned thrust sheets and a generally wider orogen. Conversely erosion tends to narrow the wedge and reduce the orogenic loading of the colliding plates, limiting the space available for deposition in the flexural foreland deeps. We also demonstrate that inherited extensional structures play a crucial role in mountain building as they facilitate the migration of deformation into the undeformed basement of the overriding plate. Moreover, a significant amount of lower-crustal/mantle-lithospheric material is preserved at shallow depths only in the presence of extensional inheritance, but significant erosion is needed in order to bring this material to the surface. Our models also show that thin-skinned thrust sheets are generally rooted in the footwall of basement thrusts as they form outward-propagating sequences. As soon as a new basement thrust forms, the thin-skinned sequence situated on top of the new basement thrust-sheet is abandoned in favour of starting a new sequence in the footwall of the new thrust. Regarding our case study, it was possible to reproduce the section restoration using a structural-kinematic model with high accuracy up to the 36-Ma time slice and with limited accuracy up to the 50-Ma time slice. The thermochronometric ages predicted by the thermo-kinematic modelling are generally in good agreement with both the high- and low-temperature thermochronology data available in the Central Pyrenees; hence we conclude that the restoration is to a first order consistent with these datasets. The predicted thermochronological ages approximate the available low-temperature thermochronology data better by taking into account the late-stage burial and re-excavation scenario affecting the southern flank of the Pyrenean wedge presented by Coney et al. (1996), and quantified by Fillon and van der Beek (2012). In conclusion, our model experiments suggest, that extensional inheritance played a prime role in the structural evolution of the Pyrenees, with the major characteristics of the North Pyrenean Unit, including the presence of steep, inverted normal faults, the relative tectonic quiescence of the area after the early inversion and the presence of a lower-crustal body at shallow depth below the unit, best recaptured by our accordion models.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / O relevo da Serra da Bocaina revela o forte controle das estruturas dúcteis e rúpteis relacionadas à Faixa Ribeira gerada na Orogênese Brasiliana (ca. 790-480 Ma) e às reativações mesozóica-cenozóicas. As rochas são agrupadas em 4 terrenos tectônicos colados nas etapas colisionais brasilianas, que formaram as estruturas mais penetrativas: foliação com mergulho para NW, zonas de cisalhamento dúcteis NESW e dobras. Zonas de cisalhamento rúptil-dúcteis NW marcam o colapso orogênico. A abertura do Atlântico Sul (ca. 135-120 Ma) é registrada pelos enxames de diques toleíticos NNE e ENE, em parte condicionados pelas estruturas brasilianas. No Planalto da Bocaina uma idade de traço de fissão em apatita (TFA) de ca. 145 Ma data o resfriamento ainda da fase pré-rifte do Gondwana. O soerguimento da margem continental na fase rifte pode ter alçado este nível para fora da zona de apagamento parcial do TFA. A reativação neocretácea é datada pelo TFA (ca. 85 Ma) na costa e na escarpa atlântica, indicando novo pulso de denudação e soerguimento da margem continental. Isto também concorda com o extenso aporte de sedimentação siliciclástica na Bacia de Santos. No Paleógeno, a formação dos Riftes Continentais do Sudeste Brasileiro (RCSB) gerou a reativação das estruturas dúcteis NE da Faixa Ribeira, falhas e fraturas NW, E-W, além de fraturas NE na Baía da Ilha Grande. O contato tectônico entre os Terrenos Paraíba do Sul e Embu é a principal zona reativada na Serra da Bocaina. Idades TFA (ca. 55 Ma) registram o estágio inicial do RCSB, que provocou o rebaixamento do nível de base e a formação de uma escarpa no interior. A Serra da Bocaina parece constituir uma região elevada desde a formação da Cordilheira Ribeira, incrementada pelos soerguimentos das fases rifte e pós-rifte do Atlântico e do RCSB. Estes eventos tectônicos que elevaram a Serra da Bocaina, também geraram as estruturas que conduzem sua denudação. Neste contexto, destaca-se o par de estruturas NE (foliação e zonas de cisalhamento reativadas ou não) e NW (fraturas e falhas), as mais freqüentes, que orienta a rede de drenagem, os níveis de base locais (knickpoints) e as formas côncavas das encostas (cabeceiras de canais). Diques toleíticos também conduzem a dissecação dos vales fluviais. Por outro lado, granitos e ortognaisses que sustentam as elevações e segmentos de escarpas mostram o papel da erosão diferencial em rochas mais resistentes. A denudação do Planalto da Bocaina e o recuo de suas escarpas (atlântica e interior) são regulados por diferentes níveis de base (p.ex. nível do mar, rio Paraíba do Sul no RCSB, diversos knickpoints), sensíveis aos eventos de reativações tectônicas (soerguimento), variações eustáticas e à erosão diferencial. Os pulsos erosivos vêm dissecando de modo diferencial os vales suspensos do planalto, através da incisão fluvial e reativação das cabeceiras de canais, que avançam sobre as encostas promovendo a quebra dos divisores e capturas de drenagens. Este processo rebaixamento de relevo parece levar à formação das superfícies colinosas que ocorrem em diferentes níveis topográficos. As idades TFA antigas indicam baixas taxas de denudação na porção mais elevada do Planalto da Bocaina, o que contrasta com as altas taxas da região costeira. Este caráter diferencial da denudação condicionada pelo substrato geológico e pelos eventos de soerguimento, vem preservando antigas paisagens no Planalto da Bocaina. No outro extremo, a denudação propagada pelo recuo das duas escarpas vem degradando as bordas e introduzindo a dissecação no interior do planalto. As duas escarpas geradas por eventos riftes distintos vêm se ajustando ao controle das rochas e estruturas da Faixa Ribeira. / The Bocaina Ridge landscape is strongly controlled by both ductile and brittle structures related to the Ribeira Belt (Brasiliano Orogeny ca. 790-480Ma) and also to the mesozoic-cenozoic reactivations. The rocks were subdivided in four tectonic terrains accreted in the brasiliano collisional stages. The most prominent structures related to these collisions are: NW dipping foliation, NE-SW ductile shear zones, and folds. NW ductile-brittle shear zones represent the orogenic collapse stage. The South Atlantic opening (ca.135-120 Ma) is registered in NNE and ENE tholeitic dike swarms, partly conditioned by brasiliano structures. In the Bocaina Plateau one apatite fission track age (AFT) of ca.145Ma represents pre-rift Gondwana cooling. The continental margin uplift associated to the rift phase might have raised this level out of the AFT partial annealing zone. Neocretaceous reactivation (ca. 85Ma) was AFT dated both in the coast and the atlantic scarp, pointing out to a newer continental margin denudation and uplift pulse. This reactivation is in accordance with the Santos basin significant siliciclastic sedimentation. In paleogene times, the Southeastern Brazil Continental Rift System (SBCR) development was responsible for: the reactivation of the Ribeira Belt NE ductile structures, NW and E-W faulting and fracturing, and NE fracturing in Ilha Grande Bay. The tectonic boundary between Paraíba do Sul and Embu Terrains is the main reactivation zone in the Bocaina Ridge. AFT ages of ca. 55 Ma register the initial stage of the SBCR, which produced base level lowering and the formation of an inland scarp. The Bocaina Ridge seems to constitute an elevated region since the development of the Ribeira Cordillera, increased by the South Atlantic rift and post-rift uplifts and also by the SBCR.

Controls on denudation in the eastern Bolivian Andes are evaluated by synthesis of new and existing denudation estimates from basin-morphometry, stream - powered fluvial incision, landslide mapping, sediment flux, erosion surfaces, thermochronology, foreland basin sediment volumes, and structural restorations. Centered at 17.5 °S, the northeastern Bolivian Andes exhibit high relief, a wet climate, and a narrow fold- thrust belt. In contrast, the southeastern Bolivian Andes have low relief, a semi-arid climate, and a wide fold-thrust belt. Basin -morphometry indicates a northward increase in relief and relative denudation. Stream-power along river profiles shows greater average incision rates in the north by a factor of 2 to 4. In the south, profile knickpoints with high incision rates are controlled by fold-thrust belt structures such as the surface expressions of basement megathrusts, faults, folds, and lithologic boundaries. Landslide and sediment-flux data are controlled by climate, elevation, basin morphology, and size and show a similar trend; short -term denudation-rate averages are greater in the north (1- 9 mm/yr) than the south (0.3-0.4 mm/yr). Long-term denudation-rate estimates including fission track, basin fill, erosion surfaces, and structural restorations also exhibit greater values in the north (0.2-0.8 mm/yr) compared to the south (0.04-0.3 mm/yr). Controls on long-term denudation rates include relief, orographic and global atmospheric circulation patterns of precipitation, climate change, glaciation, and fold-thrust belt geometry and kinematics. The denudation synthesis supports two conclusions: 1) denudation rates have increased towards the present 2) an along-strike disparity in denudation (greater in the north) has existed since at least the Miocene and has increased towards the present. Denudation rates and controls suggest that Bolivian mountain morphology is controlled by both its orientation at mid-latitude, and the feedbacks between uplift, kinematics, orographic effects on precipitation, glaciation, and the increased erosion that accompanies orogenesis.