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The Llert syncline is located in the South-central Pyrenees, between the eastern termination of the EW-trending Cotiella Basin and the north-western limb of the NS-trending Turbón-Serrado fold system. The Cotiella Basin is an inverted upper Coniacian-lower Santonian salt-floored post-rift extensional basin developed along the northern Iberian rift system. The Turbón-Serrado fold system consists of upper Santonian - Maastrichtian contractional salt-cored anticlines developed along an inverted transfer zone of the Pyrenean rift system. Based on field research, this paper presents a 3D reconstruction of the Llert syncline in order to further constrain the transition between these oblique salt-related structures. Our results suggest that the evolution of the Llert syncline was mainly controlled by tectonic shortening related to the tectonic inversion of the Cotiella Basin synchronously to the growth of the Turbón-Serrado detachment anticline, and by the pre-compressional structural framework of the Pyrenean rift system. Our contribution provides new insight into the geometric and kinematic relationships of structures developed during the inversion of passive margins involving salt.

The western Pyrenean Mauléon basin allows to discuss the tectono-sedimentary and thermal evolution of a hyperextended rift through an entire Wilson cycle. During Permian time, the western Pyrenees record the shift between N-S convergence recorded in the Pyrenean Axial Zone (310 to 290 Ma) and dominant E-W extension (290 to 275 Ma). This latter stage is responsible for a complex thermal, structural and compositional inheritance of the Pyrenean lithosphere. The preservation of the original Permian-Triassic paleogeography and structure in the “Basque Massif” indicates that there was no major east-west Mesozoic strike-slip motion between the Iberian and European plates in this part of the Pyrenees, questioning the mechanisms responsible for the opening of the Early Cretaceous North-Pyrenean rift system. The Cretaceous Mauléon hyperextended rift basin was inverted during the Alpine orogeny. Reactivation of the former rift structures leads to the formation of a lithospheric scale pop-up whose edges are characterized by differing tectonic reactivation style, localized (Iberia) vs distributed (Europe). The previously exhumed mantle acts as a buttress inhibiting the complete closure of the basin. In 3D, the N120° thrusts systems edging the pop-up are composed of different thrust segments branching into the inherited Permian N20° transfer zones, highlighting the non-cylindrical geometry of the Pyrenean structures. Permian and Cretaceous structural inheritance both control the synrift and post-collisional thermal evolution of the Mauléon basin. Synrift paleogeothermal gradients gradually increased from the margins (~ 34°C/km) to the basin (~ 60°C/km). Maximum peak temperatures are both controlled by sedimentary burial and mantle heat flow (100 mW.m-2). The different post-collisional thermal responses of the Mauléon basin pop-up edges is linked to their tectonic reactivation style. On the European margin, the postrift isotherms were passively transported onto the proximal margin (« thin-skinned »). On the Iberian margin, peak temperatures were acquired after thrusting (« thick-skinned »). The review of the hyperextended Iberian-Eurasian plate boundary basins shows that they strongly differ from classical Atlantic-type passive margins. Three main stages of continental crust thinning can be inferred to describe the evolution of this smooth-slope type extensional basin : (1) a dominant ductile thinning of the lower crust, without significant brittle deformation of the upper crust, resulting in the formation of a symmetric sag basin; (2) basinward gliding of the prerift cover along the Late Triassic evaporites; (3) hyper-extension with brittle deformation on the proximal margins and dominant ductile thinning on the hyperextended rift domain (HT/LP metamorphism)., Localisé dans les Pyrénées occidentales, l’étude du bassin de Mauléon, permet d’appréhender l’évolution tectono-sédimentaire et thermique d’un rift hyper-aminci de son héritage pré-extensif à son inversion (cycle complet de Wilson). L’épisode permien reflète le passage de la convergence N-S enregistrée dans la Zone Axiale (310 à 290 Ma) à une phase d’extension E-W (290 et 275 Ma), conférant un héritage thermique, structural et rhéologique complexe à la lithosphère des Pyrénées occidentales. La préservation des traits paléogéographiques permo-triasiques rend impossible la réalisation d’un mouvement décrochant sénestre E-W au Mésozoïque entre l’Ibérie et l’Europe, dans cette partie des Pyrénées, questionnant les modalités d’ouverture des bassins nord-pyrénéens au Crétacé. Au cours de l’orogenèse alpine, le bassin hyper-étiré de Mauléon est inversé. La réactivation des structures crétacées conduit à la formation d’un pop-up lithosphérique dont les bordures présentent des styles de réactivation différents, localisé (Ibérie) vs distribué (Europe). La protubérance mantélique héritée de la phase de rifting crétacée empêche l’inversion complète du rift en jouant le rôle de buttoir. En 3D, les systèmes de chevauchement sont composés de plusieurs segments délimités par les zones de transferts N20° héritées du Permien conférant un caractère non-cylindrique au structures orogéniques pyrénéennes. L’héritage permien et crétacé contrôle à la fois l’évolution thermique synrift et post-collisionnelle du bassin de Mauléon. Les paléo-gradients géothermiques synrifts augmentent de manière graduelle des marges (~ 34°C/km) vers le bassin (~ 60°C/km). La température maximale est alors contrôlée par l’enfouissement et le flux thermique mantélique (100 mW.m-2). La différence de réponse thermique observées sur les bordures du bassin de Mauléon est liée au style de déformation compressive : diminution du gradient dans le domaine hyper-étiré et la marge européenne ~ 25.0 ± 2.7°C/km vs augmentation du gradient sur la marge ibérique < 30°C/km). L’étude tectono-sédimentaire des bassins mésozoïques adjacents d’Arzacq et de Tartas, couplée à un travail de synthèse sur les bassins péri-ibériques souligne les nombreuses différences existant entre ces bassins et ceux des marges hyper-étirées atlantiques. L’évolution de ces « bassins extensifs à pente douce » comprend trois grands stades de déformation : (1) un amincissement ductile de la croûte inférieure, sans déformation cassante significative dans la croûte supérieure, formant un rift symétrique (sag) ; (2) un glissement de la couverture prerift sur les évaporites du Trias; (3) une phase d’hyper-extension avec déformation fragile des marges proximales et amincissement ductile du domaine distal hyper-étiré (métamorphisme HT/BP).

In this thesis, the 3D structure and kinematics of the locally and mildly inverted Lower Austria Mesozoic Basin beneath the Alpine-Carpathian fold-and-thrust belt is described. This study has been carried out by the integrative interpretation of 2D and 3D seismic surveys, well and geophysical logs data and gravity maps. A basin-scale, 3D structural model has been carried out, focused on the sub-thrust and foreland zones. The Late Eocene to Early Miocene Alpine–Carpathian fold-and-thrust belt resulted from the subduction of the European plate beneath the Adriatic one, and the subsequent continental collision between both plates. The Alpine–Carpathian foredeep and fold-and-thrust belt recorded the long-lasting involvement of the European crystalline basement in several deformation events: from late Variscan transtension, to Jurassic rifting, and Cretaceous to Neogene shortening. In this thesis, two additional basement fault reactivation events have been defined in relation to the Alpine-Carpathian Cenozoic shortening: an extensional reactivation event related to the bending of the European plate coeval with Egerian to Karpatian (ca. 28–16 Ma) thin-skinned thrusting; followed by the selective positive inversion of the basement faults in the sub-thrust and in the foreland during Karpatian to Badenian times (ca. 16-12.5 Ma). The flexural bending of the European plate and the associated extensional fault reactivation were promoted by high lateral gradients of lithospheric strength in addition to the slab pull forces associated with subduction. Delamination of the European lithosphere during the final stages of collision around Karpatian times (ca. 16 Ma) promoted a large-wavelength uplift and an excessive topographic load. This topographic load was compensated by broadening the orogenic wedge through the compressional reactivation of the inherited fault array in the Euroepan plate beneath and ahead of the thin-skinned thrust system. Ultimately, collapse and deep burial of the Alpine-Carpathian tectonic wedge took place by the formation of the Pannonian basins system. To gain further insights in the deformational processes in sub-thrust and foreland settings, sandbox analogue models of brittle and brittle-viscous sand wedges have been carried out. The models aimed testing the influence of different topographic loads (i.e., thrust wedges) on the sub-thrust inversion of extensional basins, as well as the influence of the initial orientation of the extensional basins, and the presence or absence of weak detachment layers. Segmented half-graben basins -striking at 90º, 45º and 15º to the extension direction- were created first, and then shortened using different angles for the basal detachment and topographic slope. A shallow layer of viscous polymer over the half- graben basin was included in one of the models. The experiments were analysed using time-lapse photography, topography laser scans and image-based 3D voxels. The modelling results indicate a deformation sequence characterised by layer-parallel compaction, fault reactivation, thrust propagation and related folding. Fault reactivation and basin inversion were associated with layer-parallel compaction accomplished by slip along the basal detachment, prior to and in between pulses of thrusting. The results of the sandbox analogue models reveal a fundamental control imposed by the vertical load of the tectonic wedge and its integrated strength profile in the inversion of sub-thrust basins. Small vertical loads or strong gradients of vertical load have revealed as fundamental factors aiding in the inversion of buried, sub-thrust basins. The integrated strength profile resulted from the combination of inherited, strain-softened fault zones, as well as the presence or absence and distribution of weak, viscous horizons. The results of the sandbox models carried out indicate that the vertical load, its gradient over the sub-thrust basins and the inherited, strain-softened faults, are more important than the obliquity between the direction of shortening and the orientation of pre-existing fault systems. As indicated by the results of sandbox analogue models, the recurrent and long-lasting frictional reactivation of the Lower Austria basement fault array may have been favoured by fault-weakening mechanisms, as well as by steep gradients of vertical loads generated by thin-skinned out- of-sequence stacking of the Rhenodanubian Flysch located south of the inverted basement fault array.

[cat]Aquesta tesi presenta l’evolució cinemàtica dels Pirineus centre-meridionals durant el Terciari a partir de la integració de dades magnetostratigràfiques, termocronològiques I magnetotectòniques del seu registre sinorogènic. La datació magnetostratigràfica dels conglomerats sintectònics de La Pobla de Segur, Senterada i Sis, fixa la seva edat en Eocè mig-Oligocè superior (cron 19r a cron 9n). Aquests resultats permeten establir una nova cronostratigrafia pels materials eocens-oligocens dels Pirineus centre-meridionals de la que deriven implicacions biocronològiques, ja que canvia substancialment les edats acceptades del nivells de referència europeus MP14 a MP17. Les edats magnetostratigràfiques s’han combinat amb termocronologia detrítica de blocs de granit dels conglomerats sintectònics. La termocronologia obtinguda varia de 63 a 27 Ma. Els models tèrmics revelen tres períodes de refredament ràpid relacionats amb el moviment de grans encavalcaments a la Zona Axial, destacant l’ocorregut a l’Eocè superior-Oligocè inferior degut al moviment de l’encavalcament de Rialp i a l’increment de relleu a la Zona Axial per underthrusting. L’annealing post-deposicional de les mostres estratigràficament més baixes suggereix que el cinturó de plecs i encavalcaments pirinenc va estar cobert per 2 km de materials. Els models tèrmics també suggereixen una exhumació ràpida al Miocè superior, relacionada amb la captura de l’Ebre al Mediterrani. Durant la sedimentació dels materials sinorogènics estudiats té lloc la formació de thrust salients als Pirineus meridionals entre els que destaca la Zona Obliqua d’Ainsa. L’estudi magnetotectònic dut a terme en aquesta zona revela rotacions verticals que varien de ~80º a Mediano a ~20º al nord d’Añisclo. L’edat de la rotació principal a la làmina de Gavarnie s’estableix en el Lutecià-Bartonià, quan eren actives totes les estructures de la Zona Obliqua d’Ainsa, i estaria causada per una diferència de 50 km en la quantitat de desplaçament de la làmina de Gavarnie controlada per la distribució de les sals triàsiques al seu desenganxament basal. La sincronia entre encavacalments i rotacions apunta a un model d’arc progressiu amb transport divergent. Aquests resultats revelen una estreta relació entre el registre estratigràfic dels materials sinorogènics, els encavalcaments i l’exhumació a la Zona Axial i l’evolució estructural del sistema d’envacalments dels Pirineus meridionals. Les forces tectòniques van controlar els patrons d’exhumació, l’evolució de la topografia sinorogènica de les conques intramuntanyoses i d’avantpaís i les característiques deposicionals dels sediments sinorogènics., [eng]This PhD Thesis presents the Tertiary kinematic evolution of the South-Central Pyrenees from the integration of magnetostratigraphic, magnetotectonic and thermochronological analyses on its synorogenic sedimentary record. One of the main contributions of this PhD thesis is the continuous absolute dating of the syntectonic conglomerates of La Pobla de Segur, Senterada and Sis. Magnetostratigraphy of these materials establishes their deposition during Middle Eocene-Late Oligocene times (from chron 19r up to chron 9n). Integration of these results with previous magnetostratigraphic works within the Ainsa Basin has allowed the establishment of a new chronostratigraphy for the Eocene-Oligocene materials of the South-Central Pyrenees. The obtained chronostratigraphy has biochronological implications as it substantially changes the traditionally accepted ages of the European reference levels MP14 to MP17. MP14 and MP15 reference levels are proposed to correlate to Lutetian whereas MP16 and MP17 would be Bartonian in age. These results reveal that the correlation between the continental and marine Paleogene record needs further refinement and therefore, that the chronostratigraphic age attributions based on MP reference levels should be taken with caution. The magnetostratigraphic ages have been combined with detrital thermochronology on 13 granitic cobbles enclosed in the syntectonic conglomerates. The detrital apatite fission track ages obtained vary from 63 to 27 Ma. When these ages are combined with the stratigraphic ages, samples define 5 groups with thermochronological ages generally increasing down-section except in the most deeply buried ones due to post-depositional partial annealing. Thermal models reveal three periods of rapid-cooling within the Axial Zone due to movement on large-thrust sheets. A dramatic increase in exhumation rate occurred during the latest Eocene-Early Oligocene related to the onset of movement in the Rialp thrust sheet and the increase in structural relief of the Axial Zone by underthrusting. The magnetostratigraphic and thermochronological ages obtained permit the link between the sedimentation rates in the surrounding basins and the exhumation rates in the hinterland, and reveal that accommodation space exerted the main control on sedimentation rates within the piggy-back basins. Post-depositional annealing of the stratigraphically lowest samples suggests about 2 km of burial by the younger synorogenic materials during progressive burial of the South Pyrenean fold and thrust belt. Thermal models also suggest a rapid exhumation event during the Late Neogene, linked to re-excavation caused by the base level drop during the Ebro River capture to the Mediterranean Sea. Sedimentation of the studied synorogenic materials during Middle Eocene-Oligocene times occurred coeval to the development of thrust salients in the southern Pyrenees. The magnetotectonic study of 36 sites carried out in the Ainsa Oblique Zone reveal clockwise vertical-axis rotations varying from ~80° in the lower Lutetian materials of the Mediano anticline to ~20° in middle Ilerdian materials cropping out at the northern edge of the Añisclo anticline. Sites in the central part of the Montsec and Bóixols thrust sheets don’t record any significant rotation as neither do the syntectonic materials of La Pobla, Sis and Senterada. The age of the main rotation event within the Gavarnie thrust sheet is constrained to Lutetitan to Bartonian times, when all the structures of the Ainsa Oblique Zone were active. This vertical-axis rotation stage obeys to a difference of ~50 km in the amount of displacement on the Gavarnie thrust sheet controlled by the NE-SW pinch out of the Triassic salts at its basal detachment. A second rotation event of ~ 10° took place since Priabonian times, as a result of the differential displacement of about 22 km of the Serres Marginals thrust sheet, respect the Gavarnie one, on top of the upper Eocene-Oligocene evaporites. The synchronicity between thrusting and vertical-axis rotations suggests that the curved fold and thrust belt formed by progressive curvature with divergent thrust transport. The results exposed in this Thesis reveal a strong relationship between the stratigraphic record of the synorogenic materials, thrusting and exhumation in the Axial Zone and the structural evolution of the South Pyrenean thrust system. Tectonic forces controlled the observed patterns of exhumation, the evolution of the synorogenic topography of the piggy-back and foreland basins and the depositional features of the synorogenic sediments.

La finalitat de l’estudi és la d’intentar esbrinar alguna característica més d’aquesta interacció mecànica entre capes veïnes. Així, seran simulats diversos models de capes en els quals aquesta interacció mecànica entre capes veïnes és possible. L’estudi inspecciona condicions per a la formació de fractures, o famílies de fractures, en models de més d’una capa, tenint en compte diferents variacions en les propietats mecàniques i les potències de les capes estudiades. El document consisteix bàsicament de dues parts diferenciades: • Una revisió literària, a on es resumeix una col·lecció de publicacions sobre estudis referents a fracturació i les conclusions a les que han arribat. • Simulacions i modelització, a on s’inspecciona un aspecte de la fracturació: l’efecte de les fractures, en termes de tensió i deformació, en les capes veïnes. No s’estudia el procés de fractura en sí, sinó que s’investiga l’efecte de una o dues capes sobre les seves capes veïnes, aplicant sobre elles desplaçaments i deformacions en les capes inicialment fracturades, i veient la seva influència en les capes veïnes.