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Present-day tectonic activity at the southern end of the Upper Rhine Graben in central Western Europe is evidenced by significant seismicity, which has been documented over hundreds of years. The hazard that is posed by this activity was violently demonstrated in 1356, when an earthquake with an estimated magnitude of ML≈6.5 caused extensive damage to the area of Basel in north-western Switzerland. A sound understanding of the regional tectonic deformation field is a prerequisite for the accurate assessment of this hazard. However, long-term deformation rates in this region are very low. Together with the presence of a network of fault families of different age and orientation, which results from the complex tectonic evolution of this area in the Neogene, this makes the characterisation of the regional deformation field and the identification of active faults difficult. Nevertheless, for a better comprehension of the active tectonic processes in general, and for the assessment of the seismic hazard in this region in particular, an improved understanding of the regional tectonic evolution in the recent geological past is indispensable. This thesis addresses the recent tectonic history of the Basel area by combining seismological data with an investigation of the geomorphological evidence of tectonic activity. The fact that tectonic activity can be recorded and preserved by the landscape provides an additional source of information that has been little used so far. It offers an opportunity to extend the time-scale of observation from the decades covered by (instrumental) seismologic and geodetic records further into the past. Whereas a wide range of geomorphic features can carry signatures of past tectonic events, the focus in this work is laid on fluvial geomorphology. The fluvial system in the northern Alpine foreland has been affected by a number of large-scale tectonic events since the late Oligocene. Apart from processes related to the Alpine orogeny and the rifting of the Upper Rhine Graben and Bresse Graben, the evolution of the Jura fold-and-thrust belt, the most external element of the Alpine orogen, dramatically influenced the drainage system. Sedimentary and morphological evidence of former river courses allow further constraining the evolution of the drainage system between the Oligocene and the Quaternary. The tectonic history in the Quaternary was studied using a quantitative geomorphological approach. On the basis of a digital elevation model, geomorphic indices (steepness and concavity index) were determined to characterise the longitudinal profile for a large number of rivers in the area of the southern Upper Rhine Graben and the eastern Jura fold-and-thrust belt. The spatial distribution of these indices indicates uplift of a region roughly corresponding to the Jura fold-and-thrust belt, as well as subsidence of the interior parts of the Upper Rhine Graben relative to the Tabular Jura. A morphological analysis of Late Quaternary alluvial terraces in the lower Aare valley, northern Switzerland, was carried out using a high-resolution digital elevation model. The results suggest regional northward tilt during the past 20’000 years, compatible with both a general (isostatic) uplift of the Swiss Molasse basin, and continuing convergence due to ongoing Alpine collision. The geomorphic data revealed no unambiguous evidence of recent tectonic activity on individual faults. Furthermore, no evidence of recent or ongoing thin-skinned deformation in the Mesozoic sedimentary cover could be identified. The study area at the junction of the Upper Rhine Graben and the Jura fold-and-thrust belt is characterised by a pronouncedly diffuse distribution of deformation, typical for regions where strain is accommodated on inherited tectonic structures. The superposition of large-scale regional uplift and small-scale deformation on individual faults, as well as seismic and aseismic movements, results in a distinct heterogeneity of deformation styles in the northern Alpine foreland.

This thesis was carried out within the framework of the international EUCOR-URGENT project and represents a joint study (co-tutelle) between the Universities of Basel and Besançon. It is devoted to the structural evolution and present-day tectonic activity of the region of Franche Comté in Eastern France, a region that is located at the intersection between the Jura fold-and-thrust belt representing the front of the Alpine orogen and the immediately adjacent northwestern foreland, characterized by the intra-continental Rhine-Bresse Transfer Zone (RBTZ). The formation of the RBTZ, that forms a central segment of the Paleogene European Cenozoic Rift System, involved the extensional reactivation of the Late Paleozoic Burgundy Trough System. Substantial extension occurred in Eo-Oligocene times and was achieved by ENE-WSW striking normal faults that are highly oblique to the dominant strike of the Rhine and Bresse grabens. Fission track data suggest that basement reactivation also contributed to the Eo-Oligocene exhumation of the Late Paleozoic La Serre Horst in the context of rifting. Basement reactivation in connection with the formation of the RBTZ resulted in complex fault patterns and local stress field perturbations, especially in the surroundings of the pre-existing Paleozoic horst structure. During Late Miocene to Early Pliocene times the northwestern most segment of the thin-skinned Jura fold-and-thrust belt, the Besançon Zone, encroached onto the RBTZ. Moreover, NW-SE directed foreland compression caused thick-skinned, transpressive reactivation of the RBTZ that started by Late Pliocene times at the earliest. Present-day seismicity in the RBTZ indicates that thick-skinned tectonics are still active and may reflect ongoing tectonic underplating in the northwestern Alpine foreland. Post-Pliocene relative rock uplift is recorded along the RBTZ by differential erosion of the Middle Pliocene Sundgau-Forêt de Chaux Gravels on a regional scale. Uplifted remnants of this gravel plain, identified by heavy mineral analyses, permitted to determine a latest Pliocene to recent minimum regional rock uplift rate of 0.05 +/- 0.02 mm/yr. A reconstruction of the Plio-Pleistocene drainage basin evolution of the Ognon and Doubs Rivers revealed that this relative rock uplift is still ongoing and most likely partly driven by the inversion of the RBTZ. Pleistocene folding near Besançon is evident from differentially up warped paleo-meanders along the Citadelle Anticline. This deformation is apparently enhanced by the bedrock incision of the Doubs River and associated with higher local uplift rates of 0.17 +/- 0.03 mm/yr. The results of this study vividly illustrate the dynamic processes that control the progressive evolution of continental collisional forelands. It appears that while the evolution of the RBTZ was largely controlled by the reactivation of pre-existing structures, its present tectonic activity is to some extent also controlled by surface processes and involves positive feedbacks between large-scale uplift, enhanced erosion and active deformation.

Combining thermochronological methods with structural field data, this study aims to reconstruct the Tertiary burial and exhumation history of the northeastern part of the Tisza‐ Dacia block during its invasion in the Carpathian embayment and final soft collision with the European margin. Zircon fission track data additionally provide information about the last metamorphic overprint during the Cretaceous. Within the basement units of the northern Central East Carpathians (Bucovinian nappe stack) and the Preluca massif (Biharia unit) zircon fission tracks are largely reset during the last (Cretaceous) orogeny. Temperatures during this Alpine metamorphic overprint increase from external to internal within the northern East Carpathians from sub‐greenschist facies conditions to at least greenschist facies conditions. Greenschist facies conditions are also observed in the Preluca massif. The close neighbourhood of Coniacian to Campanian zircon FT cooling ages with Cenomanian sediments suggests Late Cretaceous tectonic exhumation in the northern East Carpathians. The most likely explanation for this tectonic exhumation is a ‐ so far undocumented ‐ Late Cretaceous extension related to orogenic collapse (Gosau type basins). The Tertiary evolution is characterised by the invasion of the previously amalgamated Tisza‐Dacia and ALCAPA blocks into the Carpathian embayment and Miocene soft collision of both these blocks with the European margin. The juxtaposition of the ALCAPA and Tisza‐Dacia blocks, with Tisza‐Dacia in a lower plate position, is announced by the onset of Oligocene turbiditic sedimentation. The Burdigalian SE‐directed over‐thrusting of the Pienides (non‐ metamorphic flysch units) is interpreted to express the final stages of this juxtaposition. Burial heating caused full annealing of fission tracks in apatite (i.e. >120°C) in the Central East Carpathian basement in the NE of the study area, while in the basement of the Preluca massif in the SW of the study area temperatures related to Paleogene to Early Miocene burial did not exceed 80°C. The post‐Burdigalian (post‐16 Ma) soft collision of Tisza‐Dacia with the European margin occurred in two stages expressed by predominantly sinistral strike‐slip deformation during constant NE‐SW shortening. During and following soft collision, combined uplift and erosion caused exhumation of the buried rocks along the European margin. Uplift reaches up to 9 km in the Rodna horst The first post‐Burdigalian transpressional stage (16‐12 Ma) is related to perpendicular convergence of Tisza‐Dacia with the NW‐SE striking European margin. Minor exhumation during this stage resulted in Middle Miocene apatite fission track cooling ages (15‐13 Ma) in the west of the study area. The transtensional stage (12–10 Ma) led to the formation of the Bogdan‐Dragos‐Voda fault system. Sinistral transtension allowed for the docking and fitting of Tisza‐Dacia with the NW‐ SE striking European margin. Oblique E‐W convergence led to strain partitioning with thrusting in the external thrust belt and internal strike‐slip deformation. Differential lateral movements are distributed and deformation is accommodated by E‐W striking sinistral strike slip faults and SW‐NE striking normal faults, which led to fragmentation into SW‐tilted blocks. Fragmentation and differential offset along the bounding faults resulted in the formation of triangular‐shaped graben and corresponding horst structures. Enhanced exhumation during transtensional activity led to advective heat transport and resulted in Middle to Late Miocene apatite fission track cooling ages (13‐7) in the east of the study area.

Chapter 1: Apparent divergence of thrusting directions horth and south of the Pelvoux massif: implications for the evolution of the Western Alpine Arc: In the Western Alps, the Penninic Basal Contact (PBC, Ceriani et al. 2001) defines the tectonic boundary between the external Dauphinois domain and the interanl Penninic units. During the Eocene, the PBC corresponds to the suture between Dauphinois and Subriançonnais/Briançonnais domains related to the subduction of the Valais ocean (Ceriani et al. 2001). In the Oligo-Miocene, i.e. during a second and post-collisional stage, Eocene structures were passively transported towards the WNE along a major out-of-sequence thrust, the Roselend thrust (RT), partially coinciding with and reactivating the PBC. Structural analysis of key outcrops combined with microfabric investigations of calcyte ultramylonites allowed to trace the southern continuation of the RT in a broad shear zone at the rim of the Pelvoux massif and further south along the Briançonnais front (Tricart 1980) at the rear of the Embrunais Ubaye nappe stack. The RT finally branches into a sinistral strike slip zone NE of the Argentera massif. The area south of the Pelvoux massif is additionally characterized by SW-directed thrusting, a feature totally absent north of it. Detailed investigations of outcrops found along strike of the RT, the basal decollement of both Dauphinois para-autochthonous Tertiary cover and Helmenthoid Flysch of the Embrunais Ubaye nappe stack reveal that top-SW thrusting is a younger (i.e. D2) event, overprinting earlier features linked to D1 WNW-directed displacements. The youngest deformation event found in the area (D3) is consistent with normal faulting along the Durance system. On a larger scale, it is concluded that the whole Adriatic indenter was thrusted onto the European plate along the RT during Oligo-Miocene times. Activity along this structure is linked to dextral movements along the Rhone-Simplon line and sinistral movements at the rear of the Argentera massif. Additionally, it is proposed that the onset of D3 SW-directed movements finds its origin in the opening of the western Mediterranean basin and the foramtion of the Appenine chain in middle Miocene times. Chapter 2: Microfabrics of calcite ultramylonites recording coaxial and non-coaxial deformation kinematics: examples from the Rocher de l'Yret shear zone (Western Alps): Microfabrics were analysed in calcite mylonites from the rim of the Pelvoux massif (Western Alps, France). WNW-directed emplacement of the internal Penninic units onto the Dauphinois domain has lead to intense deformation of an Eocene-age nummulitic limestone under lower anchizone metamorphic conditions (slightly below 300°C). Two types of microfabrics developed during deformation under coaxial or non-coaxial kinematics, respectively, primarily by dislocation creep accompanied by dynamic recrystallization in the absence of twinning. Coaxial kinematics are inferred for samples exhibiting grain shape fabrics and textures with orthorhombic symmetry. Their texture is characterized by two c-axis maxima at the periphery of the pole figure, symmetrically oriented at 15° from the normal to the macroscopic foliation. Non-coaxial deformation is evident in samples with monoclinic shape fabrics and textures characterized by a single oblique c-axis maximum tilted with the sense of shear by about 15°. From the analysis of suitably oriented slip systems for the main texture components under given kinematics it is inferred that the orthorhombic textures developed in coaxial kinematics fabour activity of and slip along the f- and r-planes, respectively, with minor contributions of basal slip. In contrast, the monoclinic textures developed during simple shear are most suited for duplex slip along the basal plane. The transition between orthorhombic and monoclinic microfabrics is interpreted to be due to the effects of dynamic recrystallization upon texture development. Calcite textures alone should not be used as unequivocal shear sense indicators, but need to be complemented by microstructural criteria such as shape preferred orientations, grain size estimates and amount of twinning. Chatper 3: Microfabric analysis of calcitic marbles from the area investigated in the Western Alps and the Gavernie basal contact (Central Pyrenees): In the previous chapter, a model of microfabric evolution of calcite ultramylonites, plastically deformed at temperatures lower than 350°C, has been presented. The very specific setting of the outcrop investigated in great details at the "Rocher de l'Yret" shear zone (RYSZ) allowed for the recognition of both coaxial and non-coaxial deformation kinematics. The samples deformed with a dominant component of rotational deformation show a c-axis distribution tilted synthetically with the sense of shear. In the absence of twinning, this feature, commonly observed for quartz tectonites, can be used as a reliable shear sense indicator. Additionally, the model allows for the recognition of incipient rotational deformation in the bulk flow accommodated in the rock. The structural data presented in chapter 1 will now be completed by means of a microfabric analysis of a series of calcitic marbles, found in abundance in the investigated area. The results of investigations on calcite ultramylonites found along the Roselend Thrust (RT) are presented first. four localities along the RT have been investigated between the eastern rim of the Pelvoux massif in the North and the rear of the Argntera massif in the South (sites BFY, Laux, Reot and Arg in fig 3.1). This study aims to 1) independently confirm the overall WNW-directed sense of transport along the RT, 2) deduce the type of strain along this structure and its possible variations using the model of microfabric evolution presented in chapter 2. In a second step, the basal decollement of the Dauphinois parautochthonous cover from the southeastern rim of the Pelvoux massif will be investigated. Such decollement occurred within the nummulitic limestone layer intensively mylonitised in the Dormillouse valley (site Dorm, see fig. 3.1 and 3.2). This study confirms the overall top-SW overprinting deformation recorded in this domain and documents important bulk flow partionning within the basal decollement level of the Eocene stratigrahpic series. Finally the restults of investigations on samples from the Gavernie thrust from the central Pyrenees (courtesy J.H.P. de Bresser) will be presented (see fig. 3.37). The restults are in accordance with the overall top-S directed emplacement of the Gavernie nappe during Pyrenean orogeny and give evidence for strain variations within the shear zone developed along the Gavarnie basal thrust., pas de résumé

In the Rio Tinguiririca valley in the Main Cordillera of the Andes of central Chile, 35 ° south, parts of a stratigraphic section ranging from the late Jurassic to the Quaternary are exposed. Fission track analysis was carried out on samples from all the stratigraphic units exposed in the area in order to gain information on the low–grade metamorphic history of the Central Andes and to test older models for the metamorphic and tectonic evolution of the area. The sequence exposed in the Rio Tinguiririca valley is characterised by several distinctive features not found in other localities in the Central Andes; the deposits of the middle Cretaceous (Aptian – Albian) Colimapu Formation and of the middle to late Micoene Farellones Formation are completely missing in the study area. Instead, a volcanic tuff layer, the White Tuff, and a unit consisting of fan deposits and alluvial plane deposits, the Brownish–Red Clastic Unit, unconformably overlie the Late Jurassic deposits of the Ba˜nos del Flaco Formation. The fission track data give some indications on the style and timing of metamorphic events in the study area, enable more accurate constraint of the age of the Brownish–Red Clastic Unit and allow some statements on the tectonic evolution of the study area from the Late Jurassic to present. Burial metamorphism has been proposed by various authors as the main mechanism to produce large suites of rocks altered at low grades in the Central Andes. The results of this study indicate that, on the contrary, hydrothermal alteration connected to magmatic and/or volcanic activity was the main cause of alteration of the rocks and that burial metamorphism played at most a very minor role. Pulses of hydrothermal activity appear to have occurred from Cretaceous to almost recent times and led to alteration of the rocks at slightly varying metamorphic conditions at different times in different parts of the study area. A new model is proposed for the tectonic evolution of the study area. Fission track analysis of detrital zircons from the Brownish–Red Clastic Unit shows that the unit must have been deposited during the latest Cretaceous (Maastrichtian) and that it is certainly younger than the White Tuff. Thermal modelling shows that considerable exhumation of the lower part of the Rio Damas Formation occurred during the Late Cretaceous to Early Tertiary. This exhumation is thought to be connected to tilting and erosion of the Mesozoic units in the area prior to the formation of an extensional basin in the Late Eocene. Data from the Eocene to Miocene Coya Machali Formation imply that sedimentation within the Tertiary basin continued somewhat longer than hitherto supposed.