The southern Albania thrust belt comprises Mesozoic - Eocene carbonate sequences incorporated into three major Tertiary thrust sheets verging towards the Apulia foreland in the southwest. The problem of the structural evolution has been previously approached through a hypothesis of orthogonal thin-skinned thrusting controlled by a differential areal extent ofPermo-Triassic evaporites. This thesis uses the interpretation of several seismic profiles to address questions such as those relating to the subsurface geometric patterns ofthe thrust sheets, the kinematic framework the evaporites operated in, the role ofthe pre-existing faults and the timing ofthe evolution. The interpretation demonstrates that significant along - strike changes characterize the subsurface geometry of the thrust sheets. The Permo-Triassic evaporites facilitated their buttressing against a buffer zope in the Apulian foreland primarily within an orthogonal compression regime. Regional clockwise rotation about a pivot point to the north may have provided a transpressional component along the thrusts. Pre-existing normal faults played a significant role on thrusting and accomodation of the strain partitioning. The main structural events included thin-skinned thrusting during Oligocene - Aquitaniane, formation of a buffer zone in the forelarni during Burdigalian and subsequent thrust - buttressing during the Miocene. Post - Pliocene deformation occurs in the foredeep basin.

In 1951, it was first suggested by E.M. Anderson that faults in nature will form at specific angles to the maximum principal stress. For most cases, this concept agrees with observations. However, in nature there are some notable exceptions to this rule, with some faults becoming activated in unfavourable orientations. This project was designed to examine conditions that might affect the angle of faulting and the friction coefficient for sliding. Faults that do not conform to generally accepted ‘Andersonian’ theory include low-angle detachment faults (e.g. Basin and Range Province (USA)), the San Andreas Fault (USA) the Nordfjord Sojn Detachment (Norway), high angle (steeply dipping) normal faults (Britain) and the Zuccale Fault, Italy. Various explanations have been given for sliding on these unfavourably-oriented faults, including high pressure CO2 or water infiltration (Zuccale Fault), low-friction minerals growing in fault gouge (Zuccale fault, San Andreas Fault), stress refraction (San Andreas Fault), reactivation of thrust faults (Nordfjord Sojn Detachment) and fracture under a combination of compression and tension (UK).Experiments were performed in compression and extension using a triaxial deformation rig. Darley Dale sandstone and Pennant sandstone blocks were cut into cores and tested under the following conditions: (a) intact rock failure (dry); (b) sawcut at 35°, 45° and 55° (dry) to the core axis using (i) constant confining pressure, (ii) constant normal stress (iii) constant mean stress; (c) with pore pressure in all three sawcut angles; and (d) with a gouge layer of 70% quartz to 30% kaolinite mixed with 0, 2, 5, 10, 20, 50 and 100% wt of either graphite or talc. Microstructural studies were carried out on deformed samples. These experiments showed that: The angle of failure in extension was 16-20° to the maximum principal stress for Darley Dale sandstone, and 18-21° for Pennant sandstone whereas in compression it was >30°. This angle in extension is lower than expected, but microstructural analysis indicated occurrence of stress refraction, which may help explain this result. The friction coefficient does not appear to change with pre-cut fault angle in dry samples. Pore pressure tests confirmed the general applicability of the law of effective stress, but anomalous apparent reduction of friction coefficient and production of an apparent cohesive strength in pore pressure tests suggested tests should be run slower to avoid disparity between applied pore pressure and true pore pressure in the sample. Attempts to induce hydraulic fractures showed that high overpressures may often be required to do this. Addition of a low-friction phase (talc or graphite) to fault gouge reduced friction by a disproportionately large amount for very planar faults. This was shown to be due to mechanical smearing of the weak phase over the fault plane, increasing its apparent area of coverage. It was concluded that commonly some combination of high fluid pressure in fault planes coupled with low-friction fault gouges may be required to explain slip on natural, unfavourably –oriented faults.

Extensional fault propagation and linkage play an important role in the structural and sedimentological development of rift basins. In this study, use of 85,000km² 3D seismic data provides a new and unique opportunity to evaluate and quantify the processes of fault growth within an evolving rift system. The study uses a comprehensive dataset from the East Shetland Basin and North Viking Graben, northern North Sea to document the evidence for, and effects of fault growth during the Mid to Late Jurassic (Bajocian to Ryazanian) rift episode. Integration of excellent biostratigraphic control with these seismic data enables enhanced temporal control than that which can be achieved in the field. The data allows the development of a new 4-dimensional holistic model in which strain localisation can be shown to be the dominant control on the spatial and temporal evolution of structure in an evolving rift province. The significance of my approach is the integration of seismic stratigraphic analysis combined with facies analysis and biostratigraphy in the East Shetland Basin to demonstrate that during the Mid to Late Jurassic rift episode the locus of extension migrated from west to east towards the Viking Graben. Systematic documentation of the variation in age of syn-rift deposits across the basin shows that motion on faults ended progressively throughout the Kimmeridgian and Portlandian with the latest motion occurring on the Visund-Gullfaks- Alwyn fault array during the Volgian. The effect of strain localisation towards the basin centre with time caused passive rotation of earlier (more westerly) structures (e.g. Snorre) and their hangingwall depocentres. This is the first study to challenge the traditional view that the Mid to Late Jurassic structures in the East Shetland Basin were active synchronously throughout the rift episode. Detailed interpretation of the syn-rift architecture associated with four major faults situated on a 100km long, east-west transect across the basin allows the development of a detailed model in which the timing of activity on a suite of faults can be accurately quantified. Initially, during the Upper Bajocian, extension was characterised by a large number of small faults of both dip directions which grew by radial tip propagation and subsequent segment linkage. Strain was initially focussed onto a small number of throughgoing fault arrays at the expense of less optimally positioned structures. The focussing of strain onto these structures resulted in an increased slip rate and upward bowing of the footwalls, leading to the development of release faults formed as a result of differential vertical displacements along the length of the fault. These small (less than 10km long) structures form perpendicular to the main fault and show maximum displacement of c. 300m at their proximal end decreasing away from the main fault. As the rift episode progressed, strain was gradually localised towards the rift axis. It culminated in the Ryazanian with localisation of strain onto the rift axis. At this time activity was primarily confined to a single thoroughgoing fault, the Visund-Gullfaks Fault, defining the western edge of the North Viking Graben. As such the Visund-Gullfaks Fault developed to be the largest fault in the basin both in terms of length (125km) and maximum accumulated displacement (>5km) as a result of the basinward (eastward) migration of the locus of extension.

The Kamasia Hills are formed essentially by a line of 'en echelon' tilted blocks within the main rift valley in northern Kenya. The metamorphic basement crops out locally at the foot of the eastern fault-scarps of the range and is overlain by the thickest sequence of the late Miocene plateau phonolites so far known. in Kenya. This sequence, which includes minor amounts of basic and intermediate lavas and thick sedimentary units, is described, together with that of a thick series of Pliocene basalts, trachytes and fossiliforous sediments exposed in the foot-hills to the east of the main range. Isotopic (K-Ar) age determinations from the lavas facilitate the dating if the main geological events. Deformation is by normal faulting, associated with block tilting and fault-bounded flexuring on axes normal to the dominant fault trend. Faulting episodes are identified by consideration of stratigraphic relationships and movement on the largest faults is shown to have occurred repeatedly. Major features of the geomorphology are described and a geomorphde tectonic history is constructed for the area. Volcanism was mainly of the plateau, lava1 type; very few volcanic centres were found in the area but it is apparent that the western limits of both volcanic activity and minor faulting have moved towards the rift centre with time. The petrography of the lavas is summarised and fifty-one representative chemical analyses are presented and discussed, A major faulting episode in the early Pliocene which, from field relations, clearly terminated the phase of phonolite lava extrusion is shown also to define a distinct petrochemical break-with respect to both the mafic and the felsic lavas. Problems of petrogenesis are briefly considered.

Deep seismic reflection profiling has revealed reflective upper crustal structures, often interpreted as faults or shear zones, and sometimes a strongly reflective lower crust. This thesis investigates what crustal reflections represent, and to what extent seismic sections can be used to investigate a three-dimensional Earth. The lower crust often consists of reflective bands and transparent zones. An analogy is drawn between the geometry of reflective bands seen in the lower crust and the orientation of shear zones likely to develop in a plastic lower crust during both bulk pure and simple shear. These results suggest that lower crust reflections come from shear zones. Crustal reflections are often cross-cutting and shorter than the Fresnel Zone diameter. Simple 2-D seismic modelling demonstrates that these reflection segments often do not directly represent real structure, but are rather the product of complex spatial interference, which is itself controlled by the geometrical packing of the reflecting surfaces. Intersections of orthogonal profiles and limited three-dimensional modelling are combined with these results to provide constraints on the three-dimensional shape of lower crustal reflectors. The results are consistent with shear pods and boudins within shear zones, supporting the hypothesis that lower crust reflections are from shear zones. These results are then integrated with other data to provide a model for lower crustal reflectivity and structure. The modelling results show that 3-D control is vital in interpreting crustal reflections, which must be viewed as an interference pattern, and so can only crudely define structure. These conclusions are emphasised in structural interpretations of crustal reflections observed on grids of seismic data, from the southern North Sea and the Oberpfalz region of West Germany.

The Sygnefjell area straddles the northwestern margin of the Jotun Nappe. It has a tectonically stacked sequence of four fundamental rock units, tentatively dated from regional correlations: 1. Basal Gneiss: Precambrian autochthonous granodioritic orthogneisses. 2. Parautochthonous cover: Cambro-Ordovician quartz schists, quartzitic psammites and limestones. 3. Supracrustal allochthon: Precambrian and possibly Cambrian arkosic psammites, metavolcanics, conglomerates and limestones. 4. Jotun Nappe: Precambrian strongly tectonized orthogneisses overlain by, and correlated with, meta-gabbros and monzonites preserving igneous textures. All units have undergone polyphase metamorphism in the greenschist and epidote-amphibolite facies during the Caledonian orogenic cycle. This imposes marginal tectonic and metamorphic concordance with the supracrustals upon the enveloping crystalline rocks which have undergone earlier tectonometamorphic events. Accompanying metamorphism are several phases of deformation, of which three produce the pervasive textures and tectonic superposition of the Sygnefjell sequence. These are: D₁ and D₂: Isoclinal folds producing a composite (and often mylonitic) penetrative schistosity and banding. The D₂ folds face northwest where strain is lowest, but rotate towards the D₂ finite extension direction (southeast at 25 degrees) with progressive shear. D3: Early structures are mostly small, asymmetric, northwest verging buckle folds developing, with continuing deformation, northwesterly directed thrusts in the forelimb. These early folds are cross-cut by later brittle thrusts which sometimes follow D₂ mylonite zones. Footwall cut-offs,imbricate geometry and direction of climb are all indicative of northwesterly displacement. Later deformation events (D₄ to D₆) are a response to tectonic thickening of the succession during D₃. From a knowledge of the deformation sequence, amount of ductile strain and direction and amount of tectonic movement a tentative restoration of Stratigraphic thicknesses and relationships can be made. This restoration and the structural data used in its construction imply a reinterpretation of the provenance of the Jotun Nappe and underlying supracrustal rocks.

The Batang Natal River flows across the Western Barisan Mountains of North Sumatra, exposing a section through the Woyla Group, a major unit of Sumatran island arc basement. Detailed field mapping of the section, followed up by thin section petrology, structural analysis and radiometric dating, was undertaken in order to investigate the geology, structure, origin and tectonic evolution of the Woyla Group. The Woyla Group outcropping in the section is divided into eighteen lithotectonic units, each with distinctive lithological characteristics, including basalts, volcanogenic turbidites and debris flows, and esites, spilites, chert-limest?ne breccias, non-marine volcanogenic sediments, quartz-mica schists, metaturbidites, megabreccias, serpentinite, diorite and massive limestones. Most units are deformed to varying degrees of intensity by tight to isoclinal 'F' folding with an associated 'S1 foliation. A later phase of open 'F2' folding deforms the 'S' foliation, as well as other layered units unaffected by 'D'. All the units are bounded and internally disrupted by strike-slip faults, commonly of NW/SE or WNW/ESE trend. Previous models interpreted the Woyla Group as the remnants of a closed marginal basin. The new model proposed here suggests the Woyla Group is a Mesozoic accretionary complex, built up of pelagic and terrigenous sediments, together with fragments of island arc and oceanic material, that were accreted against the Mesozoic Sumatran continental margin. The complex later subsided, to form part of the basement of the Tertiary forearc basin. The Sumatran Fault System, initiated in the late Mesozoic, or possibly earlier, as a consequence of oblique subduction; transected the Sumatran forearc and the magmatic arc. It resulted in major disruption, translation and reshuffling of fault slivers, thereby assembling the allochthonous and parautochthonous terranes now seen in the Woyla Group. The Woyla Group was subaerially exposed by the late Miocene-early Pliocene uplift of the Barisan Mountains.

The development of Polygonal Fault Systems (PFS) remains poorly understood despite extensive study for over two decades. These systems of exclusively normal faults are developed over wide areas of many basins worldwide and are believed to influence caprock integrity and hydrocarbon reservoir quality, whilst also potentially presenting shallow drilling hazards. A seemingly obvious conclusion from their layer-bound nature and significant lateral extent is that their origin must be governed by the constitutive behaviour of the host sediments. Establishing specific causative mechanisms has, however, proven difficult. The aim of this research project is to first assess some existing arguments for PFS genesis and this is complimented by a review of modification of structure in soft rocks and discussion of how this facilitates changes in both shear and compaction. The approach in this work is to utilise geomechanical forward modelling to demonstrate how such changes might lead to PFS formation. The concepts of this approach are discussed with focus on the adopted computational framework and selected constitutive model. An argument for polygonal fault genesis is presented that is founded on diagenetically induced shear failure, and the requirements for incorporating this into the constitutive model are described. Recovery of realistic PFS geometries is demonstrated as validation of the geomechanical argument and the competency of the computational approach. Conceptual sensitivity studies at the field scale are undertaken to better understand what processes, reactions and conditions might control fault genesis and propagation. When observed in mapview polygonal faults commonly intersect bedding planes at a wide variety of azimuths which reflects an inferred horizontally isotropic state of stress. Occasionally, this so-called 'planform geometry' is modified by the presence of tectonic faults, slopes or salt structures. Therefore, there is the possibility that polygonal faults may be useful paleostress indicators. This is explored using the characterised materials in simple models featuring anisotropic horizontal stress conditions.

Sediment flux from the Alps shows a sharp increase around the Mio-Pliocene boundary (~5 Ma). This observation, linked to the exhumation of the Swiss Molasse basin since ca. 5-4 Ma has led to the suggestion that the Alps experienced accelerated exhumation and isostatic uplift at the orogen scale since this time. The core objectives of this thesis are to assess whether we can document post 5 Ma exhumation of the Alps and its spatial and temporal development, and to review the different potential (tectonic or climatic) factors controlling this denudation. I have developed a novel technique that uses isoage contours associated with age-elevation relationships to exploit the unique density of fission-track ages in the western European Alps, reconstruct cooling isoage surfaces and estimate exhumation rates on the orogen scale between 13.5 and 2.5 Ma. The exhumation histories reconstructed for eight areas of the Western Alps display strong similarities in timing and rate with orogen-wide average denudation rates inferred from sediment volumes. Exhumation rates increased more than twofold since Late Miocene times, and may have been locally modulated by the distinct response of different tectonic units. I then searched for correlation between the spatial pattern of long-term exhumation rates, from the apatite fission-track record, and potential controlling parameters. In the Western Alps, long-term exhumation rates correlate strongly with presentday rates of rock uplift, implying that the rock uplift pattern observed today is ancient. I also observed that the spatial pattern of released seismic energy does not correlate with rock uplift or exhumation, which suggests that exhumation is controlled by isostatic rebound rather than by active tectonic uplift. The lack of correlation between exhumation rates and the presentday distribution of precipitation suggests that the present-day pattern is either non representative of the long-term trend or that factors other than precipitation rate dominate the intensity of exhumation. In order to study the exhumation history in more detail, I sampled two elevation profiles in the central Aar massif (Switzerland) and the western Lepontine Alps (Italy) for AFT and AHe dating which are characterised by steep age-elevation relationships around 8 and 4 Ma. I used the Pecube model to predict AFT and AHe ages according to several tens of exhumation scenarios and compared modeled and measured ages. The results of numerical modeling do not reject the hypothesis of two exhumation pulses at 9-7 and 5-3 Ma in the Aar massif. However, this signal is not detected in the Lepontine Alps, and contingent upon further flexural modeling, the exhumation recorded in the Aar massif since 5 Ma does not match the amount required to explain the denudation in the Swiss Molasse basin by flexural isostatic rebound. Rather, the data hint at an additional mechanism of rock uplift, such as the delamination of lithospheric mantle.

This research project used 3D seismic data located in deep water fold and thrust belt in the Levant Basin eastern Mediterranean, to investigate the nature and kinematics of compartmentalized thrust related folds. The principal aim is to better understand thrust related fold development and interactions in compressional settings. The fold and thrust belt in the Levant Bain is mainly comprised of overlapping thrust faults of similar and opposing dips segmented or bounded by conjugate sets of strike slip faults. Detailed interpretation and analysis of the 3D geometry of the structures revealed that thrust faulting is an early process in the development of the thrust and fold pair, thrust interact with each other, and strike slip faults along strike. A preliminary end member interaction of thrust faults and strike slip faults is proposed based on observation of their bounding or segmenting pattern. The concept of fault interaction was mainly developed from the investigation of the propagation of thrust fault compartmentalised by strike slip faults. This involves a combination of kinematic analysis which includes fault displacement and shortening profiles, and the patterns of syn kinematic sediments above fold limb. Kinematic data suggests that strike slip faults are acting as barriers to thrust fault propagation. Similar barrier to fault propagation are observed between overlapping thrust faults within a single fold formed by the linkage of smaller thrust folds. The results showed that the faults are restricted as they link and transfer displacement. In addition to the propagation of thrust faults, vertical distribution of fault displacement suggests that they ramp up from detachment, this agrees with the classical models of thrust propagation folds.