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A new model of plate kinematics in the Scotia Sea region is presented in which continental crustal blocks and the signatures of seafloor spreading are defined semi-automatically using gravity and total field magnetic anomalies and some of their residuals, transformations and derivatives. This study is the first of the region to integrate gridded magnetic and gravity data in order to make reconstructions, and one of the first anywhere to make full use of gridded magnetic data in an inverse procedure. The context provided by the quantitative reconstructions allows qualitative assessment of visually-derived reconstructions of small movements in the region. The Scotia Sea floor consists of three large oceanic magnetic provinces: the west,central and east Scotia seas, and four smaller sub-basins, all enclosed within the elevated submarine and emergent Scotia Arc. The Scotia Arc consists of Mesozoic continental and Cenozoic island-arc fragments. Only the east Scotia Sea remains active; the west and central parts are the products of extinct spreading centres. West Scotia sea spreading is reasonably well described by tectonic flowlines expressed in satellite free-air gravity anomalies and magnetic reversal isochrons in total field anomalies. These data are combined in an inversion to reconstruct the west Scotia Sea's margins between its inception at thron C8 (- 26.5 Ma) and extinction at chron C3a (- 6 Ma). The results suggest strongly, and for the first time, that the west Scotia Sea formed as a small ocean basin whose passive margins were Tierra del Fuego and the central Scotia Sea, and not as a back-arc basin in the strict sense. During its growth the kinematics of the west Scotia Sea's margins approximated those of the South American and Antarctic plates. The small kinematic differences are suggested to be due to convergence at the `proto-South Sandwich-Discovery' subduction zone, to the east of the central Scotia Sea, and to dextral strike-slip (pre-C6 (N 20 Ma)) and oblique convergence (post-C6) at the North Scotia Ridge, the Mesozoic northern arm of the Scotia Arc. The most widely-accepted interpretations of the central Scotia Sea hold that it is a back-arc basin, but model flowlines about published reconstruction poles in the region show that instead it could have originated by accretion to the South American plate at the ancestral South American-Antarctic Ridge in the Weddell Sea, later to move eastwards as the eastern passive margin to the west Scotia Sea. Magnetic reversal anomalies in the central Scotia Sea are consistent with its accretion in this way during the Cretaceous, probably between chrons M4 and M20 (- 126-149 Ma). All of this material was hitherto thought to have been destroyed completely by subduction at the ancestors of the South Sandwich subduction zone. The central Scotia Sea is thus also re-assigned in the model to have an oceanic, rather than back-arc basin, origin. Hence, the bulk of the Scotia Sea floor formed as a consequence of the predictable movements of major plates following the break-up of Gondwana, with back-arc basins in the strict sense only forming small subbasins until the inception of the east Scotia Sea at or soon after C5c. The development of this much larger, oceanic, back-arc basin occurred following a change in the direction of relative motion at the West Scotia and South American-Antarctic Ridges at C6. This new model of Scotia Sea kinematics, presented as a series of reconstructions of total field and Bouguer anomalies, is the first to be both self-consistent and consistent within the context of known major plate motions. The new interpretation of the central Scotia Sea is at odds with previous reconstructions which place South Georgia in the heart of a reconstructed compact connection between Tierra del Fuego and the Antarctic Peninsula. The altered position of South Georgia, south of Maurice Ewing Bank (Falkland Plateau) helps explain the puzzling provenance of its turbidites and suggests, as previous workers have done, that it may be appropriate to redefine the genesis of at least the eastern part of the Rocas Verdes Basin as an oceanic basin formed by accretion at a propagating rift, rather than (as before) a rare example of a back-arc basin formed behind an east-directed subduction zone. Although the new model is self-consistent, it is not uniquely so for two of the small basins in the Scotia Sea (Protector and Dove Basins) whose age remains poorly defined.It can be speculated that either or both of these basins may have opened deep-water gateways in the Drake Passage region prior to spreading in the west Scotia Sea, possibly in the Middle Eocene. A very tentative correlation between such events and initial cooling prior to the onset of Antarctic glaciation, via the cooling effect of establishing an efficient Antarctic Circumpolar Current, is suggested.

This study focuses on the impact of potential changes in the wind-wave climate on shoreline change. The 'one-line' model for medium to long-term prediction of coastline evolution is employed. New analytical and numerical solutions of this important model are described. Specifically: 1) original semi-analytical solutions are derived that relax the unrealistic assumption of existing analytical work that a constant wave condition drives shoreline change and, 2) a more general form of the one-line model is solved with a novel application of the 'Method of Lines'. Model input consists of 30-year nearshore wave climate scenarios, corresponding to the 'present' (1961-1990) and the future (2071-2100). Winds from a high resolution, (12km x 12km), regional climate model, obtained offshore of the south-central coast of England at a dense temporal resolution of 3 hours, are used to develop the aforementioned wave climate scenarios, through hindcast and inshore wave transformation. A hypothetical shoreline segment is adopted as a 'benchmark' case for comparisons. Monthly and seasonal statistics of output shoreline positions are generated and assessedfo r relative changeso f 'significance' between 'present' and future. Different degrees of evidence that such changes do exist are found. This study is the first application of such high resolution climate model output to investigate climate change impact on shoreline response. Major findings include: 1) shoreline changes of 'significance' are strongly linked to 'significant' changes in future wave direction, 2) future changes appear smaller for entire seasons than for individual months, 3) shoreline position variability is often smaller in the future, 4) different climate model experiments produce diverging results; however, general trends are largely similar. The present study, at a fundamental level, offers analytical solutions of the 'oneline' model that are closer to reality and a numerical solution that is of increased effciency. At a practical level, it contributes to better understanding of the patterns of shoreline response to changing offshore wave climate through: 1) the use of fast and straightforward methods that can accommodate numerous climate scenarios without need for data reduction, and 2) the development of a methodology for using climate model output for coastal climate change impact assessment studies.

Enigmatic craters tens of kilometres in diameter have been mapped previously at the top of Oligo-Miocene ooze on the mid Norway margin. In this study seismic reflection data are used to map slides, craters and mounds in the M[unknown] Basin to better understand how the craters form. Many craters are filled by a slide named Slide W, which is by volume similar to the Storegga Slide, but which was translated only a few kilometres. Mounds mapped in the vicinity of craters filled by Slide W on the top surface of Slide W consist of sediment remobilised from the ooze in which the craters are incised. Mounds generally pinch out onto the top surface of Slide W and are emplaced on a palaeo-seabed, suggesting that failure of Slide W, incision of craters filled by Slide W and remobilisation of ooze occurred contemporaneously. A model is presented linking these processes to gas hydrate dissociation. Rapid deposition of less permeable sediment burying more permeable ooze leads to shoaling of the base of a gas hydrate stability zone towards the top of the ooze and the base of the rapidly deposited sediments. Dissociation of gas hydrate increases the pore pressure of the ooze. If pore pressure becomes equal to lithostatic pressure, fracturing of the overburden and venting of methane may occur, leading to slope failure. Alternatively, build up of pore pressure primes or triggers the slide. Ooze is liquefied and emplaced on the seabed through vents or faults developing in the slide, forming a crater in the subsurface into which the slide subsides. A new class of structure is defined (Subsurface Gas Expulsion Structures), and the significance of these structures is discussed.

Extensional fault arrays at all scales and from different settings, commonly consist of fault sets with different strikes, either due to basement influence, or because of local stress perturbations. These non-colinear fault arrays are characterised by different types of high- angled fault intersections. Significant research has been undertaken into the process and product of colinear fault propagation and linkage in three dimensions, but there is little understanding of the kinematics of multidirectional fault array evolution. Detailed interpretation of the 3D geometry and displacement distributions of intersecting faults has been carried out in four case-study areas in order to further the understanding of kinematic interaction of non-colinear faults. These studies are: a polygonal fault system from the Voring Basin cross-cutting faults from the Gulf of Mexico extensional faults at the tip of a strike-slip fault in the Levant Basin and intersections between grabens trends in Canyonlands National Park, Utah. Intersections display a range of geometries that have been classified into five groups. An intersection may vary between classes within the vertical section. It is not possible to determine the evolutionary style of an intersection by geometry alone but detailed analysis of displacement distributions can reveal the growth histories of the intersecting faults. Faults that meet at high-angled intersections are interpreted to interact kinematically, and show two distinct evolutionary styles: accidental and branching intersections. Accidental intersections form where the intersecting fault propagates toward the main fault plane and relationships that fit this style are defined as abutment, soft and hard linkage and cross- cutting. Evolutionary sequences from abutment to hard linkage, soft to hard linkage and abutment to cross-cutting are identified. Branching intersections form where the intersecting fault propagates away from the main fault plane. A new method for network evolution, termed lateral bifurcation, is proposed for this style of intersection.

This thesis uses a combination of industrially acquired seismic reflection data, well data, topographic data and satellite imagery to investigate the structure, evolution and geophysical expression of extrusive constructions found within large (-500 m diameter) mud volcano systems from the South Caspian Basin. The principal aim is to gain a better understanding the structural architecture of mud volcano systems and the ways in which they are constructed. To this end this thesis includes three core research chapters which present investigations into the internal structure and eruptive history of a large mud volcano system, the geophysical response of seismic data to gassy seabed conditions and the structure and formation of mud volcanic subsidence craters. In the first core chapter the edifice of the giant C'hirag mud volcano system was investigated using three-dimensional (3D) seismic data. Internally, this feature consists of a number of discrete seismic facies units interpreted to represent either wedge-shaped units of erupted mud volcanic sediment or sheet-like units of non-eruptive sediment. Unit stacking patterns indicate the importance of pulsed mud volcanic activity as a control on the internal architecture of large mud volcano edifices and suggest it to be an important mechanism of basinal sediment and fluid expulsion. Analysis of the geometrical relationships of the internal sediment units to an underlying collapse caldera allows for a reconstruction of the system's history of collapse. Together, the details of internal unit type, stacking and relative edifice collapse timing constitute a detailed reconstruction of the volcano system's eruptive history and a record of the structural evolution of a large focussed fluid flow system. At the seabed a number of volcano systems within the South Caspian Sea study area were found to be imaged by areas of phase-reversed seabed reflection in seismic data. These "seabed phase reversals" are useful for better delimiting and understanding the structure of mud volcano source points and the extent of recent eruptive deposits. At one example kilometre-scale lobate mudflows are seen emerging from two seabed mud pool (salses) emphasizing the importance of both features in shaping the volcano's seabed morphology. Testing the hypothesis that seabed phase reversals are the result of gas within the seabed sediment took the form of a one-dimensional geophysical model of the study area seabed constructed using data from a borehole together with other published data. The results revealed that a phase reversal of the seabed reflection is a geophysical possibility under conditions typical of gassy seabed sediment. There is therefore a high likelihood that seabed phase reversals are the result of gas within seabed sediment. It is therefore suggested that seabed phase reversals can be used alongside other acoustic phenomena that indicate the presence of gas in a sedimentary section. In the final core chapter circular craters found at the upper terminations of onshore and offshore mud volcano systems are investigated. Using field maps. seismic lines, topographic data and satellite images it has been possible to describe these craters in detail for the first time and compile a generalized model for their structure. This includes a crater rim, an inward dipping crater margin fault, a moat and raised crater pedestal of freshly extruded mud volcanic sediment. The characteristic "moat and pedestal" morphology features at most of the craters featured here as well as at a number of others from elsewhere. Whilst the precise mechanism of crater formation is unclear it is strongly suspected that they form as a result of subsurface evacuation and collapse. They are thus similar to other sedimentary and igneous collapse features for which they may be useful analogues.

This thesis uses industry 3D seismic to investigate the nature and distribution of strain in a deep water fold and thrust belt and describes the complex fault plane and stratal geometries that result from fold and thrust linkage. The principal aim is to gain a better understanding of the structural architecture and evolution of toe-of-slope compressional settings. To this end, the project represents a logical series of arguments involving the study of individual structures and fold and fault pairs, to considering a fold belt as a whole. The outer thrust belt of the Niger Delta is observed to comprise of synthetic and antithetic faults that interact and link along strike. A preliminary geometric classification is proposed for antithetic thrust fault linkage zones based on observations of fault surface and stratal geometries. The relationship between fault interaction and fold characteristics is also investigated. The connectivity of stratigraphic horizons across fault surfaces and through transfer zones is shown to vary with the type of linkage and with depth. Conclusions drawn on the along strike variability of fault network density, orientation and vertical extent are shown to have significant application to modelling of fluid flow. The concept of numerous and geometrically distinct thrust fault linkages forming through-going folds is developed through the investigation of a single isolated fold that comprises a number of linking forethrusts and backthrusts. This case study, involving the quantification of the development of this relatively simple structure, allows conclusions to be drawn on fold growth that are later applied to a more complex and closely spaced fold belt. The internal structural geometry of faults and stratigraphic horizons within the single fold are described though detailed three-dimensional mapping. The analysis of the distribution of fault and fold strain, both on individual thrusts within the fold and for the structure as a whole, suggest efficient displacement transfer between numerous linking faults that accommodated shortening as a coherent unit. In addition to this, variations in the magnitude of fault heave are compensated by complementary trends in fold strain. A study of syn-kinematic units demonstrates that the single structural culmination present today was initially made up of a number of folds with local structural highs. Major thrust surfaces within the fold are also interpreted to be the product of the along strike linkage and amalgamation of initially distinct faults. These observations made on the isolated fold are applied to a complex, closely spaced fold belt. The relative timing of individual faults and folds agree with established models of a progressive foreland propagating sequence of thrust faults but also display out-of-sequence events. Findings demonstrate a significant period of synchronous development between all structures in the fold belt. Aggregation of fault and fold shortening profiles indicate that displacement transfer occurs along strike and also in a dip-parallel direction between within the fold belt. Bulk shortening is thus conserved along strike within the syn-kinematic units and low lateral heave gradients suggest efficient displacement transfer between all constituent structures. The evidence presented here shows that all elements of a fold belt can be kinematically linked during growth. Irregularities in the distribution of deformation in pre-kinematic units corroborate findings that the folds are the product of along strike linkage of discrete segments, in a similar manner to that documented in extensional systems.

A detailed investigation of the structural evolution of the deepwater west Niger Delta was undertaken from the combination of industry 2D and 3D seismic reflection datasets. The study has been focused on three themes: crustal architecture, thrusting in oceanic crust and the role of multiple detachments in developing the structural style in the area. Detailed analysis and mapping of the basement structures, crustal thickness and distribution, identification and analysis of thrust-fault pattern and its relationships to detachment levels have provided a completely new understanding of the structural evolution of the deepwater west Niger Delta. The study shows that the area is underlain by oceanic crust that is characterised by a thickness of 5-7 km and by internal reflectivity consisting of both dipping and sub-horizontal reflectors. Inclined reflections can be traced up to the top of the crust where they offset it across a series of minor to major SW-NE striking basement thrusts in the SE of the study. The crust is thinnest around a major transform structure, the Chain Fracture Zone possibly related to the local geometry of the spreading fabrics with no significant variation the crustal thickness across the transform zone. Detachments are located within the 'Dahomey unit', and the transition between the Agbada and Akata Formations (Top Akata). Quantitative measurements of fault displacements show that the utilisation of different detachments results in contrasting styles of thrust propagation and fold growth. Two geographical zones are defined. In zone A, (NW sector of the study area), the stratigraphically shallowest Dahomey detachment is dominant and is associated with thrust truncated folds while in zone B, (SE sector of the study area) a stratigraphically lower detachment approximately at the Agbada-Akata Formation boundary is associated with thrust propagation folds.

Low-angle normal faults have been extensively documented in areas of regional extension, in both continental and oceanic lithosphere, but their existence as seismically active structures remains controversial. Low-angle normal faults do not conform to 'traditional’ frictional fault theory, and large earthquakes on low-angle normal faults appear to be rare. Their enigmatic nature suggests that they may hold important clues regarding the rheology of fault zones in general, controls on frictional behaviour, and the deformation histories of the mid- to upper-crust. In this study, I investigate the internal structure, mechanical properties, and fluid flow conditions along a large-displacement low-angle normal fault exposed on the Island of Elba, Italy. Using field relationships, microstructural analysis, stable isotope geochemistry, and rock deformation experiments, I document the most important characteristics of the fault zone, and test hypotheses concerning the mechanical behaviour and evolution of low-angle normal faults. The Zuccale low-angle normal fault crosscuts and displaces a lithologically heterogeneous sequence of wall rocks. Field relationships suggest that it was active in the upper crust during the emplacement of large plutonic complexes. On a regional-scale, the Zuccale fault appears to have a long-wavelength domal morphology, which may have resulted from the intrusion of an upper-crust igneous pluton in to the shallow footwall of the fault. Pluton intrusion strongly influenced the fluid flow regimes and fault rock evolution along the Zuccale fault. Geometric and kinematic relationships between the Zuccale fault and a network of minor footwall faults suggest that the Zuccale fault slipped at a low-angle throughout most of its history. The footwall faults were active broadly contemporaneously with movement along the Zuccale fault, and controlled the distribution and connectivity of different fault rock components. This imparted a distinct mechanical structure to the fault core, potentially influencing fault zone rheology. The central core of the Zuccale fault contains a sequence of fault rocks that deformed by a variety of deformation mechanisms, and formed during progressive exhumation of the fault zone. Triaxial deformation experiments indicate that the frictional strength of many of the fault rocks is too high to explain slip along the Zuccale fault. However, several potential mechanisms of fault zone weakening have been identified, including fluid-assisted dissolution-precipitation creep, grain-size sensitive creep in calcite mylonites, frictional sliding within phyllosilicate-rich areas of the fault core, high fluid pressures, and particulate flow accommodated by fine-grained clay minerals. Fluids associated with the Zuccale fault were derived from two main sources. During the relatively early stages of movement, and particularly during the intrusion of plutonic complexes, fluids were of meteoric-hydrothermal origin. During the late stages of exhumation, fluids were derived from a seawater source that infiltrated downwards through faulted and fractured wall rocks. Sub-horizontal tensile veins carrying both fluid signatures are found adjacent to and within the fault core, suggesting that supra-lithostatic fluid pressures were able to develop throughout the exhumation history. One of the consequences of high fluid pressures was the development of a suite of fluidized fault breccias, a newly recognized type of fault rock that may be indicative of the interseismic stage of the earthquake cycle.