This research project uses high-quality seismic data from the Ottar Basin offshore Norway, Espírito Santo Basin offshore Brazil and Taranaki Basin offshore New Zealand. It investigates the geometry of multiple families of extensional faults and the effect(s) of fault growth on their seal competence. The main aims of this thesis are to investigate: a) the relationship between fault growth and deposition, b) the influence of fault reactivation in the compartmentalisation of strata around salt structures, and c) three distinct study areas as potential zones for enhanced fluid migration and seafloor seepage. Structural controls on three distinct petroleum systems were analysed based on the interpretation of the 3D geometry of seismic horizons, the mapping of fault displacements and throw distributions, and by modelling distinct faults taking into account present and past tectonic stresses. The geometry and kinematics of the Samson Dome, offshore Norway, were investigated to propose a new evolutionary model for this salt structure, and to assess the timing(s) of salt uplift, salt collapse, and reactivation of adjacent faults. Faults were investigated using detailed displacement analyses and 3D models. Fault modelling took into consideration present-day in situ stresses, and also relative paleostresses. The results demonstrate an evolution occurring in three distinct stages, which were thoroughly discussed in this thesis. The Samson Dome is a structure where structural compartmentalisation is more important at depth, with dip-linked reactivated faults being preferential paths for fluid migration at shallow depths. However, their seal competence is enhanced 1100 ms below the sea floor, below which fluids can be trapped. iv The geometry of fault families adjacent to distinct salt structures was assessed in the Espírito Santo Basin, offshore Brazil. Halokinesis is recorded from the Late Aptian to the Early Eocene, for four distinct salt structures, and controlled fault geometry and fluid flow patterns. The results in this thesis indicate a decrease in the seal competence of faults generated close to the studied salt diapirs. A conceptual model proposes that salt structures are linked by corridors of reactivated faults, which comprise preferential fluid-flow pathways from the South to the North-Northwest. The Parihaka 3D survey of the Taranaki Basin was used to investigate the geometry of submarine channel systems formed in association with the reactivation of fault segments during the opening of the Northern Graben, a structure with regional expression offshore New Zealand. Three main drainage types were described around the Parihaka Fault. The results in this thesis suggest that the larger displacements observed led to the formation of two depocentres to the NE of the study area, which were progressively filled by submarine-channel and prograding deltaic units. New results from this thesis include the assessment of the evolution of the Samson Dome, SW Barents Sea, and any controls of fault reactivation on the generation of structural compartments above this structure. This approach resulted in the recognition of the Samson Dome as a smaller seepage structure than previously considered in the literature. In the Espírito Santo Basin, faults reactivated by dip-linkage adjacently to salt diapirs and salt walls are the structures most favourable to record fluid leakage. In the Taranaki Basin, submarine channels may not use relay ramps between reactivated fault segments to reach hanging-wall depocentres. The results in this thesis can also be extrapolated to petroleum systems developed on continental margins worldwide.

The search for life on Mars continues apace, however the significant cost in time and resources involved in each robotic mission, whether orbiter, lander, or even rover, necessitates the use of terrestrial Martian analogue sites. Few regions on Earth are able to accurately simulate the conditions on Mars, yet locations such as the Atacama Desert of northern Chile and McMurdo Dry Valleys of Antarctica offer invaluable opportunities to test experiments and equipment prior to missions, as well as to advance understanding of the survival of life at the limits of habitability. This study presents an exciting new analogue region in the Chilean Altiplano, offering a unique balance of Mars-like conditions not experienced in other terrestrial Mars analogues. Utilising this novel Martian analogue, the present study examines how signs of ancient life may be preserved in the soils and sediments of Mars, investigating the extent of protection afforded by soil coverage against the inhospitable conditions of the surface. In addition, this study presents a new approach to understanding the bacterial community which does survive in such a hostile environment on Earth, illustrating the effect of soil coverage on the survival of bacteria in a Mars-like environment. The rapidly-changing nature of hostile soil conditions with increasing soil depth was found have stark implications for the likelihood of success of upcoming missions such as the ESA 2020 ExoMars Rover, as well as advancing the understanding of life in extreme – and under reported – environments on Earth.

The detailed palaeontological and lithological succession was established by detailed measurement and mapping of the Hurdlow, Pyeclough and Blake Brook sections. Faunas were found and are described ranging from E1c to E2b2 in age, and their extent within the North Staffordshire basin area and in Edale, Derbyshire, has been determined.

Any industrial site producing contaminants (including chemical and radiological materials), will be constructed on or below the surface, whose associated properties determine how fluid and contaminants travel. The Dounreay Nuclear Power Establishment offers a unique opportunity to understand bedrock geology, superficial deposits, shallow fractures, and their controls on fluid and contaminant pathways. This is due to its complex history, possible contaminants and extensive prior site investigations. Three-dimensional geological modelling is becoming an integral part of site investigations as affordable technology becomes more powerful. Using previously collected, data and state-of-the-art modelling, a high-resolution geological model has been created based on understanding the cyclicity of the Devonian sedimentation of the Orcadian Basin. This underlies the site providing a framework for discrete fracture network and stochastic facies modelling. A discrete fracture network, for three fracture sets, has been created for the bedrock geology through statistical analysis of scanline and borehole data, and stochastic simulations of fracture intensity throughout the geological model. Due to the heterogeneity of the superficial deposits, a stochastic simulation was used to interpolate five distinct superficial facies, considered to influence contaminant pathways and identified from geotechnical logs; 1–Clay, 2–Sand, 3–Gravel, 4–Silt and 5–Peat. Fracture intensity of the hydraulically conductive bedding-parallel fracture set decreases logarithmically with increasing depth. The decreasing fracture intensity of the bedding-parallel fractures reflects a decreasing horizontal hydraulic conductivity, which at 100m levels off and becomes approximately equal to the vertical hydraulic conductivity. The superficial deposits are predominantly clay, with the maximum hydraulic conductivity associated with the gravel facies. The gravel facies provide connectivity from the land surface to the bedrock and associated fracture networks. Methodologies used here can be applied to any site investigation, providing adequate data is available, and by integration, analysis and three-dimensional modelling of the shallow subsurface, a better understanding of contaminant pathways and uncertainties can therefore be achieved.

Understanding fluid flow in fold and thrust belts has the potential to offer enormous insight into hydrocarbon accumulations in regions dominated by such structurally complex settings. Thrusting episodes can be key in creating a complete petroleum system, aiding maturation through burial, developing trapping scenarios, creating pathways for flow though juxtaposition and acting as conduits for flow connecting source to reservoir. The ability to model thrust and fold belts is limited due to the complex nature of threedimensional modelling of thrusts. However recent advancements is structural modelling software have allowed the representation of a stratigraphical surface in two depth locations at a single surface location enabling better realisations of overlain strata in thrust zones. This work simulates the migration of hydrocarbons through fold and thrust zones using new Earth Models of the southern Sub Andean in Bolivia, created from seismic interpretation and well data analysis, and develops a new modelling workflow using multiple geological modelling applications. The migration pathways have been simulated in three dimensions using invasion percolation hydrocarbon migration modelling techniques developed by the Basin Dynamics Research Group at Keele University. These techniques allow the investigation of the relationship of stratal flow properties across thrust blocks. The methodology employed allowed the geological uncertainty of the prospect to be evaluated for hydrocarbon trapping potential, through repeatable simulations where the location point of hydrocarbon source could be controlled. The results of the modelling work provides an insight into the evolution, maturation and potential accumulation of fluids in the Bolivian case study, and has produced a predictive approach to analysing fluid flow and accumulation applicable to other hydrocarbon systems as well as application in other fields considering fluid migration pathways and accumulation.

The Cambrian to Ordovician Durness Group was deposited on the Scottish sector of the passively-subsiding, continental margin of the Laurentian craton, and now forms part of the Hebridean terrane, lying to the west of the Moine Thrust zone. It represents c. 920 m of shallow marine, peritidal carbonates with minor siliciclastic and evaporitic strata. Facies analysis shows that the carbonates represent deposition within coastal sabkha, intertidal and shallow subtidal to shelfal environments and sedimentary logging of all available sections has revised the thicknesses of the lithostratigraphic formations within the Durness Group. A diverse array of microbialites is documented, and their application for interpreting the sea-level and palaeoenvironmental history is discussed. The enigmatic ‘leopard rock’ texture is here concluded to represent a thrombolite, thus significantly increasing the abundance of microbial facies within the section. A revised conodont biostratigraphy for the Ordovician upper five formations of the Durness Group allows more precise correlation with the once contiguous sections in western Newfoundland and Greenland and dating of the lithostratigraphical and sequence stratigraphical subdivisions for the first time. Based upon the new conodont biostratigraphy, a sequence stratigraphical model for the Cambro-Ordovician strata in Scotland is proposed, comprising four depositional megasequences, which correlate well with the Sauk sea level sequence recognised across Laurentia. This study allows for further correlation with Laurentian margin sections and the global sea-level record.

The study attempts to address the tectonic evolution of the Sirte Basin, The seismic work reveal that seven fault zones dominate the area, mostly are NW-SE trending, particularly in the north part, while further to the south a NE-SW trend is noticeable. The thickness variation of the sedimentary fill is extremely affected by these fault zones. The analysis of the tectonic subsidence curves reveals that the tectonic subsidence of the Sirte Basin caused by two rift phases. Initial syn-rift subsidence began in the mid-Cretaceous (~100Ma) and ended at ~84Ma and was followed by slow post-rift subsidence which continued until renewed rifting and rapid syn-rift subsidence at ~65Ma, this phase continued through the Paleocene–Eocene and ceased at ~40Ma, during which ~400–615m of subsidence occurred, after which a second phase of slow post-rift subsidence took place right up to the present. The maximum crustal stretching factor calculated is 1.226 (22.6%). Few numbers of sills intruded into the pre Upper Cretaceous stratigraphic unit probably during the Late Cretaceous rifting. The area dominated by three broad highs anomalies, and a wide depocentre extends NE-SW at the southern part. The study reveals a Moho depth ~26.6–35.8km, and basement depth ranges 4.5-9.5km.

No description available.

Titanite is a calcium titanium silicate accessory mineral that serves as a sink for trace elements, especially the rare-earth elements and the high-field strength elements (Cerny and Rivadisa.L 1972; Groat, Carter et al. 1985; Enami, Suzuki et al. 1993; Perseil and Smith 1995; Della Ventura, Bellatreccia et al. 1999; Piccoli, Candela et al. 2000). It is also characterised by very sluggish diffusion of these elements, and as such it has the ability to resist most sub-solidus alteration. These characteristics make titanite a prime candidate for the ability to preserve a record of the petrogenetic processes which formed the igneous rocks in which it is found. In order to assess titanite’s ability to serve as a petrogenetic tool, a textural and geochemical study of titanite from different igneous environments was undertaken. The Ross of Mull Granite is an igneous complex located on the south west coast of the Isle of Mull, Scotland. It is a Caledonian age pluton that displays evidence of magma-mixing processes at depth and also contains notable amounts of titanite. Samples of different host granite and diorite enclave lithologies and relationships were documented and collected in order to asses the ability of titanite to retain evidence of magma-mixing processes within its compositional zoning. Titanite from the Ross of Mull Granite displays a large variety of textural features, both with respect to crystal shape and compositional zoning. The variation of the trace elements observed in titanite is a direct reflection of the compositional zoning pattern. Melts that are enriched in particular trace elements pass on that signature to the titanites. If melts of significantly contrasting chemistries mix or mingle, then titanite may record any significant instance of trace element diffusion between the melts. More importantly, there doesn’t need to be a transfer of trace elements between mingling/mixing melts for titanite to record evidence of the interaction. If the melts are of significantly different oxygen fugacities, then titanite may become destabilised and partially dissolve. This dissolution may only be temporary, but it may be difficult to tell if it was a product of increasing heat of the melt of if it was due to a change in oxygen fugacity. Titanite however, may record evidence of the cause of dissolution based on the nature of re-growth. As shown by some of the titanites within the Ross of Mull Granite, re-growth following a period of dissolution may be attributed to a change in oxygen fugacity if the new titanite growth is characterised by unusually low REE content. This is related to the nature of trace element incorporation in the titanite structure; REE are taken up due to coupled substitution mechanisms involving tetravalant Al and Fe. If a melt becomes reduced then the activity of ferric Fe will also be reduced, thus inhibiting the ability of titanite to take up REE by affecting the activity of the coupled substitution (Wones 1989; Piccoli, Candela et al. 2000). Titanite from the ROMG is largely characterised by compositional zoning that reflects the trace element chemistry of one of the end-member lithologies (host granite or dioritic enclaves), or has compositional zoning that reflects the changing conditions of the magmatic environment, namely: changes in melt composition, changes in temperature and pressure and changes in oxidation of the magma. In the case of the ROMG, all of these changes were wholly, or in part, brought about by magma mixing processes. Another way in which titanite reflects processes of petrogenesis is that it has been found to reflect the degree of homogenisation of the melt from which it has crystallised. To further asses the ability of titanite serve as a petrogenetic tool, a study was made of the characteristics of titanite from the volcanic environment. The Fish Canyon Tuff, from the San Juan volcanic field, Colorado, USA, was chosen as a suitable candidate for study due to its well documented nature; it is the largest known pyroclastic eruption to be documented. The Fish Canyon tuff also contains numerous phenocrysts of titanite. Eruption of the Fish Canyon Tuff is thought to have been brought about by the thermal rejuvenation of a batholith-sized magma chamber which had previously cooled to a rigid crystal mush (Bachmann and Bergantz 2003). The main conclusion from the study of titanites from the Fish Canyon Tuff and is that evidence for the thermal rejuvenation of the magma chamber by a mafic melt prior to eruption is preserved in the textural and chemical signature preserved in the compositional zoning of the titanites as dissolution and re-growth textures. This study illustrates that titanite is able to not only preserve evidence of magma mixing processes occurring at depth, but it is also able to preserve evidence of similar processes all the way through to the volcanic environment.

Mineral and rock chemistry together with petrography have been used in association with previously determined field relationships to elucidate magma genesis, conditions of crystallisation and geotectonic environment of the appinite suite of western Scotland and northwestern Ireland. The major part of the atudy has been related to the type area of this suite, that of the Ballachulish district in the parish of Appin. In addition, the major cluster of appinites in the Loch Lomond district has been studied together with appinites from Colonsay and Ardara, Dongal. Comparison has been made with the scyelite-pyroxenite-appinitic type rock association of Central Sutherland and with the lamprophyres of the Ballachulish district and lavas of Old Red Sandstone age (late Silurian) in western Scotland. These comparative studies have been used to establish which products of the late Caledonian igneous activity were comagmatic and to determine whether the appinite suite of the type area developed under unique conditions or whether comparable maema genesis, emplacement and crystallisation conditions were widespread in Caledonideso The appinite suite of western Scotland and northwestern Ireland was developed from a volatile-rich basaltic magma. For the :Ballachulish cluster the magma. was of high-potassium calc-alkaline type and evolved towards a relatively continental environment. For the Ardara cluster it was transitional between calc-alkaline and tholeiitic and evolved towards an island arc environment while for the Loch Lomond cluster it was a normal calc-alkaline type evolved in environments intermediate between the other two. In the Ballachulish appinite suite, olivine appeared on the liquidus at about 70-80 km depth. Subsequently emplacement into high crustal level occurred. With magma uprise being impeded by structural traps of the folded Dalradian Supergroup, the rest of crystallisation occurred under decreasing temperature but highly variable PGas due to explosive activity in the subvolcanic pipes. Following olivine, the successive fractionation of clinopyroxene, amphibole, mica and plagioclase led to the progressive development of rocks from ultramafic to acidic compositions. In addition, accumulation of mafic phases occurred in the early st8.$'9sof fractionation, under increasing PGas which led to explosive activity that disrupted the early formed cumulates followed by their upward movement as large "blocks", crystal mushes and individual crystals with variable proportions of the residual liquid. Thus, appinites, kentallenites and even diorites represent "mixed rocks" in which particular phenocrysts are not in a matrix representing the particular liquid with which they were in equilibrium. Explosive activity associated with the emplacement of the marginal ultramafic rocks, appinites and majority of the diorites occurred at higher PGas (4-5 kb) than that associated with the emplacement of kenta1lenites (1 kb). The late leucocratic diorites and granodioritea represent crystallisation from a residual liquid which probably also contained a small component of a hybrid secondary liquid produced by the solution of silica from quartzite, which formed structural traps, at high P-T. Gas-streaming continued after igneous emplacement of various rock types. Corresponding petrogenetic processes were also responsible for the development of the Loch Lomond and Ardara clusters. However, due to the variable strengths of the structural traps, in the Loch Lomond cluster PGas reached before explosive breaching of the traps was generally not so high as at Eallachulish while in the Ardara cluster it was higher than both of the other two clusters. The lamprophyres and lavas of the Old Red Sandstone age (late Silurian) are genetically related to the appinite suite. The scyelite-pyroxenite-appinitic type rock association of Sutherland does not represent a cognate petrogenetic suite of rocks. Scyelite and Si02-poor appinitic type rocks are the products of crystallisation differentiation from a basaltic ma~ and are genetically related to the appinite suite. Pyroxenites and Si02-rich appinitic type rocks represent the hybrids of Ach'uain type. The basaltic magma from which the various appinite clusters crystallised were mantle-derived, at depths of ~o200 km and associated with a northwestward dipping subduction zone in late Silurian time, i.e. in the latter stages of the Caledonian orogeny .