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Despite the significant geothermal resource in the UK, only one small scale scheme in Southampton is presently operating. Few wells have been drilled to target deep resources, particularly in the Cheshire Basin where only two wells have penetrated depths approaching 3 km. As a result, the knowledge of aquifer quality in the more central parts of the basin is limited, meaning there is a high geological risk associated to any geothermal development. To investigate this, a single well model was designed to simulate the extraction of fluid from the Collyhurst Sandstone Formation. Simulations of a range of geological and engineering parameters highlighted hydraulic conductivity could be the most significant obstacle to production, however, it could be minimised by altering engineering parameters (i.e., production rate, length and position of the well screen). A key issue with conventional extraction only methods is the disposal of waste water. To circumvent this issue, innovative deep borehole heat exchangers and standing column wells were modelled. Results indicated that both methods can produce heat loads up to 3.7 MW for short periods. Further analysis was also undertaken on heat exchangers, highlighting significant savings could be made from switching to a geothermal run heat network (>£49 million).

The Archaean Yalgoo-Singleton greenstone belt (YSGB) represents one of the most understudied supracrustal complexes in the well renowned Yilgarn Craton, Western Australia. Despite being highly prospective for various mineral deposit types and host to several gold deposits, the stratigraphy, structure, geochemistry and ages of rocks in the YSGB remains poorly understood. This study utilises a combination of mapping, petrography, geochemistry, and geochronology to better constrain the development of rocks in the YSGB. Drillcore logging, SEM analysis and stable isotope analysis has determined the style, paragenesis and controls on lode-gold mineralisation in the belt. Detailed mapping shows that the YSGB comprises a lower succession of mafic-ultramafic volcanic rocks, overlain by a sedimentary-dominated succession, and extensively intruded by layered, maficultramafic sills. Geochemical analysis has distinguished multiple distinct volcanic and intrusive subgroups within the stratigraphy, which exhibit geochemical evidence of variable degrees of crustal contamination and fractional crystallisation. U-Pb zircon geochronology has constrained the ages of several previously undated supracrustal units and demonstrates the rapid formation of the greenstone belt over a short interval of < 15 Ma, from ca. 2825-2810 Ma. Coupled geochronology and geochemistry has enabled the correlation of units within the YSGB across the region. This study has established a seven-stage deformational model for rocks in the YSGB, recording a progression from bulk extension that accommodated volcanism, sedimentation, and sill emplacement, to a period of extensive granitic diapirism, followed by bulk horizontal shortening and associated shearing, and successive brittle faulting episodes. Lode-gold deposits in the YSGB are invariably structurally-controlled and were emplaced along steeply-dipping shear zones associated with fluid overpressure, during horizontal shortening. The remarkable consistency of structural style, paragenesis and stable isotope signatures at lode-gold deposits is indicative of a single, widespread mineralising event. The age of lode-gold mineralisation in the belt has been constrained at ca. 2623 Ma.

Cryoconite holes are miniature freshwater ecosystems on glacier surfaces worldwide that harbour a diverse microbial community. Microbial isolates from cryoconite holes show exceptional environmental tolerance: they are able to grow in a wide range of pH, high salinities and scavenge a wide range of organic carbon sources. All the isolates tested were facultative anaerobes The community resilience exceeds the 'normal' conditions encountered, and enables their functionality in microenvironments, and in transition environments caused by freeze-thaw. This study demonstrates for the first time that environmental conditions, in particular concentrations of oxygen, are spatially heterogenous at the microscale. Anoxic zones develop rapidly following disturbance and can be found inside cryoconite granules and in thick layers of cryoconite sediment. These microhabitats, with limited oxygen, create microniches for anaerobic metabolism. Facultatively anaerobic microorganisms isolated from cryoconite holes are capable of anaerobic biodegradation via fermentation, and anaerobic metabolism in the holes is dominated by fermentation. An excess of fermentation products, especially acetate, can be detected in defrosted cryoconite sediments and in long-term incubations, indicating incomplete metabolic pathways. Analysis of the microbial community structure revealed that terminal oxidisers are present in low abundance in some of the samples, but the terminal metabolic steps such as sulphate reduction or methanogenesis are not coupled with fermentation. This means that fermentation products could be released to downstream environments, but the extent and impact of this process requires further quantification. Anaerobic metabolism and anaerobic microorganisms are therefore important components of cryoconite ecosystem, which degrade organic matter and impact the glacier carbon cycle.

Mantle convection models are now well established as a tool for addressing geochemical problems. This thesis focusses on understanding the processes which affect long-standing observations relating to the U-Th-Pb, K-Ar and He isotope systems. Pb isotope ratios display a linear trend in 207Pb/204Pb vs 206Pb/204Pb space, the gradient of which corresponds to the pseudo-isochron age. Scatter in the data also encodes information about differentiation which has not previously been considered. The problem is addressed by including processes which have not been incorporated into geodynamic models before, allowing for the timing and magnitude of different fractionation processes to be investigated. A combination of preferential removal of Pb from the mantle after 3.0 Ga and recycling of U from the continental reservoir after 2.4 Ga achieves a higher degree of scatter than previous modelling methods whilst maintaining a pseudo-isochron age similar to mantle derived rocks. Noble gases constrain mantle degassing from the 40Ar/36Ar composition of the atmosphere and the degassing rate of primordial 3 He. The noble gas composition of oceanic basalts provides additional constraints on mantle convection models. The degassing efficiency of the mantle, dynamic effects, and the initial distribution of trace elements in the mantle are all considered for the effect they have on the noble gas composition of mantle derived rocks and the atmosphere. Recycling of noble gases (incomplete degassing) and high degrees of processing are shown to be important for the development of MORB-like helium ratios. In the standard model setup the present day flux of 3 He is higher than what is predicted for Earth but can be reduced through increased processing, increased degassing efficiency or increased segregation of basalt to the lower mantle. It is shown that an Earth-like atmospheric 40Ar/36Ar can be achieved through a combination of mantle and continental crust degassing, provided the system is sufficiently enriched in 36Ar. A model initialised with a heterogeneous distribution of trace elements can produce the range of helium ratios observed in Ocean Island Basalts. The Pb pseudo-isochron age and associated scatter are not directly correlated to the density of basalt in the lower mantle, but to consequences of increased basalt density. Re-melting times generally get longer for excess lower mantle basalt densities greater than 4% (relative to harzburgite) and for longer re-melting times the Pb pseudo-isochron age increases. The degree of scatter correlates to the fraction of recycled basaltic material which constitutes the melt, which in turn has a non-linear dependency on the lower mantle density of basalt.

Sea surface temperatures approach but rarely exceed 30°C in the Indo-Pacific Warm Pool, the hottest region of the modern open ocean. Climate models with reconstructed continental configurations and elevated CO2 concentrations suggest that an Indo-Pacific Warm Pool has existed since the Mesozoic but virtually no reliable paleotemperature proxy data from the region exist, partly due to the rarity of finding exceptionally preserved foraminifera from deep time. Models suggest that temperatures in the Warm Pool may have become extremely hot, up to 40°C, during warm climate phases such as the early Eocene, potentially exceeding the tolerance limit of eukaryotic life. As part of this study, a thorough exploration of “legacy” samples archived in the British Petroleum (BP) foraminiferal collections at the Natural History Museum, London, was conducted to search for material suitable for geochemical analysis. This yielded an important sample from the early Eocene of Papua New Guinea which was analysed as well as material from the late Eocene of Java that was collected in a previous expedition. New oxygen and carbon isotope data are presented from both the early and late Eocene planktonic foraminifera, alongside Mg/Ca for paleotemperature reconstructions from the early Eocene. The study samples contained exceptionally well-preserved (“glassy”) foraminifera but suffered from diagenetic infilling by late stage calcite. By the innovative method of crushing the samples and carefully separating foraminiferal test fragments from the infill it was possible to obtain reliable geochemical data from a variety of mixed layer and thermocline species, as well as one data point from benthic foraminifera for both the early Eocene and late Eocene. The successful outcome of the separation was confirmed by the infill consistently having lower δ18O values than its associated original test, which is indicative of the influence of meteoric waters. Eocene sea surface temperatures were derived from Papua New Guinea, and measured ~32-35°C, which is several degrees warmer than comparable early Eocene data from a similar latitude in Tanzania. Thus, the data support the presence of a moderately hot Warm Pool in the early Eocene which supported an abundant and diverse eukaryotic plankton community. Considering that modelled palaeogeographies positioned early Eocene Papua New Guinea at ~29°S, the results are still several degrees warmer than modern Warm Pool temperatures. This suggests there were even higher temperatures at the core of the early Eocene Warm Pool. Late Eocene temperatures were retrieved from Java which was positioned in the tropics (0.54°N), and recorded sea surface temperatures of 37°C while still hosting a diverse and abundant foraminiferal assemblage. When simulating the Eocene temperatures on the palaeoclimate models under 1120 ppm of atmospheric CO2, the results from late Eocene Java matched the model outputs better than early Eocene Papua New Guinea, as the temperatures of the latter were underestimated to a greater extent by the models. This may be due to either the presence of higher than 1120 ppm atmospheric CO2 concentrations in the early Eocene, which would have increased the simulated temperatures of the climate model, or a higher climate sensitivity during the early Eocene due to the intensified hydrological cycle typical of this interval which would have increased the amount of tropical cyclones transferring heat from the tropics to higher latitudes.

Seismic interpretation and attribute analysis of three-dimensional seismic data often reveals focused fluid flow features such as pockmarks, mud volcanoes, hydrothermal vent complexes and amplitude anomalies. This thesis analyses three distinct data volumes from the Jæren High (Central North Sea), East Breaks area (northern Gulf of Mexico Basin), and Vøring Basin (mid-Norwegian margin), where fluid flow features are observed. The three study areas reveal a variety of these features across a range of depths and associated structures within sedimentary basins, from salt walls and pods, to salt minibasins and magmatic sill complexes. Thus, this thesis aims to improve our understanding of fluid migration in sedimentary basins and discuss the impact of the results on the hydrocarbon industry. A comprehensive seismic and borehole dataset from the Jæren High is used to investigate the distribution and timing of buried pipes and pockmarks, which reveal seal breach across salt welds and Mesozoic strata. A semi-automated method in ArcGIS is used to map and characterise 196 depressions in three seismic surfaces. Depressions range in width from 225 m to 842 m and in vertical relief from 14 m to 178 m, scales that are comparable with the literature but that expand the limited evidence of large, 'mega' pockmarks, particularly in buried strata at the depth of prolific hydrocarbon reservoirs. It is shown that Upper Cretaceous depressions are likely to be drape features and pockmarks formed during the Upper Jurassic and Lower Cretaceous. Burial history modelling reveals gas maturity in Carboniferous strata, which may have sourced the observed pockmarks. High-amplitude anomalies within- and outside of pipes suggest further fluid seepage across salt welds, a character increasing the risk of seal breaching on the Jæren High if this structure is considered as a carbon capture and storage site. Data from the East Breaks area of the northern Gulf of Mexico Basin are used to analyse the morphology and distribution of 720 pockmarks and 62 mud volcanoes on the sea floor, correlating these with underlying structures and source intervals in a major salt province. Salt diapirs and associated crestal faults are the main fluid focusing pathways, whilst high-amplitude anomalies in salt minibasins may indicate gas pockets or hydrocarbons that have not leaked to the sea floor. The relationship between the depth of fluid source and size of pockmarks and mud volcanoes is deemed complex, in contrast to the expected correlation between increasing pockmark size and depth of source. In fact, the shallow plumbing system in East Breaks is dominated by pockmarks, whilst mud volcanoes are sourced from the deeper parts of the salt minibasins. The influence of magmatic sills, dykes and hydrothermal vent complexes on fluid migration is explored in the Modgunn Arch dataset from the southern Vøring Basin, Norwegian Sea. A total of 85 buried hydrothermal vent complexes are mapped, from which three examples of stacked vent complexes are identified, indicating important reactivation of existing conduits. Amplitude anomalies in younger strata suggest later-stage fluid seepage across hydrothermal vent complexes, highlighting the importance of magmatic structures in controlling fluid migration pathways. Larger vents tend to be fed by deeper sills, while a greater proportion of the larger vents are associated with amplitude anomalies. In conclusion, the presence of pipes, conduits and faults weaken or strengthen the host rock, depending on the in-situ stress states and cementation of these pathways. This will impact the degree of overpressure increase required for modern day reactivation of these pathways. As a result, this thesis explores the complexity of focused fluid migration pathways through sedimentary basins with the aim of understanding the importance of subtle features on seismic data as recurrent fluid flow paths. These are important considerations when exploring in challenging geological environments such as salt-rich and magmatic basins, as well as when identifying sites suitable for carbon capture and storage.

Large earthquakes are significant geomorphic events in mountain ranges;they can cause uplift while also triggering huge volumes of bedrock landsliding. Constraining theerosion of coseismic landslide deposits is important forunderstandingthe long-term impact of earthquakes on landscape evolution and natural hazards. The 2008 Mw7.9 Wenchuan earthquake provides an excellent opportunity to constrain the processes and rates that erode landslide deposits within and out of mountain catchments. I constructed a large multitemporal landslide inventory of the epicentral regionof the earthquaketo map the erosion of landslide deposits in the 10 years after the earthquake. In these 10 years less than 13% of the sediment hadbeen deposited into the stores associated with the main trunk of the orogen draining river leaving up to 88% stored on the hillslope. Debris flows were the key remobilising process, transporting over 50% of all the sediment that is mobilised. Using slope stability modelling and analysis of the landslide inventory I identified most of the debris flows were triggered on the hill slope and their frequency decreased rapidly through time. Initially debris flows were triggered in small deposits with low drainage areasbut through time the landslides closer to channel network become more likely to be the source of debris flow activity, a pattern that highlights a change in the physical properties of the deposits. I evaluate several theories that may explain this pattern and highlight strategies to identify the stabilising processes. Finally, I present a 0-Dimensional model investigatingthe impact of storage of coseismic sediment on landscape evolution. This model suggests coseismic sediment can remain in the mountain range for timescales greater than the recurrence time of large earthquakes causing a decrease in exhumation ratesas sediment is remobilised. The long storage time of sediment in orogens reduces the impact of earthquakes on long term (>1000 years) exhumation records so that single earthquakes are only recorded in the most local or highest resolution records.

Fault zones are dynamic sites of deformation and reactivation that partition strain throughout the Earth’s crust. Their nucleation and growth in the upper crust is often associated with economically important fluid flow, which is of particular importance in low-permeability host rocks that require brittle deformation to create interconnected permeability networks. Fault zones in gneissose basement complexes have been increasingly recognised as economically significant structures in the hydrocarbon and geothermal sectors due their ability to act as fluid conduits and/ or barriers. Their hydraulic properties and permeability structures are also important in environmental and alternative energy sectors. Carbon-capture and storage will be vital and necessary to mitigate the effects of the climate crisis. Joint industry, academia and government-funded projects such as Carbfix are currently exploring the potential for basement gneiss complexes to sequester CO2. With regards to alternative energy such as nuclear power, which generates significant amounts of hazardous waste, many deep geological repositories in gneissose basement and granitic intrusions are currently operational or are being considered by many countries. Comprehensively characterising the structural framework of complexes with long-lived deformation histories is therefore crucial for assessing their attributes as reservoirs and seals of fluids in the subsurface. There is a need to develop a conceptual model that describes attributes of fault zones that cross-cut basement gneisses. The key questions that inspired this research are: i) What are predictable fault zone characteristics of basement-hosted faults throughout the upper crust? ii) How do fluids influence basement fault rheology and deformation processes, throughout the upper crust? iii) What effect does fluid-rock interaction have on host rock and basement fault zone properties? Two well-exposed major fault zones, the Outer Hebrides Fault Zone (OHFZ), Scotland, and the Bwamba Fault Zone (BFZ), Rwenzori Mountains, Uganda, have been studied. Additionally, minor faults that populate the basement gneiss complex that forms the Rwenzori Mountains were studied. These fault zones are all characterised by similar host-rock compositions and are known to be important with regards to upper crustal fluid flow. The OHFZ represents a “deep” upper crustal fault zone, whilst the BFZ represents a shallower upper crustal fault zone, and the investigation presents a comparison between fault zones at different crustal levels. The BFZ is juxtaposed against a sedimentary basin in it’s hanging wall, and so provides a useful analogue for hydrocarbon systems, both locally in the East African Rift System, and for general buried hill-type hydrocarbon plays. Minor faults of the Rwenzori Mountains have developed at various times, in both deep and shallow upper crustal conditions. This network of variably oriented faults are investigasted to assess the potential for fluid migration throughout interconnected fault networks in gneissose basement complexes. A field-based approach to developing kinematic models of basement faults in both the OHFZ and the BFZ is coupled with microstructural and geochemical analyses to determine structural and fluid-rock interaction textures. Optical and scanning electron microscopy is used to analyse the petrography, structure and geochemistry of the fault rocks of the BFZ. Furthermore, X-ray computed microtomography allows fault zone mineralisation and porosity structure to be visualised in three dimensions, and provides insight into large scale fluid pathways within the BFZ. Stable isotope analysis is used determine the source and temperature of fluid ingress to the BFZ, and constrain hydraulic connectivity between the basement fault and the hanging-wall basin. Optical microscopy and quantitative evaluation of minerals by scanning electron microscopy (QEMSCAN) is undertaken in order to characterise ultra-fine-grained samples of the OHFZ. Results indicate that in deep upper crustal fault zones in the OHFZ, and some minor faults studied in western Uganda, basement faults are composed of interconnected cataclasite networks composed of greenschist-facies mineral assemblages of albite, epidote, muscovite and actinolite. These phases also form within altered wall-rock, and replace significant volumes of the original mineralogy of the gneissose host. High strain zones are composed of albite, epidote, actinolite and quartz cataclasites with very fine grain sizes < 20 μm. Matrix-forming albite often shows strong shape preferred orientations, and epidote, actinolite, muscovite, chlorite and illite are aligned along S-C` fabrics. A significant result from the OHFZ is that rocks traditionally thought to be phyllonites contain < 6 vol % of phyllosilicate phases, and are instead composed largely of strongly foliated albite, quartz, epidote and actinolite cataclasites. The BFZ is considered to be representative of deformation at shallower formation depths in the upper crust between 4-7 km. It is composed of banded quartzo-feldspathic cataclasites that have well-developed Riedel, Y- and P-foliations. These are sites of localised grain size reduction and commonly host haematite mineralisation. Mineralisation of these structural fabrics has resulted in the formation of rhombohedral compartments, within which fault rocks have undergone variable amounts of haematite and jarosite mineralisation. Many compartments remain porous. The host gneisses do not contain significant Fe- or S-bearing phases, but adjacent hanging wall basins are rich in gypsiferous, iron-rich mudstones. Calculations of sulphur and oxygen isotopic signatures of mineralising fluids were derived from haematite (δ18O) and jarosite (δ34) isotopic analyses from the BFZ. These are consistent with a rock buffered diagenetic fluid origin. Faults analyses from minor upper crustal faults of the northern Rwenzori ridge indicate fault orientations and kinematics both consistent with the regional extensional stress field of the East African Rift System, and faults oriented at high angle to the rift axis that host strike-slip and reverse motion. These faults are characterised by loose breccias and strongly foliated clay-gouges with Riedel, Y-, and P- foliations, or by slickenside-surfaces that lack fault rock development. Basement gneiss complexes analysed in this study experience a complex history of faulting and reactivation during exhumation, with broad similarities in fluid rock-interaction and rheological evolution of the faults: i) Deformation and structural fabrics such is Riedel, P- and Y-shears, and S-C` fabrics represent primary fluid pathways, as indicated by the spatial distribution of fluid-rock interaction textures in optical and scanning electron microscopy, and through XCT analyses. Brittle deformation facilitates both grain size reduction and fluid ingress. This results in compartmentalisation due to mineralisation of these fabrics, or strain-softening under periodic high-fluid pressures. ii) Intra-granular and grain boundary fluid influx promotes widespread alteration of the wall rock, and clasts within the fault core and represents an effective secondary control. Fluid-rock interaction in the host rock triggers mineral replacement reactions and products may either crystallise within pore-fluid, or are removed in solution via fractures. iii) Rheology changes are strongly linked to fluid-influx in basement faults. These reflect changes in mineralogy, e.g. due to the formation phyllosilicate networks, but also high fluid pressures, the development of fault fabrics, and grain size reduction. iv) Basement faults with adjacent hanging-wall sedimentary rocks act as transient basin fluid conduits in tectonically active basins. Petrographic and microstructural analyses of fault zone mineralisation products coupled with stable isotope analyses can constrain the origins of fluids and highlight hydraulic connections with sedimentary rocks in hanging-wall basins. v) Basement gneiss complexes respond to both regional and local stresses in syn-rift settings and may host cross-cutting faults that create interconnected permeability networks. Such networks may be of importance for regional fluid flow in economically important basins. Basement gneiss complexes present many exciting opportunities for meeting the energy demands of a growing global population, and have potential to offer solutions in storage of hazardous waste and CO2 as humanity addresses the energy transition away from fossil fuels and the climate crisis. It is therefore integral that comprehensive knowledge of basement fault systems is understood in order to meet these challenges, and this project contributes something toward these goals.

The study of climate parameters and their feedback mechanisms have become exceedingly important in light of anthropogenic CO2 release and its initiation of climate change. In this thesis, I investigate the interaction between different climate parameters during Late Pleistocene climate cycles and the Mid-Pleistocene transition(MPT). I use ocean sediment core-derived foraminiferal shells and geochemical analyses to reconstruct surface water temperature, salinity, and atmospheric CO2 from a new site U1476 in the Mozambique Channel. I show for the first time that a peak in glacial Indian Ocean surface salinity creates a particularly salty Agulhas Leakage during Late Pleistocene deglaciations. This may influence changes in global climate by altering the surface salinity budgets at deep water convection sites, potentially driving a more vigorous overturning circulation. Late Pleistocene climate transitions established during the MPT “900kyr event”, when glacial ice volume significantly increased forming a 100kyr cycle. I demonstrate that ice sheets during the early MPT sustained glacial ice volume, despite increases in summer duration insolation and temperature. The data combined with new pCO2 reconstructions suggest that the early de-coupling of ice sheet dynamics caused a disruption in the forcing of earth’s internal feedback mechanisms, leading to the global phenomenon of the “900kyr event”. The pCO2 data was reconstructed using multi-collector inductively coupled plasma mass spectrometry (MC-ICPMS) boron isotope analysis. I present accuracy and precision data of boron isotope standard measurements conducted on a new Nu plasma II instrument. Best results were achieved after adopting a PFA cyclonic spray chamber, 1011Ω resistors, and concentrated solutions. My additional laboratory test studies provide evidence that cleaning large samples, as used in boron isotope analyses, can be efficiently conducted without the necessity for scaling reagents. My research concludes that Late Pleistocene Indian Ocean circulation and early Pleistocene ice sheet dynamics are important internal climate drivers that have the potential for shaping Pleistocene climate when coupled with insolation - or atmospheric CO2 change.

Scotland is part of the NE Atlantic passive margin with geological features and land- scapes that are evidence of a long and complex geological history. A prolonged period of extension, related to the rifting and breakup of Pangea, began in the Late Carbonif- erous and continued through the Mesozoic until breakup and the formation of oceanic crust occurred in the NE Atlantic in the Early Cenozoic. There is evidence that the Scottish landscape and surrounding basins experienced significant uplift in the Early Paleogene. However, whether this uplift can be attributed to tectonic processes re- lated to rifting or to the movement of the hot Iceland mantle plume past the west of Scotland and Northern Ireland at around 65 Ma, is still unresolved. It also remains unknown to what degree the Caledonian Highland mountains in northern Scotland, produced during the Caledonian Orogeny in the Late Devonian, have retained their original topography since they formed. To investigate long term rates of landscape evolution temporally and spatially across Scotland it is essential to constrain the timing and both the rate and amount of denudation during different stages following the Caledonian Orogeny to determine the more likely cause of uplift and erosion, especially in Late Cretaceous-Early Palaeogene. For that, this study employs apatite fission track and apatite (U-Th-Sm)/He thermochronology on samples collected from vertical profiles and from a regional NW- SE transect from the Outer Hebrides in the west towards the central and eastern Grampian Highland. In total 51 rock samples were collected. AFT analysis was performed for 50 of them using EDM and LA-ICP-MS recently installed at the University of Glasgow. For AHe analysis, 281 grains were analysed in total. During the analysis the single grain ap- proach was performed, and the new approach of treating broken grains introduced by Brown et al. (2013) and Beucher et al. (2013) was performed when samples were modelled using QTQt (5.7.0). In addition, the most recent algorithm of Gautheron et al. (2009) and Flowers et al. (2009) for radiation damage effect were incorporated to model AHe data, and Dpar was used to account for impact of chemical composition on fission track annealing. Along the study area from west to east AFT ages vary between 297.9±29.4 to 166±16.7 Ma, and the oldest age has been observed in the Central Highland. AHe mean ages are between 237.1±72.8 and 19.9±4.1 Ma. The oldest AHe mean ages have been recorded by areas around Cairngorms and Lochnagar, especially top of Lochnagar sample has provided the oldest AHe mean age across the study area. Generally measured mean track lengths varies between 11.11μm to 13.04μm along the study area, and the short- est mean track lengths have been recorded in the area around the Cairngorms. Length projection process increased mean track lengths and the maximum mean track lengths reached 14.21μm in the Outer Hebrides, and 13.99μm for the high elevation samples from the vertical profiles in the Grampian Highlands. Thermal history modelling, including the individual thermal models and joint thermal models for vertical profiles, suggest that the Scottish landscape has experienced several cooling pulses following the Caledonian Orogeny; Mid to Late Devonian (380-360 Ma), Late Carboniferous-Early Triassic (c.300-250 Ma), Early to Mid Cretaceous (120-100 Ma), and Late-Cretaceous-Early Paleogene pulse (c.80-60 Ma). Based on the predicted cooling pulses the Scottish landscape has been divided into three separate regions, the Outer Hebrides, east of the Grampian region, and west of the Grampian region. The first cooling pulse which is the oldest cooling pulse across the study area has only been predicted by samples collected around the Cairngorms, and Lochnagar (east of the Grampian Highlands). It is interpreted as an erosional cooling pulse initiated following the Caledonian Orogeny and is linked to isostatic uplift after orogenic crustal thicken- ning and granite intrusion during the Caledonian Orogeny. The Second cooling pulse seems to be regional as it has been predicted by almost all samples across the study area. Event though this pulse starts in some samples at the end of Carboniferous, majority of the samples have suggested Permian into Triassic. This pulse of cooling is coeval with the erosion and deposition of significant amount of Permo-Trassic sed- iments in the basins around Scotland (e.g. Minch Basin, Sea of the Hebrides Basin, Moray Firth Basin). During Late Permian-Early Triassic to Early Cretaceous Scotland has been through monotonic cooling and erosion based on the derived thermal models in this study. During this period uplift should have been less than the earlier pulse but the Scottish Highland has kept feeding the surrounding basins but at lower rates. The Early to Mid Cretaceous pulse which has been only observed from the vertical profile samples in the Grampian Highland region (e.g. Ben Starav, Aonach Mor, and Lochnagar) is synchronous with continental break up and sea floor spreading in the Central Atlantic region and associated rift propagation to the NE Atlantic region. Before the last cooling pulse starts, the east and west coast of the Scottish Highland possibly have been buried due to marine transgression and deposition of chalk which reached a peak at around Campanian (c. 80 Ma). Following that, the last cooling pulse starts in Late Cretaceous-Early Paleogene based on the new derived thermal models. This pulse is more likely to be linked to the proto Iceland mantle processes (including dynamic up- lift, thermal perturbation, and magmatic underplating) rather than far field stress from the continental break up at around 55 Ma, based on the time of cooling and spatial distribution of denudation associated with this pulse. However, it is clear that other geological factors like lithology and possibly fault reac- tivation have controlled the local denudation amount, therefore there is not a smooth transition in denudation amount from west to east, but still the interior part has been affected by less uplift and denudation in Late Cretaceous-early Palaeogene compared with the western regions. The arrival of hot material from the Iceland mantle pulse might be expected to have changed the thermal temperature regime at least in the west part of Scotland, but the calculated thermal gradients in this study shows that the thermal regime has not been perturbed in Late Cretaceous-Early Palaeogene when the cooling started. This is possibly because the arrival of hot mantle material and magmatism from the Iceland mantle plume stayed the the lower most part of the crust, as only when it intrudes at shallow crustal level, can it make a significant perturbation to the temperature regime in the upper most crust.

Ancient and contemporary aeolian systems have been subject of important conceptual advances in recent years, however, a disconnect exists between the complexities inherent at the depositional surface and subsequent controls on preservation. At the fundamental level, the depositional environment consists of dune-fields, and the rock record is a stratigraphic architecture consisting of cross-strata and bounding surfaces. Vast outcrops of ancient aeolian strata display huge amounts of temporal variation manifest through dune-field evolution while the sedimentary record of contemporary ergs remain largely unknown. In order to bridge these gaps this research utilises a range of digitally based systems and techniques to analyse spatial data in order to unravel contemporary and ancient system evolutions. The study utilised the Wahiba Sand Sea of Oman and the Jurassic Navajo Sandstone of western USA as contemporary and ancient analogues respectively. Analysis of high to medium-resolution satellite and geophysical datasets demonstrate that antecedent topography has been a dominating allogenic boundary condition during the formation and growth of large linear bedforms in the Wahiba Erg. There appears to be a hierarchy of autogenic processes influenced by antecedent topography that imparts a uniqueness to the emergent dune-field pattern. The production of large-scale virtual outcrop models permitted broad spatial analysis of three sites across the Navajo Sandstone which represent marginal through central erg settings. Results show unique allogenic controls relating to system architectures at each outcrop, some of which provide validations to hypotheses made from observations within the contemporary analogue. The research demonstrates that in extracting signals of allogenic boundary conditions within which autogenic system processes evolved is the basis for the interpretation of geomorphic landforms and their stratigraphic record. The analogues represent a point on a spectrum of preservations styles recently detected in aeolian systems and provide additional examples with which to advance our knowledge.

Arc magmas typically show distinct geochemical and petrographical evidence indicating a complex petrogenesis. The surface products represent a summation of the complex interplay of geodynamic magma generation processes, varied differentiation histories, and crustal interaction. Xenoliths, ‘foreign rocks’, are found in the deposits of most volcanoes worldwide, and represent snapshots of individual events occuring during magmatic petrogenesis. Crustal xenoliths record the interaction between magma and the surrounding wall-rock, whilst plutonic xenoliths record the magma generation and differentiation history. This work uses two case study volcanoes: Merapi in the Indonesian Sunda Arc to focus on calc-silicate crustal xenoliths, and Santorini in the central South Aegean Volcanic Arc to focus on plutonic xenoliths. The calc-silicate xenoliths at Merapi record magma carbonate interaction processes. Thermobarometric calculations, fluid inclusion microthermometry and newly calibrated oxybarometry based on Fe3+/ΣFe in clinopyroxene indicate xenolith formation conditions of ~510-910 ± 45°C, < 100 MPa and at an oxygen fugacity between the NNO buffer and air. Halogen, sulphur and copper-bearing minerals show magmatic brine infiltration and the early stages of economic mineral deposition. Assessment of the timescales of xenolith formation and crustal CO2 liberation demonstrates that magma-carbonate interaction could affect eruption intensity, and at a larger scale, impact global carbon cycling. The plutonic xenoliths at Santorini can be considered cumulates to the magmatic system. Their whole-rock, melt inclusion and intercumulus glass chemistry shows they are representative of the entire liquid line of descent. Thermobarometry indicates they formed over a wide temperature range between ~1100 to 750°C, at shallow to mid crustal depths (< 400 MPa) from a partially differentiated deep crustal melt. These pressures are shallower than those estimated for the East and West South Aegean Arc. Early melts extracted from the cumulates produce liquids comparable to the volcanic whole-rocks, but some samples show extensive post-cumulus crystallisation, and generation of evolved trapped liquids that may only interact during cumulate remobilisation episodes. Together, these case studies demonstrate that xenoliths are powerful tracers of individual processes that define the complex geochemical signatures occuring at arc volcanoes. Although xenoliths may not be present in all volcanic deposits of all volcanoes, the understanding gained from studies such as this are applicable worldwide.

Tetrapods (four-limbed vertebrates) invaded the land more than 370 million years ago and began to diversify into a spectacular range of morphologies and life modes, rapidly achieving a global distribution. However, due to the inherent temporal and spatial bias of the fossil record, global patterns of tetrapod diversity and biogeography during critical intervals of the group's evolution remain unresolved. This thesis focuses on examining the patterns and drivers of tetrapod diversity during two of these key intervals. Firstly, advanced statistical, phylogenetic, and modelling approaches were used to examine the impact of major environmental change on the first tetrapods to emerge onto land during the late Palaeozoic (358-272 million years ago). Next, these approaches were combined with palaeoclimatic reconstructions to examine the influence of climate on tetrapod diversity during the early Mesozoic (237-174 million years ago), when modern vertebrate groups, including the dinosaurs, were originating. Together, the results provide a comprehensive assessment of the impact of sampling biases on estimates of past diversity, as well as providing greater insights into the role of environmental and climate change on tetrapod diversity and biogeography.

Non-avian dinosaurs were a highly successful clade of terrestrial tetrapods that dominated Mesozoic ecosystems. Their public and scientific popularity makes them one of most intensely researched and understood fossil groups. Key to our understanding of their evolutionary history are interpretations of their changing diversity through geological time. However, spatiotemporal changes in fossil specimen completeness, diagnostic quality, and sampling availability can bias our understanding of a group’s fossil record. Methods quantifying the level of skeletal and phylogenetic information available for a fossil group have previously been used to assess potential bias. In this thesis, these methods are used to critically assess the saurischian dinosaur fossil record, including an examination of changes in specimen completeness through research time. Novel metrics are presented that quantify the diagnostic quality of fossil specimens and assemblages. Results suggest that recent changes in our understanding of the dinosaur fossil record mostly derive from taxonomic and stratigraphic revisions. The completeness of the sauropodomorph fossil record is temporally segregated, whereas the theropod record is heavily spatially and environmentally biased, plus shows signs of taphonomic and taxonomic identification bias towards particular subgroups. These results represent a significant contribution to better understanding the nature of the dinosaur fossil record.

Planktonic microfossils recovered from the deep marine shales and marls of the Fiqa Formation, Oman, deposited through ∼15 Ma, from the late Coniacian to earliest Maastrichtian provide a window into Late Cretaceous tropical, pelagic ecosystems. In this thesis I present new records based on well-preserved calcareous nannofossil assemblages and inorganic geochemistry to provide new information on the chronostratigraphic subdivision, palaeoenvironments, high-resolution correlation and sequence stratigraphy of the Fiqa Formation. This study is based on the examination of 341 cuttings and side core samples from 11 hydrocarbon exploration wells distributed across a palaeobathymetric gradient within the Upper Cretaceous Aruma Basin. Results include the first detailed taxonomic analysis of Late Cretaceous nannofossils from the Fiqa Formation including the identification of two new species; a new biozonation scheme for the Fiqa Formation that is correlated into the global UC biozonation scheme of Burnett et al. (1998); new biostratigraphic correlations across the basin and integration with regional sequence stratigraphy; and finally, integration of nannofossil assemblage data with detailed bulk rock carbon isotope and element composition analysis and the reconstruction of long-term palaeoenvironmental change and basin evolution, both in space across Oman and through time.

Revealing the internal composition and evolution of the terrestrial planets is crucial to understanding planetary evolution in the Solar System and beyond. Mars is a perfect source of this information, since its mantle was not homogenized after the earliest phases of planetary differentiation. However, the interior evolution and composition of Mars is still unknown. Martian meteorites are the only rock samples from Mars that are available on Earth. The aim of this research is to obtain new insights about Martian mantle formation and its evolution from the perspective of the Martian meteorites. In particular, this work is divided into three interdisciplinary investigations in order to obtain new constraints on our knowledge about the Martian mantle. Firstly, the Tissint Martian meteorite was investigated since it is the meteorite that is most representative of the Martian mantle. This meteorite was analysed with the objective of obtaining information about the thermal state and convective activity in the Mars’ mantle. Major- and trace-element data for Tissint olivine and pyroxene were reported, and these data were used to provide new insights into the dynamics of the Tissint magma chamber, as well as the dynamics and temperature of Martian mantle at the time of Tissint crystallisation. Secondly, the potential for chemical tracing of the different Martian mantle sources was investigated by analysing rhenium-osmium and sulphur isotope compositions in five of the ten known nakhlite lava flows (Nakhla, Lafayette, MIL 090032, Yamato 000593, and Yamato 000749). In addition, these findings were used to suggest a plausible scenario to account for nakhlite magma origins. These findings were also utilised to discuss the implications of this work for fingerprinting the processes responsible for setting Martian mantle compositions during late-stage crystallization of a Martian magma ocean. Thirdly, the abundance of the volatile element chlorine in the Martian mantle was calculated by analysing amphibole and apatite phases in the two shergottites Tissint and Zagami. After finding that these phases record magmatic conditions of the Martian interior, the partition coefficients between chlorine and the parent melt were used to estimate the chlorine abundance of the shergottite magma source. In sum, the importance of the combined new findings are presented to explore their implications for our understanding of Mars’ formation and evolution and, more generally, the evolution of terrestrial planets.

As a branch of geomorphology, geochronology determines the ages of sediment, fossils, and rocks, thereby assembling a geologic planetary history. As a geochronological dénouement, the proposed geological epoch of the Anthropocene may indicate the figural moment in geologic time when human activity inscribed itself into sediment across the planet. This dissertation offers an artist’s account of practice-as-research investigating how to perform geochronology in the Anthropocene along North Atlantic foreshores. As sites prone to the geologic acts of deposition, erosion, and intrusion, foreshores provide an impermanent surface on which to interrogate the deep time, hidden knowledges, and climate crisis affiliated with the Anthropocene’s inaugural narrative. Geochronologists partly comprising a working group to give the Anthropocene its formal designation note that “[t]he expression of the Anthropocene in the environmentally sensitive coastal systems [including beaches, tidal flats, and deltas]... represents a diverse patchwork of deposits and lacunae that reflect local interplays of natural and anthropogenic forces” (Zalasiewicz, Williams, and Waters 2014). Climate change also places foreshores as central players impacted by storminess, glacial melt, rising sea levels, and ocean acidification. Produced as the book Sound of Mull, the artist’s performance scores were developed through artistic practice-as-research and offer strategies for experiential knowledge acquisition through direct or imagined engagement with the multiple temporalities and more-than-human co-constituents of North Atlantic foreshores. Participatory, experiential engagement may sensitize people to the hidden geochronologies of everyday life. This dissertation is situated within an interdisciplinary practice-as-research methodology integral to geopoetics praxis, interweaving research from performance studies, geology, human geography, and archaeology. Detailing foreshore performances enacted in Denmark, Iceland, Norway, Scotland, and Sweden between 2015 and 2019, the dissertation argues for interdependence and circulation as necessary components defining geopoetics. The account expounds the importance of both interdisciplinary scholarship and artistic practice-as-research methodology in the exploration of geopoetics as transformative action. Research was undertaken through PhD study at the University of Glasgow from 2015 to 2019, supported by the Lord Kelvin / Adam Smith Scholarship.

Exhumed mid-crustal retrograde shear zones provide a rare natural laboratory for investigating the effect of uids on rheology. In active plateboundary retrograde shear zones, geophysical observations have highlighted localised uid-rich structures, at and below the frictional-viscous transition. Because rocks in retrograde metamorphic settings have typically been dehydrated, and mylonitic shear zones are viewed as tabular zones, the wet and localised active shear zones raise questions regarding uid origin, as well as the spatiotemporal distribution of mineral-scale deformation mechanisms within mylonites. This thesis presents field observations, microstructural analyses, oxygen stable isotopes and bulk rock compositions, to investigate two exhumed, mid-crustal, strike-slip shear zones: the Kuckaus Mylonite Zone (KMZ), Namibia, and the Outer Hebrides Fault Zone (OHFZ), Scotland. In the OHFZ, the uid likely originated from magmatic and metamorphic sources, and induced weakening predominantly by facilitating pervasive growth of phyllosilicates within which deformation localised. In the KMZ, at least some of the uids were sourced from the surface, and whereas phyllosilicate growth facilitated incipient weakening, the ultramylonitic cores comprise a fine-grained polyphase mixture deforming by uid enhanced grain size sensitive creep. The greatest effects of uids in retrograde shear zones may be the metasomatism and enhancement of grain size sensitive creep they facilitate. The weakening effect includes replacement of strong minerals by weaker and finer grained phases. Therefore, uid presence may facilitate drastic weakness in mid-crustal, strike-slip shear zones, without elevated uid pressures, by allowing grain size sensitive creep at very low driving stresses in thin (< 1 m) ultramylonites. This weakening may create conditions favourable for low stress drop phenomena, such as slow slip and tremor and provides alternative explanations for such events observed at active plate boundary shear zones.

This study is the first to demonstrate a novel combination of hydrological and biological control of a freshwater lake system. The former through lake flushing rate and the latter through topdown control by an invasive filter-feeder; zebra mussels. The artificial freshwater lake of Cardiff Bay, South Wales was created in 2001 by the implementation of an amenity barrage across the Taff-Ely estuary. To date, management methods include an aeration system to maintain dissolved oxygen concentrations within the water column, and a reduction in phosphorus concentration from river inputs to control phytoplankton biomass. Despite this ongoing management, the state of the phytoplankton population within the lake in relation to water quality has not been analysed in depth since its formation. This study undertook an extensive assessment of the hydrological, chemical and biological variables in the lake to determine the controls on the phytoplankton community,and the implications it hasfor water quality managementof the system. Cardiff Bay is a unique site that acts more like a river system than a lake. Its’ polymictic nature prevents the lake from stratifying, and its low phytoplankton biomass is controlled by fast flushing rates and filter-feeding by zebra mussels. The lake supports a healthy phytoplankton population that is not nutrient limited and does not contribute to dissolved oxygen concentrations. This study has highlighted the unique relationships that take place within Cardiff Bay, and the need for an advanced understanding stemming from this research to ensure that management can take place to successfully maintain the clear water state of the lake, under the stressors of changes in climate.

Earth’s landmark greenhouse-icehouse transition at the Eocene Oligocene Transition (EOT) is arguably one of the most important climatic events in geological history. The dominant global geochemical signature of this dramatic shift in Earth’s climate (approximately 33.7 million years ago), a 1.2 - 1.5%o increase in the stable oxygen isotope ratio (d18O) of benthic foraminifera, represents a significant period of global cooling that occurred contemporaneously with the initiation of widespread Antarctic glaciation. The EOT represents the first establishment of a widespread, continental-scale, somewhat stable ice sheet on Antarctica and yet significant debate remains as to the forcing mechanism responsible for this substantial perturbation marking the end of the Eocene greenhouse world. Initiation of the step-wise shift in d18O occurred during an interval of low eccentricity and low-amplitude change in obliquity; an orbital configuration considered the ultimate trigger for glaciation at the EOT and the pacemaker for subsequent ice sheet growth. However, some other forcing mechanism(s) must have been important in conditioning the climate leading up to the EOT as these orbital configurations are found at other points in geological history where such large-scale changes in climate are absent. The overall aim of this thesis is to explore the evolution of temperature, ice volume and ocean circulation, the interactions between these key climatic parameters and the relative importance of different forcing and feedback mechanisms across the EOT. This thesis will place particular emphasis on paleoceanographic changes that occurred in the Atlantic Ocean region across this interval and their subsequent impacts. To this end, multiple records of foraminiferal stable isotopes and trace elements, and fish teeth neodymium isotopes are presented from sediment cores largely within the Atlantic Ocean or subject to its influence at the EOT. Findings of this thesis suggest a fascinating link between deep water formation in the North Atlantic Ocean and Antarctic ice sheet dynamics at the EOT. A new highresolution eNd record derived from fossil fish teeth at ODP Site 1263 (Walvis Ridge) in the South Atlantic provides evidence for a significant strengthening of Northern Component Water (NCW), a paleo pre-cursor to North Atlantic Deep Water (NADW), at 34.7 Ma one million years prior to the onset of the EOT. The increasing influence of northern-sourced deep waters, and associated cross-hemisphere heat piracy, provided optimal conditions for landmark climate change prior to the occurrence of the orbital parameters considered to be the ultimate trigger of the EOT. From this point on, NCW played a significant role in the distribution of heat and salinity within the Atlantic Ocean basin and is likely partly responsible, along with enhanced production of Antarctic Bottom Water (AABW) due to Antarctic glaciation, for the interhemispheric temperature asymmetry documented within this thesis. Benthic foraminiferal Mg/Ca-derived bottom water temperatures from IODP Site U1406 (Newfoundland Sediment Drifts) in the North Atlantic show a much lesser degree of cooling in the high northern latitudes when compared to their southern counterparts; in line with previous evidence from records of sea surface temperature (SST). Benthic foraminiferal trace element data from IODP Site U1406, along with ODP Site 925 (Ceara Rise) in the Equatorial Atlantic, demonstrate a regional, transient excursion in primary productivity that begins coeval with Antarctic glaciation at the EOT. Arctic Ocean continental shelves served as a nutrient-rich source fuelling the III Cardiff University Amy Sparkes productivity pulse in the Atlantic at the EOT when glaciation-induced sea level fall exposed organic-rich shelf sediment nutrients to weathering. This new source of bioavailable nutrients was efficiently distributed through the North Atlantic region by surface water overflows between the Greenland and Norwegian Seas and the North Atlantic causing increased primary productivity and associated export production leading to a steepening of the overall decline in pCO2 and hence acting as a positive feedback on Antarctic Ice Sheet (AIS) growth. Overall this thesis makes significant strides in clarifying the timeline of key climatic events in the Atlantic Ocean in the lead up to and across the EOT and highlights the importance of the influence of the Arctic Ocean and North Atlantic in modulating climate and ocean chemistry at the EOT.

Boron doped diamond (BDD) has found numerous applications for electroanalysis in recent years. It’s material properties set it apart from other electrode materials due to its oft quoted wide solvent window and low background capacitances. However, the electrochemical performance has been shown to be highly dependent on the quality of the material, in particular it’s sp2 carbon content. For some applications, such as pH sensing, it has been shown that the inclusion of sp2 carbon impurities is advantageous. This can be achieved during diamond growth or by post-processing procedures, such as laser micromachining, as has been used in this thesis. Herein methods for electrochemically measuring surface sp2 carbon have been developed, and the functional groups on the electrode surface used for pH sensing applications and the underlying sp2 carbon component for dissolved oxygen sensing via the oxygen reduction reaction. To develop a pH sensor that works in unbuffered solutions laser micromachining, with control of the quinone surface coverage, was combined with pulsed voltammetric techniques to avoid perturbing the interfacial environment and control the local pH change. To further enhance pulsed voltammetric techniques, as used throughout this thesis, the raw current-time data was captured and post processed to extract information on the non-faradaic processes occurring, in addition to optimising the faradaic response. This work together advances the understanding of the effect of sp2 carbon in BDD electrodes and its use for electrochemical applications that requires optimisation of the material properties and electrochemical methods.

Satellite data have fundamentally changed how we perceive and understand the world we live in. The amount of data produced is rapidly increasing and classical computing resources and processing tools are no longer sufficient. These massive amounts of data require huge storage in addition to advanced computing capacity in order to allow users to benefit from the derived datasets. Cloud computing has provided the required storage and computing capacity on a scalable level to add or remove resources according to requirements. Simultaneously, recent advances in data processing techniques such as Deep Learning (DL) have paved the way to integrated solutions for Earth Observation (EO) big data understanding. By bringing together a unique combination of computing capacity, ultra fast data storage and advanced data processing techniques, our ability to derive useful insights will be revolutionised. This thesis focuses on harnessing cloud computing and deep learning capabilities to enhance spatial resolution of satellite imagery data. Particularly, the thesis highlights cloud computing architectures to accommodate satellite image processing services. A conceptual data model was developed to enable utilising cloud computing resources with EO big data in near real-time. Moreover, a state-of-the-art super resolution algorithm (SRCNN) was adapted and tested in detail to be exploited with the satellite image domain. In addition, a novel fusion-based data augmentation approach was developed to boost super resolution accuracy. To evaluate the super resolution accuracy with a real-life application, landcover classification was adopted to assess the accuracy between super resolved Landsat-8 data and crowd-source data collected using the Google Earth interface. The accuracy achieved opens a wide field of research with deep learning and data augmentation in the satellite image super resolution domain.

Igneous sill intrusion majorly impacts sedimentary basins, causing forced folding of host rocks, thermal maturation of source rocks, and basinal fluid flow changes. However, the detail of these effects has received little study. Similarly, the mechanisms by which sills are emplaced in basins are poorly understood, and emplacement mechanism may influence the aforementioned basinal impacts. The key that ties impacts and mechanisms together is that models explaining both have not been tested due to a lack of data on sill dimensions. Seismic reflection data presents a unique opportunity to collect detailed measurements on sill dimensions. Work presented in this thesis suggests that the number, shape and dimensions of sills have significant differences between sedimentary basins, having major implications for palaeoclimate modelling. Comparing theoretical sill models with measurements of actual sills undermines many models based around linear elastic fracture mechanics. However, intrusion models which incorporate an overlying elastic plate predict far more accurate sill geometries in comparison with seismic measurements. Additionally, several authors have noted that there is a discrepancy between the amplitude of forced folds and the thickness of their underlying sills. This thesis shows that a large proportion of this discrepancy can be explained by compaction of the fold after sill emplacement. While collecting data on forced folds, a seismic reflector in the Northeast Rockall Trough was mapped which displays undulose topography. Multiple observations point to this reflector being an opal A - opal CT transition. Numerical modelling and kinetic parameterization of the opal A-CT indicates that this topography can arise from local lateral temperature variations. Finally, a recently published model for hydrocarbon prospectivity based on fluid flow arising from sill tips is investigated. It is demonstrated that the original study shows no evidence for the validity of the model, prompting new questions on the scale at which intrusions could affect fluid flow. This thesis therefore shows that current paradigms of sill intrusion mechanisms, palaeoclimate model parameterizations, opal A-CT formation mechanisms and intrusion related fluid flow all need to be reexamined.

Loosely packed sandy soil, created via aeolian deposition and stabilised by interparticle bonding via gypsum crystals (dispersed within the soil fabric), are a significant geohazard in hot, arid environments such as the Middle East (for example, these deposits cover a large area of Iraq). Gypsum, being a moderately soluble salt, can have a substantial influence on the engineering properties of soils, and changes in water content can result in rapid collapse of the soil fabric, damaging surrounding structures; i.e. these deposits are metastable. A search of the literature illustrated that no research focused on the behaviour of an aeolian gypseous soil in environmental conditions. Also, employing electrical resistivity, which might be a helpful tool to monitor water movement in the soil deposit, has not been considered previously. This study, therefore, examined two interconnected experiments. The first aimed to study the impact of groundwater movement (the dimensions of the samples were 144 mm diameter and 300 mm height, with 10% and 20% gypsum content) due to evaporation through an unsaturated column of gypseous soil. These samples were exposed to various conditions, including changing gypsum content, groundwater, temperature gradients, and a breeze across the upper surface of the samples. The second study aimed to determine the stress-settlement characteristics of a pad footing resting on gypseous soil deposit (the dimensions of the samples were 349 mm diameter and 300 mm height, with 20% gypsum content) when exposed to groundwater flow, with and without exposure to the environmental conditions used in the previous study (temperature gradient, and breeze). Electrical resistivity was used to monitor the movement of salty water through the samples in 'quasi-real-time', without having to dissect the samples. Obtaining undisturbed samples of this soil to study in the laboratory can be problematic for logistical reasons. Therefore, a method has been developed that produces repeatable samples with the desired properties to facilitate a systematic investigation of these soils without the need for sampling. This method offers flexibility so that large and small samples can be created for investigation. Samples with a range of gypsum content (from 5% to 30%) were investigated with an oedometer and with unconfined compressive strength apparatus, and it is clear that increasing the gypsum content results in stronger material that exhibits greater iii collapse potential when inundated with water. Secondary compression and creep appear to be important mechanisms when considering settlements with inundation of water, suggesting that longer duration load steps should be used in compression tests (90 days were used herein) than the normal 24-hour period if the metastable nature of these materials is not to be underestimated. It is apparent from the evaporation test that, over time, manufactured soil experiences partial dissolution and re-precipitation of its gypsum, with precipitation taking place in the upper layers of the soil as the water evaporates from the soil under increasing temperatures. While the dissolution of gypsum does not appear to be the dominant mechanism dictating the metastable response of the soil samples in the three footing tests, where partial dissipation of suction and possible softening of cementitious bonds via the gypsum crystals, appears to have a more pronounced impact due to both the time required for a collapse to occur and the volume of water required to trigger a collapse event. The soil resistivity was very sensitive to moisture, temperature, and load-induced variations rather than crystal gypsum variation. Conditions of stress, temperature, and moisture substantially affected the current passing through the soil fabric. It was found that increasing the gypsum content provides more ions for electrical conduction, leading to an increase in the pore water conductivity and therefore diminishing soil resistivity. However, the soil resistivity for the three footing tests was completely different upon failure, and this due to the test conditions (amount of water, densification of the upper layer, temperature, and test time).

Future robotic exploration missions within the Solar System, focussing on either scientific discovery or the emerging field of In-Situ Resource Utilisation (ISRU), shall require the development of technologies which are capable of exploring to ever-greater depths beneath the planetary surface. In order to achieve these ambitious goals, advances in the existing state of the art in robotic sampling are required. This Ph.D. presents findings on the development of novel solutions within this field. The development of the Ultrasonic Planetary Core Drill (UPCD), a system based upon the ultrasonic-percussive drill technique, was designed with a Mars Sample Return (MSR) objective at the core of the development. Breakthroughs in autonomous control and the robotic assembly of drill strings were required in order to meet the requirements set. The system was tested at Coal Nunatak, Antarctica, in December 2016. A rotary-percussive drilling system for use in extracting subglacial bedrock samples from Earth's Polar Regions was developed. Making use of technologies devised in the UPCD project, this collaboration with the British Antarctic Survey (BAS) required a low resource approach to the problem in order to ensure compatibility with existing BAS systems and logistical constraints. Building upon technologies developed and confidence generated in previous systems, the subglacial bedrock was industrialised into what became the Percussive Rapid Access Isotope Drill (P-RAID). This system underwent initial field trials at the Skytrain Ice Rise, Antarctica in January 2019 with the intention to further develop the system for full deployment.

Boltysh was of particular interest due to its chronological proximity to the Cretaceous- Palaeogene (K-Pg) boundary, but also due to the silicic melt rock that is known to decrease argon mobility, and therefore make impact melt rocks susceptible to extraneous 40Ar, causing older measured ages and/or discordant age spectra. For the first time, impact melt rocks from the Boltysh impact structure were analysed under the same experimental conditions as sanidine from the K-Pg boundary in Montana (IrZ sanidine), to provide the first high-resolution chronologic comparison of the Boltysh impact event and the K-Pg boundary. Results from Boltysh yielded a refined 40Ar/39Ar age of 65.47 ± 0.21 Ma. This age is three times more precise than the previously accepted 40Ar/39Ar age of 65.80 ± 0.64 Ma. It is also ~0.6 Ma younger than the palynologically derived age that suggested Boltysh predated the K-Pg boundary by 2-5 ka. The new 40Ar/39Ar age of 65.47 ± 0.21 Ma is ii preferred compared to previous ages, as it was reproducible across two samples in this study, is within uncertainty of the previous 40Ar/39Ar age, and is in agreement with the predicted cratering rate of ~1.2 impacts ≥ 20 km in diameter on land every million years. Therefore, the Boltysh impact event occurred 0.573 ± 0.231 Ma after the K-Pg boundary (66.043 ± 0.086 Ma). Chicxulub was an intriguing target for 40Ar/39Ar geochronology due to its temporal association with the K-Pg boundary. Impact melt rocks from the peak-ring, which were recently recovered by IODP-ICDP Expedition 364, were analysed under the same experimental conditions as IrZ sanidine and Chicxulub-related impact melt glass spherules from Beloc, Haiti and Gorgonilla, Colombia. This sample set provides the first high resolution chronologic comparison of material from within the Chicxulub impact structure, associated spherules, and the K-Pg boundary. Step-heating experiments on these samples yielded five age groups: 1) ~66 Ma (K-Pg age), including IrZ sanidine and all impact melt spherules; 2) a spread between ~66 and ~62 Ma; 3) ~62 Ma; 4) ~61 Ma; and 5) ~49 Ma. These age groups are interpreted to represent the impact age (~66 Ma) followed by cooling of the hydrothermal system in at least two stages (~61-62 Ma), and a post-impact thermal event (~49 Ma). The hydrothermal system at Chicxulub therefore lasted approximately 6 Ma, three times longer than previously predicted by models (~2 Ma). The techniques refined in this thesis show that 40Ar/39Ar geochronology is an excellent technique for age determination of terrestrial impact structures, and can be applied with great efficacy even in challenging lithologies. It is therefore of great utility for deconstructing the thermal histories of extraterrestrial samples. Exploring the surfaces of other planets, particularly Earth's Moon and Mars, is a primary goal of space agencies the world over. Increasing our knowledge of hypervelocity impact processes will not only help us to better understand Earth's history, but will prepare us to study samples returned from Mars, Earth's Moon, and asteroids, thereby increasing the scientific return of planetary exploration - which will be one of the most important and rewarding scientific endeavors over the coming decades.

In the search for signs or traces of extraterrestrial life we are confined to our understanding of how life arose on Earth, processes that are intrinsically tied to our understanding of both the biotic and abiotic process that formed many of the features on this planet. Understanding how life arose on Mars, and where any such signs of life could persist, requires an understanding of the same processes that took place on Earth, in addition to how those signs could have persisted over the timescale in which Mars would have been considered a 'lifeless' planet. Exploration of Mars is highly dependent on prioritization of sample sites that maximise the potential for discoveries that justify the expense and difficulty of exploring a planet that is not our own. This study sought to determine whether a possible origin of life environment could provide data sufficient to encourage targeting such a location for future Mars missions. Hydrothermal vents where heated waters from a volcanically active zone could provide the necessary mineral surfaces, thermal gradient and possible sources of organic molecules from the earth's crust to form the first proto-cells. Both terrestrial and particularly aquatic hydrothermal vents are the source of energy for many bacteria. In aquatic settings a hydrothermal vent is often the sole source of energy for any potential community. The silica sinters analysed in this thesis returned 3 potential sources of biosignatures; actively viable bacteria that were able to be cultured; visual evidence of microbial encrustation in the form of filamentous or coccal bacteria; and organic biomarkers in the form of n-alkanes, fatty acids and other organic compounds. It was also established that the Chilean Altiplano could be considered a Martian analogue due to its similar environmental characteristics (temperature, humidity, increased UV, low biomass) and a diurnal soil cycle matching that on Mars with regards to cold atmospheric temperatures and surface heating of soils leading to a fluctuating temperature and soil humidity profile.

This work discusses the dynamic development of hydraulic fractures, their evolution and the resulting seismicity during fluid injection in a coupled numerical model. The model describes coupling between a solid that can fracture dynamically and a compressible fluid that can push back at the rock and open fractures. With a series of numerical simulations it is shown how the fracture pattern and seismicity change depending on changes in depth, injection rate, Young's modulus and breaking strength. Simulations indicate that the Young's modulus has the largest influence on the fracture dynamics and also the related seismicity. Simulations of rocks with a Young's modulus smaller than 10 GPa show dominant mode I failure and a growth of fracture aperture with a decrease in Young's modulus. Simulations of rocks with a Young's modulus higher than 10 GPa show fractures with a constant aperture and fracture growth that is mainly governed by a growth in crack length and an increasing amount of mode II failure. This change in fracture geometry evolution has an effect on the observed seismicity. Rocks with a Young's modulus of 10 GPa have the smallest moment magnitude while both decrease and increase of Young's modulus value contribute to a growth of the seismic moment magnitude. The signal is further altered by non-linear change in dip and tensile angle depending on the Young's modulus value. It is proposed that two distinct failure regimes are observed in the simulations. Below 10 GPa a fracture propagates through growth in aperture, this causes the fracture tip to be under constant extension. For rocks above 10 GPa, the aperture is small and the fracture is under compression. In this case fracture growth is driven by stress intensification at the crack tip, which causes fracture opening to have greater proportion of mode II compared to mode I. To suppliment the observations made from numerical simulations, laboratory experiments with air injection into vertically orientated Hele-Shaw cell were carried out. Strain analysis of the recorded experiments showed stress regimes that are very similar to the ones observed during numerical simulations with soft rocks. In both cases negative strain fields could be observed in front of the fracture tip. This indicates that fracture propagation for soft materials is driven by tensile failure and walls being pushed apart. Further analysis on fracture propagation mechanisms and solid media response were carried out. These results are applicable to the prediction of fracture dynamics and seismicity during fluid injection, especially since we see a transition from one failure regime to another at around 10 GPa, a Young's modulus that lies in the middle of possible values for natural shale rocks.

The search for life beyond Earth, and on Mars in particular, is one of the key points of astrobiology research. However, space missions are expensive and time-consuming. Simulating such missions at analogue sites on Earth can thus save time and money whilst working in natural settings. This thesis presents three studies of biosignatures from three different martian analogues. These biosignatures were linked - when possible - to environmental parameters observed at their sampling sites. The first study was set in a hot a dry environment in the Atacama Desert in Chile. It aimed to identify biolipids and genetic material in soil samples, along a high-resolution shallow depth profile in a dry alluvial fan. Signs of microbial life were observed at the surface, despite the extreme environmental conditions, and at deeper depths - together with degraded plant material - above a layer of very fine grained sands and silts. Overall, biolipids of plant origin showed the strongest concentrations, despite the quasi-absence of plants at the surface. The poor quality of the DNA sequencing results prevented their interpretation. The sedimentation history of the sampling site seemed to be more complex than what could be observed at the surface. The second study was on the flank of the Sairecabur, a high-altitude volcano in Chile. Soil samples, taken along four depth profiles following an altitude gradient, were analysed for their biolipids and genetic material content. Again, biolipids of plant origin showed the strongest concentrations - both at vegetated and barren sites - and the poor quality of the DNA sequencing results prevented their interpretation. Additionally, the variable environmental and physico-chemical conditions at the different sampling sites makes it more challenging to draw conclusions regarding the altitude gradient. The third study took place inside the crater of Hverfjall, a tuff ring volcano in Iceland. Colonisation of the crater by life was studied by measuring microbial activity and biolipids in soil samples along a transect across the crater, and by considering the relationship between the results and the wind patterns over and within the crater. The results indicate that wind may be a major factor for controlling the deposition and removal of biosignatures in Hverfjall's crater. All three sites were isolated environments. Despite this, lipid biomarkers, genetic material or microbial activity were observed at each of these sites. Molecules produced by plants were also found everywhere despite the general absence of nearby plants, implying some external source for the molecules. Aeolian input is probably the dominant factor for spreading biosignatures to these isolated locations. The high altitude sites on the Sairecabur can serve as analogues to for a Noachian Mars, when the planet lost its global habitability, whereas the Atacama desert is an analogue for present-day Mars. Hverfall serves as an analogue for both past and present Mars, focusing on wind dispersal of biomarkers. The results obtained suggest that if any active biomarker source (i. e. life) were to be identified on Mars, downwind sampling represents an alternative means by which to sample biomarkers whilst avoiding any direct contamination of the source.

Effluents produced from the coal conversion industry, particularly from coal gasification, are complex mixtures, rich in semi-volatile organic compounds (SVOCs). In the case of underground coal gasification (UCG), the production of syngas is accompanied by significant amounts of wastewater and tar, the detailed characterisation of which is required for risk assessment and disposal purposes but also for identification of components of high economic value. This characterisation is challenging as these effluents are unique, both in their physico-chemical nature and their SVOC content. Here, a close-to-exhaustive SVOC characterisation of UCG wastewater was performed, with the development of a novel micro-extraction method, which utilises three physico-chemical effects: ultrasonication, emulsification and salting-out. The delivery of ultrasound in the samples was performed using a novel system that transmits ultrasound into a vessel's contents through its wall, and was named high-intensity vessel-wall sonication (HIVS). The developed ultrasound-assisted surfactant-enhanced salting-out emulsification micro-extraction (UASESOEME) method proved to be successful in the extraction of SVOCs from UCG wastewater, overcoming limitations of previous methods. The HIVS technique was also applied in the development of a fast and precise ultrasound-assisted extraction (UAE) method for coal tar and in the development of an ultrasound-assisted derivatisation (UAD) method for derivatising extracts from both wastewater and coal tar, significantly enhancing their gas chromatographic analysis. Analytical methods for gas chromatography coupled to mass spectrometry (GC-MS) and comprehensive gas chromatography coupled to time-of-flight mass spectrometry (GCxGC-TOFMS) were also developed to analyse the extracts. The above methods were applied in the extraction of SVOCs from three time-series of samples (two from simulated ex-situ UCG experiments and another from an in-situ field-scale UCG trial) and in the extraction of a series of leachates from tar leaching experiments performed with tars of increasing weathering/processing. Analyses yielded comprehensive datasets that were processed using a custom data processing approach and analysed using exploratory and multivariate statistical analysis techniques for sample classification and marker discovery. Time-series analysis indicated several SVOCs as markers, mostly oxygen and nitrogen containing compounds, most of which are not commonly considered in gasification studies; the differences between the two matrices was also highlighted, indicating coal tar as the most representative of the two. Analysis of leachates showed that they can be classified based on their SVOC signature according to the parent tar type; also, tars were shown to continue leaching SVOCs after weathering/processing and that their solubility is dependent on the ionic strength of the leaching medium.

When stones are incorporated into buildings their mineralogical composition and texture alters to adapt to the new environmental conditions. One of the most common building stones in Scotland is sandstone. Due to its high porosity and mineralogical composition sandstones can be prone to weathering. Scotland's diverse stone built heritage is endangered by frequent changes in environmental conditions such as cyclic wetting and drying and temperature changes caused by insolation. Buildings also face increased pressure through climate change. In Scotland, the decay of sandstone is a serious problem that urgently requires new approaches to preserve built heritage and to reduce maintenance costs. It is therefore important to understand the extent and timescales of weathering processes. New approaches to assess stone decay are required for deciding on the best conservation strategy for historic buildings. These approaches or tools need to be minimally or non-invasive, portable and provide a consistent method to gain empirical data for evaluation of the progress of weathering. This project aims to develop two new in-situ techniques that can assess the state of decay of building stones beneath their outer surface. The developed techniques use a laser interferometer to measure dilation over time and an ultrasonic drilling tool to estimate the structural properties of the stones. These measurements are joint with micro-climate monitoring of sandstones to enable a combined assessment of stone decay. The laser interferometer can measure decay induced contraction or expansion of stones on the nanometre scale. Salt crystallisation in porous systems can be examined with very high precision under any temperature and humidity condition that enable salt growth. Characterising dilation events through precise measurement of displacement and its frequency can provide insight on the intensity of decay of the building material. The drying behaviour of different samples (unweathered, weathered and artificially weathered) was monitored to enable the differentiation of rock type and state of decay. The ultrasonic drilling tool allows identification of changes in the structure of a sample while drilling a hole up to 4 cm depth. By continuously measuring the power required to drill, porosity changes and/or the presence of salt at depth can be mapped. The use of ultrasonic tools enables penetration of the rock with less average force on the stone and a faster progress rate into hard materials without a significant wear effect on the drill bits. Operational settings can be kept constant for different physical properties of the rocks such as compressive strength. Monitoring of the power consumption enables to determine different stone types and the location of salt accumulation/damage in artificially weathered sandstones. Micro-climate monitoring includes the measurement of temperature and humidity changes at the surface of building stones. The analysis enables an identification of areas that suffer from increased stress caused by frequent and high rates of changes in temperature and humidity. A study at four historic buildings was conducted for nearly two years. The sites include the University of Glasgow, Dunkeld Cathedral, Jedburgh Abbey and Fort Charlotte (Shetland Islands). Seasonal changes, stone type and north-south elongation were evaluated for determining rocks with increased weathering risks. The developed techniques provide a more precise identification of stone weathering and allow for better prediction of the decay processes. The techniques allow up-scaling from the lab to the field, and can potentially be used in-situ on historical buildings under site conditions.

Continental sabkhas are present within many arid sedimentary basins, however they are often overlooked compared to coeval aeolian and fluvial deposits, despite their potential to record and preserve sedimentary signatures relating to basin formation and fill. The relationships between evaporitic sabkha deposits and genetically-related coeval clastic sediments are strongly influenced by complex processes between autocyclic and allocyclic controls, including climate, however within arid continental settings these signatures are often difficult to detect within the preserved sediments. This thesis presents results from the margin of the Cedar Mesa erg of the Paradox Basin, Utah, USA, which preserves complex interactions of clastic and evaporitic sediments. Studies are based upon extensive regional fieldwork examining the sedimentology, geometries, and interactions, complemented with outcrop gamma ray data and microfacies analysis. The sedimentology shows large variations spatially and temporally which grade through aeolian, sabkha and lacustrine settings with complex interactions occurring where these sediments transition. This work details the facies present in a continental sabkha allowing for identification and interpretation of these complex interbedded relationships over a regional scale. The results have been developed into idealised models and recognisable log signatures which characterise and assess their impact on reservoir quality. Cyclic climatic trends, on various orders of magnitude, have been identified in relation to distinct spatial facies changes. Identification of these allows for basin-wide correlation and prediction of where facies will occur in space and time. These results are applied to evolutionary models applicable to subsurface data from the arid Permian basins of the North Sea, in order to better characterise basin-scale migration and reservoir quality in terms of the evolving basin fill.

Geotechnical site investigations are vital for any construction project in brownfield re-development and/or greenfield sites. Many non-invasive, near-surface geophysical techniques are used for site characterisation, with electrical resistivity and seismic methods being two of the most popular techniques. Although electrical resistivity has been used to detect buried foundations in brownfield sites, there is still research needed to identify optimal survey parameters and electrode configurations. In this study, four of the most common resistivity arrays (Wenner, dipole-dipole, pole-dipole and pole-pole) were utilized, on profiles (0.25 m electrode spacing and 64 electrodes) at different orientations and distances from a scaled-model of a buried foundation wall (wall dimensions are 1.5 m long × 0.36 m wide × 0.48 m height). The Wenner and dipole-dipole arrays, with surveys oriented parallel to the foundation wall, were found to be optimal. Integration of geophysical (seismic (using 24 geophones and 1 m geophone spacing), electrical resistivity (2, 3 and 4 m electrode spacing and 64 electrodes) and gravity) with conventional in situ CPT tests surveys allowed good site characterisation of a geologically heterogeneous site. Seismic surveys are routinely conducted for shear wave velocity-depth profile site determinations. Train-induced vibrations have been shown to be used as passive seismic sources for site characterisation studies. In a Midlands glaciated valley site, passing train vibrations were collected using three-component seismic stations and 1D/2D array configurations. Linear arrays (115 m total length and 5 m geophone spacing), oriented parallel to the railway, were found to be optimal. Analysis of three (i.e. vertical and horizontal) components revealed different shear wave velocities; however, it cannot be the case for the same site. Observing apparent wave velocities was the main interpretation for the differences in wave velocity. In addition, time-frequency analysis showed that potential Doppler shift was not noticeable on the observed train-induced vibrations.

The Neogene (c. 23-2.6 Ma) is the most recent period of Earth history in which atmospheric CO2 was last >400 ppm; possibly associated with dramatic fluctuations in Antarctic ice volume and thus eustatic sea level. With continental configurations broadly similar to today, the Neogene therefore provides an opportunity to characterise and explore the different feedbacks and configurations of Earth's climate that occur under climatic forcing conditions either similar to today or to projected anthropogenic warming scenarios. However, many important questions in Neogene paleoclimatology remain unanswered. For example, the role in and response of the Southern Ocean, a key modulator of the Antarctic ice sheet and a disproportionately important player in the carbon cycle, to major episodes of climate change. In this thesis, diatom-based proxies, which tend to be well-preserved in the Southern Ocean, are developed and applied to some of the big questions in Neogene paleoclimatology. Here, high resolution quantitative diatom assemblage records across the Middle Miocene Climate Transition (15-12 Ma) at a latitudinal transect of three Antarctic Zone ODP Sites (747, 744 and 1165), and a record at Site 1165 extending to the present, provide paleoceanographic insights. For example, the expansion of marine ice into Prydz Bay at 13.8 Ma, followed by eccentricity-paced Southern Ocean cooling and intensification of the Antarctic Circumpolar Current (ACC) at c. 13 Ma. Further cooling and full expression of the ACC during the Late Miocene was interspersed with transient warm intervals, possibly associated with ice sheet retreat. Unique Early Pliocene paleoceanography is indicated by diatom assemblages at high latitude circum-Antarctic sites, including Site 1165, dominated by Thalassiothrix, Thalassionema and Trichotoxon diatoms. These assemblages suggest substantially increased high latitude oceanic upwelling, which could have provided a source of heat contributing to Pliocene ice sheet retreat. Finally, the first Pliocene Southern Ocean diatom silica stable oxygen isotope record (δ18Odiatom) at Site 1165 (3.45-3.75 Ma) explores the application of this proxy to Neogene material, alongside a geochemical assessment of sample purity. A strong correlation between Al/Si and δ18Odiatom (r = -0.89, p = < 0.01, n=46) suggests clay mineral-mediated secondary isotope exchange has overprinted the environmental signature at Site 1165 which, in the context of published and unpublished data, may be either age- or site-dependant. Any future study using δ18Odiatom, particularly within Neogene material, must therefore include a geochemical assessment of sample purity and carefully consider the correlation between δ18Odiatom and Al/Si before interpreting δ18Odiatom as a paleoenvironmental signal.

The Central Arran Igneous Complex - a system of intrusive and pyroclastic volcanic rocks - is one of the least understood onshore 'central complexes' of the British Palaeogene Igneous Province (BPIP). The BPIP is part of the wider North Atlantic Igneous Province, formed during opening of the North Atlantic Ocean and the arrival of the Iceland plume at the base of the lithosphere. Despite being known about for over a century, the magmatic and volcanic processes that formed the Central Arran Igneous Complex remain poorly understood. The Central Arran Igneous Complex comprises a number of granitic and dioritic intrusions, a caldera-fill succession of pyroclastic and sedimentary rocks intruded by a dolerite sill, and a series of dykes ranging in composition from picrite to pitchstone. This study uses a combination of field mapping, whole-rock elemental geochemistry, radiogenic isotope geochemistry, and U-Pb zircon geochronology to determine how these units and their magmas formed, how they relate to one another, and their relationship with other igneous rocks throughout the BPIP. Detailed study of the intra-caldera stratigraphy allows a prolonged volcanic history to be pieced together, with pyroclastic units separated by erosional surfaces indicating periods of volcanic quiescence and sedimentary processes. Following the initial period of caldera collapse, which was accompanied by highly explosive eruptions, volcanism was generally less explosive and formed abundant high-grade and lava-like ignimbrites. The majority of magmas were derived from a mantle source compositionally transitional between N-MORB and the Iceland plume. Geochemical differences between the mafic units are derived from different degrees of melting, from different source regions. All magmas show some degree of crustal contamination by various units, and their isotope geochemistry can be used to constrain the poorly understood crustal architecture in the region. U-Pb zircon geochronology shows that magmatism in central Arran took place over a very short space of time. The difference in interpreted 206Pb/238U ages between the oldest (Allt Ruadh Member ignimbrites; 58.92 ± 0.19 Ma) and the youngest (granitic Glenloig Hybrids; 58.71 ± 0.07 Ma) dated units is ≤ 470 kyr.

Tellurium (Te) and Selenium (Se) are identified as elements critical to the European Union's Strategic Energy Plan: both essential components in the manufacture of thin-film photovoltaic solar cells. Their strategic importance is however paralleled by a poor understanding of their distribution and enrichment in a range of ore-forming environments. The significance of Te and Se in green energy production, their rapidly increasing demand and by-product nature of supply has led to their classification as critical elements by the EU and rest of the world. To address concerns over the supply of Te and Se, the UK National Environmental Research Council established the SoS Minerals (Security of Supply) initiative, within which the 'TeaSe' consortium aimed to characterise Te and Se in a range of ore-forming environments. This current study, which forms part of the larger TeaSe project, focuses on the distribution and enrichment of Te and Se and associated elements in mafic, Cyprus-type or Cu-Zn Volcanogenic Massive Sulfide (VMS) deposits in one of their principal on-land analogues; the Troodos ophiolite of Cyprus. Exceptional exposure, preservation of original seafloor spreading structures and the lack of any apparent metamorphic overprint in this Late Cretaceous (92 Ma) fragment of Tethyan spreading ridge make the Troodos ophiolite the ideal natural laboratory to investigate processes associated with mafic VMS deposits. VMS deposits occur within the extrusive sequence of the Troodos ophiolite, at the periphery of the complex, within a suite of basaltic to andesitic lavas that once formed the palaeo-seafloor. In this study new geochemical, isotopic and mineralogical data from more than 25 VMS and other mineralised localities spanning the entire Troodos ophiolite is presented, thereby ensuring a representative range of ore-forming processes that control the distribution of Te and Se in Troodos VMS deposits are characterised. Because of a lack of historic data the concentration of Te and Se in mafic VMS deposits has never previously been characterised. This is especially true in the case of Troodos VMS deposits. This study finds that both Te and Se are enriched in Troodos VMS to levels comparable to actively-forming back-arc and intra-oceanic arc-related hydrothermal systems. Furthermore, data highlights the highest Se concentration in pyrite (9565 ppm; n=1514) yet recorded in any VMS deposit regardless of tectonic environment. Additionally, the mineral-scale distribution of Te and Se between different sulfide minerals is not uniform: Se preferentially partitions into chalcopyrite (n=195) whilst Te partitions into pyrite (n=1514). Selenium is most likely incorporated in pyrite and chalcopyrite in a lattice bound substitution whilst Te can occur as either nano to micro-scale inclusions or as a lattice bound substitution. A correlation between Bi and Te in some Troodos VMS (e.g. the Skouriotissa deposit: R2=0.35) suggests Bi-Te inclusions may host appreciable Te. On a deposit scale, localised seafloor oxidisation leads to the extreme enrichment of Se. In the Apliki VMS deposit, a hematite-pyrite-chalcopyrite-rich zone termed the South Apliki Breccia Zone (SABZ) was identified via regional geochemical screening as containing high Se (>1000 ppm). The paragenesis of sulfides and oxides in the SABZ suggest the remobilisation of Se during hematite formation and its incorporation in late-stage euhedral pyrite. This demonstrates the significance of fluctuating redox in leading to the extreme, albeit localised, enrichment of Se. Furthermore, whole-rock geochemical data shows that Te and Se may be enriched through supergene oxidation-related processes, leading to the concentration of Te and Se in Fe (oxy)hydroxide crusts. The distribution of Te and Se between individual VMS deposits on a regional scale (10's of km) across the Troodos ophiolite is extremely variable. Selenium/sulfur ratio, magmatophile trace-element signature and sulfur isotopes have been used to assess variation in magmatic volatile influx and source-rock composition between different VMS deposits. Two processes are proposed that explain the observed distribution of metals and sulfur isotope values in Troodos VMS: i) The leaching of igneous lithologies; or ii) a magmatic volatile influx. The VMS deposits of the Troodos ophiolite occur at different stratigraphic levels within the extrusive sequence: either within the Lower Pillow Lava (LPL), or overlying the Upper Pilllow Lava (UPL). Lava geochemistry between the 'UPL' and 'LPL' is markedly different with the UPL distinctly more primitive in composition, and enriched in Cu+Se+Au relative to the LPL suite. Therefore, assuming that the leaching of igneous lithologies provided the only source of metal in the VMS hydrothermal system, those VMS that postdate the accretion of the UPL can be expected to show an enrichment in Cu+Se+Au (e.g., Skouriotissa, Phoucasa) relative to those that predate them (e.g. Agrokipia). However, some LPL hosted VMS deposits exhibit an unusual enrichment in Cu, Se and Au (e.g. Mala); this could indicate the addition of a magmatic volatile phase. Sulfur isotope (δ34S) measurements of hydrothermal sulfides indicate that the majority of sulfur in the hydrothermal system for a 'typical' Troodos VMS is sourced through the thermochemical reduction of seawater sulfate and the leaching of primary igneous lithologies and formation of epidosites in the sheeted dykes underlying the VMS deposits. Consequently, δ34S values for all Troodos sulfides average +4.7‰ (n=180). However, this study identifies, for the first time, an immature magmatic-dominated sulfur isotope signature in an ancient VMS deposit: the exceptionally preserved Mala VMS. This deposit exhibits a light sulfur isotope signature in pyrite averaging -3.4‰ (n=7), a value significantly less that the Troodos magmatic mean (< 0-1‰). Considered together with its stratigraphic position, deep within the LPL, geochemical and isotopic data suggest that Mala was preserved - probably through rapid burial by subsequent lava flows - during the immature stages of sulfide accumulation, and therefore retains a distinct magmatic volatile-dominated signature that would normally be overprinted and modified during VMS maturation and off axis fluid flow. Evidence strongly suggests that metals in immature VMS deposits, even in the relatively volatile-poor mafic VMS system, are sourced from a magmatic volatile phase during the initial stage of VMS formation. Immature or magmatic end-member VMS deposits (e.g. Mala) are characterised by fluids that probably underwent SO2 disproportionation (leading to δ34S values of < 0‰ in sulfides), an enrichment in magmatophile elements, and apparent lack of zone-refining in the VMS mound. Consequently, Immature VMS deposits exhibit an enrichment in Te, Se and Au, demonstrating a robust link between magmatic volatile influx and the enrichment of Te and Se. In contrast, a 'typical' Troodos VMS deposit exhibits a δ34S signature that is consistent with sulfur derived from the leaching of primary igneous lithologies and the thermochemical reduction of seawater sulfate (δ34S +4.7‰, n=180). The preservation of an immature magmatic signature has only previously been observed in actively forming seafloor massive sulfide deposits in arc-related environments.

This thesis uses the high-quality Poseidon 3D seismic volume, 2D seismic data and well data from the Browse Basin, offshore Northwest Australia. It investigates the initiation, growth and demise of the Miocene Oliver Limestone Formation to understand the relative importance of different exogenic and endogenic controls on carbonate growth patterns. This thesis then goes on to assess the impact of scale relationships, associated with different datasets, on the characterisation of carbonate reservoirs. This is achieved through qualitative and quantitative interpretation of seismic data, outcrop and numerical models. The initiation of a carbonate system within the Browse Basin was first investigated to propose a new evolutionary model for Northwest Australia and to assess the relative significance of fluid flow and fault topography to carbonate build-up development. Faults and fluid flow features were analysed using detailed qualitative and quantitative seismic interpretation. The results demonstrate a positive correlation between fluid flow and the generation of pinnacle features on the Miocene sea floor of the Browse Basin. These pinnacle features are explained in this thesis as the first patch reefs formed in association with mud volcanoes or methanogenic carbonates. They are considered as key features precluding the growth of the larger isolated carbonate buildups. This thesis postulates that pinnacle features above fluid-flow conduits demonstrate a valid seep-reef relationship and are refined diagnostic features for understanding fluid flow through geological time. The geometric and depositional responses of isolated carbonate build-ups to Miocene sea-level change and regional tectonics, was investigated to derive their relative significance on growth patterns and carbonate facies distribution. Seismic stratigraphy and facies associations were interpreted using 3D seismic and borehole data from the Browse Basin, Northwest Australia, combined with outcrop information from the Cariatiz Reef in Southeast Spain. Results documented Messinian structural partitioning to occur across the Browse Basin, with deformation associated with plate collision focused on preferentially oriented faults, i.e. only influencing carbonate buildup evolution at a local scale. Seismic attribute analyses proved highly effective in interpreting carbonate facies, but when compared with outcrop information from Southeast Spain, this same attribute data was limited to features larger than 17 m vertically and 50 m horizontally. Thus, estimations of reservoir potential are significantly underestimated when only based on the interpretation of seismic data. The final part of this thesis investigates the demise of carbonate build-ups in the Browse Basin so as to determine the relative significance of endogenic and exogenic processes in drowning carbonate factories. Growth patterns and drift deposits where interpreted using the high-resolution Poseidon 3D seismic survey and additional 2D seismic lines. The relative significance of different geological processes was investigated using numerical stratigraphic forward modelling (CarboCAT) to test different scenarios based on seismic interpretation and current literature. Results showed that the subsidence rates currently proposed in the literature generated accommodation space in the Browse Basin, but were of insufficient magnitude to drown the carbonate factories. Eustatic sea level did not influence large-scale growth patterns or drowned the build-ups. Hence, this thesis postulates that current activity (with associated deposition of sediment drifts) and excess nutrient supply were key to the drowning of carbonate build-ups in the Browse Basin. These two processes are often overlooked when interpreting the demise of carbonate build-ups on equatorial margins around the world. The overall implications of this work are as follows: 1) Fluid flow should be considered as an important endogenic control on carbonate build-up initiation and therefore the presence of carbonate build-ups in areas of hydrocarbon generation may act as an indicator of seal leakage; 2) Structural partitioning within the Browse Basin had a significant impact on carbonate growth patterns. Thus it is important to consider that localised tectonics can induce significant variability in growth patterns and, therefore, reservoir distribution within a basin; 3) Seismic attributes are a key tool in aiding the delineation of reservoir facies and processes generating secondary porosity (e.g. karsts). As such, they can aid the generation of increasingly robust geological models and thus reduce exploration uncertainty; 4) The primary cause of carbonate build-up demise during the Late Miocene is environmental deterioration as opposed to tectonic or eustatic sea level; 5) Numerical modelling (CarboCAT) proved an effective tool in testing qualitative interpretations derived from seismic interpretation. The numerical modelling completed in this work showed value in predicting reservoir distribution and carbonate growth patterns, parameters that can guide exploration on a basin scale, as well as aid interpretation at an inter-well scale to reduce exploration risk.

The formation of the Platreef in the northern limb of the Bushveld Complex remains unresolved, as does the stratigraphic correlation of the northern limb to that in the wider Bushveld Complex. This is largely due to intense contamination by country rocks modifying the stratigraphy. However, the Flatreef, located down-dip of the Platreef, is relatively less contaminated and offers an opportunity to evaluate the potential correlation between the different limbs of the Bushveld Complex. The present study, focussing on 2 drill cores intersecting the Flatreef (UMT081 and UMT094), has utilised geochemical, isotopic and geochronological data to characterise the Flatreef. Modelling the Flatreef using Mg-Nd-O isotopes indicates that the lower portions of the Flatreef in particular have been affected by contamination. The upper portions have been much less affected, showing important lithological and compositional similarities to the UCZ of the WBC. The present study has also provided the first high-precision U-Pb single-zircon geochronology data for the Flatreef, with ages of purported Merensky Reef overlapping with those of the WBC. In addition, the geochronological data show that the Bastard and UG2 reefs are younger than their hangingwall rocks, supporting a model of out-of-sequence sill emplacement in the Flatreef. The origin of PGE mineralization in the Flatreef remains less clear. Well mineralized sills such as the Bastard Reef imply sulphides were entrained in magmas prior to emplacement. However, elevated grade where the northern limb intrudes dolomitic floor rocks suggests contamination by calcareous sediments and mineralization are linked. In addition, it is likely that the assimilation of calcareous sediments by Flatreef magmas in addition to devolatization of calcareous sediments and dolomites in the wider metamorphic aureole of the Bushveld Complex released significant volumes of CO2 into the Precambrian atmosphere and potentially played a role in the global Shunga Event, whose age coincides with that of the Bushveld Complex.

The global mid-ocean ridge system is the site of 75% of Earth's volcanism. Whilst mid-ocean ridges have been studied for decades, ultraslow-spreading ridges, such as the Gakkel Ridge have received comparably little attention. These ultraslow-spreading ridges are important because, in addition to representing a spreading ridge end-member, they are also volumetrically significant and make up ~36% of the global mid-ocean ridge system. Despite this, we have very few constraints on the physical nature of the underlying magma plumbing systems or the magmatic processes occurring within them. To address this knowledge gap, this thesis presents the first systematic and quantitative analysis of crystal cargo textures and compositions of ultraslow-spreading mid-ocean ridge basalt (Gakkel Ridge, Arctic Ocean). These data are used to infer the physiochemical conditions present within the Gakkel Ridge magma plumbing system. Using the textures and compositions of >1800 plagioclase crystals, the Gakkel Ridge crystal cargo is shown to be complex, with both individual plagioclase and glomerocrysts showing large variations in crystal habit, zoning and resorption. These textures, combined with basalt modal crystal contents, indicate that the crystal cargo is not generally phenocrystic in origin, and that undercooling, magma mixing, decompression and mush disaggregation are important processes occurring within the magma plumbing system. To constrain the depths of crystallisation within the Gakkel Ridge magma plumbing system, volatile contents of olivine- and plagioclase-hosted melt inclusions have been determined. The volatile contents of plagioclase-hosted melt inclusions correspond to significantly higher crystallisation pressures (mean 270 MPa) than olivine-hosted melt inclusions (mean 145 MPa). The higher pressures recorded in plagioclase-hosted inclusions, which correspond to crystallisation as deep as 16.4 km below the seafloor, are consistent with both the proposed thickness of the Gakkel Ridge lithosphere and pressures reconstructed from glass compositions. Contrary to previous studies using olivine-hosted melt inclusions alone, these results demonstrate that mid-ocean ridge volcanoes, at least at ultraslow-spreading ridges, have magmatic roots deep in the lithospheric mantle. The observed dichotomy in pressure recorded in olivine vs. plagioclase indicates that a multi-mineral melt inclusion approach is required to constrain the full range of crystallisation depths present in magmatic systems. Examination of along axis changes in mineral textures, mineral and melt geochemistry, melt inclusion crystallisation pressures, crystal content and ridge bathymetry demonstrates that the nature of the plumbing system and processes occurring within it are variable. There are no systematic changes with decreasing spreading rate along-axis. Instead, variations in the extent of partial melting and the degree of melt focussing along the base of the lithosphere play a key role in influencing the nature of magma plumbing systems at the Gakkel Ridge. Taken together, this thesis builds on our growing understanding of the complexity of processes occurring within mid-ocean ridge magmatic systems. It demonstrates that, contrary to the often-held view that mid-ocean ridges are nominally simple and have shallow magma plumbing systems, the observed textural and compositional complexity and crystallisation depths attest to the presence of vertically extensive plumbing systems within which complex magmatic processes occur.

The physical manifestations of plate tectonics on the modern Earth are relatively well-understood, but the nature and timing of its onset remains enigmatic, with the geodynamic regime(s) that operated during the Archaean hotly debated. This absence of a consistent geodynamic framework within which regional-scale observations can be placed limits our understanding of Archaean assemblages and associated mineral deposits. To engage with the Archaean geodynamics discussion, this thesis focuses on ultramafic-mafic complexes in the Lewisian Gneiss Complex (LGC) of the North Atlantic Craton and Johannesburg Dome of the Kaapvaal Craton. Globally, such complexes have been the subject of wide-ranging interpretations that have disparate implications for Archaean geodynamic regimes. Throughout this thesis, it is demonstrated that confidently constraining element mobility is of paramount importance when aiming to constrain the origin of Archaean ultramafic rocks, with a variety of geochemical proxies shown to be susceptible to element mobility. Notably, high field strength element anomalies - a geochemical proxy commonly used to fingerprint subduction-related magmatism - are here shown to be highly susceptible to element mobility, with the role of subduction as an Archaean geodynamic process potentially overestimated as a result. Such mobility can, however, be constrained and a primary geochemistry obtained using the integrated approach utilised here, whereby detailed petrography, bulk-rock geochemistry and mineral chemistry are examined using the context provided by rigorous field geology. Using this approach, the ultramafic-mafic complexes in the LGC are here interpreted as recording two temporally and petrogenetically distinct phases of Archaean magmatism. One group of complexes likely represents an early ultramafic-mafic crust that pre-dates the tonalite-trondhjemite-granodiorite (TTG) magmas, while a second group of complexes are interpreted as representing several layered intrusions that were emplaced into TTG. The ultramafic-mafic complexes in the Johannesburg Dome are considered to represent intrusive and extrusive remnants of an Archaean greenstone belt, contradicting a recently proposed hypothesis whereby the complexes are interpreted as fragments of an Archaean ophiolite. When combined with similar opposition to other proposed Archaean ophiolite occurrences in other cratons, this contradiction is potentially significant to the Archaean geodynamics debate, raising questions as to the validity of a > 3.6 Ga onset for modern-style plate tectonics.

The Gwna Group contains chaotic, disrupted mélange of unknown genetic history. Publications that speculate on Gwna Group formation often cast the mélange in a pivotal role: the regional co-location of blueschist and greenschist with the Gwna Group has inspired hypotheses of tectonic mélange formation during accretionary orogen subduction, yet no specific published studies of the Gwna Group exist. Detailed field study of the Gwna Group has distinguished primary features from those overprinted by later events, over four defined outcrop belts within which combined stratigraphic relationships are determined. The Gwna Group is emphatically redefined as a sedimentary, gravity flow deposit; • Four basal unconformities demonstrate sedimentary superposition. • Pre-Sturtian molar tooth microspar is described in abiotic Neoproterozoic dolo-limestone clasts within the Gwna Group - the first account in Britain. • A regionally ubiquitous, internally conformable coherent sedimentary system of three main lithofacies is interbedded within repeated megacycles. • The sediments record early Palaeozoic passive margin evolution. New U-Pb zircon investigations and meta-analysis of published ages show the Gwna Group began to accumulate near the Gondwanan margin during early Cambrian rifting and crucially demonstrate no genetic relationship with the Penmynydd Zone as Gwna Group deposition followed exhumation of the blueschists at 560 - 550 Ma.

Improving reliability of components operating at high temperature, such as pipelines, boilers and reactors, within a range of industries is of importance in the asset management process. This thesis concerns the development and testing of ultrasound transducers for use at elevated temperatures, up to 500 _C, without the use of active cooling. Ultrasound thickness measurement applications employing these high temperature transducers includes both portable-type non-destructive testing (NDT) inspections and permanent condition monitoring, primarily towards detection of corrosion and erosion. The development and optimisation of an electromagnetic acoustic transducer (EMAT) design which generates and detects bulk radially polarised shear waves utilising a high temperature permanent magnet and a ceramic encapsulated spiral coil is discussed. This design was optimised for use on magnetite coated mild steel samples; it was shown that the magnetostriction mechanism tends to dominate, depending upon sample properties, producing large signals even at elevated temperatures. High temperature laboratory trials (up to 500 oC) demonstrated the non-linear change in signal amplitude with increasing temperature on magnetite coated mild steel samples, attributed to the complex non-linear relationship between magnetostrictive strains and applied external magnetic field. The EMAT provided good signal amplitude, even at relatively large sample-EMAT lift-off (up to 8.0 mm), demonstrating the applicability of this EMAT for high temperature scanning inspections. A longterm industrial field trial on a high temperature pipeline (≈ 350 oC) in a refinery exhibited the suitability of this design for high temperature continuous monitoring applications. A piezoelectric transducer with a novel compression-type design was optimised for application at high temperature, with the use of a waveguide, high temperature piezoelectric element and high temperature backing material; the optimisation of these components is discussed. This transducer design incorporates compression applied via a central bolt, to achieve acoustic coupling between the components, avoiding the use of adhesive layers, to generate bulk longitudinal waves. With the application of a bismuth titanate piezoelectric element, the transducer was able to generate signals on stainless steel whilst withstanding high temperatures (up to 500 oC) continuously without cooling.

Northern Ireland Waterloo Mudstone Formation has received relatively little attention due to the scarcity of exposures and poor availability of subsurface records. The recent recovery of latest Triassic to Early Jurassic strata from boreholes permits further study of biostratigraphical and palaeoenvironmental using foraminifera and ostracods. The samples are from boreholes (Ballinlea-1, Magilligan and Carnduff-1) and exposures (White Park Bay, Tircrevan Burn, Larne, Ballygalley, Ballintoy and Kinbane Head). The age of the sections, established using foraminiferal biozonation ranges from latest Triassic (Rhaetian) to earliest Pliensbachian (JF9a). The assemblages recovered broadly similar to those elsewhere in NW Europe; European Boreal Atlantic Realm. The latest Rhaetian to earliest Sinemurian low diverse microfossil assemblages dominant by metacopid ostracods with occasional influx of opportunist foraminifera but gradually, foraminiferal abundances exceed the ostracods in the Early Sinemurian onwards with their highest diversity in the Late Sinemurian. The foraminiferal assemblages are dominated by foraminifera of the Lagenida, other groups include the Miliolida, Buliminida and Robertinida. Based on the microfossils, the sediments are considered to represent confined inner shelf environment in latest Rhaetian to Hettangian then gradually recovered to well-oxgenated, open marine deposits of outermost inner shelf to middle shelf in Early Sinemurian to Early Pliensbachian.

Reactive groundwater contaminant transport is dependent upon hydraulic and geochemical property distributions. The aim of this research was to determine, for an example fluvial sandstone: (i) the degree of correlation between geochemical property values and lithofacies (LFs); and (ii) the effect of the correlations on reactive solute transport. A 60 m core from the carbonate-cemented, red-bed Triassic Sherwood Sandstone Group was examined. Five fluvial LFs were identified, in fining upwards cycles from a channel lag sandstone (LF5) to a low energy mudstone (LF1). The main geochemical properties investigated were carbonate content, oxide content, sorption capacity, cation exchange capacity (CEC) and selectivity coefficient; Surface area and colour were also studied. There is a clear distinction in carbonate content, CEC, selectivity coefficient and Fe and Mn oxide content between LF1 and LF2, the ‘mud’ LFs, and the matrix of LF3, LF4 and LF5, the ‘sand’ LFs. In addition, the pellets change the bulk geochemical properties of the sand LF units. Modelling indicated that the pellets can affect solute mobility significantly. Selectivity coefficients show a possible depth zoning. Distribution parameter values obtained characterize the sequence for geochemical modelling and uncertainty estimation. Oxide coating thickness was estimated at about 100nm. CEC was found to be well-correlated with surface area. Colour/Fe/Mn content correlations suggest a possibility in future to use colour logging to indicate oxide content and possibly even surface area and CEC. As the sequence examined appears typical of many red-bed fluvial sequences, it is suggested that the findings may also be typical of other similar continental sandstones.

Evidence exists for great volumes of water on early Mars. Liquid surface water requires a much denser atmosphere than modern Mars possesses, probably predominantly composed of CO2. Such significant volumes of CO2 and water in the presence of basalt should have produced vast concentrations of carbonate minerals, yet little carbonate has been discovered thus far. These ‘missing carbonates’ comprise the Mars carbonate conundrum. This thesis provides insight to the conundrum via three distinct lines of investigation. Firstly, using engineering to expand our ability to locate carbonates on the Martian surface. A Micro-Optic UltraSonic Exfoliator (MOUSE) was designed and built that was tested on a range of rock types and wavelengths. Using ultrasonics demonstrates many advantages over the rock abrasion tool currently used on Mars rovers, including a smoother grind finish and a lower rate of tool tip wear when using tungsten carbide. Secondly, carbonates present in our only samples of the Martian regolith on Earth, meteorites, were studied. Carbonates found in Martian meteorites can provide a record of aqueous and atmospheric conditions extending back over 4.5 billion years. This thesis observes carbonates in two meteorites, ALH 84001 and Lafayette, representing early Mars and more recent Mars respectively, and finds evidence for two types of carbonate replacing glass in ALH 84001. The aqueously altered minerals of these two meteorites were compared with those found in the terrestrial ophiolites of Leka (Norway), and Semail (United Arab Emirates), and these ophiolites were assessed for suitability as Mars analogues. Chemically zoned carbonate rosettes similar to those in ALH 84001 are found in the Semail ophiolite samples. No carbonates were identified in Leka samples, but extensive serpentinisation was present. Finally, this thesis sought to replicate alteration processes and products that are recorded by Martian meteorites within a Mars analogue laboratory environment. The effects of differing initial atmospheric and mineral compositions were explored, specifically the comparison of CO2 and SO2 with basalt versus CO2 with olivine. These three interdisciplinary strands of investigation provide some novel tools, ideas and evidence to help solve the Mars carbonate conundrum.

The uniquely low temperature sensitivity of the apatite (U-Th)/He system makes it an invaluable tool for studying shallow crustal processes which are not accessible through other techniques. Major advancements in both the theoretical and practical aspects of the technique have taken place over the past decade or so, however the routine application of the process is often held back by the perceived problem of single grain age ‘over dispersion’, particularly when applied to old, slowly cooled geological settings. There persists a misconception that age dispersion is indicative of a problem with the apatite (U-Th)/He system. A significant component of single grain age dispersion is inherent to the natural system, and therefore beneficial to reconstructing robust thermal histories. Variations in crystal grain size, accumulated amounts of radiation damage and changes to the helium concentration gradient within a grain due to fragmentation all contribute positively to age dispersion. Other, imposed factors such as crystal zoning and 4He implantation (which are undesirable) can also contribute to dispersion, however in the vast majority of cases their effects are negligible and only contribute noise to the inherent natural dispersion signal. The Ballachulish Igneous complex (BIC) in western Scotland has been used as a case study to demonstrate the range of age dispersion which should be expected when analysing large numbers of single grain aliquots per sample. Where 20+ grains are analysed, total dispersion will often be well in excess of 100% for old, slowly cooled samples, indeed dispersion in excess of 200% is possible. Such dispersion will often be as a consequence of outlying or apparently anomalous ages, however such ages should not be discounted unless there is sound analytical justification to do so. Apparent anomalous ages will often be ‘swallowed up’ by the data if more, or even different sized/shaped grains are analysed. Due to the competing effects of the three main causes of inherent natural dispersion, it should not be expected that large, well dispersed data sets will show any significant correlation between single grain age and either grain size or eU concentration. However a lack of correlation does not indicate poor quality data. Brown, Beucher and co-workers (Brown et al., 2013; Beucher et al., 2013) proposed a new modelling approach to account for the common occurrence of broken crystals in apatite separates, demonstrating that the additional inherent natural age dispersion arising from analysing fragments can be exploited when reconstructing thermal histories. A new inversion technique – HelFRAG was developed, based on a finite length cylinder diffusion model. The model is computationally demanding, therefore sampling based inversion methods requiring many forward model simulations become less practical. Consequently, an approximation of the finite cylinder diffusion model has been incorporated into the modelling software QTQt (Gallagher, 2012). Here, the approximation – QFrag has been demonstrated capable of returning comparable results to the full HelFRAG inversion technique when given the same synthetic data set, enabling the more routine application of the fragment model. Both QFrag and HelFRAG modelling techniques have been used to model the new BIC AHe dataset. The purpose is twofold: to demonstrate the importance of the fragment model with a real dataset, and to provide a new thermochronological interpretation for the BIC. When using this dataset, modelling samples individually shows only subtle differences (if any) between modelling broken grains correctly as fragments, verses modelling them incorrectly as whole grains. A far greater difference in the model output is seen when only modelling 3-6 grains compared to 20+, irrespective of whether fragments are treated correctly or not. When multiple samples are modelled together in a vertical profile, the fragment effect becomes much more important. A very different thermal history interpretation arises when any broken grains are modelled incorrectly as whole grains compared to when modelled as fragments. The new thermal history interpretation for the BIC involves a four stage cooling history from the time of intrusion (c. 424Ma). Very rapid cooling and uplift occurred immediately after intrusion over the first c. 20Myrs of the history (Phase 1). This brought the complex from c. 10km depths to within 2-3km of the surface. There followed much slower continued uplift between c. 404Ma and c. 300Ma, resulting in up to 1km of denudation (Phase 2). Over the next c. 150Myrs only a small volume of uplift occurred, however the geothermal gradient increased towards the end of this time period, suggesting crustal thinning (Phase 3). A final, rapid period of cooling and uplift occurred at c. 140Ma, bringing the top of the profile very near to the surface (Phase 4). No significant denudation has occurred since the end of this rapid uplift phase (10’s to 100’s of meters at most). The first two phases of cooling are interpreted as the final stages of the Caledonian orogeny, with erosion driven isostatic uplift causing continued denudation after the cessation of collisional tectonics. The end of phase three and the subsequent rapid uplift (Phase 4) are interpreted as the beginnings of crustal thinning and continental rifting which ultimately led to the opening of the North Atlantic Ocean.

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 morphologies of pyroclasts in basaltic and silicic ash deposits and tuffs in volcanic sequences have been used by previous authors to determine eruption processes in proximal settings commonly from modern eruption deposits. However, little research has been conducted on the finest tephra fraction, ash and fine-ash, in distal settings. The study of tephra in distal localities, >100 km from source, may provide important information regarding the dispersal of ash from highly explosive large-scale eruptions, for which proximal deposits are no longer present. The grain morphologies (blocky, bubble-wall, irregular and rod-like) and vesicularity of pyroclasts can be used to determine eruption processes and distinguish between ‘dry’ magmatic and ‘wet’ hydrovolcanic eruption-styles. This research is mainly concerned with the characteristics of pyroclasts in basaltic ash/tuff likely formed by highly explosive eruptions, and whether the explosivity of these eruptions was due to magma-water interactions and hydrovolcanism. This study includes a re-examination, and detailed petrographical analysis, of tuffs in the Early Eocene Balder Formation, North Sea Basin, and Harwich Formation, SE England, where the source of tephra produced by explosive volcanism and the extent of basaltic ash dispersal have been contested. Previously, these basaltic tuffs have been attributed to large-scale hydrovolcanic eruptions that occurred during initial sea-floor spreading in the NE Atlantic during the separation of Greenland from NW Europe. These tuffs are compared and contrasted with the basaltic Saksunarvatn Ash (10.3 ka BP) of Grímsvötn Volcano, Iceland, and various non-lava lithologies of the Miocene Columbia River Flood Basalt Province, USA. The primary characteristics of pyroclasts may be modified by abrasion and alteration, particularly during additional transport and deposition. Therefore, the features created directly by the fragmentation and quenching of pyroclasts need to be distinguished from features created by the reworking of this material in the sedimentary environment. It is therefore essential to determine the characteristics of pyroclastic and volcaniclastic materials, which can be achieved by comparing data on the overall deposit characteristics, grain-types, grain-size distribution and grain-morphologies. For example, pyroclastic deposits of ash-grade are dominated by up to 100% igneous/volcanic grain-types, particularly glassy pyroclasts; in thin-section the pyroclasts have smooth-edges and may have undergone limited alteration in modern deposits. In contrast, volcaniclastic deposits may contain a wide range of clast-types, including a greater number of non-volcanic grains, and sedimentary structures such as cross-stratification; in thin-section, reworked pyroclasts of ash-grade (volcaniclastic grains) often have jagged-edges, and varying levels of alteration. This study builds upon the observations and naming schemes of previous authors and proposes a scheme applicable to distal deposits of ash and fine-ash, of both basaltic and silicic composition, including highly altered material.

Predicting the geometry and continuity of clastic units within lava-dominated sequences in volcanic margin settings is problematic as they are typically laterally discontinuous, relatively thin and often poorly imaged in the subsurface. Although such sequences are well known, detailed studies of their lithofacies architecture are rare and poorly constrained, which can result in major challenges to hydrocarbon exploration in these settings. As the demand for hydrocarbons increases, exploration is being focussed on more challenging stratigraphic and tectonic settings, such as volcanic margins. Consequently, it is necessary we enhance our understanding of how petroleum systems interact with volcanic-prone sequences, in order to maximise recovery of hydrocarbons. Using a field analogue in conjunction with remote sensing datasets is fundamental to understanding these complicated systems. This study utilises the Hreppar Formation (HF) in SW Iceland as an analogue to understand elements of petroleum systems to reduce the challenges and risk associated with hydrocarbon exploration within volcanic-dominated basins. The HF at Flúðir, comprises basaltic lavas and interbasaltic sedimentary rocks of Plio-Pleistocene age (3.3-0.7Ma) and provides excellent 3D exposure. This study provides a comprehensive evaluation of the geology in this area and its relevance and importance to hydrocarbon exploration. Detailed field mapping and graphic logging have been combined with field panoramas and photogrammetry to characterise the sequence in detail and to identify the lateral (dis)connectivity of the clastic units, the main lithofacies, the different facies architectures, structural elements and drainage pathways within the HF. The detailed field data presented here are generally all below seismic resolution. In an offshore setting, with currently available technology, it is highly unlikely this level of detail can be captured using remote sensing tools alone. The advantage of using a field analogue such as that of the HF is the level of detail which can be captured. This enables the gap in scale, between field-scale and seismic¬/well-scale to be bridged. It allows models to be ground truthed, which reduces uncertainty and risk, essential to hydrocarbon exploration. This research identifies complex interaction between volcanic, glacial and fluvial systems, underpinned by a strong tectonic influence. >60% of the HF is dominated by sub-aerial basaltic lavas and predicting where lithofacies occur in these types of environments is challenging, however, through initial quantitative analysis of volcanic and sedimentary units in the HF, basic prediction in similar settings is possible. The field data collected in the HF can inform every stage of the development of a hydrocarbon field in a volcanic margin, from determining the architecture of a potential reservoir to defining the main structures and potential fluid pathways as well as deciding how to produce the field.