Absolute palaeointensity data are crucial to investigating the behaviour of the geomagnetic field. Long-term global palaeomagnetic databases are compiled with the aim of documenting the evolution of the geomagnetic field. However the temporal and spatial distribution remains limited, partly due to a lack of 'suitable' material in critical time windows, or poor magnetic behaviour of these rocks during experiments. Therefore it would be useful to have other potential sources of palaeointensity data in the surface rock record. Granitic intrusions occur frequently throughout the geological record, are often well exposed and well dated. However, granitic rocks have not previously been fully exploited in palaeointensity studies, due to their perceived lower primary magnetic content and problems associated with the stability of their magnetic signatures. Plutons show an internal grain-size variation and contain mafic enclaves, xenoliths and sheets derived from the primary melt. Therefore a range of magnetic behaviour, and hence a range of potential suitability for palaeointensity work can be expected within a single pluton. To our knowledge, there are no recorded rock magnetic or palaeomagnetic investigations addressing the question of whether granites are generically unsuitable, for palaeointensity work. To test this hypothesis, three I-type granitic plutons were characterised in terms of their magnetic suitability for palaeointensity analysis - including the Ross of Mull Pluton and Loch Doon Complex, SW Scotland and selected intrusions from the Coastal Batholith, Peru. Characterisation was achieved though extensive rock magnetic, palaeomagnetic and SEM analysis which enabled the magnetic properties of the samples to be determined. 180 samples were investigated using the Coe-modified Thellier technique to determine whether reliable palaeointensity data can be obtained. Magnetic characterisation and SEM analysis reveal that the magnetic mineralogy of the granitic intrusions is dominated by multidomain (MD) Ti-poor titanomagnetite. Exsolution textures observed in the Fe-Ti oxide grains are responsible for creating grains with SD-MD grain sizes. Stable univectoral remanences are usually accompanied by narrow unblocking temperatures where most NRM is lost between 560- 580°C. This makes obtaining acceptable PI data difficult, but by no means impossible. PI experiments were of variable success. Experiments including pTRM and pTRM tail checks and standard acceptance criteria were used to assess the quality of the results. The Ross of Mull rocks yielded no PI determinations. However, the Loch Doon Complex and intrusions from the Coastal Batholith were more triumphant with success rates of 28% and 57% respectively. The Loch Doon pluton (408Ma) is calculated to have a pluton average 8.2[mu]T with standard deviation 4[mu]T. The main reasons for failure of PI experiments are weak NRM, alteration and unstable MD behaviour. Experimental success correlates with the perceived geological complexity at each field area, where it is observed that simpler intrusions with less complicated cooling histories yield rocks with a: more stable magnetic signature and allow PI data to be derived. Results indicate that the more mafic rocks sampled in each pluton produced the best quality PI data. PI estimates were made on samples from Peruvian intrusives. The Anta ring dyke and Chasquitambo pluton give a site average of 15[mu]T with standard deviation 13.5[mu]T. Large deviation is caused by a single estimate, which at 46.7±18.4[mu]T is significantly different from the values found from other sites. Remaining sites have PI within error, however it should be noted that according to the K-Ar dates (Wilson, 1975) emplacement of the two separate intrusions occurred millions of years apart, 70.7±1.6Ma and 61±0.7Ma respectively. Samples from the Sayan pluton (61.2±0.4Ma) yield an average PI 25.4[mu]T ±7.7[mu]T. Arai plots are dominated by curvature, pTRM checks and rock magnetic experiments indicate that curvature is not caused by alteration and can be attributed to MD phenomena. PI estimates are made using the end-point method and from linear segments were possible, consistency between the two methods was demonstrated. This research reveals the potential of I-type plutons to provide reliable palaeointensity data.However, the PI data presented here must be considered as preliminary as no cooling rate or anistropy corrections have been applied.

A chronostratigraphic framework based on foraminiferal biostratigraphy, integrated with carbon-isotope stratigraphy, has been generated for the Upper Albian - Lower Campanian interval of the eastern and western basins of northern Venezuela. The successions are composed of occasionally phosphate-rich calcareous sandstones and shales to the SSW, and foraminiferal organic-rich mudrocks and limestone in more northern areas (Alpuf-6 and TOT-3 wells in the west; Chimana Grande Island and Querecual River sections in the east). Biostratigraphic resolution is very poor in the SSW areas due to deposition in shallow-water conditions. To the north, a palaeoslope reconstruction of the Cretaceous passive margin, integrated with foraminiferal biofacies and abundances of planktonic foraminifera morphotypes, indicates that bathyal conditions prevailed, with dysaerobic or anoxic bottom-waters being caused by high rates of surface-water productivity. These were associated with an intermittent upwelling regime and palaeobathymetric barriers that restricted circulation, causing stratification and accumulation of vast quantities of organic-rich sediments. These adverse conditions caused a paucity of keeled planktonic foraminifera and impoverished benthonic faunas, resulting in low-resolution biostratigraphy for the Querecual and La Luna formations, which range in age from Late Albian 'Roralipora ticinensis' Zone to Santonian 'Dicarinella asymetrica' Zone. A chemostratigraphic study demonstrates that the highest TiO[sub]2. A1[sub]2O[sub]3 and Fe[sub]2O[sub]3 percentages are observed in the Upper Albian, Cenomanian and Santonian, whereas Sr/Ca ratios, despite diagenetic effects, show increasing trends in the Cenomnanian and decreasing trends from the Santonian up to the Campanian in most sections. Organic-rich facies exhibit high (>20%) TOC values, particularly in the Upper Albian to mid-Cenomanian and in the Turonian. A stable carbon-isotope reference curve for organic matter ([sigma][sup]13C[sub]org) generated for the Upper Albian - Lower Campanian interval, shows the [sigma][sup]13C Albian-Cenomanian Boundary, MCEI, CTB, Holywell, Lulwoth, Ruund Down, Glynde, Pewsey and Hitch Wood isotope events, and other Coniacian and Santonian events identified in England. Despite difficulties arising fromn the use of different biostratigraphic schemes in Boreal and Tethyan sections, the [sigma][sup]13C reference curves from England and Venezuela display remarkably similar trends that confirm the usefulness of [sigma][sup]13C chemostratigraphy, combined with biostratigraphy, as a powerful basin analysis and correlation tool.

No description available.

There is an urgent need to develop robust tools and policies for stability and hazard risk assessments in order to manage upland peat landslides in locations such as the British Isles where they have frequently occurred and caused harm to the environment. One of the particular difficulties is that reliable values of peat strength are difficult to obtain. The objectives of this research were to establish the nature of any relationships between the strength characteristics and the botanical, physical and chemical properties of the peat, and to determine whether palaeobotanical analyses of samples of the basal peat can provide a reliable indication of potential instability in upland blanket bogs. The research was carried out at the Straduff Townland (Co. Sligo), Slieve Anierin (Co. Leitrim) and Slieve Rushen (Co. Cavan) landslides, all located in northwest Ireland, from the margins of which monolith and core peat samples were collected. Standard and validated paleobotanical, chemical and geotechnical protocols, modified or refined where necessary to suit the nature of the peat, were used in the study. The triaxial, direct shear and tensile strength tests were conducted using experimental very low stress conditions in order to fully replicate in-situ conditions. The reliability of the measured strength parameters was examined by performing deterministic and probabilistic stability analyses of the failed slopes using industry-standard „limit equilibrium‟ software (SLOPE/W). The nature, extent and spatial distribution of the hydrocarbons unexpectedly found in the basal peats during the fieldwork were also investigated. This research found that blanket peat dominated by monocotyledons (with mainly E. vaginatum) is likely to be susceptible to failure because its „effective structural properties‟, specifically the high degree of humification and low fibre content of its basal peat, cause it to have very low strength and also therefore a very low bearing capacity. Furthermore, monocotyledons or its remains in peat have morphological, chemical, biological features that can promote bogflow-type failure. These may include for example (i) their parallel and elongated leaf veinations that promote flow, (ii) the genesis of hydrocarbons such as bitumen from their lignified tissues and (ii) being host to a hydrocarbon-producing aphid Colopha compressa. Laboratory measurements of undrained strength of the weak basal peats were consistently < 3 kPa, and deterministic stability analyses revealed that the value of the tensile strength can be used as an indicator of the undrained shear strength. A new classification (i.e. "the modified fibre content scheme") and a modified procedure for assessing upland peat failure for construction projects has been proposed based on peat fibre and humification characteristics and their apparent influences on peat strength. Deposits of hydrocarbons such as bitumens within the basal peat constitute a previously unrecognised factor that probably contributed to the occurrence of the studied landslides due to their hydrophobic properties.

Carbonatite magmas characteristically expel fluids into the surrounding country rock, creating metasomatised alkali-rich fenite aureoles. This thesis examines evidence for the mobility ofhigh field strength elements (HFSE), including the rare earth elements (REE), niobium and zirconium into these fenite aureoles in order to provide a better understanding of element mobilisation, transportation and precipitation. The study is timely because the REE and Nb are recognised as critical metals. The REE, in particular, are used in green technologies, and have grown in importance in recent years. The combination of the concentration of REE mines in China, associated export restrictions and a severely limited scope for substitution of these elements, has highlighted the challenges of securing adequate supplies and of a better management of resources, together with the need for an improved knowledge of the processes by which mineral deposits are enriched to economic grade. The approach used here was to study fenite aureoles around two Cretaceous carbonatite complexes at Chilwa Island and Kangankunde in the Chilwa Alkaline Province of southern Malawi by re-examining samples held in the collections of the Natural History Museum, London (BM1968 P37 and BM1957 1056). The geology of the complexes had already been well described by M. Garson and A. Woolley but the results of recent studies elsewhere suggested that it should now be possible to explore the fenitising process in more detail. Kangankunde is a rare earth-rich ferroan dolomite carbonatite, subject to active exploration for the REE. Chilwa Island contains a wider range of carbonatites, including apatite-, magnetite-bearing calcitic carbonatite, and REE mineral-bearing ankeritic and sideritic carbonatites. The presence ofassociated silicate rocks is minor at both these complexes. Samples were selected from across the fenite aureoles to represent areas of differing intensity and style of metasomatism. Whole-rock analyses were made to assess compositional changes across the aureole. Mineralogical studies by SEM-EDS, EPMA, LA-ICP-MS and SEM cathodoluminescence permitted the identification of mineral assemblages, the establishment of paragenetic sequences and also the characterisation of the REE compositions in apatite, zircon and the RE-bearing minerals from zones of varying degrees of alteration within the aureole. Fluid properties were further explored by fluid inclusion studies of secondary inclusions in the country rock quartz. Apatite and zircon in the fenite were dated by fission track analysis and a U-Pb LA-lCP-MS method, respectively, to determine their relationships with the carbonatite. At both complexes, fenite rocks contain micro-assemblages of minerals visible by backscattered electron imaging but not reported in previous studies. Examples include the assemblages of zircon, ilmenite, rutile, apatite and monazite found in veins of up to 500 um width in the sodi-potassic outer fenite at Chilwa Island, and the associations of strontianite, RE-minerals and carbonates in mm-sized veins in the more highly metasomatised parts of the aureole at Kangankunde. Alteration and dissolution-precipitation reactions seen in these micro-assemblages suggest that multiple fluid events occurred in the fenite aureole. The presence of alkaline minerals (aegirine, albite, K-feldspar, arfvedsonite) indicates pervasive fenitisation by fluids expelled from the carbonatite over distances of more than a kilometre. The micro-assemblages provide evidence that fluids were able to mobilise, transport and precipitate the HFSE and REE outwards over a similar distance into the country rock but that for the REE this event followed an earlier fenitisation by alkaline fluids. It is likely that fluids from more than one carbonatite have contributed to the variation in mineralogy and mineral composition. Fenite rocks and minerals have lower light REE:heavy REE ratios than those of the carbonatites in the core of the complexes. This cannot be explained by simple mixing between carbonatite and country rock end members, and fractionation of the REE during fluid transport is therefore invoked with relative preferential mobilisation and deposition of the mid to heavy REE. Zircon and apatite in the mineral assemblages at Chilwa Island appear petrographically to be co-eval. However, although fission track dating confirmed a carbonatitic age of c.130 Ma for apatite, the U-Pb dating of associated zircon produced ages of between 520 and 770 Ma and so zircon must be part of the original country rock rather than having co-precipitated with apatite. In the less altered fenites, zircon is stable, and at Chilwa Island, appears to encourage the nucleation of carbonatite-derived mineral assemblages. In contrast, zircon is unstable in higher- grade fenite at both complexes where metasomatising fluids were most intense. Zirconium is thus released from highly altered rocks and, rather than forming alkali zirconosilicates as happens in alkaline complexes, it appears to be transported outwards and is re-precipitated as a secondary, sub-micron zircon population in low- grade fenite. Interpretative models require the ingress of multiple fluids at each complex. Early alkaline fluids were more extensive and predominantly sodic. Later potassic fluids produced more intensive alteration in the inner aureole. The mineral assemblages were precipitated in veins in the aureole by fluids carrying the REE, which were expelled in multiple episodes from the different carbonatites at each complex, both before and after alteration by potassic fluids. At Chilwa Island, modelling suggests that early REE mineralisation in the fenite rocks from the outer carbonatites of the complex occurred after pervasive initial alkaline alteration by sodic fluids. This was overprinted by intense potassic alteration in the innermost fenites. The subsequent relative MREE and HREE enrichment in the aureole is attributed to fluids from the late-stage carbonatites. At Kangankunde, fluid events produced the same pattern of alkaline alteration followed by HFSE mineralisation, but here enrichment in the MREE and HREE occurred early, after the sodic alteration, with later fluids precipitating minerals with higher LREE:HREE ratios and substantial carbonate. As at Chilwa Island, the distinct characteristics of each mineralising fluid show that it is likely they were expelled from different carbonatites in the complex.

The Istria ‘Depression’ or sub-basin of offshore Romania lies at the intersection of the trans-European Tornquist-Teisseyre ‘Zone’ and the Black Sea back arc basin, just outboard of the East Carpathian orogenic welt. Its Late Mesozoic-Cenozoic succession records an extraordinary cpolyphase history of subsidence and sedimentation, interrupted by several quite spectacular 2nd /3rd order erosional unconformities, reflecting the interplay between these teetonic domains. The unconformities divide the succession into a number of stratigraphic sequences. The sub-basin first developed as a transtensional rift in the Triassic-Early Jurassic, evolving into a narrow oceanized trough in later Jurassic. This was tilted west during the Early Cretaceous by uplift and rifting in the Western Black Sea and the residual Late Jurassic topography was filled and buried by a west-facing clastic-evaporite wedge. Late Aptian- Albian post-rift subsidence and spreading in the Western Black Sea imposed a strong easterly tilt, encouraging the partial evacuation of its Early Cretaceous sedimentary fill by gravity-driven mass wastage. The incised valley topography was subsequently buried in the later Cretaceous and Early Cenozoic. During the mid-Late Cenozoic, the Black Sea basin experienced intermittent periods of partial to complete isolation from the world ocean and significant base-level drawdown. The first major sea level fall occurred in the Eocene when the Istria ‘Depression’ was deeply incised, to be healed by Oligocene shales during the subsequent rise. Yet another period of drawdown and exposure occurred in mid-Miocene With extensive shelf margin mass wastage and erosion, followed by reflooding and deposition of a transgressive backstepping sequence in mid-late Miocene. Messinian drawdown in the Mediterranean caused a further period of isolation and falling base level. The shelf margin Was again exposed and experienced widespread mass wastage and slumping. A marine connection was re-established in late Messinian. Rising sea level eroded the earlier slumped sequence and the margin was healed by a lowstand prograding wedge in late Miocene-early Pliocene. This was followed by shelf sedimentation in the Plio-Pleistocene periodically interrupted by canyon incision events, testifying to continued climatically or tectonically- imposed base level fluctuations. Several direct and indirect tectonic factors were responsible for valley/canyon incision within the Istria Depression and erosion of the Romanian Black Sea shelf margin. These include; (1) the local structural framework (2) direct tectonic uplift and tilting and (3) more indirect tectonically imposed isolation encouraging significant base level falls.

A synthesis of Palaeozoic petroleum systems within the Libyan part of the Ghadamis Basin is presented, based upon data from over 60 wells and approximately 300km of 2D seismic lines. Cross-sections and maps have been constructed to illustrate the structural and stratigraphic evolution of the basin. The techniques of sequence stratigraphic analysis have been applied to these cross-sections to describe the stratigraphic architecture of the Silurian-Devonian succession. The maps and cross¬sections have been analysed to define the maturation and expulsion history of hydrocarbons from the primary Silurian-aged source rocks. Optimum migration pathways have been modelled through time, assuming simple hydrostatic and lithostatic conditions. The results correlate well with the known stratigraphic and geographical distribution of the existing oilfields in the basin. The distribution of oil and gas fields has been strongly influenced by the stratigraphic architecture of the Silurian-Devonian succession. Basin reconstructions and burial history models have been inade, and three expulsion peaks from the basal Tanezzuft Formation source rock have been identified. These precede major periods of Hercynian, Austrian (late Early Cretaceous) and Alpine (mid-late Tertiary) uplift and exhumation. It is suggested that hydrocarbons generated in the Late Palaeozoic were subsequently dispersed during Hercynian uplift and erosion. Some hydrocarbons expelled prior to the Austrian uplift may still be reservoired locally, but most of the existing fields are believed to have been charged in the Late Cretaceous and Early Tertiary. Hydrocarbon accumulations in the Upper Silurian Acacus Formation, the Lower Devonian Tadrart Formation, and later Devonian reservoirs have been charged from a basal Silurian (Tanezzuft Formation) 'hot' radioactive shale source rock. The Acacus and Tadrart sandstones provided regional migration conduits sealed by intra-Acacus, intra-Devonian (Emghaet Formation) and Permian (Bir Al Jaja Formation) shales. Regional stratigraphic continuity of these migration conduits encouraged the development of low to moderate impedance petroleum systems dominated by lateral migration. Three discrete petroleum systems have been recognized: • An Acacus- Tanezzuft system to the north in fault and subcrop traps • A central basin, Tanezzuft-sourced system with Upper Silurian, Devonian and Lower Carboniferous reservoirs in low relief, fault-controlled traps • A Tadrart-Tanezzuft system to the south in simple fault traps with an associated reservoir sequence in the Upper Ordovician. This integrated analysis provides the basis for understanding the lower impedance (entrapment efficiency) and smaller size of the oilfields in the Libyan sector of the Ghadamis Basin, compared with those further west in eastern Algeria (Berkine Sub-basin). More importantly, this synthesis should help to improve future exploration efficiency in the Libyan Ghadamis Basin.

Non-Newtonian flow in heterogeneous media is of enormous theoretical and industrial importance. This phenomenon is studied to reveal macroscopic effects that arise due to the interaction between the non-linear flow behaviour and the spatial variation of the medium through which it is forced to move. The heterogeneity is achieved by using porous granular media, which is naturally non-homogeneous. The non-Newtonian properties of the fluid may have many causes and is an intrinsic property of the fluid that is used: One way of achieving it is by studying dense slurries of neutral particles or naturally occurring magmatic flows. Another way is to study the case where the flow is dominated by its ionic content and where the double layer thickness (the effective size of the ionic entities) is of the order of magnitude of the pore size. All cases studied in this thesis pertain to slow flow (low Reynolds number), though the fluid may be compressible. The variations in the flow are calculated in first order and these turn out to be coupled to the spatial variations in the porous medium. In this way structure formation is predicted. The structures may be either aligned with or may be perpendicular to the mean flow direction. 'Experiments to decide on which regime is relevant have been conducted. The genesis of structure formation is studied as a temporal development by considering a compressible flow. The constitutive equation that is required to couple the compressibility to the flow parameters is investigated. Two possible mechanisms have been identified: compressibility coupled to the pressure field and compressibility associated with the fluctuations in the flow. Using linear analysis the structure formation patterns associated with these two mechanisms are established for the steady state. Flow of ionically laden fluids has also been studied. Experiments done at Loughborough University (Department of Chemical Engineering) on electrowashing of filter cakes has been used to prove a major macroscopic effect. This effect takes place when the ionic diameter (which is approximately twice the double layer thickness) is of the order of magnitude of the pore size. A phenomenological set of transport equations has been set up. These contain coefficients, such as transition probabilities and mean ionic flow rates, that can be obtained from experiments by doing a first order solution of the equations for short times. A more involved numerical solution is also supplied and confirms the initial analytical estimates.

This thesis provides an alternative method to for mapping soil erosion. The method is conducted in a small study area of 40 km2 in the Sorbas Basin, Almería province, Southeast Spain. Soil erosion is one of the most destructive land degradation processes and can often lead to serious environmental problems. It is important to implement appropriate management strategies to meet these challenges at a range of scales. However, prior knowledge of erosion processes and the extent to which they operate spatially is often limited and, traditional methods of soil erosion mapping are often time and labour intensive. This thesis explores the use of two Artificial Intelligence (AI) techniques for soil erosion mapping; Artificial Neural Networks (ANNs) and Decision Tree Classifiers (DTCs). The opportunities for employing such methods relate in part to their non-linear capabilities, their ability to learn in an inductive manner and incorporate multi¬source data sets. AI training and test data were collected from 520 individually sampled locations within the study area. At each site the dependent variable erosion was estimated, as were a range of independent variables through field study. Two Digital Elevation Models were developed. Laboratory analysis was also undertaken to explore the physico-chemical processes relating to soil dispersion and to determine the applicability of a soil sodicity meter developed by the Co-operative Research Centre for Soil and Land Management in Adelaide, Australia. Results demonstrate that classification accuracy.and overall performance is strongly dependent on the independent and dependent variables used, with the more expensive field collected data providing improved variables to those extracted from the Digital Elevation Models. Discriminant Analysis (DA) classifications were also employed to provide a linear comparison to the AI techniques, and performed comparably well. In the Artificial Neural Network classifications the composition of the training set was seen to exert significant bias, leading to poor performance and often misleading results. Laboratory analysis highlights the complex physico-chemical relationships associated with soil dispersion. The findings also indicate that no discernible relationship exists between the sodicity meter and standard laboratory procedures employed to measure the sodic properties of a soil. The thesis demonstrates the potential for employing these methods for erosion risk analysis and the ability of inductive approaches to formulate rules that may enhance current levels of understanding associated with soil erosion processes. Mapped outputs produced by these methods may prove valuable in the management of landscapes susceptible to soil erosion.

This thesis examines the fertility and women's status in Bosnia and Herzegovina. It reviews the differences in population growth rates among the world's major areas during the 1950-2000 and the fertility characteristics and family policy in Europe. The fertility transition across Europe is highlighted. All European countries have experienced considerable decline of fertility and by the end of the 20th century the rates were far below replacement levels in almost every country. The demographic change and fall in fertility in Bosnia and Herzegovina and in neighbouring states is marked. In so doing, it applies the demographic period analysis of fertility rates in the second half of the 20th century and in recent years and the examination of total fertility and age specific fertility rates shows that there was variation in the declining dependent upon the extent of female education and occupation. The historical aspect of female positions in Bosnia-Herzegovina's society is illustrates that fertility transitions are initiated by the improved status of women and their increased ability to determine own fertility. The correlation between fertility and urbanization and income per capita suggests that as income or the level of urbanization rises then the fertility rate falls. Ethnic affiliation to some extent corresponds with other socio-economic factors impacting on fertility level. Total fertility rates vary across urban and rural place of residence generally, but higher fertility rates are found in more urban then in rural areas. The greater involvement in the impersonal market sector and better professional position, the lower are the fertility preferences and lower actual fertility. The large body of evidence showing how high fertility levels is related to economically less developed municipalities helps to elucidate the relationship between a women's occupation and total fertility rate. The post-war period is characterized by new women's activism but participation of women in different sphere of public life and their general status are still not satisfactory. The more emphasized decline in natality and fertility rates in recent years is the consequence of unenvious socio-economic and political environment in Bosnia and Herzegovina.