This study presents a detailed consideration of the effects of geometry, U- and Th-zonation and diffusion on zircon (U-Th)/He ages. The errors introduced by assuming homogeneity are quantified, and the difficulties associated with the characterisation of U and Th zonation in zircon samples are addressed in a qualitative and quantitative assessment. When these issues are fully considered, the (U-Th)/He age distribution of unknown samples can be understood, and (U-Th)/He ages can be interpreted with confidence. Using these more rigorous interpretive techniques, it has been possible to accurately determine the (U-Th)/He ages of zircons from the Palaeogene Hebridean Igneous Province. This data has been used in conjunction with apatite thermochronometry (fission track and (U-Th)/He) to constrain the low temperature cooling history of the region. In the Hebridean Igneous Province denudation has removed much of the basaltic lava pile and has exposed the plutonic complexes emplaced at its base. This thermochronological investigation of these plutonic sequences shows that the initial cooling was very rapid. This is consistent with field evidence for shallow level emplacement, accompanied by extensive hydrothermal activity and syn-, and post-intrusive denudation. The new data from the zircon (U-Th)/He, apatite fission track, and apatite (U-Th)/He thermochronometers identifies a previously unresolved pulse of magnetic activity that occurred at approximately 47 Ma, significantly after the initiation of rifting, and the cessation of voluminous shallow level intrusion in the Hebridean Igneous Province. The timing of a short-lived low temperature event observed in the plutonic units on the islands of Rum (80 - 90°C peak temperature), and Skye (120 - 180°C peak temperature), correlates with a cooling episode of more than 200°C at the St Kilda Central Complex, 100 km further to the west.

Evidence of Holocene marine transgression and regression in South-West Scotland is exhibited in the stratigraphical record of present and former coastal deposits. Remnant areas of Holocene coastal (including marine) sediments are preserved at the head of marine inlets and estuaries along the northern shore of the Solway Firth and may extend up to 10km inland, indicating significant changes in coastal configuration as a result of marine transgression and regression during the last 10,000 years.At the head of Wigtown Bay, former Holocene coastal deposits are well exposed along the incised meanders of the upper Cree estuary and Palnure Burn. Referred to in the literature as `carse deposits', these sediments are products of several different environments.During late-Pleistocene times and very early in the Holocene Epoch, the upper Cree estuary area north of Creetown was a low lying boggy environment. The area was marginally marine in character. The exact position of the palaeo-Cree is uncertain but the river flowed in a general NW to SE direction and may have been braided. The marine waters of the Holocene marine transgression flooded northwards, penetrating the upper Cree estuary c . 7,900 years B.P., leading to the deposition of low to high tidal-flats. By 6,480107 years B.P. local regression had begun and seaward progradation of high upper tidal-flats and marsh had started. This environmental situation prevailed until 5,000 years B.P., when incision occurred and terrestrial conditions became dominant.In the lower Cree estuary, waters of the Holocene marine transgression initially flooded the lower courses of rivers and rose to flood the hollows in the uneven surface of the fluvio-glacial deposits flanking the estuary.Accumulation of low tidal-flat deposits gave way to upper tidal-flat and marsh deposits as the transgression diminished. The transgressive event was shortlived. Sediments were deposited at the `feather edge' of the transgression. North of Creetown and the Moneypool Burn, upper tidal-flat and marsh deposits rest directly on fluvio-glacial deposits. As regression occurred, seaward progradation and incision of the carse deposits proceeded.A pause in regression c . 2,000 years B.P. resulted in certain morphological features observed in the Cassencarie area. Stormy conditions resulted in the re-working of marginal fluvio-glacial deposits to form a spit, and to the south (between Cassencarie and Carsluith) coarse marine sands and gravels were transported landwards to form shore-parallel and oblique bars. At Carsluith, similarly-derived material forms a thinly-developed beach blanket. Recession of the sea has proceeded since 2,000 years B.P. to the present-day.

This thesis has investigated the geological origin of diamonds from the Ural Mountains. A set of inclusion-bearing diamonds from alluvial deposits in the western part of the Urals was characterised on the basis of their morphological features, nitrogen contents and nitrogen aggregation states, carbon and nitrogen stable isotopes, mineral inclusion geochemistry and radiometric isotopic ages of the inclusions. The vast majority of the studied diamonds are rounded dodecahedra, which indicates that the diamond population has experienced major resorption after crystallisation. The majority of the diamonds are affected by radiation damage and display evidence of transportation. Non-abraded diamonds exhibit similar surface features to those abraded, so they are probably of similar origin. The studied inclusion-bearing set of diamonds shares some characteristics with the overall, mostly inclusion-free, diamond population from the Ural Mountains. This similarity in physical characteristics strongly suggests that the Ural diamonds are all part of a single population. A Fourier Transform Infra-Red (FTIR) spectroscopy study allowed both the concentration of nitrogen and the aggregation states of this element to be quantified. Diamonds from other known primary deposits in the East European Craton (EEC) have FTIR signatures that do not match that of the studied population. Nitrogen thermometry results suggest that the Ural diamonds probably crystallised under similar pressure-temperature conditions. If a similar overall regime of formation for the Urals alluvial diamonds is considered, then a single primary diamond source or a spatial proximity between primary contributory sources seems likely. The variations in δ15N – δ13C measured in the Ural diamonds of the peridotitic and eclogitic paragenesis suggest derivation from a similar, initially homogenous, mantle carbon source which has been subjected to metasomatic-induced isotopic fractionation. However, for some δ15N-enriched – δ13C-depleted eclogitic diamonds, the possibility of crystallisation from subduction-related metasomatic fluids/melts cannot be excluded. Based on the chemical composition of syngenetic mineral inclusions recovered from the Ural diamonds, the eclogitic paragenesis (60%) dominates over the peridotitic (26%), with a minor websteritic assemblage also present (2%). The remaining 12% are diamonds with sulphide inclusions of unknown paragenesis. The chemistry of the mineral inclusions almost completely overlaps that of previous electron microprobe studies of inclusions in diamonds from worldwide localities. Geothermobarometric calculations show an overall agreement between the equilibration conditions of the three inclusion parageneses. The Ural diamonds crystallised at temperatures of 1050-1300°C, at minimum depths of about 165 km, within a diamondiferous lithosphere extending to at least 230 km at the time of diamond formation. The Re-Os isotope genesis age data for syngenetic sulphide inclusions and the 40Ar/39Ar laser probe eruption ages of syngenetic clinopyroxene inclusions were determined. Six eclogitic sulphide inclusions, two of which coexist in the same diamond, gave an isochron age of 1280 ± 310 Ma which may be associated with rift-related magmatism that affected the EEC at ca. 1.3 Ga. The determined genesis age is also similar to genesis ages reported for eclogitic diamonds from a number of mines in southern Africa, and this is probably indicative of a global diamond formation event at that time. Five eclogitic clinopyroxenes recovered from four diamonds yielded similar 40Ar/39Ar ages averaging 472 ± 28 Ma, which likely approximate the time of source kimberlite/lamproite eruption. This age indicates that the Ural diamonds are not derived either from the diamond-bearing kimberlites of the Siberian craton, nor from presently known Russian and Finnish kimberlite provinces on the EEC. An integrated model for the genesis, eruption and accumulation of the Ural diamonds in the context of the evolution of the EEC is proposed. The Urals placer deposits are mainly confined to 407-397 Ma sedimentary rocks along the western side of these mountains, with diamond size distribution indicating sediment transportation at that time generally from the north-west. The diamondiferous sedimentary accumulation in the Urals is envisaged as being analogous to that presently found along the Namaqualand / Namibian coastal belt in the western margin of southern Africa. During the construction of the Ural Mountains, the diamondiferous sediments became part of the western accretion zone when the EEC united with the Kazakhstan and Siberia plates during late Devonian through to late Triassic times. The evidence presented in this thesis suggests the existence of an undiscovered kimberlite/lamproite primary source, probably on the Volgo-Uralia crustal segment of the EEC, which gave rise to the Urals diamond deposits.

An extensive and detailed overhaul of the present classification of the Marrolithinae is undertaken to produce a clear taxonomic framework from which to understand the phylogeny and biogeographical history of the subfamily. Historically, marrolithine species have been defined using a strongly typological approach which has increasingly proved unworkable as species show ranges of variation in morphology that have led to uncertainty in the identification of specimens and has therefore lowered their stratigraphical usefulness. The lack of appreciation of morphological variation has resulted in the naming of a great many more species than are probably actually present in the fossil record. Extensive museum collections have been analysed supplemented by field sampling within Wales and Shropshire and comparison of field locations and horizons. A large collection of over 2000 specimens of Llanvirn to Ashgill Moroccan Marrolithinae was studied for the first time. This material has been important in the reclassification of the Marrolithinae. These samples contain the earliest Onnia specimens and have therefore thrown light on the Deanaspis and Onnia specimens and have therefore thrown light on the Deanaspis and Onnia lineage as presently understood. The Moroccan samples also contain the earliest representatives of the new genus Hammannaspis. The Moroccan species played an important role in the distribution of the Marrolithinae around proto-Tethys. The re-evaluation of the classification of marrolithine genera and species has included the first cladistic analysis of a trinucleid subfamily, detailed analysis of variation in fringe pit development within samples and taxa and consideration of the palaeogeographical relationships between the marrolithine taxa in space and time. These differing approaches have led to the production of a more constrained and easier to use classification which will enhance the stratigraphical usefulness of the Marrolithinae.

The cretaceous ostracods of Iraq are poorly known, so the aim of the project was to study their taxonomy and to discover their value in correlation between wells in Iraq and between Iraq and neighbouring countries. The Cenomanian-Santonian ostracods of the superfamily Cytheracea were studied in detail from five wells in central and southern Iraq (East Baghdad Well-3, South Rumaila Well-104, Safawi Well-1, Ghalaisan Well-1, and Kifl Well-2). 5 families, 6 subfamilies, 28 genera, 4 subgenera and 74 species were discovered. Two new genera, Iraqicythereis and Archeocosta (the latter published by Al-Bashir and Keen in 1984 during the preparation of this thesis) and one subgenus Peloriops (Hemipeloriops) are proposed; of the 74 species described 58 are new. Four ostracod biozones and three subzones are proposed for the areas studied on the basis of the Cytheracea ostracods; these are arranged from the base to the top as follows: Veeniacythereis streblolophata - Veeniacythereis maghrebensis - Total Range Zone (A-1); Dumontina? mdaouerensis - Partial Range Zone (A-2); Veeniacythereis ibnalhaithami - Partial Range Zone (A-3); Peloriops (Peloriops) alrazii - Partial Range Zone (A-4). The Veeniacythereis streblolophata - Veeniacythereis maghrebensis - Total Range Zone is subdivided into three subzones: A - Glenocythere bahrreinensis - Total Range Subzone (A-1a), B - Soudanella? alkhansai - Assemblage Subzone (A-1b), and C Cythereis alfarazdaki - Assemblage Subzone (A-1c). The ages of the zones and subzones have been determined from a study of the diagnostic ostracod species and stratigraphic position. A Cenomanian age is assigned to A-1 zone; the A-1a and A-1b subzones are of Lower Cenomanian age; a Lower Turonian age is suggested for the A-2 zone; Upper Turonian-Coniacian for the A-3 zone; and a Santonian age for the A-4 zone. The ostracod zones and subzones have been recognised in each of the wells studied. The age of the formations studied has been determined on the basis of the ostracod fauna and stratigraphic position. The upper part of the Mauddud Formation, and the Ahmadi Formation are assigned to the Lower Cenomanian; the Rumaila Formation is placed in the Upper Cenomanian; the Mishrif Formation is placed in the Upper Cenomanian to Lower Turonian; the Kifl Formation is placed in the Lower Turonian; the Khasib Formation is placed in the Upper Turonian-Lower Coniacian; the Tanuma Formation is placed in the Upper Coniacian, although it may include strata of Santonian age in some localities; and the Sadi Formation is assigned to the Santonian. The Ahmadi/Rumaila contact in Ghalaisan Well-1 is placed at the top of the Soudanella? alkhansal subzone. The lower part of the Rumaila Formation in East Baghdad Well-3 is contemporaneous with the Ahmadi Formation on the basis of the occurrence of the Glenocythere bahreinensis Subzone, and is considered to be of Lower Cenomanian age. In Kifl Well-2 the Maotsi Formation is probably of Upper Cenomanian age and the Mahilban and Fahad Formations may be of Lower Cenomanian age. The base of the Khasib Formation is marked by the appearance of many new ostracod species and genera such as Acanthocythereis, Brachycythere, Buntonia, Paracytheridea, Protobuntonia and Phymacythereis. This indicates a major faunal break between the Mishrif/Kifl Formation below and the Khasib Formation above. This faunal break is marked by an unconformity referred to as the Aruma-Wasi unconformity which is recognised throughout the Arabian Gulf. The ostracod biozones of Iraq have been correlated with corresponding zones in other Middle Eastern and North African countries. Problems of variation in the size of some ostracods have been studied. There is a considerable range in size of Peloriops (Peloriops) ulosa, Rehacythereis arabica, Brachycythere basrahaensis sp. nov., Archeocosta alkhazwinii, Veeniacythereis maghrebensis, and Veeniacythereis ibnalhaithami sp. nov. The size range appears to be continuous, and the smaller specimens are considered to be adult. This size variation appears to exclude precocious sexual dimorphism as well as the possibility of larger and smaller forms belonging to two closely related species. It is difficult to determine whether the size variation is due to environmental or genetic causes. Intra-specific variation in ornamentation of the following species has sbeen studied: Iraqicythereis Kadisiya gen. et sp. nov., Veeniacythereis ibnalhaithami sp. nov., Cythereis? ibnyunusi sp. nov., Peloriops (Peloriops) sphaerommata, Peloriops (Hemipeloriops) djabirbnhaiyani sp. nov., and Metacytheropteron berbericus. This variation may be continuous or discontinuous. In the first case it is difficult to recognise distinct morphotypes, but in the second case it is possible to separate them into distinct morphotypes. The morphotypes appear to represent a case of stable polymorphism. The variation is believed to be genetically controlled. The environments of deposition have been determined by using the characteristic ostracod species and other fauna (e.g. foraminifera), and type of sediment. The Ahmadi Formation was deposited in an open, shallow, neritic environment with restrictions in some areas. The Rumaila Formation is distinguished by its low species diversity and poor fauna, but this is considered to be due to preservation rather than environmental conditions. Generally the Rumaila Formation represents deeper water conditions than those of the Ahmadi Formation, becoming shallower with restrictions from the sea in some areas. The Mishrif Formation indicates open shallow water neritic conditions followed by a shallowing phase associated with oscillations of sea level, or with an influx of fresh water. The Kifl Formation represents shallow water conditions partly connected with the open sea, accompanied with the development of lagoonal areas. The Khasib and the Tanuma Formations indicate open shallow marine conditions (infra-neritic), but in some areas (in East Baghdad Well-3 and Kifl Well-2) coastal conditions are suggested, perhaps with restricted access to the open sea because of the presence of a poor ostracod fauna dominated by Ovocytheridea.

Geochemical analysis of the volcanic interval in Well 214/4-1, Faeroe-Shetland Basin, has enabled a correlation to the Lower Basalt Formation of the Faeroe Islands, ca. 240 km to the W. The volcanic interval consists of a ca. 450 m thick sequence of hyaloclastites, which are overlain by a ca. 50 m thick subaerial lava sequence. This volcanic interval is interpreted to have formed at a palaeoshoreline environment, where subaerial lavas flowed from the land surface into a substantial body of water at least 450 m deep (i.e. the Faeroe-Shetland Basin at that time), resulting in the quenching and fragmentation of magma to product the hyaloclastities. Well 214/4-1 is <50 km to the SE of the Faeroe-Shetland Escarpment, which has previously been interpreted as a hyaloclastite delta, thus implying that there a number of unrecognised hyaloclastite units within the Faeroe-Shetland Basin and that the coastline was steadily encroaching W/NW, towards the Faeroe Islands during the volcanic interval. The overlying ca. 10 m thick Coal-bearing Formation (CBF) represents a significant hiatus in the volcanic activity at the end of LBF times. Erosion and subsidence of the lava field led to the development of an expansive lacustrine environment, which resulted in the accumulation of plant material and associated detritus and chemical sediments, mainly ironstones, and the formation of mineable coal seams. Petrographic and geochemical analysis of siderite spherules within the ironstone beds from two localities on Suðuroy have helped to define margin- and centre of-lake environments, at least 10 km apart. Contemporaneous fluviatile lithologies in West Suðuroy are composed of reworked palagonitised tephra, basalt lava clasts and plant material.

The aim of archaeology is the reconstruction of past cultures and the processes behind cultures. Conclusive evidence of cultural contacts between distinct groups of peoples is of great importance. It has long been realised that the study of the raw materials utilised for artifacts that were then moved far from their place of origin is vital in identifying these contacts and this study is concerned with the investigation of one such material - steatite. Steatite is a soft talcose rock that is easily carved even with stone, bone or metal tools. It also has a low coefficient of thermal expansion. These physical properties have resulted in steatite being used as a raw material for the production of many domestic and decorative items throughout the world from prehistoric times until the present. However, the geological formation process has only occurred in a limited number of locations, and hence steatite sources have a relatively restricted geographical distribution. Thus steatite can be seen to fulfil a number of the basic requirements for provenancing, namely limited geographical distribution and extensive utilisation in the past. As a lithic material the physical production techniques do not affect the physical and chemical nature of the material, which may be a considerable problem with characterisation of other archaeological material, eg. ceramics, metal and glass. Thus by characterisation of source material, steatite artifacts of unknown provenance may be compared and their ultimate origin established. However, the formation of steatite is a complex process that often results in a source body that is inhomogeneous, making simple characterisation techniques inadequate. This study seeks to establish differences between source regions and between individual quarries. If a unique pattern in measurable properties can be established, by comparing artifacts to sources, their origin may be established.

The Boulder Conglomerate is the Lower Carboniferous sedimentary allochthon deposited in the second order half graben created by major listric normal faults in the Navan area. The base of the Boulder Conglomerate comprises erosive-based, highly immature rock avalanches which are interbedded with hemipelagic limestone. Sulphide mineralisation in the autochthon, the Pale Beds Ore, is truncated by the fault-generated unconformity and is reworked as clasts and matrix into the basal Boulder Conglomerate. Matrix-deficient breccia beds deposited on the unconformity possess mineralisation as cement to interclast porosity. This cement is contiguous with replacement and fracture-cementing mineralisation in limestone strata beneath the unconformity. Mineralisation associated within the interbeds to the Boulder Conglomerate occurs as early diagenetic concretions and as stratiform replacement. The 34S of these sulphides ranges from -21‰ to +1‰. The rock avalanches are overlain by clast-bearing carbonate mud strata. The carbonate mud is replaced by pyrite and paragenetically later sphalerite and galena. The isotopic range of 34S for pyrite (-32‰ to -35‰) is distinct from that of the zinc and lead sulphides (-18‰ to +6‰). The uppermost Boulder Conglomerate is characterised by slumped and brecciated mineralisation which is dominated by pyrite. The 34S values of the in situ and reworked mineralisation range from -40‰ to -23‰. The Thinly Bedded Unit overlies the Boulder Conglomerate and comprises interlayered shales and calcarenite and laterally impersistent, erosive-based, graded bioclastic and oolitic microbeccias. Mineralisation occurs as selective replacement to the microbreccia and as stratiform sphalerite and pyrite mud. The latter occur in-situ as laminae and as channelised debris flows. The reworked sulphide mud supports plant fragments which exhibit exceptional preservation by pyrite, sphalerite and galena. The 34S of the laminated and reworked sulphides ranges from -37‰ to -41‰. (DXN008,313)

This study investigates the nodular and stratified carbonate beds 1n the Ballagan Formation, in the Western Midland Valley of Scotland. The Ballagan Formation, which also includes lutltes and quartz arenites, lies stratigraphically between the Upper Old Red Sandstone end the Spout of Ballagan Sandstone: it constitutes the lower-most part of the Calciferous Sandstone Measures. Microscopic examination of thin sections showed that the carbonates comprise mainly three microfacies which are subdivided on the basis of fabric and crystal-size. Microfacies A is the finest-grained and from it the other two have diagenetically evolved; through neomorphism (Microfacies B), and metasomatism and segregation (Microfacies C). Microfacies B has resulted from multiple neomorphic stages as indicated by crystal-size variation. As a, .result of neomorphism, clay has concentrated In .the intercrystalline boundaries, leaving the new crystals slightly clearer than their precursors. Microfacies C has developed in two ways: (1) metasomatism and (2) segregation. Calcitization of dolomitic beds and segregatIon of calcite in an original argillaceous sediment, both produced Microfacies C. The controlling factors over these processes are unknown. Shrinkage cracks, cavity-cement, and veinlets are common features in both stratified and nodular carbonates. Poorly preserved laminations are uncommon in the untreated rock specimen, but are common in thin section. Whilst it is difficult to prove an algal origin for these structures, they morphologically resemble algal laminations. Calculation of mineral proportions from chemical analyses by X-ray fluorescence show that c 86% of the carbonate beds contain more than 50% of the mineral dolomite, therefore, they are generally dolomites by definition, with minor limestone occurrences. Terrigeneous material content is composed mainly of clay minerals; illite, chlorite, and montmorillonite with common quartz. Gypsum is a minor lithology in the rock assemblages. Electron microprobe analysis has shown that crystals of both Microfacies A and B are composed mainly of dolomite, the crystals of the first contain more clay than those of the latter. Crystals of Microfacies C are composed of calcite. Probing of veinlets confirmed a wide range of mineral compositions. From a consideration of the fineness, bed-thickness, structures, faunas, composition, rock-association and lateral facies relationships, these beds are thought to have formed in a lagoonal environment. On the seaward the lagoon was probably bounded by sand bars; on the landward by caliche pavements and alluvium. The best analogous environment is seen in the Coorong, 5. Australia, where fine dolomitic beds are laid down during the wet season and desiccated during the dry.

An experimental analysis has been conducted on the stability of sediment slopes. This has included a study of the geotechnical properties of sediments and the effects of supporting medium and biological activity on avalanching. The thesis is divided into six sections with three appendices. Section 1: Section one describes the geotechnical properties of Ardmore Bay sediments including particle size distribution, and the phase properties of void ratio, porosity, specific gravity, dry density and bulk density. Section 2: Experiments were conducted on the effects of orientation and shape of the container, volume of sediment, and particle size, on angles of avalanche and repose. Section 3 and 4: Experiments were conducted on the effects of air, water, 50% glycerol. 100% glycerol and alginic acid (low viscosity) on angles of avalanche and angles of repose at successive intervals of time (termed setting time). Section 5: The objectives of the biological experiment were to quantify the effects of biological activity on avalanching. Section 6: The objectives of the Mytilus edulis experiment were to quantify the production of byssus threads in relation to sediment stability. The results of the experiments reported in sections one to six are discussed in relation to mechanisms controlling slope stability in terrestrial and aquatic environments. They are also considered with reference to environmentally friendly methods of stabilising slopes now under active investigation by civil engineers. Topics covered include geotechnical properties, sediment phase relations, fluid viscosity, factors of safety, duration of avalanche and biological activity. I have also discussed slope failure mechanisms, and parallel between engineering and biological stabilisation of slopes. The appendices include geotechnical details of the sediment properties and phase relationships of sediments, sediment permeability, and sediment shear strength. I have also included details of factors of safety and stability analysis of slopes, treated from a civil engineering point of view.