The most important Greek perlite deposits crop out on the islands of Milos (Provatas and Trachilas areas), Kimolos, and Kos, Aegean Sea, which are currently under exploitation. More than 200 specimens of raw perlite were collected from these perlite deposits and were subjected to physical, chemical, petrographic and expansion tests. The perlite deposits have been formed by a phreatomagmatic eruption, which is the last event of volcanic activity on the islands. Most of the deposits comprise the sand, ash, and perlitic fragments' formation, the perlitic lahar, the perlite beds, and the perlitic dome. The first formation is the precursor of the eruption, and is followed by the perlitic lahar, which is result of lava fragmentation, and the perlite beds, which are slow-cooled lavas. The perlitic dome penetrates into the perlitic succession. Vesiculation has taken place in the perlite beds, producing the pumiceous textures of perlite. Dacite fragments are found in the perlitic lahar, as well. Perlite consists of more than 70% of high silica and alkalies glass. Phenocrysts of quartz, feldspar (mainly plagioclase of oligoclase composition), biotite, opaque minerals (magnetite, ilmenite) and apatite are also present. Various types of perlite, rich in quartz, feldspar, tridimite, and cristobalite, were identified. Two main modes of water are found in perlite. Differences in chemical composition of perlites indicate four individual parent magma sources. The main chemical variation is present in alkalis and Ba, Sr, Rb, and the R.E.E. The Eu anomaly is a common characteristic for the studied perlites. The relationship between glass and perlite composition is given. The specific gravity of Greek perlites ranges between 1.50 and 3.00 gr/cm3, the p.H. between 6.5 and 8.5, the surface area is around 3.00 m2/gr. All the studied perlites indicate good expansibility, obtaining low loose bulk density values (20-240 kgr/m3), low percent of nonexpansibles (1-7%), large particle size, low compaction resistance, high water (15-35%) and oil (400-2200cc/100gr) absorption, and surface area values (6-13 m2/gr). The expanded perlite is chemical inert. A new phase rich in Cr and Fe, a pyroxene, and cristobalite are determined in the expanded product. Four different stages in the expansion process are determined by the scanning electron microscope. The phenocryst proportion and grain size contribute to the expansion results. On the other hand, the chemical and the mineral composition does not affect the expansibility of perlite, perhaps because the range of composition is small. The studied perlite is of good quality and is therefore suitable for filter aid, concrete and plaster aggregate, loose fill insulation, cryogenic, horticulture, animal feed, fire protection, and thermal insulation purposes.

The Karak mudstone, cropping out in the vicinity of Karak town, NW Pakistan, is contained within an Eocene evaporitic sequence deposited in the rapidly sinking Kohat foreland basin. It was buried beneath 5 Km of younger sedimentary rocks. Illite-smectite with 20 to 30% expandable component is the most dominant clay mineral, which has converted from detrital smectite or highly expandable illite-smectite in a diagenetic environment at ~ 100 C. Time does not seem to be have played any significant role in the conversion of smectite layers to illite layers. The A1 and K necessary for the conversion reaction was provided by the breakdown of detrital K-feldspar. Muscovite does not seem to have contributed to this process as suggested by previous studies. Direct lattice images of illite-smectite revealed that conversion of smectite layers to illite layers took place through dissolution of smectite layers and precipitation of illite layers as well as by solid state mechanism. Whole rock chemical analysis suggests that the mudstone is a product of severe weathering of the source area which was mainly composed of acidic rocks. Depleted ions like Ba, Rb, Ca and Mn were probably flushed out from the restricted basin by influx of fresh water. The swelling properties of Karak mudstone are low and even Na activation does not enhance these properties. The smectite layers may already have undergone natural Na activation due to original sea water and pore water hypersalinity. Cation exchange capacity and total surface area values are also low, which suggests this material is unsuitable for most major bentonite related uses. Owing to the higher concentration of Mg and Fe ions in the octahedral site of illite-smectite these clays were easily activated with HCl. Acid activation also increased surface area as measured by BET method. Bleaching performance of activated material measured on rapeseed oil showed optimum bleaching capacity of 90% following treatment with 2N HCl for three hours or 3N HCl for two hours. The maximum bleaching capacity was not associated with maximum surface area. Pilot plant scale tests should be carried out to investigate the potential for industrial applications of this material.

Geographical Information Systems (GIS) are rapidly developing computer systems for managing spatial data. This study used GIS techniques to analyse and visualize exploration geochemical data, to extract spatial information from Landsat images, gravity and aeromagnetic data and to model gold potential using logistic regression, weights of evidence, Dempster-Shafer and fuzzy logic methods. Regional exploration geochemical data from various data sets were represented using the catchment method. Experimental regression analyses for evaluating the influence of Fe-Mn scavenging effect and lithological variations show that zinc is most affected by these factors. The importance of anomalous catchments and dilution effect for zinc was also evaluated using mineralization rating and productivity methods. Soil samples collected in this study suggest that there is no base metal mineralization associated with gold at Whympston area, but limited anomalous haloes around the Loddiswell Mine. Lineaments were extracted from Landsat images using the objective lineament extraction and enhancement method. A shaded relief technique was used to enhance the variations of topographical, gravity and aeromagnetic data. Gravity and aeromagnetic data were also processed using second vertical derivative and reduction to the magnetic pole. Results show structural features possibly related to faults on the processed images and highlight highly elevated magnetic anomalies over the Kingsbridge area suggesting an association with possible unexposed hornblende schist related to the Start Complex. Both descriptive and conceptual models for gold occurrences were constructed, which were then correlated with results from the inductive and deductive modelling methods used. Logistic regression and weights of evidence methods have relatively good correlations with known gold occurrences and highlight the importance of felsite in the area. However, very low weights are related to binary patterns over the areas associated with unexposed gold potentials. Dempster-Shafer and fuzzy logic methods can overcome the shortcomings for incomplete data in data driven methods. These methods allow the inputting of weights (degree of belief and membership grade) from well documented mineral deposit models without any prior knowledge of gold mineralization in the area. The deficiency of deductive methods is that there are sometimes large discrepancies between the predicted favourable areas and known gold occurrences.

The microcrystalline vitric mass of Pliocene volcanic tuffs of Santorini and Polyegos islands, in the South Aegean Volcanic Arc, has been replaced by authigenic zeolites and clays. The Santorini tuffs are dominated by heulandite type 2 and 3, the classification based on thermal tests, illite/smectite phases, and mordenite, opal-CT, cristobalite, feldspar, quartz and amphibole. The composition of the heulandite minerals can range from (Na2.12K2.56 Ca0.40Mg0.19) (Si29.97A16.08O72) 24H2O and (Na2.60K2.28Ca0.48Mg0.27) (Si29.71 A16.20O72) 24H2O, where Na and K dominate in different proportions, to more calcic members (Na1.56K1.26Ca1.19Mg0.58) (Si29.35A16.71 O72) 24H2O where Ca and Mg dominate. Microprobe analyses classify the heulandites as type 3. Heulandite classification, then, requires the combined use of thermal tests and microprobe analyses. The heulandites show a platy crystal habit and they form, by the mean of dissolution, pseudomorphs after the inner parts of glass shards. The tuffs from the north part of Polyegos island are dominated by mordenite and illite, rarely illite/smectite, along with heulandite type 3, opal-CT, kaolinite, quartz and feldspar. The composition of the mordenite includes, as well as the typical Na-Ca members, with analyses within the known field of mordenite composition, mordenites with unusual high K values. So the formula can range from a (Ca0.68Mg0.49Na4.05K0.52) (Si41.06Al6.94O96) 24H2O where Na and Ca dominate and the Na/K ratio is 7.79 to (Ca1.20Mg0.20Na2.31K2.39) (Si40.61A17.41O96) 24H2O where the Na/K ratio is 0.97. The mordenites show a fibrous habit and replace the inner part of lapillus pumice fragments. They were probably formed by the circulation of hydrothermal fluids through the volcanic tuffs, followed by the emplacement of rhyolitic lavas in the area. The hydrothermal alteration event led to the formation of numerous baryte and galena veins and flats. The examination of other crystal phases present in Santorini tuffs indicates that not all of the products in the Santorini volcanic suite were the result of the involvement of more fertile asthenosphere, as was believed. Volcanic products, like the tuffs examined, show mineral chemistry similarities with their counterparts from the two ends of the volcanic arc. Therefore, the maximum crustal thinning under the central part of the South Aegean Volcanic Arc, which is responsible for this different source for the generation of magmas in this area of the Arc, had not been completed before the Upper Pliocene, at the very earliest. The examination of geochemistry reveals that the parent materials were dacites to rhyodacites in Santorini and dacites-rhyodacites to trachyandesites-trachytes in Polyegos. The volcanic tuffs from both areas are the product of a fractional crystallisation process with most distinctive evidence found in Polyegos. Santorini shows evidence of magma mixing process also. The traditional cation exchange capacity methods require modification when used with tuffs rich in zeolites regarding the saturation time and the ammonia measurement techniques. Nevertheless, the zeolitic tuffs exhibit excellent cation exchange properties higher than it was expected. Their great ability to combine with lime, in water saturated environments, and act as pozzolanic materials, improves the performance of concrete mixtures. Mixtures which are made by replacing ordinary Portland cement, for calcined zeolitic materials and in various proportions, are able to reach and maintain compressive strength values, higher than standard concrete cubes which are made of 100% Portland cement as the binding agent. Finally, using relatively cheap mineral separation techniques, like dry sieving, fractions rich in zeolite minerals can be easily obtained.

Confined-to-unconfined flow transitions in deep-marine systems occur in areas where either a submarine channel passes into a depositional sheet/lobe or a submarine canyon passes into a submarine channel or basin plain. Transition zones are areas of complex interplay between erosive and depositional processes. Much recent research has concentrated on submarine channels or depositional lobes. This thesis attempts to identify characteristic features and deposits associated with zones of confined-to-unconfined flow transition. GLORIA sidescan data from the Bering Sea is studied here in detail to investigate the role of basin configuration in relation to the development of different styles of transition zone within a modern deep-sea environment. A high-resolution study of the channel-mouth of the Petit Rhone Channel in the NW Mediterranean reveals that channel-mouth areas are candidates for an hydraulic jump to occur (Komar 1971). Breaks-in-slope (up to 3) occur in the mouth of the Petit Rhone Channel and have produced a characteristic channel- mouth erosion facies associated with increased flow turbulence. This study used ancient analogues from the Eocene Hecho Supergroup (Mutti et al. 1989) to make detailed investigations into facies and facies associations in areas of inferred transition from channel-to-lobe and from canyons-to-slope. All but one of the turbidite systems of the Hecho Supergroup exhibit submarine channel development The Arro Sandbody does not exhibit features characteristic of a submarine channel deposit. A detailed study of this system illustrates the importance of structural control on turbidite fan development. Uplift in the shelf region associated with the Arro Sandbody may have produced a break-in-slope in the canyon area which allowed flows to become highly turbulent due to hydraulic jump conditions. Other turbidite systems of the Hecho Supergroup exhibit vertical facies variation from a highly erosive facies at the base of the sections to a more depositional facies higher in the sequences. This temporal facies variation can be attributed to slope degradation processes active contemporaneous with sedimentation acting to reduce slope angle and breaks-in-slope. This inferred change in topographic conditions is thought to have direct relevance to transition zone processes. In conclusion, conceptual frameworks for transition zones have been developed, both for modern deep-marine systems and ancient deep-marine systems. The data collected in this study indicates that young fan systems with irregular sea-floor topography, are more likely to develop erosive facies and faces associations in transition zone areas as the irregular topography can cause turbidity flows to hydraulically jump. More mature systems tend to have a smooth sea-floor topography, and this produces more gradual transition zone facies as flows tend not to hydraulically jump.

An understanding of the way in which electrical currents flow through geological materials enables pertinent problems to be addressed, for example: determination of oil saturation; prediction and monitoring of fluid flow; fracture characterisation; assessment of geological structure in a general sense. The objective of this work is to simulate current flow and electrical resistivity measurements made downhole and at the earth's surface in three dimensions. This enhances interpretation by enabling the geological controls on field measurements of resistivity properties to be assessed. In addition, a basis for a wide range of applications using quantitative analysis of electrical measurements is provided. A finite difference numerical model based on the direct solution of a generalised form of Poisson's equation is developed. Both electric potential and current flow are readily simulated on a rectangular three-dimensional grid. Arbitrary resistivity distributions and electrical anisotropy can be accommodated. The model grid is advantageously analogous to (and therefore supersedes) resistor networks previously built to simulate resistivity logging tools. The model is developed through three applications. The simulation of a novel multi-electrode focused surface array is used to assess and interpret field measurements. The Ocean Drilling Program High Temperature (ODPHT) tool, a new downhole focused resistivity device, is modelled on an adapted cylindrical grid in order to calculate its geometric factors. Finally, a generalised model of a downhole electrical imaging device based on Schlumberger's Formation MicroScanner is created. Current flow is simulated from an array of 5 mm diameter electric buttons that are passively focused into the formation. This is used to generate simulated electrical images. The numerical model is verified by comparison with field data in well-constrained situations. Electrical measurements and current flow patterns have been investigated in three dimensions at a variety of scales. An enhanced understanding of the operation of surface and downhole electrical devices is gained through modelling selected geologically relevant scenarios. Specific benefits are: enhanced fault detection in the case of the surface array; quantitative characterisation of the ODPHT tool in idealised borehole environments; radial fracture characterisation using electrical images, and potential image artefacts due to localised off-hole anomalies.

Tungsten mineralisation lies within the Asian plate to the north-west of Main Karakoram Thrust, which marks the suture zone between the Kohistan complex (Northern Pakistan) and Asian plate. Scheelite has been found mainly in the calc-silicate quartzites and subordinate tourmalinites associated with metapelites at Miniki Gol. This succession is intruded by leucogranites emplaced after the culmination of amphibolite facies metamorphism followed by retrogression. The area has undergone at least two deformational events and scheelite seems to be structurally controlled. Miniki Gol leucogranites are exposed 400 m away from the scheelite mineralisation and tungsten appears to be genetically related to these leucogranites. The chemistry of these leucogranites particularly high levels of Li, Be, W, Sn and Ta fairly coordinate with the specialised granite. The trace element chemistry and the chemical composition of clinozoisite, sphene, amphibole, grossular garnet, biotite, chlorite and scheelite of the calc-silicate rocks indicate a pronounced hydrothermal activity at Miniki Gol. The chemical composition of the tourmaline and spessartine-rich garnet of the tourmalinites is similar to that of tourmaline and spessartine-rich garnet of the leucogranite reflecting a genetic linkage. The occurrence of scheelite-bearing skarn at Miniki Gol further support a genetic relationship between scheelite mineralisation and leucogranite. In addition, the geochemical data of the Miniki Gol tourmalinites have been found similar to that of schist and hence can not be considered as siliceous chemical precipitates. Background level of tungsten is slightly higher than those of the average shale but not anomalous that rules out the possibility of the pre-granitic enrichment of tungsten at the study area. The consistency of the fluid inclusions both within leucogranites and calc-silicate rocks also signify a genetic link between the scheelite mineralisation and the possible post-magmatic hydrothermal fluids. The Miniki Gol W mineralisation has been compared with Cornubian Sn-W deposits. In both the areas tungsten seems to be enriched after the emplacement of granites. The stratiform and stratabound lead-zinc mineralisation is mainly confined to the marble horizon at Besti Gol. The conformability of the sulphide mineralisation with the host marble indicates that these mineralisations have been precipitated in synsedimentary environment.

This thesis documents and analyses the distribution of acritarchs, prasinophyte algae and palynofacies at the basal stratotype of the Ludlow Series (Silurian) at Pitch Coppice Quarry, Ludlow, Shropshire, and the nearby Goggin Road section. Ten new species are erected; Cymatiosphaera lawsonii, Cymatiosphaera multicrista, Cymatiosphaera paucimembrana, Cymatiosphaera triangula, Baltisphaeridium. spinatum, Buedingiisphaeridium reticulum, Glyptosphaera heltaskelta, Gorgonisphaeridium. listen, Leptobrachion digitatum and Pulvinosphaeridium dorningii; 31 new species are described in open nomenclature. The diagnoses of Psenotopus, Psenotopus chondrocheus, Cymatiosphaera octoplana, Dorsennidium europaeum, Dorsennidium rhomboidium, Eupoikilofusa filifera, Evittia robustispinosa, Pulvinosphaeridium oligoprojectum, Schismatosphaeridium rugulosum and Veryhachium trisphaeridium are emended. Six new combinations are proposed; Comasphaeridium brevispinosum, Dorsennidium polygonale, Dorsennidium wenlockianum, Evittia aculeata, Evittia almarada, Gorgonisphaeridium citrinum. The ranges of Buedingiisphaeridium pyramidale and Neoveryhachium mayhillense are extended, producing an overlap between biozones W3 and LI of Doming (1981a). Biozone L2 may, possibly, be recognised by G. listeri 78.4m above the series boundary (Middle Elton Formation). Zone 6 (Gorstian-Ludfordian stages) of Martin (1989) is identified by Percultisphaera stiphrospinata (+83.5m, Middle Elton Formation). Potentially important taxa for future biostratigraphic research are highlighted and these may be used to refine the existing biostratigraphic schemes. The palynofacies analysis undertaken identifies a Wenlock-Ludlow series boundary event correlating with the delta13C event of Corfield et al. (1992). Transgression induced reworking, concentrating 12C rich organic matter, is proposed as the cause. Between Pitch Coppice and Goggin Road this event is diachronous. Individual taxa, which occur through the section in ~80% of samples, are grouped by cluster analysis. These groups, and the distribution of rarer taxa, are related to the palynofacies analysis, and a series of events are proposed (fluctuations in sea-level, marine/terrestrial productivity, sedimentation rates, palaeoenvironment, palaeoceanography) These events are compared to eustatic and climatic/oceanic models.

A rigorous understanding of conodont element morphology is fundamental to virtually every aspect of conodont research, yet the complexity of morphological variation within elements presents a challenge for qualitative approaches. To address this problem, a suite of new morphometric protocols has been developed and applied to two conodont taxa. Analysis of the conodont Ozarkodina excavata has enabled development of a new quantitative methodology to objectively discriminate between morphologically similar elements occupying different positions within the conodont skeleton. The methodology differentiated elements with a success rate comparing favourably to expert discrimination, and has application not only in identifying homology in collections of isolated elements, but also in taxonomy. The hypothesis that '0.' excavata is monospecific has also been tested, and the discovery of significant morphological discontinuities between spatiotemporally separated populations strongly suggests that multiple species are currently accommodated within this taxon. The protocols also have potential to permit repeated and objective identification of biostratigraphically useful morphologies. A natural population of lO.' excavata has been examined, elucidating population structure, survivorship and element and apparatus growth within this taxon at a level of detail exceptional even for conodont studies. Evolutionary and taxonomic hypotheses have been tested in the conodont genus Pterospathodus, using a long, densely and evenly sampled stratigraphic sequence. This has revealed few discontinuities within measured variables through time, highlighting the difficulties of objective taxonomic division of an anagenetic continuum. Apparent directional evolutionary trends are partially confirmed, but analysis is hindered by the inability to identify immature elements and separate ontogenetic and evolutionary change. This study has quantified evolutionary rates in conodonts for the first time. The methods and results presented here have the potential to catalyse comprehensive morphometric analysis of conodonts using these widely applicable protocols and refine the existing qualitative framework around which our understanding of conodont morphology is currently based.

A geochemical study of the Eybek Dag igneous mass of north-west Turkey and its mineralized surroundings is described. The results of chemical analyses of rocks, soils and stream sediments of the are are presented, together with computerised data processing and statistical analyses of this information. Colorimetric, spectrometric, x-ray fluoresence and flame-photometric methods of analysis were employed for rocks but only colorimetric methods were used for the soils and stream sediments. The wall-rocks of four ore-deposits, as well as some dyke material, were also analysed by the spectrometric method. The analytical data are presented as population distribution maps, each population being separated by the probability paper technique. The data are also evaluated by cluster and principal components analyses. Instead of the conventional graphical presentation, the Q-mode results of the principal components analysis are clustered using a distance matrix based on the vector scores. Using the observed primary and secondary dispersion patterns, significant geochemical differences between the two main batholiths of the igneous mass are shown, and the relationships between such patterns and known mineralization are defined. The use of these patterns in investigating the mechanisms of ore deposition is also investigated, and the application of the various geochemical techniques described (particularly rock chemistry) to mineral exploration is discussed.