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The Bulancak Cu-Pb-Zn sulphide veins are the best representatives of their type among the varied deposits of the Eastern Pontus Ore Province. Kuroko, vein, stockvjork, prophyry-type copper, skarn-type iron and manganese deposits with subduction related volcanicity have been described from this province by various authors. Petrographic study of the Country rocks, despite their hydrothermal alteration, shows that they are mainly calc-alkaline. Volcanicity took place from Upper (possibly Lower) Cretaceous to Miocene as indicated by intrusives dated at 25 million years. Ore microscopy studies have proved the first occurrence (in Turkey) of Betekhtinite (Cu, Fe)(_21)Pb(_2)S(_15) and Aikinite (PbCuBiS(_3))-Bismithinitre(Bi(_2)S(_3) solid solution minerals. Idaite is reported for the first time from the study area. Field and Laboratory work have shown the structural control of Mn, Fe and Cd distribution in sphalerites. Mn follows a NW-SE trending zone from Kusdere to Kasyatak whereas Fc-Cd distribution follows a SW-NE trending zone between Kovalik Sr. and Kuloglu along Kűçűkgűre Dere (stream), reflecting the dependance on the two major fracture systems in the area. Data based on a study of more than 2500 primary and secondary fluid inclusions in transparent ore and ganque minerals is given, including measurements on the temperature, pressure, density and salinity. The inclusions were moderately saline, salinity varying within the range 13.2 equivalent wf.% NaCl to almost fresh water indicated by a 3 density change from 0.74gm/cm(^3) in the early vein stage to 0.98 at the end of the base metal sulphide stage. These variations way reflect the mixture of deeply circulating meteoric waters with rising, saline, hydrothermal fluids. Homogenization temperatures ranged from ca. 340 C to 80 C. Inclusions in neighbouring early formed quart2 and sphalerite minerals from the same vein show a temperature rise from ca. 230 to 330 C in the early vein stage, and eventually boiling conditions were reached. At a later stage the fluids cooled from 330 C to ca. 80 C. in the base metal stage. The highest temperatures were obtained from the Tekmezar Group Veins, in comparison to the DarikBy Group Veins, indicating a horizontal temperature zoning in which the Bi-content of the aikinitebismuthinite solid solution minerals increases from West (Saridiken Dere) to east (Kornali Dere). Data obtained from isotherms indicates that the ore-bearing fluids rose along NW-SE trending faults. This explains the concentration of veins around the Selmanoglu, Gonurca Dere, and Uzllinltik Dere Faults. Simple cooling of the solutions, pressure fluctuations, density and replacement processes played major roles in the formation of these veins. Fluid inclusion studies combined with geological data, are considered to be useful parameters in mineral exploration to pinpoint the richest part of an orebody. Metal transport and the thermal history of vein mineralisation are discussed in the light of fluid inclusion data.

The blue river ultramafic body is one of many “alpine” peridotites intruded into the Sylvester volcanic series in Northern British Columbia. The primary duniteharzburgite assemblage consists of olivine (FO (_89) – FO (_95)) enstatite (En (_90) – En (_92)), and spinel. The spinel chemistry is variable, dunite spinels give Crx100/ (Cr+Al) ratio of 58 and above, and peridotite spinels are invariably below this figure. The assemblage, which was evidently intruded hot as it has formed a “hornblende hornfels” facies amphibolite aureole, is inferred to have equilibrated with volcanic magma, present in the form of bodies gabbro. The body has been truncated by the Cassiar batholith. Metamorphism has affected both the primary assemblage, and also an early generation of marginal serpemtinite. Isograds have been established which mark the incoming of metamorphic olivine, tremolite, olivine with talc, and enstatite. Metamorphic olivine porphyroblasts in the outer aureole of the batholith are zoned. They have an inner turbid core enriched in Fe and Mn, and a clear outer margin enriched in Mg. Ni will enter olivine only in the absence of sulphur. A maximum core to margin range of FO (_85) – FO (_97) we found 4,000m from the contact. Above the olivine with talc isograd the assemblage is influenced by increased FO (_2). Primary spinels in both peridotite and serpentinite are oxidized. Al substitutes in the serpentine structure to form chlorite, and the spinel absorbs Fe, Mn and Ni. The al content in the chlorite increases towards the batholith contact. Metamorphic olivines are weakly or non zoned, and they reach a composition of Fo (_95). Metamorphic enstatite is similarly Fe depleted at En (_93). The body underwent partial alteration to antigorite during the waning stages of thermal metamorphism, and more pervasive serpentinization on cooling. Euhedral olivine porphyroblasts in a matrix of relict serpentine retain their original outlines, and they undergo volume for volume replacement. The lizardite-chrysotile assemblage contains abundant brucite, which envelopes serpentine pseudomorphs after metamorphic olivine. This is indicative of cation mobility during serperntinization.

The area studied is situated in the North East of Nigeria and consists of a rock complex known as the Older Granites to differentiate it from the granites of the ring - dyke complexes, termed the Younger Granites. The rocks in the district are classified as metasediments, migmatites, Biotite Granite, Biotite Hornblende Granite, Fayalite Quartz Monsonite and Quartz Diorite. In the field the rocks were examined in detail and a geological map of the area constructed. The contant relationships of the members of the OlderGranites are described and results of detailed petrographical examination given. In particular, a study has been made of the microstructures, including perthite and myrmekite; from various considerations the microstructure appear to indicate a metasomatic origin for large microcline crystals found in these rocks. Various lines of evidence for and against both magmatic and metasomatic origins for the Bauchi rocks are examined; the equivocal nature of much of this evidence is stressed. The weight of petrographic and field evidence, backed by the plutonic setting and spatial distribution of the different rocks, is thought to indicate a metasomatic origin for the migmatites, the Biotite Granite and the Biotite Hornblende Granite. The Quartz Diorite and the Fayalite Quartz Monzonite are demonstrated to be related the Charnockite series; they originated by a soaking of the Biotite Granite and the Biotite Hornblende Granite respectively with dilute basic magma or solutions under deep seated conditions. It is suggested that the basic solution could have originated from the basic material displaced in the zones of granite and migmatites. The petrology of the Bauchi rocks is considered in the light of problems relating to granites and charnockites in general. The account includes ten chemical analyses of' rocks from the Bauchi area, as well as optical data on the minerals and numerous modal analyses.

The contamination of mantle-derived magmas by the continental crust is an important process during petrogenesis of volcanic rocks at active continental margins e.g. The Andes. Investigating the evolution of continental arc magmas is, however, hampered by our limited knowledge of, and poor constraints on, the nature of the underlying crustal basement and the mechanisms of crustal anatexis. This thesis reports results from: 1) a whole rock geochemical and in-situ geochronological investigation of a suite of crustal xenoliths from the Bolvian Altiplano, Central Andes; 2) a whole rock geochemical study of the xenoiths’ host lavas and; 3) detailed in-situ geochemical studies of crustal partial melts (quenched to glasses) trapped within their crustal progenitors from Bolivia, NE China and SE Spain. Sampled crustal xenoliths from the Bolivan Altiplano provide a rare insight into the nature of the Central Andean continental basement and reveal lithological and geochemical heterogeneity exists at depth with 87 Sr/86 Sr values extending to 0.7368 which is more radiogenic than any Srisotopic signature exhibited by the recent (< 60 Ma) volcanic record. In-situ U-Pb dating of zircon separates reveal predominant age peaks at 1.7-1.9 Ga, 1.0-1.2 Ga and 495-380 Ma which correspond to periods of supercontinent formation and break-up e.g. construction of Rodinia. Lavas erupted from monogenetic centres on the eastern Bolivian Altiplano show petrographic and geochemical evidence for crustal contamination. The geochemical heterogeneity exhibited by the lavas is, however, difficult to reconcile through simple two component crust-magma interaction models (bulk mixing, AFC and EC-AFC). Instead, contamination is inferred to have involved numerous crustal components. The geochemical signatures observed in lavas from monogenetic centres towards the active Andean arc (between ~18-21o S) are distinct (e.g. lower 87 Sr/86 Sr, higher Sr/Y, higher Ba/Nb at higher Zr/Nb) and may indicate a lower degree of crust-magma interaction, an increase in the contribution from slab-derived fluids and thinner crust arc-wards, the latter which has previously been inferred from geophysical studies. In-situ analysis of anatectic melts reveals that Sr-isotopic disequilibrium between a crustal melt and its source can exist on the sub-millimetre scale. This is understood to reflect the melting of aged minerals with different Rb/Sr (and therefore 87 Sr/86 Sr) more quickly than the isotopic composition can diffusively equilibrate between melt and minerals. Results suggest therefore that crustal anatexis can produce melts which are geochemically heterogeneous both spatially and temporally. This highlights the need for detailed microscopic investigations coupled with petrogenetic modelling in order to develop a more robust characterisation and well-constrained quantification of crustal contamination in open magmatic systems.

In the course of the present study the area has been mapped in detail on the six inch scale and a stratigraphical succession has been suggested. The regional metamorphism has been investigated and found to be of amphibolite facies. Metamorphic zones demarcated in pelitic rocks by staurolite, staurolite + sillimanite, and sillimanite + muscovite, have been recognised and the zonal isograds have been mapped. Two post-kinematic granites were intruded into the metasediments, they are adamellitic in composition and are, together with veral other small granite bodies, related to the Galway Granite. The metasediments have been thermally metamorphosed and zones of thermal metamorphism have been mapped, an inner zone of andalusite hornfels, (hornblende hornfels facies), and an outer zone of spotted schist, (epidote actinolite hornfels facies).Fourteen chemical analyses of the metasedimentary rocks were made with the purpose of investigating the question of metasomatism in the regional and thermal metamorphism, and for comparing the metasediments with unmetamorphosed sedimentary rocks. It has been concluded that metasomatism did not occur during either the regional or thermal metamorphism. Chemically the metasediments compare closely with sediments carried into a shelf sea from an adjacent land mass of moderate or low relief and it is concluded that the metasediments were deposited under similar conditions. Three periods of folding have been recognised: 1. East - West, syn-metamorphic 2. East - West, post-metamorphic 3. North - South, post-metamorphic. The first east-west folding resulted in the formation of recumbent, isoclinal nappes. These were subsequently cross folded about an east-west axis to give the present - Connemara anticline which was then deformed by gentle folding about a north-south axis. A swarm of north-south trending dykes was intruded in association with the granite emplacement, and at the same time the area was fractured by a system of faults striking north west - south east, and north east - south west. The area was finally subjected to sub-aerial erosion and glaciated in Pleistocene times.

The present study is placed in the context of the disastrous Aberfan (Wales) colliery tip failure in 1966, particularly with respect to the singular lack of knowledge regarding the consequences of long-term weathering of coal-bearing strata. Initial breakdown of fresh indurated sediments from underground workings (roof and floor measures) is shown to be a function of a) sedimentary structures b) capillarity (air-breakage) c) expandable mixed-layer 10A clay content. A geographical variation in clay mineralogy implies that breakdown should generally be at a minimum in the Durham, Northumberland and Scottish coalfields. An in situ study of a stratigraphic section containing all rock-types likely to be found in British colliery tips shows that chemical (weathering) processes are very restricted. Pyrite is the only mineral species which has completely broken down within the 8ft-deep weathering zone, over a period of about 10,000 years. Cohesion is the strength parameter most susceptible to in situ degradation and the shear strength parameters of the near-surface materials generally conform with those of jointed and fissured rocks, rather than soils The residual (ultimate) strength of weathered- unweathered Coal Measures sediments is shown to be a function of the ratio quartz: clay minerals. Major temperature-time dependent, mineralogical changes in the superficial zone of the very coaly, 100-year-old Brancepeth colliery tip are not matched by a large fall-off in shear strength. The composite internal friction value is similar to shale-fill dams in Britain; there is no statistically significant strength difference between upper slope (younger) and lower slope (older) samples, which are some 27 per cent higher than the residual spoil strength. Convincing chemical, physical and mechanical data from a 50-year-old tip at Yorkshire Main Colliery show that small changes within the heap are more readily attributable to changing colliery practice, rather than to degradation processes. After initially rapid physical breakdowm, the material has changed little after burial. This study has shown that long-term weathering processes have little influence on the overall stability of colliery spoil.

The Whin Sill complex is briefly reviewed. Theoretical temperatures have been calculated for the metamorphic aureoles in the Teesdale, Rookhope and Ninebanks areas, for comparative purposes with the observed metamorphism. The major and trace element geochemistry of a suite of argillaceous and arenaceous sediments has been examined using R-mode factor analysis. Only one factor is interpreted as a metamorphic feature. This factor is indicative of an increase in Na in beds towards the contact but is of minor volumetric importance accounting for less than 10% of the data variance. The remaining factors can all be interpreted as sedimentary features. X-ray diffraction studies of argillaceous sediments have shown an increase in the crystallinity and a change in the polymorph, from a 1Md to a 2M variety, of illite, towards the contact. Pure limestones have been recrystallized to saccharoidal marbles, which are restricted to the Upper Teesdale region. Dark-coloured limestones are not recrystallized because the carbon present in these sediments prevents grain-boundary movement (Robinson, 1971).Calcareous sediments have been the most susceptible to the metamorphism and a varied calc-silicate mineralogy is developed up to 25 m from the Whin Sill contact. Potassic feldspar, andradite, hedenbergite, prehnite and datolite are recorded for the first time from the contact-rocks of the Whin Sill aureole. The mineralogy developed in the calcareous sediments is indicative of two or possibly three facies and is interpreted as non-equilibrium conditions. The difference in metamorphism between calcareous and non-calcareous sediments is attributed to higher reaction kinetics in the calcareous sediments.Metamorphism by the Whin Sill is virtually non-existent outside the Upper Teesdale region. This is suggested to be due to a magma source in this area, giving rise to anomalous conditions as compared to a simple intrusion into cold country-rocks. The increase of Na in certain beds within 10 m of the contact is not attributed to metasomatic introduction from the Whin Sill. Instead the Na is suggested to have been present as NaCl in hypersaline pore-waters of the sediments, at the time of the Whin Sill intrusion. It is shown that the mineralogy developed in the contact-rocks has largely been the consequence of reaction between illite and the NaCl pore-waters. Haematite has been formed by the release of Pe3+ from the illite structure.Finally it is shown that the unique geology of the Upper Teesdale area, especially the development of saccharoidal marbles, has been of major importance in the sustenance of the rare arctic-alpine flora for which the area is biologically renowned (Johnson, Robinson and Hornung, 1971).

The tertiary to Mid-Quaternary Setberg volcano in western Iceland consists of two centres. The northern, Centre 1 is tholeiitic and defined by cone sheets, a caldera and a gabbro intrusion. The southern, Centre 2 is chemically transitional between a tholeiitic and an alkalic basalt series, and contains a cone sheet swarm, gabbroic ring features and a major granophyric cone sheet. Each centre can be related to a minor magmachamber at a depth of 2-3 km. General hydrothermal alteration around both centres has resulted in aureoles of epidotization and the development of greenstones, containing garnet in the central areas. Late-Quaternary volcanism in the Setberg area has produced an alkalic basalt succession, ranging from alkalic olivine baalts to benmoreites. This activity is related to the E-W Snaefellsnes volcanic zone and its causes are explained in terms of Icelandic plate tectonics. The tholeiitic seies of centre 1, form a differentiated sequence from olivine tholeiites to rhyolites, contaning a Ca-poor pyroxene and augite in the basic and intermediate rocks, and a large compositional interval devoid of olivine. Plagioclase is the sole feldspar phase. The transistional series of Centre 2 is olivine-bearing throughout, with augite and rare phenocrysts of orthopyroxene in the basalts. Two lineages of differentiated rocks of this series are typified either by iron-enrichment (to icelandites) or by alkali enrichment (to rhyodacites and alkalic-rhyolites). The latter contains anorthoclase and potassic oligoclase or sanidine, as well as sodic pyroxene. Rocks of the alkalic series are olivine and pyroxene-bearing, with anorthoclase appearing in the benmoreites, while phlogopite and hornblende have been found in some of the lavas. Apatite occurs as a phenocryst in members of both the transitional and alkalic series. The origin of the transitional basalt magma is discussed according to two hypotheses. Its formation is accounted for by solidification from above in a magma reservoir of great vertical dimensions, leading, to confinement of the magma to depths where orthopyroxene replaces olivine on the liquidus, resulting in a trend towards undersaturation. The chemistry of the Late-Quaternary alkalic basalts of Setberg and Snaefeilsnes is related to magma generation at greater depths than in the case of the tholeiitic basalts of the Icelandic central volcanic zone. The volume, bimodal distribution and diversity of acid and intermediate magmas in Iceland are discussed. The high proportion of acid to basic volcanic rocks in eastern Iceland is contrasted with 3-4% in the rest of the country. Two types of acid centres are identified: centres of Thingmuli type, where tholeiitic basalts are associated with low-alkalic rhyolites; and alkalic centres, containing comendites, quartz- trachytes, alkalic-rhyolites and associated alkalic basalts or transitional basalts. Peralkaline acid rocks are identified and described from Iceland for the first time. Their genesis is discussed and related to fractionation from alkalic-rhyolites and trachytes by the "plagioclase effect". No evidence has been unearthed in this study which contravenes the hypothesis that the Icelandic acid rocks are a product of fractionation from basic magma.

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