Sulphide-bearing quartz veins occur within the Devonian sediments near Allihies, in the western part of the Beara peninsula, Co. Cork. A local facies change trends east-northeast, coincident in part with a major fault line. Folding and fracturing are different in the sandstone group to the north and the slate group in the south, since these processes are functions of lithology and the thickness of the beds comprising that lithology. The major fold trends west-south-west, hut smaller folds diverge from this trend, and may he conoidal in geometry. Three phases of jointing are proposed, hut emphasis is placed on the early-formed systematic joints which trend east- south-east. The cross-joints between these are occupied by quartz veins, so that Z-shaped bends occur. The main ore- shoots lie in these deflections. Isofracture maps show that these occur in low density areas within hands of high density fracturing. It is proposed that the major quartz veins were introduced before the folds were tightened up, so that deformation of the veins seen in the field and in thin section was the result of this folding phase. The mineralogy of the veins is discussed in length because of the recognition of molybdenite and mariposite. A number of parageneses is proposed, so that the conventional paragenetic sequence shows overlap in the order of deposition of most of the minerals, which include chalcopyrite, bornite, chalcocite, tetrahedrite, pyrite and specularite. Secondary minerals are also described. Exsolution lamellae of bornite in chalcopyrite and vice versa are seen. Propylitic and sericitic alteration haloes occur around most of the ore-hearing veins. Isopach maps are constructed of the thicknesses of these zones related to the thickness of the veins and lodes. Quantitative studies by X-ray diffractometry involved the preparation of standard calibration graphs for quartz, albite, muscovite, chlorite and dolomite, and results are presented. Similar coloured rocks to those adjacent to the lodes occur on a regional scale. Mineralogical comparisons are drawn between these and unmetamorphosed red beds elsewhere. Trace element analyses show a greater distinction between these beds. The origin of the ore bodies is discussed in the light of the evidence presented. If the quartz and metals come from an unseen deeper source, the source rocks must be acid igneous rocks to account for the molybdenite, unless the ore solutions only use the same channelways as the igneous rocks, and rise from the mantle. If they are derived by lateral secretion from the country rocks, movement of the appropriate solutions must have occurred in late diagenesis or early metamorphism when silica was released by the formation of chlorite from other clay minerals.

Condensed beds in the Jurassic of northen Europe are usually characterized by limonite eoliths in a matrix of limestone, marl, or clay. Several of these beds have been studied in this country, particularly those in S.W, England; namely the Inferior Oolite and the Twinhoe Ironshot, (Upper Bathonian). The aim of this investigation was to determine the depositional environment of this facies. It is concluded that these ironshot limestones were deposited in very shallow water conditions, in areas of reduced sedimentation and reworking. In the case of the Inferior Oolite, areas of extreme condensation are separated by areas of less condensed deposits, suggesting the existence of several topographic highs on the sea floor on which the thinnest beds were laid down. Prom borehole data the Inferior Oolite of Dorset and Somerset has been found to lie on a wide shelf, on the western side of a large basin covering southern England. The Twinhoe Beds are considered to have been deposited in a transitional area, between the Fullers Earth Clay facies and the Great Oolite Limestone shelf facies; the Twinhoe Ironshot being formed during a period of reduced sedimentation. Both the Inferior Oolite and the Twinhoe Ironshot contain limonite ooliths, and these have been studied in order to decide whether the- ooliths were once chamosite. This was done means of x-ray diffraction and by electron microprobe analysis of individual ooliths and concretions. The results suggest that the limonite is a primary precipitate, which in the Middle Inferior Oolite has been found to pass eastwards into chamosite oolite, and finally into glauconitic limestones. The origin of the large limonitic conretions frequently found in condensed beds was also studied. It is considered that these are large oncolites on which limonite was precipitated, possibly due to selective adsorption by the algae themselves.

This thesis examines the petrology, geochemistry, and palaeoecology of the west Sicilian Jurassic deposits and, where possible, compares them to similar facies elsewhere in the Alpine-Mediterranean region. The Liassic platform carbonates form the greatest part of the west Sicilian Jurassic in terms of thickness these are a series of white limestones and dolomites whose shallow-water origin is suggested by the presence of such structures as Stromatactis, birdseyes, and shrinkage cracks - and the component lithologies which include pelletal, oolitic and stromatolitic facies. The modern Bahamian pattern of sedimentation compares well with the reconstructed depositional environment of these rocks. Crinoidal limestones, which cap the Liassic platform carbonates, usually occur as discontinuous lenses, and these are interpreted as sand-waves deposited on oceanic seamounts - seamounts which were formed after the carbonate platform had disintegrated during the Lias. The Toarcian iron pisolites, which may also cap the white Liassic limestones, are considered to result from volcanic emanations that accompanied this disintegration. Fossil manganese nodules, which occur in condensed sequences of Middle Jurassic age, have been subject to detailed investigation, and these ancient concretions are comparable in their structure, mineralogy and geochemistry to Recent oceanic iron-manganese accumulations. The condensed sequences themselves - like the crinoidal calc-arenites and the iron pisolites - are interpreted as seamount deposits formed as the presence of stromatolites, boring algae and herbivorous gastropods suggests, in shallow photic zones. Seamount evolution in the Upper Jurassic followed two patterns: the seamounts either sank with the consequent formation of more basinal deposits such as red nodular limestones and radiolarites, or with possible uplift, were the site of more massive carbonate production, with the formation of oolitic and pelletal deposits. Finally, in the Tithonian and extending into the Neocomian, a more uniformly basinal coccolith ooze covered much of the area.

The suggestion that a re-study of the Brachiopoda of the Oolite Marl was long overdue was made by the late Dr. Helen Muir-Wood because, although the extensive collections of Buckman, Richardson, Upton and Walker during the period 1895-1933 proved a diverse brachiopod fauna in the Oolite Marl, the deposit had subsequently received scant attention. Moore (1855, 1861) had described micromorphic species from the Inferior Oolite of Dundry but no parallel investigations were undertaken in the mid-Cotswolds. The apparent recent lack of interest seems strange as immature zeilleriids were certainly recognised by Richardson (1929) in Westington Hill Quarry and ontogenetic stages of zeilleriid genera have been sought for a number of years. In fact, bulk samples of the marl from this locality have yielded such a rich fauna of micromorphic and juvenile brachiopods that the current research has necessarily been restricted to micromorphs and to ontogenetic studies involving the juvenile zeilleriids. An obvious preliminary course of action was to attempt to correlate juveniles of a species with their respective adults. During these investigations it was noticed that the secondary shell mosaic of some specimens was often very well preserved. In the light of Williams' very important contribution to microstructure studies, first with the aid of the transmission electron microscope and subsequently with the aid of the scanning electron microscope, it was decided to obtain as much new microstructural data from the material as possible, in addition to ontogenetic, morphological and systematic studies. The species recognised have been studied separately and the sections are listed below together with the various aspects investigated. 1. Moorellina granulosa (Moore) A. Extraction. Brachial valve morphology. Ontogeny. P.4 B. Punctation. p.27 C. Growth. Microstructure. Palaeoecology. Affinities. p.36 2. Zellania davidsoni (Moore) p.76 Morphology. Microstructure. Palaeoecology. Affinity. 3. Nannirhynchia longirostra sp. nov. p.101 Systematics. Microstructure. Ontogeny. 4. Zeilleria leckenbyi (Davidson ex Walker Ms) p.112 Collection. Nomenclatural problems. Loop development. Loop function. Inter-relationships of Mesozoic long-looped Terebratulida. 5. Summary of Conclusions. p.149.

The structural geology of the South Pennine Orefield is shown to be composed of an interference pattern of folds related in part to basement features. Folds are shown to have developed with varying trends during and after the deposition of the Carboniferous limestone. It is concluded that some of the faulting, normal and reversed, is genetically related to folding. Columnar calcite is shown to be in many cases earlier than fluorite in the vein-faults and is related, to early phases of movement, whilst fluorite relates to later lateral movements on the same vein-faults. The distribution of fluorspar deposits is documented and is related to the occurrence of open structures at the time of mineralisation. The flow of solutions into the preferentially mineralised anticlines is thought to be controlled by differential pressure release of solutions up through the thin shale cover to the overlying Permo-Triassic unconformity. Some of the major potential fluorite deposits are described in detail and it is concluded that there is sufficient potential to Justify an exploration programme with a view to supplying a second flotation plant in the area. The termsore as used in this thesis is potential ore in the generally accepted senzse of the term. the terms possible ore, probable oreand ore reserves are similarly used to refer to degrees of potentiality and are not used in the normal sense of the terms.

Samples from the Neogene and Recent of Sabah, Malaysia, have yielded 43 cladocopine, platycopine and podocopine ostracod genera which are recorded and variously described. The genera Polycope. Cytherelloidea and Atjehella are described in detail and contain a total of 27 new species. Polycope is recorded from this part of the world for the first time. Newly discovered morphological structures suggest that shell ornament may be a valuable aid (to soft parts) in the taxonomy of the genus. The functional significance of many ornamental features of the shell is probably as strengthening devices. Morphology of the marginal pore canals is particularly useful in distinguishing the originally monotypic Atjehella. The existing view, based on foraminifera (Whittaker Hodgkinson, 1979), that the Pliocene Togopi Formation of Sabah was deposited in shallow marine conditions (inner shelf to littoral) is substantiated by its ostracod fauna. At specific level the ostracod assemblages of the Pliocene Togopi Formation and Recent of Darvel Bay, Sabah are new; a comparison of the ostracod fauna of Sabah to known ostracod faunas from the Indian Ocean and adjacent areas (e.g. Western Australia, Java-Sumatra, Burma, Western India and the Persian Gulf) reveals a pattern of discrete faunal areas within a broadly defined Indo-Pacific faunal province.

The Archaean Hopedale Block, in the southern Nain Province of Labrador, Canada, is host to three generations of mafic intrusions of Proterozoic age; the 2.2 Ga Kikkertavak, the 1.6 Ga Kokkorvik and the 1.3 Ga Harp dyke swarms. Also present are two ultrabasic dyke types: firstly pyroxenites interpreted as coeval with the Kikkertavak swarm, and secondly 'high titanium dykes' with opaque-rich compositions of uncertain age. Many Kikkertavak (and Harp) intrusions show highly differentiated phyric textures attributed to rhythmic changes in flow conditions during solidification. Modelling of intradyke geochemical variation shows this can be largely correlated with phenocryst differentiation processes. Other textures indicate more extreme flow variations associated with composite intrusion. Analysis of Kikkertavak dyke morphologies and measurements of magma palaeo-flow directions using anisotropy of magnetic susceptibility suggests that the crack propagation direction during dyke emplacement may be decoupled from the preserved flow direction. However similar measurements on the Kokkorvik sheets suggests that decoupling does not occur in shallow-angle intrusions. Approaching the southern boundary of the Hopedale Block, Kikkertavak dykes show increasing tectonic, petrographic and geochemical alteration. The principle effects are mobile element depletion and redistribution, notably on the dyke margins. Fractional crystallisation, crustal contamination and partial melting processes alone are inadequate at explaining primary geochemical variation in both Kikkertavak and Harp swarms. Instead variation occurs mainly due to the melting of heterogeneous mantle sources. The iron-rich compositions of many Kikkertavak dykes is postulated to result from the underplating into the subcontinental mantle during subduction of mafic ocean plateau material. The geochemical signature of many Harp dykes may result from mixing with similar iron-rich mantle sources with alkaline partial melts added to the continental lithosphere. The geochemistry and emplacement style of other Proterozoic dyke swarms suggest that the mafic underplating model may be more generally applicable.

The Ontario-New York-New England seismic refraction/wide-angle reflection profile was acquired to investigate the deep structural interrelationships between the southeastern Grenville province and the western New England Appalachians. The Grenville province is characterized by 45 km thick crust, with an average crustal seismic velocity of 6.6 km/s and a Poisson's ratio of 0.28+0.01. In the mid-crust a laminated dome-like body is inferred to be composed of mafic cumulate sills on the basis of its high velocity (7.1 km/s) and Poisson's ratio (0.27). The lower crust is characterized by a velocity of 7.0 km/s which suggests a strongly mafic composition such as garnet pyroxene granulite. The Moho is a variable feature, characterized by en-echelon reflections suggestive of compositional interlayering. An anomalous mantle layer with a velocity of 8.6 km/s is proposed to represent an eclogized basaltic layer added to the lithosphere during Grenvillian orogenesis. The boundary between the Grenvillian craton and the western New England Appalachians is marked by an eastward dipping ramp structure which penetrates to a depth of 25 km where it soles out above a transitional mid-lower crustal interface. The New England Appalachians are characterized by an average crustal velocity of 6.4 km/s and a sharply reflective Moho delineating crustal thinning from 41 km to 37 km towards the Atlantic margin. The lower crustal velocity is 6.8 km/s, with a Poisson's ratio of 0.26+0.01. In contrast to the Grenvillian craton the seismic properties of the Appalachian lower crust are consistent with an intermediate composition interlaced with mafic sills related to extensional underplating and intrusion during the rifting of the Atlantic Ocean.

No description available.

The Tertiary upper Eocene-lower Oligocene Gres d'Annot Formation of southeast France essentially is a sand-rich deep-marine turbidite system deposited in a foreland basin with a structurally complex basin-floor topography, where local basinal highs exceeded 400 m over 8 km. Overall, the Gres d'Annot Formation lacks features typical of submarine fans. Deposition of turbidite sandstones and other sediment gravity flow deposits first occurred within basinal topographic lows as a passive fill which progressively buried these features. Within the southern part of the Gres d'Annot Formation outcrops two separate basin-floor systems are identified on the basis of palaeocurrent dispersal patterns and sandstone onlaps against the basin floor topography. These two systems are the eastern basin-floor system, and the western basin-floor system. The eastern basin-floor system includes the Gres d'Annot Formation outcrops from Peira Cava, Contes and Menton. The oldest part of the sandstone succession in the eastern system is located at Peira Cava where deposition took place at the base of a local submarine slope as relatively sand-rich deposits which tend to shale out into the more distal parts of the basin. The sandstone succession in the Contes and Menton areas show an upsection change from amalgamated and non-amalgamated sandstone packets to essentially amalgamated sandstones. The western basin-floor system includes the St Antonin, Entrevaux, Annot and Grand Coyer outcrops of the Gres d'Annot Fonnation. The St Antonin section comprises three members, each showing an upsection change from thin-bedded to thick bedded turbidites to debris-flow conglomerates, to thin bedded sandstones interpreted as distal shelf/upper-slope storm deposits. The Entrevaux succession shows an upsection change from thin-bedded fine-grained to thicker bedded and coarser grained turbidites. The Annot sandstone succession shows an upsection change from essentially non-amalgamated sandstones to amalgamated sandstone packets and interbedded thin-bedded relatively fine-grained turbidites. The Grand Coyer succession comprises amalgamated turbidite sandstone packets with interbedded sandstone and mudstone packets with small-scale channel development within some of the sandstone/mudstone packets. The western basin-floor system is interpreted as an overall progradation and aggradation of a sand-rich submarine ramp/delta slope into the deeper parts of the western basin floor system. Comparisons of the Gres d'Annot Formation with the deep-marine sandstone reservoirs of the Palaeogene of the northern North Sea, show a similarity of confinement of sandstones and sandstone lobes and may provide a useful comparative system.