The Ringerike area of southern Norway has been re-mapped and the general geology, sedimentology, fossil fauna and flora, and structure of the Silurian and Lower Devonian has been studied and compared with other areas. Special attention has been paid to the abundant primary sedimentary structures and these have been used to interpret the conditions of deposition and the palaeogeography. During the Llandovery, shallow-water conditions gave way to a slightly deeper environment where sediments resembling calcareous flysch were deposited by atypical turbidity currents on an undulating shelf trending a little north of east. Shallowing to a level above wave base resulted in the accumulation of shell banks in the middle Llandovery, followed by lower energy sedimentation of red mudstones, unusual in that they are fully marine: their possible origin is discussed. The highest Llandovery consists of shallow-water nodular limestones: bentonites are common at this horizon. The Wenlock commences with deepening and renewal of turbidity current activity, first with the production of calcareous siltstones, later with increase in bioclastic limestones. Development of small patch reefs follows, and the Wenlock ends with well-bedded limestones. The Ludlow continues shallow. Fully marine carbonate deposition with a rich brachiopod-coral fauna alternates with a peculiar platy carbonate facies with, limited fauna, mainly ostracodal lout with algae and eurypterids: this is prohahly lagoonal. A number of red mud-cracked horizons indicate periodic emergence. Some bentonites are present. There is a rapid hut conformable change from marine Ludlovian to typical red-bed development (the Ringerike Sandstone), hut the crustacean and fish faunas show that these beds should still he considered Ludlovian in age. The higher unfossiliferous red-heds may well extend up into the Lower Devonian. The primary structures, especially crossstratification, show that clastics from the rising Caledonides in the north were heing spread out over a wide alluvial plain.

The Kisingiri volcano of Tertiary age, consists of a pile of lavas and agglomerates 60-70 Km. across underlain by Precambrian basement and early Miocene alkaline silicate and carbonatite intrusions. A pyroxenite-ijolite-urtite complex and a micro-melteigite ring dyke are differentiation products of a melanephelinite magma. An uncompahgrite-turjaite complex formed by the reaction of a layered accumulative peridotite body with its own residual fluids. Micro-ijolite/foyaite intrusions originated by differentiation from melanephelinite magma and metasomatism during intrusion. Emplacement of alkaline silicate complexes resulted in doming of the basement to a height exceeding 900 metres and in fenitisation. Four zones have been distinguished in fenites derived from granodiorite, with variation from fenitised granodiorite with minor replacement of quartz by aegirine-augite to a syenitic fenite with all relic features destroyed by granulation consisting of perthite and aegirine-augite. Leucoadamellite, due to high mechanical strength, was less prone to intense granulation and fenitisation. Sodic amphiboles formed in fenitised diorite. A consequence of fenitisation was metasomatism of ijolite to nepheline syenite by diffusion of silicon ions back, from the country rock. Emplacement of sovites was proceeded by extensive brecciation of the basement with potash feldspathisation at depth, and accompanied by intrusion of potash trachytes, tuffs and agglomerates by fluidisation. A considerable time interval followed before nephelinitic volcanism commenced about 19.6 million years ago. Lacustrine sedimentation occurred on the flanks of the dome. Six hundred metres of lavas (49%) and aggomerates (51%) are preserved. In addition to melanephelinite, nephelinite, and mugearite, melilite- and olivine-bearing lavas are common. Phonolite and alnoite only occur as dykes. No overall differentiation with time is present. The final events were rift faulting and the formation of the Rangwa pyroclastic/carbonatite cauldron.

A 250 sq km area near Tamaby in the Northern Swedish Caledonides has been mapped in detail predominantly at a scale of 1:20000. The rocks have been divided into three tectono-stratigraphic units; the lowest is the Seve-Koli unit, the highest the Laxfjallet unit which shows an affinity to the rocks of both north and south Storfjallet; these are separated in part by the Basement unit, which is tectonically sandwiched in an apparently intermediate position. Detailed stratigraphic, structural and metamorphic studies have been applied to each of these units with particular reference to the geometrical relationship they each bear to one another and also to the nature of the contact between the low- (Koli) and high-grade (Seve) rocks within the Seve-Koli unit. The recognition of a partially preserved ophielite complex in the lower poxt of the low-grade Koli sequence and certain lithofacies considerations have led to the adoption of a sedimentation model controlled predominantly by the development of a marginal back-arc basin in Lower Ordovician times similar to the plate tectonic model proposed by Gale and Roberts (1972) in the Trondheim region. An important early (D1, pre-main schistosity) synclinal repetition of the stratigraphy in the low-grade rocks is followed by a polyphase sequence of deformation (D2-D4) which is similar to that in the higher grade (Seve) rocks and also that in the Laxfjallet unit. The question of the nature of Seve-Koli contact is considered in the light of the metamorphism-deformation relationships throughout the unit, the siting of the different metamorphic isograds, the chemical composition of various garnets and amphiboles and the stratigraphy within the critical transition zone between the two rock suites. Kieft's (1952) interpretation of the petrology of the Laxfjallet rocks is revised and the relationship of these rocks to the tectonically higher Storfjail Nappe is indicated. The lithostratigraphy and tectonic position of the Basement unit, which forms the southernmost part of the Bangfjallet Inlier, is critically reviewed. In particular, the important cataclastic breakdown of the igneous component of the complex from quartz-syenite to flaser gneiss to mylonite is emphasized, whilst its earlier interpretation as a simple window structure is questioned. A detailed study of the geometry of certain F2-F4 minor folds and deformed lineation loci has allowed a qualitative interpretation of the mechanisms of folding to be made. This is combined with the finite strain analysis of a deformed conglomerate marker horizon which has elucidated the relationship between the finite strain ellipsoid and the different deformation phases, particularly the D2 phase of relatively homogeneous strain and the Dif phase of folding. The problem of the pronounced development of F2 fold axes parallel to the major axis of the D2 strain ellipsoid (WI to WNW orientation),and the wider question of the important development of fold axes oblique to the Caledonoid trend are discussed in the light of these results. Finally, preliminary basic v/hole-rock analyses are presented for different metavolcanic rocks within the Seve-Koli unit, and the various gabbro intrusions within the Laxfjallet unit. It is shown, in particular, that the greenstones associated with the serpentinites in the lower part of the Koli sequence are quartz-tholeiitic in composition with subordinate amounts of alkaline-basalt, and possibly show overall affinity to oceanic basalt. Calc-alkaline volcanics are only found slightly higher up the succession,and are pyroclastic and conspicuously more siliceous in character.

The Ringerike Group is a late Silurian red bed succession confined to the Oslo Graben of Norway. At Ringerike (type area) it contains the Sundvollen Formation (500 m) below and the Stubdal Formation (750 m) above. The Kolsas area shows a southerly decrease in thickness; in the Holmestrand area the base is not exposed and the Group consists of the Holmestrand Formation which is, in part, laterally equivalent to the Stubdal Formation. Evidence from vertebrate faunas indicates that the age ranges from lower Ludlovian (Sundvollen Formation) to Downtonian (top of the Holmestrand Formation). Facies analysis indicates that the Sundvollen Formation consists of fine grained sandstones, siltstones and occasional thin calcarenites whereas the Stubdal Formation consists of fine grained sandstones with intra-formational conglomerates. Sedimentary structures and analysis of cyclothems indicate that sedimentation was mostly in fluviatile environments: meandering in the Sundvollen Formation and braided in the Stubdal Formation. The Sandstones of the Sundvollen and Stubdal Formations are similar. They are feldspathic, lithic and quartzose wackes and arenites; those of the Holmestrand Formation are lithic and quartzose wackes and arenites. The main diagenetic events were the authigenesis of quartz and feldspar and the precipitation of calcite cement. The colouration of the red beds is due to hematite grain coatings and matrix which crystallized post-depositionally. Palaeocurrents, sandstone composition and grain size variation suggest a relatively distant source area to the NW in the Caledonian mountains for the Stubdal Formation and a more proximal source on the NE flank of the Oslo Graben for the Holmestrand Formation. Trend surface analysis shows an increase in % quartz (50-70) and % rock fragments (3-7) to the south and a decrease in % feldspar (13-4). The calcarenites in the Sundvollen Formation are interpreted as shallow marine deposits which formed in and at the mouths of tidal channels. Tidal flat deposits and the fine grain size suggest that the Sundvollen Formation formed a coastal alluvial plain with meandering rivers. The Stubdal Formation was deposited by alluvial braided rivers; so was the Holmestrand Formation but the presence of conglomerates shows that they were more powerful than those of the Stubdal Formation.

In northwest Leicestershire and South Derbyshire there are eight inliers of Carboniferous Limestone. The five Eastern Inliers consist mainly of thick to massive bedded dolomite of C.;S.;to age and has been named the Cloud Hill Dolomite Formation. The Formation has been divided into three members: (l) the Massive Bedded Dolomite Member; (2) the Red Bed Member.;(5) the Biohem Member. The three Western Inliers and the topmost beds in the southernmost of the Eastern Inliers consist of thin to thick bedded limestone and dolomitic limestone with interbedded shale and are D2 agej the beds have been named the Ticknall Limestone Formation and divided into two members: (l) the Limestone and Shale Member; (2) the Thick Bedded Limestone and Dolomite Member. The beds in the Eastern Inliers have been strongly dolomitized and are mostly medium to coarsely crystalline dolomite with fossil remains completely destroyed in most cases. The beds in the Western Inliers5 apart from patchy dolomitization of the topmost beds, are largely biomicrite and biomicrudite with interbedded quartz-rich shale. Fossil remains are abundant and well preserved. Dolomitization of the beds in.the Eastern Inliers is thought to have resulted from the invasion of magnesian brines originating from buried sub- Vise'an evaporites; the patchy dolomitization in the Western Inliers probably resulted from Mg∼rich groundwater penetrating the beds from the overlying Trias sic I-Iarl. The Massive Bedded Dolomite Member and the Red Bed Member appear to have been deposited mainly in intertidal conditions, while the Bioherm Member and Ticknall Formation are likely to have been deposited in subtidal conditions. A review of Kent's criteria for distinguishing between gulf and block facies suggests the need for a change in the southwest Widmerpool Gulf boundary. The beds in the eight inliers are highly disturbed structurally, with near vertical strata in the four northernmost Eastern Inliers intersected by normal, reverse, and strike-slip faults, the strike of the beds between the Eastern Inliers offset by sinistral faults, a small anticline through the Western Inliers, and both sets of inliers bounded by post-Carboniferous faulting. The uplift of the beds in the Eastern Inliers is thought to be the result of late Carboniferous to early post-Carboniferous diapirism involving concealed pre-Visean evaporites.

Resting on the Cretaceous pillow lavas of the Troodos Massif, interpreted as an uplifted slice of ridge-generated ocean floor, there is a thick sequence of predominantly pelagic sediments, ranging in age from Campanian to Mid-Tertiary. The earliest pelagic sediments are umbers: iron- and manganese-rich mudstones comparable with the basal sediments of the East Pacific Rise. Umber deposits occur in hollows underlain by thin lava breccias, also by deeper zones of intensely veined and fragmented pillow lavas. Occasional thicker umber deposits are located in elongate fault-controlled depressions: within and above thick lava breccias, restricted to near the south Troodos Arakapas transform fault; and also in depressions inherited from, earlier emplacement of stratiform cupriferous sulphides. Umbers originated in the Campanian due to the waning stages of Troodos ridge volcanism. The sub-umber veining and brecciation was produced by late- stage hydrothermal activity, associated initially with a brief episode of violent volcanism, then with more quiescent discharge of submarine thermal springs from a geothermal system. Large volumes of dilute metalliferous brines were released into open marine waters whereupon umbers were rapidly precipitated. In contrast to umbers, the ochres are ferruginous, but manganese-depleted sediments, which are also associated with massive sulphide orebodies located at depth in the Troodos pillow lavas. Ochres were deposited in less oxidizing seawater, than umbers, within fault-bounded hollows; they formed by a combination of in situ submarine oxidation, erosion of sulphides and sub-adjacent lavas, and, as precipitates from submarine thermal springs. Overall, extrusion of pillow lavas, sulphide emplacement, deposition of umbers and ochres are all interpreted as related events in the evolution of the Troodos ocean ridge. Overlying radiolarites contain well preserved Radiolaria in which silica diagenesis is comparable to that of cherts encountered by the Deep Sea Drilling Project. In wholly autochthonous successions, Maastrichtian chalks follow, and show evidence of solution, indicating deposition close to the carbonate compensation depth. All these sediments are thin (tens of metres). Palaeocene and Lower Eocene chalks are much thicker (to 300 m) but very variable. They contain abundant cherts, some of which replace turbiditic beds of foraminiferal origin. Later chalks, and other sediments record, shallowing waters, a major Miocene emergence, followed by peneplanation, before renewed uplift in the Pleistocene. The uplift history of the Troodos Massif has important implications for emplacement of ocean floor at high crustal levels. In the south-west of Cyprus, a thick sequence of volcano- genic clay and sandstone occurs above the umbers and radio-larites, and beneath allochthonous nappes and melange. These include serpentinite masses, derived from Troodos- type oceanic basement, and the Mamonia rocks; sediments and volcanics of Triassic to Jurassic age, of continental shelf to pelagic facies. In general, ocean floor generation was followed by pelagic, non-calcareous sedimentation; then by intense calc-alkaline volcanism, indicative of an arc-trench gap environment; then by quiet pelagic chalk deposition. The overall tectonic setting points to subduction of Troodos ocean floor in a north-dipping subduction zone until this was finally ended by collision of the Troodos ocean ridge with the southern continental margin of the Turkish Plate. Geotectonic implications are discussed.

Tertiary carbonatites occur along thrust planes at Loe Shilman in Kyber Agency and at Silai Patti in Malakand Agency, NW Pakistan. The Loe Shilman carbonatite sheet complex comprises an amphibole sovite which is intruded by a biotite sovite and an ankeritic dolomite carbonatite. These carbonatites have produced zoned fenites as a result of Na, K and Na+Mg+Fe fenitizing-fluids emanating from the amphibole sovite, biotite sovite and ankeritic dolomite carbonatite respectively. The fenites grading into unfenitized Palaeozoic thinly bedded slates and phyllites. The variation in the whole-rock and mineral chemistries of the fenites correlates with the distances from the carbonatite contact. These gradual variations in chemistry are attributed to the low permeability of the slates and phyllites. A path of fractionation from calcite-rich to dolomite-rich carbonatites can be distinguished, while the final-stages which return to the calcite-rich carbonate phase are recorded only in the carbonatite veins The Silai Patti carbonatite sheet complex comprises a biotite sovite which is intruded by an amphibole sovite. These sovites have induced K-and Na-fenitizations respectively in granite-gneisses, amphibolites, dolerites and quartzites. The chemical variations in the rocks and minerals of the fenites correspond with the degree of intensity of fenitization. The chemistry of amphiboles, micas and pyroxenes which are in equilibrium with the carbonatitic fenitizing fluids are typically magnesio-arfvedsonite, phlogopite and aegirine-augite respectively. It is proposed that the Na-rich carbonatite magmas are derived from the magma produced by liquid immiscibi1ity from phonolite, but the K-rich magma has evolved from the primitive Na-rich carbonatite magma by crystal fractionation.

The Ostracoda of the Great Estuarine Group, Inner Hebrides, Scotland are monographed. These are referred to Order Podocopida, Suborder Podocopina, superfamilies Cytheracea, Cypridacea and Darwinulacea, seven families, five subfamilies, 17 genera (three new) and 41 species (25 new, 11 in open nomenclature). The stratigraphic occurrence of the ostracod species is determined for the Islands of Skye, Eigg and Muck. The major lithostratigraphic subdivisions of the Great Estuarine Group are reflected in the ostracod fauna. The ostracod species are largely endemic to the Hebrides; there are generic level affinities with other British sequences. Ostracod genera are used to interpret the palaeosalinity of deposition of the Duntulm and Kilmaluag formations. In some cases the palaeosalinity of deposition of individual beds is corroborated using C & O stable isotope analyses. Three salinity controlled ostracod assemblages are recognised and are interpreted to have migrated within the Kilmaluag lagoon due to increased freshwater or brackish-marine water input. By comparison with the associated molluscs, conchostracans and algae, four salinity events are detected within the type section of the Kilmaluag Formation. The Kilmaluag Formation was deposited within shallow, low energy freshwater lagoons with a tenuous link to a water body of brackish-marine salinity producing a salinity gradient. Salinity is the primary control upon faunal and floral occurrences within the Lealt Shale Formation. Relative salinity tolerances are estimated for 26 ostracod species from the formation. Based upon ostracod and mollusc data this formation has rapidly and frequently fluctuating palaeosalinity values. O isotope analyses of the bivalve Praemytilus strathairdensis show a positive correlation with the palaeosalinity fluctuations; the percentage abundances of the alga Botryococcus show a negative correlation. Variations in the adductor muscle-scar rosette of Darwinula muscula are due to the mostly ontogenetic subdivision of scars. Different fossil and Recent species of Darwinula are shown to have different rosette patterns.

No description available.

The ostracod and conodont micropalaeontology of the Silurian Ludlow/Pridoli series boundary is documented from 88 localities across Wales and the Welsh Borderland. Fourteen multielement conodont species (two in open nomenclature), eight unassigned Ozarkodina elements and ten ostracod species (four in open nomenclature) are described from the Upper Whitcliffe and Downton Castle Sandstone formations and their lateral equivalents in Wales and the Welsh Borderland. A septimembrate prionodontid conodont apparatus Coryssognathus dubius (Rhodes, 1953) is reconstructed from discrete elements. Original calcareous valves of the ostracod Frostiella groenvalliana and moulds of open and partially open ostracod carapaces are described for the first time from the Welsh Basin. The Upper Whitcliffe Formation and its lateral equivalents are characterised by the ostracod Calcaribeyrichia torosa and the conodonts Ozarkodina confluens, Ozarkodina excavata, Panderodus serratus and Coryssognathus dubius. The Downton Castle Sandstone Formation and its lateral equivalents are characterised by the ostracods F. groenvalliana, Londinia arisaigensis, Londinia fissurata and Nodibeyrichia verrucosa. Conodont trends across the shelf area of the Welsh Borderland reflect an increasingly turbulent environment towards the top of the Ludlow Series. The sudden ostracod faunal change at the base of the Downton Castle Sandstone at Ludlow (shelf) contrasts with a gradual change at Long Mountain (basin) and parallels shelf-basin palynofacies changes. Variations in ostracod frequency, faunal composition and carapace preservation in the Downton Castle Sandstone Formation at Ludlow coincide with minor lithofacies variations. Local variations in the frequency of ostracods and land plant spores may be related to proximal channels delivering sediment off an irregularly prograding shoreline. Ostracod faunas correlate the base of the Downton Castle Sandstone across the Welsh Borderland to localities in E central Wales where bone beds are absent. Combined conodont and ostracod evidence suggests that the base of the Pridoli Series is concurrent with the base of the Downton Castle Sandstone Formation in Britain.