bluuebunny/crossref_metadata_2025_split huggingface dataset:
A re‐examination of the type Arenig Series
Authors: Zalasiewicz J. A. 
Published: July 2010

AbstractThe stratotypc of the Arenig Series (Ordovician System) and its boundaries are critically re‐examined. The lithostratigraphy and biostratigraphy of the Tremadoc, Arenig, and Llanvirn age rocks at Arenig Fawr, North Wales that were constructed by Feamsides in 1905 are amended. The Arenig Series at Arenig is represented by the Camedd Iago Formation which was established by Lynas (1973) in the Migneint area. Examination of the sparse graptolite faunas indicates that the type Arenig Series is incomplete, only the extensus Zone having been recognized with certainty. There is a possible unconformity at the base and a probable unconformity at the top, and on present knowledge the succession cannot be correlated precisely with what are considered to be Arenig sequences elsewhere. It therefore may prove necessary to redefine the Arenig Series at a more useful type section. It is suggested that the Carmarthen district may provide a suitable stratotype.
Fluvial to marine transition in the Ordovician of Ireland–A humid‐region fan‐delta?
Authors: Pudsey C. J. 
Published: July 2010

AbstractThe Mweelrea Group (Llanvirnian) in the South Mayo Inlier, western Ireland, consists mainly of coarse shallow‐water sandstones with minor slates, cobble conglomerates, and ignimbrite tuffs. The Glenummera Formation at the base (up to 600 m), dominantly well‐cleaved slates with some slump features, was deposited in a slope to deep marine shelf environment. A coarsening upward sequence at its top reflects the interaction of fluvial and marine processes, coarse clastic sediments having prograded from the southeast. The rest of the Mweelrea Group (2100 m in the northwest) is dominated by coarse trough cross‐bedded sandstone with little evidence for channelling. Three lenticular marine slates (Glendavock, Uggool, and Glenconnelly Formations), up to 200 m thick, wedge out to the southeast. A humid alluvial fan‐fan‐delta model can explain many features of the Mweelrea Group. Fans built out to the northwest into a relatively small basin with negligible tides and moderate wave energy. Marginal sediments were reworked by waves, occasional storms, and a burrowing fauna.
The stratigraphy and sedimentology of the Ordovician Partry Group, southeastern Murrisk, Ireland
Authors: Williams D. M. 
Published: July 2010

AbstractThe uppermost part of the Ordovician succession in southeastern Murrisk, western Ireland, consists of coarse‐grained sedimentary rocks and tuffs, the Partry Group, hitherto subdivided into the Mweelrea Formation, unconformably overlain by the Maumtrasna Formation. The age of the lower part of the succession is late Llanvirn whilst that of the upper part is unknown. Evidence is presented to show that the two formations are lateral equivalents. Consequently the Mweelrea Formation is redefined and the Maumtrasna Formation becomes redundant. The revision of the stratigraphy enables a coherent sedimentological model for the group to be proposed. The sediments of the Mweelrea Formation were deposited on alluvial fans and distally‐equivalent alluvial plains and delta fans. The direction of sediment transport was towards the north and northwest.
The recognition of the Asbian/Brigantian boundary fauna and marker horizons in the Dinantian of North Wales
Authors: Somerville Ian D. , Strank Angela R. E. 
Published: July 2010

AbstractFor the first time the stratigraphically important brachiopod Davidsonina septosa (Phillips) has been located in thickly bedded pale grey, late Asbian limestones in North Wales. Above these limestones are thinly bedded dark grey Brigantian limestones, which have yielded a rich and diverse coral‐brachiopod fauna, including Lonsdaleia floriformis (Martin). The Girvanella Nodular Bed is recorded for the first time in this region, some distance above the base of the Brigantian. The boundary between the two major lithofacies is marked by a prominent palaeokarstic surface and coincides with a significant faunal change, both in the macrofauna and microfauna that serves to identify the boundary between the Asbian and Brigantian Stages. The discovery within late Dinantian successions of certain diagnostic corals, brachiopods, and algae outside their accepted restricted stratigraphical ranges, casts doubt on their reliable use as Asbian or Brigantian zone fossils.
Lower Palaeozoic lithostratigraphical classification in the English Lake District
Authors: Moseley F. 
Published: July 2010

AbstractIn the English Lake District lithostratigraphical classification has not kept pace with either the international and national codes or the code of the Geological Society (Holland et al. 1978). Probelms arise, firstly, from acceptance by several of those working in the area, of terms used in by‐gone days, such as ‘Borrowdale Volcanic Series’, and secondly, and more importantly, because individuals have specialized on certain parts of the sequence (the Skiddaw Slates, the Coniston Limestone, etc.), and have erected classifications for these rocks without reference to other parts of the succession. These classifications are examined and modified in such a way that the lithostratigraphical subdivisions are consistent for the whole of the Lower Palaeozoic sequence of the Lake District, and also relate to the international code as it is applied in other regions. The basic Lake District stratigraphical terminology of the last century is, however, retained in all its essentials.
Peritidal carbonate facies models: A review
Authors: Wright V. P. 
Published: July 2010

AbstractExisting facies models for peritidal carbonates are limited in number and do not reflect the wide spectrum of possible types. The major depositional processes in peritidal carbonate environments are reviewed in order to stress the complex nature of the systems. The tidal channel model is critically discussed and it is suggested that channel deposits may be of minor importance in typical shoaling‐up sequences. The possible causes of multiple asymmetrical sequences are reviewed.
Production of multi‐décollement folding by pressure release in the formation of a microbreccia at Lough Doon, Donegal, eire
Authors: Holder M. T. 
Published: July 2010

AbstractAn unusual matrix‐supported microbreccia of Caledonian age is described from the Dalradian rocks of Donegal. Field and textural relationships indicate that the breccia formed ‘in situ’ by a non‐dilational mechanism during regional deformation. The presence of breccia veins of low competancy during this deformation caused multi‐décollement folds to be formed adjacent to the breccias. A cyclical mechanism of formation of these breccias is proposed in which fluctuations in the overpressuring of pore fluids escaping from an adjacent crystallizing appinite mass caused periodic excursions from ductile to brittle deformation during the regional folding.
Generic identification of fragmentary Quaternary molluscs by amino acid chromatography: A tool for Quaternary and palaeontological research
Authors: Andrews J. T. , Miller G. H. , Davies D. C. , Davies K. H. 
Published: July 2010

AbstractThe amino acid signature of fourteen genera of Mollusca, both Bivalvia and Gastropoda, was determined on over 300 individual valves. Examination of eight specific sets of amino acid ratios (for example: aspartic acid/glutamic acid, leucine/valine) indicates that these 14 genera (Patella, Littorina, Nucella, Buccinum, Turritella, Macoma, Scrobicularia, Mytilus, Cerastoderma, Arctica, Gtycymeris, Venus, Mya, and Hiatelld) can be distinguished one from another with a high degree of certainty.Discrimination between genera can be based on quantitative assessment of the probability of an individual analysis belonging to a specific genus. We conclude that the amino acid signature is sufficiently distinct that small shell fragments can be assigned to a genus on the basis of the amino acid chromatography. In some instances, for example Littorina, it may even be possible to identify fragments to specific species.
The Ludlow‐Downton transition at Kington, Herefordshire
Authors: Holland C. H. , Williams E. M. 
Published: July 2010

AbstractBiostratigraphy and lithostratigraphy of some exposures of upper Ludlow and lower Downton rocks near Kington, Herefordshire are described in detail. Temporary exposures created during the construction of the new Kington by‐pass are particularly informative. One small exposure of Lower Whitcliffe Formation is recorded. The Upper Whitcliffe Formation is well displayed in characteristically fossiliferous shelly siltstones. The Downton succession begins with the Ludlow Bone Bed Member. This and the succeeding Platyschisma Shale Member complete the local development of the Downton Castle Sandstone Formation.
Regional variations in cleavage and fold development in North Wales
Authors: Campbell S. D. G. , Reedman A. J. , Howells M. F. 
Published: July 2010

AbstractThe arcuate pattern of the main Caledonian cleavage and associated fold axial plane traces in North Wales is due partly to NW‐SE compression with tectonic transport to the southeast against the concealed crop of the Tan y grisiau Microgranite. Low‐angle cleavage close to the microgranite is shown to be a local variant of the regional cleavage formed during the main deformation and not an earlier phase as previously supposed. Transcurrent movements along several major fault systems are also related to compression around the microgranite and the Harlech Dome block.
The intrusion and deformation of Tertiary minor sheet intrusions, west Suardal, Isle of Skye, Scotland
Authors: Nicholson R 
Published: July 2010

AbstractThe arcuate Broadford anticline of south‐central Skye folds a sequence of strata ranging in age from late Precambrian to Jurassic. The Ordovician carbonate rocks of the core of the anticline are strongly extended parallel to bedding and deformation at some localities reaches up into unconformable Mesozoic strata. Three classes of Tertiary minor intrusion are recognized in the deformed sediments. The younger two are post‐kinematic. The effect of deformation on discordant sheets of the oldest class is obvious, as they are folded. It now seems, however, that the boudins previously reported (Nicholson 1970; Longman and Coward 1979) are sections through finger‐like igneous bodies (Farmin 1941; Pollard et al. 1975). Stiff in relation to the carbonate country rock, the latter retained igneous textures and chilled margins when deformed. Deformation probably took place as the main period of plateau‐lava eruption ended and the succeeding phase of shield volcanoes and major intrusive centres began. As deformation is restricted to the core of an arcuate fold forming part of a volcanic complex, it may speculatively be suggested that the deformed rocks lie above an arcuate diapir, formed in an acid magma body subjected to volcanic load.
The brachiopod fauna of the Meadfoot Group (Lower Devonian) of the Torbay area, south Devon
Authors: Evans K. M. 
Published: July 2010

AbstractThe lithology and sedimentology of the Meadfoot Group around Torbay are briefly discussed. The brachiopod fauna is tabulated, with ranges, and is considered to indicate an Emsian age. The fauna and environment of deposition of the Meadfoot facies (Lower‐Upper Emsian) and the Staddon facies (Upper Emsian) are discussed and are interpreted as representing Outer Shelf and Inner Shelf positions respectively.
Facies variation in Waulsortian buildups. Part 2; Mid‐Dinantian buildups from Europe and North America
Authors: Lees Alan , Miller John 
Published: July 2010

AbstractUsing detailed petrographic analysis and a new method of handling similarity coefficients, samples from over 30 Mid‐Dinantian (Upper Tournaisian‐Lower Viséan) carbonate buildups from Europe and North America are compared with the Waulsortian facies of Belgium. The same component types are present and they bear very similar relationships to. one another. This is very significant because the assemblages of components in Belgium have recently been interpreted in terms of water depth (Lees et al. 1985).Four Waulsortian Phases are recognized, corresponding to the Belgian depth‐related assemblages. They represent growth in a range of marine environments from fairly deep, aphotic (probably more than 300 m) through to the photic zone (less than 120 m).Logging and mapping of phases allows growth patterns of individual buildups and buildup complexes to be interpreted as products of changing depositional environments. The very existence of the phases provides new information on the origin of the buildups. It also reveals that there was a fundamental growth mechanism independent of the preserved biota.
The deep structure of Derbyshire
Authors: Smith K. , Smith N. J. P. , Holliday D. W. 
Published: July 2010

AbstractPre‐Carboniferous basement beneath Derbyshire is disposed in two southwest‐dipping tilt blocks (Eyam and Woo Dale Blocks), which are separated by a major north‐dipping growth fault (the Bakewell Fault). The surface expression of the Bakewell Fault is largely concealed by late Dinantian carbonate shelf sediments, but its position and trend, which can be inferred from borehole and geophysical evidence, have exerted a control upon mineralization and volcanism in Derbyshire. During the Holkerian, the Bakewell Fault acted as the axis of a broad anticlinal fold or drape structure, which subsequently influenced the position of the overlying Asbian carbonate shelf. Tilt blocks are arranged symmetrically beneath the southern Pennine Basin, with north‐dipping blocks, such as the Askrigg Block, at the northern margin mirrored by south‐dipping blocks beneath Derbyshire in the south.
The Dinantian biostratigraphy of a deep borehold near Eyam, Derbyshire
Authors: Strank Angela Ft E. 
Published: July 2010

AbstractDetailed micropalaeontological analysis of the Eyam Borehole is presented. Dinantian strata of Upper Tournaisian to ‘middle’ Brigantian age have been recognized lying unconformably on top of Ordovi‐cian (?Llanvirn) basement beds (Dunham 1973). The early Tournaisian and late Brigantian beds are missing probably due to non deposition and erosion respectively. Throughout the Dinantian a shallow shelf environment is represented by a thick series of anhydrites and dolomites in the Upper Tournaisian. The new name Middleton Dale Anhydrite Series is proposed for these lowest Dinantian beds. The chronostratigraphy erected is compared with that outlined for Eyam by Dunham (1973) and for the Woo Dale Borehole by Strank (in press).
Tectonic deformation of a channel sandstone
Authors: Tringham M. E. 
Published: July 2010

AbstractAn investigation has been made of a structural complex in southwest Wales. The complex comprises a zone of folds and faults within Upper Carboniferous rocks of the Variscan fold belt, interpreted to have formed by tectonic deformation of a large channel sandstone. Sedimentary features include basal and internal erosion surfaces, an onlapping channel fill, lens‐shaped beds of mudstone with slumped layers, and discontinuous conglomerate and coal beds. These features strongly influenced ensuing tectonism, with the channel axis now coincident with a composite anticline. Some bedding discontinuities acted as surfaces of decollement, and lens‐shaped beds were folded disharmonically. This example will provide an analogy for use in other deformed sedimentary terrains, where channels may occur.Acknowledgements. I wish to thank Drs M. C. Cooper, R. M. Tucker and B. P.J. Williams for their valuable comments on the manuscript. I also acknowledge receipt of a NERC studentship held at the University of Bristol, supervised by Dr P. L. Hancock.
Non‐axial planar cleavage and Caledonian sinistral transpression in eastern Ireland
Authors: Murphy Finbarr C. 
Published: July 2010

AbstractTransected F1 fold structures in eastern Ireland are associated with subhorizontal stretching in the S1, cleavage whereas axial planar cleavage contains a vertical elongation direction. This suggests that the non‐axial planar cleavage was influenced by a distributed strike‐slip ductile shear.A major NE‐SW trending F1 syncline is described in which the minor F1 folds show systematic variations in cleavage transection parameters. On the steep limb of the major syncline the cleavage transects the minor F1 folds in a consistently clockwise sense, whereas on the normal limb anticlockwise transected folds are seen. Axial planar cleavage occurs at the core of the major syncline.Fold profile analysis indicates that the buckling of the layers began before the initiation of the cleavage. Open, parallel folds at the major synclinal hinge zone are progressively ‘flattened’ on the steep limb towards a major D1 sinistral transcurrent fault. The angular transection, A, attains a maximum of 15° clockwise which diminishes to <5° at higher strains adjacent to the major fault. Incremental fibre growth in pressure shadows show a two‐stage tectonic strain superposition of vertical pure shear followed by sinistral transcurrent simple shear during the development of the clockwise transecting cleavage. Anticlockwise transected folds were influenced by local dextral strike‐slip on the southern margins of a rigid terrane. As a regional feature, the clockwise transection is explained by a sinistral transpressive deformation of end‐Silurian age.
A peridotitic komatiite from the Dalradian of Shetland
Authors: Flinn Derek , Moffat D. T. 
Published: July 2010

AbstractKomatiite lavas occur in the Dunrossness Spilitic Group in southeast Shetland in the Cunningsburgh area. This metavolcanic group is the easternmost member of the East Mainland Succession of Shetland and probably the youngest. It overlies a thick succession of deep‐water metasediments and metavolcanic rocks probably forming part of an extensional basin and has been correlated with a part of the upper Dalradian of Scotland. Komatiites are not common in rock sequences as young as this. Their eruption is thought to require tectonic and thermal conditions which have been unusual since Archean times. Such conditions could arise when the crust beneath an extensional basin splits to form a constructive margin.
Structure, petrology and geochemistry of the Abu Dom alkaline ring‐complex, Bayuda Desert, Sudan
Authors: O'Halloran D. A. 
Published: July 2010

AbstractThe Abu Dom complex is one of a cluster of Younger Granite ring‐complexes piercing the Proterozoic gneisses of the Bayuda Desert of Sudan. Intrusive rocks predominate and range from early metaluminous syenites to later peralkaline syenites and granites. They are disposed as ring‐dykes, nested intrusions, and cone‐sheet swarms. Field evidence and geochemical variation indicate that the peralkaline rocks evolved from a metaluminous syenitic parent magma as a result of high‐level fractionation. The suite carries a clear within‐plate signature exemplified by marked enrichments in HFS elements such as Zr and Nb.
Pre‐Caledonian basement in Ireland and its cover relationships
Authors: Max M. D. , Long C. B. 
Published: July 2010

AbstractPre‐Caledonian basement is exposed in three areas within the Irish orthotectonic Caledonides: 1. In northwest County Mayo the Erris Complex comprises the Annagh Division, which is largely Grenvillian but includes older gneisses, and the Inishkea Division, which is probably equivalent to the older Moines of Scotland. 2. In the northeast Ox Mountains, Rosses Point and Lough Derg inliers there is a granulite fades, dominantly metasedimentary basement which is probably late Grenville in age. 3. Laxfordian and probably older gneisses are seen in the Inishtrahull Platform northeast of Malin Head, County Donegal.In addition, some gneisses within the belt of ‘Connemara migmatites’ in south Connemara may be fragments of allochthonous basement and some high grade metamorphic rocks in the Tyrone Central inlier have been referred to as pre‐Caledonian basement, but there is at present no conclusive support for these suggestions. The Ox Mountains succession seen in the Clew Bay region and the southwest and central Ox Mountains is probably not pre‐Caledonian basement.Basement in the paratectonic Caledonides is confined to the Cadomian and possibly pre‐Cadomian Rosslare Complex (older than 625 Ma) and the nearby late Precambrian (to early Cambrian ?) Cuilenstown Formation in southeast County Wexford. In addition, an unseen block of basement defined by magnetics immediately to the north of the Dingle peninsula of County Kerry is probably of Rosslare Complex affinity. Granulite facies xenoiiths recovered from volcanic rocks of Carboniferous age about 70 km to the west of Dublin, indicate the character of basement there, though its age is not proven.All contacts between basement and Lower Palaeozoic Caledonian cover in the orthotectonic Caledonides are synmetamorphic slide zones and faults and in the paratectonic Caledonides the contacts are either faults, which are often rooted in older mylonites, or are unexposed and presumed to be major structural breaks.
Heterogeneous deformation and mylonitization of a granulite complex, jotun‐valdres nappe complex, Central South Norway
Authors: Koestler Andreas G. 
Published: July 2010

AbstractThe Helgedal Zone is the Caledonian, heterogeneously deformed base of the Jotun Complex, within the Jotun‐Valdres Nappe Complex (Sognefjell, South Norway). It consists of an anastomosing system of shear zones isolating lozengeshaped lenses of less deformed rocks. Structural and geometrical features are described to define the type of deformation and to evaluate the tectonic significance of this zone. Granulitic gabbros and pegmatitic dykes are deformed together in the highly strained mylonitic zones. Microtextural investigations indicate that the quantitative relation between mafic and felsic minerals and the content of quartz determine the different behaviour of the two rock types during deformation.
Sediments in the estuarine environment of the tigris/euphrates delta; Iraq; Arabian Gulf
Authors: Darmoian S. A. , Lindqvist Kristian 
Published: July 2010

AbstractStudies on surface water characters of the estuarine environment of Iraq, northwestern Arabian Gulf, define three subdivisions of salinity: oligohaline, polyhaline, and euhaline. Textural analysis reveals that surface sediments covering the bottom are composed of six distinct classes: silty clay, clayey silt, sand‐silt‐clays, clayey sand, silty sand and sand. Five physiographic subdivisions are identified and described fluvial‐estuarine, tidal mud flats (subtidal flat, lower intertidal flat, upper intertidal flat, supratidal flat), sand bars, Abdallah‐Shetana channel and submerged estuarine distributary channel and bar systems.The content of organic matter in the sediments ranges from 0.24‐3.69 per cent by weight. High values were recorded from the Abdallah‐Shetana channel while lower values are confined to sand bars and submerged estuarine distributary channel and bar systems.Carbonates, quartz, feldspar, and halite are the main mineral constituents of the non‐clay grade sediments; carbonates are present mainly as low‐magnesium calcite followed by dolomite and high‐magnesium calcite. Aragonite is present only in trace amounts. Both detrital and biogenic sources are suggested for low‐magnesium calcite. A detrital source for dolomite and a biogenic source for high‐magnesium calcite and aragonite are proposed.