bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evidence for dextral oblique‐slip faulting in the shelve ordovician inlier, welsh borderland: Implications for the South British Caledonies
Authors: Lynas B. D. T. 
Published: July 2010

AbstractRecent work in the Shelve Ordovician Inlier has produced a variety of evidence for a period of deformation dominated by a braided system of dextral oblique‐slip faults of pre‐upper Llandovery age. Displacement amounts along individual fault strands are generally less than 2 km, but the aggregate displacement across the whole Inlier up to and including the Pontesford‐Linley Fault, must have been much greater. The fault structures found in other parts of Wales are compared to those of the Shelve Inlier, and it is concluded that this style of faulting was of importance in Wales, though it was mostly of pre‐Silurian age. The significance of the fault systems in terms of the late Precambrian to early Caledonian structural framework of Southern Britain is discussed with reference to examples from other parts of the world.
Sedimentary environments and facies of the subtropical mgeni estuary, Southeast Africa
Authors: Cooper J. A. G. 
Published: July 2010

AbstractThe Mgeni Estuary is situated on the subtropical, mainly microtidal Natal coast. Modern sedimentary environments in the estuary comprise two groups. Barrier‐associated environments include inlet channel, inlet beachface, tidal delta, washover fans, transverse intertidal bars and aeolian dunes. Estuarine environments include subtidal channels, interidal bars, back‐barrier lagoon, tidal creek, tidal creek side‐attached bars, creek mouth bar, mangrove fringe and supratidal mudflats. Each sedimentary facies is described in terms of grain‐size, sedimentary structures, and sedimentary processes. The distinctive flora and fauna play an important role in facies recognition. Vertical sequences produced by infilling of the estuary and subsequent coastal erosion are discussed. The facies are considered sufficiently distinct to warrant recognition in the geological record.
Processes of alluvial fan sedimentation, basal rozel conglomerate formation, la têcte des hougues, Jersey, Channel Islands
Authors: Went D. J. , Andrews M. J. , Williams B. P. J. 
Published: July 2010

AbstractThe Rozel Conglomerate Formation, a coarse alluvial fan deposit, overlies the Bouley Rhyolite Formation beneath the headland called La Tete des Hougues, on the north coast of Jersey, Channel Islands. Here the rhyolites form an exhumed palaeotopography which in places is smoothly, but irregularly, eroded. Locally however, there is preservation of a deep Lower Palaeozoic weathering profile. Breccia is preserved spalled from these weathered profiles as a fossil scree deposit, which has subsequently been hydraulically reworked in a palaeotopographic low.Overlying the breccia is a prograding succession of alluvial fan sediments. A 4m thick, upwards‐coarsening sequence of silty sandstones and fine pebble conglomerates is succeeded by the incision of a 3m deep channel. This is overlain by a 28m thick, upwards‐fining sequence of coarse debris flow and streamflood conglomerates. The lower unit is interpreted as a prograding fan sector of reworked fan material, whilst the upper unit is thought to reflect the avulsive initiation and gradual abandonment of a fan lobe sourced from a northern hinterland.
Lithostratigraphy and structure of the old red sandstone of the Northern Dingle Peninsula, Co. Kerry, Southwest Ireland
Authors: Todd S. P. , Williams B. P. J. , Hancock P. L. 
Published: July 2010

AbstractThe lower part of the Old Red Sandstone in the Dingle Penisula has been previously assigned to one lithostratigraphic group (Dingle Group) despite marked variations in sedimentary facies. However the apparently oldest non‐marine sequence in the northwest of the peninsula has sedimentary and lithological attributes that contrast strongly with those of the late Silurian‐early Devonian Dingle Group to the south. This northern sequence, here renamed the Smerwick Group, evolved independently of the Dingle Group in a separate basin of deposition. Field relationships between the two groups in the north of the peninsula are interpreted as indicating that the Smerwick Group overlies, with angular unconformity, a normal Dingle Group succession. Similarly, it is argued that the Smerwick Group overlies, with angular unconformity, the Dingle Group in the northwest of the peninsula, but there the Dingle Group is attenuated, represented only by a conglomerate unit some 10 m thick. In the absence of biostratigraphic evidence the age of the Smerwick Group is poorly constrained. Nevertheless, we propose a tectonic model that suggests that the Smerwick Group evolved within a small extensional half‐graben on the northern margin of the Munster Basin. This model accounts for the stratigraphic and structural relationships observed, and implies that the Smerwick Group is of Late Devonian age.
The carboniferous lithostratigraphy of Southeast County Limerick, Ireland, and the origin of the shannon trough
Authors: Strogen Peter 
Published: July 2010

AbstractThe Carboniferous succession in southeast County Limerick, on the southeastern margin of the Shannon Trough, is Courceyan to mid‐Namurian in age and over 1900 m thick. The lithostratigraphy is described in detail. Its most important aspect is the presence of two thick volcanic sequences, a Chadian one of the alkali basalt to trachyte suite and one of Asbian age dominated by limburgites and ankaramites. The associated Dinantian carbonates are of shelf or ramp facies throughout, and no fundamental division into shelf and basin facies occurs as in the Dublin and Craven Basins in early Viséan times. Rapid differential subsidence between this area and the Shannon Estuary began during deposition of the late Courceyan to early Chadian Waulsortian facies but was less marked in the remaining Viséan when much of the volcanic topography was preserved by rapid basinal subsidence. There was basinal inversion in the late Dinantian to lower Namurian, followed by renewed subsidence in mid‐Namurian times. This contrasts with the continuous rapid subsidence of the area further west on the Shannon Estuary. This behaviour, together with a comparison of that of nearby Carboniferous basins such as the Dublin, South Munster, and Craven Basins, which lack substantial volcanic sequences, suggests an origin in a transtensional regime rather than one of simple crustal stretching.
Age of the ordovician andesitic conglomerate of castle hill, Montgomery, Powys, Wales
Authors: Cave R. , Dean W. T. , Hains B. A. 
Published: July 2010

AbstractMarine fossils including Broeggerolithus broeggeri (Bancroft) and Salterolithus caractaci (Murchison) collected from strata surrounding the andesitic conglomerate of Castle Hill, Montgomery prove that the volcanic event which produced it, and possibly also the andesite of Moel‐y‐Golfa 10 miles to the NNE, was of Caradoc (early Soudleyan) age.
Anomalous vergence patterns on the rhoscolyn anticline, anglesey: Implications for structural analysis of refolded regions
Authors: Lisle Richard J. 
Published: July 2010

AbstractTraditional methods of mapping folded regions rely heavily on vergence or minor structures (folds and intersecting foliations) to confine the position of major folds of the same generation. It is argued on theoretical grounds that in certain circumstances the vergence of early structures can become reversed by later deformation. Natural examples of this vergence reversal occur on the NW limb of the Rhoscolyn Anticline in Anglesey. Lack of awareness of the possibility of this phenomenon could lead to serious misinterpretation of data from less completely exposed folded regions.
The lower carboniferous (dinantian) of the Swords area: Sedimentation and tectonics in the Dublin Basin, Ireland
Authors: Jones Gareth L. L. , Somerville Ian D. , Strogen Peter 
Published: July 2010

AbstractThe litho‐ and biostratigraphy of the Lower Dinantian succession in a deeper part of the Dublin Basin is described. The sub‐Waulsortian Malahide Limestone Formation (emended) is described fully for the first time, and has proved to be very much thicker than was previously suspected, in excess of 1200 m. Succeeding the ‘Lower Limestone Shale’ unit, which is transitional from the underlying Old Red Sandstone facies, the following six new members are recognized: Turvey Micrite Member, Swords Argillaceous Bioclastic Member, St. Margaret's Banded Member, Huntstown Laminated Member, Dunsoghly Massive Crinoidal Member and Barberstown Nodular Member (top).The Malahide Limestone Formation is overlain by ‘Waulsortian’ limestones of the Feltrim Limestone Formation (new name) which form overlapping and isolated mudmounds with complex relationships with their enclosing non‐mound facies. Though very much thicker, the Courceyan succession is comparable with that elsewhere on the south side of the Basin, and is part of the Kildare Province (Strogen and Somerville 1984). Isopach maps for the region show that this province and the North Midlands are separated by the deepest part of the Dublin Basin, named the ‘East Midlands Depocentre’, in which a shale‐dominant facies is present. The top of the ‘Waulsortian’ is of early Chadian age. Formations younger than this are dominated by basinal calcareous shales (Tober Colleen Formation) and by storm deposits and calciturbidites with appreciable terrigenous input from the east (Rush Formation).The Courceyan main shelf conodont biozones are also greatly thickened in this area. ThePseudopolygnathus multistriatusBiozone (> 300 m thick) is succeeded by a very thick (> 900 m)Polygnathus mehliBiozone. The base of the Chadian is considered to occur below the top of the Feltrim Limestone Formation and, although equivocal, may be diagnosed in the Dublin Basin by the first appearance of the problematic microfossilSphaerinvia piaiand a primitive form of the calcareous algaKoninckopora.In the late Courceyan, the Swords area was part of a gently sloping shelf extending northwards into the basin. During deposition of the Feltrim Limestone Formation there was major deepening and there is evidence of initial break up of the Dublin Basin by faulting into separate blocks. By Chadian time the Basin was definitely subsiding by fault displacements and basinal limestones contain shallow water faunas and littoral sand and pebbles derived by turbidite flows from the margins of the higher blocks. The early subsidence was apparently by pure flexure, but in the Viséan the Dublin Basin was fault‐controlled, differing from the adjacent Shannon Basin in having both margins strongly faulted.
The farnacht formation along the south side of the clew bay fault zone, Western Ireland: Its chemistry and age of metamorphism
Authors: Max M. D. , Rex D. , Winchester J. A. 
Published: July 2010

AbstractThe tectonically isolated Farnacht Formation consists of calc‐alkaline dacitic‐andesitic lavas of volcanic arc affinity. It is situated immediately to the south of the Clew Bay Fault Zone (western continuation of the Highland Boundary Fault Zone of Scotland) in the northeast corner of the Lower Palaeozoic South Mayo Trough in northwest Ireland. It has been metamorphosed to biotite grade greenschist facies following the development of a pervasive, c‐s composite muscovite, quartz, and feldspar schistosity. The Farnacht Formation may comprise a terrane that is directly unrelated to nearby Ordovician and Silurian rocks; its present position was fixed largely by Wenlock times.The age of the Farnacht Formation and the deformational event(s) that produced the schistosity are not known. 40Ar/39 Ar step heating from four specimens have dated the crystallization of biotite at from 422 ± 2 to 405 ± 14 Ma with a mean age of 413 Ma. These ages date either the post‐D2, pre‐D3 metamorphic peak, or a hornfelsing of the same structural age related to an unseen thermal source, and provide a minimum age for the end Silurian ‐ early Devonian Caledonian tectonothermal activity in the northeast part of the South Mayo Trough.
Soil‐zone microfabrics in calcrete and in desiccation cracks from the upper Jurassic purbeck formation of dorset
Authors: Andrews Julian E. 
Published: July 2010

AbstractSoil‐zone microfabrics, alveolar‐septal structure, needle‐fibre calcite, and calcans are described from horizontal calcrete layers, stringers, and infillings in vertical desiccation cracks from an Upper Jurassic limestone in the Lower Purbeck Formation of Dorset. These calcrete palaeosols occur in an oolitic limestone (the Hard Cap) which represents former evaporitic lagoonal to carbonate mudflat environments. The calcretes occur 6‐10 cm below the Great Dirt Bed, a former rendzina soil with rooted tree remains. Desiccation cracks and vugs formed in the oolitic sediment before Great Dirt Bed times. After formation of the Great Dirt Bed, soil‐water rich in dissolved CaCO3 preferentially flowed through natural conduits in the underlying sediment, namely the desiccation cracks and vugs. Calcrete precipitated in these cracks and vugs around decaying plant roots, and probably, during more arid (evaporative) climatic periods. These palaeosol microfabrics are among the first to be described from the British Jurassic and were probably preserved due to the semiarid Lower Purbeck climate where rapid oxidation of organic matter limited the amount and strength of carbonic acid generation, thereby limiting extensive dissolution of early formed soil‐zone carbonate. Early diagenetic cementation of the sediment also aided microfabric preservation by sealing off soil‐zone structures from subsequent diagenetic fluids.
The arenig in South Wales: Sedimentary and volcanic processes during the initiation of a marginal basin
Authors: Traynor John‐Joe 
Published: July 2010

AbstractMarine clastic sediments and volcanics of Arenig (Ordovician) age crop out in South Wales. These were deposited after presumed late Tremadoc erosion and subsequent arc volcanicity. Arenig sedimentation was transgressive, and followed significant erosion of the arc volcanics. Arenig conglomerates, sandstones, and mudstones were deposited in deltaic and turbiditic systems. Storm and tidal processes influenced the shallow marine deposits. The minor rhyolitic volcanics extruded during the Arenig reflect the development of Ordovician marginal basin‐type volcanics across Wales. Five sandstone petrofacies are defined and reflect differing proportions of these volcanics and of Cambrian and Precambrian basement material. Sedimentation patterns were controlled by intra‐Arenig tectonism during an overall rise in sea level. Facies and petrofacies were ponded in small, interconnected, marine sub‐basins. Earliest Arenig tectonism and sedimentation, also recognized in North Wales, reflects the initiation of a marginal basin in Wales.
An ordovician fauna from Lough Shee, Partry Mountains, Co. Mayo, Ireland
Authors: Harper D. A. T. , Graham J. R. , Owen A. W. , Donovan S. K. 
Published: July 2010

AbstractAn hitherto undocumented early Ordovician fauna from mudrocks at Lough Shee in the Partry Mountains contains species of sponge, machaeridian, bivalve, gastropod, cephalopod, brachiopod, and trilobite, together consistent with a deep‐water setting marginal to the North American province. The trilobite and brachiopod data suggest a correlation of the Lough Shee mudrocks with the upper Whiterock Stage (equivalent to a level near the D. ‘bifidus’ – D. murchisoni boundary, within the middle Llanvirn). The sparse, low‐diversity assemblage is specialized and demonstrates the development of aspects of the Whiterock fauna in the South Mayo Trough.
Storm‐influenced shelf deposits from the silurian of Western Ireland: A reinterpretation of deep basin sediments
Authors: Nealon T. , Williams D. Michael 
Published: July 2010

AbstractThe Lough Muck Formation (Wenlock) is part of the Silurian succession of North Galway, western Ireland. The formation had originally been interpreted as a transitional sequence between shelf and basinal facies in the succession. Its three members (1, 2, and 3 of Laird and McKerrow 1970) were envisaged as representing deposits of the continental rise, slope, and shelf respectively. A subsequent interpretation suggested that the two upper members were of shallow marine origin and that the proposed major Wenlock regressive event was already extant by the time of deposition of Member 2. In this paper we examine Member 1 to ascertain its environment of deposition and thus refine the sea level curve for this element of the Silurian.Member 1 may be divided into five lithofacies A to E. Facies A comprises amalgamated sandstones with low‐angle cross‐stratification. Facies B consists of couplets of erosively based coquinas containing a low‐diversity parautochthonous fauna and graded, laminated sandstones. These couplets are interbedded with thin laminated siltstones. Facies C is characterized by parallel laminated siltstones and discontinuous, erosively based sandstones. Facies D consists of fossiliferous siltstone and Facies E of thin sandstones with low‐angle cross‐lamination. Facies A and B are interpreted as shoreline deposits based upon comparison with published descriptions of such deposits elsewhere. Facies, C, D, and E, lateral equivalents of the first two facies, are interpreted as deposits which accumulated further offshore. The presence of couplets consisting of a coquina and overlying laminated sandstone, and fossil distribution, the presence of amalgamated beds and low‐angle cross‐stratification suggest the influence of storms on this shallow‐water sequence. A palaeoreconstruction is proposed which envisages a shelf deepening to the southeast off a shoreline which had an approximately northeasterly orientation.
Genesis of fragmental carbonate rocks in the Mesozoic and Tertiary of Mallorca, Spain
Authors: Adams A. E. 
Published: July 2010

AbstractFragmental carbonate rocks are common in the Mesozoic and Tertiary succession of Mallorca, in the western Mediterranean. On the Formentor peninsula at the northeastern end of the Sierra Norte, two phases of fragmentation post‐date Liassic platform carbonate and its subsequent reworking, and predate deposition of marine Burdigalian sediments. Phase 1 fragmentation resulted in brecciated rocks with angular fragments often little displaced, cemented by coarse calcite. Brecciated rock passes into veined or unbrecciated rock over short distances. These breccias are interpreted as the products of collapse during solution of an evaporite after uplift during the early Tertiary. Phase 2 fragmentation is related to the unconformity with Miocene sediments and is interpreted as a product of karstic processes operating prior to subsidence and deposition of Miocene marine conglomerates. Multiple brecciation is common, yielding complex fragmental rocks, but permitting a relative dating of the two phases and other depositional and structural events.
Chadian faunas and flora from dyserth: Depositional environments and palaeogeographic setting of Viséan strata in northeast wales
Authors: Somerville Ian D. , Strank Angela R. E. , Welsh Anthony 
Published: July 2010

AbstractNew floral and faunal data from the oldest Dinantian limestones (Foel Formation) in the Dyserth area, suggest that these sediments are of Chadian age, rather than the Asbian age concluded by earlier workers. The basal late Chadian limestones rest conformably on Dinantian Basement Beds of ?Chadian age or older.The initial inundation of St. George's Land occurred during Chadian times, when shallow‐water marine limestones accumulated in the Dyserth area and further to the south, together with terrestrially derived siliciclastics, containing drifted plant fragments. Periodically, a restricted hypersaline lagoonal environment was established but an open marine, neritic environment with abundant stenohaline fauna prevailed in this area.These Chadian sediments accumulated on the proximal part of a carbonate ramp and are presumed to have passed laterally downslope into deeper water basinal facies with Waulsortian buildups of the Irish Sea Basin. In the later Arundian, a carbonate ramp–to–platform transition occurred, with widespread deposition of shallow‐water carbonates. In the Asbian this platform developed a rimmed margin, with buildups forming a linear belt between platform and basin.An almost complete Chadian to Brigantian Lower Carboniferous sequence can now be recognized in North Wales. This succession is comparable with the shelf succession in south Cumbria on the northern margin of the Irish Sea Basin.
A composite spessartite–appinite intrusion from Port‐na‐Blagh, County Donegal, Ireland
Authors: Elsdon R. , Todd S. P. 
Published: July 2010

AbstractA sheet‐like appinite from Breaghy Head, North Donegal, is closely associated with a spessartite intrusion. Field, mineralogical, and geochemical similarities indicate that the parent magmas were very similar, and the appinite magma may have been derived from the spessartite by small degrees of crystal fractionation. The appinite is divided into an amphibole‐rich lower part and a felsic upper part; the mineralogical contrast between the two is best explained by two‐pulse intrusion of a batch of spessartitic magma within which amphibole and pyroxene had already segregated due to crystal settling or flow sorting. Unlike other Caledonian appinites, the Breaghy Head intrusion is not one of a cluster, and appears to be an isolated development. Possible reasons for its location are discussed.
A New Interpretation of the Corallian (Upper Jurassic) Cycles of the Dorset Coast, Southern England
Authors: Sun S. Q. 
Published: July 2010

AbstractThe Corallian Group of the Dorset coast is reinterpreted as representing four regressive–transgressive cycles in contrast to previous interpretations which recognized four asymmetric regressive cycles. Each regressive sequence is separated at its top from each transgressive sequence by a sharp erosional contact. Overall, the regressive, coarsening‐up sequences are characterized by relatively low faunal diversity, dominantly vertical burrows, relatively coarse sediments with cross‐bedding and swaley cross‐stratification, and the diagenesis predominantly influenced by meteoric water. In comparison, the transgressive, fining‐up sequences are generally characterized by relatively high faunal diversity, dominantly horizontal burrows, basal lag deposits (1–2m in thickness) overlying a sharp, erosional surface, followed by clay or nodular wackestone and dominantly deep burial diagenesis. The consistence of the four regressive‐transgressive cycles with the eustatic sea‐level curve suggests that the sedimentary cycles of the Corallian outcrops may have been mainly produced by the eustatic sea‐level changes. Tectonic movements may have been important in generating localized unconformity, relatively coarse clastic sediment influxes and rapid lateral facies variations. The recognition of storm‐ and tidally‐related sedimentary features suggests that the Corallian Group of the Dorset coast may have been deposited in a storm‐ and tidally‐influenced shallow epicontinental shelf.