bluuebunny/crossref_metadata_2025_split huggingface dataset:
A cyclicity in the early brigantian (D2) limestones east of the clwydian range, north wales and its use in correlation
Authors: Somerville I. D. 
Published: July 2010

AbstractFor the first time, minor cyclicity is described from some limestones in the lower part of the Brigantian (D2) succession of the Mold district North Wales which can be traced throughout the area enabling a detailed correlation to be established. The minor cyclicity may have been caused by eustatic sea‐level fluctuations. Periods of emergence associated with each regressive phase are demonstrated by the presence of subaerial features and terrestrial deposits. The lateral persistence of the cycles is confirmed by comparison with established faunal and lithological horizons. Correlation with other cyclic Brigantian strata in Yorkshire, Derbyshire and Bristol is briefly discussed. The Asbian/Brigantian (D1/D2) boundary in North Wales is described and distinctive faunal and lithological changes similar to those in the area of the stratotype in north England have been recorded.
An upper llandoverian turbidite sequence of the bwlch‐glas area, near aberystwyth, dyfed
Authors: Strong G. E. 
Published: July 2010

AbstractPetrographical investigation of an Upper Llandoverian turbidite sequence has been undertaken in conjunction with the primary 1:50,000 geological survey of the Aberystwyth District (Sheet 163) by R. Cave and B. A. Hains of the Institute of Geological Sciences. The sequence represents distal thin‐bedded turbidite deposition in a NW‐SE channel, with material derived from the southeast.
Geomagnetic polarity measurements from pleistocene deposits in southwest France and their chronological implications
Authors: Oldfield F. , Thompson R. 
Published: July 2010

AbstractMeasurements of palaeomagnetic inclination in sediments from the French Pays Basque, representing three of the major Pleistocene biostratigraphic subdivisions previously identified, confirm normal polarity in all cases. Taken together with the palaeobotanical, stratigraphic and geomorphological evidence they suggest that the Moulignan, Senixian and Ilbarritzian stages lie within the early part of the present Brunhes normal polarity epoch and probably correlate with some unknown part of the “Cromerian Complex”. The Bidartian is thought to lie within a normal polarity event during the Matuyama epoch and to correlate with part of the Tiglian ‘A’ sub‐stage of the Netherlands.
The longdendale landslides
Authors: Johnson R. H. , Walthall S. 
Published: July 2010

AbstractThroughout its geomorphological history the South Pennine valley of Longdendale has been especially prone to landsliding and some ten landslide areas have been identified. These prove on analysis to be bedding plane slides with a strong degree of translation but often exhibiting non‐circular rotational elements as well. Instability in the lower slopes has often led to cambering and valley bulging so that the slopes become deformed and slump earth flows developed at some sites. Several different types of landslide are examined in detail and by means of pollen analysis the slides are dated from the early postglacial to at least as recently as two thousand years B.P. although it has not yet been possible to decide when these slides started. The causes of sliding are identified, and comments are made upon.
the location of slip surfaces–which are frequently at the base of the Grindslow Shales above a sandstone aquifer;
the geomorphic processes which built up high pore‐water pressures and steep pressure gradients in the past; and
the effects of sliding on the development of hillslopes in the post‐glacial period.
Metadolerite age relationships in the dalradian of northwest donegal, Ireland and their orogenic significance
Authors: Hutton D. H. W. 
Published: July 2010

AbstractThe structural relationships of several intrusive sheets belonging to the extensive metadolerite suite of the Appin (lower) Dalradian rocks of the Creeslough area, northwest Donegal, Ireland have been examined. It is concluded that, relative to the regional chronology of deformation of the enclosing metasediments, sheet emplacement has occurred: pre‐D2; syn‐D2; between D2 and D3; and syn‐D3. The height of activity came in the post‐D2, pre‐D3 interval and coincided with the peak of regional metamorphism in the area. These relationships in Donegal are compared with those of the pretectonic basic rocks of the southwest Highlands and models are discussed.
Authigenic iron and titanium oxides in triassic red beds: (St. Bees Sandstone), Cumbria, Northern England
Authors: Ixer R. A. , Turner P. , Waugh B. 
Published: July 2010

AbstractAuthigenic iron and titanium oxides occur in three main textural varieties in the St. Bees Sandstone, a Triassic red bed succession in Cumbria. These are: (a) overgrowths of haematite, titaniferous haematite, anatase, and rutile which generally occur on detrital host grains of similar compositions. The overgrowths may occur as syntaxial rim cements or rhombohedral and prismatic projections and are always in optical continuity, (b) discrete crystals of anatase (including octahedrite) and haematite 10‐40 μm in size occur in pore spaces, and (c) fine grained ( < 1 μm) pigmentary haematite occurs as grain coatings around detrital grains and in the interstitial matrix.The euhedral nature and pore‐filling habit clearly indicate the authigenic origin of these iron‐ and titanium oxides. All three textural varieties are believed to have been precipitated from ground waters containing dissolved ferrous and titanium ions. These ions were derived from the intrastratal solution of detrital iron and titanium bearing grains including ferromagnesian silicates and iron‐titanium oxides. The precipitation of iron oxides from migrating ground waters in the manner described here goes some way to explaining how thick, uniformly red successions can be formed.
Some last glaciation drift deposits near Pontypridd, South Wales
Authors: Harris C. , Wright M. D. 
Published: July 2010

AbstractDrift deposits exposed in a large open cut are described. The basal member of the sequence consists of bedded sandy gravels, and these are overlain by a grey silty sand containing abundant striated pebbles and boulders. The uppermost deposit consists of a brown poorly sorted drift containing silty and sandy lenses. Analysis of the texture, index properties and densities of the sediments, together with the shape, lithology and fabric of the contained pebbles suggests that the basal gravels were deposited by subglacial meltwater, the grey drift is a lodgement till, and the uppermost brown rubbly drift was formed by solifluction of the till, with the addition of frost shattered sandstone from the hilltop above. It is suggested that the glacigenic sediments are of Devensian age, and the solifluction layer Late Devensian.
Rhythmic sedimentary sequences in the triassic Keuper Marl (mercia mudstone group) of cheshire, northwest England
Authors: Arthurton Russell S. 
Published: July 2010

AbstractCored boreholes in the central part of the Cheshire‐Shropshire basin form the basis of a sedimentological description of three separate parts of the Keuper Marl succession. The uppermost sequence examined is the lower part of the Middle Keuper Marl within which blocky silty mudstones and well laminated mudstones and siltstones form a rhythmically alternating pattern. Similar alternating patterns are described from the Lower Keuper Saliferous Beds and the top of the Lower Keuper Marl although, in these, the alternations are interrupted to various degrees by halite rock. The blocky and laminated facies are considered to have accumulated in emergent and flooded conditions respectively, the alternations reflecting eustatic variation.
Silurian metabentonites in County Down, Northern Ireland
Authors: Cameron T. D. J. , Anderson T. B. 
Published: July 2010

AbstractThin beds of pale green and grey ‘claystone’ in the Birkhill Shales (Lower Silurian) of County Down are positively identified as bentonite. In the overlying turbidites, previously regarded as entirely of sedimentary origin, numerous metabentonites demonstrate continuing Silurian vulcanicity.The metabentonites contrast with the enclosing sediments in mineralogy and geochemistry. Illite, with subsidiary chlorite, is the chief alteration product of the primary volcanic glass, and comprises two co‐existing polymorphs. Clay‐grade 1Md mica is derived from montmorillonite, and a coarser 2M variety may be an anchimetamorphic alteration of the former. Some beds additionally contain accessory phenocrysts of orthoclase, oligoclase, biotite or chlorite, and small amounts of apatite and ilmenite. Statistical analysis of the geochemical data indicates that primary alteration of volcanic glass to bentonite was accompanied by relative enrichment of Al, K, Rb, Zr, Nb, and Y, and depletion of Na; additional enrichment of K and Rb occurred with collapse of mixed‐layer clay to illite during Caledonian anchimetamorphism.
Sedimentary facies, production rates and facies models for recent coralline algal gravels, Co. Galway, Ireland
Authors: Bosence Daniel W. J. 
Published: July 2010

AbstractFive sedimentary facies are described from SCUBA diving examination and sampling of Mannin Bay, Ireland. A Bank facies is built up by the unattached coralline algae Lithothamnium corallioides and Phymatolithon calcareum. This autochthonous facies occurs in shallow sheltered environments. In exposed areas a rippled Clean Algal Gravel facies is found composed of coralline and molluscan debris. In intermediate energy areas a Muddy Algal Gravel facies is found with small amounts of live corallines. Sheltered creeks have a Mud facies which is partly carbonate and partly terrigenous. The shallow water coralline algal sediments are overlapped by a Fine Sand facies of mixed biogenic composition. Each facies is characterized by particular phenotypic growth forms of the unattached corallines. Rates of organic calcium carbonate production are obtained which are found to be similar to rates from shallow tropical non‐reef environments. The carbonate sediments of Mannin Bay are compared with similar sediments from Kilkerrin Bay. Ireland, from Brittany and from Falmouth Harbour. From these comparisons, facies models are proposed for these carbonate sediments. The major factor controlling facies distribution is coastal morphology. The present day shelf is considered to be too exposed to preserve complete sequences of the shallow water sediments.
A suggested re‐interpretation of the Lower Palaeozoic stratigraphy around Llanafan Fawr, Central Wales
Authors: Davies J. H. 
Published: July 2010

AbstractA recent paper by Lockley (1978) described the stratigraphy of the Towy Anticline around Llanafan Fawr, Brecknock, based on the proposition that there exists a syncline which crosses the Chwefru Valley at Lan Fach. Way up evidence from the area indicates the absence of this fold and a rearrangement of the local stratigraphical sequence is therefore necessary. The revised stratigraphy resembles much more closely that of other sections across the Towy Anticline in south Central Wales.
Lepidostrobus haslingdenensis: A new species from the Lancashire Millstone Grit
Authors: Thomas B. A. , Dytko Alicja 
Published: July 2010

AbstractA collection of microsporangiate cones is described from the topmost Namurian of Rossendale, Lancashire. The microspores are closely comparable with the dispersed spore species Lycospora noctuina, being of a type that has not been previously recorded from a fructification.
The ordovician‐silurian boundary in the garth area of southwest powys, wales
Authors: Williams Alwyn , Wright Anthony D. 
Published: July 2010

AbstractThe Ordovician‐Silurian rocks at Garth, 30 km northeast of Llandovery, have been remapped. Within the siltstone‐dominated succession, the coarser Cwm Clŷd Formation is regarded as stratigraphically equivalent to the A1 sandstone of Llandovery and has yielded a single specimen of Eostropheodonta hirnantensis from near the base in the northernmost exposures. The Formation rests with a stratigraphical break on fossiliferous Rawtheyan siltstones in the south but is underlain by later Rawtheyan and abundantly fossiliferous Hirnantian sediments (Wenallt Formation) further north where the succession appears continuous. Sedimentary and faunal evidence demonstrates the shallowing of the Ashgill sea before a transgression and deepening started in late Hirnantian times. The implications of the sequence in determining the systemic boundary are discussed.
Peralkaline rhyolites from the ordovician tweeddale lavas, peeblesshire, scotland
Authors: Thirlwall M. F. 
Published: July 2010

AbstractThe riebeckite‐bearing rhyolite of Winkston Hill, Peebles, is shown to be peralkaline and may be named a pantellerite. Trace element comparison with other more altered members of the Tweeddale lavas from Wrae Hill suggests that the whole suite is peralkaline. It is thought most unlikely that the suite was developed in association with an Upper Ordovician subduction zone, and it was perhaps erupted on an oceanic island.
A tunnel section through a prograding Namurian (Arnsbergian, E2a) delta, in the western Bowland fells, north Lancashire
Authors: Johnson Eric W. 
Published: July 2010

AbstractThe Wyresdale Tunnel was driven through Roeburndale Grit Group sediments in the western Bowland Fells. An Arnsbergian age for the strata is confirmed in a palynological study. The tunnel provided a section through a prograding delta front sequence, and proved the Roeburndale Grit Group to be much thicker than previously recorded. Syndepositional instability within the deltaic sediments is illustrated by slumps and debris slides. A comparison is made with modern deltas. It is suggested that the regional variation in sediment thickness is tectonically controlled.
Glyptograptus? persculptus (Salter), its tectonic deformation, and its stratigraphic significance for the Carys Mills Formation of N.E. Maine, U.S.A.
Authors: Rickards R. B. , Riva John 
Published: July 2010

AbstractThe Carys Mills Formation of NE Maine represents the SW extension of the Matapedia Group and the White Head Formation of southern Gaspé, Quebec. This formation has yielded two main collections, one hitherto considered of Middle Ordovician age (zone 13 of Berry's 1960 Marathon, Texas, zonation) with 7 species referred to 4 genera, and one of the Early Silurian age. A revision of the supposed Middle Ordovician collections reveals that the graptolites are basal Silurian and consist of only one species, Glyptograptus? persculptus. Several hundred specimens, preserved both flattened and in three dimensions, the latter in iron pyrites, allow an analysis of both the rhabdosome changes wrought by diagenetic flattening and those caused by severe tectonic deformation. It is shown that those specimens lying parallel to the bedding plane lineation caused by a high‐angle main cleavage have a silhouette appearance close to Glyptograptus tamariscus (Nicholson), whilst those at right angles to this direction superficially resemble robust Amplexograptus spp., or Diplograptus s.s., or Diplograptus s.l. spp., thus explaining the stratigraphic assignment of earlier workers. An analogue video reshaper confirms the above conclusions.This determination assigns the whole Carys Mills Formation to the Lower Silurian, but the possibility that part of the formation is of Late Ordovician age cannot be excluded. This much is suggested by the Matapedia Group and the White Head Formation which are of Late Ordovician to Early Silurian age, and the Honorat Group, which has yielded graptolites of late Middle Ordovician age.
A note on the stratigraphic relationship of the leven schist and monadhliath schist in the central highlands of Scotland
Authors: Haselock P. J. , Winchester J. A. 
Published: July 2010

AbstractThe Monadhliath and Leven Schists are separated north of Glen Roy by some 500m of psammitic rock. Junctions are gradational and conformable, and evidence from sedimentary structures indicates that all three face upwards. The two schists should not be equated, nor should the Monadhliath Schist be included in the Dalradian Supergroup unless the entire Grampian Division is also included.
Carbon isotopic change at the base of the upper permian zechstein sequence
Authors: Magaritz Mordeckai , And Peter Turner , Käding Karl‐Christian 
Published: July 2010

AbstractFluctuation of the carbon isotope composition of marine carbonates has recently been developed as a powerful tool for the identification of ocean‐wide anoxic conditions and changes in the world budget of carbon and oxygen. A change in δ13 from the normal marine values (0 to + 2%) to values highly enriched in 13C (+3·5 to 4·5%) is recorded at the base of the Zechstein sequence both in central Germany and northeastern England. The change occurred over a relatively short period of time indicating a rapid and pronounced change in the organic carbon/carbonate budget. Evidence from other Permian basins show similar highly enriched δ13C values. This change may correspond to that in carbon balance distinguished by the Garrels and Perry (1975) model and based on the change in sulphur isotopic composition during the Permian.
Palynofloras from tournaisian lacustrine and tidal sequences in slieve bloom, counties laois and offaly, Ireland
Authors: Keegan James B. , Feehan John 
Published: July 2010

AbstractTournaisian miospore assemblages are used to determine the age of some plant‐bearing horizons in the Old Red Sandstone succession of the Slieve Bloom Mountains, Counties Laois and Offaly, Ireland, and the sedimentology and conditions of deposition of the productive lithologies are described. The age of the marine transgression which terminated continental sedimentation is indicated, and the associated depositional environment is discussed. Comparisons are made with other micro‐ and macrofloras from Ireland, Britain, Canada, the U.S.S.R. and Bear Island.
Sandy gravel accumulation in a fluvial environment
Authors: Blacknell Clive 
Published: July 2010

AbstractParticle size, pebble shape, pebble fabric, discharge and flow velocity data are used to introduce a model of sandy gravel formation in Welsh gravel‐bed rivers. The development of contact‐imbrication of the typically very bladed and very platy cobbles and larger pebbles subsequently acts to significantly affect the depositional modes and patterns of small pebbles and sand particles. An important distinction is drawn between sand deposition, which can occur at or below the bed surface, and pebble and cobble deposition, which is merely a surface phenomenon.
Petrology and geochemistry of the Fishguard Volcanic Complex, Wales
Authors: Bevins R. E. 
Published: July 2010

AbstractThe Fishguard Volcanic Complex represents an important volcanic episode which occurred within the Welsh sector of the British Caledonide region during early Ordovkian times. A variety of extrusive and contemporaneous intrusive rocks are present, ranging in composition from basic, through intermediate to acidic. Mineral and whole‐rock chemical analyses have been determined on a representative suite of rocks from the complex and, despite secondary alteration effects, the original tholeiitic characteristics of the suite can be discerned. The variation observed is considered to result largely from low‐pressure crystal fractionation, although the origin of the acidic magma remains speculative in view of subsequent extensive recrystallization. The rocks of the Fishguard Volcanic Complex formed in the Welsh Basin, which has been likened by earlier workers to a marginal basin. Comparison of the geochemical characteristics of the Fishguard Volcanic Complex with that of documented marginal basin rocks appears to favour this contention.
The palynology and provenance of the coal fragments contained in the late‐Pleistocene Lleiniog gravels of Anglesey, North Wales
Authors: Walsh P. T. , Butterworth M. A. , Wright K. 
Published: July 2010

AbstractThe numerous coal clasts in the late‐Pleistocene fluvioglacial Lleiniog Gravels of eastern Anglesey contain a varied assemblage of Westphalian A (and possibly also early Westphalian B) spores. Directional sedimentary structures indicate that the meltwater currents which deposited the gravels came mainly from the north and east, while glacial striae and erratic trains indicate that the parent (? Devensian) glacier flowed from the northeast. Consideration is given to the possibility that the coal clasts were derived from the breaking‐up, fairly locally, of far‐travelled rafts of Coal Measures. It is concluded, however, that the most probable explanation is still Greenly's (1919) postulate that the source is a yet‐to‐be‐identified submarine outcrop situated only a few kilometres northeast of Lleiniog.
Late pleistocene (Devensian) glaciofluvial outwash at Banc‐y‐Warren, near Cardigan (west Wales)
Authors: Allen J. R. L. 
Published: July 2010

AbstractOn the southwest‐facing slopes of a bedrock ridge lying between Cardigan Bay to the north and the Afon Teifi to the south stands a group of hills in which 30‐35 m of cross‐laminated and parallel‐laminated sands with lenticular upward‐fining gravel sequences are overlain by 10‐12 m of gravel in a single foreset bed. The sediments mantle a surface of till sloping gently toward the southwest, were transported toward the southwest (across one margin of the Afon Teifi valley), and were cut by a system of densely arranged conjugate normal faults striking northwest‐southeast.The lenticular gravels and fault system suggest that the deposits accumulated as a glaciofluvial outwash spread, and on top of an ice‐lobe that became isolated in the Teifi valley during the downwasting of a glacier which had occupied Cardigan Bay and much of the country to the south. The large gravel foresets capping the succession are the only indication at Banc‐y‐Warren of the former existence of a lake, but neither a large nor deep body of water need be envisaged.
A new isogon‐cleavage classification and its application to natural and model fold studies
Authors: Treagus Susan H. 
Published: July 2010

AbstractTraditional methods of studying natural folds are reviewed. A new method of describing cleavage attitude in folds is presented; the β plot. The combined graph of dip isogon angle ϕ (Hudleston 1973) and cleavage angle β is proposed as a linked classification of fold and cleavage geometry. Plots of β and βϕ are given for three natural fold examples. The classification is extended to the geometry and strain attitude (βϕ5) of two finite‐element models and the classical folding models. Results are compared and some tentative conclusions drawn on the relationship of cleavage, the XY plane of strain and dip isogons.