bluuebunny/crossref_metadata_2025_split huggingface dataset:
The age of the Whin Sill
Authors: Fitch F. J. , Miller J. A. 
Published: July 2010

AbstractThe Whin Sill and its related dykes are intruded into Carboniferous strata in the North of England. Together they form a distinct petrographical province in which basic magmatism appears to have been closely related to a single phase in the structural history of the area. The relevant stratigraphical, structural and isotopic evidence suggests to the authors that the Whin Sill suite was intruded during the Stephanian, around 295 ± 6 m.y. This conclusion is supported by twenty‐one new potassium‐argon age determinations accompanied by a petrographical study of the factors which cause discrepancy in isotopic results from Whin Sill rocks.
The metamorphic rocks of the southern part of the Mainland of Shetland
Authors: Flinn Derek 
Published: July 2010

AbstractThe paper presents a one mile to the inch geological map of the southern part of the Mainland of Shetland (excluding areas underlain by Old Red rocks) and an account of the metamorphic rocks occurring there.The metasediments mostly belong to the East Mainland Succession which is about 14 km thick. They dip vertically and strike north‐south. The metasediments in the west were originally laminated sandstones devoid of current bedding and grading and composed of poorly weathered material. They include several limestones up to half a kilometer thick. In the east the metasediments were originally gritty quartzites and sandstones together with shales which are usually finer grained and composed of more weathered material than those to the west. On two occasions the deposition of these rocks was interrupted by outpourings of spilites.The rocks show signs of four metamorphisms. The first metamorphism was accompanied by a penetrative deformation causing elongation of the rocks in a north‐south direction, shortening in an east‐west direction and elongation and shortening in different areas in a vertical direction. As a result of this metamorphism the pelitic rocks over the whole area became schists containing such minerals as biotite, chlorite, muscovite, quartz and feldspar, and possibly garnet. In a later metamorphism a belt of these rocks a kilometer or so wide became gneissified, probably due to the passage of high temperature fluids. In various parts of the area such minerals as biotite, chlorite, garnet, staurolite, chloritoid, and kyanite grew as porphyroblasts in a series of episodes referred to collectively as the porphyroblast metamorphism. After these metamorphisms the area was intruded, 400 m.y. ago, by a number of granites. In places these have produced extensive thermal aureoles containing such minerals as staurolite, chloritoid, andalusite, kyanite, sillimanite, garnet, muscovite, biotite and chlorite in pelitic rocks. The emplacement of one of the granites was accompanied by large and small scale folding.Several major faults are described including the Nesting tear fault with a 16 km dextral displacement and a mélange zone beneath a nappe.
The source of ferroan and non‐ferroan calcite cements in the Halkin and Wenlock Limestones
Authors: Oldershaw A. E. , Scoffin T. P. 
Published: July 2010

AbstractAn early and a late calcite cernent are distinguished in limestones of Carboniferous age in N. Wales and Silurian age in Shropshire, England. Solution of aragonite, and preferential pressure solution of carbonate grains in day‐rich beds are considered to be the sources of the early and late cements, respectively. An association between the distribution of ferroan calcite and clay minerals indicates that clays may be an important contributor of iron during the precipitation of the late cernent.
Stratigraphy and geological history of the Malvern, Abberley and Ledbury Hills
Authors: Phipps C. B. , Reeve F. A. E. 
Published: July 2010

AbstractA revised stratigraphy of the Malvern, Abberley and Ledbury Hills is given. The Silurian succession is considered in detail and shows a series of five major sedimentary rhythms or cycles between an initial Llandovery transgression and regression at the close of the Silurian period. The succession exhibits an alternation of shale with either limestones and/or terrigenous clastics, and the rhythmic nature of the sequence suggests a periodic change in base level. A number of different lithological facies can be distinguished in the limestone formations, particularly in the Wenlock limestone. A detailed faunal list is given for most of the Silurian sequence. From the evidence of the stratigraphic succession, an attempt has been made to decipher the complex geological history of the area.
Succession and structure in the Llwyd Mawr Syncline, Caernarvonshire north Wales
Authors: Roberts Brinley 
Published: July 2010

AbstractA succession of strata ranging in age from Upper Cambrian to Valentian is described. They occupy ground in, and adjacent to, the Llwyd Mawr syncline. Most of the rocks are marine but during mid‐Caradocian (Soudleyan) times a rhyolitic ignimbrite sheet was emplaced and rests disconformably on Llanvirn slates. It has a remanant thickness of 2300 ft and is a single cooling unit. A second volcanic episode (Lower Longvillian) produced 600 ft of bedded pyroclastic rocks with only subordinate ignimbrites. Mid‐Caradocian minor intrusions of rhyolite occur as domes and sills in association with the volcanic rocks. Minor intrusions of dolerite and micro‐tonalite are probably of Caledonian age.Three phases of movement are recognized within the main end‐Silurian Caledonian movements. The first movement phase, F1, produced the main fold architecture and the dominant associated axial‐planar cleavage, S1. The folds, which possess a Caledonoid trend, usually stand vertically, but rarely they verge slightly to the southeast. They are periclinal in style. The second movement phase, F2, was weak and produced a sporadically distributed set of open folds and associated axial‐planar crenulation cleavage, S2, of Caledonoid strike. The axial‐planes dip gently to the southeast quadrant. Folds of the third movement phase, F3, plunge northwest and the associated axial‐planar crenulation cleavage, S3, dips steeply to the northeast. The F3 folds produce a pronounced arcuation in the trace of the Fl structures from an azimuth of 60° in the northwest to 10° in the south of the area.
Sedentary kaolinitic soil on the carboniferous limestone series in anglesey
Authors: Ball D. F. , Mew G. 
Published: July 2010

AbstractA soil overlying Carboniferous calcarenites in Anglesey has a clay fraction dominantly of kaolinite in contrast to the illite‐chlorite assemblages generally characteristic of North Wales soils. From the mineralogy and field evidence this soil is interpreted as resulting from Late Glacial in situ weathering of the underlying rocks.
A volcanic vent in the tremadocian rocks southeast of Blaenau ffestiniog, Merionethshire, North Wales
Authors: Bromley Alan V. 
Published: July 2010

AbstractA tuff filled volcanic vent which outcrops among Tremadocian rocks about 2 miles southwest of Blaenau Ffestiniog is described. The vent is correlated with the lower Caradocian Moelwyn Volcanic Series. Comparisons are drawn between this vent and the fissures from which the dominantly ignimbritic rocks of the Snowdon Volcanic Series were erupted and these are extended to account for lithological differences between the Snowdon and Moelwyn volcanic rocks.
Conical folding and fracture patterns in the pre‐betic of Southeast Spain
Authors: Moseley F. 
Published: July 2010

AbstractThe Pre‐Betic Alpine ranges of southeast Spain consist of a series of ENE trending folds developed mostly in Mesozoic and Tertiary limestones. One of these folds, the Mongo Syncline is described here and is of interest because of firstly its anomalous ESE trend, secondly the clearly demonstrable conical form and thirdly the en‐echelon arrangement of the minor fold axes which comprise the axial zone of the main syncline. To facilitate interpretation of this structure a considerable number of bedding and fracture orientations were taken (the latter mostly joints) over an area of 3 sq. km. The fractures related to the structure of the syncline, reveal particularly important sets of ENE “sinistral” joints and northerly “dextral” joints. The origin of the fold is debatable but the interpretation favoured here is that of a second order drag fold to a major wrench fault in the pre‐Triassic basement. In both cases diapiric squeezing of the incompetent Trias, which outcrops as an elongated (NW‐SE) inlier adjacent to the Mongo structure is envisaged.
A fabric analysis of the ground moraine deposits of the lleyn Peninsula of Southwest Caernarvonshire
Authors: Saunders G. E. 
Published: July 2010

AbstractAn analysis of the preferred orientation of the long axes of erratics contained within the superficial deposits of the Lleyn Peninsula indicates that during the two recorded glacial advances the area was invaded by ice from two source regions—the Irish Sea ice‐sheet and local Welsh ice‐bodies. An attempt is made to re‐construct the pattern of ice movement during both glacial advances, to determine the extent to which ice from each source region penetrated Lleyn, and to interpret the environment under which the tills were deposited.
The origin and development of kink‐bands in a foliated body
Authors: Dewey J. F. 
Published: July 2010

AbstractAlthough the deformation of foliated rocks by kink and glide mechanisms has been studied in detail in recent years, fundamental differences of opinion have emerged, particularly as a result of experimental work. Most theories concerning the relationship of kink‐bands to stress‐fields are empirically based. Evidence on whether kink‐bands are the result of a shear couple and on limiting factors for external rotation is presented. It is concluded that kink‐bands are zones of externally rotated foliation bounded by kink‐planes which develop parallel to planes of high shearing stress at infinitesimal strain.
Facies change in upper devonian and lower carboniferous rocks of Southern Ireland
Authors: Naylor D. 
Published: July 2010

AbstractIn south‐west Ireland 8,000 ft (2,440 m) of marine sandstones and mudstones, the Cork Beds (?Upper Famennian to E Zone, Carboniferous, in age), overlie the Old Red Sandstone. Farther north the Old Red Sandstone is succeeded by thin Lower Limestone Shales overlain by thick Waulsortian bank limestones.A critical section (North Ringabella) west of Cork Harbour, in which 6,500 ft (1,981 m) of Old Red Sandstone and Cork Beds is exposed, is described and divided into ten formations. By comparison with sections to the south the upper beds of the Old Red Sandstone are shown to pass southward into marine sandstones (Cork Beds) of ?Upper Famennian age. The successions in the Cloyne and Cork Synclines are described and reveal the progressive northward change in the Lower Carboniferous from the argillaceous Cork Facies through a zone of isolated bank limestones (Cloyne) to a thick, 4,000 ft (1,219 m), Waulsortian bank complex (Cork). Finally an attempt is made with use of isopachyte maps to reconstruct the palaeogeography of southern Ireland in Upper Devonian and Lower Carboniferous times.
Trace fossils from the cambro‐ordovician rocks of North Wales and their stratigraphic significance
Authors: Crimes T. P. 
Published: July 2010

AbstractIn North Wales, Cruziana semplicata (Salter) is recorded from three otherwise unfossiliferous localities and Teichichnus sp. (Seilacher) and Phycodes circinatum (Richter) are shown to be widely distributed within the lower Arenig (Didymograptus extensus zone) sediments. P. circinatum is also recorded from the otherwise unfossiliferous Upper Pennant Quartzite. From a discussion of the stratigraphic ranges of these trace fossils it is suggested that the rocks of the C. semplicata bearing localites are Upper Cambrian (Ffestiniog) in age while the Upper Pennant Quartzite is Ordovician, probably Arenig.
Hornblende, gabbros and picrites at Rhiw, Caernarvonshire
Authors: Hawkins T. R. W. 
Published: July 2010

AbstractThree hornblende‐bearing intrusive masses consisting mainly of cumulate rocks derived from a water‐rich, alkali‐basalt magma are described. They probably all belong to one Lower Palaeozoic 'sill‐like' intrusion with an original sloping floor. The sequence is divided into nine zones, and three major, and numerous minor units are recognized. Deuteric activity produced important alteration sequences, while Caledonian regional metamorphism only caused substantial alteration to the mineralogy in the marginal zones of the intrusion.
Hydrocarbon‐bearing nodules from Heysham, Lancashire
Authors: Harrison R. K. 
Published: July 2010

AbstractNodules enriched in hydrocarbon occur sparingly in a subarkose bed of Namurian (?Kinders‐coutian) age near Heysham, Lancashire. The nodules are commonly spheroidal to ellipsoidal (1‐9 cm across) and are composed of alternating shells of hydrocarbon‐rich and hydrocarbon‐poor sandstone. Irregular impregnations and pellets are also formed from hydrocarbon. The hydrocarbon is infusible, insoluble in CCl4, CS2 and petroleum naphtha, and is classified as a pyrobitumen. Ash content averages 22.1% and the ash contains major V; subordinate Fe, U, Ca; minor Pb, Ti; traces of Ba, Mn, Zr, Ga, Y, Sr, Ni and Th. Sulphide inclusions in the hydrocarbon are comprised of chalcopyrite and pyrite. Hydrocarbon, commonly with illite, replaces primary sandstone matrix and clastic grains. The nodules may have formed as periodic structures (cf. Liesegang rings) with precipitation from thixotropic hydrocarbon compounds. The available evidence is insufficient, however, to postulate with any certainty the origin of the hydrocarbon. It may have formed syngenetic accretions with clastic detritus or alternatively it may have been introduced after deposition of the sandstone, although no feeders have been observed.
Structures of the Skiddaw Slates in the Caldew Valley, Cumberland
Authors: Roberts D. E. 
Published: July 2010

AbstractThe hornfelsed Skiddaw Slates in the River Caldew, Cumberland, exhibit one of the best displayed sets of folds in the country. Patterns resulting from an analysis of these folds and the structures on the valley sides, indicate that the rocks have suffered several phases of deformation. Evidence is produced to suggest that folding was initiated during the pre‐Bala movements, and re‐folding occurred during the main end‐Silurian orogeny. During the end‐Silurian movements, folding due to collapse under gravity also occurred.
The exposures of Ludlow rocks and associated beds at Tites Point and near Newnham, Gloucestershire
Authors: Cave R. , White D. E. 
Published: July 2010

AbstractThe Leintwardine and Whitcliffe Beds of the Ludlow Series outcropping at Tites Point and near Newnham, Gloucestershire, are described and compared with similar beds exposed at May Hill. Data from the Brookend Borehole, 1 ½ miles (2.41 km) south of Tites Point, reveal that southward thickening affects all subdivisions of the Ludlow Series. The occurrence of the Ludlow Bone Bed in the Tites Point outcrop is also recorded.
The Carboniferous Limestone of Chipping Sodbury and Wick, Gloucestershire
Authors: Murray J. W. , Wright C. A. 
Published: July 2010

AbstractThe rock types and successions encountered at two localities have been described and interpretated with reference to modern analogues. In the Clifton Down Limestone a cycle of sedimentation is recognised passing from intertidal algal mats, through lagoons, barrier and open shelf deposits and back through the same sequence to intertidal algal mats.
The structures of the Ardsheal Peninsula, Argyll, their age and regional significance
Authors: Treagus J. E. , Treagus S. H. 
Published: July 2010

AbstractThe lithologies and structures of the Dalradian rocks of the Ardsheal Peninsula, Argyllshire are described. The structures associated with the main synformal fold (part of the Appin Syncline) are shown to be F1 in age. F2 structures cross the Syncline and show progressive development towards the east. The Syncline is correlated and compared with other major F1 folds in the region. This interpretation is contrasted with other interpretations of the Syncline as a third‐phase structure which can be correlated with late‐phase folds in the Dalradian.
Remains of pingos in Wales and the Isle of Man
Authors: Watson E. 
Published: July 2010

AbstractRemains of pingos have already been reported from east central Wales. This paper records a further group from west central Wales and a probable group from the Isle of Man. When they are compared with contemporary pingos it is clear that they belong to the open system type, which, in contrast with the solitary pingo of the closed system type, tends to occur in clusters of mutually interfering forms and on melting to result in a complex pattern of ramparts.Much of the recently discovered group in central Wales shows this complexity and suggests later pingos developing on the sites of earlier ones as the injection centres migrated upslope. On more open sites simpler solitary pingos occur, including some elongated forms. The Isle of Man group consists of depressions without ramparts but their location and orientation suggest they represent pingo basins. It is argued that although the most convincing evidence for pingos consists of arcuate to annular ramparts enclosing basins, the ramparts may disappear through cultivation.
Melting relations of some ultra alkali volcanics
Authors: Tilley C. E. , Thompson R. N. 
Published: July 2010

AbstractThe melting relations of a group of ultra alkali lavas are determined. They include a range of types rich in melilite and nepheline (melilite nephelinites) from the Nyiragongo volcano of the Congo and a group rich in olivine (olivine nephelinites).The liquidi of these assemblages range from 1100°C (the melilite nephelinite of the lava lake of Nyiragongo) through the Cameroons etindite (clinopyroxene nephelinite, 1118°C to 1300°C for the olivine nephelinites.For the most part the liquidi follow a course dependent on iron‐enrichmcnt. Notable departures are examples rich in leucite.
A British meta‐anthracitic coal of Devonian age
Authors: Cook A. C. , Murchison D. G. , Scott E. 
Published: July 2010

AbstractVitrinite from the Devonian Gramscatho Beds at Pendower in southwestern Cornwall displays optical properties which indicate an extremely high rank (meta‐anthracite). Despite this high rank, wood structures are clearly evident in polished sections between crossed polars. Some coke is present and this feature, together with the optical properties of the main vitrinite mass, suggests that relatively high temperatures (probably in excess of 350°C), were associated with the metamorphism of the host rocks. Reflectivity measurements on oriented blocks show that the vitrinite is optically biaxial, which conflicts with the widely accepted view that vitrinites are negative uniaxial materials.
Tectonically dewatered slates in the Ludlovian of the Lake District, England
Authors: Mca. Powell C. 
Published: July 2010

AbstractMultiple siltstone dykes intruded parallel to cleavage in the Ludlovian argillites and graywackes of the Lake District throw new light on the origin of slaty cleavage. Pore pressures equalling lithostatic pressure developed during the Caledonian orogeny and caused tectonic dewatering of the partially lithified sediments. Slaty cleavage was initiated as an essentially planar structure by the intrusion of thin pelitic folia during the escape of the pore water. Cleavage folia and fold axial planes may have a common geometric relationship to the deforming stresses, but are independent of each other in origin. Continued deformation after tectonic dewatering refracted the cleavage by rotation of competent layers. Critical examination of evidence supporting traditional theories of slaty‐cleavage formation shows that all observed relationships are compatible with the tectonic‐dewatering theory.
On the age of the Hoxnian interglacial
Authors: Page N. R. 
Published: July 2010

AbstractFifteen new radiocarbon datings from British Pleistocene deposits are described. The datings are related to the classic Pleistocene succession and shown to be consistent with the stratigraphic sequence of East Anglia. On the basis of these datings, an absolute chronology is developed. According to this chronology, the glacial drifts of East Anglia ought to postdate 40,000 B.P. and hence belong to the Last Glaciation of the British Isles. The Hoxnian interglacial of this chronology is dated between about 25,500‐21,000 B.P. The conventional age for the Hoxnian interglacial is 175,000–120,000 B.P. The validity of the radiocarbon datings is considered and some of the implications and problems of a revised age for the Hoxnian interglacial are reviewed.
A preliminary study of the structure, stratigraphy and metamorphism of some contact rocks of the western Andes, near the Quebrada Venado Muerto, Peru
Authors: Atherton M. P. , Brenchley P. J. 
Published: July 2010

AbstractThe sequence and structure of the volcanic rocks of a small area lying within the main belt of plutons of the Peruvian Andes were mapped and are here described. Metamorphic zoning of the calcareous aureole minerals was shown to be similar to that described elsewhere, e.g. wollastonite, diopside, hornblende with increasing distance from the contact. The mineral assemblages and their spatial and textural character indicate rapid heating of the aureole, with only a short time at maximum temperatures. The complex mineralogy in individual rocks is interpreted in terms of changing physical conditions during the thermal event. The sequential assemblages are the result of changes in activity of CO2, H2O and Fe3+ in particular.
Facies and faunal changes in the Ludlovian rocks of Aymestrey, Herefordshire
Authors: Lawson J. D. 
Published: July 2010

AbstractThe Aymestrey area displays changes in facies, faunas and thicknesses which can be related to its position on the shelf edge during later Silurian times. The Wenlock Limestone becomes an alternation of limestones and mudstones. The Lower and Middle Elton Beds, however, are substantially similar to their development at Ludlow. The Upper Elton Beds and the Bringewood Beds thin westwards within the area, probably due to non‐deposition or erosion on a ridge at the hinge between shelf and basin. The most striking change is the rapid westward passage of the Aymestry Limestone facies of the Upper Bringewood Beds into siltstones, which are considered to be shallow‐water deposits and not basinal. The Leintwardine Beds exhibit a westward thickening, and slumping is developed in the Lower Leintwardine Beds; the faunas relate more to the basin facies than to the shelf. The Whitcliffe Beds thicken markedly westwards but retain their shallow‐water characteristics.
Sorting of bivalve populations in a beach environment
Authors: Trewin N. H. 
Published: July 2010

AbstractSize sorting of shells and valves of transported death assemblages of Mytilus edulis is shown to have taken place, and greatly affected size‐frequency distributions of shell accumulations deposited in a beach environment. Selective transport and deposition of different size grades gives histograms which may be strongly skewed or multimodal, and include numerous small shells. The usually predicted bell‐shaped distributions for sorted assemblages are not always produced. Little evidence of growth and mortality rates can be deduced with confidence from the transported assemblages.