bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental investigation of etch pit formation on quartz sand grains
Authors: Wilson P. 
Published: May 2009

SummaryAn experimental investigation into the formation of crystallographically orientated etch pits on quartz sand grains was undertaken. The methods and materials used in the experiments differ considerably from those of other workers in this field. Using natural as opposed to artificial solutions, V-shaped or triangular etch pits as well as rectangular pits have been produced on the quartz grains after time periods of 4 hours and 20 hours. Features of intense surface disintegration have also been recorded. The etch pits are compared to those of natural occurrence on grains from the Millstone Grit (Namurian) sediments and the differences discussed.
Apatite in South Wales anthracite
Authors: Baqri R. , Hodson F. 
Published: May 2009

SummaryCarbonaceous dirt bands containing some 40% hydroxyapatite and 10% kaolinite are recorded from the Hornlo seam of the Brynammon district of the South Wales coalfield with an appreciable areal extension. X.R.D. and some chemical data are recorded. The origin of the deposits is ultimately biogenic, possibly located by the porous environment provided by fusinite; but the immediate cause remains uncertain.
Facies variations in the Devonian limestones of eastern South Devon
Authors: Scrutton Colin T. 
Published: May 2009

SummaryThe Middle and Upper Devonian limestone successions at Torquay and in the Lemon Valley SW of Newton Abbot are described. Lithostratigraphic units are proposed for the Torquay succession. The compositions of the coral faunas in both successions are outlined and contribute, together with the other available faunal evidence, towards a broad internal dating of these limestone sequences. Successions elsewhere in the limestones of eastern South Devon are briefly outlined. On the basis of this evidence facies variations from the margin towards the centre of the carbonate platform in eastern South Devon are demonstrated and interpreted as reflecting the development of barrier reefs along parts at least of the platform margin in Givetian times. The character of the reef-complex, named the Tor Bay Reef-Complex, is briefly compared with Devonian reefs elsewhere.
Controls of copper mineralization at Coniston, English Lake District
Authors: Dagger G. W. 
Published: May 2009

SummaryAnalysis of the fracture pattern in the Coniston area of the Lake District indicates that copper mineralization is localized in a series of fractures produced during the main phase of deformation affecting the Borrowdale Volcanic Series. Three events are recognized on the basis of field and textural evidence obtained from polished sections: an early haematite mineralization, correlated with the low grade regional metamorphism affecting the rocks; the main phase of sulphide mineralization, with zoning, which is correlated with a granite intrusion at depth; and a late renewed movement on the veins, with carbonate mineralization, believed to be related to uplift of the granite.
Mylonitic microstructures and their bearing on the development of mylonites – an example from deformed trondhjemites of the Bergen Arc region, SW Norway
Authors: Sinha Roy S. 
Published: May 2009

SummaryThrust-bound bodies of trondhjemite, showing variable intensity of deformation, contain micro-structural evidences which suggest that the mylonitic fabric in them had developed in stages. An initial shearing stage was followed by a flattening one when the characteristic mylonitic microstructures and banding developed. These stages were punctuated and overlapped by phases of recovery and recrystallization. Mineral parageneses and microstructures indicate that prograde metamorphism and ductile deformation characterize the flattening stage. The origin of mylonite is explained in a scheme of progressive deformation during which planes of maximum shear strain and flattening became almost parallel, so that brittle microstructures were either modified or obliterated by ductile ones. The sequence of microstructural development and mineral redistribution suggest that in mylonite formation mechanical process is accompanied with chemical mobility.
Trilobite traces from the Lower Tremadoc of Tortworth
Authors: Crimes T. P. 
Published: May 2009

SummaryThe ichnogeneric status of trilobite furrows (Cruziana) and resting excavations (Rusophycus) is discussed and the suggestion (Seilacher, 1970) that these two distinct types of trace should be united under the genusCruzianais rejected.
A Palaeocene Foraminiferal assemblage from Halesworth, Suffolk
Authors: Fisher M. J. , Williams G. M. 
Published: May 2009

SummaryAn assemblage of benthonic Foraminiferida of late Palaeocene age is described from subsurface material from Halesworth, Suffolk. Twenty-two species are listed, and are compared with microfaunas which were described by Haynes (1954–8) from the type Thanetian.
The stratigraphical relationships of the earliest monograptidae, and the dimorphograptidae
Authors: Toghill P. 
Published: May 2009

SUMMARYThe earliest monograptids are shown to appear at exactly the same time (base of the vesiculosus Zone in Scotland) as Dimorphograptus and Rhaphidograptus, and the earliest species of these two genera are those with long uniserial portions, the forms wiht shorter uniserial portions appearing in the overlying cyphus Zone. Akidograptus is entirely restricted to the premonograptid beds. One of the earliest monograptids is described as Monograptus cyphus var. praematurus var. nov., which has a distinct and earlier range than M. cyphus s.s. Lapworth.
The Neogene calcalkaline volcanism of Central Anatolia: geochronological data on Kayseri—Nigde area
Authors: Innocenti F. , Mazzuoli R. , Pasquarè G. , Radicati Di Brozolo F. , Villari L. 
Published: May 2009

SummaryThe evolution of Neogene volcanic activity in the Central Taurus is investigated; stratigraphical and radiometric age data from the Ürgüp (Kayseri) basin idicate that volcanism in the area began at least as early as Upper Miocene, lasting up to prehistoric times. The volcanism maintained throughout this time interval a calcalkaline character. The diachronous end of calcalkaline volcanism along the Taurus margin is tentatively related to the differential collision between the Afro-Arabian and the Anatolian plates, probably due to an original irregular shape of the Anatolian continental margin.
Coral patch reefs in the Bajocian (Middle Jurassic) of Lorraine
Authors: Hallam A. 
Published: May 2009

SummaryAn account is given of coral patch reefs in the Bajocian of Lorraine, France, and a distinctive ecological association in the other invertebrate fauna recognized, which compares closely with that present in the late Oxfordian reef facies of southern England. The inference is made of a series of low mounds on the original sea bed, composed of coralline sheet structures interfingering with calcareous sediment which locally and periodically enveloped the coral colonies. Compared with Recent patch reefs in the Bahamas and around Bermuda, important differences can be inferred for the Jurassic structures, principally the lack of significant topographic relief, major internal cavities, erosion and algal incrustation.
Structures in the lawsonite—glaucophane schists of New Caledonia
Authors: Lillie A. R. 
Published: May 2009

SummaryThe regional strike of the bedding and foliation is NW but most of the folds and lineations plunge roughly SW. Lineations that resemble grain (longrain) seem to be usually parallel to the steeply plunging fold axes. This structural pattern occupies more than 2,000 km2. The formation of this pattern of folds was preceded and succeeded by regional folding along horizontal axes.
Pedogenic carbonates and flood sediment accretion rates: a quantitative model for alluvial arid-zone lithofacies
Authors: Leeder M. R. 
Published: May 2009

SummaryA general model for pedogenic carbonate development in alluvial sediments is based upon of rates flood sediment accretion versus time taken for particular carbonate profiles to develop. Conclusions regarding rates of Holocene carbonate pedogenesis and the changing morphology and thicknesses of carbonate profiles with time are used to predict critical values of floodbasin accretion rates which would have enabled particular ancient profiles to develop. Local (intra-drainage basin) and regional profiles are separated and a number of models for calcrete genesis are outlined. The presence or absence of particular genetic stages of calcrete may be used as a rough guide to estimate ancient floodbasin accretion rates.
Underwater studies of recent lava flows around São Miguel (Azores)
Authors: Mapstone N. B. , Rood A. P. , Jackson N. G. 
Published: May 2009

SummaryAn underwater study of recent submarine lava flows on São Miguel (Azores) suggests that the island has subsided by as much as 9 m relative to sea level over the last few thousand years. A spectacular system of overlapping lava arch structures occur immediately below the ancient sea level, and they are thought to have formed when tongues of molten lava flowed over a steep autochthonous submarine scree slope. The scree was subsequently removed by strong longshore currents and wave action.
Trilobite traces and the age of the lowest part of the Ordovician reference section for NW Spain
Authors: Crimes T. P. , Marcos A. 
Published: May 2009

SummaryA quartzite-shale sequence forming the lowest part of the Ordovician reference section for NW Spain in the Cantabrian zone at Cabo Peñas, lacks body fossils and has hitherto been of uncertain age. This sequence has, however, yielded a variety of trilobite-produced trace fossils. The lowest exposed beds haveCruziana breadstoniandRusophycussp. while a few tens of metres higherC. furcifera, C. goldfussi, C. rugosaandRusophycus asturiensissp.nov., are also present. The highest beds have yielded onlyC. furcifera. The traces suggest that while the top of the sequence is at least as high as Arenig the lowest beds are of Tremadoc (post-Dictyonema flabelliformeZone) age. This implies a thickness for the Arenig of no more than 400 m and probably considerably less. In contrast, thicknesses in excess of 1000 m occur to the W in the West Asturian–Leonese Zone. This, together with evidence of tidal to intertidal deposition at Cabo Peñas, tends to confirm that the area was the shelf to an Ordovician trough situated in the West Asturian–Leonese zone.
The charnockite series of Amaravathi, Gunter District, Andhra Pradesh, South India
Authors: Ramaswamy A. , Murty M. S. 
Published: May 2009

SummaryThe charnockite series consisting of pyroxene granulites and charnockites are not formed by magmatic differentiation, although both units had their antecedents in igneous material. The solid-state recrystallization of pyroxene granulite and the liquid-state crystallization of charnockite are inferred from the field criteria. The pyroxene granulites with the associated paragneisses are formed from the original sedimentary-volcanic sequence under granulite facies of metamorphism. The magmatic charnockites emplaced into these rocks resulting in the development of intermediate varieties by the partial assimilation and incorporation of the pyroxene granulites. The stability of the minerals is not affected by this migmatization, which is therefore thought to have taken place under granulite facies conditions. The evolutionary trend of the charnockite series is one of retrogression from the earlier granulite facies to the later almandine-amphibolite facies, caused by the subsequent granite invasion.
An Ophiceratid ammonoid from the New Zealand Permian and its implications for the Permian–Triassic boundary
Authors: Waterhouse J. B. 
Published: May 2009

SummaryA nesw Ophiceratid genus and species Durvilleoceras woodmani is described from the late Middle Permian Greville Formation of New Zealand, with Episageceras aff noetlingi Haniel. The horizon is close in age to the Kathwai dolomite of the Salt Range, which also has a mid-Permian Ophiceratid species, Ophiceras connectens Schindewolf. The occurrence of these two species shows that the Ophiceratidae cannot serve as an index of early Triassic rocks. The so-called basal Triassic Griesbachian Stage may prove to be closely linked to the Permian period. The key Griesbachian ammonoid genus Otoceras is related to Permian genera, with no later survivors. Moreover the widespread occurrence of Permian-type Productacea and other brachiopods in beds of the Griesbachian Stage in North America and Himalayas also suggests that the Griesbachian is Permian rather than Triassic. To judge from faunas, the start of the Triassic could be based on the incoming of numerous ammonoid families and Triassic brachiopods in the Smithian Stage. The intervening Dienerian Stage between the Griesbachian and Smithian stages is relatively barren of faunas, reflecting some sort of catastrophe at the end of the Paleozoic Era, but has mainly Permian survivors. Such a picture of the Paleozoic–Mesozoic boundary conforms with the intention if not the practice of early paleontologists.
Basic magmatism in relation to metamorphism and orogeny in Guiana: a speculation
Authors: Choudhuri A. 
Published: May 2009

SummaryThe northern part of the Guiana Shield consists of large tracts of basic and intermediate volcanic rocks and sediments which are thought to have formed under geosynclinal conditions. During the 2000 m.y. Trans-Amazonian Orogeny these rocks were subjected to tectonism and metamorphism resulting in a broad belt of green schist facies with local and isolated patches of high grade metamorphic rocks and gneiss complexes. In the early stages of orogeny during which folding and probable block faulting of the sediments and volcanics took place, these rocks were intruded by basic and ultra-basic rocks giving rise to metagabbro-amphibolite-peridotite associations, commonly in the areas of subsequent high-grade metamorphism. In an attempt to account for the frequent supply of basic magma during and after the orogeny it is postulated that mantle peridotites rose diapir-like below the sinking geosyncline, and by partial melting not only provided basic magmas but also thermal energy which spread upwards to metamorphose the already tectonized crustal rocks; recent gravity measurements indicate an upwarped ‘sima’ under the Bartica Assemblage gneiss complex.
Petrological Evidence for the Presence of Amphibole in the Upper Mantle and its Petrogenetic and Geophysical Implications
Authors: Oxburgh E. R. 
Published: May 2009

AbstractIn addition to meeting various geophysical requirements, an ultrabasic upper mantle must provide a source both for olivine nodules and for the range of “primary” basaltic types, i.e. those which are apparently uncontaminated and undifferentiated. Potassium abundances and other considerations suggest that olivine nodules represent upper mantle which has previously yielded basalt by partial fusion but is now “barren”, principally because of potassium depletion, and is unable to yield more. The possible range of potassium contents of “parent” upper mantle (still able to yield basalt) is considered and it is argued that at any concentration within this range, the potassium is not distributed between the main mantle phases as a trace component but is contained largely within a potassium-rich minor phase. It is shown that this phase is probably an amphibole and may make up between 2 and 20 wt. per cent of parent upper mantle. In addition to the isochemical phase changes to be expected with increasing depth, a transition is proposed from an upper zone of amphibole-free (barren) upper mantle to a lower zone of amphibole-bearing (parent) upper mantle. The petrogenetic and geophysical implications of such a model are discussed; in particular it provides a possible explanation for the Gutenberg low-velocity zone.
A Seismic Refraction Section of the Preglacial Teifi Valley near Cenarth
Authors: Francis T. J. G. 
Published: May 2009

AbstractA short seismic refraction line has been shot just north of Cenarth in Cardiganshire across the preglacial valley of the River Teifi. The deepest point on the Ordovician basement has been found to be 30 feet below O.D.
A Simple Grid Deviation Technique of Study of the Areal Composition Variations in Granitic Bodies
Authors: Saha Ajit Kumar 
Published: May 2009

AbstractA method of preparing grid deviation maps for the representation of the areal composition variations in granitic bodies is described. A comparative study of this method and the trend surface method by using the data of forty-five modal analyses of Bahalda hornblende granodiorite indicates greater effectiveness of the former in several respects.
Siderite- and Calcite-bearing Concretionary Nodules in the Lias of Yorkshire
Authors: Hallam A. 
Published: May 2009

AbstractNodules containing siderite and calcite in the Yorkshire Lias have been studied quantitatively using petrographic, X-ray and chemical methods. Ankerite is recorded from the Lias for the first time. It is shown how the relative abundance of early diagenetic siderite and calcite correlates with sandiness of the sediment and provides an index of environmental change.
A New Interpretation of the Llandovery Sequence of North Connemara, Eire
Authors: Piper David J. W. 
Published: May 2009

AbstractThe historical development of the stratigraphic nomenclature of the Llandovery of north Connemara is described. The lowest beds are red sandstones and interbedding keratophyre passing up into a complex sequence of grey, green and red clastics with shelly facies fossils. Above this are red and green mudstones and siltstones with rare graptolites. In the east these are overlain by coarse sandstones and conglomerates. The conglomerates are probably allochthonous. In the west this coarse facies is developed earlier and laterally interfingers with the shelly facies clastics and overlying mudstones. The sub-Wenlock unconformity reported by McKerrow and Campbell from this region is reinterpreted as an appearance of this interfingering.
Belemnite Deformation at Fernigen, Switzerland
Authors: Johnson M. R. W. 
Published: May 2009

AbstractElongated belemnites illustrated by Albert and Arnold Heim were not deformed as brittle bodies, because the guards have undergone recrystallization. A tentative hypothesis is put forward to integrate the mechanical and chemical processes in the belemnites. During progressive extension of the belemnites carbonate material has diffused from highly stressed fragments of the guards into “low-stress” spaces between the fragments.
A Sagitta Zone Conodont Fauna from the Wenlockian of the Usk Inlier, Monmouthshire
Authors: Austin R. L. , Bassett M. G. 
Published: May 2009

AbstractA conodont fauna from a thin limestone bed, considered to be of Wenlockian age, in the Usk inlier, Monmouthshire, is described. Ninety-seven specimens are assigned to four genera and eight species. The fauna is referable to the sagitta conodont zone and suggested correlations are made with the upper part of the Ostra-coden-Kalkes in Germany, with part of the Aulacopleura Schichten and Kok-Kalk in Austria, and with part of the Lockport Dolomite and Rochester Shale in North America.
Psigraptus, a New Graptolite Genus from the Tremadocian of Yukon, Canada
Authors: Jackson D. E. 
Published: May 2009

AbstractThe new genus, Psigraptus, containing P. arcticus n. sp. and genotype and P. lenzi is proposed for two-branched and three-branched reclined graptolites with isolate autothecae. The genus is known only from the Bryograptus-Clonograptus Zone (Tremadocian), Yukon Territory.
Fabric Analysis of a Deformed Vein
Authors: Nettle J. T. 
Published: May 2009

AbstractThe crystallographic orientation of optic axes, the crystallographic orientation of {0112} twins and the dimensional orientation of calcite from a drag folded vein are described. The external movements that have caused the deformation of the vein are interpreted and the fabric characteristics are related to them. The calcite fabric shows a marked similarity to those which have been produced experimentally. An analysis of the quartz fabrics demonstrates that there is no significant preferred orientation of optic axes.
Some Effects of Palaeozoic Folding on the Pre-Cambrian Rocks of the Frenchmans Cap Area, Tasmania
Authors: Spry A. , Gee D. 
Published: May 2009

AbstractSmall–scale isoclinal folds in Pre–Cambrian schists and quartzites near Frenchmans Cap, Tasmania, were formed during the Pre–Cambrian Frenchman Orogeny but the large open folds were produced during the Devonian Tabberabberan Orogeny. The Mary Antiform (Devonian) at the Raglan Range can be “unrolled” to leave the foliations almost horizontal, indicating that the isoclinal folds were recumbent prior to the Palaeozoic.
Studies in North Atlantic Geology and Palaeontology: 1. Upper Cretaceous
Authors: Funnell B. M. 
Published: May 2009

AbstractAn Upper Maastrichtian assemblage of planktonic foraminifera is recorded from chalk dredged from Galicia Bank, a non–magnetic seamount off the west coast of Spain. The occurrence and distribution of Upper Cretaceous sediments and fossils in the North Atlantic is reviewed, and their significance for the palaeogeography of the North Atlantic during the Upper Cretaceous is considered.
Boudinage-type Structures at Sørfinnset, Gildeskaal, North Norway
Authors: Bradshaw R. , Wells M. K. 
Published: May 2009

AbstractA layer of massive and lineated hornblende-biotite-gneiss has fractured along ac-joints (perpendicular to the layering and b–lineation), at regular intervals along its lower surface in contact with a thin marble bed. The joints have been opened from below and the marble has penetrated upwards to form intrusive tongues caused by extremely plastic flow folding, as shown by the unbroken banding in the marble. The structure constitutes a variety of one-sided boudinage involving segmentation in the lowest metre or so of the hornblendic rock, while the extreme marble deformation is all accommodated in a few centimetres thickness. The structures must have developed at relatively high temperatures to allow contemporaneous segregation of quartz-feldspar pegmatite veins from the hornblendic rock, and of diopside reaction skarns at the marble junctions.
The Highland Boundary Fault in East Tyrone
Authors: Cobbing E. J. 
Published: May 2009

AbstractCorrelation of the metamorphic inlier of Co. Tyrone with the Connemara Schists, together with a reinterpretation of the"Tyrone Igneous Series" erected by J. J. Hartley, lends support to recent suggestions that the Highland Boundary Fault originated as a normal fault with downthrow to the north. The palaeogeographical implications of this are briefly discussed.
The Formation of Tension Joints in Sedimentary Rocks: An Explanation
Authors: Hobbs D. W. 
Published: May 2009

AbstractA simple theoretical explanation is given for the formation of systematic tension joints in sedimentary rocks. This theory shows that the frequency of occurrence of joints in a bed of rock is dependent upon the physical properties of the rock bed, the physical properties of the surrounding rock beds, the thickness of the rock bed, and the degree of tectonic deformation.
Further Evidence for a Middle Würm Interstadial and a Main Würm Glaciation of South-west Wales
Authors: John Brian S. 
Published: May 2009

AbstractAt Cil-maenllwyd (Cardiganshire) glacial outwash sands were found to contain layers of small wood fragments. A radiocarbon age determination of 33,750 yrs B.P. indicates that the wood fragments are probably of Middle Würm age, and that the last glaciation of St. George's Channel occurred during the Main Würm. Pollen and spores contained in the sands suggest that the environment prior to the last glaciation was at one stage predominantly forested. The organic remains are thought to relate to the problematical “ Middle Würm Interstadial ”, rather than the Paudorf Interstadial.