bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ordovician Bryozoan (Ectoproct) Diplotrypa from Central Burma
Authors: Maw U Ba , San U Bo , Ross J. R. P. , Ciochon R. L. 
Published: May 2009

SummaryNew stratigraphic data for the Ordovician ectoproct Diplotrypa cf. D. westoni in the Shan Plateau region of Central Burma indicates correlation with the Trentonian of New York State.
The composition and age of basalts dredged from the Blackstones igneous centre, western Scotland
Authors: Mitchell J. G. , Jones E. J. W. , Jones G. T. 
Published: May 2009

SummaryA collection of basaltic rocks has been dredged from part of the Blackstones igneous centre, a major offshore intrusion situated about 50 km SW of Mull. The basalts are mainly olivine tholeiites and are closely similar to transitional basalts found on the Inner Hebrides. The mean of four concordant K—Ar dates obtained from the lavas indicates an age of 57.1 (± 0.9) Ma. The Blackstones complex thus appears to be coeval with other Tertiary centres of the area.
A probable glacio-marine deposit of Late Ordovician—Early Silurian age from the north central Newfoundland Appalachian Belt
Authors: McCann A. M. , Kennedy M. J. 
Published: May 2009

SummaryConglomerate beds occur in an Upper Ordovician—Lower Silurian clastic sequence on the northeastern side of the Newfoundland Central Paleozoic Mobile Belt. They contain scattered pebbles and cobbles dispersed in a finely laminated sandstone and siltstone matrix. Laminations are generally 5–20 mm thick and the clasts 10–300 mm across. The laminations are locally disrupted by the clasts. These laminations have subsequently been tectonically flattened into augen around the clasts and locally disrupted by boudinage. It is concluded that these conglomerate beds represent icerafted glacio-marine deposits interbedded with turbidites which were probably deposited in a locally restricted marine environment. The deposits are interpreted on the basis of scattered fossil localities as being of Late Ordovician–Early Silurian age. They are compared with deposits of similar age elsewhere in the North Atlantic region.
Hornblende–garnet Granulites from Hatton, Ceylon
Authors: Cooray P. G. 
Published: May 2009

SummaryQuartz–microperthite–hornblende–garnet–plagioclase granulites belonging to the Highland Series of Ceylon are described. The invariable presence of accessory graphite suggests their metasedimentary origin and their chemical composition indicates a possible derivation from feldspathic sandstones. Although the mineral assemblage of these granulites is diagnostic for the upper almandine–amphibolite facies, they are interlayered with orthopyroxene-bearing charnockites of the granulite facies. It is concluded that PHO was initially higher in the sandstones than in the surrounding rocks, and that it remained so during metamorphism under granulite facies conditions, thereby retarding the dehydration reactions that took place elsewhere in the vicinity.
New records of fertile Rhyniophytina from the late Silurian of Wales
Authors: Edwards D. , Rogerson E. C. W. 
Published: May 2009

SummaryWhitcliffian and Downtonian macroplants of rhyniophyte morphology are described from Capel Horeb Quarry, Powys, Wales. Both floras contain Hostinetla Stur, Cooksonia Lang and Steganotheca Edwards. They are briefly compared with others of similar age, and the contribution, particularly of the Whitcliffian assemblage, to our knowledge on the early colonisation of the land by vascular plants is discussed.
The significance of potassium–argon ages in the vicinity of the charnockitic Ernabella Adamellite, Australia
Authors: Wilson A. F. , Green D. C. 
Published: May 2009

SummaryPotassium–argon dates from hornblende-bearing pyroxene granulites in a large xenolith near the margin of the charnockitic Ernabella Adamellite, central Australia, are interpreted in the light of oxygen isotype studies of associated mineral phases which give a detailed thermal history of the Adamellite and associated rocks.
The trilobite genusPlacopariafrom the Ordovician of the Valongo area, North Portugal
Authors: Romano M. 
Published: May 2009

SummaryThe three species ofPlacoparia; P. (Placoparia) cambriensisHicks,P. (Coplacoparia) tournemini(Rouault) andP. (Coplacoparia) borniHammann have been recognized from the Ordovician of North Portugal. New subspecies ofP. (Placoparia) cambriensishave been established on the basis of differences in the pygidium and suggests the presence of two, broadly coeval, populations in western Europe during the Llanvirn. Quantitative analyses have provided information on growth patterns.
Ordovician echinoderms from Greenland
Authors: Paul C. R. C. 
Published: May 2009

SummaryOrdovician echinoderms from Greenland include:Glyptocystites groenlandicussp.nov. which is distinguished from otherGlyptocystitesby a very coarse slit spacing in its pectinirhombs (1 slit per 0.365 mm) and by its ambulacral structure; ?Macrocystellasp.;Cheirocystellasp and ?Carabocrinussp. A variety of unidentified stem and cup plates of crinoids is described and illustrated.
A greenstone belt—basement relationship in the Tanganyika shield
Authors: Haidutov I. S. 
Published: May 2009

SummaryAn Archaean greenstone belt, occupied by rocks of the Nyanzian System, rests apparently unconformably on a basement composed of the metamorphites of the Dodoman System in the central part of the Tanganyika shield. The latter were originally metamorphosed in granulite facies. Two episodes of migmatization were imposed on this earlier crust producing two complexes of anatectic granitoids (Puma and Ikungi) which locally have a charnockitic character. Differences in structural setting suggest that they were developed in connection with two major tectonic events. A basin-like structure was built up during the second – Ikungi – in which the Nyanzian System occurs. The Nyanzian rocks are not migmatized and their juxtaposition with the migmatites suggests that they are of younger age. Another tectonism took place after deposition of the greenstones as a result of which they were intensely deformed. Two types of intrusive granites were emplaced in the greenschists upgrading them to hornfelses during this tectonism. An interesting feature is the coincidence of the general tectonic axes of these three events. For the successively established metamorphic processes in this Archaean nucleus a gradual downgrading of metamorphic facies is characteristic, showing its irreversible development.
Preservation and abundance of palynomorphs in Svalbard
Authors: Hughes N. F. , Harland W. B. , Smith D. G. 
Published: May 2009

SummaryA summary is given of the preservation and general abundance information on palynomorphs of post-Silurian age in Svalbard. An explanation of the distribution of successful and unsuccessful palynomorph extraction is attempted, with a conclusion that varying burial history under other sediment was the principal controlling factor.
A gravity survey of Islay, Scotland
Authors: Durrance E. M. 
Published: May 2009

SummaryThe results of a gravity survey of Islay indicate that, with respect to a local Bouguer anomaly datum of 260 g.u., a positive anomaly of 100 g.u. occurs over the Lewisian gneiss of the Rhinns of Islay, and, immediately to the E, a negative anomaly of —120 g.u. occurs S of Bowmore. Both anomalies trend N—E to S—W. The negative anomaly is interpreted as due to the presence of a structural basin occupied by a maximum 4600 m of Bowmore Sandstones and Dalradian meta-sediments. The boundary between the Lewisian gneiss and this basin is the Loch Indaal fault. At the head of Loch Indaal this fault bifurcates, one branch continuing north-eastwards as the Bonahaven fault, the other trending northwards as the Loch Gruinart fault, All the faults are considered to possess transcurrent components. The stratigraphic position of the Bowmore Sandstones is similar to that of the supposed Torridonian sediments of western Islay.
Relationship between gold and manganese mineralizations in the Birimian of Ghana, West Africa
Authors: Ntiamoah-Agyakwa Y. 
Published: May 2009

SummaryStudies on the distribution of manganese-bearing rocks in the Birimian and their relationship with gold mineralization are still in progress. Both manganese and gold occur as stratabound lenses within volcano-sedimentary sequence. Evidence of pre- and post-tectonic mineralizations are present. Sedimentological evidence also suggests both may have been contemporaneous with their host rocks in an environment that was strongly Eh and pH controlled. Under present tropical conditions, other elements associated with Birimian gold mineralization, notably copper and arsenic, are highly mobile to remain in residual soils. However, manganese, like iron, remains in residual soils as oxides and could be a useful pathfinder element in the search for gold in tropical lateritic soils derived from Precambrian greenstones.
Influence of organic reefs on the evolution of post-Palaeozoic algae
Authors: Elliott G. F. 
Published: May 2009

SummaryIn reviewing those fossil algae associated with biotic reefs since the beginning of the Mesozoic, examples are discussed of algae showing evolution attributed to reef or peri-reefal conditions, those showing diversification attributed to reef environments, and those with frequent occurrence in reef conditions but with evolution not directly attributable to reefs.
The formation of fibrous texture in some veins
Authors: Finlow-Bates T. 
Published: May 2009

SummaryEvidence is presented that some fibrous veins may be formed by recrystallization of the original rock in place. It is suggested that water in a joint promotes pressure solution of the adjacent wall rock. Redeposition under conditions of tensile strain crystallization causes growth of crystal fibres into the joint and into the wall. The effects of this process are revealed by reference to fibrous veins that are present in the laminated, dolomitic, quartz sediments at Mount Isa Mine.
Early Tertiary bentonites from Svalbard
Authors: Dypvik H. , Nagy J. 
Published: May 2009

SummaryPaleontological and petrological studies of clay beds in the Basilika Formation (Tertiary age) are presented. The petrology of the beds indicates that their main constituents were derived from volcanic activity and represent bentonites. Differing composition between beds suggests several spatially separated eruptions. The volcanic source area probably lay towards the N of the present Tertiary outcrops of Svalbard. Two foraminiferal assemblages are found in the bentonites: the lower is dominated by arenaceous forms while the upper consists of calcareous species.
Intercumulus igneous layering in the Kalka Layered Intrusion, central Australia
Authors: Goode A. D. T. 
Published: May 2009

SummaryIgneous layering resulting from variations in intercumulus mineralogy has been observed in the Kalka Intrusion in central Australia. The layering is parallel to cumulus layering, and is outlined by a mottled heteradcumulus ‘clump’ texture in leucogabbros, which occur in a generally adcumulate anorthositic sequence. Such intercumulus layering is thought to originate in slow cooling intrusions at times of slow crystal accumulation and/or relatively high rates of intercumulus crystallization when a zone of melt supersaturation (the cumulus nucleation zone) rises above the intrusion floor leaving the intercumulus melt undersaturated with respect to the settled cumulus phases. Adcumulates are produced when the supersaturated zone is coincident with the top of the crystal pile. The morphological elongation of clump plates parallel to the gross layering is probably controlled by the cumulus plagioclase fabric which tends to be planar laminate.
Surface roughness measurements and the analysis of petrofabrics
Authors: Deelman J. C. 
Published: May 2009

SummaryA technique is described for direct analysis of rock-fabric, utilising hardness differences between various mineral constituents. This renders unnecessary the intermediate step of measuring optical orientations. The direct relation that exists between hardness of the components making up a particular fabric and the start of plastic deformation of each mineral can be measured quantitatively on the basis of polishing hardness differences. If the surface roughness signal is digitalised, then it is possible to automatically construct a microtopography, with contours delineating resistance of individual minerals.
A Precambrian trondhjemite boulder in Palaeozoic mudstones of NW Malaya
Authors: Stauffer P. H. , Snelling N. J. 
Published: May 2009

SummaryA boulder of plutonic igneous rock, petrologically perhaps best termed a trondhjemite, which occurs as an isolated megaclast in slumped mudstones of the Singa Formation (mainly Carboniferous) at Pulau Tepor off NW Malaya, has been dated by the potassium–argon method. Two feldspar fractions, thought to represent alkali feldspar and plagioclase (though both are highly sodic) yield ages of 1029±15 Ma and 575±10 Ma, respectively, while a whole-rock sample yields an age of 264±4 Ma. The highest age is taken to give a minimum age for the rock, and the lower ages to indicate differential argon loss. This is the first radiometrically proved Precambrian rock from the Malay Peninsula, and tends to reinforce earlier inferences of a Precambrian continent as a source area for Palaeozoic sediments in the region.
Rb-Sr and U-Pb isotopic ages of granites in the central Transantarctic Mountains
Authors: Gunner J. , Mattinson J. M. 
Published: May 2009

SummaryGranitic rocks in the central Transantarctic Mountains were emplaced and crystallized during the Early Ordovician Period, as indicated by Rb-Sr whole-rock isochron dates (488 and 463 Ma) and a concordant U-Pb date on sphene (476 Ma). Other U-Pb data provide evidence for an old inherited component of zircon in the granites.
New fusulinid evidence for the Permian age of the Palaeozoic rocks of Hydra, Greece
Authors: Stow D. A. V. 
Published: May 2009

SummaryThe Palaeozoic rocks of Hydra consist of a sequence of limestones and dolomites with some interbeds of shales and sandstones. Fusulinid foraminifera indicate the sequence is entirely Permian in age and not Carboniferous and Permian as previously thought.
Comparison of experimental and natural boudinage
Authors: Sen R. , Mukherjee A. D. 
Published: May 2009

SummaryStrain distribution inside an elliptical shaped boudin under normal compressive stress is calculated by photo-elastic methods following Frocht (1966). The strain magnitude varies horizontally within the boudin and the value increases gradually from the central part of the body to the margin. The magnitude is nearly constant along the vertical central part of the boudin. Around the margin, inside the body, it shows an average value of the vertical and horizontal stress magnitudes. No actual change in the direction of shearing stress in different parts within the boudin is noted, hence no directional change of strain. Petrofabric diagrams of different parts of natural boudins showing the quartz (0001) plots, indicate no variation in the pattern of orientation in different parts of the body. However, the elongation ratio of quartz grains shows a correspondent increase with the increment of stress magnitude as noted in the experiments.
Flora and vertebrate fauna of the Barrington Beds
Authors: Gibbard P. L. , Stuart A. J. 
Published: May 2009

SummaryPollen analyses from sediment adhering to fossil mammalian bones from Barrington, Cambridgeshire, have demonstrated that the deposit is of Ipswichian zone IIb age. This is also indicated by the mammal fauna. Herb-dominated communities, which appear to have been largely maintained by the activities of herbivorous mammals, grew locally on the river floodplain, whilst temperate mixed-oak forest was present further away.
Hexactinellid faunas in the Chalk of England and Ireland
Authors: Reid R. E. H. 
Published: May 2009

SUMMARYThe Chalk of England contains three main Hexactinellid faunas, of Lower Cenomanian, Middle and Upper Turonian, and Lower Senonian to Maestrichtian age respectively. The third is also represented in Ireland. A number of minor faunal changes can also be recognized. The three main faunas have little in common, and their relationship is not evolutionary; the changes appear to be due to migrations. By analogy with modern forms, this is likely to reflect changes in the pattern of current circulation in the Upper Cretaceous ocean.
Sedimentology of the Ghazij Formation, Harnai, Baluchistan
Authors: Kazi A. 
Published: May 2009

SUMMARYA petrographic study of the sediments of Ghazij Formation, supplemented by field observations, has been made with a view to studying the environment of sedimentation in the Ghazij Basin. It is concluded that the sediments were formed in marine and fluviatile environments. The principal source area lay to the north-west of Harnai and a palaeogeographic reconstruction of Ghazij times is attempted.
Alignment of dolines north-west of Lake Constance, Germany
Authors: Matschinski M. 
Published: May 2009

SUMMARYAn account is given of the karst features of a given area, and ways of finding some order in their apparently chaotic arrangement. The simplest characteristic to study is the alignments of the karst features. These can be determined either subjectively (following the simple overall impression given by the area), or objectively (on the basis of various mathematical or graphical operations).A distinction between “local” and “general” alignment by an elementary statistical-graphical method is proposed. This method is applied to the Lake Constance area, and the results are interpretated in relation to the geological features of the area. It is concluded that (a) the structural features of an area have a strong influence on the karst phenomena, and (b) there is a possibility of revealing, and even making geometrical determinations of, some geologically fundamental directions, e.g. tectonic—from an analysis of the distribution of such relatively superficial phenomena as karst features.
An analysis of cross-stratification of Gargaresh Calcarenite (Tripoli, Libya) and Pleistocene palaeowinds
Authors: Hoque Mominul 
Published: May 2009

SummaryThe Pleistocene Gargaresh Calcarenite is a series of fossil dunes parallel to the Mediterranean coast of Tripoli; it is composed of medium-grained skeletal carbonate sand with abundant cross-stratification. Analyses of 321 azimuthal readings show that the distribution is bimodal with modes in the NE and the SE sectors. The distribution of modes indicates that the morphology and the orientation of eolian dunes were largely controlled by the then prevailing winds, and that the overall palaeowind pattern, although generally similar to the present-day system, might have undergone periodic changes due to Pleistocene climatic ups and downs.
Wenlock plant spores and tetrads from County Mayo, Ireland
Authors: Smith David G. 
Published: May 2009

SummaryA rock sample from the Lettergesh Formation, most probably from the centrifugus Zone of the early Wenlock on graptolite evidence, has yielded microfossils including spores, most of which occur in tetrads. The spores are described and illustrated and are compared with Ambitisporites avitus Hoffmeister.
Caradoc turbidites at Poppit Sands (Pembrokeshire), Wales
Authors: James D. M. D. 
Published: May 2009

SummaryThe sedimentology of a key locality in the Caradoc of SW Wales is discussed for the first time. Five facies are described and interpreted: mudstones and siltstones (A), turbidite arenites (B), rudites (C), a diamictite of massflow origin (D), and muddy arenites rich in shaleclasts (E) which show a transition from massflow deposits to immature turbidites. Closely adjacent sections illustrate considerable lateral variations within an assemblage suggested to be of proximal turbidite character and to represent deposits high on a Middle Fan environment.
The Silurian and Lower Devonian graptolite-bearing strata in the USSR (a review)
Authors: Koren' Tatjana N. 
Published: May 2009

SummaryThe Silurian and Lower Devonian graptolite-bearing strata are widely distributed in both the platform and geosynclinal areas in the USSR. They are represented by black clay and siliceous shales, marlstones and argillites. In the main area of their distribution the regional zonal standard is established based on graptolites. They serve as the most detailed stratigraphical base for geological mapping and exploration and are used in the regional and inter-regional correlations. Correlation with other countries and continents is carried out by comparison of regional zonal successions with the unified standard of graptolite zones. The latter is compiled from the regional zonal subdivisions of the British, Czechoslovakian and Polish type sections. The zonal stratigraphy based on graptolites allows the establishment of the limits of the Silurian System and Stages/Series in the USSR. The Silurian and Lower Devonian sediments in the USSR are characterized by various geographically widespread graptolite assemblages. The most complete zonal subdivision is worked out for the Lower Silurian. The Upper Silurian and Lower Devonian zonal stratigraphy requires elaboration and precision in the future. The importance of graptolites in solving general geological problems particularly for establishing detailed stratigraphy of regions of industrial explorations considered.
A palaeomagnetic argument concerning post-Devonian displacement along the Great Glen Fault
Authors: Turner P. , Tarling D. H. , Archer R , Donovan R. N. 
Published: May 2009

SummaryThe validity of using Devonian palaeomagnetic data to determine a post-Devonian displacement along the Great Glen Fault is assessed and it is concluded that there is no statistically significant difference between previous magnetic vectors E and W of the fault and thus no palaeomagnetic evidence for a large sinistral displacement in post-Devonian times. New palaeomagnetic results are presented which suggest that the Devonian red sandstones in the Orcadian Basin have such a complex diagenetic and palaeomagnetic history that they will then be unsuitable for such tectonic evaluations in the foreseeable future, although palaeomagnetic dating can be used to resolve some diagenetic-sedimentary features.
Cleavage formation in the Skiddaw Slates of the Northern Lake District, England
Authors: Roberts D. E. 
Published: May 2009

SummaryCleavage structures from two localities in the Northern Lake District, England, are described, and they are discussed critically in relation to the tectonic de-watering hypothesis. It is concluded that, whilst tectonic de-watering may aid in the formation of a slaty cleavage, strain is the primary mechanism for producing such structures.
Non-metals in soils of the Teign Valley of SW Devon as indicators of mineral veins
Authors: Merefield J. R. 
Published: May 2009

SummaryQuantitative methods of X-ray fluorescence analysis have been employed to the determination of Pb, Zn, Ni, As, Rb, Ce and Y, in soils of the Teign Valley of SW Devon. The results enable a comparison to be made of the ore metal and non-metal anomalies found, and demonstrate the applicability of non-metals as lode indicators.
Potassium–argon ages from the Tertiary Ring Complexes of the Ardnamurchan Peninsula, Western Scotland
Authors: Mitchell J. G. , Keen K. P. 
Published: May 2009

SummaryPotassium–argon age studies on the central intrusion complexes of Ardnamurchan, Western Scotland, indicate that they were emplaced at a time between 59 and 61 Ma ago. The time period associated with the cooling was probably less than of the order of a million years. The temporal setting of the Ardnamurchan complexes in the context of the other British Tertiary igneous centres is examined in the light of the new data.