bluuebunny/crossref_metadata_2025_split huggingface dataset:
Sub-marine volcanic explosion during the sedimentation of the Baghdhar Limestone of Dalhousie Chamba, Himalaya
Authors: Saxena M. N. , Singh S. K. 
Published: May 2009

SUMMARYVolcanic lapelli, bomb-like fragments and dust, along with other ejectamenta were incorporated in the limestone during its sedimentation. The limestone belongs to the Chail Series of Algonkian age. The volcanic explosion took place under sub-marine conditions.
A Note on Possible Differentiation Trends in Tertiary to Recent Lavas of Kenya
Authors: Wright J. B. 
Published: May 2009

AbstractThe distribution of Tertiary to Recent lavas in part of south-west Kenya is outlined, and attention drawn to the predominance of nepheline-rich Miocene lavas over other types west of the Rift Valley, which contrasts with the Pliocene olivine basalt-trachytecomendite association predominating within the Rift Valley. It is inferred that widespread Miocene phonolites west of the Rift Valley derived from a parent of approximate mela-nephelinitic composition, while within the Rift Valley extensive Pleistocene trachytes differentiated from an olivine basaltic parent. Plots of normative feldspathoid: feldspar versus silica, for analysed lavas from Kenya and Tanganyika, are used to illustrate the trends envisaged. The frequent association of nephelinitic lavas and carbonatite complexes in Kenya is discussed and the possibility mooted that the presence of nephelinite lavas may be indicative of nearby carbonatite complexes.
Significance of the punctation mosaic of the Jurassic thecidellinid brachiopod Moorellina
Authors: Baker P. G. 
Published: May 2009

SummaryStudy of the punctation mosaics of Moorellina granulosa (Moore) and Moorellina ornata (Davidson), revealed by serial sectioning and stereoscan photomicrographs, shows that the apparent random distribution of punctae may be reconciled to two superimposed regular insertion patterns. Careful plotting of the endopunctae of M. granulosa from serial, cellulose acetate peels, reveals the presence of impersistent punctae. A new model is proposed, based on superimposed insertion patterns and offering an explanation for impersistence of punctae.
Craton-Mobile Belt relations with particular reference to the Mosetse-Matsitama area, north-eastern Botswana
Authors: Bennett John D. 
Published: May 2009

SummaryThe Pre-Cambrian rocks of north-eastern Botswana comprise two major geotectonic domains: the south-western extremity of the Rhodesian craton, and the surrounding mobile belts– namely the Limpopo Mobile Belt to the south and the Shashi Mobile Belt to the west-southwest. The Mosetse-Matsitama area bears affinity to both these environments and this contribution attempts to assess the relationships of the area within the context of the regional geological framework. The area is underlain by a supracrustal schist belt which is interfolded with an infracrustal basement of gneisses and granitic rocks. The schist belt includes metasedimentary and probably metavolcanic rocks of low metamorphic grade and, therefore, contrasts sharply with the rocks of higher metamorphic grade which comprise the basement. Only in the south-west of the belt does a transitional relationship between the two major units occur. Geographical and geological criteria characteristic of both the major geotectonic environments are described, and it is concluded that the area shows a transition from a cratonic to a mobile belt environment. Involvement in a developing mobile belt would initially affect the infracrustal basement, allowing the supracrustal rocks to retain their cratonic characteristics to a more advanced stage.
Lava Channels on Tristan da Cunha
Authors: Baker P. E. , Harris P. G. 
Published: May 2009

AbstractLava channels flanked by lava levees are described from Tristan da Cunha. These have been formed by the building up of the levees by overflow and solidification of fluid lava from the channels. A distinction is made between the terms “lava levee” and “lava moraine”.
Composite phonolite tholoids in the Cenozoic volcanic province of Nigeria
Authors: Wright J. B. , McCurry Patricia 
Published: May 2009

SummarySmall trachyte and phonolite bodies are shown as eroded plugs on published geological maps of part of north-eastern Nigeria. Field relationships at two such ‘plugs’ strongly suggest them to be extrusive in origin, formed of an earlier tholoid-building phase, followed by extrusion of a spine (plug dome) of very viscous lava, now forming the central peak at each locality. Petrographic data show that the tholoid and spine-forming lavas are phonolites of contrasted composition. Eruption of salic lavas from scattered centres appears to have occurred intermittently between mid-Tertiary and Pleistocene times.
Surface textures of sand-grains from the Hertfordshire Pebble Gravels
Authors: Hey R. W. , Krinsley D. H. , Hyde P. J. W. 
Published: May 2009

SummaryThe Pebble Gravels of Hertfordshire are among the earliest Pleistocene deposits of the London Basin. They comprise at least three successive units, and according to the most recent published views the oldest of these is marine, the youngest fluviatile, the intermediate partly marine and partly fluviatile. In the absence of fossils these views have remained open to question. Electron microscope studies of the surface textures of sand-grains suggest, however, that they may well be substantially correct.
A primary igneous texture from the Lizard Peridotite, Cornwall
Authors: Rothstein A. T. V. 
Published: May 2009

SummaryDetailed studies by Flett and Green have shown the Lizard complex to be a deformed body of considerable complexity. One of the principal results of the deformation has been the recrystallization of the primary peridotite. New evidence is presented concerning the original features of this high temperature peridotite. It is concluded that in some of the primary rocks there is preserved the structure and texture of the crystallization of an interstitial pore liquid trapped within a primary framework of olivine crystals.
Myrmekite from the Charnockitic Rocks of the Eastern Ghats, India
Authors: Bhattacharyya C. 
Published: May 2009

SummaryThe myrmekite occurring in acid to basic charnockites of the area around Garbham and Shikaruganji, Srikakulam district, Andhra Pradesh is described. Myrmekite, whenever present, occurs only at the contact of plagioclase and potash feldspar. The textures and paragenesis of minerals suggest that potash feldspar reacted with plagioclase giving rise to myrmekite under favourable stress condition, higher stress favouring the formation of myrmekite. The difference in the stress factor or the microstrain pattern in the rock can explain the presence of myrmekite at some contacts of plagioclase–potash feldspar and absence in others.
Mineralogy and Textures of some cordierite–sillimanite rocks from Labrador, Canada
Authors: Singh S. K. , Kamineni D. C. 
Published: May 2009

SummaryThe cordierite–sillimanite rocks first reported from Joan Lake Area, Labrador, show some unusual mineral associations and textures. Two myremkitic intergrowths, one among cordierite, potash feldspar and quartz, and the other between potash feldspar and plagioclase feldspar, are observed. The presence of microcline–microperthite and the textures described in the sequel indicate that these rocks were recrystallized at high temperature.
Authigenic Minerals in Carboniferous Sediments from Central Vestspitsbergen
Authors: Hutchins Philip F. 
Published: May 2009

AbstractPostdepositional low-temperature mineralogical changes in Carboniferous sedimentary rocks from Vestspitsbergen are described. These include the crystallization of apatite, quartz, and feldspar, and the replacement of feldspar and quartz by calcite and dolomite. Minerals of the chalcedonite–lutecime–quartzine group also occur.
Skipsey's Marine Band and Red Coal Measures in Fife
Authors: Francis E. H. , Ewing C. J. C. 
Published: May 2009

AbstractMine sections beneath the Firth of Forth at Wellesley Colliery fill gaps in the Knowledge of the strata adjacent to the junction between Middle and Upper Coal Measures. A hitherto unrecorded marine band which may formerly have been confused with Skipsey's Marine Band is now placed about 70 feet lower in the succession. A coal seam near the base of the Upper Coal Measures contains a rib of kaolin mudstone comparable with tonstein. Local reddening and alteration of coal to limestone in the Upper Coal Measures and more particularly in the upper part of the Middle Coal Measures is typical of a zone of partial oxidation beneath some major unconformity which may lie within the Upper Coal Measures or at some unlocated sub-Permian horizon above. Structureless highly-coloured clayrocks in the Upper Coal Measures, however, are regarded as primary red beds comparable with, and perhaps the equivalents of, the Etruria Marl of the English Midlands.
The Pleistocene Drift Succession at Porth-Clais, Pembrokeshire
Authors: John Brian S. 
Published: May 2009

SummaryThe paper represents a reassessment of the drift stratigraphy at Porth-clais. The characteristics of the various Pleistocene deposits at the site are analysed in detail, and the sequence of drifts is then examined in its regional context. While the age of the raised beach at Porth-clais is still open to doubt, it seems that the non-calcareous till was deposited during a Late Weichselian glaciation by the Irish Sea glacier. This glacier probably extended much further south in St. George's Channel than suggested by other workers, although the ice stream which crossed St. David's Peninsula may not have been very thick.
Xenodiscacean Ammonoids and their bearing on the discrimination of the Permo-Triassic boundary
Authors: Tozer E. T. 
Published: May 2009

SUMMARYXenodiscacean ammonoids from Dzhulfa in Soviet Transcaucasia, assigned to Tompophiceras, Bernhardites and Paratirolites, have been interpreted as indicating that the enclosing beds, which also contain tetracorals, productacean brachiopods and goniatites, are Lower Triassic. Critical examination of the identifications shows that these beds should be regarded as Permian, not Triassic. Tompophiceras and Bernhardites are based on Triassic type species but the specimens from Dzhulfa are not demonstrably congeneric. Interpretation of Tompophiceras as a genus with a fastigate venter is rejected. Paratirolites, previously regarded as Triassic, is evidently Permian, and is now recorded from Madagascar, this being the first record outside Transcaucasus. New evidence is presented concerning the exact age of Glyptophiceras. The Dzhulfa section has been interpreted as providing a continuous transition, in the marine facies, between beds of Permian and Triassic age. This interpretation is rejected. It remains probable that there are no sections, in any part of the world, that do so.
The repeated development of identical joint patterns, north-east Tasmania
Authors: Williams Emyr 
Published: May 2009

SUMMARYExamination of a contact between Late Devonian intrusive acid igneous rocks and Siluro-Devonian Mathinna hornfels. and the unconformity between these rocks and the overlying Permian beds, has revealed the relative ages of the joints developed. The steep joints of the acid igneous rocks are demonstrably of pre-Permian age although they form a pattern identical to those of the Permian beds, and each joint set is correlated with approximately parallel trending sinuous normal faults. The repeated development of the steep joints is attributed to reactivation of a fundamental mechanism. Some of the joints in the igneous rocks occur between compositional layers which have inherited their shape from the form of the joint-governed contact with the hornfels.
Evidence from Recent Plankton Regarding the Biological Affinities of Tasmanites Newton 1875 and Leiosphaeridia Eisenack 1958
Authors: Wall D. 
Published: May 2009

AbstractFollowing a bricf survey of previous literature concerning microfossils of the genera Tasmanites Newton 1875 and Leiosphaeridia Eisenack 1958 (generally known as leiospheres), two present day green algae are described (Pachysphaera pelagica Ostenfeld 1899 and Halosphaera minor Ostenfeld 1899). These organisms are compared with members of the fossil genera reviewed above and on the basis of this comparison it is concluded that the biological affinities of Tasmanites and some species of Leiosphaeridia lie with the Chlorophyceae. A possible mode of life is suggested for the fossils and the systematic position of the genera Tasmanites and Leiosphaeridia is reviewed but not altered.
Geochemical comparison of the Stillwater complex and alpine-type ultrabasic complexes, Beartooth Mountains, Montana and Wyoming
Authors: Bowes D. R. , Skinner W. R. 
Published: May 2009

SUMMARYThe field of composition and the geochemical trend of the lower portion of the stratiform Stillwater igneous complex correlate well with the field and trend for alpine-type ultrabasic masses in the nearby gneissic basement of the Beartooth Mountains. This is consistent with a derivation of some alpine-type masses by the tectonic disruption and metamorphism of stratiform complexes.
Faunal Realms in Jurassic and Cretaceous Belemnites
Authors: Stevens G. R. 
Published: May 2009

AbstractBoreal, Tethyan, and Indo-Pacific faunal realms may be recognized in belemnite faunas of Callovian and most of later Mesozoic time. The presence of such clearly-defined realms indicates restriction of belemnite migration and perhaps the belemnites were confined to the shelves, extensive areas of deep water forming barriers. Migration of belemnites in the Tethyan and Indo-Pacific realms may be explained in terms of deep water barriers, but delimitation of the Boreal realm is thought to be a result of climatic zoning.
Some Unusual Ripple Marks in Carboniferous Limestone near Spittal, North Northumberland
Authors: Shiells K. A. G. 
Published: May 2009

AbstractRipple marks of unusual dimensions are recorded from the Sandbanks Limestone (Middle Limestone Group) at a foreshore locality 3 miles south of Spittal in North Northumberland. The structures are thought to have been formed in a partially cohesive calcareous mudas wave-oscillation ripples which have undergone penecontemporaneous modification.
Pseudomigmatites in the Abitau Lake Area, District of Mackenzie, Northwest Territories, Canada
Authors: Harry W. T. 
Published: May 2009

AbstractThe Abitau Lake area, N.W.T., chiefly consists of medium-to-coarse-grained quartzo-feldspathic gneisses. Many of these are granoblastic, presenting little or no microscopic evidence of deformation. Others are highly tectonized and foliated varieties that sometimes form pseudomigmatites easily mistaken in the field for true migmatites formed by lit-par-lit injection of pink granite into more basic grey gneiss. The last, however, are found after detailed examination to be granitic rocks that owe their misleading appearance and distinctive fabric to deformation during isochemical amphibolite fades metamorphism. Surprisingly they are not mylonites. Their fabric, like that of the other foliated gneisses is dominated by the parallelism of dark minerals and elongated quartz crystals. It resembles that of typical European granulites and often seems largely due to compression acting in a direction normal to the foliation plane with little or no transport in that plane. Tectoniza-tion did not promote the formation of myrmekite or microperthite but may have assisted to some extent the production of epidote from hornblende in certain specimens.
Layered ultrabasic lavas from Cyprus
Authors: Searle D. L. , Vokes F. M. 
Published: May 2009

SUMMARYUltrabasic lavas of variable picritic-peridotitic composition are found widely distributed in the Upper Pillow Lava member of the Troodos Volcanic Series in Cyprus. Recent work reveals layering of olivine crystals in both lava flows and pillows. An account is given of the field relations of the layered units, their petrography, mineralogy and chemistry.
Disturbed Keuper Marl beneath the river gravels of the Soar basin
Authors: Bridger J. F. D. , Rice R. J. 
Published: May 2009

SUMMARYA recent excavation at Newtown Unthank, 9 km west of Leicester, has permitted study of the sub-alluvial gravels of the Rothley Brook valley. The junction of the gravels with the underlying Keuper Marl is sharply contorted, with an upward progression from undisturbed bedrock, through displaced marl and siltstone layers into masses of marl which have apparently been thrust up into the overlying gravel and incorporate many foreign stones. Possible causes of the structures are outlined, and reasons adduced for believing them to be of periglacial origin and of Weichselian age. Comparable occurrences have been recorded from elsewhere in the Soar basin, and also from other parts of the Midlands, and these are briefly discussed.
Minor Acid Intrusions and Dykes of Lamlash—Whiting Bay Region, Arran
Authors: Srirama Rao M. 
Published: May 2009

AbstractThin sills and dykes of pitchstone and felsite and dykes of crinanite, olivine-dolerite, tholeiites of different types, quartz-dolerite, andesite, craignurite-pitchstone, felsite and porphyry are described and the importance of contact and deep-seated hybridization of two magmas of contrasting basic and acid composition in their formation established. Among the dykes, the sequence of intrusion is surmised to be as follows: basic, sub-basic, intermediate, acidic, and, again, basic.
Early Slope Development in an Expanding Stream System
Authors: Carter Carol S. , Chorley Richard J. 
Published: May 2009

AbstractA study of the morphometry of an ephemeral stream system which is incising itself into a terrace of the Farmington River, Connecticut, supports the regional relationship between stream-channel gradient and valley-side slope angle suggested by Strahler (1950). The continuing areal extension of the system allows stream order to be employed here as a relative measure of the passage of time. Thus it is possible to recognize that steepening and parallel development of a given valley-side slope may have their place in a sequence of early stage erosional development characterized by headward channel extension and ramification.
Some Namurian Conodonts from North Staffordshire
Authors: Higgins A. C. 
Published: May 2009

AbstractThe paper describes a conodont fauna from the Namurian of North Staffordshire. Seventeen genera and thirty-four species are identified in the fauna, of which Hibbardella fragilis, Hibbardella pennata, Lambdagnathus macrodentata, Mestognathus bipluti, Neoprioniodus spathatus, and Subbryantodus subaequalis are new species. The composition of the fauna and its correlation with similar faunas in the United States of America and Germany are discussed.
Lepidostrobophyllum fimbriatum (Kidston 1883) from the Drybrook Sandstone (Lower Carboniferous)
Authors: Allen K. C. 
Published: May 2009

AbstractLepidostrobus fimbriatus Kidston is redescribed as Lepidostrobophyllum fimbriatum (Kidston) from a new locality, in the Drybrook Sandstone of the Forest of Dean. The sporophyll consists of two parts bent at right angles, forming a heel of hard tissue. The sporangium is attached to a small area by the midrib, and is only partly occupied by the four spiney megaspores. A ligule is present.
On the Basis of Pleistocene Correlation in East Africa
Authors: Flint Richard Foster 
Published: May 2009

AbstractThe scheme currently used in East Africa for Pleistocene stratigraphic correlation is bases on climate. This basis is thought to be undesirable because it consists of second-order concepts rather than of primary, objective units and because its unconventional character inhibits correlation between East Africa and other regions. Furthermore the conceptual sequence of pluvial and interpluvial Pleistocene climates is not fully supported by the field evidence described thus far. Local support exists for the Gamblian and post-Gamblian and post-Gamblian wet climates, and at one locality a wet phase of pre-Gamblian age is admissible. The other units of the current scheme require factual support before they can be accepted. It is suggested that a more conventional basis of Pleistocene correlation in East Africa is desirable.
On Garnet Coronites from Koraput, Orissa
Authors: Bose Mihir K. 
Published: May 2009

AbstractDevelopment of garnet coronas in a small meta-mafite body, forming a tilted dome within the parametamorphics, is reported and the petrography of the coronites is described. Garent coronation marks a stage in the metamorphic and textural evolution of the rocks. The origin of coronas and related features is discussed.
On the Nature of the Coralline Crag
Authors: Baden-Powell D. F. W. 
Published: May 2009

AbstractA new fossiliferous section in the Coralline Crag of Suffolk is described, and its fauna is analysed as a clue to the conditions under which these beds were formed; in particular, the theory that the temperature of the Crag sea was affected by the alternate breaching and closing of land-bridges to the north and south of the North Sea area is considered unnecessary to account for the facts as seen in the field. Further, the Coralline Crag is correlated with the Astian formation of the Mediterranean, and reasons are brought forward to show that the supposed “Boytonian” Zone of the Coralline Crag does in fact not exist.
Petrography of the Mesozoic Succession of South Wales
Authors: Crampton C. B. 
Published: May 2009

AbstractThe heavy mineral suites of the Trias, Rhaetic and lowermost zones of the Lower Lias in the Vale of Glamorgan of South Wales are described. The northerly coastline of the Mesozoic sea, roughly coincident with the present-day periphery of the Coalfield, consisted mainly of Carboniferous Limestone and in places, the Old Red Sandstone and Millstone Grit. The mineral assemblage at any particular point in the littoral zone was determined largely by the nature of the outcropping rocks of the coastal mainland, the derivation of detritus being very localized. Within this zone some degree of gravity sorting of the detritals occurred, this implying a relatively steeply inclined coastal sea-bed. An off-shore current carried detritus from the Armorican land-mass of Britanny and granite of South-West England to this area where the detritals were dispersed thinly throughout the locally derived sediment.
Ignimbrite in the Kilchrist Vent, Skye
Authors: Ray P. S. 
Published: May 2009

AbstractIgnimbrite steeply intrusive into the basaltic agglomerate of the Kilchrist vent is described. Like the intrusive ignimbrite near Kilchoan, Ardnarnurchan, it shows flow structure parallel to the walls, flow being similarly expressed by the elongation and alignment of the constituent shreds of devitrified glass and pumice lapilli. Fragments of basalt, derived from the vent agglomerate, are sometimes also drawn out in the direction of flow.
The Form of the Beinn An Dubhaich Granite, Skye
Authors: King Basil C. 
Published: May 2009

AbstractThe form of the Beinn an Dubhaich granite was considered by Harker to be boss-like. Here evidence is put forward to suggest that it may have the form of a sheet emplaced along the Torridonian-Cambrian thrust plane. The alternative hypothesis has the merit of avoiding the serious difficulties appreciated by Harker regarding the mode of emplacement of the granite.
The Strength and Stress-Strain Characteristics of Oakdale Coal under Triaxial Compression
Authors: Hobbs D. W. 
Published: May 2009

AbstractLaboratory measurements of the effect of a confining pressure on the strength and stress-strain characteristics of a metallurgical coking coal are described. Several-fold increases in the strength, the Young's modulus and the elastic strain at failure were found as the confining pressure was increased to 5,000 lb./n.2. The results are discussed in relation to various criteria of failure. It was found that failure was represented by Coulomb's equation relating shear stress and normal stress, provided the observed angles of fracture were not influenced by local edge stress concentrations.