bluuebunny/crossref_metadata_2025_split huggingface dataset:
Scour casts with inclined terraces
Authors: Whitaker J. H. McD. 
Published: May 2009

SummaryA specimen from the Krosno Beds (Oligocene) of the Polish Carpathians shows irregular scour casts, in the shallower parts of which terracing is horizontal but in the deeper parts of which it is dipping at up to 27°. It is inferred the the original sea floor consisted of cross-laminated surface layers. The palaeocurrent significance of inclined terraces is discussed.
Carbonate deposition on the river floodplains of the Wood Bay Formation (Devonian) of Spitsbergen
Authors: Friend P. F. , Moody-Stuart M. 
Published: May 2009

SummaryThe argillaceous siltstones of the floodplains contain, on average, 15% of calcium carbonate. This appears to have been precipitated between the detrital grains shortly after their deposition. The siltstones also contain calcium carbonate concretions which formed as the ground water dried out in the upper part of the water table. Bedded marlstones, containing up to 68% of carbonate in the lakes appears to have been stimulated by Charophyte algae. The marlstones include dolomite in some parts of the Formation. The channel-fill deposits include carbonate detritus from the source areas, and from reworking of Wood Bay Formation sediments. They are frequently cemented by calcite.The regional pattern of carbonate derivation, transportation and deposition is summarized.
A note on deformed igneous sheets in the Durness Limestone of the Strath district of Skye
Authors: Nicholson Robin 
Published: May 2009

SummaryClearly boudined and folded igneous sheets occur in Durness Limestone on the south side of the Tertiary Ben an Dubhaich granite. Obvious Tertiary dykes in nearby Mesozoic rocks are not deformed at all, nor has such deformation been described previously from the Caledonian activity in the Cambro-Ordovician of the north-west Highlands. Its appearance here does fit Clough's description (in Peach et al. 1907) of an unusually strong Caledonian penetrative deformation in the Strath Limestone, while the fact that all but one of the sheets are dolerites, a rock not elsewhere known from the Cambro-Ordovician but typical rather of the Tertiary activity for which Skye is famous, and that the other is a two feldspar porphyry very like the Ben an Dubhaich granite, point to the possibility of Tertiary deformation.
The Glacial Till of Fair Isle, Shetland
Authors: Flinn Derek 
Published: May 2009

SummaryReddish-brown glacial till containing millet seed sand grains occurs on Fair Isle, Shetland. Both the colour and the millet seed grains may have come from Permo-Triassic sandstones on the sea floor in the neighbourhood of Fair Isle, since the Devonian rocks of the area are not often red and do not give rise to till containing millet seed grains.
Echinoid preservation in the Upper Estuarine Limestone of Blisworth, Northamptonshire
Authors: Aslin C. J. 
Published: May 2009

SUMMARYThe study of echinoids and their associated limestones in the Upper Estuarine Series of Blisworth has shown that the echinoid tests have been preserved in two ways. (1) Without spines, jaw apparatus or apical disc. When whole, such tests are usually full of sediment. Echinoids of this type are usually associated with clean well-sorted fragmental limestones. (2) Bearing spines and with apical disc and jaw apparatus in place. When whole, the tests are usually full of clear crystalline calcite. Echinoids of this type are usually associated with poorly sorted, complex, muddy limestones with a high proportion of terrigenous material. The sedimentary environment and the relative rate at which the echinoid material passed through the depositional interface appears to have controlled both the limestone lithology and the condition of the echinoid material.
Paragenesis of a Cordierite-Garnet Granulile from Assam, India
Authors: Sastri G. G. K. 
Published: May 2009

AbstractA cordierite-garnet granulite from Assam, India, carries optically positive cordierite, garnet, spinel, biotite, and sillimanite. The optics of the cordierite are: α = 1·534, β = 1·540, γ = 1·548, 2V = + 81°, while the composition of the garnet inferred from the writer's charts, in terms of the end-members, is Al73Py20Sp2An3Gr2. The development of an iron-rich garnet in association with a magnesium-rich cordierite is discussed, and data are presented to show that such garnets have a restricted compositional range. It is doubtful if the FeO/MgO ratio in a cordierite-garnet assemblage can be used for interpretation of the physical conditions governing the formation of the host rock.
Quartz Fabric Reorientation in the Region of Benmore Assynt, North-West Highlands of Scotland
Authors: Crampton C. B. 
Published: May 2009

AbstractIn the Assynt area of the North-West Highlands of Scotland a regional preferred orientation of quartz [0001]-axes of sedimentary origin in Cambrian quartzites has withstood considerable deformation and destroyed only with the onset of granulation in the immediate vicinity of thrust planes. After partial granulation the remaining scattered quartz grains develop a preferred orientation of [0001]-axes quite distinct from the sedimentary fabric. Recrystallization is apparent well away from the thrust planes, but only supersedes granulation along certain sections of the major Moine Thrust plane. The preferred orientation of quartz [0001]-axes in these recrystallized fabrics is somewhat variable. The regional quartz fabric of metamorphic origin in Moine rocks immediately above the thrust planes can experience a similar deformation, recrystallization following granulation with the development of quartz fabrics similar to those in recrystallized quartzites below the Moine Thrust plane.
The Wenlock sediments of north-west Galway, Ireland.
Authors: Laird M. G. , McKerrow W. S. 
Published: May 2009

SummaryThis work describes the Wenlock sedimentary sequences south of Killary Harbour where the fullest successions in north-west Galway are exposed; much of the Upper Silurian in the east (Joyces Country) has been removed by erosion.The Wenlock beds (the Upper Owenduff and Killary Harbour Groups) rest on shallow marine and continental sediments (the Lower Owenduff Group) of Upper Llandovery (C5–6) age. Conglomerates near the base of the Wenlock are followed by 1,500 m of sandstones, which are mostly turbidites and which contain Middle Wenlock graptolites. These basin deposits are succeeded by a transitional sequence of rise, slope and shelf clastics, also of Middle Wenlock age. The youngest Silurian beds exposed are 800 m of red lagoonal deposits withLingula.During Wenlock times, the sediment supply to north-west Galway was mainly from the north and north-west. This observation fits well with the regional picture which places Galway near the north-west margin of a Silurian basin which extended eastwards across Ireland.
Appinite xenoliths and associated rocks from the Ben Nevis igneous complex
Authors: Haslam H. W. 
Published: May 2009

SummaryAn area is described in which the main rock type is a variable dioritic rock, thought to have been formed by the expulsion of the residual acidic liquid from a largely crystalline quartz-diorite magma. It contains xenoliths of pyroxenite and appinite. The latter consist largely of hornblende, with some diopside, quartz, orthoclase microperthite and oligoclase. They are considered to be the reaction products of the outer margin of a magma and the adjacent calcareous country rock.
Rubidium and Strontium age determination of some Pre-Cambrian granitic rocks, S.E. Uganda
Authors: Old R. A. , Rex D. C. 
Published: May 2009

SummaryWhole rock rubidium-strontium age determinations on granitic bodies in S.E. Uganda give ages of 2930 m.y. for the Masaba Granite and 2430 m.y. for the Buteba Granite and granitic gneisses. The former age is considered to represent the upper age limit of the post-Nyanzian orogeny, and 2430 m.y. the upper age limit of the post-Kavirondian orogeny. A second isochron age of 2100 m.y. for the Masaba Granite may reflect a second intrusion, or remobilization of part of the original granite associated with the Buganda–Toro orogeny. Tentative correlations are suggested between these age groups and others within the Tanzanian Shield and beyond.
Diopside-Orthoclase-Hornblende Rocks from the Lewisian Paragneisses of South Harris, Outer Hebrides
Authors: Dearnley R. 
Published: May 2009

AbstractAn account is given of the petrography and chemistry of a diopside-orthoclase-hornblende rock within the quartzose garnetkyanite-biotite granulites of the Leverburgh Lewisian paragneiss belt of South Harris.
The Structure of the Scotia Arc
Authors: Hawkes Donald D. 
Published: May 2009

AbstractIt is suggested that the Scotia Arc was formed after the disruption of a continental strip between South America and Antarctica by an eastward advance of the Pacific crust; volcanic island arcs and associated trenches developed at the juction of the Pacific and Atlantic crustal types; the Scotia Arc migrated eastward with time; and that the crustal structure of the Scotia Sea is in the process of changing from an oceanic (Pacific) to a continental type.
Some Glacial Deposits and their Relation to the Hippopotamus-bearing Beds at Barrington, cambridgeshire
Authors: Norris G. 
Published: May 2009

AbstractTill fabrics on the ridge above Barrington show a variety of preferred orientations and their origins are discussed. Not all the fabrics can be attributed to ice transport. Lowestoft and Gipping Tills are differentiated on their lithologies, fabrics, and erratics, and the contained heavy minerals and microfossils are also considered. Correlation of the associated solifluxion deposits with the sequence in Barrington Village has shown that the Hippopotamus-bearing Barrington Beds are not younger than the Hoxnian Interglacial (Elster/Saale) and may be considerable order.
Kentallenite-Lamprophyre-Granite Age Relations at Kentallen, Argyll
Authors: Bowes D. R. 
Published: May 2009

AbstractAn intrusive sequence of kentallenite-lamprophyre-granite is clearly indicated by cross-cutting relations at Kentallen. This sequence is the same as that recorded elsewhere in Argyll. It is suggested that the time gap between the intrusion of the kentallenite and of the lamprophyre is small compared with that between the intrusion of the lamprophyre and of the granite.
Element Distribution in Two Epidiorite Sills from the Central Grampian Highlands of Scotland
Authors: Ball T. K. 
Published: May 2009

AbstractMagmatic differentiation is demonstrated in two epidiorite sills from the Grampian Highlands of Scotland, and the distribution of major and minor elements compared with data given for other intrusions, and for trace elements in the Whin Sill at High Cup Gill, Westmorland. The latter sill has Sr and Ba enriched towards the top. The element distribution for the epidiorite sills indicates that they are overturned. The data are conclusive for one sill but merely suggestive for the other, since such phenomena as multiple injection may also have affected the element distribution. The structural significance is briefly discussed.
The Phuket Group, Peninsular Thailand: a Palaeozoic ?geosynclinal deposit
Authors: Mitchell A. H. G. , Young B. , Jantaranipa W. 
Published: May 2009

SummaryThe Phuket Group is the oldest rock unit in the Phuket-Takua Pa-Krabi region of the Thai Peninsula. The Group comprises two Formations: a Lower Formation of Ordovician, or possibly Cambrian, to Lower Permian age, exceeding 3 km in thickness, and an Upper Formation of early Permian age between 100 and 200m thick.Facies analysis shows that the Lower Formation consists of mass flow deposits and sandstones comparable to the deposits of modern continental rises and continental slopes. The Upper Formation was deposited in a shallow marine and probably deltaic environment. The Phuket Group and litho-logically similar sedimentary rocks to the north and south occupy an elongate belt extending from the Shan States of Burma to the Langkawi Islands in Malaysia. The sediments, which are rich in quartz, were derived from a continental area and deposited on its margin. In contrast to previous interpretations of the Palaeozoic history of Peninsular Thailand, it is considered that the continental source lay to the east. The continental margin resembled modern margins of either Atlantic or Japan Sea type.
Depositional Features of Dittonian Rocks: Pembrokeshire compared with the Welsh Borderland
Authors: Allen J. R. L. 
Published: May 2009

AbstractThe Dittonian Stage in Pembrokeshire comprises the Lower Marl Group (higher beds), the Sandstone-and-Marl Group, and the Upper Marl Group (at least lower half). These formations cannot be distinguished lithologically from Dittonian strata of the Welsh Borderland 100 miles away along the depositional strike.Cyclothems of intraformational conglomerate (scoured surface below) → sandstone → siltstone with concretions recur vertically in each area. The conglomerates in both districts consist of intraformational siltstone and concretionary debris. Flat-bedding, primary current lineation, planar cross-bedding, trough cross-bedding, and ripple-drift bedding are common to the sandstones. Suncracked siltstones abound in both Pembrokeshire and the Welsh Borderland. Slumped bedding, sandstone pipes, and animal burrows are the structures penecontemporaneous with deposition in each area.The Dittonian strata of the Welsh Borderland are shown to be probably floodplain deposits, by reason of their close similarity to the modern sediments of the Colorado Delta floodplain and Colorado River. The occurrence of an identical facies in Pembrokeshire suggests the even wider extent of this floodplain in early Lower Old Red Sandstone times, when the sea lay far to the south of both areas.
Analysis of the Strike Swing at Crockator Mountain, co. Donegal, Eire
Authors: Rickard M. J. 
Published: May 2009

AbstractA detailed analysis is presented of a small complex bent-fold structure that occurs in the angle of the Donegal Granite outcrop. It is the most northerly expression of the major strike swing in South-West Donegal and may be of considerable importance to the interpretation of that phenomenon. Five different lineation types are related to events leading to the severe bending of a curved tight syncline in massive quartzite. The bending occurs with surprisingly little disruption of the quartzite and must have occured under plastic conditions possibly associated with granite intrusion.
Natrojarosite and ‘collophane’ in graphite-sillimanite-schist
Authors: Kempe D. R. C. 
Published: May 2009

SUMMARYSome graphite-sillimanite-schists and -gneisses, containing natrojarosite and ‘collophane’, from north-east Tanzania, are described, with an analysis, and their sedimentary origin briefly discussed.
Gneisses in the north-western part of County Mayo, Ireland
Authors: Sutton J. S. , Max M. D. 
Published: May 2009

SUMMARYA metamorphosed complex of basic and acid gneisses, which occurs in north-west County Mayo, Ireland, structurally underlies younger Moinian and Dalradian type metasediments. These gneisses are compared directly with the Lewisian ‘inliers’ of the western Highlands of Scotland.
Notes towards a theory of concentration of solids in natural sands
Authors: Allen J. R. L. 
Published: May 2009

SUMMARYTheory based on the sphere as the ideal particle, fails to account satisfactorily for the concentration of solids observed in unconsolidated natural sands, which at the same time display a substantial degree of dimensional ordering of the particles. However, when the prolate spheroid of moderate axial ratio is substituted for the sphere, a theory which is satisfied by observation becomes possible, for the reason that equal spheroids can be regularly packed in both close and open ways. A spheroid assemblage of mixed open and close packings can retain a high degree of dimensional ordering of the constituent solids, yet have a relatively low particle concentration. Observations made on sandstones carefully selected for evidence of rapid cementation seem to bear out the theory as applied to natural sands. Clusters of grains resembling the open packings of equal spheroids are found in these sandstones to be uncommon but not rare, in accordance with the theory as thus far developed.
Early Tertiary Fold Movements in Mull
Authors: Cheeney R. F. 
Published: May 2009

AbstractEvidence is presented which suggests that there is a strong angular unconformity between the Mesozoic sediments and the Tertiary lavas in certain parts of the Island of Mull. The conclusion is drawn that folding movements peripheral to the volcanic centre occurred both before and after the eruption of the main lava succession.
A Suspected Spilitic Rock from the Lower Cambrian Manganese Shale Group of the Harlech Dome, North Wales
Authors: Mohr P. A. 
Published: May 2009

AbstractMineral and chemical evidence suggest that an unusual rock from the Upper Manganese Shales of Diphwys is of spilitic origin, despite certain geochemical anomalies. Some similarities of the rock to the shales themselves are only superficial, and a metasomatic origin is precluded; the rock is also very distinct from the “greenstone” sills of the region.
Some Theoretical Factors in Geomorphological Analysis
Authors: Kennedy W. Q. 
Published: May 2009

AbstractConsideration of the relative rates of uplift-erosion and erosion-denudation leads to the recognition of nine cases which define the conditions of geomorphological evolution. It is concluded that a peneplanated surface may develop during active tectonic uplift, and that the total volume of clastic sediments produced during any stage is inversely proportional to the rate of uplift.
The Buried Channel of the Bristol Avon
Authors: Hawkins A. B. 
Published: May 2009

AbstractThe paper discusses the buried channel of the Bristol River Avon. Borehole information indicates a buried channel to a depth of at least — 65 feet O.D. in the Avonmouth area. This has been correlated with other areas and suggests an erosional date of the First or Second Buried Channel Period of the Last Glaciation.
Clarification of the Polyphase Deformations of North Wales Palaeozoic Rocks
Authors: Lynas Bryan D. T. 
Published: May 2009

SummaryRecent detailed mapping to the north-east of the Harlech Dome in North Wales has produced clear evidence of an early deformation. Thus four distinct deformations can be recognised in the Welsh Caledonides, and their resultant structures are described.
Morphology of Quaternary phonolite lavas from Tenerife, Canary Islands
Authors: Ridley W. I. 
Published: May 2009

SummaryPhonolite lava from the Viejo and Teide volcanoes show a wide variation in flow morphology, from viscous, spoon-shaped lavas to thin flows more than 8km long that often show well developed lava channels. The apparent fluidity of these lavas is considered to be largely due to their strongly alkaline character.
Notes on some deformation structures of sedimentary origin in the Little Haven—Amroth coalfield, Pembrokeshire
Authors: Williams Peter F. 
Published: May 2009

SUMMARYThe morphology, origin, and orientation patterns of distinctive types of sedimentary deformation structure are considered. The structures described are laminar folds, load marks and pouches, and convolute and corrugated lamination. A set of criteria obtained from detailed field analysis of the structures is put forward to indicate minor lateral translations of mobilised sediment.Laminar folds occur in a laminated mudstone/siltstone lithology and are the result of predominantly lateral movements in response to an unstable palaeoslope. Laminar folds are metadepositional or postdepositional in origin. Orientation patterns are characteristically unimodal. Load marks and pouches are preserved in a banded siltstone/sandstone-mudstone lithology, and result from sediment movements which are either vertical, or vertical with some lateral translation. They are syndepositional or metadepositional in origin. Orientation patterns are predominantly unimodal but bimodal and random patterns are also present. Convolute and corrugated laminations are found in thin siltstone/sandstone beds and have developed through sediment movements which were almost exclusively vertical. The convolutions and corrugations are metadepositional in origin. The majority of orientation patterns are unimodal but there is an increase in the number of random patterns.The positioning of deformation units which show internal lateral translation in a broader stratigraphical and geographical context, suggests there may be a regional palaeoslope control on the lateral movement of mobilised sediment.
Age of the Jamaican Granodiorite
Authors: Chubb L. J. , Burke Kevin 
Published: May 2009

AbstractGranodiorite intrusions in Jamaica were assigned by early workers to various ages from Pre-Cambrian to late Tertiary. Recent surveys have shown that the granodiorite intrudes Maestrichtian sediments and has provided material for pebbles in an Eocene conglomerate. Its age is therefore very late Cretaceous or very early Tertiary. Radio-metric determinations using Potassium/Argon; Rubidium/Strontium and isotopic lead methods suggest an age of 65 ± 5 million years.
Differing Powers of Crystal Nucleation as a Factor Producing Diversity in Layered Igneous Intrusions
Authors: Wager L. R. 
Published: May 2009

AbstractTo account for a type of rhythmic unit found in the Bushveld complex of South Africa and probably in other layered intrusions, a hypothesis is put forward dependent on the different powers of crystal nucleation from supersaturated magma. It is suggested, for example, that the three common primary precipitate minerals, chromite, bronzite, and bytownite nucleated in this order which is probably dependent on the differing complexity of their crystal structures and that the common rhythmic unit, beginning with chromitite, passing upwards into bronzitite and ending with a bytownite-rich rock is the result of these crystals accumulating successively at the bottom'of the liquid.
Greywacke Sedimentation in the Torridonian of Colonsay and Oronsay
Authors: Stewart A. D. 
Published: May 2009

AbstractThe lower Torridonian in its southernmost outcrops is built of felspathic greywacke turbidites, forming a succession probably 2–3 km. thick, overlain by 2 km. of pelitic and semi-pelitic sediments containing thick, current-bedded pebbly arkose horizons, especially near the base. Sedimentary structures in the greywackes include ubiquitous grading, together with flames, load-casts, convolute bedding, and sedimentary injection, brecciation and disruption phenomena. Palaeocurrents in both greywackes and arkoses indicate a southerly derivation. The detrital mineralogy also suggests a common provenance. It is suggested that the greywackes gradually filled their depositional basin and that later sedimentation occurred in a shallow water or fluvial environment.
A Drift-filled Valley at Thistleton on the Rutland–Lincolnshire Border
Authors: Rice R. J. 
Published: May 2009

AbstractA borehole programme by Stewarts and Lloyds Minerals, Ltd., has shown that a narrow tongue of boulder clay conceals a deep steepsided valley cut into the Lincolnshire Limestone and filled with drift. Plotting of structure contours indicates that, even where thedrift is more than 100 feet thick, there is considerable “bulging” of the Upper Lias Clay.
The Geometry of Conjugate Fold Systems
Authors: Ramsay John G. 
Published: May 2009

AbstractConjugate shear fold systems are often developed when brittle laminated rocks are subjected to stress. These structures relationship of the principal axes of stress to the surface being folded. Within first order shear zones conjugate second order shear folds may be developed as a result of reorientation of the stress axes in these zones.The axes of both first and second order conjugate shear folds may form at any angle to the principal stress axes and to the direction of movement within the shear zones. The principal axes of stress are most reliably determined from the orientation of the axial planes of the first order conjugate folds.