bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oolites and deformation
Authors: Kumar Surendar 
Published: May 2009

SummaryA study in the deformational patterns of oolites from the Krol Series of the Simla Himalayas has been made in the type area. The deformation in the oolites is the result of the tectonic phenomenon coupled with folding movements during the Himalayan orogeny. The deformation varies with the amount and type of the matrix surrounding the oolites. The angle between the long axis of the ellipse and the principal tectonic extension is smallest in the axial regions of the folds.
The quartz-plagioclase gneisses of Western Connemara, Ireland
Authors: Benjamin R. E. K. 
Published: May 2009

SUMMARYChemical analysis of twenty-six amphibolite facies gneisses from western Connemara are treated statistically, and used in conjunction with petrographic evidence to elucidate their origins. It is shown that the gneisses are of igneous ancestry, and have been invaded by material of silica-soda potash composition. The conditions of temperature and pressure prevailing at different times is related to the evolved mineral assemblages, and the whole sequence fitted into the general pattern of events in Connemara.
On Pyroxene Molecules in the CIPW Norm
Authors: Chayes F. 
Published: May 2009

AbstractBarth argued that the CIPW conventions governing the calculation of normative pyroxenes and olivines are based upon inadequate or incorrect mineralogical information and should be abandoned. The real occasion for the conventions appears to be petrological, not mineralogical. Qualitative agreement between norms and modes of undersaturated rocks requires the use of these or very similar conventions. Ease of calculation is no longer a major consideration and a more realistic set of rules could now be adopted if it were available.
A Possible Fossil in a Graphitic Marble in the Connemara Schist, Cornamona, Co. Galway, Ireland
Authors: Leake Bernard E. 
Published: May 2009

AbstractA network texture made of graphite with calcite filling the holes is described from an area of staurolite-garnet grade of metamorphism. It is pointed out that this is the earliest texture preserved in the rock, and that it resembles a cellular structure and may therefore be of organic origin, possibly a primitive plant. At present, however, it is not certain that the structure is organic in origin.
On the Occurrence of Two Intersecting Pre-Cambrian Orogenic Belts in Singhbhum and Adjacent Areas, India
Authors: Sarkar S. N. , Saha A. K. 
Published: May 2009

AbstractIntensive structural and stratigraphic studies, supplemented by nine new absolute age data, have led to the recognition of two distinct orogenic belts in the Pre-Cambrian tract of Singhbhum and adjacent areas in India. The Iron Ore orogeny in the south, characterized by the generally low grade metamorphic, N.N.E.–S.S.W. trending formations, had its culmination in the emplacement of the batholithic body of Singhbhum granite (c. 2,000 m.y.). These rocks are separated by a prominent thrust zone (Copper Belt thrust) from the E.–W. striking, generally high-grade meta-morphic rocks of the Singhbhum orogeny whose closing age is 905 to 934 m.y.
Pyrothalassite and the evolution of volcanic islands
Authors: Middlemost Eric A. K. 
Published: May 2009

SummaryIt is proposed that the term pyrothalassite should be used to describe the materials that form the outer and upper covering of a volcanic edifice that rises from the sea bed, and it includes the fragmental materials produced by hydroexplosions and surf action in the upper layers of the sea. This material is both porous and enriched in thalassophile elements. These two characteristics give a pyrothalassite layer the ability to exert a profound influence on the magmatic evolution of volcanic islands that contain, or contained, such a layer.
The Caledonoid faults of northern Lleyn (North Wales)
Authors: Tremlett W. E. 
Published: May 2009

SummaryEvidence of substantial dextral strike-slip displacements along the Caledonoid fault-set of northern Lleyn is revealed by the distribution of Pre-Cambrian igneous and metamorphic rocks, Ordovician volcanic rocks and Caledonian ‘early granodioritic’ intrusions. These apparently occurred prior to some smaller sinistral strike-slip movements which left total net dextral displacements of 91/2 km. Both types of movement were completed before the Caledonoid faults were disrupted by NNW sinistral faulting and more intrusions of Lower Old Red Sandstone age were emplaced.
A Pyroxene – Hornfels from the Basic Plutonic Complex, Co. Tyrone, Ireland
Authors: Angus N. S. 
Published: May 2009

SummaryA basic augite-hypersthene-hornfels, which escaped a subsequent regional amphibolite facies metamorphism, is preserved adjacent to a gabbroic intrusion of the Basic Plutonic Complex. The hornfels and two dolerites have been analysed and their compositions compared with similar rocks from Duluth and Skye. It appears that Si, Na and K have been removed from the dolerites, and the resultant hornfels relatively enriched in Fe, Mg, Ti and Ca.
Linear sole markings in Pleistocene till
Authors: Westgate J. A. 
Published: May 2009

SUMMARYCurrent-produced sole markings are not uncommon in the Pleistocene continental till deposits of Alberta, Canada. Groove, striation and prod moulds have all been recognized, characteristically occurring in close association on the undersurface of the till beds. These sedimentary structures provide a rapid means by which local ice-flow directions may be determined.
Note on radiometric age determination of samples of peat and wood from tin-bearing Quaternary deposits at Sungei Besi Tin Mines, Kuala Lumpur, Selangor, Malaysia
Authors: Haile N. S. , Ayob Mohammad Bin 
Published: May 2009

SUMMARYA radiometric age determination on wood in tin-bearing alluvium from Selangor gives a result of about 36,000 years B.P. This is consistent with the view that the deposits formed during a period of rejuvenation of river systems during the Pleistocene. Meagre palynological evidence indicates the deposit is late Pliocene or younger.
A Pre-Cambrian Glass from St. Alexis-des-Monts, Quebec
Authors: Philpotts A. R. , Miller J. A. 
Published: May 2009

AbstractThe Pre-Cambrian rocks north of Three Rivers, Quebec, are cut by a major fault in which glassy pseudotachylites have been developed. The glass, which is dark brown in thin section, has a specific gravity of 2.76 and a refractive index of 1.567. It has a similarcomposition to the quartz monzonite in which it occurs. Absolute dating by the potassium-argon method indicates that the glass is 975 million years old. The persistence of thisglass indicates how sluggish devitrification can be when the environment is cool and dry.
A second specimen ofOsculocystisPaul 1967
Authors: Paul C. R. C. 
Published: May 2009

SummaryA second specimen ofOsculocystisconfirms that the genus occurs in the Upper Llandovery (Purple Shales) near Buildwas, Shropshire and adds information on morphology. The subvective system consists of a single long brachiole; the stem lacks a root structure. The mouth, gonopore and hydropore are described and the three pectinirhombs B2:IL2, L2:R1 and L4:R3 are confirmed.
The origin of some transverse sand patches in the Celtic Sea
Authors: Kenyon N. H. 
Published: May 2009

SummaryTransverse sand bodies of a new type from the continental shelf are commonly 2m high, 500m long and crescentic in plan view. They are believed to be transported at the present day by weak tidal currents (approximately 1 knot peak velocity near the surface) associated with wave induced oscillatory water movements of similar strength, rather than being formed near the shores at times of lower sea level.
Cone-sheets as a mechanism of uplift
Authors: Le Bas M. J. 
Published: May 2009

SummaryBy the study of dilation associated with cone-sheet emplacement and the deformation of the basal Carboniferous unconformity at the Irish Tertiary igneous centre of Carlingford, it is shown that cone-sheets are capable of producing considerable uplift. This process is also the cause of the steep-sided domes which occur at some carbonatitic centres in Kenya.
Feldspathic vent agglomerates at Bukusu, Uganda—a reinterpretation
Authors: Baldock J. W. 
Published: May 2009

SummaryFeldspathic agglomerates and related tuff-like rocks occurring at the Bukusu carbonatite complex were long thought to have been deposited as pyroclastics during a later (Elgon) period of volcanism. Evidence is presented for a reinterpretation of these rocks as vent agglomerates and tuffisites emplaced in the central diatreme of this large, pre-Elgon, complex.
The origin of some collapse structures in the Canary Islands
Authors: Ridley W. I. 
Published: May 2009

SummaryThree large collapse structures, two bounded by straight, vertical escarpments and curved head regions, are described from Tenerife. Similar structures appear to exist on Hierro and La Palma. Their size precludes landsliding as the dominant force in their formation, although it may have played a minor role in modifying the bounding walls. It is suggested that these structures are true volcanic collapse features developed by a ‘trap-door’ type of mechanism. The lack of classical caldera shapes appears to be a reflection of a lack of well-defined central volcanism on any of the islands, the collapses probably resulting from migration of magma away from the central rift-zones towards the flanks of the islands.
Monograptus priodon (Bronn) from the Macduff Group (Upper Dalradian) of Banffshire, Scotland
Authors: Skevington D. 
Published: May 2009

SummaryTwo incomplete graptolite rhabdosomes in the Hugh Miller Collection (Royal Scottish Museum) are referable to Monograptus priodon (Bronn). The specimens were obtained from the Macduff Group, the youngest member of the Upper Dalradian succession in Banffshire (Read, 1923). This occurrence extends the upper stratigraphical range of the Dalradian Series into, at least, the Lower Silurian and possibly into the lowermost part of the Upper Silurian.
Pleistocene superficial deposits, Balcombe area, central Weald
Authors: Piper D. J. W. 
Published: May 2009

SummaryPleistocene silty mudflow deposits mantle much of the valley sides and floors of the Balcombe area of the central Weald. Boulder deposits at the foot of cliffs formed of resistant bedrock sandstones are also of Pleistocene age. One well sorted sand from a gentle valley side shows surface grain textures under the scanning electron microscope indicative of wind action. The superficial deposits formed under periglacial conditions, and their distribution indicates most of the landforms are relict Pleistocene features.
Metamorphosed rugose corals in Devonian Limestone, at Calcium, North Queensland, Australia
Authors: Morgan W. R. , Perrott I. H. , Petherbridge R. T. 
Published: May 2009

SummaryContact metamorphosed rugose corals now consist of sub-radiate to sub-parallel fibres of wollastonite. It is considered that they result from the recrystallization of corallites that were partly silicified during diagenesis.
Washout Structures in the Dalradian near Kentallen, Argyll
Authors: Bowes D. R. , Wright A. E. 
Published: May 2009

AbstractThe occurrence of numerous washout structures in the Appin Quartzite is recorded and the criteria by which they are recognized discussed. It is concluded that these structures are reliable for the determination of the way-up of beds and that their association with current and graded bedding indicates a turbid deltaic environment of sedimentation.
Turbidity Current at Kadavu Passage, Fiji
Authors: Houtz R. E. , Wellman H. W. 
Published: May 2009

AbstractThe 1953 earthquake at Suva in the Fiji Islands caused submarine subsidence at the outer edge of the coral reef near Suva. Sixty miles of the cable from Suva to Norfolk Island was either buried or shifted about 2 miles from its original position. The damaged cable followed close to the centre of a submarine valley that extends out from the coral reef near Suva. A length of cable recovered from the ocean bottom 40 miles from Suva is damaged in a way that indicates that it was eroded while lying partly buried in sediments and was then torn up and twisted. A wire hawser found attached to the cable had been cleaned by sandblasting. It is inferred that the cable was damaged by a turbidity current that originated at the submarine subsidence, that the current had a velocity of at least 10 miles an hour, and that it travelled for at least 70 miles.
Clay Mineralogy of Selected Clays from the English Wealden
Authors: Tank R. W. 
Published: May 2009

AbstractX-ray analyses of selected samples from the argillaceous subdivisions of the English Wealden indicate that illite, kaolinite, and mixed-layer structures are present in variable amounts. The clay mineral assemblage is thought to reflect parent material, weathering conditions in the source area, and possibly some degrading of the illite structure by the action of active waters in the depositional environment. The specific clay minerals are tentatively correlated with the palaeogeographical framework proposed by Allen (1954). It is suggested that the kaolinite was derived mainly from the Palaeozoic uplands, and the bulk of the illite and mixed-layer structures from the marginal Jurassic lowland.
Sedimentary Structures in the Keuper Marl (Upper Triassic)
Authors: Klein George DeVries 
Published: May 2009

AbstractCombinations of sedimentary structures in the lacustrine Keuper Marl are segregated bathymetrically. Beds deposited below lacustrine wave base are characterized by even bedding, rhythmic lamination, disturbed stratification, graded bedding, load casts, “pull-apart” structures, and oscillation ripple marks. Lacustrine beds deposited above wave base contain even bedding, rhythmic lamination, oscillation and interference ripple marks, current lineation, rib-and-furrow structure, groove casts, mudcracks, and raindrop imprints.A marine unit in the Keuper Marl is characterized by even bedding, flat-topped oscillation ripple marks, and air-heave structures.Comparison with sedimentary structures of other known lacustrine deposits suggests that the combination of structures in the non-marine Keuper Marl is diagnostic of lacustrine deposits. Recognition of such combinations of sedimentary structures should aid in interpreting the origin of continental sequences.
The Geology of the Katmaian Volcanics of the Upper Oramutia Valley, Kenya
Authors: Bristow C. M. 
Published: May 2009

AbstractThe Oramutia volcanics consist of a group of ignimbrites overlain by pumice tuffs, which lie in a fault formed valley on the eastern flank of the main Kenya rift valley. The presence of a dyke of ignimbrite suggests that the “claystone ” ignimbrite of this area was erupted from fissures. A similar explanation probably applies to the pumice tuffs. These volcanics are therefore the product of Katmaian type eruptions.
The Gneisses of the Bartica Assemblage, British Guiana
Authors: Cannon R. T. 
Published: May 2009

AbstractThe results of an examination of one quarry within the gneisses of the Bartica Assemblage are described and the validity of these results throughout the whole of the Bartica Assemblage is discussed. The foliation and banding of the gneisses at Kereti Quarry are mainly the results of tectonism; concomitant metamorphism within the Amphibolite Facies was succeeded by a two-phase metasomatism involving successive additions of Na and K. These results appear valid throughout the Bartica Assemblage and it is further suggested that the main rock type distribution in the Bartica Assemblage is also controlled by tectonism.
Shape and size trends for sand waves in a depositional zone of the North Sea
Authors: Stride A. H. 
Published: May 2009

SummaryA continuous profile of 430 large sand waves shows a progressive decrease in height (with some increasing crest separation) in their inferred migration direction, as well as showing the changing effectiveness of the ebb and flood tidal currents to move sand. The height of these and other sand waves around the British Isles is virtually unrelated to the depth of the sea, contrary to what has been suggested elsewhere. However, most sand waves occur on the continental shelf broadly because it is there that the currents reach a suitable range of speeds and sufficient sand is available at the present time.
A Miniature “Dyke” Echelon
Authors: Gilliland William N. 
Published: May 2009

AbstractA specimen of shale containing an echelon of quartz-filled vertical tension fractures which merge “at depth” with a single filled fissure dipping 65 degrees confirms, in general, E. M. Anderson's interpretation of dyke echelons. Also illustrated are a change in manner of stress relief and an upward diminution of strain.
A mega-porphyritic dolerite on Long Island, Seychelles Archipelago
Authors: Frankel J. J. 
Published: May 2009

SUMMARYA dolerite intrusion on Long Island, Seychelles contains exceptionally large plagioclase (labradorite) phenocrysts essentially unzoned, set in a doleritic groundmass. Many of the mega-phenocrysts have a dark redbrown interior.In the groundmass, zoned plagioclase is in a doleritic texture with a slightly titaniferous ferro-augite that has been almost completely replaced by an actinolite uralite.The mega-phenocrysts are considered to have crystallized slowly at depth and concentrated locally in a chamber of basaltic magma. The portion of magma containing these plagioclase crystals was later injected to higher levels as dykes. Although emplaced in a granitic (continental) environment, the intrusion has oceanic basalt affinities, and in chemical composition resembles high alumina basalts.
The Evolution of Gryphaea
Authors: Philip G. M. 
Published: May 2009

AbstractThe coiling of the Liassic oyster Gryphaea is discussed and the assessment of tightness of coiling investigated. Hence Hallam's (1960a, b) statistical work on Gryphaea is interpreted and from his original measurements a highly significant increase in thetightness of coiling is demonstrated in the Gryphaeas of the higher Sinemurian horizons of Britain. The presence of a strong natural selection pressure favourable to more tightly coiled individuals of the communities is indicated, and the nature of the lineage discussed. It is suggested that recent criticisms of Trueman's work lack foundation.
The Composition of Marls and Limestones in the Great Oolite Series of Oxfordshire
Authors: Sugden W. , McKerrow W. S. 
Published: May 2009

AbstractAnalyses of eighteen samples from Jurassic marls and limestones show a large, continuous range in carbonate-clay composition. The significance of the carbonate/clay ratio is discussed, and it is show that rapid lateral and vertical transitions from marl to limestone may either reflect major changes in composition or represent only small shifts (across a critical value: 4) in the carbonate/clay ratio. The term “marl” is defined.
The Highland Border Ridge of North-east Ireland
Authors: Sanderson D. J. 
Published: May 2009

SummaryThe Highland Border Ridge is a present day positive physiographic element whose activity can be traced back to Devonian time. A change from a distant Lower Dalradian to a nearby Middle and Upper Dalradian source area during Lower Old Red Sandstone times reflects the initial development of the ridge. A model for ridge uplift is outlined and some of its implications discussed.
Metamorphism of Caledonian Metadolerites in North-west County Mayo, Ireland
Authors: Max M. D. 
Published: May 2009

SummaryCaledonian dolerite dykes in northwest County Mayo, Ireland, are differentially metamorphosed with volumes of largely unmetamorphosed dolerite grading into marginal amphibole schists with no preserved igneous textures. Deformation controlled the extent of the metamorphism. The lack of a significant differential strain in the volumes of preserved igneous rock is considered to be the cause of the preservation.
Significance of lineation and minor folds near major thrust faults in the southern Appalachians and the British and Norwegian Caledonides
Authors: Bryant Bruce , Reed John C. 
Published: May 2009

SUMMARYThe Blue Ridge thrust sheet is one of the principal thrust masses of metamorphic rocks in the southern Appalachians. A broad zone of sheared and retrogressively metamorphosed rocks near the sole of the thrust sheet around the Grandfather Mountain window displays numerous small tight or isoclinal folds having axes subparallel to an intense penetrative cataclasticalineation and axial planes parallel to foliation in the thrust sheet. These folds seem to have formed by tightening, flattening, and passive rotation of earlier more open folds originally formed perpendicular to the direction of transport. The style and orientation of these folds closely resemble those of analogous structures in thrust masses of crystalline rocks in the Caledonian orogenic belt in Scotland and Norway, suggesting that the structures of both regions may have similar origins.
An Upper Llandovery limestone overlying Hollybush Sandstone (Cambrian) in Hollybush Quarry, Malvern Hills
Authors: Jones R. K. , Brooks M. , Bassett M. G. , Austin R. L. , Aldridge R. J. 
Published: May 2009

SUMMARYNew exposures of Upper Llandovery and Cambrian strata are described from the southern Malvern Hills. The rocks occur in a small faulted outlier between Midsummer and Hollybush Hills, within the main Pre-Cambrian outcrop. The Cambrian is represented by a thin succession of Malvern Quartzite and Hollybush Sandstone and is overlain by an Upper Llandovery limestone with a basal conglomerate containing rounded pebbles of Hollybush Sandstone. The new exposures weaken the case for a major post-Llandoverian fault at the western boundary of the local Pre-Cambrian outcrop, but provide further evidence of an important phase of pre-Llandoverian tectonism in the Malvern area.Faunas of brachiopods, graptolites and conodonts from the Llandoverian limestone allow a correlation with the C5 substage of the shelly sequence, the griestoniensis graptolite zone and a position near the boundary of the celloni and amorphognathoides conodont zones.
The Petrology of a Teschenite Sill at Landywood, Staffordshire
Authors: Barton M. E. 
Published: May 2009

AbstractBorehole cores have been obtained of a basic igneous sill at Landywood, near Cannock, Staffordshire. This intrusion consists mainly of microteschenite with a zone of teschenite in the top half of the sill. Later parts of the parental magma of this intrusion were dryer and crystallized to give crinanite and analcite olivine dolerite. These later parts were not intruded in sufficient quantities to spread through the whole of the sill and were restricted to the vicinity of the feeding pipe. Extensive secondary replacement of plagioclase by chlorite and of pyroxene by carbonate occurs in the teschenitic parts of the sill and is ascribed to the action of water and carbon dioxide derived from the magma.
Volcanic and Associated Rocks in the Coal Measures of Colston Bassett (South) Borehole, Nottinghamshire
Authors: Sabine P. A. 
Published: May 2009

SummaryThe BP Exploration Company's Colston Bassett (South) No. 1 Borehole, Nottinghamshire, entered Coal Measures at 1,134 feet. These persisted for 901 feet, when massive tuffs were encountered which were 679 feet thick and overlay Millstone Grit. The tuff is composed of amygdaloidal glass, devitrified to a montmorillonite, and is rich in analcime. In a nearby borehole, no tuffs were encountered and the Coal Measures were 1,784 feet thick. It seems that at Colston Bassett (South) the lowest Coal Measures sediments are represented by the tuff, which is non-displacive and was perhaps a cone against which the later sediments were deposited.
A Note on the Crag in Norfolk
Authors: Downing R. A. 
Published: May 2009

AbstractIn East Norfolk, boreholes have revealed the presence of a northern and a southern clay bed in the Crag. These lie at different horizons and have been linked to clay exposures previously correlated with the Chillesford Beds of Suffolk. It is concluded that a clay facies is developed at two main horizons in the Crag in Norfolk.