bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stage Names within the Llandovery Series
Authors: Cocks L. R. M. , Toghill P. , Ziegler A. M. 
Published: May 2009

SummaryFour stage names are erected within the southern part of the type area of the Llandovery Series, south-east of Llandovery, Carmarthenshire, Wales. They are Rhuddanian, to incorporate the existing Lower Llandovery; Idwian for the Middle Llandovery, and Fronian and Telychian for the Lower and Upper parts of the Upper Llandovery. Correlation with the sequence of graptolite zones is suggested.The base of the Llandovery at Llandovery is poorly exposed and unfossiliferous, and detailed correlation with other areas may always remain uncertain. Thus the base of the Llandovery Series, and hence the base of the Silurian System, is defined in Lapworth's classic locality at Dobb's Linn, Moffat, Scotland, at the base of the zone of Glyptograptus persculptus.
Petrology of acid xenoliths from Surtsey
Authors: Sigurdsson Haraldur 
Published: May 2009

SUMMARYA number of acid plutonic xenoliths from the volcano Surtsey are described, along with fine-grained rock fragments, consisting chiefly of anorthitic plagioclase and tridymite. The chemistry of the xenoliths indicates a compositional pattern from tonalitic to pyrometamorphic types. A hypothesis is put forward that the tonalitic xenoliths have undergone partial fusion during transport to the surface in the basaltic magma, and the removal of a salic liquid from granitic xenolith into the magma has resulted in the formation of a residue of anorthitic plagioclase and tridymite. Granitic xenoliths from other parts of Iceland, and their fusion products, are also described.
Coleoptera from the “Arctic Bed ” at Barnwell Station, Cambridge
Authors: Coope G. R. 
Published: May 2009

SUMMARYRemains of coleoptera collected by Miss Chandler from the Barnwell Station beds (Cambridge) are described. Twenty-one recognizable taxa are recorded, all of which represent living genera or species. Five species are no longer found living in Britain and are confined today to arctic or sub-arctic environments. This interpretation of the fauna is in marked contrast to the identifications of P. Lesne, whose manuscript determinations are attached to the slides. He had attributed many of the specimens to new genera and species.The fauna as here interpreted indicates a truly tundra environment and qualitatively and quantitatively resembles very closely other British coleopteran assemblages from the latter part of the Upton Warren (Mid-Weichselian) interstadial, i.e. about 30,000 years B.P.
A Columnar Crystallization of Olivine and Plagioclase
Authors: Preston J. 
Published: May 2009

AbstractA thin vein of dolerite at Slemish, Co. Antrim, shows an unusual plane and smooth contact against the dolerite of a Tertiary plug. A columnar growth at the contact indicates special conditions for crystallization. The selvedge is described and an attempt made to explain the growth and orientation of the olivine.
Some Investigations of the Roraima Formation Intrusives in British Guiana
Authors: Rust B. R. 
Published: May 2009

AbstractA traverse of a noritic gabbro sill (c. 1,000 feet thick) intruding the Roraima Formation showed no cryptic layering, but small-scale fractionation throughout the sill is indicated by the strongly-zoned plagioclase (An80→40), and orthopyroxene (En79→54) with outer rims of inverted pigeonite. Olivine (Fo80) is only present in the chilled margin.New evidence on the age of the granites underlying the Roraima Formation is given by the discovery of post-Roraima felsite dykes, with high-quartz phenocrysts.
An Occurrence of Regionally Metamorphosed Pre-Cambrian Schists in South-West Pembrokeshire
Authors: Claxton C. W. 
Published: May 2009

AbstractRecent research work has revealed an area of regionally metamorphosed Pre-Cambrian schists (previously undescribed) in south-west Pembrokeshire. The name “Dutch Gin Schists” is proposed for this newly described group of rocks. The Johnston Plutonic Series (Dimetian) are seen to be intruded into these schists, and the nature of the intrusive contact is described. The structure and petrology of the schists, and the nature of diorites adjacent to the contact and that seen elsewhere in the igneous mass is compared, and a suggestion made regarding the age of the foliation. A comparison is made with the Pre-Cambrian metamorphosed rocks of Malvern, Shropshire, and Anglesey.
The palaeogeographical significance of lateral variations in the ratio of sandstone to shale and other features of the Aberystwyth Grits
Authors: Lovell J. P. B. 
Published: May 2009

SummaryStatistical sampling of the Aberystwyth Grits, using a method previously employed in an analogous study of Tyee Formation, Oregon, shows an overall decrease in the ratio of sandstone to shale from south-west to north-east, away from the supposed source of depositing currents. Comparison with other methods of proximality evaluation in turbidite sequences indicates that at least in this case the ratio of sandstone to shale is the most sensitive indicator of palaeogeography.
The structural characteristics of the Strathspey Complex, Inverness-shire
Authors: Smith T. E. 
Published: May 2009

SummaryA detailed account is given of the structural features of the Strathspey Granite and Pegmatite Complex together with information about the metamorphic and tectonic environment of the surrounding metasediments. The evidence indicates that the granite core of the complex was intruded shortly after the latest phase of folding recorded in the area had taken place. The country rocks were still at relatively high temperatures at the time of intrusion and were deformed by the granite. The granite emplacement is also shown to be a separate event not directly connected with the formation of the regional migmatite complex, which extends for 48 km to the north-east.
Transcurrent faulting in the Sarawak-Kiri region, Sarawak, East Malaysia
Authors: Tjia H. D. 
Published: May 2009

SummaryGeological discontinuities, lineaments, field observations, and interpreted π-girdles demonstrate a left lateral, NNW trending transcurrent fault in the Sarawak-kiri valley of West Sarawak. Topography and geology also suggest that the fault belongs to an important fracture zone that extends well into Indonesian Kalimantan, and continues in a northerly direction along the edge of the Sunda Shelf beneath the South China Sea.Comparison with transcurrent faulting occuring in the Malay Peninsula and a probable wrench fault between Palawan island and Sabah (North Borneo) reveals the continental part of southeast Asia to have rotated counter-clockwise up to Lower Palaeogene time, probably as a response to spreading of the Pacific ocean floor.
The Correlation of the Ballachulish and Perthshire (Iltay) Dalradian Successions
Authors: Rast N. , Litherland M. 
Published: May 2009

SummaryThe historical background of correlations between various Dalradian successions is examined, and on the basis of recent mapping and observations it is suggested that the Ballachulish succession is the downward extension of the standard Perthshire sequence.
Pebble surface textures
Authors: Krinsley David , Donahue Jack 
Published: May 2009

SUMMARYAn electron microscope examination of beach and glacial pebbles suggests that these two environments do not impress distinctively different textures on pebble surfaces. A detailed study of surface textures of beach pebbles indicates that size reduction is predominantly an abrasional rather than solutional process. The three textural features noted, flat planar surfaces, pits and arc-shaped fractures, were characterized by an abundance of mechanical breakage blocks slightly modified by solution. All three textural types were experimentally duplicated.
Spongolites from the Arnsbergian of County Limerick, Ireland
Authors: Lewarne Gillian C. 
Published: May 2009

AbstractSpongolite beds are common in the basal Namurian shales of Co. Clare and Co. Limerick, and are especially well developed north of Ardagh, Co. Limerick. Spongolites from this locality are described and are considered to represent a local deposit of siliceous monactinellid spicules. They are compared with the “phtanites” of the Assise de Chokier of Belgium, which are of the same age and similarly preserved. Stylolite seams developed within the rocks are briefly described.
Origin of ash deposits in the Santiago area, Central Chile
Authors: Guest J. E. , Jones G. P. 
Published: May 2009

SummaryNon-stratified, poorly-sorted rhyolitic ash deposits previously described as morainic and mudflow deposits are reinterpreted as ignimbrites emplaced in the topographically lower parts of the Santiago basin by pyroclastic flows. These flows probably originated from sources high in the Andes, and swept down the deep Maipo valley to spread out over the sediments filling the basin. An ignimbrite with a zone of dense welding but otherwise of similar character to the non-welded ashes of the basin occurs in one of the Andean valleys; and peculiar ‘pipe’ structures in the ashes of the basin support a pyroclastic flow origin.Further study of the nature and origin of these rocks may lead to a better understanding of the structural evolution of the area.
Callocystites brevis, a new Silurian rhombiferan cystoid from Indiana
Authors: Frest T. , Paul C. R. C. 
Published: May 2009

SummaryA new rhombiferan cystoid, Callocystites brevis, is described from the top 45 cm of the Laurel Limestone at Sandusky, Decatur County, Indiana. The species is known from a single crushed theca and many isolated plates. C. brevis is characterized by short, unbranched ambulacra. The subfamily Callocystitinae and the genus Callocystites are redefined.
Initiation of the Northumberland basin
Authors: Leeder M. R. 
Published: May 2009

SummaryA north-easterly palaeoslope is demonstrated for the south-eastern Scottish Borders during the Upper Devonian. Alkali basalt extrusion in the (?basal) Tournaisian was followed by initiation of the Northumberland basin as a structural feature. Basin subsidence gave rise to a south-easterly palaeoslope in the Southern Uplands and was coincident with the mid-Tournaisian marine transgression.
Some relations between common acid–basic associations
Authors: Roobol M. J. 
Published: May 2009

SummaryNet veined complexes and basic dykes with lobate or planar margins are commonly contained in granophyre and felsite. A study of three Tertiary centres reveals that the associations do not occur as distinct types but show gradational relations. Examples are used to illustrate a gradational morphological series. The interpretation of this series is best accounted for in terms of a basic magma invading an acid host. The factors considered capable of producing the described variations are (a) the volume of basic magma (and therefore amount of heat introduced), and (b) the degree of consolidation (ratio of crystals to melt) of the acid host.
Rate of uptake of calcium carbonate in underground karst water
Authors: Pitty A. F. 
Published: May 2009

SummaryA method of estimating the rate of flow-through time of water moving in an outcrop of massive limestone is reviewed. Mean values of calcium carbonate dissolved are shown to be proportional to flow-through times. The rate of uptake is very similar in both Derbyshire and Yorkshire. The pattern demonstrated resembled the relationship between salinity and increased depth noted for deep sub-surface brines.
Fossil Coccospheres from a Tertiary Outcrop on the Continental Slope
Authors: Black Maurice 
Published: May 2009

AbstractA soft chalky limestone or coccolith-marl, believed to form a submarine outcrop in the upper part of the continental slope off Brittany, consists largely of coccoliths, with subordinate quantities of foraminifera and sponge-spicules. Of the twenty or more species of Coccolithophoridae found in this deposit, two are preserved as complete coccospheres more frequently than as separate placoliths; these are described and named. The age of the rock is probably late Tertiary.
Biotite- and Sphene-rich rocks in the Moine Series of Ardnamurchan, Argyllshire
Authors: Butler B. C. M. 
Published: May 2009

AbstractSchists composed essentially of biotite and sphene have been found in many localities in the psammitic groups of the Moine Series in Ardnamurchan. From petrographic and chemical evidence it is concluded that they were heavy mineral bands, composed of sphene and iron oxides with a matrix which was partly pelitic and partly quartzo-feldspathic. This postulated original composition may have been produced by sedimentary slumping, for which field evidence is available. The unusual chemical composition was probably accentuated at higher grades of metamorphism by metamorphic metamorphic segregation, particularly a loss of soda or of segregation, particularly a loss of soda or of albite into the surrounding arkoses.
The origin of eclogite and ariégite nodules in basalt
Authors: O'Hara M. J. 
Published: May 2009

SUMMARYThe origin of eclogite nodules in basalt is reviewed in the light of experimental studies and the conclusion reached that many of them precipitated from basic magma as garnet-pyroxene accumulates at high pressure, although some may represent exsolved clinopyroxenite accumulates.
Sponges and the Chalk Rock
Authors: Reid R. E. H. 
Published: May 2009

AbstractChalk Rock lithology suggests shallow-water conditions, but the fauna has been said (Woods, 1897; Jukes-Brown, 1904) to imply a depth between about 100–500 fm. A study of the sponges which are numerous in the Oxfordshire–Hertfordshire area shows that these form a fauna of the sort which is typical of the Chalk as a whole, with Hexactinellida predominant as was pointed out by Woods; this is a fauna of deep-water type by both modern and Cretaceous standards. The depth which these sponges imply need, however, not be much more than 100 fm., and their presence need have no direct bearing on the depth at which erosional features were formed.
Tholeiite from the Simien alkali basalt centre, Ethiopia
Authors: LeBas M. J. , Mohr P. A. 
Published: May 2009

SummaryThe Ethiopian Cainozoic volcanics associated with the African rift system comprise one of the world's most voluminous alkaline igneous provinces. The Simien Mountains are the remnants of a Miocene alkali olivine-basalt volcanic centre in the north-western part of this province. The end-phase activity at Simien featured intrusion of dyke-swarms of two trends, one parallel to the rift system, the other almost perpendicular to it. Dykes of the rift trend are typically alkaline, but a dyke sampled from the other trend proves to be an olivine-tholeiite. Its presence is interpreted, along with similar rocks from the Harar region in eastern Ethiopia, in terms of upper mantle rifting extending from the Gulf of Aden and Red Sea under the continental blocks of the Ethiopian swell.
The Crush Zone of the Iranian Zagros Mountains, and its implications
Authors: Wells Alan J. 
Published: May 2009

SUMMARYAn early study of part of the Zagros mountains of south-western Iran put forward evidence for extensive overthrusting and nappe formation. A simplified interpretation of the stratigraphy now obviates the necessity for such tectonic complications.The north-eastern limit of Zagros folding is marked by a long narrow belt of structural deformity and stratigraphic discontinuity known as the Crush Zone, which includes basic intrusive rocks contemporaneous with the late Tertiary foldings.It is suggested that the Crush Zone is closely related to the Zagros orogeny, and geophysical evidence is used to speculate on a possible explanation. The general concept of the Crush Zone could prove to be of more widespread application.
The reptile Fauna Of The ‘Lower Keuper’ Sandstone
Authors: Walker A. D. 
Published: May 2009

SUMMARYPrevious records are revised, and new identifications of reptiles are presented, based on a study of specimensin older collections. Amphibious marine forms of Alpine Trias and Muschelkalk affinities are recognized from the Midlands, albeit on tantalizingly incomplete material. Such evidence as the reptiles provide indicates an early to mid-Ladinian age for the upper part of the Building Stones, the boundary between Anisian and Ladinian here being taken to lie within the Middle Muschelkalk.
Post-burial sideritisation of calcite in Eocene beds from the Maracaibo Basin, Venezuela
Authors: Phipps C. B. 
Published: May 2009

SUMMARYCore material from carbonate cemented sandstones of Eocene age from the Maracaibo Basin, Venezuela, exhibits evidence of post-burial sideritisation of calcite. the process being identical in its essentials with dolomitisation. and resulting in a marked increase in porosity and permeability of the cemented sandstones. As a result of this increase, sub-surface waters have been able to leach out much of the sideritc cement, and subsequent mechanical compaction of the sandstones has produced a characteristic “bead”-like arrangement of remnant sideritc granules around the sand grains. The whole process can be reconstructed from thin-sections, and these are used to illustrate the text.
The Geology of the Snøfjella and Dovrefjella in Vestspitsbergen
Authors: Preston John 
Published: May 2009

AbstractThe area yields marbles, schists, and quartzites, probably of Hecla Hoek age, a series similar in lithology to those in the Kongsfjorden region. Their structure and metamorphic condition fit in with the general picture of Caledonian trend and of increasing orogenic activity westwards. Later faulting along the western edge of a graben has broken this ground up into independent blocks as witnessed by the disposition of the Devonian conglomerates. The youngest rocks are a southerly outlier of the plateau basalts best seen around Woodfjorden, remnants of at least two flows are preserved, both of olivine basalt rich in olivine phenocrysts and carrying inclusions of a more alkaline rock type.
The Intrusion-Breccia of Dunmore, Co. Donegal
Authors: French W. J. , Pitcher W. S. 
Published: May 2009

AbstractA small plug-like body is made up of an intrusive breccia contained within a ring of felsite. The felsitic matrix of the breccia is of composite origin and certain textures may indicate contemporaneous breaking of crystals. Attention is drawn to the association of this diatreme with the suite of felsite, hornblende lamprophyre, and hornblendite intrusions clustered around the diapiric pluton of Ardara.
Partial silicification of chalk fossils from the Chilterns
Authors: Brown G. , Catt J. A. , Hollyer S. E. , Ollier C. D. 
Published: May 2009

SUMMARYThe calcite of brachiopod, lamellibranch and echinoid shells from the Upper and Middle Chalk of Hertfordshire and Bedfordshire is partly replaced by chalcedonic silica. The crystallographic forms of the silica are described, and its diagenetic emplacement inferred from thin section studies.
The Revised Ludlovian Stratigraphy of the Type Area—A Discussion
Authors: Phipps C. B. 
Published: May 2009

AbstractA recent revision of the type Ludlovian succession at Ludlow (Holland et al., 1959) has raised a number of problems concerning the classification and nomenclatureof the proposed divisions. It is here suggested that these can be resolved by adopting adual systemof classification, in which both rock-stratigraphic and biostratigraphic units are recognized. The impropriety of discarding the names Aymestry and Mocktree is established, and a plea is made for the erection of stages to aid in local and regional correlation.
Metamorphic Grade and Iron-Magnesium Distribution between Co-Existing Garnet-Biotite and Garnet-Hornblende
Authors: Frost M. J. 
Published: May 2009

AbstractIt is shown that in the two mineral pairs discussed the metamorphic grade can be estimated from the atomic ratios (Xa = Mg/Mg + Fe + 0·175 Mn + 0·360 Ca) in garnet and Xb = Mg/(Mg + Fe) in the other mineral. The standard error of the estimation is about one-third of the temperature range of the amphibolite facies.Where M is the metamorphic grade on an arbitrary scale, in which the lower boundary of the amphibolite facies is at 4·2 and the upper at 5·1, and K is the distribution coefficient (Xb—XaXb)/(Xa—XaXb), then the estimating equation is M = 5·6 — 1·5 log10 K.
On the Genus Amplexograptus Lapworth, Elles & Wood
Authors: Bulman O. M. B. 
Published: May 2009

AbstractThe type species of Amplexograptus is re-examined and is considered to include two distinct species. In neither of these is there any indication of a concavo-convex rhabdosome cross-section. A revised diagnosis of the genus is given and its relation to Climacograptus briefly discussed.
Steeply Plunging Recumbent Folds
Authors: Naha Kshitindramohan 
Published: May 2009

AbstractThe definition of a recumbent fold as one with subhorizontal axial surface is best with difficulties when recumbent folds plunge. Recumbent folds are redefined here as folds whose axial planes give subhorizontal trace in profile plane, with the fold-axis plunging at any angle up to 80°. A neutral to slightly antiformal recumbent fold half mile across and plunging 75° is described from the Pre-Cambrian metamorphic terrain in Eastern India.
The Upper Middle Hecla Hoek Rocks of Ny Friesland, Spitsbergen
Authors: Wilson C. B. 
Published: May 2009

AbstractThis paper gives a definitive description of the lithology and thicknesses of the Upper Middle Hecla Hoek rocks of Ny Friesland, Spitsbergen, arising out of Cambridge expeditions since 1951. The succession is the late Pre-Cambrian part of the Hecla Hoek Geosyncline, lying below the Tillite horizons and characterized essentially by limestones and dolomites.
A “Vein” of Trondhjemite aplite: Granitization of Quartzite forming the sole of a Fold-thrust, Malin Head, Co. Donegal
Authors: Reynolds Doris L. 
Published: May 2009

AbstractA narrow layer of quartzite, emplaced within epidiorite by foldthrusting, is transformed to albite-trondhjemite aplite and contiguous zones of the epidiorite are enriched in biotite. By reference to six chemical analyses it is found that, with but small additions of potash these transformations can be accounted for by the combined processes of (a) mechanical mixing of the initial quartzite and epidiorite, and (b) metamorphic inter-diffusion between this mixture and the adjoining epidiorite.
On the species Orbignyella fibrosa (Lonsdale)
Authors: Owen David E. 
Published: May 2009

AbstractThe species Alveolites fibrosa Lonsdale, 1839, described also as Stenopora fibrosa var. β Regularis McCoy, 1851, and referred to as Stenopora fibrosa var. incrustans McCoy, was recognized originally by Lonsdale (1839) as different from Calamopora fibrosa Goldfuss, 1826. It is described here as Orbignyella fibrosa (Lonsdale) and shown to occur typically in beds of Leintwardine age.
On Deformation at Thrust Planes in Shetland and the Jotunheim area of Norway
Authors: Flinn Derek 
Published: May 2009

AbstractIn both north-east Shetland and the Jotunheim area of Norway two nappes of crystalline rocks occur lying one above the other and separated in time and space by orogenic sediments. These sediments were formed in part at least by erosion of the lower, and first emplaced, of the two nappes in both areas. Later emplacement of the upper nappes caused the deformation and metamorphism of these rocks. In both Norway and Shetland large quartzite conglomerates which occur immediately beneath the upper nappes have been deformed on patterns which have been determined from a study of the pebble shapes. From these patterns in both areas it is argued that the deformation was due to flow caused by pressure differences developed in the sole of the advancing nappe and possibly to extrusion from beneath the nappe.
The Occurrence of Hypersthene in Hawaiian Basalts
Authors: Tilley C. E. 
Published: May 2009

AbstractThe occurrence of hypersthene in Hawaiian basalts, related broadly to the lime-silica values in the bulk analyses, is now considered and graphically expressed in terms of the quantitative proportions of the normative constituents, diopside, hypersthene, olivine, and quartz in analyses of Kilauea and Mauna Loa lavas.