bluuebunny/crossref_metadata_2025_split huggingface dataset:
Description in the geological sciences and the Lithostratigraphic Descriptive System, LSDØ2
Authors: Odell John 
Published: May 2009

SummaryA discussion of geological description and an account of the Descriptive System LSDØ2 are given. It is shown that by examination of the aims of description and of its main instrument, the geological observer, a set of principles and objectives may be established in order to design descriptive systems. The application of these principles is demonstrated by an account of the theory and practical aspects of the Lithostratigraphic Descriptive System LSDØ2.
A quantitative analysis of an Upper Westphalian fluviodeltaic succession and a comparison with earlier Westphalian deposits in the Kent Coalfield
Authors: Read W. A. 
Published: May 2009

SummaryThe Upper Westphalian succession in the National Coal Board's Eastling Wood Borehole, 1976 ‘TR 6303 1472’ has been analysed in terms of upward-fining and upward-coarsening semicycles, transition probabilities and entropies. This analysis confirms that the succession can be divided into a lower coal facies, which like the earlier Westphalian deposits of Kent was laid down dominantly in deltas but which includes numerous channel-fills, and an upper channel facies laid down in a more upstream fluvial environment.
Chloritoid-staurolite assemblages from Barrow's Zones in Central Perthshire, Scotland
Authors: Atherton M. P. , Smith R. A. 
Published: May 2009

SummaryChloritoid-biotite- and chloritoid-staurolite-bearing rocks occur around Blair Atholl, Perthshire. Textures suggest staurolite to be produced from chloritoid by a prograde ionic reaction involving muscovite. Chloritoid rocks are aluminous, lying above the muscovite-chlorite join, and staurolite formation involves the breakdown of chloritoid and muscovite. Their presence indicates that the chloritoid-biotite zone of Stonehaven continues as far SW as Central Perthshire, although its occurrence is severely limited by a lack of aluminium-rich rocks. The use of the chloritoid outcrop in the NE as an indication of pressure decrease to the SW is therefore queried.
The inadunate crinoid genus Cryphiocrinus Kirk
Authors: Strimple Harrell L. 
Published: May 2009

SummaryCryphiocrinus Kirk is a genus which may possess a delicate stem, or may lose the stem as an adult, making it essentially eleutherozoic. C. girtyi Kirk, type species, is documented with certainty from Chesterian rocks of Oklahoma and Arkansas for the first time. C. rotundus Kirk is reported from the Renault Formation of Illinois and a possible occurrence in the Pride Mountain Formation of Alabama is noted. The genus has previously been recognized in Chesterian, Upper Mississippian, (Lower Carboniferous), strata exposed in West Virginia, Kentucky and Oklahoma, U.S.A. Possible affinity with Hosieocrinus Wright from the Lower Limestone Group (Visean) in Scotland is discussed.
The Wolf Rock, Cornwall: new chemical, isotopic age and palaeomagnetic data
Authors: Harrison R. K. , Snelling N. J. , Merriman R. J. , Morgan G. E. , Goode A. J. J. 
Published: May 2009

SummaryBy systematic sampling (including the drilling of orientated cores) new data are presented on the chemistry, petrography, mineralogy, K/Ar isotopic age and remanent magnetism of the Wolf Rock, Cornwall. The overall homogeneity of the Rock is confirmed as a fine-grained fluxioned microporphyritic phonolite. Major joints strike NNW–SSE and NNE–SSW and there is a pronounced floor jointing. New whole-rock and probe analyses of the constituent minerals are given. Nosean, previously recorded, is found to be replaced by analcime, cancrinite and other minerals. K–Ar determinations on nepheline and K-feldspar give mean ages of 112±2, and 130±6 Ma respectively. The mean pole position of 70° N, 6° E, suggests that the 130 Ma pole for stable Europe may have been somewhat closer to Europe than previously supposed. The significance of this Lower Cretaceous magmatism in the context of Mesozoic volcanism in Southern England and European alkaline provinces is discussed.
The basic rock series in batholithic associations
Authors: Mullan H. S. , Bussell M. A. 
Published: May 2009

SummaryBasic rocks from the West Mexican Batholith and the Coastal Batholith of Peru are described. These are considered representative of the whole range of basic rocks in batholiths and their crystallization and subsequent history is related to the fluid pressure of the magma. Their role in batholithic evolution is discussed.
Origin of montmorillonite in the early Jurassic shales of NW Scotland
Authors: Amiri-Garroussi K. 
Published: May 2009

SummaryClay mineral analysis of shales in the early Liassic Lower Broadford Beds of the Hebrides reveals the presence of abundant quantities of montmorillonite whereas the Upper Broadford Beds contain illite, kaolinite and subordinate mixed layer minerals together with chlorite. Montmorillonite enrichment of the Lower Broadford Beds as a consequence of recent weathering contamination by doleritic sills can effectively be ruled out. It is argued that the montmorillonite may have been derived from the weathering of basic igneous rocks exposed in the sediment source area during Late Triassic times. By Upper Broadford Beds times, the igneous source was either eroded away or transgressed by the early Liassic sea.
K–Ar and Rb–Sr isotopic age studies on the Wolf Rock nosean phonolite, Cornwall
Authors: Mitchell J. G. , Macintyre R. M. , Pringle I. R. 
Published: May 2009

SummaryPotassium–argon and rubidium–strontium isotopic age studies of the Wolf Rock phonolite of SW England confirm its age as 131 Ma, with an initial87Sr/88Sr ratio of 0.703. The existence of a Mesozoic volcanic province of this age on the margin of the Labrador–Biscay rift is discussed with special reference to its implications for the early evolution of the N.Atlantic Ocean, and the general relationship of alkaline igneous activity to major periods of plate reorientation.
Rocks of unusual chemistry in the charnockitic terrains of India, and their geological significance
Authors: Viswanathan S. 
Published: May 2009

SummaryThe paper reports the occurrence in the 2.9–3.1 B.Y. old charnockitic terrains of Southern India of some basic charnockites that are strikingly similar, chemically, to basaltic komatiite from the 3.4 B.Y. old Barberton greenstone belt of Southern Africa, and suggests that the pre-metamorphic evolution of Archaean charnockitic terrains followed the same trends that characterized the development of Archaean greenstone belts. The main events in the evolution of one such terrain, the ‘Madras granulite belt’, before it was subjected to granulite facies meamorphism some 2.6 B.Y. ago, is outlined in Table 2.
Tectonic control on the formation of some fibrous quartz veins, Mid-Wales
Authors: Garth Raybould J. 
Published: May 2009

SummaryProtoquartzites outcropping in a small anticline in the Plynlimon area of mid-Wales contain numerous flat-lying and low-angle, fibrous quartz veins, which are subparallel to the ab plane of the fold. The quartz crystals are elongated at a high angle to the vein walls, and in some cases exhibit a curvature which is thought to have been adopted as the crystals grew. The orientation and internal structure of the veins suggest that they formed on fractures initiated during compression and extended by hydraulic fracture, the crystal curvature being a result of shearing during syntectonic crystal growth. Pore water was important both in bringing about the critical effective stresses required for fracturing and as a carrier of locally remobilized free silica.
A Cretaceous laterite in the Negev Desert, southern Israel
Authors: Singer A. 
Published: May 2009

SummaryKaolinite is the major mineral in the saprolite of a fossil laterite, found intercalated amid basalt flows from the Lower Cretaceous in the Negev desert. The kaolinite was produced by pseudomorphic alteration of plagioclase. Haematite is a secondary product and accumulated in a ferruginous soil horizon. In the saprolite Sr, Mn and Cu were strongly depleted, Zn and Ni were slightly depleted, whereas Co and Cr accumulated. In the ferruginous horizon, Sr, Mn, Cu and Zn were severely depleted, while Cr and Ni accumulated. The lateritic formation is evidence for the possible existence of tropical or intertropical conditions during the Lower Cretaceous in the Negev.
Textural patterns at porphyroblast margins and their use in determining the time relations of deformation and crystallization
Authors: Ferguson C. C. , Harte B. 
Published: May 2009

SummaryTextural patterns characteristic of supposed pre-, post- and to a lesser extent syn-tectonic porphyroblasts are reviewed. Difficulties of interpretation arise where anSi(internal schistosity) is absent, andSe(external schistosity) behaviour adjacent to porphyroblast margins is the only available criterion; examples may be found showing truncation ofSeby pre-Seporphyroblasts. Truncation and/or deflection textures are not by themselves sufficient criteria for determining the time relations of particular phases of deformation and crystallization.
Protosuchus, Proterochampsa, and the origin of phytosaurs and crocodiles
Authors: Walker A. D. 
Published: May 2009

SUMMARYStudy of casts ofStegomosuchus, a small reptile from the Upper Trias of the Connecticut Valley, hitherto regarded as a pseudosuchian thecodont, suggests that the skull ofProtosuchusincludes two pairs of supraorbital bones, and as a consequence the narrow interorbital region indicates a closer relationship to the South African genusNotochampsathan has previously been thought. These three genera of late Triassic crocodilians are placed in the family Stegomosuchidae von Huene, 1922.Proterochampsa,from the Ischigualasto Formation of Argentina, described by Reig (1959) and Sill (1967) as an ancestral crocodile, is considered to be an extremely primitive phytosaur.
The stratigraphy of a geosynclinal succession in western Sierra Leone, West Africa
Authors: Allen P. M. 
Published: May 2009

SUMMARYThe Rokel River Series of Sierra Leone is re-defined, and subdivided into the Rokel River Group and the Taban Formation. The Rokel River Group consists of six formations which represent the development and infilling of an eugeosyncline, and has been mildly metamorphosed and folded at least three times. The Taban Formation contains fluvial sediments deposited after orogenesis.
Drumlin measurements: a test of the reliability of data derived from 1:25000 scale topographic maps
Authors: Rose J. , Letzer J. M. 
Published: May 2009

SummaryMeasurements have been made on drumlins from the Glasgow district and eastern Westmorland, using 1:25000 topographic maps and direct field mapping. Comparison of the results suggests that topographic maps provide data which varies in accuracy with the clarity of the drumlin pattern depicted by the map, and the character of the particular descriptive parameter. Dimensionless parameters such as elongation ratio, tapering value (k), and stoss-point ratio are most accurately estimated, but size, spacing and density are consistently inaccurate, and the number of drumlins recognized is, at best, only 50 % of the number of drumlins that exist in the field. It is suggested that topographic maps fail to give information at the precision level required for the analysis of this type of glacier bedform.
The stratigraphy of Barbuda, West Indies
Authors: Brasier M. D. , Mather J. D. 
Published: May 2009

SummaryThe geology of Barbuda, a low-lying island in the Lesser Antilles, is reexamined and the stratigraphy is revised. The oldest rocks are limestones of the Highlands Formation, a Middle Miocene accumulation of fore-reef facies. This is overlain successively by the Pleistocene Beazer and Codrington Formations, limestone accumulations of reefal, lagoonal and dune facies. The Holocene Palmetto Point Formation is comprised of extensive beach ridge and dune limestones. From this, the Barbuda Bank (which includes Antigua) is considered to have had a geological history like the neighbouring Anguilla and Guadeloupe Banks.
The morphology and systematics of ‘Didymograptus’ spinosus Ruedemann, 1904, and allied species from the Lower Ordovician
Authors: Archer J. B. , Skevington D. 
Published: May 2009

SummaryThe first European occurrence of ‘Didymograptus’ spinosus Ruedemann, 1904, is reported. A re-description of this species is provided, based on the lectotype and new material from the West of Ireland. ‘D.’ spinosus is shown to possess the essential characteristics of the genus Holmograptus Koztowski, 1954, to which it is accordingly referred.Didymograptus nodosus Harris, 1926, and Tylograptus regularis Mu, 1957, together with certain other species of Tylograptus described by Mu (1957), are junior synonyms of Holmograptus spinosus. Holmograptus Kozlowski, 1954, is a senior synonym of Tylograptus Mu, 1957.
The greenschist facies assemblages of the lower Kumaon Himalaya
Authors: Das B. K. 
Published: May 2009

SummaryThe mineral assemblages of the pelitic rocks of the chlorite and biotite zones of the Kumaon Himalaya are characteristic of the quartz–albite–muscovite–cnlorite and quartz–albite–epidote–biotite sub-facies of the greenschist facies. The appearance of garnet in the sericite–chlorite pelites is due to bulk composition which plots above the muscovite–chlorite join in the AKF diagram. The variation in composition of coexisting sericite and chlorite is related to bulk composition of the rock.
An Upper Mesozoic island-arc–back-arc system in the southern Andes and South Georgia
Authors: Suárez M. , Pettigrew T. H. 
Published: May 2009

SummaryThe Upper Jurassic–Lower Cretaceous strato-tectonic belts of the southern Andes and South Georgia, 2000 km apart, can be correlated and explained as the products of an island-arc–back-arc system. From the Pacific Ocean to the Atlantic, these belts, which exhibit structural and metamorphic differences, are: (1) a pyroclastic belt developed on an ensialic volcanic arc; (2) a back-arc flysch sequence underlain in the southern Andes by a basic complex with oceanic affinities; this was intruded into continental crust as a result of sea-floor spreading which created a marginal basin; (3) a slate sequence deposited on a continental shelf. The pyroclastic and marginal basin belts and the adjacent part of the continental shelf were folded and uplifted during the early Upper Cretaceous, whereas the foreland part of the continental shelf assemblage underwent deformation during the early Tertiary.
Rock composition, density and a variation diagram
Authors: French W. J. 
Published: May 2009

SummaryThe relationship between silicate rock density and composition has been investigated and empirical formulae have been obtained that give a factor equivalent to a ‘normative’ density. Comparison between this factor and measured density may provide useful diagrams assisting the interpretation of metamorphic petrogenesis. The factor itself is a viable differentiation index aiding comparison between the compositions and liquidus temperatures of volcanic suites.
The significance of the melting interval of basaltic magmas at various pressures
Authors: Maaløe S. 
Published: May 2009

SummaryThe melting intervals of basaltic magmas are investigated in detail at various pressures, as the size of the interval has an important bearing on the genesis of igneous rocks. Tholeiitic magmas do not have a more pronounced four phase proximity at low pressures than at higher ones. This result seems to oppose the generally accepted low pressure character of these magmas; but as there is a general decrease in melting intervals with increasing pressure, the four phase proximity is nevertheless sustained. The melting intervals of alkaline rocks decrease rapidly with increasing pressure. Small variations in the temperature may therefore generate large variations in the composition of the liquids developed at high pressures.
The Garnedd-wen Formation (Ashgillian) of the Towyn-Abergynolwyn district, Merionethshire
Authors: James D. M. D. 
Published: May 2009

SummaryA lithostratigraphy is described and related to that in the adjacent Corris-Machynlleth district. Thickness of the Formation is estimated to be c. 500 m near Towyn rather than c. 1000 m as generally accepted, although poor exposure precludes accurate determination. Palaeocurrent data are given for a prominent interval of turbidite arenites, here termed the Llyn Barfog Member. Sedimentary facies are interpreted as slope-base and deep basinal deposits and are consistent with control of sedimentation by the Bala and Corris ‘basement faults’.
Aschemonella longicaudata sp. nov. from the Permian of Derbyshire, England
Authors: Anderson F. W. 
Published: May 2009

AbstractA foraminiferal fauna in the Lower Permian Marls of the Lowpit Lane Borehole, Derbyshire, included numerous examples of a new species of the genus Aschemonella Brady. This is described as Aschemonella longicaudata sp. nov. and the possible growth form of the genus is discussed.
Differential Retrogressive Metamorphism in Granulites of the Karasuk Group, Karamoja, Uganda
Authors: Clark Lewis 
Published: May 2009

AbstractThe Karasuk Group comprises a series of meta-sedimentary rocks of the amphibolite facies with localized areas of granulites. The granulites have been subjected to retrogressive metamorphism, and acid granulites are much more retrograded than associated basic granulites. It is suggested that this differential retrogression of the granulites is related to differing susceptibilities of the two types to the penetrative deformation to which they have been subjected.
Tholeiite and Tholeiitic Series
Authors: Tilley C. E. , Muir I. D. 
Published: May 2009

AbstractThe restrictions proposed by Jung (1958) on the definition and use of the term tholeiite, and the more recent drastic proposal for its abandonment (Chayes, 1966) are considered. Both proposals are rejected and re-emphasis given in support of the broad use of the term both as a rock and magma type, and as a progenitor of an igneous rock series.
Sections in the Beach-plain Deposits of Dungeness, Kent
Authors: Hey R. W. 
Published: May 2009

AbstractRecent excavations on Dungeness have provided excellent sections through the deposits of its late Holocene beach-plains. The material at the surface is loose shingle, but at a depth of a few feet this passes down into gravel packed with sand. The gravel in turn rests upon almost stoneless sand with marine shells, the contact between the two deposits falling from - 13 feet O.D. in the most northerly section to - 24 feet in the most southerly.It is confirmed that the more pebbly deposits were laid down on an actively prograding foreshore, as has generally been supposed. Problems are raised, however, by the low levels of their base and by some of their structural and lithological features. These are discussed, and explanations are offered where possible.
Sedimentary Infillings of Fossils and Cavities in Limestone at Treak Cliff, Derbyshire
Authors: Broadhurst F. M. , Simpson I. M. 
Published: May 2009

ABSTRACTObservations of partial and complete sedimentary infillings of fossils and rock cavities at two localities on Treak Cliff, Castleton, Derbyshire, lead to the conclusion that at these localities the present dip of the limestones is largely or entirely depositional in origin. This conclusion agrees, more or less, with claims made in previous publications but, so far as the authors are aware, this is the first time that direct evidence of high initial dips at Treak Cliff has been recorded.
Order of Abundant Crystal Nucleation in a Natural Magma
Authors: Hawkes D. D. 
Published: May 2009

ABSTRACTRhythmic layering in the Freetown Complex and in some other layered intrusions may be due to the different powers of nucleation of the primary minerals from an undercooled magma. It is suggested that, in slowly cooled intrusions, the total number of crystals per cm3 in a rock (whole rock index) is a measure of the amount of undercooling; rocks with a low whole rock index crystallized at or near the equilibrium temperature while rocks with a high index crystallized under conditions of undercooling. If this is so, then it is possible to determine the order of abundant nucleation of the primary minerals by graphical means. Only a slight amount of undercooling, perhaps of the order of 4 or 5° C, is necessary to produce marked changes in the order of separation of the minerals from the magma.
The Jurassic and Cretaceous Sequence in Spitsbergen
Authors: Parker J. R. 
Published: May 2009

ABSTRACTThe Jurassic and Cretaceous sequence of Spitsbergen, Svalbard archipelago, is described and a revised lithostratigraphical scheme, of four formations, is proposed. The main episode of tectonic activity, together with dolerite intrusion, was in late Jurassic-early Cretaceous times and is represented by a non-sequence and local unconformity between the two lower formations. The faunal succession is also discussed.
Notes on the Structure of the Ben Lawers Synform
Authors: Treagus J. E. 
Published: May 2009

AbstractA detailed examination of some new exposures in the Ben Lawers range reveals folds of three deformational episodes. These are described megascopically and microscopically. The foldgeometry is complex but the kinematic axes of each deformation are shown to be closely related. The folds of the first deformation have relationships which confirm the position of these rocks on the inverted limb of the Tay Nappe. Folds with relationships shown by those of the second deformation have not been described from adjacent areas. The folds of the third deformation are associated with the formation of the Ben Lawers Synform
The Origin of the “Beach-Beds” in the Lower Carboniferous of Castleton, Derbyshire
Authors: Sadler Helen E. 
Published: May 2009

AbstractThe “Beach-Beds” at Castleton, Derbyshire, are shown to be detrital deposits containing numerous water-worn and broken brachiopod shell fragments set in a matrix of finely comminuted shell and crinoid debris. They occur at the junction of the fore-reef and basin facies of the Carboniferous Limestone. Previous interpretations of the “Beach-Beds” as cliff-foot screes or as beds lying above an unconformity are not supported, and it would appear that they are composed largely of debris transported down a submarine channel (the approximate position of which is now the dry valley of the Winnats) rather than in shallow water on a sea-beach, being deposited at the foot of the channel contemporaneously with the adjacent fore-reef beds.
The Pre–Cambrian–Palaeozoic Boundary of the Malverns
Authors: Phipps C. B. , Reeve F. A. E. 
Published: May 2009

AbstractThe nature of the contact between Pre–Cambrian and Palaeozoic rocks on the western flanks of the Malvern Hills is discussed. Evidence from the regional geological setting and from the contact exposed in Gullet Quarry is only consistent with a faulted junction. Interpretations by Butcher (1962), Reading and Poole (1961) cannot be supported in the field and it is proposed to revert to Groom's (1899) interpretation of the western margin of the Pre–Cambrian as the outcrop of a major fault.
Conditions in the Metamorphic Caledonides during the Period of Late-orogenic Cooling
Authors: Watson Janet 
Published: May 2009

AbstractThe paper deals with regional variations in the contact–effects of Caledonian granites and in the characters of certain associated minor intrusions in the metamorphic Caledonides. It is suggested that these variations are related to the thermal structure of the fold–belt at the time of emplacement.