bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of 280 000 cases in Dutch midwifery practices: a descriptive study
Authors: Amelink‐Verburg MP , Verloove‐Vanhorick SP , Hakkenberg RMA , Veldhuijzen IME , Bennebroek Gravenhorst J , Buitendijk SE
Published: December 2007

Objective  To assess the nature and outcome of intrapartum referrals from primary to secondary care within the Dutch obstetric system.

Design  Descriptive study.

Setting  Dutch midwifery database (LVR1), covering 95% of all midwifery care and 80% of all Dutch pregnancies (2001–03).

Population  Low‐risk women (280 097) under exclusive care of a primary level midwife at the start of labour either with intention to deliver at home or with a personal preference to deliver in hospital under care of a primary level midwife.

Methods  Women were classified into three categories (no referral, urgent referral and referral without urgency) and were related to maternal characteristics and to neonatal outcomes.

Main outcome measures  Distribution of referral categories, main reasons for urgent referral, Apgar score at 5 minutes, perinatal death within 24 hours and referral to a paediatrician within 24 hours.

Results  In our study, 68.1% of the women completed childbirth under exclusive care of a midwife, 3.6% were referred on an urgency basis and 28.3% were referred without urgency. Of all referrals, 11.2% were on an urgency basis. The main reasons for urgent referrals were fetal distress and postpartum haemorrhage. The nonurgent referrals predominantly took place during the first stage of labour (73.6% of all referrals). Women who had planned a home delivery were referred less frequently than women who had planned a hospital delivery: 29.3 and 37.2%, respectively (P < 0.001).On average, the mean Apgar score at 5 minutes was high (9.72%) and the peripartum neonatal mortality was low (0.05%) in the total study group. No maternal deaths occurred. Adverse neonatal outcomes occurred most frequently in the urgent referral group, followed by the group of referrals without urgency and the nonreferred group.

Conclusions  Risk selection is a crucial element of the Dutch obstetric system and continues into the postpartum period. The system results in a relatively small percentage of intrapartum urgent referrals and in overall satisfactory neonatal outcomes in deliveries led by primary level midwives.
A Spectral Method for Describing the Response of a Parametrically Excited System Under External Random Excitation
Authors: Bachelet L. , Driot N. , Perret-Liaudet J.
Published: December 2007

This paper describes an original approach for computing the stationary response of linear periodic time variant MDOF systems subjected to stationary stochastic external excitation. The proposed method is derived in the frequency domain, is purely numerical, and provides the explicit power spectral density (PSD) of the response. Its implementation first requires expressing the PSD response as a function of the bilinear Fourier transform of the so-called bitemporal impulse response. Then, the spectral method is used to compute the bispectrum function. The efficiency of this spectral process is demonstrated by comparison with Monte Carlo simulations on three parametrical systems. The computational time required and the accuracy are very satisfactory.
Immunity to a Self-Derived, Channel-Forming Peptide in the Respiratory Tract
Authors: van Ginkel Frederik W. , Iwamoto Takeo , Schultz Bruce D. , Tomich John M.
Published: December 2007

The channel-forming peptide NC-1130 was generated based on the amino acid sequence of the M2 segment of the spinal cord α-subunit of the glycine receptor and has been proposed as a therapeutic agent for anion channelopathies such as cystic fibrosis. Lysine adduction and amino acid substitutions at positions T19R and S22W of the peptide improved its performance as an ion channel. However, these modifications generated an altered self, potentially making this NC-1130 peptide immunogenic, which could preclude the repeated use of NC-1130 as a therapeutic agent. To measure the ability of NC-1130 to induce an immune response, it was administered nasally with or without cholera toxin (CT). The NC-1130 peptide, when given alone without adjuvant, induced very little peptide-specific immunity based on analyses of peptide-specific antibodies by enzyme-linked immunosorbent assay and enzyme-linked immunospot assay, induction of cytokine production, and delayed-type hypersensitivity (DTH) responses. The administration of NC-1130 with the mucosal adjuvant CT induced peptide-specific immunoglobulin G (IgG) antibodies and DTH responses and a Th2-dominant cytokine response. The coadministration of the strong mucosal adjuvant CT induced a systemic NC-1130-specific IgG response but not a mucosal peptide-specific antibody response. The lack of peptide-specific immunity and specifically mucosal immunity should allow repeated NC-1130 peptide applications to epithelial surfaces to correct anion channelopathies.
Dual-Reporter Phenotypic Assay for Human Immunodeficiency Viruses
Authors: Kajiwara Keiko , Kodama Eiichi , Sakagami Yasuko , Naito Takeshi , Matsuoka Masao
Published: December 2007

We have established a novel human immunodeficiency virus (HIV) tandem-reporter assay using HIV receptor-transduced NP-2 cells with long terminal repeat-controlled β-galactosidase, inserted internal ribosome entry site, and secretary alkaline phosphatase genes. This assay allows users to detect replication of clinical isolates, indicating its useful application as an HIV phenotypic assay.
Development of PCR Assays with Nested Primers Specific for Differential Detection of Three Human Anelloviruses and Early Acquisition of Dual or Triple Infection during Infancy
Authors: Ninomiya Masashi , Takahashi Masaharu , Nishizawa Tsutomu , Shimosegawa Tooru , Okamoto Hiroaki
Published: December 2007

We recently identified a novel human virus classifiable into a third group in the genus
Anellovirus
, tentatively designated torque teno midi virus (TTMDV), with a circular DNA genome of 3.2 kb and genomic organization resembling those of torque teno virus (TTV) (3.8 to 3.9 kb) and torque teno mini virus (TTMV) (2.8 to 2.9 kb). TTMDV was characterized by extreme genetic diversity similar to the TTV and TTMV genomes. Taking advantage of universal and virus species-specific primers derived from a highly conserved area located just downstream of the TATA box of the TTV, TTMDV, and TTMV genomes, a PCR method with simultaneous amplification of the genomic DNAs of these three anelloviruses in the first round and subsequent differential amplifications of these viruses in the second round was developed. High prevalence of TTMDV viremia was seen in adults (75/100 [75%]), comparable with the prevalences of TTV viremia (100%) and TTMV viremia (82%). Although none of 10 cord blood samples had detectable TTV, TTMDV, and TTMV DNAs, the prevalences of these three anelloviruses increased with the number of months after birth of the individual and reached 100% for individuals at one year of age. Dual or triple infection of TTV, TTMDV, and/or TTMV was seen in 10 (47.6%) of 21 infants 9 to 180 days of age and more frequently among infants 181 to 364 days of age (20/23 [86.9%]), comparable with the 93.1% (243/261) prevalence among subjects 1 to 81 years of age, indicating early acquisition of dual or triple anellovirus infection during infancy.
CCR5Δ3259537-G/A Promoter Polymorphism Is Associated with Low Translational Efficiency and the Loss ofCCR5Δ32Protective Effects
Authors: Jin Qingwen , Agrawal Lokesh , Meyer L. , Tubiana R. , Theodorou Ioannis , Alkhatib Ghalib
Published: December 2007

We have recently demonstrated that the CCR5Δ32 protein interacts with CCR5 and CXCR4 and down-modulates their cell surface expression. We have also reported the absence of detectable expression of the truncated CCR5Δ32 protein in four out of six human immunodeficiency virus-infected (HIV+)CCR5−/−individuals. To explain the defect in protein expression in these samples, we cloned and sequenced the promoter regions of the six HIV+individuals. We have identified several polymorphisms in theCCR5Δ32promoter region, but these polymorphisms were not associated with significant differences in mRNA levels. Coupled in vitro transcription/translation and polyribosome analysis demonstrated a strong association between a variant genotype designatedCCR5Δ3259537-A/A and a low translation efficiency. Protein analysis indicated that the peripheral blood mononuclear cells from two of the HIV+CCR5−/−individuals carrying theCCR5Δ3259537-A/A variant expressed trace amounts of CCR5Δ32 protein compared to the individuals carrying theCCR5Δ3259537-G/G genotype. The results imply that the absence of CCR5Δ32 protein in two HIV+individuals is due to a genetic defect in the translation of the protein. Together, these results highlight the importance of the CCR5Δ32 protein as an HIV suppressive factor and provide further insight into the mechanism of the protective effect of theCCR5Δ32mutation.
Probing the Structural States of Human Immunodeficiency Virus Type 1 Pr55

gag

by Using Monoclonal Antibodies
Authors: LeBlanc Jason J. , Perez Omar , Hope Thomas J.
Published: December 2007

Gag-FP (fluorescent protein) fusion constructs are commonly used to study human immunodeficiency virus type 1 assembly, yielding diffuse signals throughout the cytoplasm along with punctate signals routinely described as virus-like particles (VLPs) representing assembled but unprocessed Gag. However, these particles cannot be accurately described as VLPs, since fluorescence microscopy cannot provide structural resolution. We demonstrate here that the inability of a monoclonal p24 antibody to bind its cognate epitope when unprocessed Gag is assembled distinguishes VLPs from unassembled, monomeric Gag. Furthermore, we show that assembled and unassembled Gag punctate signals travel along microtubules. These monoclonal antibody studies provide a new tool for examining retroviral assembly.
Antibody-Dependent Enhancement of Hepatitis C Virus Infection
Authors: Meyer Keith , Ait-Goughoulte Malika , Keck Zhen-Yong , Foung Steven , Ray Ranjit
Published: December 2007

Hepatitis C virus (HCV) often causes a persistent infection associated with hypergammaglobulinemia, high levels of antiviral antibody and circulating immune complexes, and immune complex disease. We previously reported that only a limited neutralizing activity to vesicular stomatitis virus or HCV pseudotype is generated in animals immunized with recombinant HCV envelope proteins and chronically infected HCV patient sera. Interestingly, when some of these neutralizing sera were diluted into a range of concentrations below those that reduced virus plaque number, an increase in pseudotype plaque formation was observed. Purified HCV E2-specific human monoclonal antibodies were used to further verify the specificity of this enhancement, and one- to twofold increases were apparent on permissive Huh-7 cells. The enhancement of HCV pseudotype titer could be inhibited by the addition of a Fc-specific anti-human immunoglobulin G Fab fragment to the virus-antibody mixture prior to infection. Treatment of cells with antibody to Fc receptor I (FcRI) or FcRII, but not FcRIII, also led to an inhibition of pseudotype titer enhancement in an additive manner. Human lymphoblastoid cell line (Raji), a poor host for HCV pseudotype infection, exhibited a four- to sixfold enhancement of pseudotype-mediated cell death upon incubation with antibody at nonneutralizing concentrations. A similar enhancement of cell culture-grown HCV infectivity by a human monoclonal antibody was also observed. Taken together, antibodies to viral epitopes enhancing HCV infection need to be taken into consideration for pathogenesis and in the development of an effective vaccine.
Conserved Leucines in N-Terminal Heptad Repeat HR1 of Envelope Fusion Protein F of Group II Nucleopolyhedroviruses Are Important for Correct Processing and Essential for Fusogenicity
Authors: Long Gang , Pan Xiaoyu , Vlak Just M.
Published: December 2007

The heptad repeat (HR), a conserved structural motif of class I viral fusion proteins, is responsible for the formation of a six-helix bundle structure during the envelope fusion process. The insect baculovirus F protein is a newly found budded virus envelope fusion protein which possesses common features to class I fusion proteins, such as proteolytic cleavage and the presence of an N-terminal open fusion peptide and multiple HR domains on the transmembrane subunit F
1
. Similar to many vertebrate viral fusion proteins, a conserved leucine zipper motif is predicted in this HR region proximal to the fusion peptide in baculovirus F proteins. To facilitate our understanding of the functional role of this leucine zipper-like HR1 domain in baculovirus F protein synthesis, processing, and viral infectivity, key leucine residues (Leu209, Leu216, and Leu223) were replaced by alanine (A) or arginine (R), respectively. By using
Autographa californica
multicapsid nucleopolyhedrovirus (AcMNPV) as a pseudotype expression system, we demonstrated that all mutant F proteins incorporated into budded virus, indicating that leucine substitutions did not affect intercellular trafficking of F. Furin-like protease cleavage was not affected by any of the leucine substitutions; however, the disulfide bridging and N-linked glycosylation patterns were partly altered. Single substitutions in HR1 showed that the three leucine residues were critical for F fusogenicity and the rescue of AcMNPV infectivity. Our results support the view that the leucine zipper-like HR1 domain is important to safeguard the proper folding, glycosylation, and fusogenicity of baculovirus F proteins.
Relative Influence of the Adeno-Associated Virus (AAV) Type 2 p5 Element for Recombinant AAV Vector Site-Specific Integration
Authors: Guilbaud Mickaël , Chadeuf Gilliane , Avolio Fabio , François Achille , Moullier Philippe , Recchia Alessandra , Salvetti Anna
Published: December 2007

The p5 promoter region of the adeno-associated virus type 2 (AAV-2)
rep
gene has been described as essential for Rep-mediated site-specific integration (RMSSI) of plasmid sequences in human chromosome 19. We report here that insertion of a full-length or minimal p5 element between the viral inverted terminal repeats does not significantly increase RMSSI of a recombinant AAV (rAAV) vector after infection of growth-arrested or proliferating human cells. This result suggests that the p5 element may not improve RMSSI of rAAV vectors in vivo.
The Spike Protein of Infectious Bronchitis Virus Is Retained Intracellularly by a Tyrosine Motif
Authors: Winter Christine , Schwegmann-Wessels Christel , Neumann Ulrich , Herrler Georg
Published: December 2007

We have analyzed the intracellular transport of the spike (S) protein of infectious bronchitis virus (IBV), an avian coronavirus. Surface expression was analyzed by immunofluorescence microscopy, by surface biotinylation, and by syncytium formation by S-expressing cells. By applying these methods, the S protein was found to be retained intracellularly. Tyr1143 in the cytoplasmic tail was shown to be a crucial component of the retention signal. Deletion of a dilysine motif that has previously been suggested to function as a retrieval signal did not abolish intracellular retention. Treatment of the S proteins with endoglycosidases did not reveal any differences between the parental and the mutant proteins. Furthermore, all S proteins analyzed were posttranslationally cleaved into the subunits S1 and S2. In coexpression experiments, the S protein was found to colocalize with a Golgi marker. Taken together, these results indicate that the S protein of IBV is retained at a late Golgi compartment. Therefore, this viral surface protein differs from the S proteins of transmissible gastroenteritis virus and severe acute respiratory syndrome coronavirus, which are retained at a pre-Golgi compartment or transported to the cell surface, respectively. The implications of these differences are discussed.
Direct Correlation between Sialic Acid Binding and Infection of Cells by Two Human Polyomaviruses (JC Virus and BK Virus)
Authors: Dugan Aisling S. , Gasparovic Megan L. , Atwood Walter J.
Published: December 2007

For the human polyomaviruses JC virus (JCV) and BK virus (BKV), the first step to a successful infection involves binding to sialic acid moieties located on the surfaces of host cells. By stripping and then reconstituting specific sialic acid linkages on host cells, we show that JCV uses both α(2,3)-linked and α(2,6)-linked sialic acids on N-linked glycoproteins to infect cells. For both JCV and BKV, the sialic acid linkages required for cell surface binding directly correlate with the linkages required for infection. In addition to sialic acid linkage data, these data suggest that the third sugar from the carbohydrate chain terminus is important for virus binding and infection.
Highly Conserved Regions of Influenza A Virus Polymerase Gene Segments Are Critical for Efficient Viral RNA Packaging
Authors: Marsh Glenn A. , Rabadán Raúl , Levine Arnold J. , Palese Peter
Published: December 2007

The genome of the influenza A virus is composed of eight different segments of negative-sense RNA. These eight segments are incorporated into budding virions in an equimolar ratio through a mechanism that is not fully understood. Two different models have been proposed for packaging the viral ribonucleoproteins into newly assembling virus particles: the random-incorporation model and the selective-incorporation model. In the last few years, increasing evidence from many different laboratories that supports the selective-incorporation model has been accumulated. In particular, different groups have shown that some large viral RNA regions within the coding sequences at both the 5′ and 3′ ends of almost every segment are sufficient for packaging foreign RNA sequences. If the packaging regions are crucial for the viability of the virus, we would expect them to be conserved. Using large-scale analysis of influenza A virus sequences, we developed a method of identifying conserved RNA regions whose conservation cannot be explained by population structure or amino acid conservation. Interestingly, the conserved sequences are located within the regions identified as important for efficient packaging. By utilizing influenza virus reverse genetics, we have rescued mutant viruses containing synonymous mutations within these highly conserved regions. Packaging of viral RNAs in these viruses was analyzed by reverse transcription using a universal primer and quantitative PCR for individual segments. Employing this approach, we have identified regions in the polymerase gene segments that, if mutated, result in reductions of more than 90% in the packaging of that particular polymerase viral RNA. Reductions in the level of packaging of a polymerase viral RNA frequently resulted in reductions of other viral RNAs as well, and the results form a pattern of hierarchy of segment interactions. This work provides further evidence for a selective packaging mechanism for influenza A viruses, demonstrating that these highly conserved regions are important for efficient packaging.
Two Plinian-type eruptions in the Azores
Authors: WALKER GEORGE PATRICK LEONARD , CROASDALE RONALD
Published: December 2007

The Agua de Pau volcano on the island of Sã o Miguel is blanketed with many trachytic pumice deposits, two of which have been selected for detailed study. One, resulting from an eruption 4600 years B.P., has a volume of 0.6–0.7 km
3
(dense rock equivalent) and is mostly a coarse-grained homogeneous pumice breccia produced by a continuous gas blast plinian eruption of great vigour. Pyroclastic flow deposits form fine-grained beds in this deposit, and diagnostic criteria are proposed for them. Such beds, forming thin layers interstratified with a coarser-grained deposit, are easily misinter-preted as air-fall ashes. The other deposit, that of
a.d
. 1563, has about one-quarter the volume and is well bedded partly resulting from fluctuations in vigour of the eruption and partly from rain-showers. Field grain-size measurements, and mechanical analyses of 100 samples from the two deposits, have been made to learn the value of such measurements and to understand the factors which influence the grain-size parameters. The Fogo A deposit shows striking variations in the proportions of pumice, crystals and lithic fragments. From simple field measurements it seems possible to determine
inter alia
the threshold diameter between ballistic fragments and fragments which have settled from the ash cloud.
A correlation of Silurian rocks in the British Isles
Authors: COCKS LEONARD ROBERT MORRISON , HOLLAND CHARLES HEPWORTH , RICKARDS RICHARD BARRIE , STRACHAN ISLES
Published: December 2007

A discussion of Silurian stratigraphical classification is followed by detailed comments upon the correlation of Llandovery, Wenlock, Ludlow, and post-Ludlow pre-Gedinnian rocks throughout the British Isles. A main correlation chart shows selected successions in Wales and the Welsh Borderland, North-West England, and Scotland. Subsidiary charts relate respectively to the Silurian inliers south-east of the main Welsh outcrops and to those of the Midland Valley of Scotland. A separate chart is provided for all the Irish Silurian. The concealed Silurian rocks of Eastern and Southern England are considered relatively briefly, as are the enigmatic records from Cornwall. Finally a chart and short commentary serve to correlate the Silurian successions of Bohemia, Thuringia, Podolia, Estonia and Gotland with the standard employed here for the British Isles. There is an extensive bibliography.
Some Namurian (E
2
) paralic sediments in Central Scotland: an investigation of depositional environment and facies changes using iterative-fit trend-surface analysis
Authors: READ WILLIAM ALFRED , DEAN JOHN MICHAEL , COLE ALFRED JOHN
Published: December 2007

The effectiveness of trend-surface analysis when applied to geological problems has been greatly increased by the use of iterative-fit trend surfaces, in addition to conventional overall-fit surfaces, because the former surfaces generally satisfy a considerably higher proportion of the total variation than the latter, yet remain completely objective. Such trend surfaces have been used, together with conventional stratigraphical and sedimentological methods, in an analysis of the unusually thick and laterally-persistent cycle which lies between the Upper Hirst and Plean No. 1 coals and includes the Calmy Limestone. In the differentially-subsiding Kincardine Basin thin, laterally-impersistent coals and seatearths split the upper part of the cycle into a series of thinner cycles.

The regional sedimentation patterns of most of the variables studied are related to the pattern of total thickness of strata and hence to net subsidence. An exception is the Upper Hirst Coal which thickens fairly regularly eastwards. The sediments resemble those in modern deltas and reflect an initial widespread marine transgression followed by the readvance of deltas. A whole series of minor deltalobes or crevasse systems progressively filled up the basin until, in Plean No. 1 Coal times, coalswamp vegetation recolonized almost the entire area.
The structure of the Gulf of Suez (Clysmic) rift, with special reference to the eastern side
Authors: ROBSON DOUGLAS ARTHUR
Published: December 2007

The stratigraphical sequence includes Palaeozoic (resting unconformably upon a Pre-Cambrian peneplane), Mesozoic and Tertiary rocks. These were deposited uniformly over the entire region although in Egypt the succession thins towards the south. Miocene rocks rest unconformably on earlier strata with which they contrast sharply in showing remarkable facies changes closely related to structural movements. Igneous activity was on a subdued scale and confined to Oligocene times. Dykes generally run parallel to the main Clysmic rift trend.

Rift faulting was initiated in Oligocene and continued into post-Miocene times. In addition to major marginal faults there are many tilted blocks which typify the pre-Miocene faulting. On the west some of these were eroded down to Basement before the deposition of Miocene sediments. In the east many such blocks exhibit only slight erosion and were probably not uplifted until late Oligocene times. The eastern boundary is marked by synthetic faults with downthrows of 1000 metres or more, but in one restricted area there is a downwarp broken by antithetic faults. The Miocene is characterized by anticlinal flexures generally associated with rejuvenation of Oligocene faults. There is no evidence of lateral movement but many of the faults follow ancient Pre-Cambrian trends. On the Sinai peninsula trend-lines show a twofold directional pattern, parallel to the Gulf of Akada and Gulf of Suez respectively. The angle between them suggests a series of conjugate pairs, originating as transcurrent faults in response to north-south compression. If this was the case, such strike-slip movements ceased before the deposition of the earliest Palaeozoic strata. These are at least as old as Carboniferous.

The area seems to have remained insulated from the great movements of lateral shiftwhich are claimed for the Akaba-Jordan rift and which are considered to be linked with the divergence of the Red Sea and the counter- clockwise rotation of Arabia. However, there is evidence to suggest that, since Eocene times, there has been a growing divergence of the margins of the Clysmic rift towards the south, producing a small counter-clockwise rotation of Sinai.
Atmospheric argon correction in the K-Ar dating of young volcanic rocks
Authors: FITCH FRANK JOHN , MILLER JOHN ALFRED
Published: December 2007

O
ne of the
fundamental assumptions of conventional potassium-argon dating is that the rock or mineral being dated was initially devoid of argon, i.e. that the argon sample prepared for analysis consists of radiogenic argon-40 accumulated during the life of the rock or mineral and a variable amount of modern atmospheric contamination alone. As the isotopic abundance ratio of argon in the atmosphere is known, it follows from this assumption that a measurement of the respective volumes of the isotopes argon-36 and argon-40 in the gas sample will enable the degree of atmospheric contamination to be established. Knowing this, the radiogenic component of the measured argon-40 volume can then be calculated. In young and/or low potassium-content samples atmospheric contamination becomes the major part of the gas sample and precise dating of such materials requires extremely accurate and precise measurements of the necessary atmospheric correction. Only mass spectrometers with very high stability and freedom from mass discrimination (such as the omegatron) are suitable for such work. Additionally, the assumption that initial argon is absent is probably never strictly true. The presence of even quite small quantities of initial argon invalidates the conventional atmospheric correction and can make the apparent ages obtained from young and especially from low potassium-content rocks drastically discrepant.

Initial argon may be present in young volcanic rocks and minerals in either or both of two ways:—

(i)
inherited:
e.g. from only partially outgassed (i.e. partially overprinted) xenoliths, xenocrysts or other non-juvenile components, or

(ii)
incorporated:
i.e. occluded or otherwise
A marine geological survey off the north-east coast of England (western North Sea)
Authors: DINGLE RICHARD VERNON
Published: December 2007

An area of approximately 5500 square miles of the North Sea was investigated using bottom sampling and seismic techniques. It lies on the north-western edge of the East English Basin, where extensive exposures of Mesozoic sediments are proved. Detailed mapping of these strata is possible over large areas; the western and southern parts of the region are shown to be extensions of the onshore Cleveland Basin and East Midland Shelf areas, with which they have had a comparable geological history. In the east, the Mesozoic strata are strongly folded as a result of halokinesis within evaporites of the English Zechstein Basin, and the feather edge of the main North Sea Tertiary Basin cuts across earlier structures, apparently unaffected. The main periods of earth movement affecting the area are late Jurassic/early Cretaceous, and ‘mid’-Tertiary in age. Important structural lines are recognised as demarcating the Cleveland Basin, East Midland Shelf, and halokinetic areas.
Thermal convection below the solidus in a mantled gneiss dome, Fungwi Reserve, Rhodesia
Authors: TALBOT CHRISTOPHER JOHN
Published: December 2007

Previously unrecorded structures inside a mantled gneiss dome are described and interpreted as having important geological implications.

The gneisses which make up this basement structure were domed on at least three scales near the thermal acme of the post-Umkondo 500 m.y. orogeny in the Zambezi orogenic belt. Groups of domes on one scale occur inside those of successively larger scales, forming a hierarchy of structures which are interpreted as being due mainly to gravitational, rather than lateral forces.

The rocks involved have an essentially uniform density at the present and it is argued that a concentration of the regional orogenic thermal gradient would have induced unstable density gradients capable of driving thermal convection below the range of temperatures at which the rocks would have melted. For the domes (or convection cells) to have been preserved in the manner in which they are found the convection can only have been due to marginal mechanical instability and must have been stabilized after the first half-cycle of motion. Heat is conducted faster parallel to a gneissose foliation than normal to it and, in restricted ranges of thermal gradients, the mechanism of heat transfer, conduction or convection-with-conduction, may depend solely on the attitude of the foliation in relation to the thermal gradient. The hierarchy of structures is interpreted as a chain reaction of alternations of conduction and convection caused by the rotation of this thermal anisotropy as the structures formed.

The genetic model suggested is tested and found to be geologically acceptable in termsthe thicknesses of the convecting layers, their effective viscosities, and the time necessary for each structural pattern to develop.

It is argued that had the regional orogenic thermal gradient persisted or been exceeded the incipient convection preserved in Fungwi would have become cyclic. This would have resulted in the homogenization of the granite- syenitic gneiss to what would subsequently look like a normal magmatic rock in a very short time geologically. Other basement domes in the region are interpreted as recording a predictable sequence of normal gneiss domesto completely ‘igneous’ plutons.

The production of homogeneous rocks from a gneissose basement by convective overturn may be anticipated as a reasonably common orogenic phenomenon inside local thickenings of mechanically uniform rock sequences. It is suggested that this simple mechanism is a link often assumed or alluded to by earlier writers who have described migma and magma domes in close proximity.
Palaeontological prospects—the use of fossils in stratigraphy
Authors: McKERROW WILLIAM STUART
Published: December 2007

T
he study
of fossils provides three main types of information:

1. the best method yet devised for recognising Phanerozoic time divisions over wide areas;

2. one of the best methods for distinguishing past sedimentary environments;

3. the only direct evidence of evolution through time, and thus a demonstration of the evolutionary relationships between those groups of animals and plants which have developed since the early Cambrian.

Palaeontology thus serves both Geology and Biology. This multiple service is even more evident today than in the past, especially in such fields as marine ecology. Not only are many modern ecological techniques being applied to fossil collecting, but the necessity to find out more about past environments has resulted in many palaeontologists wading and dredging to find out for themselves what is happening in modern seas.

This article is essentially a personal view of a palaeontologist who is attempting to use fossils to unravel past events and conditions in the light of present day processes. Of necessity, it cannot be a review of more than a small part of palaeontology. Most of the examples selected to illustrate this article are taken from fossil groups about which I have some experience; many of the points could equally well be made from other fossil groups. Drs. H. G. Reading and B. W. Sellwood have kindly made some comments on the typescript.

Fossils as time indicators

Some fossils can be used as a rough working basis for stratigraphy without considering them as much more than formed
Sedimentary environments and palaeogeography of the late Llandovery and earliest Wenlock of North Connemara, Ireland
Authors: PIPER DAVID JOHN WILLIAM
Published: December 2007

The upper Llandovery rocks of North Connemara record a gradual marine transgression at the northern margin of the Lower Palaeozoic geosyncline. The lowest rocks are red sandstones deposited from mainly southward flowing rivers
•
These are overlain by lagoon and coastal barrier sandstones and siltstones, and deeper water shelf siltstones. Red marine siltstones and mudstones, deposited in 100 to 200 m depth of water, are found near the top of the Llandovery sequence. Deeper water turbidite conglomerates and sandstones, with some thick mudstones, both overlie and laterally interfinger with the sequence of non-marine and shelf sediments. Basement faults controlled rates of subsidence during shelf sedimentation, and topographically defined the margins of turbidite accumulating basins. A palaeogeographic synthesis of the area is presented.
Some points of interest concerning the Silurian inliers of southwest central Ireland in their geosynclinal context:
a statement
Authors: HARPER JOHN CHILDS , BRENCHLEY PATRICK JOHN
Published: December 2007

In his discussion of geosynclinal development in the Silurian of the British Isles,
Ziegler (1970)
distinguishes land masses, shelf deposits, turbidite deposits and graptolitic shales. He further distinguishes between blocks such as the Midland Block and Eocaledonia (where passage from shelf to turbidite facies is sharp and associated with major fractures) and tectonic lands such as Cockburnland or the Irish Sea Land Mass (where the shelf record is only in the form of slumped shelly deposits).

Ziegler extrapolates his palaeogeographic maps across Ireland—a slimly documented area. He tentatively places the shelly succession of the Dingle Peninsula as part of the southern margin of Eocaledonia, and asserts that the turbidites and associated deposits of the Central Inliers seem to be related to the northern (Eocaledonian) margin of the trough. A contrary view has been suggested by Holland (1969 p. 208) who thinks that the Irish Sea Land Mass might have contributed sediments from the east.

Ziegler's palaeogeographic maps
(op. cir.
Figs. 3–6) show the trough as asymmetric, with turbidites mainly confined to the north-western side and graptolitic shales to the south-east. The evidence for this palaeogeographic interpretation in Ireland is slender and his conclusions are presumably based on his interpretation of the geology of the Central Inliers.

As will be seen in the following account there are some points concerning these inliers which are worthy of mention although their explanation is by no means clear.

The inliers are thought to fall into two groups and the argument for this is
The Karroo Volcanic Cycle
Authors: COX KEITH GORDON
Published: December 2007

The petrogenesis of all the Mesozoic igneous rocks of south-eastern Africa is considered in relation to a single unifying thermotectonic event postulated as initiating the disruption of Gondwanaland. The cycle began with the rise of a body of potassium-rich picrific magma from a depth of at least 500 km. This is the predominating source material for most of the rocks in the northern part of the province (e.g. Rhodesia). Overlying and peripheral to the main magma body a zone of normal (sodic) magma was generated and gave rise to some of the northern rocks and most of the southern rocks (e.g. Karroo dolerites, basalts of Lesotho and Swaziland). Initial eruptive products were locally well fractionated but gave way rapidly to highly primitive picritic lavas representing what is termed the culminatory stage of the cycle. A subsequent stage in which the basalts emitted remained relatively uniform and moderately fractionated over a long period of time is referred to as the 'steady state' phase. A waning stage may be represented by more salic rocks such as the phonolites of Lupata (Mozambique) and the associated plutons of the Chilwa province (Malawi). The Cretaceous kimberlites of Southern Africa may represent the terminal igneous activity of the cycle. Superimposed on the cycle of mantle-derived rocks is a minor cycle of anatexis in the crust which gave rise to most of the acid rocks of the province, particularly the rhyolites of the Lebombo monocline. It is suggested that other provinces such as the Deccan Traps and the Tertiary of Greenland may show patterns of igneous activity which are similar to the Karroo cycle in important respects.
Carbonatite-derived sediments in southeast Uganda
Authors: BLOOMFIELD KEITH
Published: December 2007

F
ive carbonatite complexes
of probable Lower Miocene age occur along a
nne–ssw
line some 65 km in length in the southeast of Uganda, close to the Kenya border (
King & Sutherland 1966
). They are associated with the major central-type alkaline volcanoes of Mount Elgon and Kadam (Fig.
1
) which may also be assigned to the Lower Miocene on the basis of recent K-Ar age determinations (
Bishop, Miller & Fitch 1969
).

Sub-volcanic sediments, termed the Bugisu Series, crop out sporadically on the periphery of Mount Elgon and partly underlie Nkokonjeru, a neighbouring volcanic outlier. This Series was first described by Davies (1952 p. 7), who inferred four separate lacustrine basins of sedimentary deposition, three near the edges of the main Mount Elgon volcanic pile and the fourth underlying Nkokonjeru. Later, the Geological Survey of Uganda carried out a pitting and drilling programme on the northern slopes of Nkokonjeru and located various sub-horizontal sediments classified as ‘calcareous tuffs’, ‘ashy limestones’, and conglomerates in the lower part of the sequence.

The writer made a petrographic examination of available drill-core and found that most of the rocks were calcarenites and calcirudites containing abundant magnetite and apatite with small amounts of detrital pyrochlore––all apparently derived from carbonatites. Accordingly a detailed survey of the Nkokonjeru area was carried out, accompanied by intensive geochemical stream sediment sampling. This note summarizes the results.
Geophysical evidence concerning the structure of the Lewisian of Sutherland, N.W. Scotland
Authors: BOTT MARTIN HAROLD PHILLIPS , HOLLAND JAMES GRENVILLE , STORRY PETER GRAHAM , WATTS ANTHONY BRIAN
Published: December 2007

Interpretation of two new gravity profiles across the Ben Stack line and of the I.G.S. aeromagnetic map indicates that the Lewisian biotite-gneisses occurring to the north of this line are underlain at a depth of about 3 km or less by rocks possessing similar density and magnetic properties to the pyroxene-granulites which crop out south of the line. The Ben Stack line forms the fundamental division between these two metamorphic assemblages of the Lewisian and its plane dips steeply towards the south. The gravity profiles also indicate that both the biotite-gneisses and pyroxene-granulites in the vicinity of the Ben Stack line are anomalously low in density. This is attributed to the penetration of both formations by granitic and pegmatitic intrusions of low density. The evidence suggests that the granitic material concentrated in the vicinity of the Ben Stack line occupies too great a volume to be derived solely from the host biotite-gneisses in the immediate vicinity and may therefore possibly be of more extensive origin.
Refraction seismic surveys in the north Irish Sea
Authors: BACON MICHAEL , McQUILLIN ROBERT
Published: December 2007

Results of refraction work in the northern Irish Sea confirm the presence of sedimentary basins of presumed Permo-Triassic age in the Solway Firth and the eastern Irish Sea. A gravity low west of the Isle of Man is, however, more probably largely due to a granite.
Letter to the Editor
Authors: Powell Derek , Saxena Mahendra
Published: December 2007

Sir,

The recent short communication concerning tillite horizons in the Chamba Himalayas of N. India (Powell and Saxena,
J. geol. Soc. Lond.
1971, p. 595) has prompted letters from Dr. J. B. Auden and Dr. V. J. Gupta. Dr. Auden has kindly pointed out our error in quoting Auden 1935 instead of Auden 1934 and 1955. He also draws attention to papers pertinent to the general discnssion of Himalayan Tillites, viz. Auden 1943, 1946, 1947, 1958 and Pilgrim and West 1928.

Dr. Gupta suggests an Upper Carboniferous to Permian age for tillltes in the Chamba area. The authors' tentative conclusion of a lower Carboniferous or older age for the Kalhel and Durgatti deposits was based on evidence presented by Gupta and Bedi (1970). Dr. Gupta now suggests the younger age for the tillites near Kalhel (Fuchs and Gupta 1971) on the basis of the presence of
Spirifer nagmargensis, S. nitrensis,
etc. in associated rocks. In support of this conclusion he cites Datta and Bhattacharya 1971 who report
Spiriferella rajah, Productus sp.
and
Modiola lidarensis
from the ‘Agglomeratic Slates’ in the north-eastern part of the Chamba area.

It is, however, not clear in Gupta (1970) or Fuchs and Gupta (1971) what is the detailed rock succession at Kalhel or how it can be correlated with the Agglomeratic Slates of Kashmir.

The new evidence from Dr. Gupta is welcome since only with more faunal evidence accurately located, will difficulties of correlation and dating be resolved.
Magmatic sedimentation and carbonatitic differentiation in kimberlite sills at Benfontein, South Africa
Authors: DAWSON JOHN BARRY , HAWTHORNE JOHN BARRY
Published: December 2007

At Benfontein, near Kimberley, South Africa, three sills of kimberlite intrude Dwyka shales and overlying Karroo dolerite. Each sill results from numerous injections of kimberlite that have consolidated to give the sill a layered appearance. Many layers show magmatic sedimentation features and cumulus textures, and, although some show
in situ
differentiation, other layers result from pre-injection differentiation. The transporting, intercumulus liquid was carbonate-rich and some layers have differentiated to form a carbonate rock composed of the intercumulns calcite; this, on trace element and isotopic data, shows strong affinities with carbonatite. In one of the sills one calcite layer has migrated diapirically into overlying layers in the sill. These sedimentation features, combined with thermal metamorphism of country-rock shales and the presence of quench calcite and apatite, are interpreted as evidence that the kimberlite was injected as a highly mobile fluid, comprising megacrysts of olivine, garnet, pyroxene, mica and picroilmenite in a hot carbonatitic liquid from which olivine, magnetic spinel, perovskite, apatite, calcite, dolomite, ankerite and quartz crystallised. The evidence that the transportation medium was a warm carbonatitic liquid is directly opposed to earlier hypotheses proposing that kimberlite is intruded as a cold or plastic paste, and also supports proposals of a genetic link between kimberlite and carbonatite.
Scourian-Laxfordian relationships in the Barra Isles
Authors: FRANCIS PETER W.
Published: December 2007

The Lewisian rocks of Barra are a Laxfordian supra-structure of amphibolite facies gneisses and a Scourian infra-structure characterised by orthopyroxene bearing gneisses. Both units contain representatives of the Scourie Dyke suite; in the supra-structure they are highly deformed and folded; in the infra-structure they are relatively undeformed, unfolded, and retain original discordant relationships. The infra-structure also has several suites of intrusive igneous rocks earlier than the Scourie dyke suite, the most widespread being dykes of dioritic composition.

The same sequence of Laxfordian deformation may be recognised in both units. Folding occurred in the supra-structure under amphibolite facies conditions, which continued after deformation ceased. In the infra-structure, evidence for a pre-Scourie dyke pyroxene granulite facies metamorphism is preserved. The Scourie dykes of the infra-structure have pyroxene granulite facies mineral assemblages resulting from intrusion into hot or dry country rock gneisses.

Probably a very old cover to basement relationship is preserved in the area, which was first deformed in the Scourian orogeny, and then subsequent Laxfordian deformation of the interface between the two major units produced overall structure of the area.
Volcanic islands of the Red Sea
Authors: GASS IAN G. , MALLICK DONALD I. J. , COX KEITH G.
Published: December 2007

The Recent volcanic islands of the Red Sea are (1) Jebel at Tair, a single small volcano of tholeiitic basalt lava; (2) the Zubair Islands with pyroclastic cones and flows intermediate between tholeiite and alkali basalt and with picrite basalt and trachybasalt blocks in the agglomerates; (3) the Hanish-Zukur Islands with alkali basalts accompanied by trachybasalts, trachyandesites and trachytes together with pyroclastic rocks. The chemistry of 46 lava specimens indicates that a gradational series exists between the sea-floor basalts (K-poor tholeiites) and the alkali basalts of Hanish-Zukur, with the rocks of Jebel at Tair and Zubair representing intermediate stages. Two alternative petrogenetic models are discussed to account for this gradational behaviour. One derives the parental magma from successively greater depths, the other considers derivation by successively greater fractionation on route to the surface. The relationship of the volcanoes to the opening of the Red Sea is discussed. Possibly, eruptive activity was initiated at the southern end and is migrating northwards in response to the anticlockwise rotation of Arabia relative to Africa. The Red Sea axial trough may die out southwards owing to vocanic fill from the Hanish-Zukur volcanoes.
The geology of the continental shelf between Luderitz and Cape Town (Southwest Africa), with special reference to Tertiary strata
Authors: DINGLE RICHARD V.
Published: December 2007

The geology and morphology of the continental shelf between Luderitz and Cape Town are described. The shelf is shown to be a thick sediment wedge constructed mainly during Cretaceous times, with a thin capping of Lower Tertiary, Upper Tertiary and Holocene sediments. Shallow-water sediments dominate the Upper Tertiary succession, and four main facies are identified which are controlled to a great extent by the Lower Tertiary ridge; a topographical high possibly representing secondary features related to basement structures at depth. ?Coniacian, ?Eocene, ?Miocene and ?Pliocene transgressions are recognized.

Earliest Cretaceous sediments are probably Aptian or earlier. A progressive decrease in the sedimentation rate since Cretaceous times is postulated and present-day regional disparities in shelf depth are explained in the light of subsidence and sedimentation rates. The double shelf break has been in existence since at least Lower Tertiary times and has been periodically modified by erosion and sedimentation. Bottom currents have kept the outer shelf area sediment-free since ?Pliocene times. The distribution of organic-rich and authigenic mineral-rich sediments is mentioned.