Sediment-matrix igneous breccias at the top contacts of felsic units in the IPB : implications for VHMS exploration

The Volcanic Sedimentary Complex of the Iberian Pyrite Belt is dominated by mudstone units and comprises felsic lavas/domes and pyroclastic units that define lava-cryptodome-pumice cone volcanoes. Sediment-matrix igneous breccias may outline the contacts of volcanic units, occur within them, or lie laterally to the volcanic centres. These breccias can form by several processes, each with its genetic implications, having nevertheless very similar final aspect. We have distinguished and characterized several sediment-matrix breccia types. The most abundant types are sediment-infill volcanic breccia and peperite; however other types of sediment-matrix breccia were also identified. The correct identification of these breccias is crucial to reconstruct the volcanic centres and to define the stratigraphy, which in mineralized volcanic provinces is a major issue both for metallogenic and mineral exploration models

Volcanic facies architecture, hydrothermal alteration and subsea-floor replacement at the Neves Corvo deposit, Iberian Pyrite Belt

Contribution to research project ARCHYMEDESII-POCTI/CTA/45873/2002.Three felsic volcanic sequences constitute the host succession to the Neves Corvo VHMS deposit. The lower volcanic sequence (late Famennian) consists of a rhyolitic fiamme-rich facies association that comprises polymictic and overall graded quartzphyric fiamme breccia units (up to 60 m thick). These units have pyroclastic origin and constitute the substrate to the rhyolite facies association (intermediate volcanic sequence). The rhyolite facies association (late Strunian) comprises intervals of coherent quartz-feldspar-phyric rhyolite (up to 10 m thick) that are enclosed by much thicker intervals (up to 250 m) of jigsaw-fit and clast-rotated monomictic rhyolite breccia. Laterally these breccias grade to beds of monomictic rhyolite breccia that alternate with crystal-rich sandstone. The units defined by the rhyolite facies association are rhyolitic lavas. The massive sulfide orebodies (late Strunian) directly overly the lavas or are interleaved with relatively thin (up to 50 m) intervals of mudstone. The upper volcanic sequence (early Visean) consists of a thin interval of monomictic dacite breccia. The host succession to the Neves Corvo orebodies thus comprises proximal to source vent deposits from submarine explosive and effusive eruptions. However, the ore-forming process relates both in time and space with the rhyolitic lavas, which are coeval with the mineralization. Neves Corvo is well known for its high-grade Cu ores and unique cassiterite mineralization. Ore-related hydrothermal activity overprints an early metasomatic stage and relates with a multi-sourced hydrothermal system, responsible for early stringer and massive cassiterite deposition and subsequent massive sulfide oregeneration. In the Corvo orebody, the early deposition of massive cassiterite ores was fed by an independent stockwork in a tectonically-bounded alignment. Textural and petrographic analyses, geochemistry and oxygen-isotope data indicate brusque flushing of the tin-bearing fluid into seawater after minimal fluid-rock interaction during up flow. Massive sulfide-related hydrothermal alteration is essentially stratabound and controlled by permeability contrasts. Alteration zonation is classical, consisting of an inner chlorite/donbassite-quartz-sulfides-(sericite) core that grades into sericitequartz- sulfides-(chlorite) and paragonite-quartz-sulfides-(chlorite) peripheral envelopes. The aluminous hydrothermal alteration mineralogy coupled with elemental and stable isotope geochemistry indicates very low pH, unusually high maximum interaction temperature and predominant low-sulfidation alteration/mineralization conditions. Textural and mass-balance analyses show extensive silicate-sulfide replacement in the coherent volcanic rocks of the footwall sequence, and disseminated replacement mineralization in the volcaniclatic/sedimentary units

Erosion Surface and Granitic Morphology in the Sierra de Lihuel Calel, Province of La Pampa, Argentina

Fil: Aguilera, Emilia Yolanda. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Sato, Ana María. Centro de Investigaciones Geológicas (CIG). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Llambías, Eduardo Jorge. Centro de Investigaciones Geológicas (CIG). Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Tickyj, Hugo. Departamento de Ciencias Naturales. Facultad de Ciencias Exactas y Naturales. Universidad Nacional de La Pampa; Argentin

Time-lapse characterization of hydrothermal seawater and microbial interactions with basaltic tephra at Surtsey Volcano

A new International Continental Drilling Program (ICDP) project will drill through the 50-yearoldedifice of Surtsey Volcano, the youngest of the Vestmannaeyjar Islands along the south coast of Iceland, to perform interdisciplinary time-lapse investigations of hydrothermal and microbial interactions with basaltic tephra. The volcano, created in 1963–1967 by submarine and subaerial basaltic eruptions, was first drilled in 1979. In October 2014, a workshop funded by the ICDP convened 24 scientists from 10 countries for 3 and a half days on Heimaey Island to develop scientific objectives, site the drill holes, and organize logistical support. Representatives of the Surtsey Research Society and Environment Agency of Iceland also participated. Scientific themes focus on further determinations of the structure and eruptive processes of the type locality of Surtseyan volcanism, descriptions of changes in fluid geochemistry and microbial colonization of the subterrestrial deposits since drilling 35 years ago, and monitoring the evolution of hydrothermal and biological processes within the tephra deposits far into the future through the installation of a Surtsey subsurface observatory. The tephra deposits provide a geologic analog for developing specialty concretes with pyroclastic rock and evaluating their long-term performance under diverse hydrothermal conditions

How is Perceived Community Cohesion and Membership in Community Groups Associated with Children’s Dietary Adequacy in Disadvantaged Communities? A Case of the Indian Sundarbans

Background: Membership in community groups and a sense of community cohesion may facilitate collective action in mobilizing resources towards better health outcomes. This paper explores the relationship of these factors, along with individual level socio-economic variables, to dietary adequacy among children below 6 years of age, a proximate determinant of child malnutrition. Methods: We conducted a cross-sectional survey in Patharpratima block of the Sundarbans in West Bengal, India, using a two-stage, 30 cluster random sampling design. In 1200 sampled households, we used a structured questionnaire to interview mothers of children below 6 years of age on their child’s nutritional intake. We also interviewed household heads to assess perceived community cohesion using a nine item scale, membership in any community self-help organization, and other socio-economic determinants. We used a logistic regression model to assess their association with a minimum acceptable diet among children between 6 months to 6 years. Results: Only 9.33 % children between 6 and 71 months of age received a minimum acceptable diet. With each increase in the perceived community cohesion score (scale 0-9), a child is 1.31 times more likely to have minimum acceptable diet (95 % CI 1.14, 1.50). The odds of minimum acceptable diet were also higher among children whose mothers had primary education (2.09, 95 % CI 1.03, 2.94) as compared to illiterate mothers and in households with surplus food resources (2.72, 95 % CI 1.32, 5.58) as compared to those without surplus or deficit. In contrast, registering at an Anganwadi (government early child development) centre (odds ratio 1.34 95 % CI 0.69, 2.60) and community membership (odds ratio 0.93, 95 % CI 0.59, 1.46) were not associated with minimum acceptable diet. Conclusion: The results are consistent with what is known about the importance of maternal education and access to food resources in ensuring that children have a minimum acceptable diet. Perceived community cohesion seems to play a positive role in children’s diets. Further research needs to clarify which community characteristics and services are the most relevant, how they can better support children’s diets, and how interventions can strengthen these community characteristics and services

Three-Dimensional Stochastic Off-Lattice Model of Binding Chemistry in Crowded Environments

Molecular crowding is one of the characteristic features of the intracellular environment, defined by a dense mixture of varying kinds of proteins and other molecules. Interaction with these molecules significantly alters the rates and equilibria of chemical reactions in the crowded environment. Numerous fundamental activities of a living cell are strongly influenced by the crowding effect, such as protein folding, protein assembly and disassembly, enzyme activity, and signal transduction. Quantitatively predicting how crowding will affect any particular process is, however, a very challenging problem because many physical and chemical parameters act synergistically in ways that defy easy analysis. To build a more realistic model for this problem, we extend a prior stochastic off-lattice model from two-dimensional (2D) to three-dimensional (3D) space and examine how the 3D results compare to those found in 2D. We show that both models exhibit qualitatively similar crowding effects and similar parameter dependence, particularly with respect to a set of parameters previously shown to act linearly on total reaction equilibrium. There are quantitative differences between 2D and 3D models, although with a generally gradual nonlinear interpolation as a system is extended from 2D to 3D. However, the additional freedom of movement allowed to particles as thickness of the simulation box increases can produce significant quantitative change as a system moves from 2D to 3D. Simulation results over broader parameter ranges further show that the impact of molecular crowding is highly dependent on the specific reaction system examined

Rapid semi-automated quantitative multiplex tandem PCR (MT-PCR) assays for the differential diagnosis of influenza-like illness

<p>Abstract</p> <p>Background</p> <p>Influenza A, including avian influenza, is a major public health threat in developed and developing countries. Rapid and accurate detection is a key component of strategies to contain spread of infection, and the efficient diagnosis of influenza-like-illness is essential to protect health infrastructure in the event of a major influenza outbreak.</p> <p>Methods</p> <p>We developed a multiplexed PCR (MT-PCR) assay for the simultaneous diagnosis of respiratory viruses causing influenza-like illness, including the specific recognition of influenza A haemagglutinin subtypes H1, H3, and H5. We tested several hundred clinical specimens in two diagnostic reference laboratories and compared the results with standard techniques.</p> <p>Results</p> <p>The sensitivity and specificity of these assays was higher than individual assays based on direct antigen detection and standard PCR against a range of control templates and in several hundred clinical specimens. The MT-PCR assays provided differential diagnoses as well as potentially useful quantitation of virus in clinical samples.</p> <p>Conclusions</p> <p>MT-PCR is a potentially powerful tool for the differential diagnosis of influenza-like illness in the clinical diagnostic laboratory.</p